METHOD FOR PREPARING HIGH-MELTING-POINT METAL POWDER THROUGH MULTI-STAGE DEEP REDUCTION

Abstract

The invention relates to a method for preparing high-melting-point metal powder through multi-stage deep reduction, and belongs to the technical field of preparation of powder. The method includes the following steps of mixing dried high-melting-point metal oxide powder with magnesium powder and performing a self-propagating reaction, placing an intermediate product into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution so as to obtain a low-valence oxide Me.sub.xO precursor of the low-valence high-melting-point metal; uniformly mixing the precursor with calcium powder, pressing the mixture, placing the pressed mixture into a vacuum reduction furnace, heating the vacuum reduction furnace to 700-1200 C., performing deep reduction for 1-6 h, leaching a deep reduction product with hydrochloric acid as a leaching solution and performing treatment, so as to obtain the high-melting-point metal powder.

Claims

1. A method for preparing a high-melting-point metal powder through a multi-stage deep reduction, comprising the following steps: step 1, performing a self-propagating reaction: drying a high-melting-point metal oxide powder to obtain a dried high-melting-point metal oxide powder, mixing the dried high-melting-point metal oxide powder with magnesium (Mg) powder to obtain mixed materials, adding the mixed materials into a self-propagating reaction furnace to perform the self-propagating reaction, and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of a high-melting-point metal (Me) is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, x is 0.2-1, the high-melting-point metal specifically comprises one or more of W, Mo, Ta, Nb, V, Zr, Hf and Re, the high-melting-point metal oxide is one or a mixture of several kinds of WO.sub.3, MoO.sub.3, Ta.sub.2O.sub.5, Nb.sub.2O.sub.5, V.sub.2O.sub.5, ZrO.sub.2, HfO.sub.2 and Re.sub.2O.sub.7, and when the high-melting-point metal oxide is WO.sub.3, a mixing proportion in molar ratio of WO.sub.3 to Mg is 1 to (0.8-1.2), when the high-melting-point metal oxide is MoO.sub.3, a mixing proportion in molar ratio of MoO.sub.3 to Mg is 1 to (0.8-1.2), when the high-melting-point metal oxide is Ta.sub.2O.sub.5, a mixing proportion in molar ratio of Ta.sub.2O.sub.5 to Mg is 1 to (2.7-3.3), when the high-melting-point metal oxide is Nb.sub.2O.sub.5, a mixing proportion in molar ratio of Nb.sub.2O.sub.5 to Mg is 1 to (2.7-3.3), when the high-melting-point metal oxide is V.sub.2O.sub.5, a mixing proportion in molar ratio of V.sub.2O.sub.5 to Mg is 1 to (2.7-3.3), when the high-melting-point metal oxide is ZrO.sub.2, a mixing proportion in molar ratio of ZrO.sub.2 to Mg is 1 to (0.8-1.2), when the high-melting-point metal oxide is HfO.sub.2, a mixing proportion in molar ratio of HfO.sub.2 to Mg is 1 to (0.8-1.2), and when the high-melting-point metal oxide is Re.sub.2O.sub.7, a mixing proportion in molar ratio of Re.sub.2O.sub.7 to Mg is 1 to (2.7-3.3); step 2, performing a primary leaching: placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product, and performing vacuum drying on the washed leaching product to obtain a low-valence oxide Me.sub.xO precursor of the low-valence high-melting-point metal, wherein a molar concentration of hydrochloric acid is 1-6 mol/L; step 3, performing the multi-stage deep reduction: uniformly mixing the low-valence oxide Me.sub.xO precursor of the low-valence high-melting-point metal with calcium (Ca) powder, performing pressing at 2-20 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating to 700-1,200 C., performing a secondary deep reduction for 1-6 h, obtaining a block billet after the secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein a molar ratio is described as follows: Me.sub.xO:Ca=1:(1.5-3); and step 4, performing a secondary leaching: placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution to obtain a filtrate and filter residues, removing the filtrate, washing the filter residues and performing vacuum drying to obtain a low-oxygen high-melting-point metal powder, wherein a molar concentration of hydrochloric acid is 1-6 mol/L, the low-oxygen high-melting-point metal powder comprises the following ingredients by percentage by mass of equal to or smaller than 0.8% of O, greater than or equal to 99% of the high-melting-point metal and a balance of inevitable impurities, and a particle size of the low-oxygen high-melting-point metal powder is 5-60 m.

2. The method according to claim 1, wherein in the step 1, the drying is performed in a specific operation step of placing the high-melting-point metal oxide powder into a drying oven, and performing the drying at a temperature of 100-150 C. for 24 h or above.

3. The method according to claim 1, wherein in the step 1, the mixed materials are treated in one of the following two ways before being added into the self-propagating reaction furnace: a first treatment way comprises the following steps: pressing the mixed materials under 10-60 MPa to obtain the block blank, adding the block blank into the self-propagating reaction furnace and performing the self-propagating reaction; and a second treatment way comprises the following steps: directly adding the mixed materials into the self-propagating reaction furnace without treatment and performing the self-propagating reaction.

4. The method according to claim 1, wherein in the step 1, initiation modes of the self-propagating reaction are respectively a local ignition method and an overall heating method, wherein the local ignition method refers to heating a local part of the mixed materials by an electric heating wire in the self-propagating reaction furnace to initiate the self-propagating reaction; the overall heating method refers to raising a temperature of the whole mixed materials in the self-propagating reaction furnace until the self-propagating reaction occurs, and the temperature is controlled at 500-750 C.

5. The method according to claim 1, wherein in the step 2, when the intermediate product is leached, diluted hydrochloric acid and the intermediate product are in cooperation in a manner that an adding amount of the diluted hydrochloric acid is 10-40% in excess of the hydrochloric acid required by a reaction theory; and in the step 2, a leaching temperature for leaching the intermediate product is 20-30 C., and a leaching time is 60-180 min.

6. The method according to claim 1, wherein in the step 2, the low-valence oxide Me.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 5-20% of O, smaller than or equal to 0.5% of the inevitable impurities and a balance of the high-melting-point metal, wherein the particle size is 0.8-15 m.

7. The method according to claim 1, wherein in the step 2, the washing process and the vacuum drying process comprise the following specific steps: washing the leaching product without the leaching solution with water until a washing solution is neutral, and then drying the washed leaching product in a vacuum drying oven at a temperature of 20-30 C. for at least 24 h; and the washing is performed with water and specifically refers to dynamic washing, in which the washing solution in a washing tank is kept at a constant water level in the washing process, fresh water with the same amount of a drained washing liquid is supplemented, and the leaching product is washed until the washing liquid is neutral.

8. The method according to claim 1, wherein in the step 3, a reaction parameter for the secondary deep reduction lies in that heating is performed under the condition that the vacuum degree is less than or equal to 10 Pa.

9. The method according to claim 1, wherein in the step 4, when the deep reduction product is leached, diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that an adding amount of the diluted hydrochloric acid is 5-30% in excess of the hydrochloric acid required by a reaction theory; and in the step 4, a leaching temperature for leaching the deep reduction product is 20-30 C., and a leaching time is 15-90 min.

10. The method according to claim 1, wherein in the step 4, the washing process and the vacuum drying process comprise the following specific steps: washing the leaching product without the leaching solution with water until a washing solution is neutral, and then drying the washed leaching product in a vacuum drying oven at s temperature of 20-30 C. for at least 24 h; and the washing is performed with water and specifically refers to dynamic washing, in which the washing solution in a washing tank is kept at a constant water level in the washing process, fresh water with the same amount of a drained washing liquid is supplemented, and the leaching product is washed until the washing liquid is neutral.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] FIGURE is a process flow chart of a method for preparing high-melting-point metal powder through multi-stage deep reduction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0048] The invention is further described in details through combination with an embodiment.

[0049] High-melting-point metal oxide powder, magnesium powder, calcium powder and hydrochloric acid used in the following embodiment are all industrial grade products. Particle sizes of the high-melting-point metal oxide powder, the magnesium powder and the calcium powder are smaller than equal to 0.5 mm.

[0050] A self-propagating reaction furnace used in the following embodiment is a self-propagating reaction furnace disclosed in the patent ZL200510047308.2. The reaction furnace consists of a reaction container, a heater, a sight glass, a transformer, a function recorder, a thermocouple and a vent valve.

[0051] The time of a self-propagating reaction in the following embodiment is 5-90 s.

[0052] The drying time in the following embodiment is at least 24 h.

[0053] In the following embodiment, a process flow chart of the method for preparing high-melting-point metal powder through multi-stage deep reduction is shown in FIGURE.

Embodiment 1

[0054] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0055] Step 1, Performing Self-Propagating Reaction:

[0056] Placing tungsten oxide powder in a drying oven, drying the tungsten oxide powder at the temperature of 100-150 C. for 24 h to obtain dried tungsten oxide powder, mixing the dried tungsten oxide powder with the magnesium powder according to a molar ratio of WO.sub.3 to Mg being 1 to 1 to obtain mixed materials, pressing the mixed materials at 20 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 500 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0057] Step 2, Performing Primary Leaching:

[0058] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 25 C. and the leaching time is 120 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 20 C. for 24 h to obtain an oxide W.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 2 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 10-40% in excess of hydrochloric acid required by a reaction theory, and

[0059] The oxide W.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 12% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0060] Step 3, Performing Multi-Stage Deep Reduction:

[0061] Uniformly mixing the oxide W.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 5 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 1000 C., performing secondary deep reduction for 2 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: W.sub.xO:Ca=1:2; and

[0062] Step 4, Performing Secondary Leaching:

[0063] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 25 C. for 30 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 30 C. for 24 h under a vacuum condition to obtain low-oxygen tungsten powder, wherein the molar concentration of hydrochloric acid is 1 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 5-30% in excess of hydrochloric acid required by a reaction theory; and

[0064] The low-oxygen tungsten powder comprises the following ingredients in percentage by mass: 99.3% of W, 0.34% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 38 m.

Embodiment 2

[0065] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0066] Step 1, Performing Self-Propagating Reaction:

[0067] Placing tungsten oxide powder in a drying oven, drying the tungsten oxide powder at the temperature of 100-150 C. for 24 h to obtain dried tungsten oxide powder, mixing the dried tungsten oxide powder with the magnesium powder according to a molar ratio of WO.sub.3 to Mg being 1 to 1.2 to obtain mixed materials, pressing the mixed materials at 10 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 750 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0068] Step 2, Performing Primary Leaching:

[0069] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 25 C. and the leaching time is 120 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 20 C. for 24 h to obtain an oxide W.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 1 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 10% in excess of hydrochloric acid required by a reaction theory, and

[0070] The oxide W.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 20% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0071] Step 3, Performing Multi-Stage Deep Reduction:

[0072] Uniformly mixing the oxide W.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 10 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 900 C., performing secondary deep reduction for 3 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: W.sub.xO:Ca=1:2.2; and

[0073] Step 4, Performing Secondary Leaching:

[0074] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 25 C. for 15 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 30 C. for 24 h under a vacuum condition to obtain low-oxygen tungsten powder, wherein the molar concentration of hydrochloric acid is 2 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 10% in excess of hydrochloric acid required by a reaction theory; and

[0075] The low-oxygen tungsten powder comprises the following ingredients in percentage by mass: 99.5% of W, 0.13% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 28 m.

Embodiment 3

[0076] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0077] Step 1, Performing Self-Propagating Reaction:

[0078] Placing tungsten oxide powder in a drying oven, drying the tungsten oxide powder at the temperature of 100-150 C. for 24 h to obtain dried tungsten oxide powder, mixing the dried tungsten oxide powder with the magnesium powder according to a molar ratio of WO.sub.3 to Mg being 1 to 0.8 to obtain mixed materials, pressing the mixed materials at 60 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 650 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0079] Step 2, Performing Primary Leaching:

[0080] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 25 C. and the leaching time is 60 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 30 C. for 24 h to obtain an oxide W.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 6 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 10% in excess of hydrochloric acid required by a reaction theory, and

[0081] The oxide W.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 5% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0082] Step 3, Performing Multi-Stage Deep Reduction:

[0083] Uniformly mixing the oxide W.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 15 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 1100 C., performing secondary deep reduction for 2 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: W.sub.xO:Ca=1:3; and

[0084] Step 4, Performing Secondary Leaching:

[0085] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 20 C. for 30 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 25 C. for 24 h under a vacuum condition to obtain low-oxygen tungsten powder, wherein the molar concentration of hydrochloric acid is 1 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 30% in excess of hydrochloric acid required by a reaction theory; and

[0086] The low-oxygen tungsten powder comprises the following ingredients in percentage by mass: 99.6% of W, 0.09% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 41 m.

Embodiment 4

[0087] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0088] Step 1, Performing Self-Propagating Reaction:

[0089] Placing molybdenum oxide powder in a drying oven, drying the molybdenum oxide powder at the temperature of 100-150 C. for 24 h to obtain dried molybdenum oxide powder, mixing the dried molybdenum oxide powder with the magnesium powder according to a molar ratio of MoO.sub.3 to Mg being 1 to 1.1 to obtain mixed materials, pressing the mixed materials at 20 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 550 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0090] Step 2, Performing Primary Leaching:

[0091] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 25 C. and the leaching time is 90 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 30 C. for 24 h to obtain an oxide Mo.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 4 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 10% in excess of hydrochloric acid required by a reaction theory, and

[0092] The oxide Mo.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 10% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 jam;

[0093] Step 3, Performing Multi-Stage Deep Reduction:

[0094] Uniformly mixing the oxide Mo.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 5 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 900 C., performing secondary deep reduction for 3 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: Mo.sub.xO:Ca=1:2.4; and

[0095] Step 4, Performing Secondary Leaching:

[0096] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 30 C. for 20 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 25 C. for 24 h under a vacuum condition to obtain low-oxygen molybdenum powder, wherein the molar concentration of hydrochloric acid is 2 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 5-30% in excess of hydrochloric acid required by a reaction theory; and

[0097] the low-oxygen molybdenum powder comprises the following ingredients in percentage by mass: 99.0% of Mo, 0.31% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 28 m.

Embodiment 5

[0098] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0099] Step 1, Performing Self-Propagating Reaction:

[0100] Placing molybdenum oxide powder in a drying oven, drying the molybdenum oxide powder at the temperature of 100-150 C. for 24 h to obtain dried molybdenum oxide powder, mixing the dried molybdenum oxide powder with the magnesium powder according to a molar ratio of MoO.sub.3 to Mg being 1 to 0.8 to obtain mixed materials, pressing the mixed materials at 40 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 700 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0101] Step 2, Performing Primary Leaching:

[0102] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 25 C. and the leaching time is 100 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 20 C. for 24 h to obtain an oxide Mo.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 2 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 10% in excess of hydrochloric acid required by a reaction theory, and

[0103] The oxide Mo.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 10% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0104] Step 3, Performing Multi-Stage Deep Reduction:

[0105] Uniformly mixing the oxide Mo.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 15 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 1000 C., performing secondary deep reduction for 2 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: Mo.sub.xO:Ca=1:2; and

[0106] Step 4, Performing Secondary Leaching:

[0107] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 20-30 C. for 30 min to obtain filtrate and filter residues, removing the filtrate, washing the leaching product in a dynamic washing mode and drying the washed filter residues at the temperature of 25 C. for 24 h under a vacuum condition to obtain low-oxygen molybdenum powder, wherein the molar concentration of hydrochloric acid is 1 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 5-30% in excess of hydrochloric acid required by a reaction theory; and

[0108] the low-oxygen molybdenum powder comprises the following ingredients in percentage by mass: 99.2% of Mo, 0.34% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 33 m.

Embodiment 6

[0109] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0110] Step 1, Performing Self-Propagating Reaction:

[0111] Placing molybdenum oxide powder in a drying oven, drying the molybdenum oxide powder at the temperature of 100-150 C. for 24 h to obtain dried molybdenum oxide powder, mixing the dried molybdenum oxide powder with the magnesium powder according to a molar ratio of MoO.sub.3 to Mg being 1 to 1 to obtain mixed materials, pressing the mixed materials at 30 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 520 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0112] Step 2, Performing Primary Leaching:

[0113] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 30 C. and the leaching time is 120 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 20 C. for 24 h to obtain an oxide Mo.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 1 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 35% in excess of hydrochloric acid required by a reaction theory, and

[0114] The oxide Mo.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 12% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0115] Step 3, Performing Multi-Stage Deep Reduction:

[0116] Uniformly mixing the oxide Mo.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 5 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 1100 C., performing secondary deep reduction for 2 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: Mo.sub.xO:Ca=1:3; and

[0117] Step 4, Performing Secondary Leaching:

[0118] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 20-30 C. for 15 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 25DEG C. for 24 h under a vacuum condition to obtain low-oxygen molybdenum powder, wherein the molar concentration of hydrochloric acid is 3 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 5-30% in excess of hydrochloric acid required by a reaction theory; and

[0119] The low-oxygen molybdenum powder comprises the following ingredients in percentage by mass: 99.4% of Mo, 0.37% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 44 m.

Embodiment 7

[0120] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0121] Step 1, Performing Self-Propagating Reaction:

[0122] Placing tantalum oxide powder in a drying oven, drying the tantalum oxide powder at the temperature of 100-150 C. for 24 h to obtain dried tantalum oxide powder, mixing the dried tantalum oxide powder with the magnesium powder according to a molar ratio of Ta.sub.2O.sub.5 to Mg being 1 to 3 to obtain mixed materials, pressing the mixed materials at 20 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 720 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0123] Step 2, Performing Primary Leaching:

[0124] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 20 C. and the leaching time is 60 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 20 C. for 24 h to obtain an oxide Ta.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 6 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 15% in excess of hydrochloric acid required by a reaction theory, and

[0125] The oxide Ta.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 10% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0126] Step 3, Performing Multi-Stage Deep Reduction:

[0127] Uniformly mixing the oxide Ta.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 20 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 800 C., performing secondary deep reduction for 3 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: Ta.sub.xO:Ca=1:1.5; and

[0128] Step 4, Performing Secondary Leaching:

[0129] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 30 C. for 15 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 25 C. for 24 h under a vacuum condition to obtain low-oxygen tantalum powder, wherein the molar concentration of hydrochloric acid is 3 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 25% in excess of hydrochloric acid required by a reaction theory; and

[0130] The low-oxygen tantalum powder comprises the following ingredients in percentage by mass: 99.1% of Ta, 0.45% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 22 m.

Embodiment 8

[0131] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0132] Step 1, Performing Self-Propagating Reaction:

[0133] Placing tantalum oxide powder in a drying oven, drying the tantalum oxide powder at the temperature of 100-150 C. for 24 h to obtain dried tantalum oxide powder, mixing the dried tantalum oxide powder with the magnesium powder according to a molar ratio of Ta.sub.2O.sub.5 to Mg being 1 to 3.2 to obtain mixed materials, pressing the mixed materials at 40 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 600 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0134] Step 2, Performing Primary Leaching:

[0135] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 24 C. and the leaching time is 90 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 20 C. for 24 h to obtain an oxide Ta.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 3 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 15% in excess of hydrochloric acid required by a reaction theory, and

[0136] the oxide Ta.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 10% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15-m;

[0137] Step 3, Performing Multi-Stage Deep Reduction:

[0138] Uniformly mixing the oxide Ta.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 10 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 900 C., performing secondary deep reduction for 3 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: Ta.sub.xO:Ca=1:2; and

[0139] Step 4, Performing Secondary Leaching:

[0140] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 20 C. for 30 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 20 C. for 24 h under a vacuum condition to obtain low-oxygen tantalum powder, wherein the molar concentration of hydrochloric acid is 2 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 20% in excess of hydrochloric acid required by a reaction theory; and

[0141] The low-oxygen tantalum powder comprises the following ingredients in percentage by mass: 99.3% of Ta, 0.25% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 34 m.

Embodiment 9

[0142] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0143] Step 1, Performing Self-Propagating Reaction:

[0144] Placing tantalum oxide powder in a drying oven, drying the tantalum oxide powder at the temperature of 100-150 C. for 24 h to obtain dried tantalum oxide powder, mixing the dried tantalum oxide powder with the magnesium powder according to a molar ratio of Ta.sub.2O.sub.5 to Mg being 1 to 2.8 to obtain mixed materials, pressing the mixed materials at 20 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 650 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0145] Step 2, Performing Primary Leaching:

[0146] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 24 C. and the leaching time is 120 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 20 C. for 24 h to obtain an oxide Ta.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 1 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 30% in excess of hydrochloric acid required by a reaction theory, and

[0147] The oxide Ta.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 20% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0148] Step 3, Performing Multi-Stage Deep Reduction:

[0149] Uniformly mixing the oxide Ta.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 5 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 1000 C., performing secondary deep reduction for 2 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: Ta.sub.xO:Ca=1:2.5; and

[0150] Step 4, Performing Secondary Leaching:

[0151] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 20 C. for 30 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 20 C. for 24 h under a vacuum condition to obtain low-oxygen tantalum powder, wherein the molar concentration of hydrochloric acid is 6 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 5% in excess of hydrochloric acid required by a reaction theory; and

[0152] The low-oxygen tantalum powder comprises the following ingredients in percentage by mass: 99.5% of Ta, 0.25% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 44 m.

Embodiment 10

[0153] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0154] Step 1, Performing Self-Propagating Reaction:

[0155] Placing niobium oxide powder in a drying oven, drying the niobium oxide powder at the temperature of 100-150 C. for 24 h to obtain dried niobium oxide powder, mixing the dried niobium oxide powder with the magnesium powder according to a molar ratio of Nb.sub.2O.sub.5 to Mg being 1 to 3 to obtain mixed materials, pressing the mixed materials at 10 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 580 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0156] Step 2, Performing Primary Leaching:

[0157] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 24 C. and the leaching time is 120 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 20 C. for 24 h to obtain an oxide Nb.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 1 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 30% in excess of hydrochloric acid required by a reaction theory, and

[0158] The oxide Nb.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 5% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0159] Step 3, Performing Multi-Stage Deep Reduction:

[0160] Uniformly mixing the oxide Nb.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 5 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 1000 C., performing secondary deep reduction for 3 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: Nb.sub.xO:Ca=1:2.2; and

[0161] Step 4, Performing Secondary Leaching:

[0162] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 20 C. for 30 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 30 C. for 24 h under a vacuum condition to obtain low-oxygen niobium powder, wherein the molar concentration of hydrochloric acid is 1 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 20% in excess of hydrochloric acid required by a reaction theory; and

[0163] The low-oxygen niobium powder comprises the following ingredients in percentage by mass: 99.5% of Nb, 0.16% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 42 m.

Embodiment 11

[0164] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0165] Step 1, Performing Self-Propagating Reaction:

[0166] Placing niobium oxide powder in a drying oven, drying the niobium oxide powder at the temperature of 100-150 C. for 24 h to obtain dried niobium oxide powder, mixing the dried niobium oxide powder with the magnesium powder according to a molar ratio of Nb.sub.2O.sub.5 to Mg being 1 to 2.8 to obtain mixed materials, pressing the mixed materials at 30 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 700 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0167] Step 2, Performing Primary Leaching:

[0168] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 24 C. and the leaching time is 90 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 20 C. for 24 h to obtain an oxide Nb.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 3 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 30% in excess of hydrochloric acid required by a reaction theory, and

[0169] The oxide Nb.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 7% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0170] Step 3, Performing Multi-Stage Deep Reduction:

[0171] Uniformly mixing the oxide Nb.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 5 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 900 C., performing secondary deep reduction for 3 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: Nb.sub.xO:Ca=1:2; and

[0172] Step 4, Performing Secondary Leaching:

[0173] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 20 C. for 90 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 25 C. for 24 h under a vacuum condition to obtain low-oxygen niobium powder, wherein the molar concentration of hydrochloric acid is 2 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 20% in excess of hydrochloric acid required by a reaction theory; and

[0174] The low-oxygen niobium powder comprises the following ingredients in percentage by mass: 99.2% of Nb, 0.41% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 46 m.

Embodiment 12

[0175] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0176] Step 1, Performing Self-Propagating Reaction:

[0177] Placing niobium oxide powder in a drying oven, drying the niobium oxide powder at the temperature of 100-150 C. for 24 h to obtain dried niobium oxide powder, mixing the dried niobium oxide powder with the magnesium powder according to a molar ratio of Nb.sub.2O.sub.5 to Mg being 1 to 3.1 to obtain mixed materials, pressing the mixed materials at 50 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 700 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0178] Step 2, Performing Primary Leaching:

[0179] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 24 C. and the leaching time is 80 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 20 C. for 24 h to obtain an oxide Nb.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 4 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 30% in excess of hydrochloric acid required by a reaction theory, and

[0180] The oxide Nb.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 18% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 jam;

[0181] Step 3, Performing Multi-Stage Deep Reduction:

[0182] Uniformly mixing the oxide Nb.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 5 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 900 C., performing secondary deep reduction for 3 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: Nb.sub.xO:Ca=1:3; and

[0183] Step 4, Performing Secondary Leaching:

[0184] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 30 C. for 15 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 20 C. for 24 h under a vacuum condition to obtain low-oxygen niobium powder, wherein the molar concentration of hydrochloric acid is 3 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 20% in excess of hydrochloric acid required by a reaction theory; and

[0185] The low-oxygen niobium powder comprises the following ingredients in percentage by mass: 99.3% of Nb, 0.22% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 51 m.

Embodiment 13

[0186] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0187] Step 1, Performing Self-Propagating Reaction:

[0188] Placing vanadium oxide powder in a drying oven, drying the vanadium oxide powder at the temperature of 100-150 C. for 24 h to obtain dried vanadium oxide powder, mixing the dried vanadium oxide powder with the magnesium powder according to a molar ratio of V.sub.2O.sub.5 to Mg being 1 to 3 to obtain mixed materials, pressing the mixed materials at 10 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 500 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0189] Step 2, Performing Primary Leaching:

[0190] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 24 C. and the leaching time is 120 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 25 C. for 24 h to obtain an oxide V.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 1 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 40% in excess of hydrochloric acid required by a reaction theory, and

[0191] The oxide V.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 6% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0192] Step 3, Performing Multi-Stage Deep Reduction:

[0193] Uniformly mixing the oxide V.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 5 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 1000 C., performing secondary deep reduction for 3 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: V.sub.xO:Ca=1:2.2; and

[0194] Step 4, Performing Secondary Leaching:

[0195] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 30 C. for 30 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 20 C. for 24 h under a vacuum condition to obtain low-oxygen vanadium powder, wherein the molar concentration of hydrochloric acid is 1 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 30% in excess of hydrochloric acid required by a reaction theory; and

[0196] The low-oxygen vanadium powder comprises the following ingredients in percentage by mass: 99.5% of V, 0.11% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 42 m.

Embodiment 14

[0197] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0198] Step 1, Performing Self-Propagating Reaction:

[0199] Placing vanadium oxide powder in a drying oven, drying the vanadium oxide powder at the temperature of 100-150 C. for 24 h to obtain dried vanadium oxide powder, mixing the dried vanadium oxide powder with the magnesium powder according to a molar ratio of V.sub.2O.sub.5 to Mg being 1 to 2.7 to obtain mixed materials, pressing the mixed materials at 30 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 750 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0200] Step 2, Performing Primary Leaching:

[0201] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 25 C. and the leaching time is 90 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 20 C. for 24 h to obtain an oxide V.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 3 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 40% in excess of hydrochloric acid required by a reaction theory, and

[0202] The oxide V.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 8% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0203] Step 3, Performing Multi-Stage Deep Reduction:

[0204] Uniformly mixing the oxide V.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 5 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 900 C., performing secondary deep reduction for 3 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: V.sub.xO:Ca=1:2; and

[0205] Step 4, Performing Secondary Leaching:

[0206] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 30 C. for 20 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 25 C. for 24 h under a vacuum condition to obtain low-oxygen vanadium powder, wherein the molar concentration of hydrochloric acid is 2 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 30% in excess of hydrochloric acid required by a reaction theory; and

[0207] The low-oxygen vanadium powder comprises the following ingredients in percentage by mass: 99.2% of V, 0.41% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 46 km.

Embodiment 15

[0208] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0209] Step 1, Performing Self-Propagating Reaction:

[0210] Placing vanadium oxide powder in a drying oven, drying the vanadium oxide powder at the temperature of 100-150 C. for 24 h to obtain dried vanadium oxide powder, mixing the dried vanadium oxide powder with the magnesium powder according to a molar ratio of V.sub.2O.sub.5 to Mg being 1 to 2.8 to obtain mixed materials, pressing the mixed materials at 50 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 550 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0211] Step 2, Performing Primary Leaching:

[0212] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 25 C. and the leaching time is 80 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 20 C. for 24 h to obtain an oxide V.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 4 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 40% in excess of hydrochloric acid required by a reaction theory, and

[0213] The oxide V.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 12% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0214] Step 3, Performing Multi-Stage Deep Reduction:

[0215] Uniformly mixing the oxide V.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 5 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 900 C., performing secondary deep reduction for 3 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: V.sub.xO:Ca=1:3; and

[0216] Step 4, Performing Secondary Leaching:

[0217] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 30 C. for 15 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 25 C. for 24 h under a vacuum condition to obtain low-oxygen vanadium powder, wherein the molar concentration of hydrochloric acid is 3 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 30% in excess of hydrochloric acid required by a reaction theory; and

[0218] The low-oxygen vanadium powder comprises the following ingredients in percentage by mass: 99.2% of V, 0.22% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 51 m.

Embodiment 16

[0219] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0220] Step 1, Performing Self-Propagating Reaction:

[0221] Placing hafnium oxide powder in a drying oven, drying the hafnium oxide powder at the temperature of 100-150 C. for 24 h to obtain dried hafnium oxide powder, mixing the dried hafnium oxide powder with the magnesium powder according to a molar ratio of HfO.sub.2 to Mg being 1 to 1 to obtain mixed materials, pressing the mixed materials at 30 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 600 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0222] Step 2, Performing Primary Leaching:

[0223] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 20 C. and the leaching time is 180 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 20 C. for 24 h to obtain an oxide Hf.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 1 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 40% in excess of hydrochloric acid required by a reaction theory, and

[0224] The oxide Hf.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 15% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 jam;

[0225] Step 3, Performing Multi-Stage Deep Reduction:

[0226] Uniformly mixing the oxide Hf.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 10 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 1000 C., performing secondary deep reduction for 2 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: Hf.sub.fO:Ca=1:1.6; and

[0227] Step 4, Performing Secondary Leaching:

[0228] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 30 C. for 30 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 25 C. for 24 h under a vacuum condition to obtain low-oxygen hafnium powder, wherein the molar concentration of hydrochloric acid is 1 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 30% in excess of hydrochloric acid required by a reaction theory; and

[0229] The low-oxygen hafnium powder comprises the following ingredients in percentage by mass: 99.4% of Hf, 0.12% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 5 m.

Embodiment 17

[0230] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0231] Step 1, Performing Self-Propagating Reaction:

[0232] Placing hafnium oxide powder in a drying oven, drying the hafnium oxide powder at the temperature of 100-150 C. for 24 h to obtain dried hafnium oxide powder, mixing the dried hafnium oxide powder with the magnesium powder according to a molar ratio of HfO.sub.2 to Mg being 1 to 1.2 to obtain mixed materials, pressing the mixed materials at 10 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 600 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0233] Step 2, Performing Primary Leaching:

[0234] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 20 C. and the leaching time is 120 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 24 C. for 24 h to obtain an oxide Hf.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 2 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 40% in excess of hydrochloric acid required by a reaction theory, and

[0235] The oxide Hf.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 15% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0236] Step 3, Performing Multi-Stage Deep Reduction:

[0237] Uniformly mixing the oxide Hf.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 15 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 900 C., performing secondary deep reduction for 3 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: Hf.sub.xO:Ca=1:2; and

[0238] Step 4, Performing Secondary Leaching:

[0239] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 30 C. for 20 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 30 C. for 24 h under a vacuum condition to obtain low-oxygen hafnium powder, wherein the molar concentration of hydrochloric acid is 2 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 20% in excess of hydrochloric acid required by a reaction theory; and

[0240] The low-oxygen hafnium powder comprises the following ingredients in percentage by mass: 99.2% of Hf, 0.27% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 40 m.

Embodiment 18

[0241] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0242] Step 1, Performing Self-Propagating Reaction:

[0243] Placing hafnium oxide powder in a drying oven, drying the hafnium oxide powder at the temperature of 100-150 C. for 24 h to obtain dried hafnium oxide powder, mixing the dried hafnium oxide powder with the magnesium powder according to a molar ratio of HfO.sub.2 to Mg being 1 to 0.9 to obtain mixed materials, pressing the mixed materials at 50 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 650 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0244] Step 2, Performing Primary Leaching:

[0245] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 30 C. and the leaching time is 60 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 20 C. for 24 h to obtain an oxide Hf.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 6 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 10% in excess of hydrochloric acid required by a reaction theory, and

[0246] The oxide Hf.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 18% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0247] Step 3, Performing Multi-Stage Deep Reduction:

[0248] Uniformly mixing the oxide Hf.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 5 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 1200 C., performing secondary deep reduction for 1 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: Hf.sub.xO:Ca=1:1.8; and

[0249] Step 4, Performing Secondary Leaching:

[0250] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 30 C. for 15 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 24DEG C. for 24 h under a vacuum condition to obtain low-oxygen hafnium powder, wherein the molar concentration of hydrochloric acid is 3 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 20% in excess of hydrochloric acid required by a reaction theory; and

[0251] The low-oxygen hafnium powder comprises the following ingredients in percentage by mass: 99.4% of Hf, 0.21% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 60 m.

Embodiment 19

[0252] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0253] Step 1, Performing Self-Propagating Reaction:

[0254] Placing zirconium oxide powder in a drying oven, drying the zirconium oxide powder at the temperature of 100-150 C. for 24 h to obtain dried zirconium oxide powder, mixing the dried zirconium oxide powder with the magnesium powder according to a molar ratio of ZrO.sub.2 to Mg being 1 to 1 to obtain mixed materials, pressing the mixed materials at 30 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 650 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0255] Step 2, Performing Primary Leaching:

[0256] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 30 C. and the leaching time is 180 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 22 C. for 24 h to obtain an oxide Zr.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 1 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 40% in excess of hydrochloric acid required by a reaction theory, and

[0257] The oxide Zr.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 12% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0258] Step 3, Performing Multi-Stage Deep Reduction:

[0259] Uniformly mixing the oxide Zr.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 10 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 1000 C., performing secondary deep reduction for 2 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: Zr.sub.xO:Ca=1:1.5; and

[0260] Step 4, Performing Secondary Leaching:

[0261] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 30 C. for 30 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 24 C. for 24 h under a vacuum condition to obtain low-oxygen zirconium powder, wherein the molar concentration of hydrochloric acid is 1 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 30% in excess of hydrochloric acid required by a reaction theory; and

[0262] The low-oxygen zirconium powder comprises the following ingredients in percentage by mass: 99.5% of Zr, 0.12% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 36 m.

Embodiment 20

[0263] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0264] Step 1, Performing Self-Propagating Reaction:

[0265] Placing zirconium oxide powder in a drying oven, drying the zirconium oxide powder at the temperature of 100-150 C. for 24 h to obtain dried zirconium oxide powder, mixing the dried zirconium oxide powder with the magnesium powder according to a molar ratio of ZrO.sub.2 to Mg being 1 to 1.2 to obtain mixed materials, directly adding the mixed materials to the self-propagating reaction furnace, initiating the self-propagating reaction in a entire heating mode, controlling the temperature at 550 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0266] Step 2, Performing Primary Leaching:

[0267] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 30 C. and the leaching time is 120 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 20 C. for 24 h to obtain an oxide Zr.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 2 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 26% in excess of hydrochloric acid required by a reaction theory, and

[0268] The oxide Zr.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 5-20% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0269] Step 3, Performing Multi-Stage Deep Reduction:

[0270] Uniformly mixing the oxide Zr.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 20 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 900 C., performing secondary deep reduction for 3 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: Zr.sub.xO:Ca=1:2; and

[0271] Step 4, Performing Secondary Leaching:

[0272] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 30 C. for 20 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 22 C. for 24 h under a vacuum condition to obtain low-oxygen zirconium powder, wherein the molar concentration of hydrochloric acid is 2 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 15% in excess of hydrochloric acid required by a reaction theory; and

[0273] The low-oxygen zirconium powder comprises the following ingredients in percentage by mass: 99.1% of Zr, 0.35% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 40 m.

Embodiment 21

[0274] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0275] Step 1, Performing Self-Propagating Reaction:

[0276] Placing zirconium oxide powder in a drying oven, drying the zirconium oxide powder at the temperature of 100-150 C. for 24 h to obtain dried zirconium oxide powder, mixing the dried zirconium oxide powder with the magnesium powder according to a molar ratio of ZrO.sub.2 to Mg being 1 to 0.8 to obtain mixed materials, pressing the mixed materials at 50 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 570 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0277] Step 2, Performing Primary Leaching:

[0278] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 30 C. and the leaching time is 60 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 30 C. for 24 h to obtain an oxide Zr.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 6 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 12% in excess of hydrochloric acid required by a reaction theory, and

[0279] The oxide Zr.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 15% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 jam;

[0280] Step 3, Performing Multi-Stage Deep Reduction:

[0281] Uniformly mixing the oxide Zr.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 5 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 1100 C., performing secondary deep reduction for 2 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: Zr.sub.xO:Ca=1:1.8; and

[0282] Step 4, Performing Secondary Leaching:

[0283] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 30 C. for 15 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 24 C. for 24 h under a vacuum condition to obtain low-oxygen zirconium powder, wherein the molar concentration of hydrochloric acid is 3 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 25% in excess of hydrochloric acid required by a reaction theory; and

[0284] The low-oxygen zirconium powder comprises the following ingredients in percentage by mass: 99.3% of Zr, 0.21% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 47 m.

Embodiment 22

[0285] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0286] Step 1, Performing Self-Propagating Reaction:

[0287] Placing rhenium oxide powder in a drying oven, drying the rhenium oxide powder at the temperature of 100-150 C. for 24 h to obtain dried rhenium oxide powder, mixing the dried rhenium oxide powder with the magnesium powder according to a molar ratio of Re.sub.2O.sub.7 to Mg being 1 to 3 to obtain mixed materials, pressing the mixed materials at 40 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 650 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0288] Step 2, Performing Primary Leaching:

[0289] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 30 C. and the leaching time is 180 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 20 C. for 24 h to obtain an oxide Re.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 1 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 12% in excess of hydrochloric acid required by a reaction theory, and

[0290] The oxide Re.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 5% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0291] Step 3, Performing Multi-Stage Deep Reduction:

[0292] Uniformly mixing the oxide Re.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 10 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 700 C., performing secondary deep reduction for 6 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: Re.sub.xO:Ca=1:1.5; and

[0293] Step 4, Performing Secondary Leaching:

[0294] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 30 C. for 30 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 20 C. for 24 h under a vacuum condition to obtain low-oxygen rhenium powder, wherein the molar concentration of hydrochloric acid is 2 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 15% in excess of hydrochloric acid required by a reaction theory; and

[0295] The low-oxygen rhenium powder comprises the following ingredients in percentage by mass: 99.5% of Re, 0.12% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 37 m.

Embodiment 23

[0296] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0297] Step 1, Performing Self-Propagating Reaction:

[0298] Placing rhenium oxide powder in a drying oven, drying the rhenium oxide powder at the temperature of 100-150 C. for 24 h to obtain dried rhenium oxide powder, mixing the dried rhenium oxide powder with the magnesium powder according to a molar ratio of Re.sub.2O.sub.7 to Mg being 1 to 2.9 to obtain mixed materials, pressing the mixed materials at 30 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 650 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0299] Step 2, Performing Primary Leaching:

[0300] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 30 C. and the leaching time is 100 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 30 C. for 24 h to obtain an oxide Re.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 4 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 30% in excess of hydrochloric acid required by a reaction theory, and

[0301] The oxide Re.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 12% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0302] Step 3, Performing Multi-Stage Deep Reduction:

[0303] Uniformly mixing the oxide Re.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 2 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 900 C., performing secondary deep reduction for 4 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: Re.sub.xO:Ca=1:2; and

[0304] Step 4, Performing Secondary Leaching:

[0305] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 30 C. for 30 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 26 C. for 24 h under a vacuum condition to obtain low-oxygen rhenium powder, wherein the molar concentration of hydrochloric acid is 2 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 25% in excess of hydrochloric acid required by a reaction theory; and

[0306] The low-oxygen hafnium powder comprises the following ingredients in percentage by mass: 99.2% of Re, 0.25% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 45 m.

Embodiment 24

[0307] The method for preparing high-melting-point metal powder through multi-stage deep reduction provided by the invention comprises the following steps:

[0308] Step 1, Performing Self-Propagating Reaction:

[0309] Placing rhenium oxide powder in a drying oven, drying the rhenium oxide powder at the temperature of 100-150 C. for 24 h to obtain dried rhenium oxide powder, mixing the dried rhenium oxide powder with the magnesium powder according to a molar ratio of Re.sub.2O.sub.7 to Mg being 1 to 3.3 to obtain mixed materials, pressing the mixed materials at 40 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace, initiating the self-propagating reaction in a local ignition mode, controlling the temperature at 650 C. and performing cooling to obtain an intermediate product in which a low-valence oxide Me.sub.xO of high-melting-point metal is dispersed in an MgO matrix, wherein the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio, and x is 0.2-1;

[0310] Step 2, Performing Primary Leaching:

[0311] Placing the intermediate product in which the low-valence oxide Me.sub.xO of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution under the condition that the leaching temperature is 30 C. and the leaching time is 80 min to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product in a dynamic washing mode, and performing vacuum drying at 30 C. for 24 h to obtain an oxide Re.sub.xO precursor of the low-valence high-melting-point metal, wherein the molar concentration of hydrochloric acid is 6 mol/L, the diluted hydrochloric acid and the intermediate product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 12% in excess of hydrochloric acid required by a reaction theory, and

[0312] The oxide Re.sub.xO precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 20% of O, smaller than or equal to 0.5% of the inevitable impurities and the balance of the high-melting-point metal, wherein the particle size is 0.8-15 m;

[0313] Step 3, Performing Multi-Stage Deep Reduction:

[0314] Uniformly mixing the oxide Re.sub.xO precursor of the low-valence high-melting-point metal with calcium powder, performing pressing at 15 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating under the condition that the vacuum degree is smaller than or equal to 10 Pa to 1100 C., performing secondary deep reduction for 2 h, obtaining a block billet after secondary deep reduction, and cooling the block billet along with the furnace to obtain a deep reduction product, wherein the molar ratio is described as follows: Re.sub.xO:Ca=1:2; and

[0315] Step 4, Performing Secondary Leaching:

[0316] Placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution at the temperature of 30 C. for 30 min to obtain filtrate and filter residues, removing the filtrate, washing the filter residues in a dynamic washing mode and drying the washed filter residues at the temperature of 26 C. for 24 h under a vacuum condition to obtain low-oxygen rhenium powder, wherein the molar concentration of hydrochloric acid is 3 mol/L, and diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that the adding amount of diluted hydrochloric acid is 25% in excess of hydrochloric acid required by a reaction theory; and

[0317] The low-oxygen hafnium powder comprises the following ingredients in percentage by mass: 99.3% of Re, 0.21% of O and the balance of inevitable impurities, and the particle size of the low-oxygen tungsten powder is 47 m.