Method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining

Abstract

The present invention provides a method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining. The method includes the steps of (1) performing aluminothermic self-propagating gradient reduction; (2) performing heat preserving and smelting to obtain an upper layer alumina-based slag and a lower layer alloy melt; (3) jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining; and (4) cooling the refined high-temperature melt to room temperature, and removing an upper layer smelting slag to obtain the ferrovanadium alloys.

Claims

1. A method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining, comprising the following steps: (1) performing the aluminothermic self-propagating gradient reduction in one of the following two manners: a first manner: dividing raw materials of vanadium oxide, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former into 5-8 batches, pouring a first batch of the raw materials into a reaction furnace, igniting magnesium powder from a top of the raw materials to initiate an aluminothermic self-propagating reaction, and sequentially adding other batches of the raw materials until reaction is completed to obtain a melt, wherein an aluminium proportioning amount of each batch of the raw materials is reduced in a gradient manner from 1.15-1.35 times to 0.85-0.65 times a theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, and a total aluminium proportioning amount of the raw materials is 0.94-1.00 times the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction; a second manner: uniformly mixing raw materials of the vanadium oxide, the Fe.sub.2O.sub.3 powder and the slag former to obtain a mixture, adding the mixture into a continuous mixer at an even velocity, adding the aluminium powder into the continuous mixer at a velocity decreasing in a gradient manner at the same time as adding the mixture into the continuous mixer, and continuously introducing uniformly mixed materials comprising the vanadium oxide, the Fe.sub.2O.sub.3 powder, the slag former and the aluminium powder into the reaction furnace for the aluminothermic self-propagating reaction, wherein an entire material mixing process and an entire reaction process are performed continuously until all materials react completely to obtain the melt, wherein the aluminium proportioning amount of the continuous raw materials introduced into the reaction furnace is gradiently reduced from 1.15-1.35 times to 0.85-0.65 times the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, wherein a number n of gradient changes of the aluminium proportioning amount in the entire process satisfies a relational expression: n=(b-c)/a, wherein b represents a highest aluminium proportioning amount, c represents a lowest aluminium proportioning amount, a represents a gradient change coefficient of the aluminium proportioning amount, and a is greater than 0 and smaller than or equal to 0.04, and the total aluminium proportioning amount of the raw materials is 0.094-1.00 times the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction; (2) performing heat preservation and smelting of the melt through electromagnetic induction heating to obtain an upper layer alumina-based slag and a lower layer alloy melt; (3) jetting refinement slags into the lower layer alloy melt, and performing stirring and slag washing refinement; and (4) cooling the refined high temperature melt to room temperature, and removing an upper layer smelting slag to obtain the ferrovanadium alloys.

2. The method of claim 1, wherein a mass ratio of the raw materials of the vanadium oxide to the Fe.sub.2O.sub.3 powder to the aluminium powder to the slag former in step (1) is 1.0:(0.2-1.49):(0.56-1.00):(0.82-1.95), and particle sizes thereof respectively meet the following conditions: a particle size of the vanadium oxide is smaller than or equal to 5 mm, a particle size of the Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, a particle size of the aluminium powder is smaller than or equal to 5 mm, and a particle size of the slag former is smaller than or equal to 0.2 mm.

3. The method of claim 1, wherein in step (1), a weight of the first batch of the raw materials is 10-30% of a total weight of the raw materials.

4. The method of claim 1, wherein control parameters of the heat preservation and smelting in step (2) are as follows: an electromagnetic induction frequency is greater than or equal to 1000 Hz, a smelting temperature is 1700-1800° C., and a heat preserving time is 5-15 min.

5. The method of claim 1, wherein the refinement slags in step (3) is one of the following two types: (1) 10-25% of CaF.sub.2 and a balance of CaO by mass; and (2) 10-25% of CaF.sub.2, 5-10% of Na.sub.2O and a balance of CaO by mass.

6. The method of claim 1, wherein control parameters of the stirring and slag washing refinements in step (3) are as follows: an eccentric stirring is adopted, an eccentricity ratio is 0.2-0.4, an addition amount of the refinement slags is 2-8% of total raw materials and inert gas with purity being greater than or equal to 99.95% is used as carrier gas, a stirring speed is 50-150 rpm, a refining temperature is 1700-1800° C., and a refining time is 10-30 min.

7. The method of claim 1, wherein the ferrovanadium alloys comprise chemical components in percentage by mass of 35.0-80.0% of V, Al being smaller than or equal to 1.5%, Si being smaller than or equal to 1.0%, O being smaller than or equal to 1.0%, and a balance of Fe.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(1) In the description of the prevent invention, it should be noted that the conventional conditions or the conditions recommended by manufacturers shall prevail in the embodiment that no specific conditions are specified in the embodiments. Manufacturers of used reagents or instruments are not specified, and commercially available conventional products shall be used.

(2) The present invention will be further detailed below in combination with embodiments. The description of the present invention is not intended to be limitation.

Embodiment 1

(3) The method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining comprises the following steps:

(4) (1) Aluminothermic self-propagating gradient reduction

(5) Preparing the raw materials in mass ratio of the raw materials of V.sub.2O.sub.5, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former CaO being 1.0 to 0.8 to 0.76 to 0.99, wherein the particle size meets the condition that the particle size of the vanadium oxide is smaller than or equal to 5 mm, the particle size of Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, the particle size of the aluminium powder is smaller than or equal to 5 mm, and the particle size of the slag former is smaller than or equal to 0.2 mm; dividing the materials into 5 batches, wherein the aluminium proportioning amount of each batch of the materials is gradually 1.20, 1.05, 1.00, 0.90 and 0.85 time of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, the total aluminium proportioning amount of the raw materials is 0.98 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, and the weight of the first batch of the materials is 20% of that of the total materials; adding the first batch of the materials to a reaction furnace, pouring the first batch of materials into the reaction furnace, performing igniting with magnesium powder from the top of the materials to initiate the self-propagating reaction, and sequentially adding other batches of the materials till complete reaction to obtain high-temperature melt;

(6) (2) Performing heat preserving and smelting on the high-temperature melt through electromagnetic induction heating to realize metal-slag separation to obtain an upper layer alumina-based slag and a lower layer alloy melt, wherein the control parameters are as follows: the electromagnetic induction frequency is greater than or equal to 1000 Hz, the smelting temperature is 1800° C., and the heat preserving time is 15 min;

(7) (3) Removing 90% of upper-layer aluminium oxide based melt slags, jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining, wherein the refining slags consist of the components in mass ratio of 10% of CaF.sub.2 and 90% of CaO, and the control parameters are as follows: the addition amount of the refining slags is 2% of total raw materials, argon gas with purity being greater than or equal to 99.95°% is used as carrier gas, the eccentric stirring speed is 50 rpm, the eccentric rate is 0.23, the refining temperature is 1800° C., and the refining time is 10 min; and

(8) (4) Cooling the refined high-temperature melt to room temperature, and removing the upper layer smelting slag to obtain the ferrovanadium alloys.

(9) Furthermore, the prepared ferrovanadium alloys in the embodiment consist of the following chemical components in percentages by mass: 49.1% of V, 0.2% of Si, 0.8% of Al, 0.6% of O, and the balance of Fe.

Embodiment 2

(10) The method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining comprises the following steps:

(11) (1) Aluminothermic self-propagating gradient reduction

(12) Preparing the raw materials in mass ratio of the raw materials of V.sub.2O.sub.5, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former CaO being 1.0 to 0.94 to 0.79 to 1.15, wherein the particle size meets the condition that the particle size of the vanadium oxide is smaller than or equal to 5 mm, the particle size of Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, the particle size of the aluminium powder is smaller than or equal to 5 mm, and the article size of the slag former is smaller than or equal to 0.2 mm; dividing the materials into 6 batches, wherein the aluminium proportioning amount of each batch of the materials is gradually 1.20, 1.10, 0.95, 0.90, 0.85 and 0.80 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, the total aluminium proportioning amount of the raw materials is 0.98 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, and the weight of the first batch of the materials is 28.6% of that of the total materials; adding the first batch of the materials to a reaction furnace, pouring the first batch of materials into the reaction furnace, performing igniting with magnesium powder from the top of the materials to initiate the self-propagating reaction, and sequentially adding other batches of the materials till complete reaction to obtain high-temperature melt;

(13) (2) Performing heat preserving and smelting on the high-temperature melt through electromagnetic induction heating to realize metal-slag separation to obtain an upper layer alumina-based slag and a lower layer alloy melt, wherein the control parameters are as follows: the electromagnetic induction frequency is greater than or equal to 1000 Hz, the smelting temperature is 1750° C., and the heat preserving time is 10 min;

(14) (3) Removing 90% of upper-layer aluminium oxide based melt slags, jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining, wherein the refining slags consist of the components in mass ratio of 20% of CaF.sub.2 and 80% of CaO, and the control parameters are as follows: the addition amount of the refining slags is 5% of total raw materials, argon gas with purity being greater than or equal to 99.95% is used as carrier gas, the eccentric stirring speed is 100 rpm, the eccentric rate is 0.28, the refining temperature is 1750° C., and the refining time is 20 min; and

(15) (4) Cooling the refined high-temperature melt to room temperature, and removing the upper layer smelting slag to obtain the ferrovanadium alloys.

(16) Furthermore, the prepared ferrovanadium alloys in the embodiment consist of the following chemical components in percentages by mass: 48.7% of V, 0.4% of Si, 0.7% of Al, 0.6% of O, and the balance of Fe.

Embodiment 3

(17) The method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining specially comprises the following steps:

(18) (1) Aluminothermic self-propagating gradient reduction

(19) Preparing the raw materials in mass ratio of the raw materials of V.sub.2O.sub.3, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former CaO being 1.0 to 1.06 to 0.84 to 1.54, wherein the particle size meets that the particle size of the vanadium oxide is smaller than or equal to 5 mm, the particle size of Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, the particle size of the aluminium powder is smaller than or equal to 5 mm, and the particle size of the slag former is smaller than or equal to 0.2 mm; dividing the materials into 8 batches, wherein the aluminium proportioning amount of each batch of the materials is gradually 1.20, 1.1, 1.0, 0.95, 0.925, 0.90, 0.875 and 0.85 time of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, the total aluminium proportioning amount of the raw materials is 0.98 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, and the weight of the first batch of the materials is 22.2% of that of the total materials; adding the first batch of the materials to a reaction furnace, pouring the first batch of materials into the reaction furnace, performing igniting with magnesium powder from the top of the materials to initiate the self-propagating reaction, and sequentially adding other batches of the materials till complete reaction to obtain high-temperature melt;

(20) (2) Performing heat preserving and smelting on the high-temperature melt through electromagnetic induction heating to realize metal-slag separation to obtain an upper layer alumina-based slag and a lower layer alloy melt, wherein the control parameters are as follows: the electromagnetic induction frequency is greater than or equal to 1000 Hz, the smelting temperature is 1700° C., and the heat preserving time is 5 min;

(21) (3) Removing 90% of upper-layer aluminium oxide based melt slags, jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining, wherein the refining slags consist of the components in mass ratio of 25% of CaF.sub.2 and 75% of CaO, and the control parameters are as follows: the addition amount of the refining slags is 7% of total raw materials, argon gas with purity being greater than or equal to 99.95% is used as carrier gas, the eccentric stirring speed is 150 rpm, the eccentric rate is 0.4, the refining temperature is 1700° C., and the refining time is 30 min; and

(22) (4) Cooling the refined high-temperature melt to room temperature, and removing the upper layer smelting slag to obtain the ferrovanadium alloys.

(23) Furthermore, the prepared ferrovanadium alloys in the embodiment consist of the following chemical components in percentages by mass: 47.0% of V, 0.2% of Si, 0.41% of Al, 0.45% of O, and the balance of Fe.

Embodiment 4

(24) The method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining specially comprises the following steps:

(25) (1) Aluminothermic self-propagating gradient reduction

(26) Preparing the raw materials in mass ratio of the raw materials of V.sub.2O.sub.3, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former CaO being 1.0 to 1.24 to 0.86 to 1.62, wherein the particle size meets that the particle size of the vanadium oxide is smaller than or equal to 5 mm, the particle size of Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, the particle size of the aluminium powder is smaller than or equal to 5 mm, and the particle size of the slag former is smaller than or equal to 0.2 mm; uniformly mixing the raw materials of the V.sub.2O.sub.3, the Fe.sub.2O.sub.3 powder and the slag former to obtain a mixture, adding the mixture into a continuous mixer at an even velocity, adding the aluminium powder into the continuous mixer at a gradiently decreased velocity at the same time, and continuously introducing the uniformly mixed materials into the reaction furnace for the aluminothermic self-propagating reaction, wherein the entire material mixing process and the entire reaction process are performed continuously until all materials react completely to obtain the high-temperature melt, the aluminium proportioning amount of continuous materials introduced into the reaction furnace is gradiently reduced from 1.3 times to 0.68 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, the number a of gradient changes is 0.004, the number of gradient changes of the aluminium proportioning amount in the entire process is 155 times, and the total aluminium proportioning amount of the raw materials is 0.98 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction;

(27) (2) Performing heat preserving and smelting on the high-temperature melt through electromagnetic induction heating to realize metal-slag separation to obtain an upper layer alumina-based slag and a lower layer alloy melt, wherein the control parameters are as follows: the electromagnetic induction frequency is greater than or equal to 1000 Hz, the smelting temperature is 1750° C., and the heat preserving time is 10 min;

(28) (3) Removing 90% of upper-layer aluminium oxide based melt slags, jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining, wherein the refining slags consist of the components in mass ratio of 10% of CaF.sub.2, 85% of CaO and 5% of Na.sub.2O, and the control parameters are as follows: the addition amount of the refining slags is 5% of total raw materials, argon gas with purity being greater than or equal to 99.95% is used as carrier gas, the eccentric stirring speed is 100 rpm, the eccentric rate is 0.2, the refining temperature is 1750° C., and the refining time is 20 min; and

(29) (4) Cooling the refined high-temperature melt to room temperature, and removing the upper layer smelting slag to obtain the ferrovanadium alloys.

(30) Furthermore, the prepared ferrovanadium alloys in the embodiment consist of the following chemical components in percentages by mass: 42.5% of V, 0.6% of Si, 0.70% of Al, 0.56% of O, and the balance of Fe.

Embodiment 5

(31) The method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining specially comprises the following steps:

(32) (1) Aluminothermic self-propagating gradient reduction

(33) Preparing the raw materials in mass ratio of the raw materials of V.sub.2O.sub.5, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former CaO being 1.0 to 1.37 to 0.89 to 1.71, wherein the particle size meets that the particle size of the vanadium oxide is smaller than or equal to 5 mm, the particle size of Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, the particle size of the aluminium powder is smaller than or equal to 5 mm, and the particle size of the slag former is smaller than or equal to 0.2 mm; uniformly mixing the raw materials of the V.sub.2O.sub.5, the Fe.sub.2O.sub.3 powder and the slag former to obtain a mixture, adding the mixture into a continuous mixer at an even velocity, adding the aluminium powder into the continuous mixer at a gradiently decreased velocity at the same time, and continuously introducing the uniformly mixed materials into the reaction furnace for the aluminothermic self-propagating reaction, wherein the entire material mixing process and the entire reaction process are performed continuously until all materials react completely to obtain the high-temperature melt, the aluminium proportioning amount of continuous materials introduced into the reaction furnace is gradiently reduced from 1.26 times to 0.7 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, the number a of gradient changes is 0.002, the number of gradient changes of the aluminium proportioning amount in the entire process is 280 times, and the total aluminium proportioning amount of the raw materials is 0.96 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction;

(34) (2) Performing heat preserving and smelting on the high-temperature melt through electromagnetic induction heating to realize metal-slag separation to obtain an upper layer alumina-based slag and a lower layer alloy melt, wherein the control parameters are as follows: the electromagnetic induction frequency is greater than or equal to 1000 Hz, the smelting temperature is 1700° C., and the heat preserving time is 10 min;

(35) (3) Removing 90% of upper-layer aluminium oxide based melt slags, jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining, wherein the refining slags consist of the components in mass ratio of 10% of CaF.sub.2, 80% of CaO and 10% of Na.sub.2O, and the control parameters are as follows: the addition amount of the refining slags is 4% of total raw materials, argon gas with purity being greater than or equal to 99.95% is used as carrier gas, the eccentric stirring speed is 100 rpm, the eccentric rate is 0.3, the refining temperature is 1700° C., and the refining time is 20 min; and

(36) (4) Cooling the refined high-temperature melt to room temperature, and removing the upper layer smelting slag to obtain the ferrovanadium alloys.

(37) Furthermore, the prepared ferrovanadium alloys in the embodiment consist of the following chemical components in percentages by mass: 40.6% of V, 0.7% of Si, 0.65% of Al, 0.54% of O, and the balance of Fe.

Embodiment 6

(38) The method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining specially comprises the following steps:

(39) (1) Aluminothermic self-propagating gradient reduction

(40) Preparing the raw materials in mass ratio of the raw materials of V.sub.2O.sub.5, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former CaO being 1.0 to 1.39 to 0.92 to 1.54, wherein the particle size meets that the particle size of the vanadium oxide is smaller than or equal to 5 mm, the particle size of Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, the particle size of the aluminium powder is smaller than or equal to 5 mm, and the particle size of the slag former is smaller than or equal to 0.2 mm; uniformly mixing the raw materials of the V.sub.2O.sub.5, the Fe.sub.2O.sub.3 powder and the slag former to obtain a mixture, adding the mixture into a continuous mixer at an even velocity, adding the aluminium powder into the continuous mixer at a gradiently decreased velocity at the same time, and continuously introducing the uniformly mixed materials into the reaction furnace for the aluminothermic self-propagating reaction, wherein the entire material mixing process and the entire reaction process are performed continuously until all materials react completely to obtain the high-temperature melt, the aluminium proportioning amount of continuous materials introduced into the reaction furnace is gradiently reduced from 1.26 times to 0.68 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, the number a of gradient changes is 0.001, the number of gradient changes of the aluminium proportioning amount in the entire process is 580 times, and the total aluminium proportioning amount of the raw materials is 0.94 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction;

(41) (2) Performing heat preserving and smelting on the high-temperature melt through electromagnetic induction heating to realize metal-slag separation to obtain an upper layer alumina-based slag and a lower layer alloy melt, wherein the control parameters are as follows: the electromagnetic induction frequency is greater than or equal to 1000 Hz, the smelting temperature is 1700° C., and the heat preserving time is 15 min;

(42) (3) Removing 90% of upper-layer aluminium oxide based melt slags, jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining, wherein the refining slags consist of the components in mass ratio of 20% of CaF.sub.2, 75% of CaO and 5% of Na.sub.2O, and the control parameters are as follows: the addition amount of the refining slags is 8% of total raw materials, argon gas with purity being greater than or equal to 99.95% is used as carrier gas, the eccentric stirring speed is 100 rpm, the eccentric rate is 0.4, the refining temperature is 1700° C., and the refining time is 30 min; and

(43) (4) Cooling the refined high-temperature melt to room temperature, and removing the upper layer smelting slag to obtain the ferrovanadium alloys.

(44) Furthermore, the prepared ferrovanadium alloys in the embodiment consist of the following chemical components in percentages by mass: 38.6% of V, 0.6% of Si, 0.36% of Al, 0.31% of O, and the balance of Fe.

Embodiment 7

(45) The method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining specially comprises the following steps:

(46) (1) Aluminothermic self-propagating gradient reduction

(47) Preparing the raw materials in mass ratio of the raw materials of V.sub.2O.sub.5, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former CaO being 1.0 to 0.43 to 0.64 to 0.85, wherein the particle size meets that the particle size of the vanadium oxide is smaller than or equal to 5 mm, the particle size of Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, the particle size of the aluminium powder is smaller than or equal to 5 mm, and the particle size of the slag former is smaller than or equal to 0.2 mm; dividing the materials into 5 batches, wherein the aluminium proportioning amount of each batch of the materials is gradually 1.20, 1.05, 1.0, 0.90 and 0.85 time of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, the total aluminium proportioning amount of the raw materials is 0.97 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, and the weight of the first batch of the materials is 20% of that of the total materials; adding the first batch of the materials to a reaction furnace, pouring the first batch of materials into the reaction furnace, performing igniting with magnesium powder from the top of the materials to initiate the self-propagating reaction, and sequentially adding other batches of the materials till complete reaction to obtain high-temperature melt;

(48) (2) Performing heat preserving and smelting on the high-temperature melt through electromagnetic induction heating to realize metal-slag separation to obtain an upper layer alumina-based slag and a lower layer alloy melt, wherein the control parameters are as follows: the electromagnetic induction frequency is greater than or equal to 1000 Hz, the smelting temperature is 1800° C., and the heat preserving time is 15 min;

(49) (3) Removing 90% of upper-layer aluminium oxide based melt slags, jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining, wherein the refining slags consist of the components in mass ratio of 10% of CaF.sub.2 and 90% of CaO, and the control parameters are as follows: the addition amount of the refining slags is 2% of total raw materials, argon gas with purity being greater than or equal to 99.95% is used as carrier gas, the eccentric stirring speed is 50 rpm, the eccentric rate is 0.32, the refining temperature is 1800° C., and the refining time is 10 min; and

(50) (4) Cooling the refined high-temperature melt to room temperature, and removing the upper layer smelting slag to obtain the ferrovanadium alloys.

(51) Furthermore, the prepared ferrovanadium alloys in the embodiment consist of the following chemical components in percentages by mass: 64.2% of V, 0.1% of Si, 0.72% of Al, 0.57% of O, and the balance of Fe.

Embodiment 8

(52) The method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining specially comprises the following steps:

(53) (1) Aluminothermic self-propagating gradient reduction

(54) Preparing the raw materials in mass ratio of the raw materials of V.sub.2O.sub.5, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former CaO being 1.0 to 0.49 to 0.66 to 0.91, wherein the particle size meets that the particle size of the vanadium oxide is smaller than or equal to 5 mm, the particle size of Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, the particle size of the aluminium powder is smaller than or equal to 5 mm, and the particle size of the slag former is smaller than or equal to 0.2 mm; dividing the materials into 6 batches, wherein the aluminium proportioning amount of each batch of the materials is gradually 1.20, 1.1, 0.95, 0.90, 0.85 and 0.80 time of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, the total aluminium proportioning amount of the raw materials is 0.96 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, and the weight of the first batch of the materials is 28.6% of that of the total materials; adding the first batch of the materials to a reaction furnace, pouring the first batch of materials into the reaction furnace, performing igniting with magnesium powder from the top of the materials to initiate the self-propagating reaction, and sequentially adding other batches of the materials till complete reaction to obtain high-temperature melt;

(55) (2) Performing heat preserving and smelting on the high-temperature melt through electromagnetic induction heating to realize metal-slag separation to obtain an upper layer alumina-based slag and a lower layer alloy melt, wherein the control parameters are as follows: the electromagnetic induction frequency is greater than or equal to 1000 Hz, the smelting temperature is 1750° C., and the heat preserving time is 10 min;

(56) (3) Removing 90% of upper-layer aluminium oxide based melt slags, jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining, wherein the refining slags consist of the components in mass ratio of 20% of CaF.sub.2 and 80% of CaO, and the control parameters are as follows: the addition amount of the refining slags is 5% of total raw materials, argon gas with purity being greater than or equal to 99.95% is used as carrier gas, the eccentric stirring speed is 100 rpm, the eccentric rate is 0.35, the refining temperature is 1750° C., and the refining time is 20 min; and

(57) (4) Cooling the refined high-temperature melt to room temperature, and removing the upper layer smelting slag to obtain the ferrovanadium alloys.

(58) Furthermore, the prepared ferrovanadium alloys in the embodiment consists of the following chemical components in percentages by mass: 63.9% of V, 0.4% of Si, 0.63% of Al, 0.54% of O, and the balance of Fe.

Embodiment 9

(59) The method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining specially comprises the following steps:

(60) (1) Aluminothermic self-propagating gradient reduction

(61) Preparing the raw materials in mass ratio of the raw materials of V.sub.2O.sub.5, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former CaO being 1.0 to 0.49 to 0.66 to 0.91, wherein the particle size meets that the particle size of the vanadium oxide is smaller than or equal to 5 mm, the particle size of Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, the particle size of the aluminium powder is smaller than or equal to 5 mm, and the particle size of the slag former is smaller than or equal to 0.2 mm; dividing the materials into 7 batches, wherein the aluminium proportioning amount of each batch of the materials is gradually 1.20, 1.1, 1.0, 0.95, 0.925, 0.90, 0.875 and 0.85 time of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, the total aluminium proportioning amount of the raw materials is 0.94 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, and the weight of the first batch of the materials is 22.2% of that of the total materials; adding the first batch of the materials to a reaction furnace, pouring the first batch of materials into the reaction furnace, performing igniting with magnesium powder from the top of the materials to initiate the self-propagating reaction, and sequentially adding other batches of the materials till complete reaction to obtain high-temperature melt;

(62) (2) Performing heat preserving and smelting on the high-temperature melt through electromagnetic induction heating to realize metal-slag separation to obtain an upper layer alumina-based slag and a lower layer alloy melt, wherein the control parameters are as follows: the electromagnetic induction frequency is greater than or equal to 1000 Hz, the smelting temperature is 1700° C., and the heat preserving time is 5 min;

(63) (3) Removing 90% of upper-layer aluminium oxide based melt slags, jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining, wherein the refining slags consist of the components in mass ratio of 25% of CaF.sub.2 and 75% of CaO, and the control parameters are as follows: the addition amount of the refining slags is 7% of total raw materials, argon gas with purity being greater than or equal to 99.95% is used as carrier gas, the eccentric stirring speed is 150 rpm, the eccentric rate is 0.38, the refining temperature is 1700° C., and the refining time is 30 min; and

(64) (4) Cooling the refined high-temperature melt to room temperature, and removing the upper layer smelting slag to obtain the ferrovanadium alloys.

(65) Furthermore, the prepared ferrovanadium alloys in the embodiment consist of the following chemical components in percentages by mass: 62.4% of V, 0.2% of Si, 0.53% of Al, 0.38% of O, and the balance of Fe.

Embodiment 10

(66) The method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining specially comprises the following steps:

(67) (1) Aluminothermic self-propagating gradient reduction

(68) Preparing the raw materials in mass ratio of the raw materials of V.sub.2O.sub.3, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former CaO being 1.0 to 0.54 to 0.69 to 1.21, wherein the particle size meets that the particle size of the vanadium oxide is smaller than or equal to 5 mm, the particle size of Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, the particle size of the aluminium powder is smaller than or equal to 5 mm, and the particle size of the slag former is smaller than or equal to 0.2 mm; uniformly mixing the raw materials of the V.sub.2O.sub.3, the Fe.sub.2O.sub.3 powder and the slag former to obtain a mixture, adding the mixture into a continuous mixer at an even velocity, adding the aluminium powder into the continuous mixer at a gradiently decreased velocity at the same time, and continuously introducing the uniformly mixed materials into the reaction furnace for the aluminothermic self-propagating reaction, wherein the entire material mixing process and the entire reaction process are performed continuously until all materials react completely to obtain the high-temperature melt, the aluminium proportioning amount of continuous materials introduced into the reaction furnace is gradiently reduced from 1.18 times to 0.69 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, the number a of gradient changes is 0.0035, the number of gradient changes of the aluminium proportioning amount in the entire process is 140 times, and the total aluminium proportioning amount of the raw materials is 0.97 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction;

(69) (2) Performing heat preserving and smelting on the high-temperature melt through electromagnetic induction heating to realize metal-slag separation to obtain an upper layer alumina-based slag and a lower layer alloy melt, wherein the control parameters are as follows: the electromagnetic induction frequency is greater than or equal to 1000 Hz, the smelting temperature is 1750° C., and the heat preserving time is 10 min;

(70) (3) Removing 90% of upper-layer aluminium oxide based melt slags, jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining, wherein the refining slags consist of the components in mass ratio of 10% of CaF.sub.2, 85% of CaO and 5% of Na.sub.2O, and the control parameters are as follows: the addition amount of the refining slags is 5% of total raw materials, argon gas with purity being greater than or equal to 99.95% is used as carrier gas, the eccentric stirring speed is 100 rpm, the eccentric rate is 0.32, the refining temperature is 1750° C., and the refining time is 20 min; and

(71) (4) Cooling the refined high-temperature melt to room temperature, and removing the upper layer smelting slag to obtain the ferrovanadium alloys.

(72) Furthermore, the prepared ferrovanadium alloys in the embodiment consist of the following chemical components in percentages by mass: 60.8% of V, 0.6% of Si, 0.66% of Al, 0.58% of O, and the balance of Fe.

Embodiment 11

(73) The method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining specially comprises the following steps:

(74) (1) Aluminothermic self-propagating gradient reduction

(75) Preparing the raw materials in mass ratio of the raw materials of V.sub.2O.sub.3, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former CaO being 1.0 to 0.61 to 0.71 to 1.34, wherein the particle size meets that the particle size of the vanadium oxide is smaller than or equal to 5 mm, the particle size of Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, the particle size of the aluminium powder is smaller than or equal to 5 mm, and the particle size of the slag former is smaller than or equal to 0.2 mm; uniformly mixing the raw materials of the V.sub.2O.sub.3, the Fe.sub.2O.sub.3 powder and the slag former to obtain a mixture, adding the mixture into a continuous mixer at an even velocity, adding the aluminium powder into the continuous mixer at a gradiently decreased velocity at the same time, and continuously introducing the uniformly mixed materials into the reaction furnace for the aluminothermic self-propagating reaction, wherein the entire material mixing process and the entire reaction process are performed continuously until all materials react completely to obtain the high-temperature melt, the aluminium proportioning amount of continuous materials introduced into the reaction furnace is gradiently reduced from 1.28 times to 0.68 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, the number a of gradient changes is 0.0025, the number of gradient changes of the aluminium proportioning amount in the entire process is 240 times, and the total aluminium proportioning amount of the raw materials is 0.96 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction;

(76) (2) Performing heat preserving and smelting on the high-temperature melt through electromagnetic induction heating to realize metal-slag separation to obtain an upper layer alumina-based slag and a lower layer alloy melt, wherein the control parameters are as follows: the electromagnetic induction frequency is greater than or equal to 1000 Hz, the smelting temperature is 1700° C., and the heat preserving time is 10 min;

(77) (3) Removing 90% of upper-layer aluminium oxide based melt slags, jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining, wherein the refining slags consist of the components in mass ratio of 10% of CaF.sub.2, 80% of CaO and 10% of Na.sub.2O, and the control parameters are as follows: the addition amount of the refining slags is 4% of total raw materials, argon gas with purity being greater than or equal to 99.95% is used as carrier gas, the eccentric stirring speed is 100 rpm, the eccentric rate is 0.35, the refining temperature is 1700° C., and the refining time is 20 min; and

(78) (4) Cooling the refined high-temperature melt to room temperature, and removing the upper layer smelting slag to obtain the ferrovanadium alloys.

(79) Furthermore, the prepared ferrovanadium alloys in the embodiment consist of the following chemical components in percentages by mass: 59.2% of V, 0.7% of Si, 0.56% of Al, 0.44% of O, and the balance of Fe.

Embodiment 12

(80) The method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining specially comprises the following steps:

(81) (1) Aluminothermic self-propagating gradient reduction

(82) Preparing the raw materials in mass ratio of the raw materials of V.sub.2O.sub.3, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former CaO being 1.0 to 0.72 to 0.74 to 1.48, wherein the particle size meets that the particle size of the vanadium oxide is smaller than or equal to 5mm, the particle size of Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, the particle size of the aluminium powder is smaller than or equal to 5 mm, and the particle size of the slag former is smaller than or equal to 0.2 mm; uniformly mixing the raw materials of the V.sub.2O.sub.3, the Fe.sub.2O.sub.3 powder and the slag former to obtain a mixture, adding the mixture into a continuous mixer at an even velocity, adding the aluminium powder into the continuous mixer at a gradiently decreased velocity at the same time, and continuously introducing the uniformly mixed materials into the reaction furnace for the aluminothermic self-propagating reaction, wherein the entire material mixing process and the entire reaction process are performed continuously until all materials react completely to obtain the high-temperature melt, the aluminium proportioning amount of continuous materials introduced into the reaction furnace is gradiently reduced from 1.23 times to 0.75 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, the number a of gradient changes is 0.0015, the number of gradient changes of the aluminium proportioning amount in the entire process is 320 times, and the total aluminium proportioning amount of the raw materials is 0.94 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction;

(83) (2) Performing heat preserving and smelting on the high-temperature melt through electromagnetic induction heating to realize metal-slag separation to obtain an upper layer alumina-based slag and a lower layer alloy melt, wherein the control parameters are as follows: the electromagnetic induction frequency is greater than or equal to 1000 Hz, the smelting temperature is 1700° C., and the heat preserving time is 10 min;

(84) (3) Removing 90% of upper-layer aluminium oxide based melt slags, jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining, wherein the refining slags consist of the components in mass ratio of 20% of CaF.sub.2, 75% of CaO and 5% of Na.sub.2O, and the control parameters are as follows: the addition amount of the refining slags is 8% of total raw materials, argon gas with purity being greater than or equal to 99.95% is used as carrier gas, the eccentric stirring speed is 100 rpm, the eccentric rate is 0.4, the refining temperature is 1700° C., and the refining time is 30 min; and

(85) (4) Cooling the refined high-temperature melt to room temperature, and removing the upper layer smelting slag to obtain the ferrovanadium alloys.

(86) Furthermore, the prepared ferrovanadium alloys in the embodiment consist of the following chemical components in percentages by mass: 56.8% of V, 0.6% of Si, 0.5% of Al, 0.28% of O, and the balance of Fe.

Embodiment 13

(87) The method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining specially comprises the following steps:

(88) (1) Aluminothermic self-propagating gradient reduction

(89) Preparing the raw materials in mass ratio of the raw materials of V.sub.2O.sub.3, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former CaO being 1.0 to 0.2 to 0.56 to 0.85, wherein the particle size meets that the particle size of the vanadium oxide is smaller than or equal to 5 mm, the particle size of Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, the particle size of the aluminium powder is smaller than or equal to 5 mm, and the particle size of the slag former is smaller than or equal to 0.2 mm; dividing the materials into 5 batches, wherein the aluminium proportioning amount of each batch of the materials is gradually 1.20, 1.05, 1.0, 0.90 and 0.85 time of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, the total aluminium proportioning amount of the raw materials is 0.98 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, and the weight of the first batch of the materials is 20% of that of the total materials; adding the first batch of the materials to a reaction furnace, pouring the first batch of materials into the reaction furnace, performing igniting with magnesium powder from the top of the materials to initiate the self-propagating reaction, and sequentially adding other batches of the materials till complete reaction to obtain high-temperature melt;

(90) (2) Performing heat preserving and smelting on the high-temperature melt through electromagnetic induction heating to realize metal-slag separation to obtain an upper layer alumina-based slag and a lower layer alloy melt, wherein the control parameters are as follows: the electromagnetic induction frequency is greater than or equal to 1000 Hz, the smelting temperature is 1800° C., and the heat preserving time is 15 min;

(91) (3) Removing 90% of upper-layer aluminium oxide based melt slags, jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining, wherein the refining slags consist of the components in mass ratio of 10% of CaF.sub.2 and 90% of CaO, and the control parameters are as follows: the addition amount of the refining slags is 2% of total raw materials, argon gas with purity being greater than or equal to 99.95% is used as carrier gas, the eccentric stirring speed is 50 rpm, the eccentric rate is 0.4, the refining temperature is 1800° C., and the refining time is 10 min; and

(92) (4) Cooling the refined high-temperature melt to room temperature, and removing the upper layer smelting slag to obtain the ferrovanadium alloys.

(93) Furthermore, the prepared ferrovanadium alloys in the embodiment consist of the following chemical components in percentages by mass: 79.2% of V, 0.2% of Si, 0.62% of Al, 0.6% of O, and the balance of Fe.

Embodiment 14

(94) The method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining specially comprises the following steps:

(95) (1) Aluminothermic self-propagating gradient reduction

(96) Preparing the raw materials in mass ratio of the raw materials of V.sub.2O.sub.5, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former CaO being 1.0 to 0.26 to 0.57 to 0.88, wherein the particle size meets that the particle size of the vanadium oxide is smaller than or equal to 5 mm, the particle size of Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, the particle size of the aluminium powder is smaller than or equal to 5 mm, and the particle size of the slag former is smaller than or equal to 0.2 mm; dividing the materials into 6 batches, wherein the aluminium proportioning amount of each batch of the materials is gradually 1.20, 1.1, 0.95, 0.90, 0.85 and 0.80 time of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, the total aluminium proportioning amount of the raw materials is 0.95 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, and the weight of the first batch of the materials is 28.6% of that of the total materials; adding the first batch of the materials to a reaction furnace, pouring the first batch of materials into the reaction furnace, performing igniting with magnesium powder from the top of the materials to initiate the self-propagating reaction, and sequentially adding other batches of the materials till complete reaction to obtain high-temperature melt;

(97) (2) Performing heat preserving and smelting on the high-temperature melt through electromagnetic induction heating to realize metal-slag separation to obtain an upper layer alumina-based slag and a lower layer alloy melt, wherein the control parameters are as follows: the electromagnetic induction frequency is greater than or equal to 1000 Hz, the smelting temperature is 1750° C., and the heat preserving time is 10 min;

(98) (3) Removing 90% of upper-layer aluminium oxide based melt slags, jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining, wherein the refining slags consist of the components in mass ratio of 20% of CaF.sub.2 and 80% of CaO, and the control parameters are as follows: the addition amount of the refining slags is 5% of total raw materials, argon gas with purity being greater than or equal to 99.95% is used as carrier gas, the eccentric stirring speed is 100 rpm, the eccentric rate is 0.4, the refining temperature is 1750° C., and the refining time is 20 min; and

(99) (4) Cooling the refined high-temperature melt to room temperature, and removing the upper layer smelting slag to obtain the ferrovanadium alloys.

(100) Furthermore, the prepared ferrovanadium alloys in the embodiment consist of the following chemical components in percentages by mass: 78.5% of V, 0.3% of Si, 0.58% of Al, 0.58% of O, and the balance of Fe.

Embodiment 15

(101) The method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining specially comprises the following steps:

(102) (1) Aluminothermic self-propagating gradient reduction

(103) Preparing the raw materials in mass ratio of the raw materials of V.sub.2O.sub.5, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former CaO being 1.0 to 0.27 to 0.58 to 0.96, wherein the particle size meets that the particle size of the vanadium oxide is smaller than or equal to 5 mm, the particle size of Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, the particle size of the aluminium powder is smaller than or equal to 5 mm, and the particle size of the slag former is smaller than or equal to 0.2 mm; dividing the materials into 7 batches, wherein the aluminium proportioning amount of each batch of the materials is gradually 1.20, 1.1, 1.0, 0.95, 0.925, 0.90 and 0.85 time of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, the total aluminium proportioning amount of the raw materials is 0.94 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, and the weight of the first batch of the materials is 22.2% of that of the total materials; adding the first batch of the materials to a reaction furnace, pouring the first batch of materials into the reaction furnace, performing igniting with magnesium powder from the top of the materials to initiate the self-propagating reaction, and sequentially adding other batches of the materials till complete reaction to obtain high-temperature melt;

(104) (2) Performing heat preserving and smelting on the high-temperature melt through electromagnetic induction heating to realize metal-slag separation to obtain an upper layer alumina-based slag and a lower layer alloy melt, wherein the control parameters are as follows: the electromagnetic induction frequency is greater than or equal to 1000 Hz, the smelting temperature is 1700° C., and the heat preserving time is 5 min;

(105) (3) Removing 90% of upper-layer aluminium oxide based melt slags, jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining, wherein the refining slags consist of the components in mass ratio of 25% of CaF.sub.2 and 75% of CaO, and the control parameters are as follows: the addition amount of the refining slags is 7% of total raw materials, argon gas with purity being greater than or equal to 99.95% is used as carrier gas, the eccentric stirring speed is 150 rpm, the eccentric rate is 0.34, the refining temperature is 1700° C., and the refining time is 30 min; and

(106) (4) Cooling the refined high-temperature melt to room temperature, and removing the upper layer smelting slag to obtain the ferrovanadium alloys.

(107) Furthermore, the prepared ferrovanadium alloys in the embodiment consist of the following chemical components in percentages by mass: 76.5% of V, 0.2% of Si, 0.49% of Al, 0.26% of O, and the balance of Fe.

Embodiment 16

(108) The method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining specially comprises the following steps:

(109) (1) Aluminothermic self-propagating gradient reduction

(110) Preparing the raw materials in mass ratio of the raw materials of V.sub.2O.sub.5, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former CaO being 1.0 to 0.29 to 0.59 to 1.06, wherein the particle size meets that the particle size of the vanadium oxide is smaller than or equal to 5 mm, the particle size of Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, the particle size of the aluminium powder is smaller than or equal to 5 mm, and the particle size of the slag former is smaller than or equal to 0.2 mm; uniformly mixing the raw materials of the V.sub.2O.sub.5, the Fe.sub.2O.sub.3 powder and the slag former to obtain a mixture, adding the mixture into a continuous mixer at an even velocity, adding the aluminium powder into the continuous mixer at a gradiently decreased velocity at the same time, and continuously introducing the uniformly mixed materials into the reaction furnace for the aluminothermic self-propagating reaction, wherein the entire material mixing process and the entire reaction process are performed continuously until all materials react completely to obtain the high-temperature melt, the aluminium proportioning amount of continuous materials introduced into the reaction furnace is gradiently reduced from 1.29 times to 0.69 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, the number a of gradient changes is 0.003, the number of gradient changes of the aluminium proportioning amount in the entire process is 200 times, and the total aluminium proportioning amount of the raw materials is 0.97 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction;

(111) (2) Performing heat preserving and smelting on the high-temperature melt through electromagnetic induction heating to realize metal-slag separation to obtain an upper layer alumina-based slag and a lower layer alloy melt, wherein the control parameters are as follows: the electromagnetic induction frequency is greater than or equal to 1000 Hz, the smelting temperature is 1750° C., and the heat preserving time is 10 min;

(112) (3) Removing 90% of upper-layer aluminium oxide based melt slags, jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining, wherein the refining slags consist of the components in mass ratio of 10% of CaF.sub.2, 85% of CaO and 5% of Na.sub.2O, and the control parameters are as follows: the addition amount of the refining slags is 5% of total raw materials, argon gas with purity being greater than or equal to 99.95% is used as carrier gas, the eccentric stirring speed is 100 rpm, the eccentric rate is 0.2, the refining temperature is 1750° C., and the refining time is 20 min; and

(113) (4) Cooling the refined high-temperature melt to room temperature, and removing the upper layer smelting slag to obtain the ferrovanadium alloys.

(114) Furthermore, the prepared ferrovanadium alloys in the embodiment consist of the following chemical components in percentages by mass: 75.8% of V, 0.6% of Si, 0.58% of Al, 0.58% of O, and the balance of Fe.

Embodiment 17

(115) The method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining specially comprises the following steps:

(116) (1) Aluminothermic self-propagating gradient reduction

(117) Preparing the raw materials in mass ratio of the raw materials of V.sub.2O.sub.5, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former CaO being 1.0 to 0.3 to 0.6 to 1.2, wherein the particle size meets that the particle size of the vanadium oxide is smaller than or equal to 5 mm, the particle size of Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, the particle size of the aluminium powder is smaller than or equal to 5 mm, and the particle size of the slag former is smaller than or equal to 0.2 mm; uniformly mixing the raw materials of the V.sub.2O.sub.5, the Fe.sub.2O.sub.3 powder and the slag former to obtain a mixture, adding the mixture into a continuous mixer at an even velocity, adding the aluminium powder into the continuous mixer at a gradiently decreased velocity at the same time, and continuously introducing the uniformly mixed materials into the reaction furnace for the aluminothermic self-propagating reaction, wherein the entire material mixing process and the entire reaction process are performed continuously until all materials react completely to obtain the high-temperature melt, the aluminium proportioning amount of continuous materials introduced into the reaction furnace is gradiently reduced from 1.21 times to 0.74 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, the number a of gradient changes is 0.002, the number of gradient changes of the aluminium proportioning amount in the entire process is 235 times, and the total aluminium proportioning amount of the raw materials is 0.95 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction;

(118) (2) Performing heat preserving and smelting on the high-temperature melt through electromagnetic induction heating to realize metal-slag separation to obtain an upper layer alumina-based slag and a lower layer alloy melt, wherein the control parameters are as follows: the electromagnetic induction frequency is greater than or equal to 1000 Hz, the smelting temperature is 1700° C., and the heat preserving time is 10 min;

(119) (3) Removing 90% of upper-layer aluminium oxide based melt slags, jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining, wherein the refining slags consist of the components in mass ratio of 10% of CaF.sub.2, 80% of CaO and 10% of Na.sub.2O, and the control parameters are as follows: the addition amount of the refining slags is 4% of total raw materials, argon gas with purity being greater than or equal to 99.95% is used as carrier gas, the eccentric stirring speed is 100 rpm, the eccentric rate is 0.3, the refining temperature is 1700° C., and the refining time is 20 min; and

(120) (4) Cooling the refined high-temperature melt to room temperature, and removing the upper layer smelting slag to obtain the ferrovanadium alloys.

(121) Furthermore, the prepared ferrovanadium alloys in the embodiment consist of the following chemical components in percentages by mass: 74.3% of V, 0.7% of Si, 0.47% of Al, 0.52% of O, and the balance of Fe.

Embodiment 18

(122) The method for preparing ferrovanadium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining specially comprises the following steps:

(123) (1) Aluminothermic self-propagating gradient reduction

(124) Preparing the raw materials in mass ratio of the raw materials of V.sub.2O.sub.5, Fe.sub.2O.sub.3 powder, aluminium powder and a slag former CaO being 1.0 to 0.32 to 0.6 to 1.22, wherein the particle size meets that the particle size of the vanadium oxide is smaller than or equal to 5 mm, the particle size of Fe.sub.2O.sub.3 is smaller than or equal to 0.2 mm, the particle size of the aluminium powder is smaller than or equal to 5 mm, and the particle size of the slag former is smaller than or equal to 0.2 mm; uniformly mixing the raw materials of the V.sub.2O.sub.5, the Fe.sub.2O.sub.3 powder and the slag former to obtain a mixture, adding the mixture into a continuous mixer at an even velocity, adding the aluminium powder into the continuous mixer at a gradiently decreased velocity at the same time, and continuously introducing the uniformly mixed materials into the reaction furnace for the aluminothermic self-propagating reaction, wherein the entire material mixing process and the entire reaction process are performed continuously until all materials react completely to obtain the high-temperature melt, the aluminium proportioning amount of continuous materials introduced into the reaction furnace is gradiently reduced from 1.16 times to 0.78 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction, the number a of gradient changes is 0.001, the number of gradient changes of the aluminium proportioning amount in the entire process is 380 times, and the total aluminium proportioning amount of the raw materials is 0.94 times of the theoretical stoichiometric ratio of the aluminothermic self-propagating reaction;

(125) (2) Performing heat preserving and smelting on the high-temperature melt through electromagnetic induction heating to realize metal-slag separation to obtain an upper layer alumina-based slag and a lower layer alloy melt, wherein the control parameters are as follows: the electromagnetic induction frequency is greater than or equal to 1000 Hz, the smelting temperature is 1700° C., and the heat preserving time is 15 min;

(126) (3) Removing 90% of upper-layer aluminium oxide based melt slags, jetting refining slags into the lower layer alloy melt, and performing stirring and slag washing refining, wherein the refining slags consist of the components in mass ratio of 20% of CaF.sub.2, 75% of CaO and 5% of Na.sub.2O, and the control parameters are as follows: the addition amount of the refining slags is 8% of total raw materials, argon gas with purity being greater than or equal to 99.95% is used as carrier gas, the eccentric stirring speed is 100 rpm, the eccentric rate is 0.31, the refining temperature is 1700° C., and the refining time is 30 min; and

(127) (4) Cooling the refined high-temperature melt to room temperature, and removing the upper layer smelting slag to obtain the ferrovanadium alloys.

(128) Furthermore, the prepared ferrovanadium alloys in the embodiment consist of the following chemical components in percentages by mass: 71.4% of V, 0.6% of Si, 0.42% of Al, 0.25% of O, and the balance of Fe.

(129) It should be understood that improvements or transformations can be made based on the above description by ordinary technicians in the art, and all of these improvements and transformations shall fall within the scope of protection claimed in the present invention.