METHOD FOR PRODUCING MAGNESIUM-LITHIUM ALLOY BY GASEOUS CO-CONDENSATION METHOD

Abstract

The present invention belongs to the technical field of preparation of light metal alloy materials, in particular to a method for producing a magnesium-lithium alloy by a gaseous co-condensation method. The method comprises the steps of: 1) mixing and briquetting a lithium salt, a refractory agent and a catalyst under pressure, and then thermally decomposing to form an unsaturated composite oxide; 2) respectively crushing and ball-milling, and then briquetting the unsaturated composite oxide, magnesium oxide, a reducing agent and a fluxing agent; 3) reducing briquettes in vacuum; 4) making a gas pass through a first condensing chamber of a temperature control device, and then purifying; 5) The purified metal gas is condensed into the condensing phase of the alloy through the second condensing chamber of a quenching device; 6) obtaining the magnesium-lithium alloy with a purity being 99.5% or above by virtue of smelting and flux-refining, and then purifying by distillation. The magnesium-lithium alloy obtained in the present application is not segregated, so that a stable β-phase solid solution or a compound having an increasing purity being 99.95% is formed.

Claims

1. A method for producing a magnesium-lithium alloy by a gaseous co-condensation method, comprising the following steps: 1) The lithium salt, the refractory agent and catalyst are mixed in proportion and briqueted under pressure, wherein a briquetted mixture is charged into an industrial tube furnace for thermal decomposition, an unsaturated composite oxide is generated by lithium oxide and the refractory agent, and the sublimated and condensed catalyst is recycled; 2) respectively crushing and ball-milling the unsaturated composite oxide generated in step 1), magnesium oxide, the reducing agent and a fluxing agent, and then briquetting; 3) charging briquettes in step 2) into an industrial heat-resistant tube furnace for vacuum reduction, at this time, the reduction product is in the gaseous state and carries solid materials; 4) making a gas carrying the solid materials in step 3) pass through a centrifugal filter in the dust chamber of a temperature control device, and then entering the first condensing chamber, and controlling the temperatures of a centrifugal separator and the first condensing chamber to be 850-950° C. with the gas at the airflow velocity of 1.2-1.8 m/sec; removing the vast majority of solid particles; and then making the gas pass through the micron ceramic filter to purify more than 99.95% of solid particles with dust, and controlling an outlet temperature to be 700-750° C.; 5) After purification the pure metal gas passes through the second condensing chamber of the quenching device, using the cooling liquid at below −100° C. to thermally exchange with a metal gas on an outer layer of a condenser in the second condensing chamber, and transferring heat to an inner wall by a gas in a center of a cooler to rapidly condense the metal gas as a condensed phase of the alloy; 6) obtaining the magnesium-lithium alloy having a purity being 99.5% or above by virtue of flux smelting and refining of the magnesium-lithium alloy in the condensed phase in a pit furnace under the protection of Ar; 7) separating the magnesium-lithium alloy raw ingot by distillation to obtain the magnesium-lithium alloy having a purity being 99.95% or above.

2. The method according to claim 1, wherein the lithium salt is lithium-containing carbonate, nitrate, sulfate, silicate or lithium-containing sulfide, the refractory agent is CaO, Al.sub.2O.sub.3 or MgO, and the catalyst is Sb.sub.2O.sub.3 or Bi.sub.2O.sub.3; and a molar ratio of the lithium salt to the refractory agent to the catalyst is 1:1.4-1.8:0.2-0.8.

3. The method according to claim 1, wherein a granularity of each of the lithium salt, the refractory agent and the catalyst in step 1) is less than 100 μm; each briquette is required to be of an almond shape at a weight of 25-35 g/Nr.; the pressure briquetting condition is 35-45 Mpa, and the thermal decomposition temperature is 860-900° C.

4. The method according to claim 1, wherein the unsaturated composite oxide, the magnesium oxide, the reducing agent and the fluxing agent in step 2) are respectively crushed and ball-milled, and then briquetted, and the granularity thereof is 40-100 μm after ball-milling; the briquetting conditions include: briquetting into an almond shape at a weight of 25-35 g/Nr. at 30-45 Mpa.

5. The method according to claim 1, wherein the reducing agent is high silicon iron, aluminium powder having an Al content being more than or equal to 99 wt %, aluminium powder having an activity being 70 wt % and the granularity being less than 8 μm, the aluminum silicon powder having an Al—Si content being more than or equal to 98% or carbon powder ; the fluxing agent is CaF.sub.2, with a purity thereof of 97.5%; the mass ratio of the unsaturated composite oxide to the magnesium oxide is 3-80:20-97; the mass ratio of the total mass of the unsaturated composite oxide and the magnesium oxide to the reducing agent to the fluxing agent is 76-87:15-23:1-3.

6. The method according to claim 1, wherein for the industrial tube furnace for thermal decomposition, the vacuum degree is 10-20 pa, the temperature is 860-950° C., the size is φ159-φ330 mm*3,300 mm, and the thermal decomposition rate is more than or equal to ≥99%.

7. The method according to claim 1, wherein for an industrial heat-resistant tube furnace for thermal reduction, a size is 159-φ 330 mm*3,300 mm, the vacuum degree is 1-20 pa, the temperature is 900-1,300° C., and the thermal reduction rate is more than or equal to 99%.

8. The method according to claim 1, wherein the quenching temperature control device comprises a reaction zone (1), a dust chamber (2), the first condensing chamber (3), the second condensing chamber (4), a slag discharge hole (5) of the dust chamber and a vacuum tube (6); the reaction zone (1) is in communication with the dust chamber (2); the centrifugal separator is arranged in the dust chamber (2), a lower end of which is provided with a funnel; a lower end of one side of the funnel is provided with a heating zone inlet (7), and the slag discharge hole (5) of the dust chamber is defined at the bottom of the funnel; an upper end of one side of the dust chamber (2) is provided with a first heating zone outlet (8), the top of the dust chamber (2) is provided with the first condensing chamber (3), a second heating zone outlet (10) is defined at an upper end of a connection between the first condensing chamber (3) and the dust chamber (2) and a ceramic micron filter (15) is arranged in the first condensing chamber (3); the first condensing chamber (3) is in communication with the second condensing chamber (4); a second heating zone inlet (9) is defined in a connection with the second condensing chamber (4) in the first condensing chamber (3); the vacuum tube (6) is arranged on a connection with the first condensing chamber (3) within the second condensing chamber (4), and a cooling liquid inlet (12) and a cooling air inlet (13) as well as a cooling liquid outlet (11) and a cooling air outlet (14) are respectively defined at both sides of the second condensing chamber (4).

9. The method according to claim 8, wherein the first condensing chamber (3) and the second condensing chamber (4) are double-casing coolers; in the second condensing chamber (4), a gas velocity in the center of the cooler is 1.5-4 m/sec, and the ratio of the cooling area to the metal of the condensate phase is 0.4-0.7 dm.sup.3/kg.

10. The method according to claim 8, wherein in a refining step, the lower temperature of the distillation column is controlled to be 850-950° C., the middle temperature to be 700-800° C. and the upper temperature to be lower than 100° C., and then distillation separation is carried out; and the middle liquid, which is 99.95% magnesium-lithium alloy, is subject to ingot casting to obtain a magnesium-lithium alloy finished product.

Description

DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a process flow diagram of a method for producing a magnesium-lithium alloy by a gaseous co-condensation method provided by the present invention.

[0023] FIG. 2 is a structural diagram of the quenching device provided by the present invention.

[0024] In which, 1—reaction zone, 2—dust chamber, 3—first condensing chamber, 4—second condensing chamber, 5—slag discharge hole of dust chamber, 6—vacuum tube, 7—first heating zone inlet, 8—first heating zone outlet, 9—second heating zone inlet, 10—second heating zone outlet, 11—cooling liquid outlet, 12—cooling liquid inlet, 13—cooling air inlet, 14—cooling air outlet, and 15—ceramic micron filter.

DESCRIPTION OF EMBODIMENTS

[0025] The present invention will be further described in detail in combination with specific implementations for the purpose of clear understanding of the objectives, technical solutions and advantages of the present invention, but it shall not be understood that the scope of the above subject of the present invention is only limited to the following embodiments.

[0026] The structure of the quenching device used in the following embodiments are as follows: the quenching temperature control device comprises a reaction zone, a dust chamber, a first condensing chamber, a second condensing chamber, and a slag discharge hole of the dust chamber and a vacuum tube, and the reaction zone thereof is in communication with the duct chamber; a centrifugal separator is arranged in the dust chamber, a lower end of which is provided with a funnel; a lower end of one side of the funnel is provided with a first heating zone inlet, and the slag discharge hole of the dust chamber is defined at the bottom of the funnel; the upper end of one side of the dust chamber is provided with the first heating zone outlet, the top of the dust chamber is provided with the first condensing chamber, the second heating zone outlet is defined at the upper end of the connection between the first condensing chamber and the dust chamber and a ceramic micron filter is arranged in the first condensing chamber; the first condensing chamber is in communication with the second condensing chamber; the second heating zone inlet is defined in the connection with the second condensing chamber in the first condensing chamber; the vacuum tube is arranged on the connection with the first condensing chamber in the second condensing chamber, and the cooling liquid inlet and the cooling air inlet as well as the cooling liquid outlet and the cooling air outlet are respectively defined at both sides of the second condensing chamber.

[0027] The first and second condensing chambers are double-casing coolers.

[0028] A technology of separation by distillation is prior art.

Embodiment 1

[0029] A method for producing a magnesium-lithium alloy by the gaseous co-condensation method, comprising the following steps:
1) Raw materials are weighed in proportion, wherein the granularity of lithium carbonate is 89 μm, and the granularity of calcium oxide is 74 μm; the lithium carbonate, CaO and a catalyst Sb.sub.2O.sub.3 are mixed in a molar ratio of 1:1.6:0.4, and briquetted under the pressure of 35 Mpa; each briquette is 28 g, and is of an almond shape. The prepared briquettes are charged into a φ330 mm*3,300 mm industrial tube furnace with a vapor-deposited nitrocarbon compound crucible for thermal decomposition, the sublimated and condensed catalyst is recycled, and an unsaturated composite oxide is generated by lithium oxide and a refractory agent. The vacuum degree of the industrial tube furnace is 10 pa, and the temperature is 860° C. High temperature decomposition time is 5 h, the decomposition rate of the lithium carbonate decomposed into lithium oxide is 99.2%, and a metal lithium yield reaches 99.5%.
2) The mass ratio of the unsaturated composite oxide formed by the lithium oxide obtained in step 1) and the refractory agent to the magnesium oxide is 88.2:11.8 (in the composite oxide, MgO:CaO=1:1); the unsaturated composite oxide, the magnesium oxide, silicon iron and CaF.sub.2 are respectively crushed and ball-milled till a granularity is 60 and then mixed according to a mass ratio of the total mass of the unsaturated composite oxide and the magnesium oxide to the silicon iron to the CaF.sub.2 of 80:18:2, and finally pressed into briquettes at the weight of 28 g/Nr. under the pressure of 30 Mpa.
3) The briquettes in step 2) are put into a φ330 mm*3,300 mm industrial heat-resistant tube furnace having the vacuum degree being 1 pa and the temperature being 1,185° C.; and at this time, the reduction product is in the gaseous state and carries solid materials, the magnesium reduction recovery is more than 95% and a lithium reduction is 99%.
4) The gas carrying the solid materials passes through a centrifugal filter in the dust chamber and the first condensing chamber, wherein the first condensing chamber has a sandwich; and the temperatures of a centrifugal separator and the first condensing chamber are controlled to be 880° C. with the gas at an airflow velocity of 1.5 m/sec; and the gas carrying 98% of more than 20 μm solid particles is removed while passing through the first condensing chamber, more than 99.95% of carried dust is purified when the gas passes through 0.5 μm micron ceramic filter, and an outlet temperature is controlled to be 730° C.
5) The pure metal gas passes through the second condensing chamber of the quenching device; when the temperature of an inner layer of a double-casing cooler of the second condensing chamber is controlled to be 60° C., the low temperature cooling liquid below −110° C. is thermally exchanged with the metal gas on an outer layer; heat is transferred to an inner wall from a center of the cooler by the gas at 3 m/sec, and the cooling area is 0.65 dm.sup.3/kg, so that the metal gas may be condensed as the condensed phase of the alloy.
6) A magnesium-lithium alloy raw ingot having a purity being 99.5% is obtained by flux smelting and refining of the magnesium-lithium alloy in the condensed phase in the pit furnace under the protection of Ar and mixing.
7) The magnesium-lithium alloy raw ingot is separated by distillation; the lower temperature of the distiller is controlled to be 900° C., the middle temperature to be 750° C., and the upper temperature to be 70° C.; impurities with the high melting point are removed from the lower part, including Fe, Ni, Co, Si and Ca; metal impurities with the low melting point are removed from the upper part, including k, Na, and a magnesium-lithium alloy is discharged from a middle part.

[0030] Finally, the magnesium-lithium alloy is subject to ingot casting, and then stored after surface treatment.

[0031] The obtained magnesium-lithium alloy is detected according to the national standards, and the mass percentages of all elements are as follows:

TABLE-US-00001 Mg Li Fe Ni Cu Al Mn 90.752 9.2 0.0015 0.00045 0.00035 0.004 0.0005 Ti Ca Si Zn K Na Others 0.0003 0.015 0..0055 0.0008 0.0046 0.009 0.006
As can be seen from the above, the purity of the magnesium-lithium alloy obtained by the method reaches 99.95 wt %, the stable and uniform α- and β-phase solid solutions and compounds of the magnesium-lithium alloy are formed, and a good processibility can be realized, so that the alloy can meet the applications in various industrial fields. Compared with the direct mixing, the manufacture cost is as low as 20-30%, the raw material sources are abundant, the segregation phenomenon is overcome, the purity is improved, the alloy property is improved, and industrialization is realized.

Embodiment 2

[0032] A method for producing a magnesium-lithium alloy by the gaseous co-condensation method, comprising the following steps:

1) Raw materials are weighed in proportion, wherein the granularity of lithium carbonate is 89 and the granularity of calcium oxide is 74 μm; the lithium carbonate, CaO+MgO, Al.sub.2O.sub.3 and a catalyst Sb.sub.2O.sub.3 are mixed in a molar ratio of 1:1.45:0.2:0.4, and then briquetted under the pressure of 40 Mpa; each briquette is 28 g, and is of an almond shape. The prepared briquettes are charged into a vapor-deposited nitrocarbon compound crucible of a φ330 mm*3,300 mm industrial tube furnace for thermal decomposition, the sublimated and condensed catalyst is recycled, and the unsaturated composite oxide is generated by lithium oxide and a refractory agent. the vacuum degree of the industrial tube furnace is 10 pa, and the temperature is 860° C. High temperature decomposition time is 5 h, the decomposition rate of the lithium carbonate decomposed into lithium oxide is 99.3%, and a metal lithium yield reaches 99.5%.
2) The mass ratio of the unsaturated composite oxide formed by the lithium oxide obtained in step 1) and the refractory agent to the magnesium oxide is 87.7:12.3; the unsaturated composite oxide, the magnesium oxide, silicon iron and CaF.sub.2 are respectively crushed and ball-milled till a granularity is 60 μm, and then mixed according to a mass ratio of the total mass of the unsaturated composite oxide and the magnesium oxide to the silicon iron to the CaF.sub.2 of 79:19:2, and finally pressed into briquettes at the weight of 28 g/Nr. under the pressure of 30 Mpa.
3) The briquettes in step 2) are put into a φ330 mm*3,300 mm industrial heat-resistant tube furnace, wherein the vacuum degree is controlled to be 3 pa and the temperature to be 1,200° C.; and at this time, the reduction product is in the gaseous state and carries solid materials, the magnesium reduction recovery is more than 95.1%, and a lithium reduction is 99.1%.
4) The gas carrying the solid materials passes through a centrifugal filter in the dust chamber and a first condensing chamber, wherein the first condensing chamber has a sandwich; and the temperatures of a centrifugal separator and the first condensing chamber are controlled to be 900° C. with the constant-temperature gas at an airflow velocity of 1.6 m/sec; the gas carrying 98% of more than 20 μm solid particles is removed while passing through the first condensing chamber, more than 99.95% of carried dust is purified when the gas passes through 0.5 μm micron ceramic filter, and an outlet temperature is controlled to be 740° C.
5) The pure metal gas passes through a quenching second condensing chamber; for the condenser that is the double-casing cooler, when the temperature of the inner layer is controlled to be 65° C., the low temperature cooling liquid below −105° C. is thermally exchanged with the metal gas on an outer layer; heat is transferred to the inner wall from the center of the cooler by a gas at 4 m/sec, and the cooling area is 0.7 dm.sup.3/kg, so that the metal gas may be rapidly condensed as the condensed phase of the alloy.
6) A magnesium-lithium alloy raw ingot having a purity being 99.5% is obtained by flux smelting and refining of the magnesium-lithium alloy in the condensed phase in the pit furnace under the protection of Ar.
7) A magnesium-lithium alloy raw ingot is separated by distillation. The lower temperature of the distiller is controlled to be 930° C., the middle temperature to be 780° C., and the upper temperature to be 70° C.; impurities with the high melting point are removed from the lower part, including Fe, Ni, Co, Si and Ca; metal impurities with a low melting point are removed from an upper part, including k, Na, and a magnesium-lithium alloy is discharged from a middle part.

[0033] The obtained magnesium-lithium alloy is detected according to the national standards, and the mass percentages of all elements are as follows:

TABLE-US-00002 Mg Li Fe Ni Cu Al Mn 90.151 9.8 0.0013 0.00032 0.00038 0.006 0.0005 Ti Ca Si Zn K Na Others 0.0003 0.016 0.0038 0.0007 0.0047 0.008 0.007

Embodiment 3

[0034] A method for producing a magnesium-lithium alloy by the gaseous co-condensation method, comprising the following steps:

1) An industrial grade lithium nitrate is roasted at the temperature of 680° C. for 7 h to form stable Li.sub.2O.1.75 CaO without briquetting, wherein the decomposition rate of lithium nitrate decomposed into lithium oxide is 98.1%, and a yield of metal lithium reaches 90.1%.
2) The mass ratio of the unsaturated composite oxide formed by the lithium oxide obtained in step 1) to MgO is 79.5:20.5; the unsaturated composite oxide, the MgO, silicon iron and CaF.sub.2 are respectively crushed till the granularity is 60 μm, and then mixed according to the mass ratio of the total mass of the unsaturated composite oxide and the MgO to the silicon iron to the CaF.sub.2 of 80:18:2, and finally pressed into almond briquettes at the weight of 30 g/Nr. under the pressure of 35 Mpa.
3) The briquettes in step 2) are put into a φ330 mm*3,300 mm industrial heat-resistant tube furnace with the vacuum degree of 3 pa and the temperature of 1,200° C.; and at this time, the reduction product is in the gaseous state and carries solid materials, the magnesium reduction recovery is more than 88.6%, and the lithium reduction is 89.3%.
4) the gas carrying solid particles passes through the gas at the air flow velocity of 1.4/sec, the centrifugal separation dedusting temperature with the jacket is controlled to be 910° C., the gas carrying 98% of more than 20 μm solid particles is removed while passing through the first condensing chamber, more than 99.95% of carried dust is purified when the gas passes through 0.5 μm micron ceramic filter, and the gas temperature at the outlet is controlled to be 720° C.
5) The pure metal gas passes through the quenched second condensing chamber; for the condenser that is a double-casing cooler, when the internal temperature is controlled to be 60° C., the low temperature cooling liquid below −110° C. is thermally exchanged with the metal gas on the outer layer; heat is transferred to the inner wall from the center of the cooler by the gas at 4 m/sec, and the cooling area is 0.55 dm.sup.3/kg, so that the metal gas may be rapidly condensed as the condensed phase of the alloy.
6) A magnesium-lithium alloy raw ingot having a purity being 99.5% is obtained by flux smelting and refining of the magnesium-lithium alloy in the condensed phase in the pit furnace under the protection of Ar.
7) A magnesium-lithium alloy raw ingot is separated by distillation, the lower temperature is controlled to be 880° C., the middle temperature to be 730° C., and the upper temperature to be lower than 80° C.; impurities with the high melting point are removed from the lower part, including Fe, Ni, Co, Si and Ca, metal impurities with the high melting point are removed from the upper part, including k, Na, and the magnesium-lithium alloy is discharged from a middle part.
The obtained magnesium-lithium alloy is detected according to the national standards, and the mass percentages of all elements are as follows:

TABLE-US-00003 Mg Li Fe Ni Cu Al Mn 89.651 10.3 0.0015 0.00045 0.00035 0.003 0.0008 Ti Ca Si Zn K Na Others 0.0003 0.018 0.0067 0.0008 0.0031 0.009 0.005

[0035] With a rather long decomposition time during the thermal decomposition, the direct thermal decomposition of lithium nitrate will cause low lithium yield and high energy consumption ratio during the thermal decomposition; the unsaturated composite oxide formed by decomposition into the lithium oxide, MgO, silicon iron and CaF.sub.2 are crushed and mixed difficultly, and mixed nonuniformly; the proportions thereof in the almond briquettes are not uniform, and the reduction is lowered. Compared with the lithium carbonate, links are complicated in the whole process, and the yield is lower than that of the lithium carbonate, thereby increasing the manufacturing cost.

Embodiment 4

[0036] 1) An industrial grade lithium sulfate is roasted at the temperature of 920° C. for 8 h to form stable Li.sub.2O.1.85 CaO (MgO) without briquetting, wherein the decomposition rate of lithium sulfate decomposed into lithium oxide is 95.1%, and a yield of metal lithium reaches 96.1%.
2) The mass ratio of the unsaturated composite oxide formed by the lithium oxide obtained in step 1) to MgO is 80.2:19.8; the unsaturated composite oxide, the MgO, silicon iron and CaF.sub.2 are respectively crushed till the granularity is 60 and then mixed according to the mass ratio of the total mass of the unsaturated composite oxide and the MgO to the silicon iron to the CaF.sub.2 of 80:18:2, and finally pressed into almond briquettes at the weight of 30 g/Nr. under the pressure of 35 Mpa.
3) The briquettes in step 1) are respectively charged into a φ330 mm*3,300 mm industrial heat-resistant tube furnace with the vacuum degree of 3 pa and the temperature of 1,220° C.; and at this time, the reduction product is in a gaseous state and carries solid materials, the magnesium reduction recovery is more than 90.2%, and a lithium reduction is 88.2%.
4) The gas carrying solid particles passes through the gas at the air flow velocity of 1.45/sec, the centrifugal separation dedusting temperature with the jacket is controlled to be 920° C., the gas carrying 98% of more than 20 μm solid particles is removed while passing through the first condensing chamber, more than 99.95% of carried dust is purified when the gas passes through 0.5 μm micron ceramic filter, and the gas temperature at an outlet is controlled to be 740° C.
5) The pure metal gas passes through the quenched second condensing chamber; for the condenser that is a double-casing cooler, when the internal temperature is controlled to be 65° C., the low temperature cooling liquid below −110° C. is thermally exchanged with the metal gas on the outer layer; heat is transferred to the inner wall from the center of the cooler by the gas at 2.8 m/sec, and the cooling area is 0.6 dm.sup.3/kg, so that the metal gas may be rapidly condensed as the condensed phase of the alloy.
6) A magnesium-lithium alloy raw ingot having a purity being 99.5% is obtained by flux smelting and refining of the magnesium-lithium alloy in the condensed phase in the pit furnace under the protection of Ar.
7) A magnesium-lithium alloy raw ingot is separated by distillation, the lower temperature is controlled to be 870° C., the middle temperature to be 720° C., and the upper temperature to be 70° C.; impurities with the high melting point are removed from the lower part, including Fe, Ni, Co, Si and Ca, metal impurities with the high melting point are removed from the upper part, including k, Na, and the magnesium-lithium alloy is discharged from a middle part.
The obtained magnesium-lithium alloy is detected according to the national standards, and the mass percentages of all elements are as follows:

TABLE-US-00004 Mg Li Fe Ni Cu Al Mn 91.05 8.9 0.0016 0.0002 0.0005 0.0041 0.0006 Ti Ca Si Zn K Na Others 0.0004 0.016 0.0059 0.0009 0.0048 0.009 0.006

[0037] Through repeated verification, the impurity contents in the magnesium-lithium alloy are better than those specified in Standards GB/T5153-2016 and GB/T33141-2016.

[0038] Lithium sulfate is decomposed more difficultly compared with lithium carbonate and cannot be decomposed completely. Hence, the direct thermal decomposition will cause low lithium yield, high energy consumption ratio, and long thermal decomposition time; the unsaturated composite oxide formed by decomposition into the lithium oxide, MgO, silicon iron and CaF2 are crushed and mixed difficultly, and mixed nonuniformly; the proportions thereof in the almond briquettes are not uniform, and the reduction is lowered. Compared with the lithium carbonate, intermediate links of the whole process are complicated, and the yield is lower than that of the lithium carbonate, and the manufacturing cost is increased.

Experiment 1:

[0039] Raw materials and method steps in Embodiment 1 are used for experiment, which only changes the temperatures of first and second condensing chambers in the temperature control device, and other conditions are the same as Embodiment 1. Specific test conditions and results are as follows:

TABLE-US-00005 Outlet of First first Second condensing condensing condensing chamber chamber chamber Test (degree) (degree) (degree) Configuration result 980 800 90 Fluffy, General condensed metal 880 730 65 Condensed Good metal, easily collected 780 650 40 Condensed Poor metal, uneasily collected
It can be seen from the tests that a condensed metal of the magnesium-lithium alloy, formed when the temperature of the first condensing chamber is 880° C. and the temperature of the second condensing chamber is 65° C., is the best and easily collected. When the temperatures of the first and second condensing chambers are high, the magnesium-lithium alloy is fluffy and has the general form. If the temperatures of the first and second condensing chambers are too low, the formed condensed metal is collected uneasily, and cannot form the briquettes.

Experiment 2

[0040] Raw materials and method steps in Embodiment 1 are used for experiments, which only changes reduction conditions, and other conditions are the same as Embodiment 1, so that the influences of different reduction conditions on the present application are tested. The specific test conditions and results are below:

TABLE-US-00006 Reduction Reduction Magnesium- temper- Reduction vacuum Li Mg lithium ature time degree reduction reduction alloy (° C.) (min) (pa) rate (%) rate (%) uniformity 1000 600 3 62.1 48.5 Poor 1100 480 2 79.3 61.5 Rather Poor 1100 600 4 96.1 71.1 Rather good 1190 480 5 87.2 83.1 Rather good 1190 600 2 99.2 95.1 Excellent

[0041] We can see the table that the product reduction rate reaches 99.2% and the Mg reduction rate reaches 95.1% when the reduction temperature is 1,190° C. and the reduction time is 10 h. The reduction temperature is lowered to cause biased proportion of the magnesium-lithium alloy and decrease of reduction rate and yield, thereby increasing the manufacture cost.

Experiment 3

[0042] Raw materials and method steps in Embodiment 1 are used for experiment, which only changes the temperatures of the distiller in a refining step, and other conditions are the same as Embodiment

1. Specific test conditions and results are as follows:
Refining test conditions are shown in the table below:

TABLE-US-00007 Temperature Mixing Argon 99.99% Synthesized (° C.) time (min) (Mpa) ingot 780 15 0.2 1# 680 30 0.2 2# 580 60 0.2 3#
The magnesium-lithium alloy results are shown in the table below:

TABLE-US-00008 1# Mg Li Fe Ni Cu Al Mn Phase analysis 90.2002 9.3 0.02 0.003 0.005 0.03 0.025 Stable α + β phase, Ti Ca Si Zn K Na Others uniformly distributed 0.005 0.043 0.15 0.0008 0.03 0.18 0.008 phase composition 2# Mg Li Fe Ni Cu Al Mn Stable α + β phase, 91.1239 8.3 0.02 0.0031 0.0051 0.03 0.024 Ti Ca Si Zn K Na Others 0.048 0.045 0.145 0.0009 0.025 0.18 0.05 3# Mg Li Fe Ni Cu Al Mn Stable α + β phase, 91.8741 7.5 0.02 0.0029 0.0053 0.03 0.026 with defects locally Ti Ca Si Zn K Na Others 0.052 0.041 0.148 0.0007 0.03 0.18 0.09

[0043] According to the table, we can see that the rather ideal smelting temperature is reached after stirring for 15 min at the temperature of 780° C. in the presence of 99.99% argon, so that the melt-casted magnesium-lithium alloy is not segregated and the stable α+β phase is formed; if the magnesium-lithium alloy is segregated unstably due to too low temperature, oxides in the product will increase.

[0044] Those skilled in the art should be able to implement or use the present invention according to the description of the embodiments disclosed above. Various amendments to these embodiments will be obvious to those skilled in the art. The general principle defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention will not be intended to be limited to these embodiments herein, and the broadest scope consistent with the principles and novel features disclosed herein shall prevail.