Electrolytic tank and method for preparing aluminum alloy through low-temperature molten salt electrolysis

Abstract

The invention belongs to the technical field of molten salt electrolysis, and particularly relates to an electrolytic bath and method for preparing aluminum alloy through low-temperature molten salt electrolysis. The electrolytic cell comprises a cell shell, a cover plate, a heat preservation layer, a bottom insulation layer, an auxiliary heating device, a gas recovery device, a cathode guide rod, an anode guide rod, a consumable cathode and an anode lining, according to the method, chlorate is used as a molten salt system, chlorides of alloy elements are used as raw materials, and solid aluminum is used as a consumable cathode for electrolysis. In the electrolysis process, alloy elements are separated out on the surface of cathode solid aluminum and are alloyed with an aluminum matrix to form the aluminum alloy, and aluminum alloys with different components can be prepared by controlling the electrolysis temperature and components of a fused salt system.

Description

Technical Field

[0001] The present invention belongs to the technical field of molten salt electrolysis, and in particular relates to an electrolytic cell and a method for preparing aluminum alloy by low-temperature molten salt electrolysis. Background Art

[0002] Aluminum alloys have good material properties such as light weight, good shock absorption, high specific strength, high cutting stability, good biocompatibility, and corrosion resistance. They are widely used in the fields of automobiles, aerospace, national defense, biomedicine, and electronic components. At present, aluminum alloys are mainly produced by mixing aluminum with other elements in a certain proportion in a molten state. The production of aluminum alloys using this method has the advantages of simple equipment, mature technology, and easy operation, but there are also many problems: (1) The production process is cumbersome: Before production, metallic aluminum and alloying elements must be obtained through their own metallurgical processes, and then the target alloy is obtained through secondary or even multiple smelting; (2) The metal burnout rate is high: oxidation burnout is serious during the heating and smelting process; especially for some highly active alloying elements, such as magnesium and lithium, the production cost of aluminum alloys is relatively high; (3) High energy consumption and severe environmental pollution.

[0003] Many aluminum alloys, such as aluminum-magnesium and aluminum-lithium alloys, can also be produced by molten salt electrolysis. However, the traditional molten salt electrolysis method for producing aluminum-magnesium alloys uses fluoride as the molten salt system, magnesium oxide as the raw material, and aluminum liquid as the cathode electrolysis. Although magnesium oxide is cheap and has the advantage of low cost, its solubility in fluoride salts is low, the magnesium content in the produced aluminum-magnesium alloy is low, and the anode effect is prone to occur during the electrolysis process, the current efficiency is low, and the energy consumption is high. The molten salt electrolysis method for producing aluminum-lithium alloys uses chloride as the molten salt system, lithium chloride or lithium carbonate as the raw material, and aluminum liquid as the cathode electrolysis. Using lithium carbonate as a raw material can significantly reduce the cell voltage, but lithium carbonate has poor solubility in chloride molten salts, and is prone to produce elemental carbon after long-term electrolysis, affecting the continuous operation of electrolysis. In view of the above disadvantages, researchers have been exploring more economical and environmentally friendly methods for producing aluminum alloys. Summary of the invention

[0004] In view of the above problems, the present invention proposes an electrolytic cell and method for preparing aluminum alloy by low-temperature molten salt electrolysis. The method uses chloride salt as the molten salt system, chloride of alloying elements as raw materials, and solid aluminum as a consumable cathode for electrolysis. During the electrolysis process, the alloying elements are precipitated on the surface of the cathode solid aluminum and alloyed with the aluminum matrix to form an aluminum alloy. Aluminum alloys of different compositions can be prepared by controlling the electrolysis temperature and the components of the molten salt system.

[0005] The technical solution of the present invention is: An electrolytic cell for preparing aluminum alloy by low-temperature molten salt electrolysis, the electrolytic cell comprising a cell shell, a cover plate, a thermal insulation layer, a bottom insulating layer, an auxiliary heating device, a gas recovery device, a cathode guide rod, an anode guide rod, a consumable cathode and an anode liner; the outermost part of the electrolytic cell is the cell shell, a thermal insulation layer is provided close to the inner wall of the cell shell, a cover plate is provided on the top of the cell shell, a liquid aluminum alloy water outlet, a cathode guide rod opening and a gas recovery device opening are reserved on the cover plate, a bottom insulating layer and an anode liner are provided in the thermal insulation layer, the anode liner is attached to the side wall of the thermal insulation layer, the bottom of the anode liner is connected to the bottom insulating layer and sealed by masonry, the anode guide rod is connected to the anode liner, and the consumable cathode is connected to the cathode guide rod by means of a thread; the gas recovery device is located at the gas recovery device opening of the cover plate, and a liquid aluminum alloy water outlet cover plate is provided at the liquid aluminum alloy water outlet; a molten electrolyte with a height of 50-100 cm is provided inside the electrolytic cell, and an auxiliary heating device is provided at the side of the electrolytic cell 30-60 cm away from the cover plate to control the electrolysis temperature.

[0006] Furthermore, the above-mentioned electrolytic cell for preparing aluminum alloy by low-temperature molten salt electrolysis, the electrolytic cell is in the shape of a cylinder or a cuboid; the cell shell is made of steel plate, the thickness of the steel plate is 5-10mm; the insulation layer is built by one or more of mullite bricks, clay bricks, alumina bricks, and calcium silicate boards, and the thickness of the insulation layer is 20-40cm; the upper layer of the cover plate is a steel plate, and the lower layer is an insulation material, the insulation material is made of one of alumina, mullite, calcium silicate, and clay, and the thickness of the cover plate is 10-20cm.

[0007] Furthermore, in the above-mentioned electrolytic cell for preparing aluminum alloy by low-temperature molten salt electrolysis, the cover plate is in a closed state when liquid aluminum alloy is not discharged or the consumable cathode does not need to be replaced, and can be opened to discharge liquid aluminum alloy and replace the consumable cathode when liquid aluminum alloy is discharged or the consumable cathode needs to be replaced.

[0008] Furthermore, in the above-mentioned electrolytic cell for preparing aluminum alloy by low-temperature molten salt electrolysis, the anode lining is made of carbonaceous material, with a height of 30-100 cm and a thickness of 5-10 cm, and the carbonaceous material is petroleum coke, graphite or calcined anthracite; the bottom insulating layer connected to the anode lining is made of one of corundum, silicon nitride combined with silicon carbide or alumina, with a thickness of 5-10 cm and a height of 10-40 cm; the consumable cathode is made of pure aluminum, with a cylindrical or rectangular shape, and is connected to the cathode guide rod by threading, and the pure aluminum is original aluminum obtained by electrolysis; the anode guide rod is connected to the anode lining by threading or ferrophosphorus casting, and after the connection is completed, the anode guide rod mouth is sealed and insulated.

[0009] Furthermore, in the above-mentioned electrolytic cell for preparing aluminum alloy by low-temperature molten salt electrolysis, during the electrolysis process, the metal electrochemically generated by the consumable cathode is first generated on the consumable cathode aluminum and reacts with the aluminum to form an alloy of the metal and aluminum. As the electrolysis proceeds, the content of the element in the aluminum alloy increases. When the melting point of the alloy is reached, the molten alloy drips from the surface of the consumable cathode aluminum to the bottom of the electrolytic cell to form an aluminum alloy molten pool. When the consumable cathode aluminum is consumed to a certain extent, the consumable cathode is replaced; when the stock of the aluminum alloy molten pool at the bottom reaches a certain amount, a vacuum ladle is used to extract part of the aluminum alloy melt from the bottom of the electrolytic cell, and the extracted aluminum alloy is cast into ingots after simple refining and used as a mother alloy of the aluminum alloy; during the electrolysis process, the electrolysis temperature in the electrolytic cell is controlled by an auxiliary heating device, thereby controlling the content of alloying elements in the generated aluminum alloy.

[0010] A method for preparing aluminum alloy by low-temperature molten salt electrolysis, wherein after the electrolytic cell is built, it is first heated to above 600°C by gas, then the electrolyte is heated to the electrolysis temperature outside the electrolytic cell, melted and poured into the electrolytic cell, a consumable cathode aluminum ingot or aluminum plate is installed on the electrolytic cell, the electrolytic cell is sealed, and power is turned on for electrolysis; during the electrolysis process, raw materials are added to the molten electrolyte in a molten state or a solid state every 0.5h according to the current intensity of the electrolytic cell, the consumable cathode is replaced every 10-48h, and the aluminum alloy is taken out from the bottom of the electrolytic cell by vacuum lifting every 5-36h, ensuring that the liquid surface of the liquid aluminum alloy is 2-5cm away from the bottom of the anode inner substrate; the cathode residual electrode mainly contains aluminum and alloy elements, and the cathode residual electrode is remelted and recast into a consumable cathode for recycling; During the electrolysis process, the electrolyte components and electrolysis processes used are different depending on the type of aluminum alloy to be prepared.

[0011] Furthermore, in the above-mentioned method for preparing aluminum alloy by low-temperature molten salt electrolysis, when preparing aluminum-magnesium alloy, magnesium chloride is used as raw material, and the molten salt electrolyte used for electrolysis is a chloride molten salt system mainly composed of NaCl-KCl-MgCl2, MgCl2-KCl and MgCl2-NaCl, and alkali metal or alkaline earth metal chlorides CaCl2 and LiCl can also be added. The molar percentage of each substance in the electrolyte is NaCl: 20-80%, KCl: 20-80%, MgCl2: 0-40%, CaCl2: 0-20%, LiCl: 0-20%; the initial crystallization temperature of the electrolyte is controlled at 400-600°C, and during the electrolysis process, the electrolysis temperature is 450-640°C, and the anode lining current density is 0.2-0.7A / cm 2During electrolysis, the consumable cathode aluminum is suspended in the molten salt electrolyte in a solid form, magnesium chloride is electrolyzed into metallic magnesium, and metallic magnesium is precipitated on the surface of the consumable cathode aluminum and combined with aluminum to form an aluminum-magnesium alloy. When the magnesium content in the aluminum-magnesium alloy is 0-70 wt.%, the aluminum-magnesium alloy drips to the bottom of the electrolytic cell in a liquid state; during the electrolysis process, an aluminum-magnesium alloy with a magnesium content of 0-70 wt.% is prepared by adjusting the electrolyte composition and the electrolysis temperature; the aluminum-magnesium alloy melt obtained at the bottom of the electrolytic cell is taken out from the electrolytic cell by a vacuum ladle, and the aluminum-magnesium alloy taken out from the electrolytic cell is poured into a mixing furnace for refining to obtain an aluminum-magnesium intermediate alloy, and the aluminum-magnesium intermediate alloy can be used to prepare various types of aluminum alloys after being diluted with aluminum and alloying elements.

[0012] Furthermore, in the above-mentioned method for preparing aluminum alloy by low-temperature molten salt electrolysis, when preparing aluminum-lithium alloy, lithium chloride is used as raw material, and the molten salt electrolyte used for electrolysis is an alkali metal chloride molten salt system mainly composed of NaCl-KCl-LiCl, LiCl-KCl and LiCl-NaCl, and the molar percentage of each substance in the electrolyte is NaCl: 20-80%, KCl: 10-80%, LiCl: 20-50%, and the primary crystallization temperature of the electrolyte is controlled at 550-600°C. During the electrolysis process, the electrolysis temperature is 590-650°C, and the anode lining current density is 0.2-0.7A / cm 2 During electrolysis, the consumable cathode aluminum is suspended in the molten salt electrolyte in a solid form, lithium chloride is electrolyzed into metallic lithium, metallic lithium is precipitated on the surface of the consumable cathode aluminum and combines with aluminum to form an aluminum-lithium alloy. When the lithium content in the aluminum-lithium alloy is 0-10wt.%, the aluminum-lithium alloy drips to the bottom of the electrolytic cell in a liquid state. During the electrolysis process, an aluminum-lithium alloy with a lithium content of 0-10 wt.% is prepared by adjusting the electrolyte composition and the electrolysis temperature. The aluminum-lithium alloy melt obtained at the bottom of the electrolytic cell is taken out from the electrolytic cell by vacuum ladle, and the aluminum-lithium alloy taken out from the electrolytic cell is poured into a mixing furnace for refining to obtain an aluminum-lithium intermediate alloy. The aluminum-lithium intermediate alloy can be used to prepare various types of aluminum alloys after being diluted with aluminum and alloying elements.

[0013] Furthermore, in the above-mentioned method for preparing aluminum alloy by low-temperature molten salt electrolysis, zinc chloride is used as a raw material when preparing aluminum-zinc alloy, and the molten salt electrolyte used for electrolysis is a chloride molten salt system mainly composed of NaCl-KCl-ZnCl2, ZnCl2-NaCl and ZnCl2-KCl, and the molar percentage of each substance in the electrolyte is NaCl: 20-80%, KCl: 10-80%, ZnCl2: 10-25%; the initial crystallization temperature of the electrolyte is controlled at 350-550°C; during the electrolysis process, the electrolysis temperature is 350-550°C, and the anode lining current density is 0.2-0.7 A / cm 2During electrolysis, the consumable cathode aluminum is suspended in the molten salt electrolyte in a solid form, and zinc chloride is electrolyzed into metallic zinc. The metallic zinc precipitates on the surface of the consumable cathode aluminum and combines with the aluminum to form an aluminum-zinc alloy. When the zinc content in the aluminum-zinc alloy is 0-80 wt.%, the aluminum-zinc alloy drips to the bottom of the electrolytic cell in a liquid state. During the electrolysis process, an aluminum-zinc alloy with a zinc content of 0-80 wt.% is prepared by adjusting the electrolyte composition and the electrolysis temperature.

[0014] Furthermore, in the above-mentioned method for preparing aluminum alloy by low-temperature molten salt electrolysis, when preparing aluminum-calcium alloy, calcium oxide is used as raw material, and the molten salt electrolyte used for electrolysis is a chloride molten salt system mainly composed of NaCl-KCl-CaCl2, CaCl2-NaCl and CaCl2-KCl, and the molar percentage of each substance in the electrolyte is NaCl: 20-70%, KCl: 10-70%, CaCl2: 20-70%, CaO: 1-10%; the initial crystallization temperature of the electrolyte is controlled at 450-550°C, and during the electrolysis process, the electrolysis temperature is 550-590°C, and the anode lining current density is 0.2-0.7 A / cm 2 During electrolysis, the consumable cathode aluminum is suspended in the molten salt electrolyte in a solid form, and calcium oxide is electrolyzed into metallic calcium. The metallic calcium precipitates on the surface of the consumable cathode aluminum and combines with aluminum to form an aluminum-calcium alloy. When the calcium content in the aluminum-calcium alloy reaches more than 40%, the aluminum-calcium alloy drips to the bottom of the electrolytic cell in a liquid state. During the electrolysis process, an aluminum-calcium alloy with a calcium content of more than 40 wt.% is prepared by adjusting the electrolyte composition and the electrolysis temperature.

[0015] Advantages and beneficial effects of the present invention: The method used to prepare aluminum-magnesium, aluminum-lithium alloys, aluminum-zinc alloys, and aluminum-calcium alloys has the advantages of low energy consumption, high and controllable magnesium / lithium content in the alloy, less loss of metal magnesium / lithium, uniform composition, and low cost. The produced alloy can be added with alloying elements after simple refining to prepare various types of aluminum alloy products. In addition, the method can also be applied to the production of other aluminum alloys. The low-temperature molten salt electrolysis used in this project to prepare aluminum alloys has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a front schematic diagram of the rectangular electrolytic cell structure of the present invention; Figure 2 A top view (AA) of the rectangular electrolytic cell structure of the present invention; Figure 3 A top view (BB) of the rectangular electrolytic cell structure of the present invention; Figure 4 It is a front schematic diagram of the cylindrical electrolytic cell structure of the present invention; Figure 5A top view (AA) of the cylindrical electrolytic cell structure of the present invention; Figure 6 A top view (BB) of the cylindrical electrolytic cell structure of the present invention; In the figure, 1-liquid aluminum alloy outlet cover plate; 2-cathode guide rod; 3-gas collection device; 4-anode lining; 5-cover plate; 6-insulation layer; 7-auxiliary heating device; 8-electrolyte; 9-liquid aluminum alloy; 10-bottom insulation layer; 11-tank shell; 12-anode guide rod; 13-consumable cathode. DETAILED DESCRIPTION

[0017] Next, the specific implementation mode of the present invention is further described in detail in conjunction with the drawings and examples of the specification. The purity of LiCl, NaCl, KCl and MgCl2 used in the following examples is ≥98%. The following examples are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0018] Example 1

[0019] This invention provides an electrolytic cell for preparing aluminum alloy by low-temperature molten salt electrolysis. Figure 1-3 As shown, the electrolytic cell comprises a cell shell 11, a cover plate 5, a thermal insulation layer 6, a bottom insulating layer 10, an auxiliary heating device 7, a gas recovery device 3, a cathode guide rod 2, an anode guide rod 12, a consumable cathode 13 and an anode liner 4; the electrolytic cell is in the shape of a rectangular parallelepiped, the outermost part of the electrolytic cell is the cell shell 11, a thermal insulation layer 6 is provided close to the inner wall of the cell shell 11, a cover plate 5 is provided on the top of the cell shell 11, and a liquid aluminum alloy outlet, a cathode guide rod outlet and a gas recovery device outlet are reserved on the cover plate 5. , a bottom insulating layer 10 and an anode liner 4 are provided in the insulation layer 6, the anode liner 4 is attached to the side wall of the insulation layer 6, the bottom of the anode liner 4 is connected to the bottom insulating layer 10 and sealed by masonry, the anode guide rod 12 is connected to the anode liner 4, and the consumable cathode 13 is connected to the cathode guide rod 12 by means of threads; the gas recovery device 3 is located at the gas recovery device port of the cover plate 5, and a liquid aluminum alloy outlet cover 1 plate is provided at the liquid aluminum alloy outlet; a molten electrolyte with a height of 50 cm is provided inside the electrolytic cell, and an auxiliary heating device 7 is provided on the side of the electrolytic cell 30 cm below the cover plate 5 to control the electrolysis temperature; The tank shell 11 is made of steel plate with a thickness of 5 mm; the insulation layer is made of mullite bricks with a thickness of 20 cm; the upper layer of the cover plate 5 is a steel plate, and the lower layer is an insulation material made of alumina, and the thickness of the cover plate 5 is 10 cm; The cover plate 5 is in a closed state when the liquid aluminum alloy is not discharged or the consumable cathode 13 does not need to be replaced, and can be opened to discharge the liquid aluminum alloy or replace the consumable cathode 13 when the liquid aluminum alloy is discharged or the consumable cathode 13 is replaced; The anode lining 4 is made of carbonaceous material, with a height of 30 cm and a thickness of 5 cm, and the carbonaceous material is petroleum coke; the bottom insulating layer 10 connected to the anode lining 4 is made of corundum, with a thickness of 5 cm and a height of 10 cm; the consumable cathode 13 is made of pure aluminum, in the shape of a rectangular parallelepiped, and is connected to the cathode guide rod 2 by means of threads, and the pure aluminum is original aluminum obtained by electrolysis; the anode guide rod 12 is connected to the anode lining 4 by means of threads, and after the connection is completed, the anode guide rod mouth is sealed and insulated.

[0020] Example 2

[0021] This invention provides an electrolytic cell for preparing aluminum alloy by low-temperature molten salt electrolysis. Figure 4-6 As shown, the electrolytic cell comprises a cell shell 11, a cover plate 5, a thermal insulation layer 6, a bottom insulating layer 10, an auxiliary heating device 7, a gas recovery device 3, a cathode guide rod 2, an anode guide rod 12, a consumable cathode 13 and an anode liner 4; the electrolytic cell is cylindrical in shape, the outermost part of the electrolytic cell is the cell shell 11, a thermal insulation layer 6 is provided close to the inner wall of the cell shell 11, a cover plate 5 is provided on the top of the cell shell 11, and a liquid aluminum alloy outlet, a cathode guide rod outlet and a gas recovery device outlet are reserved on the cover plate 5. , a bottom insulating layer 10 and an anode liner 4 are provided in the insulation layer 6, the anode liner 4 is attached to the side wall of the insulation layer 6, the bottom of the anode liner 4 is connected to the bottom insulating layer 10 and sealed by masonry, the anode guide rod 12 is connected to the anode liner 4, and the consumable cathode 13 is connected to the cathode guide rod 12 by means of threads; the gas recovery device 3 is located at the gas recovery device port of the cover plate 5, and a liquid aluminum alloy outlet cover 1 plate is provided at the liquid aluminum alloy outlet; a molten electrolyte with a height of 50 cm is provided inside the electrolytic cell, and an auxiliary heating device 7 is provided on the side of the electrolytic cell 30 cm below the cover plate 5 to control the electrolysis temperature; The tank shell 11 is made of steel plate with a thickness of 5 mm; the insulation layer is made of clay bricks with a thickness of 20 cm; the upper layer of the cover plate 5 is a steel plate, and the lower layer is an insulation material made of mullite, and the thickness of the cover plate 5 is 10 cm; The cover plate 5 is in a closed state when the liquid aluminum alloy is not discharged or the consumable cathode 13 does not need to be replaced, and can be opened to discharge the liquid aluminum alloy or replace the consumable cathode 13 when the liquid aluminum alloy is discharged or the consumable cathode 13 is replaced; The anode lining 4 is made of carbonaceous material, with a height of 30 cm and a thickness of 5 cm, and the carbonaceous material is graphite; the bottom insulating layer 10 connected to the anode lining 4 is made of corundum, with a thickness of 5 cm and a height of 10 cm; the consumable cathode 13 is made of pure aluminum, with a cylindrical shape, and is connected to the cathode guide rod 2 by threading, and the pure aluminum is original aluminum obtained by electrolysis; the anode guide rod 12 is connected to the anode lining 4 by ferrophosphorus casting, and after the connection is completed, the anode guide rod mouth is sealed and insulated.

[0022] Example 3

[0023] This embodiment is a method for preparing aluminum-magnesium alloy using the electrolytic cell of embodiment 1, and the specific steps of the method are: The molten salt system was prepared according to 40 MgCl2-32.5 KCl- 27.5NaCl (mol %), and an aluminum plate with a thickness of 5 mm was used as a consumable cathode; After the electrolytic cell is built, it is first heated to 600℃ by gas. Then, the electrolyte is heated to the electrolysis temperature outside the electrolytic cell and melted and poured into the electrolytic cell. The consumable cathode is installed on the electrolytic cell, the electrolytic cell is sealed, and the power is turned on for electrolysis. During the electrolysis process, the initial crystal temperature of the electrolyte is controlled at 450℃, the electrolysis temperature is controlled at 475℃, and the current density of the anode lining is 0.2 A / cm 2 The electrolysis time is 3 h, and the raw material MgCl2 is added to the molten electrolyte in a molten state every 0.5 h. The consumable cathode is replaced every 10 h. The aluminum alloy is taken out from the bottom of the electrolytic cell by vacuum lifting every 5 h, ensuring that the liquid aluminum alloy is 2 cm away from the bottom of the anode inner substrate. After the electrolysis was completed, the aluminum-magnesium alloy at the bottom of the electrolytic cell was taken out and ultrasonically cleaned. The weight percentage of magnesium was measured to be 34.1%.

[0024] Example 4

[0025] This embodiment is a method for preparing aluminum-magnesium alloy using the electrolytic cell of embodiment 1, and the specific steps of the method are: The molten salt system was prepared according to 25 MgCl2-55 KCl- 20NaCl (mol %), and an aluminum plate with a thickness of 5 mm was used as a consumable cathode; After the electrolytic cell is built, it is first heated to 600°C by gas, and then the electrolyte is heated to the electrolysis temperature outside the electrolytic cell and melted and poured into the electrolytic cell. The consumable cathode is installed on the electrolytic cell, the electrolytic cell is sealed, and the electrolysis is carried out by power. During the electrolysis process, the initial crystal temperature of the electrolyte is controlled at 530°C, the electrolysis temperature is controlled at 550°C, and the current density of the anode lining is 0.2 A / cm 2 , the electrolysis time is 3 h, the raw material MgCl2 is added to the molten electrolyte in molten or solid form every 0.5 h, the consumable cathode is replaced every 10 h, and the aluminum alloy is taken out from the bottom of the electrolytic cell by vacuum lifting every 5 h, ensuring that the liquid aluminum alloy is 2 cm away from the bottom of the anode inner substrate; After the electrolysis was completed, the aluminum-magnesium alloy at the bottom of the electrolytic cell was taken out and ultrasonically cleaned. The weight percentage of magnesium was measured to be 19.8%.

[0026] Example 5

[0027] This embodiment is a method for preparing aluminum-lithium alloy using the electrolytic cell of embodiment 1, and the specific steps of the method are: The molten salt system was prepared according to 40LiCl-60KCl (mol%), and an aluminum plate with a thickness of 5 mm was used as a consumable cathode; After the electrolytic cell is built, it is first heated to 600℃ by gas. Then, the electrolyte is heated to the electrolysis temperature outside the electrolytic cell and melted and poured into the electrolytic cell. The consumable cathode is installed on the electrolytic cell, the electrolytic cell is sealed, and the electrolysis is carried out by power. During the electrolysis process, the initial crystal temperature of the electrolyte is controlled at 580℃, the electrolysis temperature is controlled at 600℃, and the current density of the anode lining is 0.3 A / cm 2 The electrolysis time is 3 h, the raw material LiCl is added to the molten electrolyte in a molten state every 0.5 h, the consumable cathode is replaced every 10 h, and the aluminum alloy is taken out from the bottom of the electrolytic cell by vacuum lifting every 5 h, ensuring that the liquid aluminum alloy is 2 cm away from the bottom of the anode inner substrate; After the electrolysis was completed, the aluminum-lithium alloy at the bottom of the electrolytic cell was taken out and after ultrasonic cleaning, the weight percentage of lithium was measured to be 9.3%.

[0028] Example 6

[0029] This embodiment is a method for preparing aluminum-lithium alloy using the electrolytic cell of embodiment 1, and the specific steps of the method are: The molten salt system was prepared according to 30 LiCl-70NaCl (mol %), and an aluminum plate with a thickness of 5 mm was used as a consumable cathode; After the electrolytic cell is built, it is first heated to 600°C by gas, and then the electrolyte is heated to the electrolysis temperature outside the electrolytic cell and melted and poured into the electrolytic cell. The consumable cathode is installed on the electrolytic cell, the electrolytic cell is sealed, and the power is turned on for electrolysis. During the electrolysis process, the initial crystal temperature of the electrolyte is controlled at 620°C, the electrolysis temperature is controlled at 640°C, and the current density of the anode lining is 0.3 A / cm 2 The electrolysis time is 3 h, the raw material LiCl is added to the molten electrolyte in a molten state every 0.5 h, the consumable cathode is replaced every 10 h, and the aluminum alloy is taken out from the bottom of the electrolytic cell by vacuum lifting every 5 h, ensuring that the liquid aluminum alloy is 2 cm away from the bottom of the anode inner substrate; After the electrolysis was completed, the aluminum-lithium alloy at the bottom of the electrolytic cell was taken out and after ultrasonic cleaning, the weight percentage of lithium was measured to be 3.8%.

[0030] Example 7

[0031] This embodiment is a method for preparing aluminum-zinc alloy using the electrolytic cell of embodiment 1, and the specific steps of the method are: The molten salt system was prepared according to 20 ZnCl2- 40NaCl-40KCl (mol %), and an aluminum plate with a thickness of 5 mm was used as a consumable cathode; After the electrolytic cell is built, it is first heated to 600℃ by gas, and then the electrolyte is heated to the electrolysis temperature outside the electrolytic cell and melted and poured into the electrolytic cell. The consumable cathode is installed on the electrolytic cell, the electrolytic cell is sealed, and the power is turned on for electrolysis. During the electrolysis process, the initial crystal temperature of the electrolyte is controlled at 520℃, the electrolysis temperature is controlled at 550℃, and the current density of the anode lining is 0.3 A / cm 2 The electrolysis time is 3 h, the raw material ZnCl2 is added to the molten electrolyte in a molten state every 0.5 h, the consumable cathode is replaced every 10 h, and the aluminum alloy is taken out from the bottom of the electrolytic cell by vacuum lifting every 5 h, ensuring that the liquid aluminum alloy is 2 cm away from the bottom of the anode inner substrate; After the electrolysis was completed, the aluminum-zinc alloy at the bottom of the electrolytic cell was taken out and after ultrasonic cleaning, the weight percentage of zinc was measured to be 74.6%.

[0032] Example 8

[0033] This embodiment is a method for preparing aluminum-calcium alloy using the electrolytic cell of embodiment 1, and the specific steps of the method are: The molten salt system was prepared according to 48 CaCl2- 50NaCl-2CaO (mol %), and an aluminum plate with a thickness of 5 mm was used as a consumable cathode; After the electrolytic cell is built, it is first heated to 600°C by gas, and then the electrolyte is heated to the electrolysis temperature outside the electrolytic cell and melted and poured into the electrolytic cell. The consumable cathode is installed on the electrolytic cell, the electrolytic cell is sealed, and the power is turned on for electrolysis. During the electrolysis process, the initial crystal temperature of the electrolyte is controlled at 510°C, the electrolysis temperature is controlled at 550°C, and the current density of the anode lining is 0.3 A / cm 2 The electrolysis time is 3 h, raw material CaCl2 is added to the molten electrolyte in molten form every 0.5 h, the consumable cathode is replaced every 10 h, and the aluminum alloy is taken out from the bottom of the electrolytic cell by vacuum lifting every 5 h, ensuring that the liquid aluminum alloy is 2 cm away from the bottom of the anode inner substrate; After the electrolysis was completed, the aluminum-calcium alloy at the bottom of the electrolytic cell was taken out and ultrasonically cleaned. The weight percentage of calcium was measured to be 62.7%.

Claims

1. An electrolytic cell for preparing aluminum alloy by low-temperature molten salt electrolysis, characterized in that: The electrolytic cell comprises a cell shell, a cover plate, a heat preservation layer, a bottom insulating layer, an auxiliary heating device, a gas recovery device, a cathode guide rod, an anode guide rod, a consumable cathode and an anode lining; the outermost part of the electrolytic cell is the cell shell, a heat preservation layer is arranged close to the inner wall of the cell shell, a cover plate is arranged on the top of the cell shell, a liquid aluminum alloy water outlet, a cathode guide rod opening and a gas recovery device opening are reserved on the cover plate, a bottom insulating layer and an anode lining are arranged in the heat preservation layer, the anode lining is attached to the side wall of the heat preservation layer, the bottom of the anode lining is connected to the bottom insulating layer and sealed by masonry, the anode guide rod is connected to the anode lining, and the consumable cathode is connected to the cathode guide rod by means of a thread; the gas recovery device is located at the gas recovery device opening of the cover plate, and a liquid aluminum alloy water outlet cover plate is arranged at the liquid aluminum alloy water outlet; a molten electrolyte with a height of 50-100 cm is arranged inside the electrolytic cell, and an auxiliary heating device is arranged at the side of the electrolytic cell 30-60 cm away from the cover plate to control the electrolysis temperature.

2. The electrolytic cell for preparing aluminum alloy by low-temperature molten salt electrolysis according to claim 1, characterized in that: The electrolytic cell is cylindrical or rectangular in shape; the cell shell is made of steel plate with a thickness of 5-10 mm; the insulation layer is built of one or more of mullite bricks, clay bricks, alumina bricks, and calcium silicate boards with a thickness of 20-40 cm; the upper layer of the cover plate is a steel plate, and the lower layer is an insulation material, the insulation material is made of one of alumina, mullite, calcium silicate, and clay, and the cover plate is 10-20 cm thick.

3. The electrolytic cell for preparing aluminum alloy by low-temperature molten salt electrolysis according to claim 2, characterized in that: The cover plate is in a closed state when the liquid aluminum alloy is not discharged or the consumable cathode does not need to be replaced, and can be opened to discharge the liquid aluminum alloy and replace the consumable cathode when the liquid aluminum alloy is discharged or the consumable cathode is replaced.

4. The electrolytic cell for preparing aluminum alloy by low-temperature molten salt electrolysis according to claim 1, characterized in that: The anode lining is made of carbonaceous material, with a height of 30-100cm and a thickness of 5-10cm. The carbonaceous material is petroleum coke, graphite or calcined anthracite. The bottom insulating layer connected to the anode lining is made of one of corundum, silicon nitride combined with silicon carbide or alumina, with a thickness of 5-10cm and a height of 10-40cm. The consumable cathode is made of pure aluminum, with a cylindrical or rectangular shape, and is connected to the cathode guide rod by threading. The pure aluminum is original aluminum obtained by electrolysis. The anode guide rod is connected to the anode lining by threading or ferrophosphorus casting. After the connection is completed, the anode guide rod mouth is sealed and insulated.

5. The electrolytic cell for preparing aluminum alloy by low-temperature molten salt electrolysis according to claim 4, characterized in that: During the electrolysis process, the metal electrochemically generated by the consumable cathode is first generated on the consumable cathode aluminum and reacts with the aluminum to form an alloy of the metal and aluminum. As the electrolysis proceeds, the content of the element in the aluminum alloy increases. When the melting point of the alloy is reached, the alloy melts and drips from the surface of the consumable cathode aluminum to the bottom of the electrolytic cell to form an aluminum alloy molten pool. When the consumable cathode aluminum is consumed to a certain extent, the consumable cathode is replaced. When the stock of aluminum alloy molten pool at the bottom reaches a certain amount, a part of the aluminum alloy melt is extracted from the bottom of the electrolytic cell by using a vacuum ladle. The extracted aluminum alloy is cast into ingots after simple refining and used as the mother alloy of aluminum alloy. During the electrolysis process, the electrolysis temperature in the electrolytic cell is controlled by an auxiliary heating device, thereby controlling the content of alloying elements in the generated aluminum alloy.

6. A method for preparing aluminum alloy by low-temperature molten salt electrolysis, characterized in that: After the electrolytic cell is built, it is first heated to above 600°C by gas, and then the electrolyte is heated to the electrolysis temperature outside the electrolytic cell and melted and poured into the electrolytic cell. The consumable cathode aluminum ingot or aluminum plate is installed on the electrolytic cell, the electrolytic cell is sealed, and the electrolysis is carried out by powering on. During the electrolysis process, according to the current intensity of the electrolytic cell, raw materials are added to the molten electrolyte in a molten state or a solid state every 0.5 h, the consumable cathode is replaced every 10-48 h, and the aluminum alloy is taken out from the bottom of the electrolytic cell by vacuum lifting every 5-36 h, ensuring that the liquid surface of the liquid aluminum alloy is 2-5 cm away from the bottom of the anode inner substrate. The main components of the cathode residual electrode are aluminum and alloy elements, and the cathode residual electrode is remelted and re-cast into a consumable cathode for recycling. During the electrolysis process, the electrolyte components and electrolysis processes used are different depending on the type of aluminum alloy to be prepared.

7. The method for preparing aluminum alloy by low-temperature molten salt electrolysis according to claim 6, characterized in that: When preparing aluminum-magnesium alloy, magnesium chloride is used as raw material, and the molten salt electrolyte used for electrolysis is a chloride molten salt system mainly composed of NaCl-KCl-MgCl2, MgCl2-KCl and MgCl2-NaCl. Alkali metal or alkaline earth metal chloride CaCl2 and LiCl can also be added. The molar percentage of each substance in the electrolyte is NaCl: 20~80%, KCl: 20~80%, MgCl2: 0~40%, CaCl2: 0~20%, LiCl: 0~20%; the initial crystallization temperature of the electrolyte is controlled at 400-600℃. During the electrolysis process, the electrolysis temperature is 450-640℃, and the anode lining current density is 0.2-0.7A / cm 2 During electrolysis, the consumable cathode aluminum is suspended in the molten salt electrolyte in a solid form, magnesium chloride is electrolyzed into metallic magnesium, and metallic magnesium is precipitated on the surface of the consumable cathode aluminum and combined with aluminum to form an aluminum-magnesium alloy. When the magnesium content in the aluminum-magnesium alloy is 0-70 wt.%, the aluminum-magnesium alloy drips to the bottom of the electrolytic cell in a liquid state; during the electrolysis process, an aluminum-magnesium alloy with a magnesium content of 0-70 wt.% is prepared by adjusting the electrolyte composition and the electrolysis temperature; the aluminum-magnesium alloy melt obtained at the bottom of the electrolytic cell is taken out from the electrolytic cell by a vacuum ladle, and the aluminum-magnesium alloy taken out from the electrolytic cell is poured into a mixing furnace for refining to obtain an aluminum-magnesium intermediate alloy, and the aluminum-magnesium intermediate alloy can be used to prepare various types of aluminum alloys after being diluted with aluminum and alloying elements.

8. The method for preparing aluminum alloy by low-temperature molten salt electrolysis according to claim 6, characterized in that: When preparing aluminum-lithium alloy, lithium chloride is used as raw material, and the molten salt electrolyte used for electrolysis is an alkali metal chloride molten salt system mainly composed of NaCl-KCl-LiCl, LiCl-KCl and LiCl-NaCl. The molar percentage of each substance in the electrolyte is NaCl: 20-80%, KCl: 10-80%, LiCl: 20-50%, and the primary crystallization temperature of the electrolyte is controlled at 550-600°C. During the electrolysis process, the electrolysis temperature is 590-650°C, and the anode lining current density is 0.2-0.7 A / cm 2 During electrolysis, the consumable cathode aluminum is suspended in the molten salt electrolyte in a solid form, lithium chloride is electrolyzed into metallic lithium, metallic lithium is precipitated on the surface of the consumable cathode aluminum and combines with aluminum to form an aluminum-lithium alloy. When the lithium content in the aluminum-lithium alloy is 0-10 wt.%, the aluminum-lithium alloy drips to the bottom of the electrolytic cell in a liquid state. During the electrolysis process, an aluminum-lithium alloy with a lithium content of 0-10 wt.% is prepared by adjusting the electrolyte composition and the electrolysis temperature. The aluminum-lithium alloy melt obtained at the bottom of the electrolytic cell is taken out from the electrolytic cell by vacuum ladle, and the aluminum-lithium alloy taken out from the electrolytic cell is poured into a mixing furnace for refining to obtain an aluminum-lithium intermediate alloy. The aluminum-lithium intermediate alloy can be used to prepare various types of aluminum alloys after being diluted with aluminum and alloying elements.

9. The method for preparing aluminum alloy by low-temperature molten salt electrolysis according to claim 6, characterized in that: When preparing aluminum-zinc alloy, zinc chloride is used as raw material, and the molten salt electrolyte used for electrolysis is a chloride molten salt system mainly composed of NaCl-KCl-ZnCl2, ZnCl2-NaCl and ZnCl2-KCl. The molar percentage of each substance in the electrolyte is NaCl: 20-80%, KCl: 10-80%, ZnCl2: 10-25%; the initial crystallization temperature of the electrolyte is controlled at 350-550°C; during the electrolysis process, the electrolysis temperature is 350-550°C, and the anode lining current density is 0.2-0.7A / cm 2 During electrolysis, the consumable cathode aluminum is suspended in the molten salt electrolyte in a solid form, and zinc chloride is electrolyzed into metallic zinc. The metallic zinc precipitates on the surface of the consumable cathode aluminum and combines with the aluminum to form an aluminum-zinc alloy. When the zinc content in the aluminum-zinc alloy is 0-80wt.%, the aluminum-zinc alloy drips to the bottom of the electrolytic cell in a liquid state. During the electrolysis process, an aluminum-zinc alloy with a zinc content of 0-80 wt.% is prepared by adjusting the electrolyte composition and the electrolysis temperature.

10. The method for preparing aluminum alloy by low-temperature molten salt electrolysis according to claim 6, characterized in that: When preparing aluminum-calcium alloy, calcium oxide is used as raw material, and the molten salt electrolyte used for electrolysis is a chloride molten salt system mainly composed of CaO-NaCl-KCl-CaCl2, CaO-CaCl2-NaCl and CaO-CaCl2-KCl. The molar percentage of each substance in the electrolyte is NaCl: 20-70%, KCl: 10-70%, CaCl2: 20-50%, CaO: 1-10%; the primary crystallization temperature of the electrolyte is controlled at 450-550°C. During the electrolysis process, the electrolysis temperature is 550-590°C, and the current density of the anode lining is 0.2-0.7 A / cm 2 During electrolysis, the consumable cathode aluminum is suspended in the molten salt electrolyte in a solid form, and calcium oxide is electrolyzed into metallic calcium. The metallic calcium precipitates on the surface of the consumable cathode aluminum and combines with aluminum to form an aluminum-calcium alloy. When the calcium content in the aluminum-calcium alloy reaches more than 40%, the aluminum-calcium alloy drips to the bottom of the electrolytic cell in a liquid state. During the electrolysis process, an aluminum-calcium alloy with a calcium content of more than 40 wt.% is prepared by adjusting the electrolyte composition and the electrolysis temperature.

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