Electrolytic cell for override recovery of pure aluminum from scrap aluminum and use method of electrolytic cell

Abstract

The invention belongs to the technical field of waste aluminum recovery, and particularly relates to an electrolytic cell for override recovery of pure aluminum from scrap aluminum and a use method of the electrolytic cell. The electrolytic cell comprises a scrap aluminum inlet cover plate, a scrap aluminum anode, a porous ceramic plate, a pure aluminum inlet and outlet cover plate, an electrolyte, an electrolytic cell cover plate, an electrolytic cell shell, a pure aluminum cathode, an electrolytic cell heat preservation layer, an electrolytic cell insulation layer, a cathode guide rod, a cathode graphite block, an insulation partition plate, an anode graphite block and an anode guide rod. Current enters the liquid scrap aluminum anode through the anode guide rod and the anode graphite block, then enters the liquid pure aluminum cathode through the molten electrolyte immersed in the scrap aluminum anode, the porous ceramic plate and the molten electrolyte in the cathode chamber in sequence, and finally is led out through the cathode graphite block and the cathode guide rod; in the electrolysis process, aluminum in the scrap aluminum anode is subjected to electrochemical dissolution, enters the molten electrolyte in the form of aluminum ions and moves to the liquid pure aluminum cathode through the molten electrolyte to be separated out.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste aluminum recovery, and specifically relates to an electrolytic cell for recovering pure aluminum from waste aluminum and a method for using the electrolytic cell. Background Art

[0002] Aluminum electrolysis is a high-energy consumption and high-carbon emission industry. Carbon emissions per ton of aluminum electrolysis exceed 15 tons, which is 6 times that of steel per ton. At present, China's aluminum electrolysis industry's electricity consumption accounts for more than 6% of the total social electricity consumption, and its carbon emissions account for about 4.5% of China's total carbon emissions.

[0003] Aluminum and aluminum alloys have strong corrosion resistance and wear resistance, with extremely low loss during use and basic properties will not be lost after repeated use. They have extremely high recycling value, and the energy consumption and carbon emissions of scrap aluminum recycling are only 3-5% of the original aluminum production. Therefore, scrap aluminum recycling is also regarded as the most promising way to save energy and reduce carbon emissions. Remelting is currently the main method for recycling scrap aluminum, but the alloy elements in scrap aluminum cannot be removed during the recycling process, and it can only be downgraded by mixing with pure aluminum. At present, my country has set a ceiling of 45 million tons of electrolytic aluminum production capacity, and the production capacity and output of raw aluminum are both saturated. At the same time, the lightweighting of automobiles has led to a surge in aluminum demand, and the clean energy represented by photovoltaics and wind power and the large-scale use of low-altitude aircraft have greatly boosted aluminum consumption. If scrap aluminum is recycled by mixing with pure aluminum and remelting, it will cause an imbalance in the supply and demand of electrolytic aluminum in my country, and it is estimated that there will be a supply and demand gap of up to 4.02 million tons in 2025. Therefore, developing new scrap aluminum recycling technologies to separate aluminum from other elements in scrap aluminum so that the recycled aluminum can reach or even exceed the quality level of original aluminum is the main development direction of scrap aluminum recycling in the future.

[0004] The three-layer molten salt electrolysis method is a method of purifying aluminum that has been applied industrially. This method uses liquid aluminum-copper alloy as the anode and liquid pure aluminum as the cathode, with a molten electrolyte between the two. It has the characteristics of high purity and high production efficiency. However, due to the vertical distribution structure of the anode and cathode of this method, it has a large pole distance, high energy consumption, and cannot remove silicon elements with similar density to aluminum. Summary of the invention

[0005] The purpose of the present invention is to provide an electrolytic cell for recycling pure aluminum from scrap aluminum and a method for using the same, so as to solve the problems of the vertical distribution structure of the anode and cathode in the existing three-layer molten salt electrolysis method, the large inter-electrode distance, the high energy consumption, and the inability to remove the silicon element.

[0006] The technical solution of the present invention is:

[0007] An electrolytic cell for recycling pure aluminum from scrap aluminum, the electrolytic cell comprising: a scrap aluminum inlet cover plate, a scrap aluminum anode, a porous ceramic plate, a pure aluminum inlet and outlet cover plates, an electrolyte, an electrolytic cell cover plate, an electrolytic cell shell, a pure aluminum cathode, an electrolytic cell insulation layer, an electrolytic cell insulation layer, a cathode guide rod, a cathode graphite block, an insulating partition, an anode graphite block, and an anode guide rod. The specific structure is as follows:

[0008] The inner side of the outer shell of the electrolytic cell with an open top is sequentially provided with an electrolytic cell insulation layer and an electrolytic cell insulation layer of matching shapes to form an electrolytic cell cavity. The electrolytic cell outer shell, the electrolytic cell insulation layer and the electrolytic cell insulation layer are closely attached to each other and an electrolytic cell cover plate is arranged on the top. A porous ceramic plate and an insulating partition are vertically arranged up and down in the middle of the inner cavity of the electrolytic cell, so that the inner cavity of the electrolytic cell is divided into an anode chamber and a cathode chamber. The anode chamber is sequentially stacked with anode graphite blocks and waste aluminum anodes from bottom to top, and the cathode chamber is sequentially stacked with cathode graphite blocks and pure aluminum from bottom to top. The aluminum cathode, electrolyte, cathode guide rod and anode guide rod are respectively horizontally penetrated through the side walls of the electrolytic cell shell, the electrolytic cell insulation layer and the electrolytic cell insulating layer. One end of the cathode guide rod is connected to the cathode graphite block, and one end of the anode guide rod is connected to the anode graphite block. The electrolytic cell cover plate is provided with a scrap aluminum inlet corresponding to the anode chamber, a pure aluminum inlet and outlet corresponding to the cathode chamber, a scrap aluminum inlet cover plate is provided at the scrap aluminum inlet, and a pure aluminum inlet and outlet cover plates are provided at the pure aluminum inlet and outlet.

[0009] The electrolytic cell for recycling pure aluminum from scrap aluminum has an overall shape of a cylindrical structure, a cubic structure or a rectangular parallelepiped structure.

[0010] The electrolytic cell for recycling pure aluminum from scrap aluminum has an outer shell of a steel plate with a thickness of 5 to 10 mm, an electrolytic cell insulation layer close to the inside of the electrolytic cell shell, and is built with one or more of mullite bricks, clay bricks, alumina bricks, fused magnesia bricks, magnesia-alumina spinel bricks and calcium silicate boards with a thickness of 10 to 20 cm, and a magnesia or corundum electrolytic cell insulation layer with a thickness of 5 to 10 cm is close to the inside of the electrolytic cell insulation layer.

[0011] The electrolytic cell for recycling pure aluminum from scrap aluminum has a top that is sealed by an electrolytic cell cover plate with a thickness of 10 to 20 cm, and the electrolytic cell cover plate is composed of an upper steel plate and a lower insulation material, and the insulation material is alumina, mullite, calcium silicate or clay; when no scrap aluminum is added or pure aluminum is not produced, the scrap aluminum inlet cover plate and the pure aluminum inlet and outlet cover plates are all in a closed state, ensuring that the inner cavity of the electrolytic cell is in a closed state; when scrap aluminum needs to be added or aluminum needs to be produced, the scrap aluminum inlet cover plate and the pure aluminum inlet and outlet cover plates are opened for operation.

[0012] The electrolytic cell for recycling pure aluminum from scrap aluminum has an insulating partition built integrally at the bottom of the insulating layer of the electrolytic cell. The insulating partition has a height of 50 to 100 cm and is made of magnesia, magnesia-aluminum spinel or corundum. A porous ceramic plate with a height of 20 to 50 cm is installed on the top of the insulating partition. The porous ceramic plate is made of alumina, magnesia-aluminum spinel or magnesia, and the holes in the porous ceramic plate are interconnected open pores.

[0013] In the electrolytic cell for recycling pure aluminum from scrap aluminum, the cathode guide rod and the anode guide rod are both made of iron or copper materials, and are connected to the cathode graphite block and the anode graphite block respectively by threads or casting. After assembly, the cathode guide rod and the anode guide rod are sealed at their entrances respectively.

[0014] The electrolytic cell for recycling pure aluminum from scrap aluminum has an anode graphite block height of 20 to 80 cm, a liquid scrap aluminum anode height of 10 to 80 cm, a bottom surface height of the liquid scrap aluminum anode lower than the upper edge height of the insulating partition, and an upper surface height of the liquid scrap aluminum anode lower than the upper edge height of the porous ceramic plate.

[0015] The electrolytic cell for recycling pure aluminum from scrap aluminum has a cathode graphite block height of 10 to 50 cm, and the upper surface of the cathode graphite block is lower than the upper edge of the insulating partition; the liquid pure aluminum cathode height is 5 to 50 cm, and the liquid level is kept lower than or flush with the lower edge of the porous ceramic plate; the molten electrolyte height is 10 to 40 cm, and the upper surface height of the molten electrolyte is lower than the upper edge height of the porous ceramic plate; the porous ceramic plate connects the molten electrolyte with the scrap aluminum anode, and the molten electrolyte is connected to the scrap aluminum anode through the porous ceramic plate.

[0016] The method for using the electrolytic cell for recycling pure aluminum from waste aluminum is as follows:

[0017] After the electrolytic cell is built, the electrolytic cell is first roasted by gas or resistance heating to discharge the water in the electrolytic cell. During the roasting process, the temperature of the inner cavity of the electrolytic cell is heated to 670-750°C by gas or resistance. At this time, molten scrap aluminum and pure aluminum at 670-750°C are poured into the anode chamber and cathode chamber respectively, and then molten electrolyte at 670-750°C is poured into the cathode chamber. The heating device is withdrawn and the electrolytic cell is powered on for normal electrolysis.

[0018] The electrolysis in the electrolytic cell adopts direct current. After power is turned on, the current enters the liquid scrap aluminum anode through the anode graphite block via the anode guide rod, and then enters the liquid pure aluminum cathode through the molten electrolyte immersed in the scrap aluminum anode, the porous ceramic plate and the molten electrolyte in the cathode chamber in sequence, and finally is discharged through the cathode graphite block and the cathode guide rod; during the electrolysis process, the aluminum in the scrap aluminum anode undergoes electrochemical dissolution and enters the molten electrolyte in the form of aluminum ions, and then moves through the molten electrolyte to the liquid pure aluminum cathode for precipitation.

[0019] The method for using the electrolytic cell for recycling pure aluminum from waste aluminum is as follows: during the electrolysis process, the cathode current density is 0.4-1.2A / cm 2 In order to keep the pure aluminum cathode liquid level below or flush with the bottom edge of the porous ceramic plate, pure aluminum is taken out from the cathode chamber through a vacuum ladle every 8 to 48 hours; the anode current density is 0.4 to 1.2 A / cm 2 In order to ensure that the liquid level of the scrap aluminum anode is higher than the bottom edge of the porous ceramic plate, molten scrap aluminum is added to the anode chamber every 4 to 24 hours.

[0020] The design idea of ​​the present invention is:

[0021] The present invention uses waste aluminum as the anode, pure aluminum as the cathode, and high-temperature molten salt as the electrolyte. During the electrolysis process, metals with electrode potentials more positive than aluminum in the waste aluminum alloy (such as Si, Fe, Ti, etc.) do not dissolve and remain in the anode, and metals with electrode potentials more negative than aluminum (such as Ca, Mg, etc.) dissolve into the electrolyte together with aluminum, but the ions formed by them have a more negative potential than aluminum ions, and do not deposit at the cathode but remain in the electrolyte, thereby realizing the leapfrogging recovery of waste aluminum. However, if the ordinary electrolytic cell structure is used for recovery, that is, the pure aluminum cathode, the molten electrolyte and the waste aluminum anode are vertically distributed from top to bottom due to different densities, the excessive distance between the pure aluminum cathode and the waste aluminum anode will cause the recovery process to have a large energy consumption. In addition, the density of silicon element is similar to that of aluminum element, and it is difficult to remove. In view of the above problems, the present invention uses a porous ceramic plate to divide the electrolytic cell into a cathode chamber and an anode chamber. During the recovery process, the molten waste aluminum does not immerse in the porous ceramic plate due to the strong surface tension, and the molten electrolyte immerses in the porous ceramic plate to connect the waste aluminum anode and the pure aluminum cathode. The electrolytic cell structure of the present invention thus has a smaller distance between the cathode and anode, thereby having lower energy consumption. In addition, the horizontally distributed structure can also solve the problem that silicon cannot be removed due to its similar density to aluminum.

[0022] The advantages and beneficial effects of the present invention are:

[0023] The electrolytic cell of the present invention is used to recycle scrap aluminum in a leapfrog manner. The scrap aluminum anode is in liquid state, and the pure aluminum regenerated at the cathode is also in liquid state. The current efficiency and production efficiency are high during the electrolysis process. The purity of the pure aluminum recovered in the cathode chamber can reach more than 99.70%, reaching or even exceeding the quality level of original aluminum. Moreover, since the electrolytic cell of the present invention shortens the distance between the cathode and the anode, and reduces the cell resistance and cell voltage, the energy consumption of the entire electrolytic recovery of scrap aluminum is about 4 to 8 kW·h / (kg Al), which is equivalent to 30 to 50% of the original aluminum production, and has good industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a structural diagram of an electrolytic cell for recycling pure aluminum from scrap aluminum.

[0025] Names of the reference numerals in the figure: 1-cover plate for waste aluminum inlet, 2-waste aluminum anode, 3-porous ceramic plate, 4-cover plate for pure aluminum inlet and outlet, 5-electrolyte, 6-electrolytic cell cover plate, 7-electrolytic cell shell, 8-pure aluminum cathode, 9-electrolytic cell insulation layer, 10-electrolytic cell insulation layer, 11-cathode guide rod, 12-cathode graphite block, 13-insulating partition, 14-anode graphite block, 15-anode guide rod, 16-anode chamber, 17-cathode chamber. DETAILED DESCRIPTION

[0026] like Figure 1 As shown, the present invention proposes an electrolytic cell for recycling pure aluminum from scrap aluminum, which mainly includes: a scrap aluminum inlet cover plate 1, a scrap aluminum anode 2, a porous ceramic plate 3, a pure aluminum inlet and outlet cover plate 4, an electrolyte 5, an electrolytic cell cover plate 6, an electrolytic cell shell 7, a pure aluminum cathode 8, an electrolytic cell insulation layer 9, an electrolytic cell insulation layer 10, a cathode guide rod 11, a cathode graphite block 12, an insulating partition 13, an anode graphite block 14, an anode guide rod 15, etc. The specific structure is as follows:

[0027] An electrolytic cell heat preservation layer 9 and an electrolytic cell insulating layer 10 of matching shapes are sequentially arranged on the inner side of an electrolytic cell shell 7 with an open top to form an electrolytic cell cavity. The electrolytic cell shell 7, the electrolytic cell heat preservation layer 9 and the electrolytic cell insulating layer 10 are closely attached to each other and an electrolytic cell cover plate 6 is arranged on the top. A porous ceramic plate 3 and an insulating partition 13 are vertically arranged in the middle of the electrolytic cell cavity, so that the electrolytic cell cavity is divided into an anode chamber 16 and a cathode chamber 17. The anode chamber 16 is sequentially stacked with an anode graphite block 14 and a waste aluminum anode 2 from bottom to top, and the cathode chamber 17 is sequentially stacked with a cathode graphite block 12, a pure aluminum cathode 8 and an electrolyte 5 from bottom to top. A cathode guide rod 11 and an anode guide rod 15 are respectively horizontally penetrated through the side walls of the electrolytic cell shell 7, the electrolytic cell heat preservation layer 9 and the electrolytic cell insulating layer 10, one end of the cathode guide rod 11 is connected to the cathode graphite block 12, and one end of the anode guide rod 15 is connected to the anode graphite block 14. The electrolytic cell cover 6 is provided with a scrap aluminum inlet corresponding to the anode chamber 16 and a pure aluminum inlet and outlet corresponding to the cathode chamber 17. The scrap aluminum inlet is provided with a scrap aluminum inlet cover 1, and the pure aluminum inlet and outlet are provided with a pure aluminum inlet and outlet cover 4.

[0028] The electrolytic cell of the present invention can be a cylindrical structure, a cubic structure or a rectangular parallelepiped structure. The inner cavity of the electrolytic cell is divided into a cathode chamber 17 and an anode chamber 16 by a porous ceramic plate 3 and an insulating partition 13. The electrolytic cell shell 7 is a steel plate with a thickness of 5 to 10 mm. The electrolytic cell insulation layer 9 is close to the inside of the electrolytic cell shell 7 and is built by one or more of mullite bricks, clay bricks, alumina bricks, fused magnesia bricks, magnesia-alumina spinel bricks and calcium silicate boards with a thickness of 10 to 20 cm. The top of the electrolytic cell is sealed by an electrolytic cell cover plate 6 with a thickness of 10 to 20 cm. The electrolytic cell cover plate 6 is composed of an upper steel plate and a lower insulation material. The insulation material is alumina, mullite, calcium silicate or clay. The main function of the electrolytic cell cover plate 6 is sealing and heat preservation, reducing the volatilization loss of molten salt in the electrolytic cell and blocking the heat loss of the electrolytic cell. The scrap aluminum inlet cover plate 1 and the pure aluminum inlet and outlet cover plate 4 are arranged on the electrolytic cell cover plate 6. When scrap aluminum is not added or pure aluminum is not discharged, the two cover plates are in a closed state to ensure that the inner cavity of the electrolytic cell is in a sealed state. When scrap aluminum needs to be added or aluminum needs to be discharged, the scrap aluminum inlet cover plate 1 and the pure aluminum inlet and outlet cover plate 4 can be opened for operation.

[0029] A magnesia or corundum electrolytic cell insulating layer 10 with a thickness of 5 to 10 cm is closely attached to the inside of the electrolytic cell insulation layer 9. An insulating partition 13 is integrally built at the bottom of the electrolytic cell insulating layer 10. The insulating partition 13 has a height of 50 to 100 cm, and the inner cavity of the electrolytic cell is divided into a cathode chamber 17 and an anode chamber 16. The insulating partition 13 is made of magnesia, magnesia-aluminum spinel or corundum. A porous ceramic plate 3 with a height of 20 to 50 cm is installed on the top of the insulating partition 13. The porous ceramic plate 3 can be alumina, magnesia-aluminum spinel or magnesia. The holes in the porous ceramic plate 3 are connected open pores with a pore size of 150 to 400 μm and a porosity of more than 60%.

[0030] The anode chamber 16 is provided with an anode graphite block 14, an anode guide rod 15, and a liquid waste aluminum anode 2. The cathode guide rod 11 and the anode guide rod 15 are made of iron or copper materials, and are connected to the cathode graphite block 12 and the anode graphite block 14 respectively by screw thread or casting. After assembly, the entrances of the cathode guide rod 11 and the anode guide rod 15 are sealed respectively. The height of the anode graphite block 14 is 20 to 80 cm, and the height of the liquid waste aluminum anode 2 is 10 to 80 cm. The bottom surface height of the liquid waste aluminum anode 2 is lower than the upper edge height of the insulating partition 13, and the upper surface height of the liquid waste aluminum anode 2 is lower than the upper edge height of the porous ceramic plate 3.

[0031] The cathode chamber 17 is provided with a cathode graphite block 12, a cathode guide rod 11, a liquid pure aluminum cathode 8 and a molten electrolyte 5. The height of the cathode graphite block 12 is 10 to 50 cm, and the upper surface of the cathode graphite block 12 is lower than the upper edge of the insulating partition 13 to prevent contact with the waste aluminum anode 2. The height of the liquid pure aluminum cathode 8 is 5 to 50 cm, and the liquid level is kept slightly lower than the lower edge of the porous ceramic plate 3 (or flush with the lower edge of the porous ceramic plate 3) so that the pure aluminum cathode 8 does not contact the porous ceramic plate 3. The height of the molten electrolyte 5 is 10 to 40 cm, and the upper surface height of the molten electrolyte 5 is lower than the upper edge height of the porous ceramic plate 3. The porous ceramic plate 3 plays the role of connecting the molten electrolyte 5 with the waste aluminum anode 2. The waste aluminum anode 2 has a high surface tension and will not be immersed in the porous ceramic plate 3 when in contact with it. The molten electrolyte 5 contacts the waste aluminum anode 2 through the porous ceramic plate 3 to achieve the purpose of connection.

[0032] The molten salt electrolyte used for electrolysis is an alkali metal chloride molten salt system based on NaCl-KCl, and chlorides such as CaCl2, MgCl2 and LiCl may also be added. The mass percentage of each substance in the electrolyte is NaCl 20-50%, KCl 20-50%, CaCl2 0-20%, MgCl2 0-20%, LiCl 0-20%. In addition, a certain amount of aluminum-containing electrolyte, such as AlF3, Na3AlF6 and AlCl3, etc., needs to be added to the electrolyte, and the addition amount is 0-20%. In this embodiment, the mass percentage of each substance in the electrolyte is: NaCl 38.9%, KCl 49.5%, Na3AlF611.6%.

[0033] like Figure 1 As shown, the present invention provides a method for using an electrolytic cell for recycling pure aluminum from waste aluminum as follows:

[0034] After the electrolytic cell is built, it is first roasted by gas or resistance heating to discharge the moisture in the electrolytic cell. During the roasting process, the temperature of the inner cavity of the electrolytic cell is heated to 670-750°C by gas or resistance. At this time, molten scrap aluminum and pure aluminum at 670-750°C are poured into the anode chamber 16 and the cathode chamber 17 respectively, and then molten electrolyte 5 at 670-750°C is poured into the cathode chamber 17. The heating device is withdrawn and the electrolytic cell is powered on for normal electrolysis.

[0035] The electrolysis of the electrolytic cell adopts direct current. After power is turned on, the current enters the liquid waste aluminum anode 2 through the anode graphite block 14 through the anode guide rod 15, and then enters the liquid pure aluminum cathode 8 through the molten electrolyte 5 immersed in the porous ceramic plate 3, and finally is led out through the cathode graphite block 12 and the cathode guide rod 11. During the electrolysis process, the aluminum in the waste aluminum anode 2 undergoes electrochemical dissolution and enters the molten electrolyte in the form of aluminum ions, and then moves through the molten electrolyte to the liquid pure aluminum cathode for precipitation. During the electrolysis process, the cathode current density is 0.4~1.2A / cm 2 In order to keep the pure aluminum cathode 8 liquid level below the bottom edge of the porous ceramic plate 3, pure aluminum is taken out from the cathode chamber 17 by vacuum lifting every 8 to 48 hours. The anode current density is 0.4 to 1.2 A / cm 2 In order to ensure that the liquid level of the scrap aluminum anode 2 is higher than the lower edge of the porous ceramic plate 3, molten scrap aluminum is added to the anode chamber 16 once every 4 to 24 hours.

[0036] The electrolytic cell of the present invention is a self-heating structure. The thermal balance of the electrolytic cell can be maintained by the resistance of molten pure aluminum, molten scrap aluminum, molten electrolyte, anode graphite block and cathode graphite block. When the self-heating of the electrolytic cell is insufficient, an auxiliary electrode can be inserted from the side or top of the molten electrolyte of the electrolytic cell for heating to ensure that the electrolysis temperature of the electrolytic cell is between 670 and 750°C.

[0037] The scrap aluminum anode used in the present invention includes not only recycled scrap aluminum, new scrap aluminum produced in the production process, but also aluminum alloys that have reached the end of their service life and alloys with an aluminum mass percentage greater than 30% produced by other industries. The pure aluminum cathode is raw aluminum with a purity of more than 99.70wt%.

Claims

1. An electrolytic cell for recycling pure aluminum from waste aluminum, characterized in that: The electrolytic cell comprises: a waste aluminum inlet cover plate, a waste aluminum anode, a porous ceramic plate, a pure aluminum inlet and outlet cover plates, an electrolyte, an electrolytic cell cover plate, an electrolytic cell shell, a pure aluminum cathode, an electrolytic cell insulation layer, an electrolytic cell insulation layer, a cathode guide rod, a cathode graphite block, an insulating partition, an anode graphite block, and an anode guide rod. The specific structure is as follows: The inner side of the outer shell of the electrolytic cell with an open top is sequentially provided with an electrolytic cell insulation layer and an electrolytic cell insulation layer of matching shapes to form an electrolytic cell cavity. The electrolytic cell outer shell, the electrolytic cell insulation layer and the electrolytic cell insulation layer are closely attached to each other and an electrolytic cell cover plate is arranged on the top. A porous ceramic plate and an insulating partition are vertically arranged up and down in the middle of the inner cavity of the electrolytic cell, so that the inner cavity of the electrolytic cell is divided into an anode chamber and a cathode chamber. The anode chamber is sequentially stacked with anode graphite blocks and waste aluminum anodes from bottom to top, and the cathode chamber is sequentially stacked with cathode graphite blocks and pure aluminum from bottom to top. The aluminum cathode, electrolyte, cathode guide rod and anode guide rod are respectively horizontally penetrated through the side walls of the electrolytic cell shell, the electrolytic cell insulation layer and the electrolytic cell insulating layer. One end of the cathode guide rod is connected to the cathode graphite block, and one end of the anode guide rod is connected to the anode graphite block. The electrolytic cell cover plate is provided with a scrap aluminum inlet corresponding to the anode chamber, a pure aluminum inlet and outlet corresponding to the cathode chamber, a scrap aluminum inlet cover plate is provided at the scrap aluminum inlet, and a pure aluminum inlet and outlet cover plates are provided at the pure aluminum inlet and outlet.

2. The electrolytic cell for recovering pure aluminum from waste aluminum according to claim 1, characterized in that: The overall shape of the electrolytic cell is a cylindrical structure, a cubic structure or a rectangular parallelepiped structure.

3. The electrolytic cell for recovering pure aluminum from waste aluminum according to claim 1, characterized in that: The outer shell of the electrolytic cell is a steel plate with a thickness of 5 to 10 mm. The electrolytic cell insulation layer is close to the inner shell of the electrolytic cell and is built with one or more of the following materials: mullite bricks, clay bricks, alumina bricks, fused magnesia bricks, magnesia-alumina spinel bricks and calcium silicate boards with a thickness of 10 to 20 cm. The inner insulation layer of the electrolytic cell is a magnesia or corundum electrolytic cell insulation layer with a thickness of 5 to 10 cm.

4. The electrolytic cell for recovering pure aluminum from waste aluminum according to claim 1, characterized in that: The top of the electrolytic cell is sealed by an electrolytic cell cover with a thickness of 10 to 20 cm. The electrolytic cell cover is composed of an upper steel plate and a lower insulation material. The insulation material is alumina, mullite, calcium silicate or clay. When no scrap aluminum is added or pure aluminum is not produced, the scrap aluminum inlet cover and the pure aluminum inlet and outlet cover are all in a closed state to ensure that the inner cavity of the electrolytic cell is in a closed state. When scrap aluminum needs to be added or aluminum needs to be produced, the scrap aluminum inlet cover and the pure aluminum inlet and outlet cover are opened for operation.

5. The electrolytic cell for recovering pure aluminum from scrap aluminum according to claim 1, characterized in that: An insulating partition is integrally built at the bottom of the insulating layer of the electrolytic cell. The height of the insulating partition is 50 to 100 cm. The material of the insulating partition is magnesia sand, magnesia aluminum spinel or corundum. A porous ceramic plate with a height of 20 to 50 cm is installed on the top of the insulating partition. The porous ceramic plate is made of alumina, magnesia aluminum spinel or magnesia. The holes in the porous ceramic plate are connected open pores.

6. The electrolytic cell for recovering pure aluminum from scrap aluminum according to claim 1, characterized in that: The cathode guide rod and the anode guide rod are both made of iron or copper materials, and are connected to the cathode graphite block and the anode graphite block respectively by means of threads or casting. After assembly, the entrances of the cathode guide rod and the anode guide rod are sealed respectively.

7. The electrolytic cell for recovering pure aluminum from scrap aluminum according to claim 1, characterized in that: The height of the anode graphite block is 20-80 cm, the height of the liquid waste aluminum anode is 10-80 cm, the bottom height of the liquid waste aluminum anode is lower than the upper edge height of the insulating partition, and the upper surface height of the liquid waste aluminum anode is lower than the upper edge height of the porous ceramic plate.

8. The electrolytic cell for recovering pure aluminum from scrap aluminum according to claim 1, characterized in that: The height of the cathode graphite block is 10 to 50 cm, and the upper surface of the cathode graphite block is lower than the upper edge of the insulating partition; the height of the liquid pure aluminum cathode is 5 to 50 cm, and the liquid level is kept lower than or flush with the lower edge of the porous ceramic plate; the height of the molten electrolyte is 10 to 40 cm, and the upper surface height of the molten electrolyte is lower than the upper edge height of the porous ceramic plate; the porous ceramic plate connects the molten electrolyte with the waste aluminum anode, and the molten electrolyte is connected to the waste aluminum anode through the porous ceramic plate.

9. A method for using the electrolytic cell for recovering pure aluminum from waste aluminum as claimed in any one of claims 1 to 8, characterized in that: The specific process is as follows: After the electrolytic cell is built, the electrolytic cell is first roasted by gas or resistance heating to discharge the water in the electrolytic cell. During the roasting process, the temperature of the inner cavity of the electrolytic cell is heated to 670-750°C by gas or resistance. At this time, molten scrap aluminum and pure aluminum at 670-750°C are poured into the anode chamber and cathode chamber respectively, and then molten electrolyte at 670-750°C is poured into the cathode chamber. The heating device is withdrawn and the electrolytic cell is powered on for normal electrolysis. The electrolysis in the electrolytic cell adopts direct current. After power is turned on, the current enters the liquid scrap aluminum anode through the anode graphite block via the anode guide rod, and then enters the liquid pure aluminum cathode through the molten electrolyte immersed in the scrap aluminum anode, the porous ceramic plate and the molten electrolyte in the cathode chamber in sequence, and finally is discharged through the cathode graphite block and the cathode guide rod; during the electrolysis process, the aluminum in the scrap aluminum anode undergoes electrochemical dissolution and enters the molten electrolyte in the form of aluminum ions, and then moves through the molten electrolyte to the liquid pure aluminum cathode for precipitation.

10. The method for using the electrolytic cell for recovering pure aluminum from waste aluminum according to claim 9, characterized in that: During the electrolysis process, the cathode current density is 0.4~1.2A / cm 2 In order to keep the pure aluminum cathode liquid level below or flush with the bottom edge of the porous ceramic plate, pure aluminum is taken out from the cathode chamber through a vacuum ladle every 8 to 48 hours; the anode current density is 0.4 to 1.2 A / cm 2 In order to ensure that the liquid level of the scrap aluminum anode is higher than the bottom edge of the porous ceramic plate, molten scrap aluminum is added to the anode chamber every 4 to 24 hours.

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