Method for producing metallic aluminum and polysilicon from high-silicon aluminum-containing resources

Abstract

The present application belongs to the technical field of aluminum metallurgy, and particularly relates to a method for producing metallic aluminum and polysilicon by using high-silicon aluminum-containing resources. First, an aluminum-silicon oxidized material is obtained by pretreatment of high-silicon aluminum-containing resource raw materials, and then metallic aluminum and copper-aluminum-silicon alloy enriched with silicon are produced by molten salt electrolysis in a double-chamber electrolytic cell. The copper-aluminum-silicon alloy is electrolyzed in a single-chamber electrolytic cell to produce aluminum-silicon alloy and / or polysilicon, and the aluminum-silicon alloy is further separated by a physical method to obtain polysilicon. The present application has the characteristics of low production cost, continuous electrolysis operation, high product quality, clean environment, etc.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of aluminum metallurgy, and particularly relates to a method for producing metallic aluminum and polysilicon by using high-silicon aluminum-containing resources. BACKGROUND

[0002] Aluminum is an important light metal and is widely used in transportation, appliances, packaging, building materials, and electric wires. In 2020, the production of primary aluminum (electrolytic aluminum) in China was 37.08 million tons, ranking first among all non-ferrous metals.

[0003] The existing method for producing metallic aluminum is the traditional Hall-Heroult molten salt electrolysis process. The electrolysis equipment is mainly a pre-baked anode electrolytic cell composed of a carbon anode, a cryolite molten salt electrolyte, and a carbon cathode. Metallurgical grade alumina is used as the raw material, and primary aluminum is obtained by electrolysis at 900-960℃. At the same time, the carbon anode is continuously consumed and produces gas mainly composed of CO2. Although this method has been widely used, it has many problems: ① The electrolysis energy consumption is high, with an electricity consumption of about 13,000 kW·h per ton of aluminum, and the electricity energy efficiency is only about 50%; ② The consumption of carbon anodes is large, and the replacement operation affects the production efficiency, and the mixed gas containing CO2 and CO, SO2, and carbon fluorides pollutes the environment; ③ It does not have the function of impurity removal or refining. During the electrolysis process, the oxides of elements with more positive electricity than aluminum (such as Fe2O3, SiO2, TiO2, etc.) will be precipitated at the cathode at the same time as Al, causing the quality of the primary aluminum product to be impure and the grade to decrease. In order to ensure the quality of the primary aluminum product, the industry standard YS / T 803-2012 requires that the chemical composition of metallurgical grade alumina be: Al2O3≥98.4wt%, SiO2≤0.06wt%, Fe2O3≤0.03wt%, and in addition, the physical properties such as specific surface area and particle size distribution are also required.

[0004] In order to meet the product requirements of metallurgical grade alumina and maximize production profits, the alumina industry currently often uses bauxite with alumina hydrate (Al2O3·nH2O, n=1 or 3) as the main mineral component as the production raw material, and adopts the Bayer process, sintering process, or combined process for decomposing the bauxite. In addition, the crude sodium aluminate leaching solution also needs to undergo a deep desiliconization process to prevent the SiO2 impurity content in the alumina product from exceeding the standard.

[0005] In addition, a large amount of coal gangue and fly ash solid waste is generated in the domestic coal mining and coal-fired power generation industry, and the production of fly ash in 2019 was as high as 748 million tons, and the accumulated coal gangue was more than 8 billion tons, and the Al2O3 content in high-aluminum fly ash and high-aluminum coal gangue can be as high as 40-55%, if the Al2O3 therein can be extracted, it will have double benefits of resource utilization and environmental protection, but due to the dual pressure of low aluminum-silicon ratio in raw materials and high quality requirements of product alumina, the technology for extracting Al2O3 from fly ash or coal gangue still faces the challenge of high production cost.

[0006] Moreover, in the process of extracting alumina from aluminum-containing resources, the associated SiO2 is mostly in the form of red mud as solid waste and is stored in the slag field, which has the problems of environmental pollution risk and resource waste. Especially, the SiO2 content in high-silicon bauxite, fly ash, coal gangue and other aluminum-containing resources is relatively high. If the Al2O3 or SiO2 therein can be used to produce metallic aluminum and polysilicon, it will have multiple significance.

[0007] In summary, for the alumina industry, high-quality aluminum ore resources are becoming exhausted, and the desiliconization and iron removal pressure is large, and the associated SiO2 cannot be effectively utilized; for the electrolytic aluminum industry, the current electrolysis method generally strictly requires that the alumina is completely dissolved in the electrolyte, and these methods also have the disadvantages of high quality requirement for alumina raw materials, difficult to guarantee the purity of metallic aluminum product, limited selection of electrolyte, long production process, complex and poor adaptability of electrolysis operation. SUMMARY

[0008] The purpose of the present application is to provide a method for producing metallic aluminum and polysilicon using high-silicon aluminum-containing resources, breaking the barriers between the alumina industry and the electrolytic aluminum industry, and utilizing the aluminum elements in high-silicon aluminum-containing resources to produce metallic aluminum while utilizing the silicon elements to produce polysilicon.

[0009] According to the method for producing metallic aluminum and polysilicon using high-silicon aluminum-containing resources according to the specific embodiment of the present application, the method comprises the following steps:

[0010] Step (1): obtaining aluminum-silicon oxide material from high-silicon aluminum-containing resources through a pretreatment process;

[0011] Step (2): using the aluminum-silicon oxide material as electrolysis raw material, preparing metallic aluminum and copper-aluminum-silicon alloy in a double-chamber electrolytic cell by a molten salt electrolysis method;

[0012] Step (3): taking out the copper-aluminum-silicon alloy and placing it in a single-chamber electrolytic cell, preparing aluminum-silicon alloy or / and polysilicon by a molten salt electrolysis method.

[0013] According to the method for producing metal aluminum and polysilicon by using high-silicon aluminum-containing resources according to the specific embodiment of the present application, in step (1), the mass ratio of Al2O3 / SiO2 in the high-silicon aluminum-containing resources is 1:(0.5-7), and the high-silicon aluminum-containing resources include one or more of high-silicon bauxite, fly ash, coal gangue, kaolin and alunite; the content of Al2O3 and SiO2 in the aluminum-silicon oxide material is greater than or equal to 90.0% by weight, and the content of Al2O3 is greater than or equal to 40.0% by weight, and the content of SiO2 is greater than or equal to 0.1% by weight.

[0014] According to the method for producing metal aluminum and polysilicon by using high-silicon aluminum-containing resources according to the specific embodiment of the present application, in step (1), the purpose of the pretreatment process is to increase the content of Al2O3+SiO2 in the silicon aluminum-containing resources and reduce the content of associated impurities such as Fe, Ti and Na. According to the properties of the treatment reagent, the pretreatment process can be divided into an alkali pretreatment process, an acid pretreatment process or an acid-alkali combined pretreatment process. The specific methods are various and difficult to enumerate one by one. Hereinafter, only a brief description is given.

[0015] The alkali pretreatment process includes: the high-silicon aluminum-containing resources (especially natural minerals such as bauxite) are subjected to a limestone sintering method, an alkali-lime sintering method, a pre-desiliconization-alkali-lime sintering method, a pre-desiliconization-caustic soda leaching method or the like to obtain a sodium aluminate alkaline leaching solution, and then the sodium aluminate alkaline leaching solution is subjected to a seed decomposition process and a calcination decomposition process to obtain an aluminum-silicon oxide material. The alkali pretreatment process has the characteristics that the alkaline leaching solution does not need to be subjected to a lime deep desiliconization treatment, the use of lime and the generation of desiliconization residues can be reduced, and part of the SiO2 is retained in the aluminum-silicon oxide material.

[0016] The acid pretreatment process includes: the high-silicon aluminum-containing resources are subjected to atmospheric leaching, pressurized leaching or roasting-leaching to obtain an aluminum-containing acid leaching solution, and then the aluminum salt (aluminum chloride, aluminum sulfate or aluminum nitrate) is precipitated from the leaching solution by concentration and crystallization, and then the aluminum oxide material is obtained by calcination, and the aluminum-silicon oxide material is obtained by mixing the aluminum oxide material with some acid leaching residues (mainly SiO2). The acid pretreatment process has the characteristics that the acid leaching solution does not need to be subjected to a deep iron removal / calcium removal treatment, and the use of ion exchange resins with low production efficiency can be avoided.

[0017] For high-silicon aluminum-containing resources with high content of Al2O3+SiO2, such as fly ash, the pretreatment step can be omitted, or the high-silicon aluminum-containing resources can be subjected to simple alkali washing / acid washing to remove impurities and then sent to the double-chamber electrolytic cell as the aluminum-silicon oxide material.

[0018] According to the method for producing metal aluminum and polysilicon by using high-silicon aluminum-containing resources according to the specific embodiment of the present application, in step (2), the double-chamber electrolytic cell is divided into an anode chamber and a cathode chamber to physically separate the anode electrolyte from the cathode electrolyte, the anode chamber is provided with an anode, the cathode chamber is provided with a cathode, the bottom of the double-chamber electrolytic cell also contains copper-aluminum alloy, and the copper-aluminum alloy is in contact with the anode electrolyte and the cathode electrolyte, respectively; under the condition of power supply operation, aluminum-silicon oxidized material is fed into the anode chamber, metal aluminum is obtained in the cathode chamber, and the copper-aluminum alloy at the bottom of the double-chamber electrolytic cell is converted into copper-aluminum-silicon alloy.

[0019] The reaction principle in the double-chamber electrolytic cell can be summarized as follows: in the anode chamber, aluminum-silicon oxidized material is added into the anode electrolyte, oxidation reaction occurs on the anode and gas is generated, and aluminum ions (in dissolved and / or undissolved states) and silicon ions (in dissolved and / or undissolved states) in the anode chamber are reduced into aluminum atoms and silicon atoms at the interface between the anode electrolyte and the copper-aluminum alloy and enter the liquid copper-aluminum alloy; in the cathode chamber, the aluminum atoms in the copper-aluminum alloy are discharged at the interface between the cathode electrolyte and the copper-aluminum alloy to form aluminum ions and enter the cathode electrolyte, the aluminum ions in the cathode electrolyte are reduced into aluminum atoms to form a liquid metal aluminum and float on the cathode electrolyte. With the continuous progress of the electrolysis process, the copper-aluminum alloy is gradually enriched with silicon and is converted into copper-aluminum-silicon alloy.

[0020] According to the method for producing metal aluminum and polysilicon by using high-silicon aluminum-containing resources according to the specific embodiment of the present application, in step (2), the Al content in the copper-aluminum alloy is 55-80 at%, and the copper-aluminum alloy does not contain or contains not more than 10 at% of Si (because crude copper and part of crude aluminum are melted into copper-aluminum alloy for recycling, both of which can contain a certain amount of silicon that is not completely removed, but in order to distinguish the copper-aluminum-silicon alloy enriched with silicon after electrolysis, it is still referred to as copper-aluminum alloy); the copper-aluminum alloy remains in a liquid state during normal electrolysis, and the density is greater than the density of the anode electrolyte or the cathode electrolyte.

[0021] According to the method for producing metal aluminum and polysilicon by using high-silicon aluminum-containing resources according to the specific embodiment of the present application, in step (2), the anode is a carbon anode or an inert anode; and the cathode is graphite, aluminum, TiB2 / C, or one or more combinations thereof.

[0022] The inert anode includes ceramic materials (such as SnO2 and doped SnO2, NiFe2O4, CaTiO3, CaRuO3, CaRu x Ti 1-xO3, ITO), metal materials (such as Cu-Al alloy, Ni-Fe alloy, Ni-Fe-Cu alloy), metal ceramic composite materials (such as Cu-NiFe2O4, Cu-NiO-NiFe2O4, Ni-NiO-NiFe2O4, Cu-Ni-NiO-NiFe2O4, Ni-CaRu x Ti 1-x O3).

[0023] According to the method for producing metal aluminum and polysilicon from high-silicon aluminum-containing resources according to the specific embodiment of the present application, in step (2), the anode current density of the double-chamber electrolytic cell when normally working is 0.1-1.5 A / cm 2 , and the temperature is 800-1000℃.

[0024] According to the method for producing metal aluminum and polysilicon from high-silicon aluminum-containing resources according to the specific embodiment of the present application, in step (2), the anode electrolyte is a fluoride system or a chloride system.

[0025] When the anode electrolyte is a fluoride system, the fluoride system comprises 60-90 wt% cryolite, 5-30 wt% AlF3, 1-5 wt% Al2O3, and an additive with a content of not more than 15 wt%; the cryolite is one or more of Na3AlF6, Li3AlF6, and K3AlF6, and the additive is one or more of LiF, NaF, KF, CaF2, MgF2, and BaF2.

[0026] According to the common knowledge in the art, the electrolyte containing 1:3 (molar ratio) of AlF3, MeF (Me = Li, Na, K) and Me3AlF6 (Me = Li, Na, K) is equivalent and replaceable. The above components and compositions are only one commonly used expression, and there are many other expressions, for example, the mass fraction can be converted into the corresponding molar fraction; the electrolyte is composed of AlF3, MeF (Me = Li, Na, K), Al2O3, and an additive by replacing the Me3AlF6 (Me = Li, Na, K) component with AlF3 and MeF (Me = Li, Na, K).

[0027] The fluoride system anode electrolyte contains cryolite (Me3AlF6, Me = Li, Na, K) component, and has a certain solubility for aluminum-silicon oxidation materials. The initial crystallization temperature of the electrolyte, the physical and chemical properties such as conductivity, etc. can be reduced and adjusted by adding AlF3 and other fluoride or chloride. When the aluminum oxide material is added to the fluoride system, the aluminum-silicon oxidation material undergoes a dissolution reaction and generates dissolved aluminum-containing ions and silicon-containing ions (for example, AlF4 - , SiF6 2- , etc.), which are respectively in the form of Al3+ and Si 4+ and oxygen-containing ions (e.g. AlOF5 4- , to O 2- ). Under the action of an electric field, the oxygen-containing ions in the anode chamber are oxidized on the anode and O2 or CO2+CO gas is generated, while the aluminum-containing ions and silicon-containing ions are reduced at the interface between the anode electrolyte and the copper-aluminum alloy to generate aluminum atoms and silicon atoms and enter the copper-aluminum alloy, with the reaction formula being:

[0028] Carbon anode: O 2- +1 / xC-2e - →1 / xCO x ↑ (x = 1 or 2)

[0029] Or inert anode: O 2- -2e - →0.5O2↑

[0030] Interface: Al 3+ +3e - →Al (copper-aluminum alloy)

[0031] Si 4+ +4e - →Si (copper-aluminum alloy)

[0032] The aluminum-silicon oxidation material at the interface between the liquid copper-aluminum alloy and the anode electrolyte can continue to dissolve in the anode electrolyte and replenish the aluminum-containing ions and silicon-containing ions consumed at the interface to reduce the concentration polarization and avoid the occurrence of side reactions, or directly undergo reduction reactions at the interface to ensure that the aluminum-containing ions or / and silicon-containing ions in the anode chamber are continuously reduced to aluminum atoms or / and silicon atoms and enter the liquid copper-aluminum alloy.

[0033] When the anode electrolyte is a fluoride system, the chloride system is CaCl2, or the chloride system is composed of CaCl2 and one or more of NaCl, KCl, BaCl2, CaF2, LiCl, and CaO.

[0034] The above-mentioned chloride system anode electrolyte has very low solubility for aluminum-silicon oxidation material, but has a certain solubility for O 2- . When aluminum-silicon oxidation material is added to the above-mentioned chloride system anode electrolyte, under the action of an electric field, the solid aluminum-silicon oxidation material directly undergoes reduction reactions at the interface between the anode electrolyte and the copper-aluminum alloy, in which the aluminum ions and silicon ions are reduced to aluminum atoms and silicon atoms, respectively, and enter the liquid copper-aluminum alloy, and the dissociated O 2- dissolves in the anode electrolyte and migrates to the anode, and then undergoes oxidation reactions on the surface of the anode. The reaction formula is:

[0035] Interface: Al2O3+ 6e - → 2Al (copper-aluminum alloy) + 3O 2-

[0036] SiO2+ 4e - → Si (copper-aluminum alloy) + 2O 2-

[0037] Carbon anode: O 2- + 1 / x C - 2e - → 1 / x CO x ↑ (x = 1 or 2)

[0038] Or inert anode: O 2- - 2e - → 0.5O2↑

[0039] Further, to adjust the physical and chemical properties of the chloride system anode electrolyte, alkali metal fluoride, alkaline earth metal fluoride, aluminum fluoride can be added to the chloride system, alkali metal oxide, alkaline earth metal oxide. Carbon conductive agent or metal powder can also be mixed into the aluminum-silicon oxide material, and the aluminum-silicon oxide material can be shaped and sintered to improve the electrochemical reactivity of the aluminum-silicon oxide material at the interface.

[0040] According to the method for producing metal aluminum and polycrystalline silicon from high-silicon aluminum-containing resources according to the specific embodiment of the present application, in step (2), the cathode electrolyte is composed of 20-70wt% weighting agent, 15-50wt% AlF3, 13-40wt% NaF, and an additive with a content of not more than 20wt%; the weighting agent is BaCl2 or / and BaF2, and the additive is one or more of LiF, Li3AlF6, Na3AlF6, CaF2, MgF2, NaCl, LiCl, CaCl2, and MgCl2;

[0041] Preferably, the cathode electrolyte is 20-40wt% BaF2, 15-50wt% AlF3, 20-40wt% NaF, and 10-20wt% CaF2, or is 50-65wt% BaCl2, 15-30wt% AlF3, 13-30wt% NaF, and 0-5wt% NaCl.

[0042] In the cathode chamber, aluminum atoms in the copper-aluminum alloy are discharged at the interface between the copper-aluminum alloy and the cathode electrolyte, and the generated Al 3+ (Al 3+ represents AlF4 - and all other aluminum-containing ions, the same below) enters the cathode electrolyte, and the Al 3+The aluminum atoms are reduced at the interface between the cathode or the molten aluminum and the cathode electrolyte and enter the molten aluminum product. The reaction formula is:

[0043] Interface: Al (copper-aluminum alloy) - 3e - → Al 3+

[0044] Cathode: Al 3+ + 3e - → Al (molten aluminum)

[0045] In the molten copper-aluminum alloy, the molar concentration and electrochemical activity of silicon atoms are both lower than those of aluminum atoms. Therefore, at the interface between the copper-aluminum alloy and the cathode electrolyte, the aluminum atoms are discharged rather than the silicon atoms and other more inert impurities (e.g., Fe, Mn). Thus, the purity of the molten aluminum obtained by reduction in the cathode chamber can reach 99.0 wt% or above.

[0046] As the electrolysis proceeds, the aluminum-silicon oxide in the anode chamber is continuously reduced into aluminum atoms and silicon atoms and enters the copper-aluminum alloy, while in the cathode chamber, the aluminum in the copper-aluminum alloy is continuously oxidized and enters the cathode electrolyte, and the silicon is retained and enriched in the copper-aluminum alloy, which gradually changes into a copper-aluminum-silicon alloy.

[0047] When the Si content in the copper-aluminum-silicon alloy is not high (Si < 5 at%), it can be directly retained in the double-chamber electrolytic cell for continuous work, or the molten aluminum can be supplemented in time to adjust the composition and melting point of the copper-aluminum-silicon alloy, and the silicon continues to be enriched in the alloy phase in the double-chamber electrolytic cell. When the Si content in the copper-aluminum-silicon alloy is high (e.g., Si > 5 at%), part or all of the copper-aluminum-silicon alloy at the bottom of the double-chamber electrolytic cell is extracted and placed in a single-chamber electrolytic cell to prepare an aluminum-silicon alloy and / or polycrystalline silicon by a molten salt electrolysis method.

[0048] According to the method for producing molten aluminum and polycrystalline silicon from high-silicon aluminum-containing resources according to the specific embodiment of the present application, in step (3), the bottom layer of the single-chamber electrolytic cell is a copper-aluminum-silicon alloy anode, the middle layer is a refining electrolyte, and the upper layer is an aluminum liquid cathode. Under the condition of power supply, the Al and Si in the copper-aluminum-silicon alloy are sequentially oxidized and enter the refining electrolyte, and an aluminum-silicon alloy and / or polycrystalline silicon is obtained by reduction at the aluminum liquid cathode.

[0049] According to the method for producing molten aluminum and polycrystalline silicon from high-silicon aluminum-containing resources according to the specific embodiment of the present application, in step (3), the aluminum liquid cathode is pure molten aluminum or molten aluminum containing silicon. The aluminum liquid cathode can be pre-added or gradually generated during electrolysis.

[0050] According to the method for producing metal aluminum and polysilicon from high-silicon aluminum-containing resources according to the specific embodiment of the present application, in step (3), the refining electrolyte is composed of 20-40wt% BaF2, 40-70wt% cryolite, 5-25wt% AlF3, 0-10wt% fluorosilicon compound and 0-15wt% additive; the cryolite is one or more of Na3AlF6, Li3AlF6 and K3AlF6; the fluorosilicon compound is one or more of Na2SiF6, K2SiF6, Li2SiF6 and SiF4; and the additive is one or more of LiF, NaF, KF, CaF2 and MgF2.

[0051] The reaction principle in the single-chamber electrolytic cell can be summarized as follows: when the liquid copper-aluminum-silicon alloy is used as the anode, the aluminum atoms and silicon atoms therein are oxidized into aluminum ions and silicon ions and enter the refining electrolyte, but since the aluminum has stronger electrochemical activity, it is generally preferentially oxidized and enters the refining electrolyte, and then the oxidation of the silicon atoms occurs. The aluminum ions and silicon ions in the refining electrolyte are reduced into aluminum atoms and silicon atoms at the cathode. If the aluminum liquid cathode is pure metal aluminum liquid, the aluminum atoms and silicon atoms will melt into the aluminum liquid to form liquid aluminum-silicon alloy; if the aluminum liquid cathode is metal aluminum liquid containing silicon, the silicon is continuously enriched therein and eventually saturated, and then the polysilicon is precipitated. The reaction formula is as follows:

[0052] Anode: Al (copper-aluminum-silicon alloy) - 3e - → Al 3+

[0053] Si (copper-aluminum-silicon alloy) - 4e - → Si 4+

[0054] Cathode: Al 3+ + 3e - → Al (metal aluminum or aluminum-silicon alloy)

[0055] Si 4+ + 4e - → Si (aluminum-silicon alloy or / and polysilicon)

[0056] After sufficient electrolysis, the aluminum and most of the silicon in the copper-aluminum-silicon alloy can be removed to form crude copper containing a small amount of silicon.

[0057] According to the method for producing metal aluminum and polysilicon from high-silicon aluminum-containing resources according to the specific embodiment of the present application, in step (3), when the single-chamber electrolytic cell is normally working, the anode current density is 0.01-1.0 A / cm 2 , and the temperature is 800-1100℃.

[0058] According to the method for producing metal aluminum and polysilicon from high-silicon aluminum-containing resources according to the specific embodiment of the present application, in step (3), the aluminum-silicon alloy is used to produce polysilicon by a physical method or / and a chemical method, the physical method includes one or more of a liquation method, a condensation method, a vacuum distillation method, and a directional solidification method, and the chemical method includes an acid pickling method and an electrolytic refining method, and the physical method is preferred.

[0059] The polysilicon and crude aluminum obtained after the aluminum-silicon alloy is separated by the physical method can be used to produce and process aluminum alloy materials according to the specific composition, and can also be used to be melted with the above-mentioned crude copper to form a copper-aluminum alloy and returned to step (2) for use.

[0060] Therefore, there are two ways to produce polysilicon: polysilicon directly obtained in the single-tank electrolysis chamber, and polysilicon obtained after the aluminum-silicon alloy is separated by the physical method.

[0061] The present application has the following beneficial effects:

[0062] (1) The process of producing aluminum-silicon oxide materials from high-silicon aluminum-containing resources only needs simple pretreatment or leaching solution without a deep desiliconization / iron removal process, and fully utilizes the aluminum and silicon elements in the high-silicon aluminum-containing resources, which not only reduces the generation of waste residues and the pressure of the impurity removal process, but also obtains metal aluminum, polysilicon, and aluminum-silicon alloy products, and has strong economic efficiency.

[0063] (2) The electrolysis process is continuous and has strong operability. For the double-chamber electrolysis tank and the single-chamber electrolysis tank, continuous feeding and continuous discharging can be realized, and the copper element is closed-circulated. In addition, the traditional electrolysis tank requires that the aluminum oxide has a certain solubility and dissolution rate in the electrolyte, otherwise the unsolved aluminum oxide material will pass through the cathode aluminum liquid to form a crust at the bottom of the tank, affecting the normal work of the electrolysis tank. The bottom layer of the double-chamber electrolysis tank used in the present application is a liquid copper-aluminum alloy, which has a greater density than the density of the electrolyte or the aluminum-silicon oxide material. Even if the aluminum-silicon oxide material is locally added in excess, it will also remain at the interface between the copper-aluminum alloy and the electrolyte, and continue to participate in the dissolution or electrochemical reaction. This not only improves the operation adaptability of the electrolysis tank, but also improves the direct utilization rate of the aluminum-silicon oxide material.

[0064] (3) The electrolytic cell has the function of purifying and removing impurities. Both the double-chamber electrolytic cell and the single-chamber electrolytic cell have the function of removing impurities. In the double-chamber electrolytic cell, the liquid copper-aluminum alloy is in contact with the electrolyte and forms an electrochemical reaction interface, in which the impurities (such as Ca, Na) more active than Al and Si are intercepted in the anode electrolyte, and the impurities (such as Fe, Mn) less active than Al and Si are enriched in the copper-aluminum alloy, so that the impurities in the raw material and the impurities generated by the corroded inert anode can be effectively controlled, and the purity of the liquid aluminum in the cathode chamber is ensured to be ≥99.0wt%. In the single-chamber electrolytic cell, the inert impurities enriched in the copper-aluminum-silicon alloy are difficult to precipitate, and have little effect on the purity of the aluminum-silicon alloy or / and polycrystalline silicon as the cathode product.

[0065] (4) Energy saving, environmental protection and clean production. In the aluminum oxide industry, not only can the difficult-to-handle natural high-silicon bauxite and solid waste such as fly ash, coal gangue and the like be used to produce aluminum-silicon oxide materials, but also the waste generated by the deep impurity removal process can be avoided; in the electrolytic aluminum industry, the low-temperature electrolyte and the inert anode are used in combination in the electrolytic cell according to the present application, which can not only improve the electric energy efficiency and current efficiency, but also reduce the generation of greenhouse gases, toxic gases, residual anodes and waste cathode carbon blocks. BRIEF DESCRIPTION OF DRAWINGS

[0066] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0067] Figure 1 The process flow for producing metal aluminum and polycrystalline silicon from high-silicon aluminum-containing resources;

[0068] Figure 2 The cross-sectional view of the double-chamber electrolytic cell according to the present application is shown in the figure.

[0069] Figure Figure 2 Mark: 1-insulating partition, 2-cathode, 3-metal aluminum, 4-cathode electrolyte, 5-copper-aluminum alloy, 6-electrolytic cell body, 7-anode electrolyte, 8-anode.

[0070] Figure 3 The cross-sectional view of the single-chamber electrolytic cell according to the present application is shown in the figure.

[0071] Figure Figure 3 Mark: 9-cathode, 10-aluminum liquid, 11-refining electrolyte, 12-copper-aluminum-silicon alloy, 13-conductive carbon block, 14-conductive steel rod, 15-electrolytic cell body, 16-insulating refractory brick lining. DETAILED DESCRIPTION

[0072] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described in detail below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0073] As shown in Figure 1 The method for producing metal aluminum and polysilicon from high-silicon aluminum-containing resources mainly comprises the following steps:

[0074] Step (1): obtaining aluminum-silicon oxide material from high-silicon aluminum-containing resources through a pretreatment process;

[0075] Step (2): preparing metal aluminum and copper-aluminum-silicon alloy from the aluminum-silicon oxide material through a molten salt electrolysis method in a double-chamber electrolytic cell;

[0076] Step (3): taking out the copper-aluminum-silicon alloy and placing it in a single-chamber electrolytic cell to prepare aluminum-silicon alloy or / and polysilicon through a molten salt electrolysis method.

[0077] In step (1), the mass ratio of Al2O3 / SiO2 in the high-silicon aluminum-containing resources is 1:0.5-1:7, including one or more of high-silicon bauxite, fly ash, coal gangue, kaolin and alunite; the content of Al2O3+SiO2 in the aluminum-silicon oxide material is ≥90.0wt%, and the content of Al2O3 is ≥40.0wt%, and the content of SiO2 is ≥0.1wt%. The pretreatment process includes alkali method, acid method and acid-alkali combined method, which is characterized by not needing a deep desiliconization process or not needing a deep iron / calcium removal process.

[0078] In step (2), the double-chamber electrolytic cell is as shown in the accompanying drawings Figure 2 As shown in the accompanying drawings, the electrolytic cell body 6 is divided into an anode chamber and a cathode chamber by an insulating partition 1 to physically separate the anode electrolyte 7 from the cathode electrolyte 4, the anode chamber is provided with an anode 8 (carbon anode or inert anode), the cathode chamber is provided with a cathode 2 (ordinary graphite cathode or wettable cathode), and the double-chamber electrolytic cell is also provided with a copper-aluminum alloy 5 at the bottom, and the copper-aluminum alloy 5 is in contact with the anode electrolyte 7 and the cathode electrolyte 4, respectively.

[0079] The operating condition is to pass current at a temperature of 800-1000℃, and the anode current density is controlled to be 0.1-1.5A / cm 2An aluminum-silicon oxide is introduced into the anode chamber, where an oxidation reaction occurs and gas is released. Aluminum ions (dissolved and / or undissolved) and silicon ions (dissolved and / or undissolved) in the anode chamber are reduced to aluminum atoms and silicon atoms, respectively, at the interface between the anode electrolyte 7 and the copper-aluminum alloy 5, and enter the liquid copper-aluminum alloy 5. In the cathode chamber, aluminum atoms in the copper-aluminum alloy 5 discharge at the interface between the cathode electrolyte 4 and the copper-aluminum alloy 5 to form aluminum ions, which enter the cathode electrolyte 4. The aluminum ions in the cathode electrolyte are reduced to aluminum atoms, forming liquid metallic aluminum 3, which floats on top of the cathode electrolyte 4. As the electrolysis process continues, silicon is continuously enriched in the copper-aluminum alloy 5, gradually transforming it into a copper-aluminum-silicon alloy.

[0080] If the Si content in the copper-aluminum-silicon alloy 5 is low (Si < 5 at%), it can be directly retained in the double-chamber electrolytic cell to continue working, or metallic aluminum can be added in time to adjust the composition and melting point of the copper-aluminum-silicon alloy, and then it can continue to work in the double-chamber electrolytic cell to allow silicon to continue to accumulate in the alloy; when the Si content in the copper-aluminum-silicon alloy is high (such as Si > 5 at%), part or all of the copper-aluminum-silicon alloy 5 at the bottom of the double-chamber electrolytic cell can be extracted and placed in a single-chamber electrolytic cell to prepare aluminum-silicon alloy and / or polycrystalline silicon by molten salt electrolysis.

[0081] In step (3), the single-chamber electrolytic cell is as follows: Figure 3 As shown, the bottom structure of the electrolytic cell 15 is a conductive carbon block 13 with conductive steel rods 14, and the inner walls are lined with insulating refractory bricks 16. The bottom melt is a copper-aluminum-silicon alloy 12 as the anode, the middle melt is a refined electrolyte 11, and the upper melt is an aluminum liquid 10 (pure aluminum liquid or aluminum-silicon alloy liquid) connected to the cathode 9.

[0082] It operates under power at temperatures ranging from 800 to 1100°C, with the anode current density controlled at 0.01 to 1.0 A / cm². 2 In the copper-aluminum-silicon alloy 12, Al and Si are oxidized sequentially and enter the refined electrolyte 11, and reduced at the cathode aluminum liquid 10 to obtain aluminum-silicon alloy and / or polycrystalline silicon.

[0083] The resulting aluminum-silicon alloy is used to produce polycrystalline silicon through physical and / or chemical methods. Physical methods include one or more of melting, condensation, vacuum distillation, and directional solidification, while chemical methods include pickling and electrolytic refining, with physical methods being preferred.

[0084] After full electrolysis in a single-chamber electrolytic cell, aluminum and most of the silicon in the copper-aluminum-silicon alloy can be removed to form crude copper containing a small amount of silicon. The byproduct obtained by physical separation of aluminum-silicon alloy is crude aluminum containing or without silicon. After mixing crude aluminum and crude copper, they become copper-aluminum alloy and are returned to step (2) for use, thus completing the closed-loop cycle of copper element.

[0085] Example 1

[0086] The high-alumina coal gangue (Al2O3 content of 42.7 wt%, Al / Si ratio of 1.5) was calcined at 950°C for 1.5 h, then ball-milled, washed with dilute hydrochloric acid, and pre-desiliconized with 20% NaOH solution at 100°C for 1 h. The desiliconized ash was mixed with non-metallurgical grade alumina (Al2O3 content of 95.9 wt%, SiO2 content of 0.20 wt%) to obtain an aluminum-silicon-oxide material with Al2O3 content of 86.5 wt% and SiO2 content of 7.8 wt%.

[0087] The bottom of the double-chamber electrolytic cell contained a pre-alloyed Cu-Al alloy with Al content of 55 at%, the anode was graphite, and the cathode was graphite. The anode electrolyte composition was: 81 wt% Na3AlF6+ 8 wt% AlF3+ 3 wt% Al2O3+ 6 wt% KF+ 2 wt% CaF2+ 2 wt% LiF; the cathode electrolyte composition was: 23 wt% BaF2+ 27 wt% AlF3+ 37 wt% NaF+ 13 wt% CaF2. The double-chamber electrolytic cell was heated to 1000°C and kept for 2 h, and direct current was passed to control the anode current density at 1.5 A / cm2. The electrolysis was started, and the aluminum-silicon-oxide material was added periodically after the electrolysis started. The total electrolysis time was 60 h. After the electrolysis, the Al content in the cathode product, metallic aluminum, was determined to be 99.974 wt%. 2

[0088] After the electrolysis, the copper-aluminum alloy in the bottom of the double-chamber electrolytic cell was converted into a copper-aluminum-silicon alloy with Si content of 7.6 at%. The copper-aluminum-silicon alloy was taken out and placed in the bottom of a single-chamber electrolytic cell as an anode, and a graphite rod was used as a cathode. The refining electrolyte was 30 wt% BaF2+ 32 wt% Na3AlF6+ 30 wt% Li3AlF6+ 5 wt% AlF3+ 3 wt% Na2SiF6. The single-chamber electrolytic cell was heated to 1000°C and kept for 2 h. The temperature of the first-stage electrolysis was 1000°C, the time was 3.5 h, and the anode current density was 0.8 A / cm2. After the electrolysis, the cathode product, metallic aluminum, was taken out. The temperature of the second-stage electrolysis was increased to 1100°C, the electrolysis time was 3 h, and the anode current density was 0.2 A / cm2. 2 2 The liquid aluminum-silicon alloy and solid polycrystalline silicon particles were obtained at the cathode.

[0089] The obtained aluminum-silicon alloy was first subjected to a condensation method to obtain a polycrystalline silicon ingot. The polycrystalline silicon ingot and the solid polycrystalline silicon particles were subjected to remelting, slow cooling, and directional solidification to obtain polycrystalline silicon with purity of 99.9%.

[0090] Example 2

[0091] The high-silicon bauxite (Al2O3 content of 62.8 wt%, Al / Si ratio of 5.5) was finely ground and desiliconized with Na2O k ​​The Cu-Al alloy in the bottom of the double-chamber electrolytic cell is converted into a Cu-Al-Si alloy with Si content less than 0.1 at%, thus the above-mentioned electrolysis experiment can still be carried out for a long time, and metal aluminum is continuously obtained in the cathode chamber and silicon is enriched in the alloy. When the silicon content in the Cu-Al-Si alloy is not less than 5 at%, the Cu-Al-Si alloy is used as an anode to extract an Al-Si alloy or / and polycrystalline silicon by a single-chamber electrolytic cell electrolysis method.

[0092] The Cu-Al alloy in the bottom of the double-chamber electrolytic cell is converted into a Cu-Al-Si alloy with Si content less than 0.1 at%, thus the above-mentioned electrolysis experiment can still be carried out for a long time, and metal aluminum is continuously obtained in the cathode chamber and silicon is enriched in the alloy. When the silicon content in the Cu-Al-Si alloy is not less than 5 at%, the Cu-Al-Si alloy is used as an anode to extract an Al-Si alloy or / and polycrystalline silicon by a single-chamber electrolytic cell electrolysis method. 2 The Cu-Al alloy in the bottom of the double-chamber electrolytic cell is converted into a Cu-Al-Si alloy with Si content less than 0.1 at%, thus the above-mentioned electrolysis experiment can still be carried out for a long time, and metal aluminum is continuously obtained in the cathode chamber and silicon is enriched in the alloy. When the silicon content in the Cu-Al-Si alloy is not less than 5 at%, the Cu-Al-Si alloy is used as an anode to extract an Al-Si alloy or / and polycrystalline silicon by a single-chamber electrolytic cell electrolysis method.

[0093] The Cu-Al alloy in the bottom of the double-chamber electrolytic cell is converted into a Cu-Al-Si alloy with Si content less than 0.1 at%, thus the above-mentioned electrolysis experiment can still be carried out for a long time, and metal aluminum is continuously obtained in the cathode chamber and silicon is enriched in the alloy. When the silicon content in the Cu-Al-Si alloy is not less than 5 at%, the Cu-Al-Si alloy is used as an anode to extract an Al-Si alloy or / and polycrystalline silicon by a single-chamber electrolytic cell electrolysis method.

[0094] Example 3

[0095] The fly ash (Al2O3 content is 35.3 wt%, aluminum-silicon ratio is 0.6) is leached with hydrochloric acid with a concentration of about 30%, liquid-solid ratio is 5 mL / g, temperature is 95℃, and time is 3h. After leaching, the crude aluminum chloride solution is separated by filtration. The crude aluminum chloride solution does not need iron / calcium removal process by ion exchange method or precipitation method, and is directly concentrated by evaporation under negative pressure to obtain aluminum chloride crystals. The aluminum chloride crystals are calcined at 500℃ and 1000℃ in two stages to obtain alumina material. Then some silicon-containing leaching residue is added to obtain aluminum-silicon oxide material, in which Al2O3 content is 82.7 wt%, SiO2 content is 10.3 wt%, and Fe2O3 content is 1.1 wt%.

[0096] The Cu-Al alloy in the bottom of the two-compartment cell is pre-alloyed with 70 at% Al. The anode is a CaRuO3 ceramic material inert anode and the cathode is a TiB2-coated graphite. The anolyte is CaCl2-LiCl with a molar ratio of 70:30 and the catholyte is composed of 25wt% BaF2+40wt% AlF3+25wt% NaF+10wt% CaF2. The two-compartment cell is heated to 820°C and kept for 2h. Direct current is passed to control the anode current density at 0.2 A / cm 2 The Al-Si oxide feed is added periodically before and after the electrolysis. The total electrolysis time is 24h. After the electrolysis, the Al content in the cathode product, metallic aluminum, is determined to be 99.976wt%.

[0097] The Cu-Al alloy in the bottom of the two-compartment cell is pre-alloyed with 70 at% Al. The anode is a CaRuO3 ceramic material inert anode and the cathode is a TiB2-coated graphite. The anolyte is CaCl2-LiCl with a molar ratio of 70:30 and the catholyte is composed of 25wt% BaF2+40wt% AlF3+25wt% NaF+10wt% CaF2. The two-compartment cell is heated to 820°C and kept for 2h. Direct current is passed to control the anode current density at 0.2 A / cm

[0098] Example 4

[0099] The Al-Si oxide feed is obtained after the acid washing of the high-alumina fly ash (Al2O3 content of 49.0wt%, Al / Si ratio of 1.1) to remove impurities. The Al2O3 content is 48.4wt% and the SiO2 content is 47.3wt%.

[0100] The Cu-Al alloy in the bottom of the two-compartment cell is pre-alloyed with 65 at% Al. The anode is graphite and the cathode is TiB2 / C composite material. The anolyte is CaCl2 and the catholyte is composed of 60wt% BaCl2+20wt% AlF3+20wt% NaF. The two-compartment cell is heated to 860°C and kept for 2h. Direct current is passed to control the anode current density at 1.0 A / cm 2 The Al-Si oxide feed is added periodically before and after the electrolysis. The total electrolysis time is 24h. After the electrolysis, the Al content in the cathode product, metallic aluminum, is determined to be 99.976wt%.

[0101] After electrolysis, the Cu-Al alloy at the bottom of the two-compartment cell is converted into a Cu-Al-Si alloy with 9.2 at% Si. The Cu-Al-Si alloy is taken out and placed at the bottom of a single-compartment cell as an anode, and a graphite rod as a cathode. The refining electrolyte is 25wt% BaF2+50wt% Na3AlF6+15wt% AlF3+5wt% K2SiF6+3wt% CaF2+2wt% LiF. The single-compartment cell is heated to 900°C and kept for 2h. The temperature of the first-stage electrolysis is 880°C, and the time is 6h. The anode current density is 1.0 A / cm 2 After electrolysis, the cathode product, aluminum, is taken out. The temperature of the second-stage electrolysis is increased to 1050°C, and the time is 4h. The anode current density is 0.5 A / cm 2 The aluminum-silicon alloy is obtained at the cathode.

[0102] The obtained aluminum-silicon alloy is subjected to vacuum distillation (1100°C, maintaining the gas pressure <1 Pa) to obtain polycrystalline silicon with a purity of 99.9%.

[0103] Example 5

[0104] After fine grinding, the fly ash (Al2O3 content of 49.8wt%, aluminum-silicon ratio of 1.2) is subjected to pre-desiliconization treatment with a 20% NaOH solution at 120°C. The desiliconized liquid and desiliconized ash are obtained by filtration. The desiliconized ash is subjected to leaching with a Na2O k =230g / L NaOH solution at 250°C. The leaching slurry is subjected to dilution and filtration to obtain a sodium aluminate solution and a leaching residue. The leaching residue is treated by the soda-lime sintering method to further recover Al2O3 therein. The sodium aluminate solution is not subjected to lime deep desiliconization treatment. The solution is cooled to 75°C and then seeded with solid aluminum hydroxide to obtain solid aluminum hydroxide. The solid aluminum hydroxide is mixed with white carbon black and calcined at 900°C to obtain aluminum-silicon oxide material, wherein the Al2O3 content is 90.4% and the SiO2 content is 5.6%.

[0105] The two-compartment cell contains a pre-alloyed Cu-Al alloy at the bottom, wherein the Al content is 60 at%. The anode is a 5wt% Ni-10wt% NiO-NiFe2O4 metal ceramic composite inert anode, and the cathode is a TiB2-coated graphite. The anode electrolyte composition is: 82wt% Na3AlF6+12wt% AlF3+2wt% Al2O3+2wt% CaF2+1wt% MgF2+1wt% LiF, and the cathode electrolyte composition is: 35wt% BaF2+30wt% AlF3+30wt% NaF+5wt% CaF2. The two-compartment cell is heated to 950°C and kept for 2h. The anode current density is controlled at 0.8 A / cm 2The aluminum-silicon oxide was added periodically after the electrolysis began, and the total electrolysis time was 16 hours. After the electrolysis was completed, the Al content in the cathode product was measured to be 99.983 wt%.

[0106] The copper-aluminum alloy at the bottom of the dual-chamber electrolytic cell transforms into a copper-aluminum-silicon alloy with a Si content of 0.5 at%. Therefore, the above electrolysis experiment can continue for a long time, continuously obtaining metallic aluminum in the cathode chamber and enriching silicon in the alloy. When the silicon content in the copper-aluminum-silicon alloy is not less than 5 at%, aluminum-silicon alloy and / or polycrystalline silicon are extracted by electrolysis in a single-chamber electrolytic cell using the copper-aluminum-silicon alloy as the anode.

[0107] Example 6

[0108] Alumina material produced from high-alumina fly ash (Al2O3 content 45.2 wt%, aluminum-silicon ratio 1.2) using the alkaline leaching pre-desiliconization-soda lime sintering method: The high-alumina fly ash raw material was pre-desiliconized with NaOH solution (temperature 120℃, time 30 min). The filtered desiliconized ash was mixed with limestone, raw coal, Na2CO3, etc. to form raw meal. The CaO / (SiO2+TiO2) molar ratio in the raw meal was controlled to be 2.0, and the Na2O / (Al2O3+TiO2) molar ratio was controlled to be 1.2. The raw material (Al2O3 + Fe2O3) molar ratio is 1.0. The raw material is sintered at 1200℃ for 4 hours to become clinker. After the clinker is crushed, it is dissolved in sodium carbonate solution at 80℃. The Al2O3 content in the leaching solution is controlled to be 90-110 g / L. After the leaching solution is filtered, it is directly bubbled with CO2 for carbonation decomposition, filtration, and calcination without going through a lime deep desilication process. The result is an aluminum-silicon oxide with an Al2O3 content of 96.4 wt% and a SiO2 content of 0.42 wt%.

[0109] The bottom of the dual-chamber electrolytic cell contains a pre-alloyed Cu-Al alloy with an Al content of 65 wt%. The anode is an inert anode made of Cu-13 wt% Fe-37 wt% Ni alloy, and the cathode is graphite. The anode electrolyte composition is: 42.3 wt% Na3AlF6 + 28.2 wt% K3AlF6 + 22 wt% AlF3 + 2.5 wt% Al2O3 + 3 wt% CaF2 + 2 wt% LiF. The cathode electrolyte composition is: 22 wt% BaF2 + 46 wt% AlF3 + 26 wt% NaF + 4 wt% CaF2 + 2 wt% LiF. The dual-chamber electrolytic cell is heated to 880℃ and held for 2 hours. Direct current is applied, and the anode current density is controlled at 0.6 A / cm². 2 The aluminum-silicon oxide was added periodically after the electrolysis began, and the total electrolysis time was 10 hours. After the electrolysis was completed, the Al content in the cathode product aluminum was determined to be 99.991 wt%.

[0110] The copper-aluminum alloy at the bottom of the double-chamber electrolytic cell is converted into a copper-aluminum-silicon alloy with a Si content of less than 0.1 at%, so the above-mentioned electrolysis experiment can still be carried out for a long time, continuously obtaining metallic aluminum at the cathode chamber and enriching silicon in the alloy. When the silicon content in the copper-aluminum-silicon alloy is not less than 5 at%, aluminum-silicon alloy or / and polycrystalline silicon is obtained by electrolysis of the copper-aluminum-silicon alloy as an anode through a single-chamber electrolytic cell.

[0111] The above merely provides a specific implementation of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for producing metallic aluminum and polysilicon from high-silicon aluminum-containing resources, characterized in that, The method comprises the following steps: Step (1): obtaining aluminum-silicon oxide material from high-silicon aluminum-containing resources through a pretreatment process; The mass ratio of Al2O3 / SiO2 in the high-silicon aluminum-containing resources is 1:0.5-7, and the high-silicon aluminum-containing resources include one or more of high-silicon bauxite, fly ash, coal gangue, kaolin and alunite; In the aluminum-silicon oxide material, the sum of the contents of Al2O3 and SiO2 is ≥90.0%, the content of Al2O3 is ≥40.0%, and the content of SiO2 is ≥0.1%; Step (2): preparing metallic aluminum and copper-aluminum-silicon alloy from the aluminum-silicon oxide material through a molten salt electrolysis method in a double-chamber electrolytic cell; The double-chamber electrolytic cell is divided into an anode chamber and a cathode chamber to physically separate the anode electrolyte and the cathode electrolyte, the anode chamber is provided with an anode, the cathode chamber is provided with a cathode, and the double-chamber electrolytic cell further contains copper-aluminum alloy at the bottom, and the copper-aluminum alloy is in contact with the anode electrolyte and the cathode electrolyte, respectively; under the condition of power supply operation, the aluminum-silicon oxide material is fed into the anode chamber, metallic aluminum is obtained in the cathode chamber, and the copper-aluminum alloy at the bottom of the double-chamber electrolytic cell is converted into copper-aluminum-silicon alloy; Step (3): taking out the copper-aluminum-silicon alloy and placing it in a single-chamber electrolytic cell to prepare polysilicon through a molten salt electrolysis method; In the single-chamber electrolytic cell, the bottom layer of the melt is a copper-aluminum-silicon alloy anode, the middle layer of the melt is a refining electrolyte, and the upper layer of the melt is an aluminum liquid cathode; the aluminum liquid cathode is a silicon-containing metallic aluminum liquid; Under the condition of power supply operation, Al and Si in the copper-aluminum-silicon alloy are oxidized and enter the refining electrolyte, and polysilicon is obtained by reduction at the aluminum liquid cathode; In step (2), the anode electrolyte is a fluoride system or a chloride system; The fluoride system includes 60-90wt% cryolite, 5-25wt% AlF3, 1-5wt% Al2O3 and 0-15wt% additives; the cryolite is one or more of Na3AlF6, Li3AlF6 and K3AlF6, and the additives are one or more of LiF, NaF, KF, CaF2, MgF2 and BaF2; The chloride system is CaCl2, or the chloride system is composed of CaCl2 and one or more of NaCl, KCl, BaCl2, CaF2, LiCl and CaO; The cathode electrolyte is composed of 20-70wt% weighting agent, 15-50wt% AlF3, 13-40wt% NaF and additives with a content of not more than 20wt%; the weighting agent is BaCl2 or / and BaF2, and the additives are one or more of LiF, Li3AlF6, Na3AlF6, CaF2, MgF2, NaCl, LiCl, CaCl2 and MgCl2; The content of Al in the copper-aluminum alloy is 55-80at%; the copper-aluminum alloy remains in a liquid state during normal electrolysis, and the density of the copper-aluminum alloy is greater than the densities of the anode electrolyte and the cathode electrolyte. In step (3), the refining electrolyte is composed of 20-40wt% BaF2, 40-70wt% cryolite, 5-25wt% AlF3, 0-10wt% fluorosilicate compound and 0-15wt% additive; the cryolite is one or more of Na3AlF6, Li3AlF6 and K3AlF6, the fluorosilicate compound is one or more of Na2SiF6, K2SiF6, Li2SiF6 and SiF4, and the additive is one or more of LiF, NaF, KF, CaF2 and MgF2.

2. The method for producing metallic aluminum and polysilicon from high-silicon aluminum-containing resources according to claim 1, characterized in that, In step (2), the anode is a carbon anode or an inert anode, and the cathode is one of graphite, aluminum or TiB2 / C.

3. The method for producing metallic aluminum and polysilicon from high-silicon aluminum-containing resources according to claim 1, characterized in that, The cathode electrolyte is 20-40wt% BaF2, 15-50wt% AlF3, 20-40wt% NaF and 10-20wt% CaF2, or the cathode electrolyte is 50-65wt% BaCl2, 15-30wt% AlF3, 13-30wt% NaF and 0-5wt% NaCl.

4. The method for producing metallic aluminum and polysilicon from high-silicon aluminum-containing resources according to claim 1, characterized in that, In step (2), the anode current density is 0.1-1.5 A / cm2 and the temperature is 800-1000℃ when the double-chamber electrolytic cell is working normally. 2 , the temperature is 800-1000℃ when the double-chamber electrolytic cell is working normally. In step (3), the single-chamber electrolytic cell is normally operated at an anode current density of 0.01-1.0 A / cm 2 and a temperature of 800-1100°C.

5. The method for producing metallic aluminum and polysilicon from high-silicon aluminum-containing resources according to claim 1, characterized in that, In step (3), the aluminum-silicon alloy is used to produce polysilicon by physical method or / and chemical method, the physical method includes one or more of fractional crystallization, fractional condensation, vacuum distillation and directional solidification, and the chemical method includes pickling and electrolytic refining.

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