Method and device for preparing aluminum from high-aluminum solid waste based on magnesium chloride double circulation

Abstract

The invention provides a method and a device for preparing aluminum from high-aluminum solid waste based on magnesium chloride double circulation, which are characterized in that a carbon-containing material and oxygen are added into a carbonaceous reducing agent dehydrogenation and deashing device to obtain a carbonaceous reducing agent, and the carbonaceous reducing agent, the high-aluminum solid waste and chlorine are added into a carbon chlorination device to obtain aluminum trichloride; the method comprises the following steps: adding aluminum trichloride and metal magnesium liquid into a magnesiothermic reduction device for magnesiothermic reduction to obtain metal aluminum and anhydrous magnesium chloride melt, adding the anhydrous magnesium chloride melt into a magnesium electrolytic cell for electrolysis to obtain metal magnesium liquid and chlorine which are recycled, and introducing a chlorine element for chlorination operation, according to the method, aluminum oxide and silicon oxide are converted into aluminum trichloride and silicon tetrachloride, effective separation of silicon and aluminum is achieved by means of easy gasification and boiling point difference of the aluminum trichloride and the silicon tetrachloride, the aluminum-silicon separation degree can reach 95% or above, metal aluminum is finally obtained, and the low-cost carbonaceous reducing agent is provided.

Description

Technical Field

[0001] The present application relates to the field of comprehensive utilization of high-aluminum solid waste to extract metallic aluminum, and in particular to a method and device for producing aluminum from high-aluminum solid waste based on a magnesium-chlorine dual cycle. Background Art

[0002] High-alumina solid waste is a secondary resource rich in alumina. This includes high-alumina fly ash, high-alumina coal gangue, red mud from the alumina industry, bauxite tailings, and natural minerals, including kaolin, sillimanite, andalusite, and kyanite. The alumina and silica content of high-alumina solid waste typically ranges from 30% to 50%. Alumina is a key mineral resource for metallic aluminum. Extracting aluminum from these high-alumina solid wastes, or extracting alumina first, has become crucial. The technical solutions currently being explored in the industry primarily fall into two categories: hydrometallurgical processes and pyrometallurgical processes, but both have significant limitations.

[0003] While the wet process can produce alumina, it requires the introduction of large amounts of external reagents such as calcium and sodium, causing the remaining silicon oxide to combine with alkali to form new solid waste. This not only fails to reduce solid waste, but actually significantly increases the total amount of solid waste. Furthermore, the alumina produced suffers from problems such as insufficient sphericity and a large angle of repose, making it prone to accumulation and incompatible with the mainstream feeding method of aluminum electrolytic cells, making it difficult to directly apply to electrolytic aluminum production.

[0004] The pyrometallurgical process uses carbon-thermal reduction of aluminum-silicon ore in an electric furnace to produce an aluminum-silicon alloy (containing at least 40% silicon and a target aluminum content of 50%-60%), which is then blended with electrolytic aluminum to produce a cast aluminum alloy. In the pyrometallurgical process, alumina is reduced by carbon at 2000°C, which tends to produce carbides rather than metallic aluminum. Furthermore, iron and silicon are reduced before aluminum, and silicon carbide is more likely to form. Once formed, silicon carbide, due to its hard texture and high density, deposits at the bottom of the furnace, gradually reducing the available space in the furnace. This is commonly known in the industry as "furnace bottom swelling," making smelting unsustainable and forcing the furnace to shut down. In addition, the process has very high requirements for the pelletizing of raw materials, including ingredients, mixing, molding, binder selection and process, pelletizing pressure, drying, etc. Poor control of any link will lead to the failure of reduction smelting. The aluminum content of the alloy that can be smelted is only 30-35%, and the rest is iron and silicon elements. The proportion of aluminum in the alloy is too low, and it is difficult to adjust it into a qualified grade of aluminum alloy with an aluminum content of more than 90%. It can only be used for low-end purposes such as composite deoxidizers, and cannot be used as a mainstream aluminum alloy. The extraction rate of aluminum elements is only 50-65%, and the rest is wasted.

[0005] In summary, the current market processes for recycling aluminum or alumina from high-aluminum solid waste are not mature enough. Summary of the Invention

[0006] The present application provides a method and device for producing aluminum from high-aluminum solid waste based on a magnesium-chlorine dual circulation method. The method adopts a magnesium-chlorine dual circulation method, introduces chlorine element for chlorination operation, so that aluminum oxide and silicon oxide are converted into aluminum trichloride and silicon tetrachloride, and utilizes their easy gasification and boiling point difference to achieve effective separation of silicon and aluminum elements. The degree of aluminum-silicon separation can reach more than 95%, and metallic aluminum is finally obtained, and a low-cost carbonaceous reducing agent is provided.

[0007] In order to achieve the above objectives, the present technical solution provides a method for producing aluminum from high-aluminum solid waste based on a magnesium-chlorine dual cycle, comprising: Adding high-aluminum solid waste, a carbonaceous reducing agent, and chlorine gas to a liquid molten pool containing CaCl2 molten salt or KCl-NaCl-CaCl2 molten salt for carbonization and chlorination to obtain volatile aluminum trichloride, wherein the temperature of the liquid molten pool is 900-1200°C, wherein the carbonaceous reducing agent is obtained by adding a carbon-containing material and oxygen into a closed molten salt bath for pyrolysis and carbonization, the molten salt bath is filled with KCl-NaCl-CaCl2 molten salt, and the temperature of the KCl-NaCl-CaCl2 molten salt is 850-1050°C, wherein the carbon-containing material is any one or a combination of two or more of ordinary anthracite, bituminous coal, coke, semi-coke, waste plastics, waste rubber, biomass carbon, dry organic waste, and waste textiles; Condensing volatile aluminum trichloride to obtain condensed aluminum trichloride; The metallic magnesium liquid and condensed aluminum trichloride are subjected to magnesium thermal reduction to obtain metallic aluminum and anhydrous magnesium chloride melt; The magnesium chloride melt is placed in a magnesium electrolysis cell for electrolysis to obtain recycled chlorine gas and metallic magnesium liquid.

[0008] In the second aspect, this solution provides a high-aluminum solid waste aluminum production device based on magnesium-chlorine dual circulation, comprising: A carbonaceous reducing agent dehydrogenation and deashing device for producing a carbonaceous reducing agent, comprising a molten salt bath carbon material dehydrogenation furnace with a built-in molten salt bath, a carbon material sealed pressurized material tank containing carbon-containing materials, and an oxygen lance with the end immersed in the molten salt bath, wherein the molten salt bath comprises a molten salt of KCl-NaCl-CaCl2, a closed pressurized gas is passed through the carbon material sealed pressurized material tank, and the carbon-containing materials are any one or a combination of two or more of ordinary anthracite, bituminous coal, coke, semi-coke, waste plastics, waste rubber, biomass carbon, dry organic waste, and waste textiles; a carbonizing and chlorinating device for chlorinating high-aluminum solid waste, comprising a chlorination furnace with a built-in liquid molten pool, a condensing device connected to the chlorination furnace, a gas cluster lance and a solid powder cluster lance with the end immersed in the liquid molten pool, The liquid molten pool is filled with CaCl2 molten salt or KCl-NaCl-CaCl2 molten salt, and the temperature of the liquid molten pool is 900~1200℃; a magnesia thermal reduction device for magnesia thermal reduction of aluminum trichloride includes a magnesia thermal aluminum reduction furnace filled with metallic magnesium liquid; a magnesium electrolytic cell for electrolyzing metallic magnesium liquid; carbon-containing material and oxygen are added to a carbonaceous reducing agent dehydrogenation and deashing device to obtain a carbonaceous reducing agent, the carbonaceous reducing agent, high-aluminum solid waste and chlorine are added to a carbonization and chlorination device to obtain aluminum trichloride, the aluminum trichloride and metallic magnesium liquid are added to the magnesia thermal reduction device for magnesia thermal reduction to obtain metallic aluminum and anhydrous magnesium chloride melt, and the anhydrous magnesium chloride melt is added to the magnesium electrolytic cell for electrolysis to obtain recycled metallic magnesium liquid and chlorine.

[0009] Compared with the existing technology, this technical solution has the following characteristics and beneficial effects: This scheme adopts a high-aluminum solid waste aluminum production method based on magnesium-chlorine dual circulation to extract metallic aluminum from high-aluminum solid waste. Different from traditional wet processes and pyrometallurgical processes, the solid waste reduction is significant: after extracting metallic aluminum and silicon products, the solid waste is reduced by 85-90%. Compared with the wet process of extracting alumina, the total amount of solid waste increases instead of decreases. The final solid waste volume is 150-200% of the original aluminum-containing solid waste. The extraction rate of aluminum can be as high as over 90% and the purity reaches over 99%. In addition, the other alloying elements, silicon and magnesium, also meet the content requirements of alloying elements in common aluminum alloys, thereby improving the resource recovery rate in high-aluminum solid waste.

[0010] In addition, the reaction temperature and main process operating temperature of the high-aluminum solid waste aluminum production method based on magnesium-chlorine dual circulation provided by this scheme are greatly reduced, and the equipment is easy to achieve industrialization, large-scale and continuous production. In this process equipment, the temperature of the chlorination furnace is 900-1200°C, and the magnesium thermal reduction furnace and magnesium electrolytic cell only need to be around 700°C. The temperature is far lower than the process requirement of carbon reduction smelting aluminum silicon alloy of 2000°C, and even lower than the temperature of 1500-1600°C in conventional ferrous metallurgy ironmaking and steelmaking. The requirements for equipment are greatly reduced, and volatile green new energy electricity such as wind power and photovoltaics can be utilized. The core power consumption link is magnesium electrolysis. Due to the low melting point and low operating temperature of magnesium electrolyte, it can adapt to power load adjustment and power fluctuations better than electrolytic aluminum. Even power outages and insulation can adapt, while power outages in electrolytic aluminum will cause catastrophic accidents and heavy losses, so that this aluminum production method has industrial applicability.

[0011] Furthermore, this solution utilizes a molten salt bath to treat low-quality carbonaceous materials for dehydrogenation and deashing, resulting in a low-cost, high-quality, pure carbon reducing agent. The resulting carbonaceous reducing agent has an extremely low hydrogen content, eliminating the generation of large amounts of hydrogen chloride in the chlorination furnace and saving environmental treatment costs. Dioxin formation can be effectively suppressed in molten baths exceeding 850°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 It is a structural schematic diagram of a carbonaceous reducing agent dehydrogenation and deashing device.

[0013] Figure 2 It is a structural diagram of the carbonation and chlorination unit.

[0014] Figure 3 It is a schematic diagram of the material beam spray gun P and the gas beam spray gun G.

[0015] Figure 4 It is a schematic diagram of the combined condensation and subsequent distillation separation of aluminum silicon chlorides.

[0016] Figure 5 It is a structural diagram of the combined condenser.

[0017] Figure 6 It is a schematic diagram of the structure of the combined condenser and distiller.

[0018] Figures 7 to 10 This is a schematic diagram of the magnesium thermal aluminum smelting process using aluminum chloride as raw material.

[0019] Figure 11It is a structural diagram of a carbonaceous reducing agent dehydrogenation and deashing device and obtaining the carbonaceous reducing agent after centrifugal solid-liquid separation.

[0020] Figure 12 This is a schematic diagram of a chlorination and magnesium thermal aluminum smelting process apparatus containing an alkali metal chloride molten salt bath.

[0021] Figures 13 to 16 It is a schematic diagram of the aluminum smelting process using aluminum-magnesium thermal method containing alkali metal chloride.

[0022] Figure 17 It is a schematic diagram of the overall process of the method for producing aluminum from high-aluminum solid waste based on magnesium-chlorine dual circulation.

[0023] Figure 18 This is a schematic diagram of the silicon chlorination and magnesium thermal reduction cycle process.

[0024] Figures 19 to 22 This is a schematic diagram of the magnesium thermal silicon smelting process using silicon tetrachloride as raw material.

[0025] Figure 23 This is a schematic diagram of a high-temperature centrifuge separating aluminum-magnesium alloy and magnesium chloride.

[0026] Figures 24 to 25 It is a schematic diagram of the process of preparing different grades of white carbon black from liquid silicon tetrachloride.

[0027] In the figure: 101 - chlorination furnace, 102 - liquid bath, 103 - first stage condenser, 104 - second stage condenser, 105 - gas washing tower, 120 - solid residue tank, 121 - residue discharge port, 135 - high-position liquid tank of carbon-containing molten salt, 136 - low-position liquid tank of carbon-depleted molten salt, 148 - potassium sodium chloroaluminate condenser, 149 - high-melting-point chloride pre-condenser, 150 - combined condenser, 151 - solid-liquid mixture of aluminum chloride and silicon tetrachloride, 152 - constant-temperature cooler, 153 - low-temperature heat exchanger, 154 - silicon tetrachloride liquid circulation pipe, 155 - silicon tetrachloride lifting pump, 156 - spray head, 157 - cold brine inlet pipe, 158 - cold brine outlet pipe, 160 - distiller, 162 - heating jacket, 163 - heating heat exchanger, 167 - heating medium inlet pipe, 168 - heating medium outlet pipe, 170 - silicon tetrachloride condenser, 172 - second constant-temperature cooler, 173 - cooling heat exchanger, 177 - second cold brine inlet pipe, 178 - second cold brine outlet pipe, 301 - magnesium electrolytic cell, 401 - magnesium thermal aluminum reduction furnace, 402 - metallic magnesium liquid, 403 - anhydrous magnesium chloride melt, 410 - aluminum liquid tank, 501 - magnesium thermal silicon reduction furnace, 502 - second metallic magnesium liquid, 503 - anhydrous molten magnesium chloride, 510 - magnesium chloride discharge tank, 520 - magnesium chloride condenser, 530 - metallic magnesium condenser, 550 - vacuum pump, 701 - second high-temperature centrifuge, 702 - second centrifuge outer cylinder, 703 - second centrifuge inner cylinder, 901 - molten salt bath carbon material dehydrogenation furnace, 902 - molten salt bath, 903 - cooling dust collector, 910 - oxygen lance, 911 - carbon material lance, 920 - residue tank, 921 - residue discharge pipe, 931 - molten salt discharge pipe, 935 - carbon material closed pressurized tank, 936 - molten salt return tank, 951 - high-temperature centrifuge, 952 - centrifuge outer cylinder, 953 - centrifuge inner cylinder, 981 - carbon-containing molten residue liquid tank. DETAILED DESCRIPTION

[0028] The exemplary embodiments will be described in detail herein with reference to the attached drawings. In the following description, like reference numerals refer to like elements, unless the context clearly dictates otherwise. The following exemplary embodiments are described in enough detail to enable those having ordinary skill in the art to make and use the apparatus and methods in accordance with one or more embodiments of the present description. The embodiments described herein are not meant to represent all embodiments consistent with one or more embodiments of the present description. Rather, they are merely examples of apparatus and methods consistent with some aspects of one or more embodiments of the present description as detailed in the appended claims.

[0029] It should be noted that in other embodiments, the steps of the corresponding method are not necessarily performed in the order shown and described in this specification. In some other embodiments, the method may include more or fewer steps than those described in this specification. In addition, a single step described in this specification may be broken down into multiple steps for description in other embodiments, and multiple steps described in this specification may be combined into a single step for description in other embodiments.

[0030] Example 1 This solution provides a method for producing aluminum from high-aluminum solid waste based on a magnesium-chlorine dual cycle, comprising: Adding high-aluminum solid waste, a carbonaceous reducing agent, and chlorine gas to a liquid molten pool containing CaCl2 molten salt or KCl-NaCl-CaCl2 molten salt for carbonization and chlorination to obtain volatile aluminum trichloride, wherein the carbonaceous reducing agent is obtained by adding a carbon-containing material and oxygen into a closed molten salt bath for pyrolysis and carbonization, the molten salt bath is filled with KCl-NaCl-CaCl2 molten salt, and the temperature of the KCl-NaCl-CaCl2 molten salt is 850-1050°C, wherein the carbon-containing material is any one or a combination of two or more of ordinary anthracite, bituminous coal, coke, semi-coke, waste plastics, waste rubber, biomass carbon, dry organic waste, and waste textiles; Condensing volatile aluminum trichloride to obtain condensed aluminum trichloride; The metallic magnesium liquid and condensed aluminum trichloride are subjected to magnesium thermal reduction to obtain metallic aluminum and anhydrous magnesium chloride melt; The magnesium chloride melt is placed in a magnesium electrolysis cell for electrolysis to obtain recycled chlorine gas and metallic magnesium liquid.

[0031] This scheme adopts a magnesium-chlorine dual circulation method, introducing chlorine to perform chlorination operations, so that the aluminum oxide and silicon oxide in the high-aluminum solid waste are converted into aluminum trichloride and silicon tetrachloride. Then, by utilizing their easy gasification and boiling point difference, the two elements of silicon and aluminum are effectively separated, and the degree of aluminum-silicon separation can reach more than 95%. Specifically, the chemical thermodynamic property of aluminum oxide being preferentially chlorinated over silicon oxide is utilized to selectively chlorinate the high-aluminum solid waste. Aluminum as the target metal is preferentially converted into aluminum trichloride, while silicon is selectively maintained in its original oxide or chloride state. Therefore, the high-aluminum solid waste can be preferentially reduced to obtain high-purity industrial pure aluminum, and the aluminum content in the aluminum alloy can reach more than 99.8%.

[0032] This solution uses magnesium metal to reduce aluminum trichloride due to the thermodynamically favorable reduction reaction. After magnesium-thermal reduction to obtain aluminum metal, the byproduct magnesium chloride forms a high-purity magnesium chloride melt. This molten magnesium chloride is electrolyzed in a magnesium electrolysis cell to recover chlorine gas and magnesium liquid. The magnesium liquid is used for magnesium-thermal reduction of aluminum chloride, and the chlorine gas is supplied to the chlorination process, achieving a perfect magnesium-chlorine dual cycle. Neither magnesium metal nor liquid chlorine needs to be purchased externally, nor does it require external sales of magnesium metal or chlorine gas consumption. Both magnesium and chlorine are recycled solely within the process. Silicon liquid can be selectively chlorinated, providing a flexible product line. Because silicon is not as widely used as aluminum metal, this solution selectively chlorinates silicon, allowing for either preservation of the silicon oxide in solid form or complete chlorination to produce silicon tetrachloride. Silicon tetrachloride can then be used as a raw material for polysilicon, hydrolyzed silica, fumed silica, and optical fiber materials. Furthermore, magnesium-thermal reduction can be used to obtain high-purity silicon. Silicon products can be flexibly managed and switched based on market and regional needs.

[0033] In some embodiments, a liquid molten pool containing CaCl2 or KCl-NaCl-CaCl2 molten salt is added to a carbon-containing molten pool. High-aluminum solid waste, a carbonaceous reducing agent, and chlorine gas are then added to the molten pool for carbonization and chlorination to produce volatile aluminum trichloride. This solution utilizes a molten salt bath as the reaction medium, with the liquid serving as the continuous phase, significantly enhancing heat and mass transfer. The high-aluminum solid waste and carbonaceous reducing agent are submerged and sprayed into the molten pool for a rapid and efficient reaction, converting aluminum oxide to chloride within seconds.

[0034] Carbonaceous reducing agents must be high-strength, low-volatile, and low-ash to meet the requirements of carbonization and chlorination. This is because a high volatile content in the carbonaceous reducing agent, which also means a high hydrogen content, will combine with the chlorine in the chlorinating agent to form hydrogen chloride gas. This not only consumes more chlorine but also produces highly corrosive hydrogen chloride, requiring the disposal of additional hydrochloric acid in the exhaust gas treatment process. Therefore, high-quality calcined coke has traditionally been used as a carbonaceous reducing agent. However, high-quality calcined coke is an extremely expensive carbon material, often 5-6 times more expensive than conventional carbonaceous materials such as coal. Coal, conventional metallurgical coke, and lignite, which are readily available on the market, as well as recyclable waste plastics, waste rubber, biochar, and high-carbon organic solid wastes such as waste textile fibers, cannot be used in chlorination furnaces. This impacts the overall economic benefits of full-process industrialization projects led by carbonization and is detrimental to reducing greenhouse gas emissions throughout their lifecycle.

[0035] The present scheme uses any one or a combination of more than two of ordinary anthracite, bituminous coal, coke, semi-coke, waste plastics, waste rubber, biomass carbon, dry organic waste, and waste textiles as carbon-containing materials, and uses a molten salt bath similar to a liquid molten pool to pyrolyze, dehydrogenate, and remove ash from the carbon-containing materials, thereby effectively pyrolyzing conventional carbon materials and even carbon-containing solid waste to obtain high-quality pure carbon. Even if a small amount of molten salt component is mixed, it does not affect the direct application of the pure carbon to a chlorination furnace. Moreover, because the components in the molten salt bath are similar to those in the liquid molten pool, the presence of a small amount of molten salt component in the carbonaceous reducing agent does not affect the subsequent carbon addition chlorination.

[0036] Specifically, the carbon-containing materials and oxygen are added to the molten salt bath to pyrolyze and obtain decomposition gas and carbon particles. Oxygen and part of the carbon particles react to generate decomposition gas, and most of the carbon particles burst into carbonaceous particles suspended in the molten salt bath as a carbonaceous reducing agent.

[0037] In some embodiments, the molar amount of oxygen is 10% to 21% of the molar amount of the carbon-containing materials.

[0038] It should be noted that the carbon-containing materials are pyrolyzed in the high-temperature molten salt bath. Because the amount of oxygen introduced is relatively small, only 10-21% of the molar amount of fixed carbon, it is not enough to completely gasify. Incomplete oxidation generates heat to compensate for the heat absorption of organic matter pyrolysis. Therefore, the moisture in the carbon-containing materials evaporates, and most of the volatile matter is decomposed into carbon, hydrogen gas, CO gas, and methane gas. The oxygen introduced reacts with part of the carbon particles to generate CO gas. The chemical reaction can be simply expressed by the following formula.

[0039] .

[0040] Most of the carbon particles in the carbon-containing materials burst into carbonaceous particles in the molten salt bath. Because of the close density, the carbonaceous particles are suspended in the molten salt bath. At this time, the carbonaceous particles, as a carbonaceous reducing agent, have lost all moisture and most of the volatile matter. At the same time, most of the ash has also been separated and settled. Therefore, the hydrogen content of the carbonaceous reducing agent particles is extremely low. In the subsequent chlorination operation, when the hydrogen reacts with chlorine gas and aluminum-containing materials, hydrogen chloride gas is not generated.

[0041] In some embodiments, the residual heat in the decomposition gas is recovered and cooled and dusted to be used as a combustible gas, and the residual heat is recycled. Further, the combustible gas is used for gas power generation for subsequent electrolytic magnesium operation, and the residual heat is used to transfer sensible heat to oxygen by nitrogen to preheat the oxygen.

[0042] When the liquid melt pool only contains CaCl2 molten salt, the molten salt bath containing carbonaceous reducing agent is added into the liquid melt pool in a liquid injection manner. Specifically, the molten salt bath containing carbonaceous reducing agent can be added into the liquid melt pool in a hot molten state at a set flow rate.

[0043] In addition, as the carbon-chlorination process continues, the molten salt in the liquid melt pool gradually increases, and part of the carbon-poor molten salt in the liquid melt pool is recycled.

[0044] When the liquid melt pool contains KCl-NaCl-CaCl2 molten salt, the molten salt bath containing carbonaceous reducing agent is centrifuged to obtain the carbonaceous reducing agent, which is then added to the liquid melt pool.

[0045] It should be noted that because the melting point of the ternary molten salt in the molten salt bath is low, it is relatively easy to separate the solid and liquid by centrifuge. Therefore, part of the molten salt and the carbonaceous particles suspended therein can be periodically discharged and loaded into a high-temperature centrifuge to obtain carbonaceous particles as carbonaceous reducing agent by centrifugal separation. Although a small amount of KCl, NaCl and CaCl2 salt may adhere to the carbonaceous reducing agent at this time, the salt adhered to the carbonaceous reducing agent will not affect the subsequent carbon-chlorination reaction because the liquid melt pool also contains KCl-NaCl-CaCl2 molten salt during chlorination of the high-aluminum solid waste.

[0046] In some embodiments, the volatile matter residue of the carbonaceous reducing agent is only about 0.1%, and the ash residue is not more than 0.3%. Since the present scheme uses multiple carbon-containing materials, similar quality of carbonaceous reducing agent can be obtained, and the carbonaceous reducing agent obtained from unit mass of carbon-containing material is about 30-70%, but the remaining hydrogen-containing components are also converted into corresponding high-quality fuel gas for comprehensive utilization by production enterprises, or even for fuel gas power generation.

[0047] In some embodiments, the high-aluminum solid waste contains dry aluminum-containing solid waste: aluminum oxide and silicon oxide. In some embodiments, the high-aluminum solid waste includes high-aluminum fly ash, high-aluminum coal gangue, alumina by-product red mud, bauxite tailings, kaolin, three stones (sillimanite, cordierite, kyanite), etc.

[0048] In some embodiments, the temperature of the liquid melt pool is 900-1200°C, and the aluminum oxide in the high-aluminum solid waste is chlorinated to obtain volatile aluminum trichloride.

[0049] When the amount of carbonaceous reducing agent and chlorine gas reaches the full chlorination degree, the high-aluminum solid waste, the carbonaceous reducing agent, and the chlorine gas are added to the liquid melt pool to perform carbon-chlorination to obtain volatile aluminum trichloride and silicon tetrachloride: The reaction equation of carbon-chlorination is as follows:

[0050]

[0051]

[0052]

[0053]

[0054] .

[0055] When the liquid molten pool contains only CaCl2 molten salt, aluminum trichloride is often in the form of dimer in the volatile state. The temperature of aluminum trichloride condensing from gaseous phase to solid aluminum trichloride is about 170-190°C, while the boiling point of silicon tetrachloride is 58°C and the melting point is -68°C. Therefore, this scheme can use the different properties of volatile aluminum trichloride and silicon tetrachloride to separate the two.

[0056] In some embodiments, volatile aluminum trichloride flows through a primary condenser to be condensed to obtain condensed aluminum trichloride, and the condensation temperature of the primary condenser is 170-190°C. The volatile silicon tetrachloride that has not yet condensed flows through a secondary condenser to be condensed into liquid silicon tetrachloride. The residual gas generated in the carbon chlorination process is purified by absorbing hydrogen chloride and chlorine with aqueous solution and alkaline solution, and the remaining non-condensable gases such as CO, CO2, N2, Ar are discharged and used as fuel gas for comprehensive utilization.

[0057] In other embodiments, volatile aluminum trichloride and silicon tetrachloride are passed through a combined condenser pre-filled with liquid silicon tetrachloride, and are repeatedly sprayed with liquid silicon tetrachloride as a cooling medium to remove heat, thereby condensing to obtain a solid-liquid two-phase mixture. The solid-liquid two-phase mixture contains solid aluminum trichloride and newly condensed liquid silicon tetrachloride. After the solid-liquid two-phase mixture is heated to 60-80°C, the gaseous volatiles are condensed to obtain liquid silicon tetrachloride and residual solid aluminum trichloride, thereby achieving complete separation of the silicon and aluminum elements.

[0058] In some embodiments, magnesium in the metallic magnesium liquid is reduced to condensed aluminum trichloride to obtain a metallic aluminum alloy liquid and an anhydrous magnesium chloride melt, and the metallic aluminum alloy liquid is released to obtain metallic aluminum. The magnesium chloride is then returned to the electrolytic cell for electrolysis to obtain metallic magnesium liquid and chlorine gas. The reaction equation is as follows:

[0059] .

[0060] When the liquid molten pool is filled with KCl-NaCl-CaCl2 molten salt, the aluminum trichloride produced by carbonic chlorination will combine with potassium chloride and sodium chloride to form KAlCl4 and NaAlCl4 and volatilize. Due to the high volatilization temperature and the high condensation temperature, the aluminum trichloride can be condensed in a solid state by controlling the condensation temperature at 400-700°C. That is, when the amount of carbonaceous reducing agent and chlorine gas introduced reaches the degree of full chlorination, high-aluminum solid waste, carbonaceous reducing agent, and chlorine gas are added to the liquid molten pool filled with KCl-NaCl-CaCl2 molten salt for carbonic chlorination to obtain volatile potassium sodium tetrachlorochlorate and silicon tetrachloride. The volatile potassium sodium tetrachloroaluminate gas is cooled and condensed in a condenser at 400-700°C to obtain condensed potassium sodium tetrachloroaluminate. The silicon tetrachloride in the residual gas phase enters the next stage condenser and is condensed into liquid.

[0061] Furthermore, the metallic magnesium liquid and the reduced condensed aluminum trichloride are subjected to magnesium thermal reduction to obtain metallic aluminum, alkali metal potassium and sodium chlorides and anhydrous magnesium chloride. The alkali metal potassium and sodium chlorides are transferred to an electrolytic cell for electrolysis. The relevant reaction formula is as follows:

[0062] .

[0063] About the recycling of silicon tetrachloride: Volatile silicon tetrachloride is condensed to obtain liquid silicon tetrachloride, which is then exported, reduced by magnesium heat to a high-purity silicon semi-finished product, vapor deposited to high-grade silica, or hydrolyzed to ordinary silica.

[0064] In some embodiments, liquid silicon tetrachloride is exported to polysilicon companies and organosilicon companies for use as raw materials.

[0065] In some embodiments, liquid silicon tetrachloride is thermally reduced by magnesium to form a high-purity silicon semi-finished product. The liquid silicon tetrachloride is then injected into a metallic magnesium solution to undergo an exothermic reaction in which magnesium reduces silicon. The silicon tetrachloride is reduced by the metallic magnesium solution to form a deposited magnesium silicide solid and a magnesium chloride melt below the metallic magnesium solution. The magnesium silicide solid is then placed under high-temperature vacuum conditions to decompose and obtain high-purity silicon. The chemical reaction equation is as follows:

[0066] .

[0067] In some embodiments, liquid silicon tetrachloride is hydrolyzed into ordinary grade white carbon black, and the by-product hydrogen chloride is dissolved in water to form a hydrochloric acid solution, which is then absorbed by sodium hydroxide solution to form a brine solution, which is then electrolyzed to obtain hydrogen and chlorine. The hydrogen is used as fuel gas or for other purposes, and the chlorine is returned to the chlorination process for carbonization and chlorination. The by-product sodium hydroxide solution is then used to neutralize the hydrochloric acid solution, forming a self-circulating cycle. The reaction equation is as follows:

[0068]

[0069] .

[0070] In some embodiments, liquid silicon tetrachloride is vapor-deposited into high-grade silica. Hydrogen and oxygen are mixed with the vaporized silicon tetrachloride and ignited to obtain fumed silica. Hydrogen chloride gas is produced as a by-product. After cooling, it is also neutralized with an aqueous sodium hydroxide solution. The brine is then electrolyzed to form a self-circulating aqueous solution of hydrogen, chlorine, and sodium-hydroxyl ions. The reaction equation is as follows:

[0071]

[0072]

[0073] If the amount of carbonaceous reducing agent and chlorine introduced only reaches the level of selective chlorination, the high-aluminum solid waste, carbonaceous reducing agent, and chlorine are added to a liquid molten pool containing CaCl2 molten salt for carbochlorination to obtain volatile aluminum trichloride and solid silicon oxide, and the silicon oxide is collected. In this case, the amount of carbonaceous reducing agent and chlorine introduced is only sufficient to chlorinate the aluminum oxide, while the silicon oxide does not react or reacts very little. Since the aluminum oxide is chlorinated before the silicon oxide, the majority of the aluminum oxide is converted to aluminum chloride, while the majority of the silicon oxide remains unreacted and deposits at the bottom of the liquid molten pool. After being discharged and washed, the silicon oxide can be used for comprehensive utilization, such as as building materials, silicon fertilizer, or other siliceous raw materials.

[0074] As shown above, this solution uses various high-aluminum solid wastes as raw materials, employing a chlorination process to obtain 99.2% pure aluminum trichloride. Subsequently, magnesium thermal reduction is performed to produce aluminum alloys containing over 99% aluminum, with the remainder being alloying elements silicon and magnesium. This alloy meets the control standards for most common aluminum alloys, and the content of harmful elements is far below market standards. Measurements show an aluminum extraction rate exceeding 90%.

[0075] In the second aspect, the present invention provides a high-aluminum solid waste aluminum production device based on a magnesium-chlorine dual cycle, including: a carbonaceous reducing agent dehydrogenation and deashing device for producing a carbonaceous reducing agent, including a molten salt bath carbon material dehydrogenation furnace 901 with a built-in molten salt bath 902, a carbon material closed pressurized material tank 935 filled with carbon-containing material, and an oxygen lance 910 with the end immersed in the molten salt bath 902, wherein the molten salt bath 902 contains a molten salt of KCl-NaCl-CaCl2, the carbon material closed pressurized material tank 935 is passed through a closed pressurized gas, and the carbon-containing material is any one or a combination of two or more of ordinary anthracite, bituminous coal, coke, semi-coke, waste plastics, waste rubber, biomass carbon, dry organic waste, and waste textiles; A carbon-chlorination device for chlorinating high-aluminum solid waste includes a chlorination furnace 101 with a built-in liquid molten pool 102, a condensing device connected to the chlorination furnace 101, a gas cluster spray gun G and a solid powder cluster spray gun P with their ends immersed in the liquid molten pool 102, wherein the liquid molten pool 102 contains a molten salt of CaCl2 or a molten salt of KCl-NaCl-CaCl2, and the temperature of the liquid molten pool 102 is 900-1200°C. A magnesia thermal reduction device for magnesia thermal reduction of aluminum trichloride, comprising a magnesia thermal aluminum reduction furnace 401 filled with metallic magnesium liquid 402; A magnesium electrolytic cell 301 for producing magnesium metal liquid 402; The carbonaceous material and oxygen are added to the carbonaceous reducing agent dehydrogenation and deashing device to obtain a carbonaceous reducing agent, the carbonaceous reducing agent, high-aluminum solid waste and chlorine are added to the carbonization and chlorination device to obtain aluminum trichloride, the aluminum trichloride and metallic magnesium liquid are added to the magnesium thermal reduction device for magnesium thermal reduction to obtain metallic aluminum and anhydrous magnesium chloride melt, and the anhydrous magnesium chloride melt is added to the magnesium electrolysis cell 301 for electrolysis to obtain recycled metallic magnesium liquid and chlorine.

[0076] Regarding the carbonaceous reducing agent dehydrogenation and deashing device of this scheme Figure 1 As shown: Medium and low-quality carbon-containing materials and oxygen are added to the molten salt bath 902 for pyrolysis to generate decomposition gas and carbon particles. The oxygen and a portion of the carbon particles continue to react to generate decomposition gas, while most of the carbon particles explode into carbonaceous particles in the molten salt bath and are suspended in the molten salt bath as a carbonaceous reducing agent for subsequent use.

[0077] In some embodiments, nitrogen, argon or other gases are used as the closed pressurized gas in the carbon material sealed pressurized tank 935 , and the carbon-containing material is immersed in the molten salt bath 902 for pyrolysis.

[0078] In some implementations, the end of at least one carbon material spray gun 911 is immersed in the molten salt bath 902. At this time, carbon-containing materials such as ordinary anthracite, bituminous coal, coke, semi-coke, biomass carbon particles, etc. can be ground to millimeter level or finer, and then injected into the molten salt bath 902 through the immersed carbon material spray gun 911. At the same time, a small amount of oxygen is blown into the oxygen spray gun 910 to generate CO gas. The heat released by the incomplete carbon-oxygen reaction compensates for the endothermic effect of the pyrolysis of organic matter. The oxygen can be preheated to increase the physical heat introduced.

[0079] In some embodiments, the carbon material spray gun 911 and the oxygen spray gun 910 may be located at the top of the molten salt bath carbon material dehydrogenation furnace 901, or they may be symmetrically arranged obliquely downward on the outer wall of the molten salt bath carbon material dehydrogenation furnace 901, or only the oxygen spray gun 910 may be vertically inserted into the bottom of the molten salt bath 902. Regardless of the method, the ends of the carbon material spray gun 911 and the oxygen spray gun 910 are immersed in the molten salt bath 902 to immerse and spray the materials into the molten salt bath 902.

[0080] In some embodiments, the carbonaceous reducing agent dehydrogenation and deashing device includes a cooling dust collector 903 connected to the air duct of the molten salt bath carbon material dehydrogenation furnace 901. At this time, the decomposition gas generated by the pyrolysis of the carbon-containing material escapes from the air duct to the cooling dust collector 903, where the waste heat is recovered and the temperature is reduced and dust removed before being used as a combustible gas. The combustible gas can be further used to generate gas for subsequent electrolytic magnesium. The waste heat recovered in the cooling dust collector 903 can transfer the sensible heat to the oxygen to be entered into the oxygen lance 910 through nitrogen, thereby preheating the oxygen entering the furnace.

[0081] In some embodiments, the carbonaceous reducing agent dehydrogenation and deashing apparatus includes a slag pot 920 connected to the molten salt bath carbon material dehydrogenation furnace 901 via a slag discharge pipe 921. Silicon oxide and aluminum oxide deposited at the bottom of the molten salt bath carbon material dehydrogenation furnace 901 are collected into the slag pot 920 through the slag discharge pipe 921. It should be noted that the silicon oxide and aluminum oxide in the slag pot 920 are washed and desalted before being comprehensively utilized. If the aluminum content meets the required quality, it can also be injected into the liquid molten pool 102 via a spray gun for chlorination.

[0082] In some embodiments, when the liquid molten pool 102 contains molten salt of CaCl2, the carbonaceous reducing agent dehydrogenation and deashing device includes a molten salt discharge pipe 931 connected to the molten salt bath carbon material dehydrogenation furnace 901, and a carbon-containing slag liquid tank 981 connected to the molten salt discharge pipe 931. The carbon-containing slag liquid tank 981 is connected to the carbon-containing molten salt high-level liquid tank 135 located above the chlorination furnace 101. At this time, the molten salt and the carbonaceous reducing agent suspended therein in the molten salt bath carbon material dehydrogenation furnace 901 are regularly discharged into the carbon-containing slag liquid tank 981 through the molten salt discharge pipe 931. In a hot molten state, the carbon-containing slag liquid tank 981 is added to the carbon-containing molten salt high-level liquid tank 135 and enters the chlorination furnace 101 according to a predetermined flow rate. At this time, the carbonaceous reducing agent and molten salt are merged into the liquid molten pool 102.

[0083] In some embodiments, when the liquid molten pool 102 contains a molten salt of KCl-NaCl-CaCl2, a high-temperature centrifuge is used to separate the carbonaceous reducing agent and the liquid molten salt in the molten salt bath 902 by solid-liquid separation. This is because the ternary molten salt has a low melting point and is easier to separate into solids and liquids by a centrifuge. Figure 11 As shown, the molten salt bath carbon material dehydrogenation furnace 901 is connected to a high-temperature centrifuge 951, wherein a drainage hole is provided on the centrifuge inner cylinder 953 inside the high-temperature centrifuge 951, and the centrifuge inner cylinder 953 is placed inside the centrifuge outer cylinder 952. At this time, the molten salt solution added to the high-temperature centrifuge 951 remains in a liquid state and the centrifuge is started. The molten salt is ejected from the drainage hole and cools and adheres to the centrifuge outer cylinder 952. The carbonaceous reducing agent remains as a solid in the centrifuge inner cylinder 953. After the centrifuge is shut down, the carbonaceous reducing agent is removed, crushed, ground, and screened, and then sprayed into the chlorination furnace 101 through the material spray gun P. The cooled molten salt is scraped out of the centrifuge outer cylinder 952 and enters the molten salt return tank 936 while still hot, and then returned to the molten salt bath carbon material dehydrogenation furnace 901.

[0084] In some embodiments, the carbonaceous reducing agent dehydrogenation and deashing apparatus includes a molten salt return tank 936 connected to the molten salt bath carbon material dehydrogenation furnace 901. A portion of the carbon-depleted molten salt liquid in the chlorination furnace 101 is returned to the molten salt return tank 936. At this time, the chlorination furnace 101 is connected to the molten salt return tank 936 via the carbon-depleted molten salt low-level liquid tank 136 and a lifting mechanism.

[0085] Regarding the carbochlorination unit of this scheme: A cylindrical chlorination furnace 101 is filled with CaCl2 molten salt or KCl-NaCl-CaCl2 molten salt to form a liquid molten pool 102. Chlorine gas and CO gas are sprayed by immersion using a gas cluster spray gun G, and high-aluminum solid waste particles and carbonaceous reducing agent are sprayed by immersion using a solid powder cluster spray gun P, thereby completing carbon addition and chlorination in the liquid molten pool 102.

[0086] In some embodiments, the gas-focused spray lance G and the solid powder-focused spray lance P can be located at the top of the chlorination furnace 101, with their ends immersed in the liquid molten pool 102. Alternatively, they can be symmetrically arranged diagonally downward on the outer wall of the chlorination furnace 101 and inserted into the molten pool 101. The gas-focused spray lance G can also be independently inserted vertically upward into the bottom of the molten pool. Various combinations of side, top, and bottom spray lances are possible.

[0087] In some embodiments, the materials in the gas beam spray gun G and the solid powder beam spray gun P are as follows: Figure 3 As shown, it can be seen that the various material pipelines can be separately arranged in parallel within the corresponding cluster spray gun, or they can be arranged in a layered circular sleeve manner. In some embodiments, the gas cluster spray gun G and the solid powder cluster spray gun P are integrated into a large spray gun. The gas and material injected by the gas cluster spray gun G and the solid powder cluster spray gun P are shown in Table 1 below: Table 1 Gas and materials injected by jet-type injection of gas beam spray gun G and solid powder beam spray gun P

[0088] When the amount of carbonaceous reducing agent and chlorine introduced only reaches the selective chlorination level, that is, only enough for aluminum oxide to undergo chlorination reaction, while silicon oxide does not react or reacts very little, since aluminum oxide is chlorinated before silicon oxide, the vast majority of aluminum oxide is converted into aluminum chloride, while the vast majority of silicon oxide is unreacted. High-aluminum solid waste, carbonaceous reducing agent, and chlorine are added to a liquid molten salt bath containing CaCl2 for carbon chlorination to obtain volatile aluminum trichloride and silicon tetrachloride and solid silicon oxide, and the silicon oxide is collected. At this time, the bottom of the chlorination furnace 101 is connected to the solid slag tank 120 through the slag discharge port 121. The silicon oxide deposited at the bottom of the liquid molten pool 102 of the chlorination furnace 101 is regularly discharged through the slag discharge port 121 and placed in the solid slag tank 120. After washing, the silicon oxide can be comprehensively utilized, for example, as a building material, silicon fertilizer, or other siliceous raw materials.

[0089] When the amount of carbonaceous reducing agent and chlorine introduced reaches the degree of full chlorination, high-aluminum solid waste, carbonaceous reducing agent and chlorine are added to the liquid molten pool of molten salt containing CaCl2 for carbon chlorination to obtain volatile aluminum trichloride and silicon tetrachloride. At this time, the volatile aluminum trichloride is condensed and collected to obtain solid aluminum trichloride, and the volatile silicon tetrachloride is subsequently condensed and collected to obtain liquid silicon tetrachloride.

[0090] like Figure 2 As shown, in some embodiments, the condensing device includes a primary condenser 103 and a secondary condenser 104 connected in sequence, and the primary condenser 103 is connected to the chlorination furnace 101. When volatile silicon tetrachloride is generated in the liquid molten pool, aluminum trichloride enters the primary condenser 103 and is condensed into a solid, and the uncondensed silicon tetrachloride further enters the secondary condenser 104 and is condensed into a liquid.

[0091] Furthermore, the carbon addition and chlorination device includes a scrubbing tower 105 connected to the secondary condenser, wherein the scrubbing tower 105 is filled with an aqueous solution and an alkaline solution. The gas escaping from the liquid molten pool 102 passes through the scrubbing tower 105 and is absorbed by the aqueous solution and the alkaline solution for hydrogen chloride and chlorine and is purified. The remaining non-condensable gases such as CO, CO2, N2, Ar are discharged and used as fuel gas for comprehensive utilization.

[0092] like Figure 3 As shown, aluminum trichloride is often in the form of a dimer in the gas phase. The temperature at which it condenses from the gas phase to a solid is about 170-190°C, and it generally does not experience a liquid phase under low pressure. Silicon tetrachloride has a boiling point of 58°C and a melting point of -68°C. This solution uses a combined condensation method to obtain solid aluminum trichloride and liquid silicon tetrachloride. In some embodiments, the condensing device includes a high-melting-point chloride pre-condenser 149 and a combined condenser 150. Chlorides of calcium, magnesium, iron, manganese, etc. have high boiling points. After a small amount of volatilization, they will first condense in the high-melting-point chloride pre-condenser 149. The combined condenser 150 includes a condensing device pre-filled with low-temperature silicon tetrachloride liquid. The condensing device is placed in a constant-temperature cooler 152. The low-temperature medium enters the constant-temperature cooler 152 to take away heat and then flows out.

[0093] In some embodiments, cold brine enters the constant temperature cooler 152 from the cold brine inlet pipe 157 on the constant temperature cooler 152 and flows out from the cold brine outlet pipe 158 of the constant temperature cooler 152 to take away the heat released during the condensation process.

[0094] In some embodiments, the outlet of the condensing device is connected to the silicon tetrachloride liquid circulation pipe 154 and the silicon tetrachloride lifting pump 155. The liquid silicon tetrachloride in the condensing device is lifted by the pumping force of the silicon tetrachloride lifting pump 155 through the silicon tetrachloride liquid circulation pipe 154, pumped to the top of the merging condenser 150, and sprayed down after passing through the spray head 156. At the same time, the aluminum trichloride and silicon tetrachloride volatilized in the liquid molten pool 102 pass through the high melting point chloride pre-condenser 149 and enter the merging condenser 150 for combined condensation. After cooling, the aluminum trichloride is condensed into a solid, and the silicon tetrachloride is condensed into a liquid, forming a solid-liquid mixture 151 of solid aluminum chloride and liquid silicon tetrachloride located in the merging condenser 150.

[0095] In order to improve the cooling effect, a low-temperature heat exchanger 153 is provided above the aluminum chloride and silicon tetrachloride solid-liquid mixture 151 in the condensing equipment and in the silicon tetrachloride liquid circulation pipe 154.

[0096] like Figure 6As shown, in some embodiments, the outlet of the combined condenser 150 is connected to the distiller 160, and the distiller 160 is connected to the silicon tetrachloride condenser 170, wherein the outer side of the distiller 160 is wrapped with a heating jacket 162, and the heat flow medium enters the heating jacket 162 to heat the distiller 160 and then is discharged, and the heating temperature is 60-80°C, wherein the outer side of the silicon tetrachloride condenser 170 is wrapped with a second constant temperature cooler 172, and the condensed water enters the second constant temperature cooler 172 to cool the silicon tetrachloride condenser 170 and then is discharged.

[0097] In some embodiments, the distiller 160 includes a heating heat exchanger 163 for enhanced heating, and the silicon tetrachloride condenser 170 includes a cooling heat exchanger 173 .

[0098] In some embodiments, the hot fluid enters the heating jacket 162 through the heating medium inlet pipe 167 and flows out from the heating medium outlet pipe 168 , and the cold brine enters the second constant temperature cooler 172 through the second cold brine inlet pipe 177 and flows out from the second cold brine outlet pipe 178 .

[0099] Specifically, silicon tetrachloride solid-liquid mixture 151 enters distiller 160 and is heated, causing the silicon tetrachloride to volatilize and enter silicon tetrachloride condenser 170. Silicon tetrachloride condenser 170 is surrounded by a water jacket, serving as a second constant-temperature condenser 172. Cold brine, or other medium, delivered via second cold brine inlet pipe 177 removes the heat from the condensation of silicon tetrachloride within silicon tetrachloride condenser 170 and then flows out of cold brine outlet pipe 178. Residual aluminum trichloride in distiller 160 is mechanically discharged.

[0100] When only CaCl2 molten salt is used in the chlorination furnace 101, the device of the magnesium thermal reduction device is as follows: Figure 7 arrive Figure 10 As shown, Figure 7 arrive Figure 10 The figures represent the initial, middle, late and final stages of magnesium thermal reduction, respectively. Aluminum trichloride is added to a magnesium thermal reduction furnace 401 containing magnesium liquid 402. Magnesium reduces the aluminum trichloride to obtain aluminum liquid and anhydrous magnesium chloride melt 403. In the initial stage, the anhydrous magnesium chloride melt 403 is located below the magnesium liquid 402. As the reaction proceeds, the aluminum content in the metal liquid layer gradually increases, the density of the alloy liquid pool increases, and the alloy liquid mainly composed of aluminum gradually settles to the lower layer of molten magnesium chloride. After the reaction is completed, the aluminum liquid is regularly released as the product to the aluminum liquid tank 410. The upper magnesium chloride melt 403 is regularly released and returned to the magnesium electrolytic cell 301 as a raw material for electrolytic magnesium smelting. The magnesium liquid produced by the cathode of the magnesium electrolytic cell 301 is extracted from the magnesium electrolytic cell 301 and used in the magnesium liquid 402 in the magnesium thermal aluminum reduction furnace 401. The chlorine discharged from the anode is supplied to the chlorination furnace 101, realizing a dual circulation of magnesium and chlorine.

[0101] When CaCl2-NaCl-KCl molten salt is used in chlorination furnace 101, as shown in Figure 11 、 Figure 13 generated aluminum trichloride will combine with potassium chloride and sodium chloride to form KAlCl4 and NaAlCl4 and volatilize. Due to the high volatilization temperature, the condensation temperature is also high. By controlling the condensation temperature at 400-700°C, the solid-state condensation is accumulated in the potassium sodium tetrachloroaluminate condenser 148, which can be more completely separated from silicon tetrachloride, and high-purity aluminum chloride is obtained. Figures 13 to 16 The four states of the initial, middle, late, and end of the potassium sodium-containing molten salt magnesium reduction aluminum refining reaction are shown. Due to the excessive transfer of alkali metal potassium sodium chloride in the chlorination furnace 101 to the magnesium electrolysis tank 301, the composition balance is periodically performed by the exchange of calcium chloride melt between the chlorination furnace 101 and the magnesium electrolysis tank 301.

[0102] It should be noted that the molten aluminum discharged from the magnesium reduction furnace 401 generally contains a certain amount of metal magnesium and mixed with magnesium chloride, so in the hot molten state, the molten aluminum is loaded into the second high-temperature centrifuge 701, and the structure of the high-temperature centrifuge 701 is shown in Figure 23 .

[0103] The second centrifuge inner cylinder 703 inside the second high-temperature centrifuge 701 is provided with a liquid discharge hole. The melting point of the aluminum alloy containing a certain amount of magnesium is lower than that of magnesium chloride. The mixed melt is cooled by standing and heat exchange with the cylinder wall of the second centrifuge inner cylinder 703. At this time, the magnesium chloride solidifies, and the magnesium-containing aluminum alloy remains in a liquid state. Then start the centrifuge, the aluminum-magnesium alloy liquid is thrown out from the liquid discharge hole, and cooled to solid flakes on the second centrifuge outer cylinder 702. The magnesium chloride solid remains in the second centrifuge inner cylinder 703. After shutdown, the magnesium chloride solid is taken out and returned to the magnesium electrolysis tank 301 while hot. The magnesium-containing aluminum alloy can be further melted and purified or distilled to remove residual magnesium to obtain higher quality aluminum alloy.

[0104] Regarding the recycling of liquid silicon tetrachloride: When magnesium reduction of liquid silicon tetrachloride is used to produce high-purity silicon semi-finished products, as shown in Figures 19 to 22 , Figures 19 to 22The following table represents the four states of the magnesium thermal silicon refining reaction: initial, intermediate, final, and final. The second magnesium metal liquid 502 discharged from the magnesium electrolytic cell 301 is charged into the magnesium thermal silicon reduction furnace 501. The initial temperature of the magnesium metal liquid 402 is set above 650°C to keep the second magnesium metal liquid 502 molten. Liquid silicon tetrachloride is injected into the second magnesium metal liquid 502, causing an exothermic reaction in which magnesium reduces silicon. The magnesium thermal silicon reduction furnace 501 is equipped with a cooling device to remove heat. The liquid silicon tetrachloride is reduced by the magnesium metal liquid to form solid magnesium silicide Mg2Si, which is deposited at the bottom of the second magnesium metal liquid 502. The by-product, anhydrous molten magnesium chloride 503, sinks below the magnesium liquid. Residual magnesium liquid is periodically released, and the magnesium chloride melt is discharged into the magnesium chloride drain tank 510 and returned to the magnesium electrolytic cell 301 for electrolysis.

[0105] After the reaction is completed, the vacuum pump 550 is started to evacuate the vacuum, and a small amount of residual metallic magnesium and magnesium chloride are volatilized. Mg2Si decomposes under high-temperature vacuum conditions, and magnesium vapor escapes with the vacuum extraction. After the magnesium chloride is volatilized, it is first condensed into the magnesium chloride condenser 520, and then metallic magnesium is condensed and crystallized in the metallic magnesium condenser 530. The solid left in the furnace is high-purity silicon, whose purity is between industrial silicon and polysilicon, and can be used as an intermediate product of high-purity silicon used in polysilicon.

[0106] Those skilled in the art should understand that the technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0107] The above embodiments merely illustrate several embodiments of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A method for producing aluminum from high-aluminum solid waste based on magnesium-chlorine double circulation, characterized in that: include: Adding high-aluminum solid waste, a carbonaceous reducing agent, and chlorine gas to a liquid molten pool containing CaCl2 molten salt or KCl-NaCl-CaCl2 molten salt for carbonization and chlorination to obtain volatile aluminum trichloride, wherein the temperature of the liquid molten pool is 900-1200°C, wherein the carbonaceous reducing agent is obtained by adding a carbon-containing material and oxygen into a closed molten salt bath for pyrolysis and carbonization, the molten salt bath is filled with KCl-NaCl-CaCl2 molten salt, and the temperature of the KCl-NaCl-CaCl2 molten salt is 850-1050°C, wherein the carbon-containing material is any one or a combination of two or more of ordinary anthracite, bituminous coal, coke, semi-coke, waste plastics, waste rubber, biomass carbon, dry organic waste, and waste textiles; Condensing volatile aluminum trichloride to obtain condensed aluminum trichloride; The metallic magnesium liquid and condensed aluminum trichloride are subjected to magnesium thermal reduction to obtain metallic aluminum and anhydrous magnesium chloride melt; The magnesium chloride melt is placed in a magnesium electrolysis cell for electrolysis to obtain recycled chlorine gas and metallic magnesium liquid.

2. The method for producing aluminum from high-aluminum solid waste based on magnesium-chlorine double circulation according to claim 1, characterized in that: Carbon-containing materials and oxygen are added to a closed molten salt bath for pyrolysis to obtain decomposition gas and carbon particles. Oxygen reacts with some carbon particles to generate decomposition gas, and most of the carbon particles explode in the molten salt bath to form carbonaceous particles suspended in the molten salt bath as carbonaceous reducing agents. The molar amount of oxygen is 10% to 21% of the molar amount of the carbon-containing material.

3. The method for producing aluminum from high-aluminum solid waste based on magnesium-chlorine double circulation according to claim 1, characterized in that: When the liquid molten pool is only filled with CaCl2 molten salt, a molten salt bath containing a carbonaceous reducing agent is added to the liquid molten pool by liquid injection; when the liquid molten pool is filled with KCl-NaCl-CaCl2 molten salt, the molten salt bath containing the carbonaceous reducing agent is centrifuged to obtain a carbonaceous reducing agent, and the carbonaceous reducing agent is added to the liquid molten pool.

4. The method for producing aluminum from high-aluminum solid waste based on magnesium-chlorine double circulation according to claim 1, characterized in that: When the amount of carbonaceous reducing agent and chlorine introduced only reaches the level of selective chlorination, high-aluminum solid waste, carbonaceous reducing agent and chlorine are added to a liquid molten pool containing CaCl2 molten salt for carbon addition and chlorination to obtain volatile aluminum trichloride and solid silicon oxide, and the silicon oxide is collected.

5. The method for producing aluminum from high-aluminum solid waste based on magnesium-chlorine double circulation according to claim 1, characterized in that: When the amount of carbonaceous reducing agent and chlorine introduced reaches the degree of full chlorination, the high-aluminum solid waste, carbonaceous reducing agent and chlorine are added to a liquid molten pool containing CaCl2 molten salt for carbon addition and chlorination to obtain a mixed gas of volatile aluminum trichloride and silicon tetrachloride. The volatile aluminum trichloride flows through a primary condenser for condensation to obtain condensed aluminum trichloride. The condensation temperature of the primary condenser is 170-190°C. The volatile silicon tetrachloride that has not yet condensed enters a secondary condenser and is condensed into liquid silicon tetrachloride. Alternatively, the volatile aluminum trichloride and silicon tetrachloride flow through a combined condenser pre-filled with liquid silicon tetrachloride, and are repeatedly sprayed with liquid silicon tetrachloride as a cooling medium to remove heat, condensing to obtain a solid-liquid two-phase mixture. The solid-liquid two-phase mixture contains solid aluminum trichloride and newly condensed liquid silicon tetrachloride. The solid-liquid two-phase mixture is heated to 60-80°C and then the gaseous volatiles are condensed to obtain liquid silicon tetrachloride and residual solid aluminum trichloride.

6. The method for producing aluminum from high-aluminum solid waste based on magnesium-chlorine double circulation according to claim 1, characterized in that: When the amount of carbonaceous reducing agent and chlorine introduced reaches the degree of full chlorination, high-aluminum solid waste, carbonaceous reducing agent and chlorine are added to a liquid molten pool containing KCl-NaCl-CaCl2 molten salt for carbon addition and chlorination to obtain volatile potassium sodium tetrachlorochlorate and silicon tetrachloride. The volatile potassium sodium tetrachloroaluminate gas is cooled and condensed in a condenser at 400-700°C to obtain condensed potassium sodium tetrachloroaluminate. The silicon tetrachloride in the residual gas phase enters the next stage condenser and is condensed into liquid.

7. The method for producing aluminum from high-aluminum solid waste based on magnesium-chlorine double circulation according to any one of claims 5 or 6, characterized in that: Liquid silicon tetrachloride is exported, reduced by magnesium heat to high-purity silicon semi-finished products, vapor deposited to high-grade silica, or hydrolyzed to ordinary silica.

8. A high-aluminum solid waste aluminum production device based on magnesium-chlorine double circulation, characterized in that: include: A carbonaceous reducing agent dehydrogenation and deashing device for producing a carbonaceous reducing agent comprises a molten salt bath carbon material dehydrogenation furnace (901) with a built-in molten salt bath (902), a carbon material sealed pressurized material tank (935) containing a carbonaceous material, and an oxygen lance (910) with a terminal immersed in the molten salt bath (902), wherein the molten salt bath (902) contains a molten salt of KCl-NaCl-CaCl2, the carbon material sealed pressurized material tank (935) is passed through a closed pressurized gas, and the carbonaceous material is any one of ordinary anthracite, bituminous coal, coke, semi-coke, waste plastics, waste rubber, biomass carbon, dry organic waste, and waste textiles, or a combination of two or more thereof; A carbon-added chlorination device for chlorinating high-aluminum solid waste, comprising a chlorination furnace (101) with a built-in liquid molten pool (102), a condensing device connected to the chlorination furnace (101), a gas cluster spray gun G and a solid powder cluster spray gun P with the end immersed in the liquid molten pool (102), wherein the liquid molten pool (102) contains CaCl2 molten salt or KCl-NaCl-CaCl2 molten salt, and the temperature of the liquid molten pool (102) is 900-1200°C; A magnesia thermal reduction device for magnesia thermal reduction of aluminum trichloride, comprising a magnesia thermal aluminum reduction furnace (401) filled with metallic magnesium liquid (402); A magnesium electrolysis cell (301) for electrolyzing a magnesium metal solution (402); The carbonaceous material and oxygen are added to a carbonaceous reducing agent dehydrogenation and deashing device to obtain a carbonaceous reducing agent, the carbonaceous reducing agent, high-aluminum solid waste and chlorine are added to a carbonization and chlorination device to obtain aluminum trichloride, the aluminum trichloride and metallic magnesium liquid are added to a magnesium thermal reduction device for magnesium thermal reduction to obtain metallic aluminum and anhydrous magnesium chloride melt, and the anhydrous magnesium chloride melt is added to a magnesium electrolytic cell (301) for electrolysis to obtain recycled metallic magnesium liquid and chlorine.

9. The aluminum production device from high-aluminum solid waste based on magnesium-chlorine dual circulation according to claim 8, characterized in that: When the liquid molten pool (102) contains CaCl2 molten salt, the carbonaceous reducing agent dehydrogenation and deashing device includes a molten salt discharge pipe (931) connected to the molten salt bath carbon material dehydrogenation furnace (901), and a carbon-containing slag liquid tank (981) connected to the molten salt discharge pipe (931), and the carbon-containing slag liquid tank (981) is connected to the carbon-containing molten salt high-level liquid tank (135) located above the chlorination furnace (101); when the liquid molten pool (102) contains KCl-NaCl-CaCl2 molten salt, a high-temperature centrifuge is used to separate the carbonaceous reducing agent and the liquid molten salt in the molten salt bath (902) in a solid-liquid separation manner.

10. The aluminum production device from high-aluminum solid waste based on magnesium-chlorine dual circulation according to claim 8, characterized in that: The condensing device includes a primary condenser (103) and a secondary condenser (104) connected in sequence, and the primary condenser (103) is connected to the chlorination furnace (101). When volatile aluminum trichloride and silicon tetrachloride are generated in the liquid molten pool, the aluminum trichloride flows through the primary condenser (103) and is condensed into a solid, and the silicon tetrachloride that has not yet condensed further flows through the secondary condenser (104) and is condensed into a liquid; or, the condensing device includes a high melting point chloride precondenser (149) and a combined condenser (150), wherein the combined condenser (150) The invention comprises a condensing device filled with low-temperature silicon tetrachloride liquid, wherein the condensing device is placed in a constant temperature cooler (152). A low-temperature medium enters the constant temperature cooler (152) to take away heat and then flows out. Aluminum trichloride and silicon tetrachloride volatilized in the liquid molten pool (102) pass through a high-melting-point chloride pre-condenser (149) and enter a combined condenser (150) for combined condensation. After being cooled, the aluminum trichloride is condensed into a solid, and the silicon tetrachloride is condensed into a liquid, thereby forming a solid-liquid mixture (151) of solid aluminum chloride and liquid silicon tetrachloride located in the combined condenser (150).

11. The aluminum production device from high-aluminum solid waste based on magnesium-chlorine dual circulation according to claim 10, characterized in that: The outlet of the combined condenser (150) is connected to the distiller (160), and the distiller (160) is connected to the silicon tetrachloride condenser (170), wherein the outer side of the distiller (160) is wrapped with a heating jacket (162), and the heat flow medium enters the heating jacket (162) to heat the distiller (160) and then is discharged, and the heating temperature is 60-80°C, wherein the outer side of the silicon tetrachloride condenser (170) is wrapped with a second constant temperature cooler (172), and the condensed water enters the second constant temperature cooler (172) to cool the silicon tetrachloride condenser (170) and then is discharged.

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