A method for preparing high-purity anhydrous aluminum chloride

Abstract

This invention provides a method for preparing high-purity anhydrous aluminum chloride, belonging to the technical field of high-purity anhydrous aluminum chloride preparation. The invention uses alumina or aluminum-containing minerals as raw materials, chlorine as a chlorinating agent, carbon monoxide as a reducing agent, and oxygen as a heat regulator. The chlorination reaction is carried out in a stirred fluidized bed reactor. Gaseous aluminum chloride is continuously discharged as powder through a spiral-propelled condenser. The aluminum chloride is further refined and purified by removing iron from aluminum powder to obtain high-purity aluminum chloride with a mass fraction greater than 99.9%. Enriched rare and dispersed metal chlorides can be further separated and purified. High-temperature flue gas is used for heat exchange with the solid raw materials to improve heat utilization efficiency. The discharged carbon dioxide and chlorine are compressed and separated. The chlorine is returned to the chlorination section as a chlorine source, and the carbon dioxide reacts with biomass carbon to produce carbon monoxide, which is also returned to the chlorination section as a carbon source. This is a highly efficient, clean, and slag-free method for preparing anhydrous aluminum chloride.

Description

Technical Field

[0001] This invention belongs to the field of high-purity anhydrous aluminum chloride preparation technology, and relates to a method for preparing high-purity anhydrous aluminum chloride. Background Technology

[0002] Anhydrous aluminum chloride is a white granular or powdery substance with a strong hydrochloric acid odor; industrial grade is pale yellow. Anhydrous aluminum chloride is mainly used in petroleum cracking, synthetic rubber, synthetic dyes, fragrances, pharmaceuticals, and phthalocyanine-based organic pigments. In addition, anhydrous aluminum chloride is also frequently used in metal smelting, lubricant synthesis, pesticide manufacturing, and organoaluminum compounds.

[0003] Industrially, anhydrous aluminum chloride is typically produced by reacting aluminum ingots with chlorine gas in a sealed chlorination furnace, followed by sublimation and condensation. However, this method is costly, resulting in a persistently high price for anhydrous aluminum chloride.

[0004] Due to the problems associated with direct chlorination of aluminum ingots, the alumina powder method for preparing anhydrous aluminum chloride was subsequently developed, using alumina as a raw material for chlorination in an attempt to solve the cost problem of anhydrous aluminum chloride. Another method uses aluminum hydroxide as a raw material, first calcining aluminum hydroxide to prepare alumina, which is then chlorinated to produce anhydrous aluminum chloride. However, attention must be paid to the alumina crystal transformation problem, because when the calcination temperature of aluminum hydroxide exceeds 900℃, α-Al₂O₃ will form, which reduces the chlorination effect and is detrimental to subsequent chlorination reactions. Furthermore, the alumina chlorination reaction is exothermic; during the alumina chlorination process, temperature fluctuations in the reaction equipment are easily caused, increasing the operational difficulty and requiring timely heat removal to maintain the reaction equipment temperature. Patent US4289735A proposes adding corundum, quartz, silicon carbide, etc., to dilute the alumina content during the reaction process, while simultaneously increasing the operating gas rate to control internal temperature fluctuations. However, this method reduces equipment capacity, and the excessively high operating gas rate can carry away some unreacted alumina particles, reducing the purity of the anhydrous aluminum chloride product.

[0005] Patent CN111661861A discloses a method for producing high-purity anhydrous aluminum chloride from aluminum hydroxide. The aluminum hydroxide raw material is preheated by a cyclone separator before entering a fluidized bed, where it decomposes into highly reactive alumina at low temperature. This alumina is then cooled to form low-temperature alumina, which undergoes a chlorination reaction at low temperature. The chlorination flue gas is condensed after dust removal to recover anhydrous aluminum chloride, while the chlorination residue and dust are cooled and returned to the chlorination reactor. The condensed anhydrous aluminum chloride solid is then sublimated to separate it from non-volatile components. The volatilized high-purity anhydrous aluminum chloride gas is condensed to obtain high-purity anhydrous aluminum chloride solid. This patent discharges unreacted alumina through a guide pipe to a cooling fluidized bed, where it is cooled and returned to the chlorination reactor, thus removing heat and ensuring a relatively stable temperature within the reactor during the chlorination reaction. A scraper-type condenser is used to address the issue of anhydrous aluminum chloride adhesion. The patent also indicates that the obtained anhydrous aluminum chloride needs to be further purified by distillation to obtain high-purity anhydrous aluminum chloride.

[0006] In summary, existing methods for producing anhydrous aluminum chloride from alumina primarily utilize fluidized bed reactors. However, the temperature during the reaction process can easily deteriorate the fluidization state, reducing reaction efficiency and carrying away unreacted alumina particles, thus lowering the purity of the anhydrous aluminum chloride. While adding solid diluents reduces the impact of exothermic reactions to some extent, it also reduces reactor capacity and introduces impurities, requiring additional purification processes. Discharging unreacted alumina through a guide pipe to a cooling fluidized bed, and then returning it to the chlorination reactor to remove heat, can maintain a relatively stable reactor temperature, but it is prone to heat loss from the fluidized bed. Therefore, existing fluidized bed reactors for anhydrous aluminum chloride cannot fundamentally overcome the impact of exothermic reactions during alumina chlorination. Furthermore, due to the small particle size of the produced anhydrous aluminum chloride, it easily adheres to the condenser during natural condensation, and scraper-type collection devices cannot fundamentally solve the problem of anhydrous aluminum chloride adhesion. At the same time, existing technologies do not address the treatment of chlorination tail gas, and the remaining unreacted chlorine and generated carbon dioxide are not effectively utilized. In particular, under the "dual carbon" policy, controlling carbon dioxide emissions during the process is of great practical significance. Summary of the Invention

[0007] The existing method for preparing anhydrous aluminum chloride by chlorination of alumina has several drawbacks, including high cost, high price of aluminum chloride, reduced chlorination efficiency due to crystal transformation during oxidation, insufficient purity of anhydrous aluminum chloride products, and the inability of the fluidized bed reactor used to fundamentally overcome the influence of exothermic reaction during alumina chlorination. Therefore, it is urgent to develop a method for preparing aluminum chloride that is energy-efficient, has high chlorination utilization efficiency, zero emissions, clean production, and yields high-purity products.

[0008] To address the above problems, this invention provides a method for preparing high-purity anhydrous aluminum chloride, comprising the following steps:

[0009] Step 1: Grind and mix the aluminum-containing raw materials and supplementary biomass charcoal thoroughly and preheat;

[0010] Step 2: After preheating and mixing, the mixture is conveyed to a stirred fluidized bed, where supplementary chlorine and oxygen are introduced to carry out a chlorination reaction and generate high-temperature flue gas.

[0011] Step 3: Gaseous aluminum chloride in the high-temperature flue gas is continuously discharged in powder form through a spiral propeller condenser, yielding crude anhydrous aluminum chloride, crude silicon tetrachloride, and chlorine-containing flue gas;

[0012] Step 4: Crude anhydrous aluminum chloride is further refined and purified by reducing distillation to obtain high-purity aluminum chloride; crude silicon tetrachloride is obtained by distillation to obtain high-purity silicon tetrachloride, and the enriched rare and dispersed metal chlorides can be further separated and purified.

[0013] In step 1, the aluminum-containing raw material is one of the following: alumina or gibbsite, boehmite, diaspore, kaolin, illite, pyrophyllite, red mud, fly ash, coal gangue, and coal gasification slag.

[0014] The reducing agent is carbon monoxide; the mass ratio of carbon in carbon monoxide to aluminum-containing raw material is (0.1-3):1, and the particle size ratio of aluminum-containing raw material to supplementary biomass carbon is 1:(1-8); carbon monoxide is used as the carbon source, and biomass carbon is used as the supplementary carbon source to avoid the use of fossil carbon or petroleum coke, thereby avoiding the generation of sulfides and nitrogen oxides in the subsequent flue gas.

[0015] In step 2, the stirred fluidized bed is a type of boiling bed or suspended fluidized bed, consisting of multiple parts including a discharge airlock, an air inlet, a fluidized bed furnace body, a side stirring feed, a side stirring paddle, a top stirring paddle, a flue gas channel, a flue gas outlet, and a stirring motor. The discharge airlock, air inlet, and flue gas outlet are connected to the fluidized bed furnace body via flanges. The discharge airlock ensures unidirectional discharge of solid residue. A top stirring paddle is installed on the top of the furnace body, rotating at 40-150 rpm driven by the stirring motor. The top stirring uses centrifugal force to separate fine particles back into the bed, preventing small particles from escaping. The side stirring paddle has a hollow internal structure for conveying solid raw materials into the fluidized bed. The angle between the stirring paddle shaft and the furnace body is continuously adjustable from 0° to 90°, and the stirring speed is 20-150 rpm. Compared with traditional fluidized beds, the occurrence rate of large bubbles in the bed is reduced by more than 60%, the system heat transfer efficiency is increased by more than 30%, and the dust carryover rate is reduced to below 2%.

[0016] The chlorination reaction is carried out at a temperature of 300–1100°C, with an oxygen to chlorine ratio of (0.01–0.3):1, and a reaction time of 1–120 min. The chlorination efficiency of alumina in the chlorination reaction is greater than 93%.

[0017] The oxygen introduced is oxygen-enriched air with an oxygen content of 25% to 100%. The purpose is twofold: first, to reduce the amount of flue gas, and second, to ensure the thermal balance of the stirred fluidized bed.

[0018] In step 3, the spiral propulsion condenser consists of multiple parts, including a stirring motor, a spiral propulsion agitator, a flue gas inlet, a discharge airlock, a flue gas outlet, and a tank. The spiral propulsion agitator, flue gas outlet, discharge airlock, and flue gas outlet are connected to the tank flange. The shaft of the spiral propulsion agitator is hollow. The remaining flue gas after condensation is discharged through the axial flue gas outlet. The spiral propulsion agitator rotates under the action of the stirring motor. The propulsion speed of the spiral propulsion agitator is 1-50 rpm, which pushes the condensed product to move towards the bottom discharge airlock. The discharge airlock ensures that the condensed product is discharged in one direction, preventing the anhydrous chloride from adhering to the wall surface during condensation, and ensuring the continuous discharge and packaging of chloride powder or liquid.

[0019] When the helical propulsion condenser uses one of the following aluminum-containing raw materials: gibbsite (trihydrate), boehmite (monohydrate), diaspore (monohydrate), kaolin, illite, pyrophyllite, red mud, fly ash, coal gangue, or coal gasification slag, a three-stage helical propulsion condenser is required. The first stage controls the temperature range of 250–300℃ to obtain crude ferric chloride; the second stage controls the temperature of 150–180℃ to obtain crude aluminum chloride; and the third stage controls the temperature of 0–50℃ to obtain crude silicon tetrachloride. When alumina is used as the aluminum-containing raw material, a single-stage helical propulsion condenser is used, controlling the temperature of 150–180℃ to obtain crude aluminum chloride. By using the helical propulsion condenser, continuous discharge and packaging of chloride powder or liquid are ensured, the condensation recovery efficiency of anhydrous chloride is above 99%, and the water absorption rate of anhydrous chloride is less than 0.1%.

[0020] By using the high-temperature flue gas generated by the fluidized bed for heat exchange of solid raw materials, the heat utilization efficiency was improved by 60%.

[0021] In step 3, the chlorine-containing flue gas is compressed and separated to generate chlorine, carbon dioxide and biomass carbon, and solid residue. The chlorine is returned to the chlorination reaction stage as a chlorine source; the carbon dioxide reacts with the biomass carbon to produce carbon monoxide, which is returned to the chlorination stage as a carbon source; and the remaining solid residue is used as raw material for kaolin or silicon fertilizer.

[0022] The carbon dioxide and biomass carbon react in a closed rotary roasting furnace to produce carbon monoxide. The roasting temperature is 700-1100℃ and the roasting time is 10-120 min. After roasting, the carbon residue in the carbon-containing raw material is less than 0.06 wt%, and the mass fraction of carbon monoxide in the obtained flue gas is greater than 75%.

[0023] In step 4, the mass fraction of high-purity silicon tetrachloride is 99.9% or higher.

[0024] The present invention provides a method for preparing high-purity anhydrous aluminum chloride, which, compared with the prior art, has the following advantages:

[0025] (1) Low energy consumption and high chlorination utilization efficiency. The heat released by the chlorination and carbon oxidation reactions is used to maintain the reaction operation without additional heating, which solves the problem of fluidization deterioration caused by temperature fluctuations in existing fluidized bed reactors and improves the chlorination rate. Biomass carbon is preferred as the carbon source during the chlorination process. It has low impurity content, reduces flue gas volume, has a rich pore structure and a large specific surface area, and can effectively adsorb chlorine molecules, promote the dissociation of chlorine molecules into more active chlorine atoms, promote the chlorination reaction, and achieve a chlorination efficiency of more than 90%.

[0026] (2) The fluidized bed (including boiling bed and suspended fluidized bed) used is a stirred fluidized bed. The internal structure of the side stirring shaft of the fluidized bed is hollow, which can transport solid particulate materials. The stirring paddle and the stirring shaft are connected to ensure that solid particles enter the fluidized bed from the bottom of the stirring paddle. The stirring shaft at the top of the fluidized bed can use centrifugal force to separate fine particles back into the bed to prevent particles from escaping. The rotation speed is 40-150 rpm, and the dust rate is reduced to below 2%. The side stirring paddle has a hollow internal structure to transport solid raw materials into the fluidized bed. The occurrence rate of large bubbles in the bed is reduced to below 60%, and the heat transfer efficiency of the system is increased to above 30%.

[0027] (3) High purity of anhydrous chloride products. The condenser for gaseous chloride is a screw-propelled condenser. The screw-propelled agitator moves the chloride through the discharge airlock at a speed of 1-50 rpm, preventing the anhydrous chloride from adhering to the wall surface. This ensures the continuous discharge and packaging of chloride powder or liquid. The condensation recovery efficiency of anhydrous chloride is greater than 99%, and the water absorption rate of anhydrous chloride is less than 0.1%.

[0028] (4) Zero emissions, clean production, and high added value of products. High-temperature flue gas is used for heat exchange of solid raw materials, which improves the heat utilization efficiency by 60%. The discharged carbon dioxide and chlorine are compressed and separated. The chlorine is returned to the chlorination section as a chlorine source. The carbon dioxide reacts with biomass carbon to produce carbon monoxide, which is returned to the chlorination section as a carbon source. This is a highly efficient, clean, and slag-free method for preparing anhydrous aluminum chloride. Attached Figure Description

[0029] Figure 1 Flowchart for the preparation of anhydrous aluminum chloride.

[0030] Figure 2 A schematic diagram of a stirred fluidized bed.

[0031] Figure 3 Schematic diagram of a spiral propulsion condenser device.

[0032] Among them, 1-discharge airlock, 2-air inlet, 3-fluidized bed furnace body, 4-side stirring feed, 5-side stirring paddle, 6-top stirring paddle, 7-fluidized gas passage, 8-fluidized gas outlet, 9-stirring motor; 10-stirring motor; 11-spiral propeller stirring paddle; 12-fluidized gas inlet; 13-airlock; 14-tank body; 15-fluidized gas outlet Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0034] The alumina used in the examples has the following main components: Al2O3-98.6%, SiO2-0.01%, Fe2O3-0.02%, and Na2O-0.5%.

[0035] The bauxite used in the example has the following main components: Al2O3 63.85%, SiO2 12.84%, TiO2 2.93%, Fe2O3 3.64%, Ga2O3-40ppm, Sc2O3-30ppm, Li2O-120ppm, and the remainder are trace elements.

[0036] The red mud used in the examples mainly consists of Al2O3-23.85%, SiO2-19.84%, TiO2-2.93%, Fe2O3-6.64%, Ga2O3-30ppm, Sc2O3-80ppm, Li2O-60ppm, with the remainder being impurities.

[0037] The aluminum ash used in the examples mainly consists of Al-45.3%, MgO-10%, F-2.3%, Cl-15.3%, with the remainder being impurities.

[0038] The fly ash used in the examples mainly consists of Al2O3-47.8%, SiO2-42.3%, MgO-1.21%, Fe2O3-3.51%, TiO2-2.3%, Ga2O3-80ppm, Sc2O3-30ppm, Li2O-400ppm, GeO2-32ppm, with the remainder being impurities.

[0039] The main components of the coal gangue used in the examples are shown in the table below: C-14.9%, O-48.3%, Al-11%, Si-19.3%, K-0.75%, Ca-1.07%, Fe-2.29%, with the balance being impurities.

[0040] The main components of the coal gasification slag used in the examples are Al2O3-8.72%, SiO2-35.24%, MgO-1.54%, Fe2O3-5.73%, with the remainder being impurities.

[0041] The biomass carbon used in the examples has a carbon content of 90.5%, with the remainder being volatile matter and other impurities;

[0042] The preparation process of anhydrous aluminum chloride in the examples is as follows: Figure 1 As shown, the stirred fluidized bed and the spiral propulsion condenser devices are respectively as follows: Figure 2 , 3 As shown;

[0043] The production process described in this invention is not limited to using this type of raw material; any raw material with aluminum as its main component can be produced using this technology.

[0044] Example 1

[0045] A method for preparing high-purity anhydrous aluminum chloride mainly includes the following steps:

[0046] (1) Using alumina as raw material, carbon monoxide as carbon source, and biomass carbon as supplementary carbon source, the mass ratio of carbon to alumina in carbon monoxide and biomass carbon is 0.1:1, and the particle size ratio of alumina to supplementary biomass carbon is 1:5.

[0047] (2) The uniformly mixed raw materials are added to the stirred fluidized bed through a side-mounted stirring shaft. The chlorination process is carried out at a reaction temperature of 500℃ for 120 min, with an oxygen to chlorine ratio of 0.05:1. The chlorination reaction is as follows:

[0048] Al2O3+1.5C+3Cl2=2AlCl3+1.5CO2

[0049] Al₂O₃ + 3C + 3Cl₂ = 2AlCl₃ + 3CO

[0050] (3) Stirred fluidized bed, with the side stirring paddle shaft and the furnace body at an angle of 45°, stirring speed of 50 rpm, and top stirring paddle speed of 40 rpm. Compared with traditional fluidized bed, the large bubble rate is reduced by 65%, the heat transfer efficiency is increased by 30%, and the dust carrying rate is reduced by 1%.

[0051] (4) The condenser for gaseous aluminum chloride is a spiral propulsion condenser. The temperature is controlled within the range of 150℃. The spiral propulsion condenser and the spiral propulsion agitator are used to propel the aluminum chloride through the discharge airlock at a speed of 10 rpm. The aluminum chloride is then discharged and sealed. The separation efficiency between the flue gas and anhydrous aluminum chloride is 99%, and the moisture content of the resulting anhydrous aluminum chloride is 0.1%.

[0052] (5) The discharged carbon dioxide and chlorine are compressed and separated. The chlorine is returned to the chlorination section as a chlorine source, and the carbon dioxide reacts with biomass carbon to produce carbon monoxide, which is returned to the chlorination section as a carbon source. Specifically, carbon dioxide reacts with carbon-containing raw materials in a closed rotary roasting furnace to produce carbon monoxide. The roasting temperature is 700℃, the roasting time is 10 min, the residual carbon content in the carbon-containing raw materials after roasting is 0.05 wt%, and the mass fraction of carbon monoxide in the resulting flue gas is 80%.

[0053] After treatment by this method, the chlorination efficiency of alumina is 95%; after separation and purification of the gas phase product, anhydrous aluminum chloride with a mass fraction of 99.9% is obtained.

[0054] Example 2

[0055] A method for preparing high-purity anhydrous aluminum chloride mainly includes the following steps:

[0056] (1) Using bauxite as raw material, carbon monoxide as carbon source, and biomass carbon as supplementary carbon source, the mass ratio of carbon to bauxite in carbon monoxide and biomass carbon is 0.6:1, and the particle size ratio of bauxite to supplementary biomass carbon is 1:6.

[0057] (2) The uniformly mixed raw materials are added to the stirred fluidized bed through the side stirring shaft. The chlorination process is carried out at a reaction temperature of 1000℃ and a reaction time of 90min, with an oxygen to chlorine ratio of 0.04:1.

[0058] The chlorination process is as follows:

[0059] Al2O3+1.5C+3Cl2=2AlCl3+1.5CO2

[0060] Al₂O₃ + 3C + 3Cl₂ = 2AlCl₃ + 3CO

[0061] SiO₂ + C + 2Cl₂ = SiCl₄ + CO₂

[0062] SiO₂ + 2C + 2Cl₂ = SiCl₄ + 2CO

[0063] TiO₂ + C + 2Cl₂ = TiCl₄ + CO₂

[0064] TiO₂ + 2C + 2Cl₂ = TiCl₄ + 2CO

[0065] CaO + 0.5C + Cl₂ = CaCl₂ + CO₂

[0066] CaO + C + Cl₂ = CaCl₂ + CO

[0067] Fe2O3+1.5C+3Cl2=2FeCl3+1.5CO2

[0068] Fe₂O₃ + 3C + 3Cl₂ = 2FeCl₃ + 3CO

[0069] Sc2O3+1.5C+3Cl2=2ScCl3+1.5CO2

[0070] Sc₂O₃ + 3C + 3Cl₂ = 2ScCl₃ + 3CO

[0071] Ga2O3+1.5C+3Cl2=2GaCl3+1.5CO2

[0072] Ga₂O₃ + 3C + 3Cl₂ = 2GaCl₃ + 3CO

[0073] Na₂O + 0.5C + Cl₂ = 2NaCl + 0.5CO₂

[0074] Na₂O + C + Cl₂ = 2NaCl + CO₂

[0075] Li₂O + 0.5C + Cl₂ = 2LiCl + 0.5CO₂

[0076] Li₂O + C + Cl₂ = 2LiCl + CO

[0077] (3) Stirred fluidized bed, with the side stirring paddle shaft and the furnace body at an angle of 40°, stirring speed of 80 rpm, and top stirring paddle speed of 100 rpm. Compared with traditional fluidized bed, the large bubble rate is reduced by 70%, the heat transfer efficiency is increased by 35%, and the dust carrying rate is reduced by 1.5%.

[0078] (4) The gas phase chlorination product is processed by a three-stage spiral propulsion condenser. The spiral propulsion agitator is driven at a speed of 50 rpm, which pushes the condensed product out through the discharge airlock. First, the temperature is controlled at 300℃ to obtain crude ferric chloride product. Then, the temperature is controlled at 180℃ to obtain crude aluminum chloride. Finally, the temperature is controlled at 50℃ to obtain crude silicon tetrachloride. Through the spiral propulsion condenser, the separation efficiency of flue gas and chlorination product is 99%, and the water content of the obtained chloride is 0.1%.

[0079] (5) Crude aluminum chloride is de-ironized by aluminum powder to obtain high-purity aluminum chloride with a mass fraction greater than 99.9%, and silicon tetrachloride is distilled to obtain high-purity silicon tetrachloride with a mass fraction greater than 99.9%. The enriched rare and dispersed metal chlorides can be further separated and purified.

[0080] The gas-phase product purification and oxidation process is as follows:

[0081] Al + 0.75TiCl₄ = AlCl₃ + 0.75Ti

[0082] Al + GaCl3 = AlCl3 + Ga

[0083] Al + FeCl3 = AlCl3 + Fe

[0084] (6) The discharged carbon dioxide and chlorine are compressed and separated. The chlorine is returned to the chlorination section as a chlorine source, and the carbon dioxide reacts with biomass carbon to produce carbon monoxide, which is returned to the chlorination section as a carbon source. Among them, carbon dioxide reacts with carbon-containing raw materials in a closed rotary roasting furnace to produce carbon monoxide. The roasting temperature is 1100℃ and the roasting time is 120min. After roasting, the carbon residue in the carbon-containing raw materials is 0.04wt%, and the mass fraction of carbon monoxide in the obtained flue gas is 80%.

[0085] After processing by this method, the chlorination efficiency of aluminum, silicon, and rare metals in bauxite is 97%. After separation and purification of the gas phase products, anhydrous aluminum chloride with a mass fraction of 99.9% is obtained. Silicon tetrachloride is distilled to obtain high-purity silicon tetrachloride with a mass fraction of 99.9%. The enriched rare metal chlorides can be further separated and purified.

[0086] Example 3

[0087] A method for preparing high-purity anhydrous aluminum chloride mainly includes the following steps:

[0088] (1) Using red mud as raw material, carbon monoxide as carbon source, and biomass carbon as supplementary carbon source, the mass ratio of carbon in carbon monoxide and biomass carbon to red mud is 2:1, and the particle size ratio of red mud to supplementary biomass carbon is 1:7.

[0089] (2) The uniformly mixed raw materials are added to the stirred fluidized bed through a side stirring shaft. The chlorination process is carried out at a reaction temperature of 900℃ for 80 min, with an oxygen to chlorine ratio of 0.08:1. The chlorination process reaction is as follows:

[0090] Al2O3+1.5C+3Cl2=2AlCl3+1.5CO2

[0091] Al₂O₃ + 3C + 3Cl₂ = 2AlCl₃ + 3CO

[0092] SiO₂ + C + 2Cl₂ = SiCl₄ + CO₂

[0093] SiO₂ + 2C + 2Cl₂ = SiCl₄ + 2CO

[0094] TiO₂ + C + 2Cl₂ = TiCl₄ + CO₂

[0095] TiO₂ + 2C + 2Cl₂ = TiCl₄ + 2CO

[0096] CaO + 0.5C + Cl₂ = CaCl₂ + CO₂

[0097] CaO + C + Cl₂ = CaCl₂ + CO

[0098] Fe2O3+1.5C+3Cl2=2FeCl3+1.5CO2

[0099] Fe₂O₃ + 3C + 3Cl₂ = 2FeCl₃ + 3CO

[0100] Sc2O3+1.5C+3Cl2=2ScCl3+1.5CO2

[0101] Sc₂O₃ + 3C + 3Cl₂ = 2ScCl₃ + 3CO

[0102] Ga2O3+1.5C+3Cl2=2GaCl3+1.5CO2

[0103] Ga₂O₃ + 3C + 3Cl₂ = 2GaCl₃ + 3CO

[0104] Na₂O + 0.5C + Cl₂ = 2NaCl + 0.5CO₂

[0105] Na₂O + C + Cl₂ = 2NaCl + CO₂

[0106] Li₂O + 0.5C + Cl₂ = 2LiCl + 0.5CO₂

[0107] Li₂O + C + Cl₂ = 2LiCl + CO

[0108] (3) Stirred fluidized bed, with the side stirring paddle shaft and the furnace body at an angle of 60°, stirring speed of 100 rpm, and top stirring paddle speed of 150 rpm. Compared with traditional fluidized bed, the large bubble rate is reduced by 75%, the heat transfer efficiency is increased by 40%, and the dust carrying rate is reduced by 0.5%.

[0109] (4) The gas phase chloride is produced by a three-stage spiral propulsion condenser. The spiral propulsion agitator is driven at a speed of 50 rpm, which pushes the chloride out through the discharge airlock. The first stage is controlled at 280℃ to obtain crude ferric chloride, the second stage is controlled at 160℃ to obtain crude aluminum chloride, and the third stage is controlled at 0℃ to obtain crude silicon tetrachloride. The separation efficiency of flue gas and chloride through the spiral propulsion condenser is 99%, and the water content of the obtained chloride is 0.1%.

[0110] (5) Aluminum chloride is de-ironized by aluminum powder to obtain high-purity aluminum chloride with a mass fraction of 99.9%, and silicon tetrachloride is distilled to obtain high-purity silicon tetrachloride with a mass fraction of 99.9%. The enriched rare and dispersed metal chlorides can be further separated and purified.

[0111] The gas-phase product purification and oxidation process is as follows:

[0112] Al + 0.75TiCl₄ = AlCl₃ + 0.75Ti

[0113] Al + GaCl3 = AlCl3 + Ga

[0114] Al + FeCl3 = AlCl3 + Fe

[0115] (6) The discharged carbon dioxide and chlorine are compressed and separated. The chlorine is returned to the chlorination section as a chlorine source, and the carbon dioxide reacts with biomass carbon to produce carbon monoxide, which is returned to the chlorination section as a carbon source. Among them, carbon dioxide reacts with carbon-containing raw materials in a closed rotary roasting furnace to produce carbon monoxide. The roasting temperature is 1000℃ and the roasting time is 100min. After roasting, the carbon residue in the carbon-containing raw materials is 0.03wt%, and the mass fraction of carbon monoxide in the obtained flue gas is 85%.

[0116] After treatment by this method, the chlorination efficiency of alumina is 95%; after separation and purification of the gas phase product, anhydrous aluminum chloride with a mass fraction of 99.9% is obtained; silicon tetrachloride is distilled to obtain high-purity silicon tetrachloride with a mass fraction of 99.9%, and the enriched rare and dispersed metal chlorides can be further separated and purified.

[0117] Example 4

[0118] A method for preparing high-purity anhydrous aluminum chloride mainly includes the following steps:

[0119] (1) Using aluminum ash as raw material, carbon monoxide as carbon source, and biomass carbon as supplementary carbon source, the mass ratio of carbon to aluminum ash in carbon monoxide and biomass carbon is 3:1, and the particle size ratio of aluminum ash to supplementary biomass carbon is 1:8.

[0120] (2) The uniformly mixed raw materials are added to the stirred fluidized bed through a side-mounted stirring shaft. The chlorination process is carried out at a reaction temperature of 450℃ for 60 min, with an oxygen to chlorine ratio of 0.1:1. The chlorination reaction process is as follows:

[0121] Aluminum

[0122] 2Al + 3Cl₂ = 2AlCl₃

[0123] Alumina

[0124] Al₂O₃ + 3C + 3Cl₂ = 2AlCl₃ + 3CO or Al₂O₃ + 1.5C + 3Cl₂ = 2AlCl₃ + 1.5CO₂

[0125] Aluminum nitride

[0126] 2AlN + 3Cl2 = 2AlCl3 + N2

[0127] Spinel (taking aluminum-magnesium spinel as an example)

[0128] MgAl₂O₄ + 4Cl₂ + 4C = MgCl₂ + 2AlCl₃ + 4CO or MgAl₂O₄ + 4Cl₂ + 2C = MgCl₂ + 2AlCl₃ + 2CO₂

[0129] silicon dioxide

[0130] SiO₂ + 2Cl₂ + 2C = SiCl₄ + 2CO or SiO₂ + 2Cl₂ + C = SiCl₄ + CO₂

[0131] (3) Stirred fluidized bed with a side stirring paddle shaft at an angle of 35° to the furnace body, a stirring speed of 150 rpm, and a top stirring paddle speed of 60 rpm. Compared with the traditional fluidized bed, the large bubble rate is reduced by 70%, the heat transfer efficiency is increased by 42%, and the dust carrying rate is reduced by 1.0%.

[0132] (4) The gas phase chlorination product is processed by a multi-stage spiral propulsion condenser. The spiral propulsion agitator is driven at a speed of 100 rpm, which pushes the condensed product out through the discharge airlock. The first stage is controlled at 250℃ to obtain crude ferric chloride, the second stage is controlled at 180℃ to obtain crude aluminum chloride, and the third stage is controlled at 40℃ to obtain crude silicon tetrachloride. Through the spiral propulsion condenser, the separation efficiency of flue gas and chloride is 99%, and the water content of the obtained chloride is 0.1%.

[0133] (5) Aluminum chloride is further refined and purified by removing iron with aluminum powder to obtain high-purity aluminum chloride with a mass fraction greater than 99.9%. Silicon tetrachloride is obtained by distillation to obtain high-purity silicon tetrachloride with a mass fraction greater than 99.9%. The enriched rare and dispersed metal chlorides can be further separated and purified.

[0134] The gas-phase product purification and oxidation process is as follows:

[0135] Al + 0.75TiCl₄ = AlCl₃ + 0.75Ti

[0136] Al + GaCl3 = AlCl3 + Ga

[0137] Al + FeCl3 = AlCl3 + Fe

[0138] (6) The discharged carbon dioxide and chlorine are compressed and separated. The chlorine is returned to the chlorination section as a chlorine source, and the carbon dioxide reacts with biomass carbon to produce carbon monoxide, which is returned to the chlorination section as a carbon source. Specifically, carbon dioxide reacts with carbon-containing raw materials in a closed rotary roasting furnace to produce carbon monoxide. The roasting temperature is 800℃, the roasting time is 80 min, the residual carbon content in the carbon-containing raw materials after roasting is 0.04 wt%, and the mass fraction of carbon monoxide in the resulting flue gas is 85%.

[0139] After treatment by this method, the chlorination efficiency of alumina is 95%; after separation and purification of the gas phase product, anhydrous aluminum chloride with a mass fraction of 99.9% is obtained; silicon tetrachloride is distilled to obtain high-purity silicon tetrachloride with a mass fraction of 99.9%, and the enriched rare and dispersed metal chlorides can be further separated and purified.

[0140] Example 5

[0141] A method for preparing high-purity anhydrous aluminum chloride mainly includes the following steps:

[0142] (1) Using fly ash as raw material, carbon monoxide as carbon source, and biomass carbon as supplementary carbon source, the mass ratio of carbon to fly ash in carbon monoxide and biomass carbon is 0.5:1, and the particle size ratio of fly ash to supplementary biomass carbon is 1:1.

[0143] The chlorination reaction of fly ash is as follows

[0144] Al6Si2O 13 +13C + 13Cl2 = 6AlCl3 + 2SiCl4 + 13CO or Al6Si2O 13 +6.5C+13Cl2=6AlCl3+2SiCl4+6.5CO2

[0145] Al₂O₃ + 1.5C + 3Cl₂ = 2AlCl₃ + 1.5CO₂ or Al₂O₃ + 3C + 3Cl₂ = 2AlCl₃ + 3CO₂

[0146] SiO₂ + C + 2Cl₂ = SiCl₄ + CO₂ or SiO₂ + 2C + 2Cl₂ = SiCl₄ + 2CO

[0147] TiO₂ + C + 2Cl₂ = TiCl₄ + CO₂ or TiO₂ + 2C + 2Cl₂ = TiCl₄ + 2CO₂

[0148] MgO + 0.5C + Cl₂ = MgCl₂ + 0.5CO₂ or MgO + C + Cl₂ = MgCl₂ + CO₂

[0149] CaO + 0.5C + Cl₂ = CaCl₂ + CO₂ or CaO + C + Cl₂ = CaCl₂ + CO

[0150] Fe₂O₃ + 1.5C + 3Cl₂ = 2FeCl₃ + 1.5CO₂ or Fe₂O₃ + 3C + 3Cl₂ = 2FeCl₃ + 3CO₂

[0151] Li₂O + 0.5C + Cl₂ = 2LiCl + 0.5CO₂ or Li₂O + C + Cl₂ = 2LiCl + CO₂

[0152] K₂O + 0.5C + Cl₂ = 2KCl + 0.5CO₂ or K₂O + C + Cl₂ = 2KCl + CO₂

[0153] Ga₂O₃ + 3C + 3Cl₂ = 2GaCl₃ + 3CO or Ga₂O₃ + 3C + 3Cl₂ = 2GaCl₃ + 3CO

[0154] GeO₂ + C + 2Cl₂ = GeCl₄ + CO₂ or GeO₂ + 2C + 2Cl₂ = GeCl₄ + 2CO₂

[0155] (2) The uniformly mixed raw materials are added to the stirred fluidized bed through the side stirring shaft. The chlorination process is carried out at a reaction temperature of 1100℃ and a reaction time of 60min, with an oxygen to chlorine ratio of 0.2:1.

[0156] (3) Stirred fluidized bed, with the side stirring paddle shaft and the furnace body at an angle of 35°, stirring speed of 150 rpm, and top stirring paddle speed of 80 rpm. Compared with traditional fluidized bed, the large bubble rate is reduced by 70%, the heat transfer efficiency is increased by 42%, and the dust carrying rate is reduced by 1.0%.

[0157] (4) The gas phase chlorination product is processed by a three-stage spiral propulsion condenser. The spiral propulsion agitator is driven at a speed of 60 rpm, which pushes the condensed product out through the discharge airlock. The first stage is controlled at 280℃ to obtain crude ferric chloride, the second stage is controlled at 180℃ to obtain crude aluminum chloride, and the third stage is controlled at 30℃ to obtain crude silicon tetrachloride. Through the spiral propulsion condenser, the separation efficiency of flue gas and chloride is 99%, and the water content of the obtained chloride is 0.1%.

[0158] (5) Aluminum chloride is further refined and purified by removing iron with aluminum powder to obtain high-purity aluminum chloride with a mass fraction of 99.9%. Silicon tetrachloride is obtained by distillation to obtain high-purity silicon tetrachloride with a mass fraction of 99.9%. The enriched rare and dispersed metal chlorides can be further separated and purified. The gas phase product purification and oxidation process reaction is as follows:

[0159] Al + 0.75TiCl₄ = AlCl₃ + 0.75Ti

[0160] Al + GaCl3 = AlCl3 + Ga

[0161] Al + FeCl3 = AlCl3 + Fe

[0162] (6) The discharged carbon dioxide and chlorine are compressed and separated. The chlorine is returned to the chlorination section as a chlorine source, and the carbon dioxide reacts with biomass carbon to produce carbon monoxide, which is returned to the chlorination section as a carbon source. Specifically, carbon dioxide reacts with carbon-containing raw materials in a closed rotary roasting furnace to produce carbon monoxide. The roasting temperature is 900℃, the roasting time is 50 min, the residual carbon content in the carbon-containing raw materials after roasting is 0.03 wt%, and the mass fraction of carbon monoxide in the resulting flue gas is 90%.

[0163] After treatment by this method, the chlorination efficiency of alumina is 96%; after separation and purification of the gas phase product, anhydrous aluminum chloride with a mass fraction of 99.9% is obtained; silicon tetrachloride is distilled to obtain high-purity silicon tetrachloride with a mass fraction of 99.9%, and the enriched rare and dispersed metal chlorides can be further separated and purified.

[0164] Example 6

[0165] A method for preparing high-purity anhydrous aluminum chloride mainly includes the following steps:

[0166] (2) Using coal gasification slag as raw material, carbon monoxide as carbon source, and biomass carbon as supplementary carbon source, ensuring that the carbon-to-coal gasification slag mass ratio of carbon monoxide and biomass carbon is 1:1, the particle size ratio of coal gasification slag to supplementary biomass carbon is 0.5:1, and the chlorination reaction of coal gasification slag is as follows:

[0167] Al₂O₃ + 1.5C + 3Cl₂ = 2AlCl₃ + 1.5CO₂ or Al₂O₃ + 3C + 3Cl₂ = 2AlCl₃ + 3CO₂

[0168] SiO₂ + C + 2Cl₂ = SiCl₄ + CO₂ or SiO₂ + 2C + 2Cl₂ = SiCl₄ + 2CO

[0169] TiO₂ + C + 2Cl₂ = TiCl₄ + CO₂ or TiO₂ + 2C + 2Cl₂ = TiCl₄ + 2CO₂

[0170] MgO + 0.5C + Cl₂ = MgCl₂ + 0.5CO₂ or MgO + C + Cl₂ = MgCl₂ + CO₂

[0171] CaO + 0.5C + Cl₂ = CaCl₂ + CO₂ or CaO + C + Cl₂ = CaCl₂ + CO

[0172] Fe₂O₃ + 1.5C + 3Cl₂ = 2FeCl₃ + 1.5CO₂ or Fe₂O₃ + 3C + 3Cl₂ = 2FeCl₃ + 3CO₂

[0173] Li₂O + 0.5C + Cl₂ = 2LiCl + 0.5CO₂ or Li₂O + C + Cl₂ = 2LiCl + CO₂

[0174] K₂O + 0.5C + Cl₂ = 2KCl + 0.5CO₂ or K₂O + C + Cl₂ = 2KCl + CO₂

[0175] Ga₂O₃ + 3C + 3Cl₂ = 2GaCl₃ + 3CO or Ga₂O₃ + 3C + 3Cl₂ = 2GaCl₃ + 3CO

[0176] GeO₂ + C + 2Cl₂ = GeCl₄ + CO₂ or GeO₂ + 2C + 2Cl₂ = GeCl₄ + 2CO₂

[0177] (2) The uniformly mixed raw materials are added to the stirred fluidized bed through the side stirring shaft. The chlorination process is carried out at a reaction temperature of 700℃ and a reaction time of 30min, with an oxygen to chlorine ratio of 0.2:1.

[0178] (3) Stirred fluidized bed, with the side stirring paddle shaft and the furnace body having an angle of 70°, stirring speed of 120 rpm, and top stirring paddle speed of 70 rpm. Compared with traditional fluidized bed, the large bubble rate is reduced by 65%, the heat transfer efficiency is increased by 40%, and the dust carrying rate is reduced by 1.0%.

[0179] (4) The gas phase chlorination product is processed by a three-stage spiral propulsion condenser. The spiral propulsion agitator is driven at a speed of 40 rpm, which pushes the condensed product out through the discharge airlock. The first stage is controlled at 300℃ to obtain crude ferric chloride, the second stage is controlled at 180℃ to obtain crude aluminum chloride, and the third stage is controlled at 5℃ to obtain crude silicon tetrachloride. Through the spiral propulsion condenser, the separation efficiency of flue gas and chloride is 99%, and the water content of the obtained chloride is 0.1%.

[0180] (5) Aluminum chloride is de-ironized by aluminum powder to obtain high-purity aluminum chloride with a mass fraction of 99.9%, and silicon tetrachloride is distilled to obtain high-purity silicon tetrachloride with a mass fraction of 99.9%. The enriched rare and dispersed metal chlorides can be further separated and purified.

[0181] The gas-phase product purification and oxidation process is as follows:

[0182] Al + 0.75TiCl₄ = AlCl₃ + 0.75Ti

[0183] Al + GaCl3 = AlCl3 + Ga

[0184] Al + FeCl3 = AlCl3 + Fe

[0185] (6) The discharged carbon dioxide and chlorine are compressed and separated. The chlorine is returned to the chlorination section as a chlorine source, and the carbon dioxide reacts with biomass carbon to produce carbon monoxide, which is returned to the chlorination section as a carbon source. Specifically, carbon dioxide reacts with carbon-containing raw materials in a closed rotary roasting furnace to produce carbon monoxide. The roasting temperature is 700℃, the roasting time is 60 min, the residual carbon content in the carbon-containing raw materials after roasting is 0.03 wt%, and the mass fraction of carbon monoxide in the resulting flue gas is 85%.

[0186] After treatment by this method, the chlorination efficiency of alumina is 96%; after separation and purification of the gas phase product, anhydrous aluminum chloride with a mass fraction of 99.9% is obtained; silicon tetrachloride is distilled to obtain high-purity silicon tetrachloride with a mass fraction of 99.9%, and the enriched rare and dispersed metal chlorides can be further separated and purified.

[0187] Example 7

[0188] A method for preparing high-purity anhydrous aluminum chloride mainly includes the following steps:

[0189] (1) Using coal gangue as raw material, carbon monoxide as carbon source, and biomass carbon as supplementary carbon source, ensuring that the mass ratio of carbon to coal gangue in carbon monoxide and biomass carbon is 1.5:1, and the particle size ratio of coal gangue to supplementary biomass carbon is 0.8:1, the chlorination reaction of coal gasification slag is as follows:

[0190] Al₂O₃ + 1.5C + 3Cl₂ = 2AlCl₃ + 1.5CO₂ or Al₂O₃ + 3C + 3Cl₂ = 2AlCl₃ + 3CO₂

[0191] SiO₂ + C + 2Cl₂ = SiCl₄ + CO₂ or SiO₂ + 2C + 2Cl₂ = SiCl₄ + 2CO

[0192] TiO₂ + C + 2Cl₂ = TiCl₄ + CO₂ or TiO₂ + 2C + 2Cl₂ = TiCl₄ + 2CO₂

[0193] MgO + 0.5C + Cl₂ = MgCl₂ + 0.5CO₂ or MgO + C + Cl₂ = MgCl₂ + CO₂

[0194] CaO + 0.5C + Cl₂ = CaCl₂ + CO₂ or CaO + C + Cl₂ = CaCl₂ + CO

[0195] Fe₂O₃ + 1.5C + 3Cl₂ = 2FeCl₃ + 1.5CO₂ or Fe₂O₃ + 3C + 3Cl₂ = 2FeCl₃ + 3CO₂

[0196] Li₂O + 0.5C + Cl₂ = 2LiCl + 0.5CO₂ or Li₂O + C + Cl₂ = 2LiCl + CO₂

[0197] K₂O + 0.5C + Cl₂ = 2KCl + 0.5CO₂ or K₂O + C + Cl₂ = 2KCl + CO₂

[0198] Ga₂O₃ + 3C + 3Cl₂ = 2GaCl₃ + 3CO or Ga₂O₃ + 3C + 3Cl₂ = 2GaCl₃ + 3CO

[0199] GeO₂ + C + 2Cl₂ = GeCl₄ + CO₂ or GeO₂ + 2C + 2Cl₂ = GeCl₄ + 2CO₂

[0200] (2) The uniformly mixed raw materials are added to the stirred fluidized bed through the side stirring shaft. The chlorination process is carried out at a reaction temperature of 900℃ and a reaction time of 60min, with an oxygen to chlorine ratio of 0.3:1.

[0201] (3) Stirred fluidized bed, with the side stirring paddle shaft and the furnace body having an angle of 75°, stirring speed of 150 rpm, and top stirring paddle speed of 100 rpm. Compared with traditional fluidized bed, the large bubble rate is reduced by 70%, the heat transfer efficiency is increased by 45%, and the dust carrying rate is reduced by 1.0%.

[0202] (4) The gas phase chlorination product is processed by a three-stage spiral propulsion condenser. The spiral propulsion agitator is driven at a speed of 10 rpm, which pushes the condensed product out through the discharge airlock. The first stage is controlled at 300℃ to obtain crude ferric chloride, the second stage is controlled at 180℃ to obtain crude aluminum chloride, and the third stage is controlled at 20℃ to obtain crude silicon tetrachloride. Through the spiral propulsion condenser, the separation efficiency of flue gas and chloride is 99%, and the water content of the obtained chloride is 0.1%.

[0203] (5) Aluminum chloride is de-ironized by aluminum powder to obtain high-purity aluminum chloride with a mass fraction of 99.9%, and silicon tetrachloride is distilled to obtain high-purity silicon tetrachloride with a mass fraction of 99.9%. The enriched rare and dispersed metal chlorides can be further separated and purified.

[0204] The gas-phase product purification and oxidation process is as follows:

[0205] Al + 0.75TiCl₄ = AlCl₃ + 0.75Ti

[0206] Al + GaCl3 = AlCl3 + Ga

[0207] Al + FeCl3 = AlCl3 + Fe

[0208] (6) The discharged carbon dioxide and chlorine are compressed and separated. The chlorine is returned to the chlorination section as a chlorine source, and the carbon dioxide reacts with biomass carbon to produce carbon monoxide, which is returned to the chlorination section as a carbon source. Specifically, carbon dioxide reacts with carbon-containing raw materials in a closed rotary roasting furnace to produce carbon monoxide. The roasting temperature is 800℃, the roasting time is 60 min, the residual carbon content in the carbon-containing raw materials after roasting is 0.05 wt%, and the mass fraction of carbon monoxide in the resulting flue gas is 80%.

[0209] After treatment by this method, the chlorination efficiency of alumina is 97%; after separation and purification of the gas phase product, anhydrous aluminum chloride with a mass fraction of 99.9% is obtained; silicon tetrachloride is distilled to obtain high-purity silicon tetrachloride with a mass fraction of 99.9%, and the enriched rare and dispersed metal chlorides can be further separated and purified.

[0210] Example 8

[0211] A method for preparing high-purity anhydrous aluminum chloride mainly includes the following steps:

[0212] (1) Using alumina as raw material, carbon monoxide as carbon source, and biomass carbon as supplementary carbon source, ensuring that the mass ratio of carbon to alumina in carbon monoxide and biomass carbon is 1.5:1, the particle size ratio of alumina to supplementary biomass carbon is 0.8:1, and the chlorination reaction of alumina with carbon monoxide and chlorine is as follows:

[0213] Al₂O₃ + 3CO + 3Cl₂ = 2AlCl₃ + 3CO₂

[0214] (2) The uniformly mixed raw materials are added to the stirred fluidized bed through the side stirring shaft. The chlorination process is carried out at a reaction temperature of 900℃ and a reaction time of 60min. The mass ratio of carbon monoxide to alumina is 0.4:1 and the ratio of oxygen to chlorine is 0.3:1. Alumina reacts with chlorine to produce anhydrous aluminum chloride.

[0215] (3) Stirred fluidized bed, with the side stirring paddle shaft and the furnace body having an angle of 75°, stirring speed of 150 rpm, and top stirring paddle speed of 80 rpm. Compared with traditional fluidized bed, the large bubble rate is reduced by 70%, the heat transfer efficiency is increased by 45%, and the dust carrying rate is reduced by 1.0%.

[0216] (4) The gas phase chlorination product is condensed by a multi-stage spiral propulsion condenser. The spiral propulsion agitator is 5 rpm, which pushes the condensed product out of the discharge airlock and encapsulates it. The separation efficiency of flue gas and chloride is 99%, and the water content of the obtained chloride is 0.1%.

[0217] (5) The discharged carbon dioxide and chlorine are compressed and separated. The chlorine is returned to the chlorination section as a chlorine source, and the carbon dioxide reacts with biomass carbon to produce carbon monoxide, which is returned to the chlorination section as a carbon source. Specifically, carbon dioxide reacts with carbon-containing raw materials in a closed rotary roasting furnace to produce carbon monoxide. The roasting temperature is 1000℃, the roasting time is 20 min, the residual carbon content in the carbon-containing raw materials after roasting is 0.05 wt%, and the mass fraction of carbon monoxide in the resulting flue gas is 80%.

[0218] After treatment by this method, the chlorination efficiency of alumina is 97%; after separation and purification of the gas phase product, anhydrous aluminum chloride with a mass fraction of 99.9% is obtained; silicon tetrachloride is distilled to obtain high-purity silicon tetrachloride with a mass fraction of 99.9%, and the enriched rare and dispersed metal chlorides can be further separated and purified.

Claims

1. A method for preparing high-purity anhydrous aluminum chloride, characterized in that, The main steps include: Step 1: Thoroughly grind, mix, and preheat the reducing agent, aluminum-containing raw materials, and supplementary biomass carbon; Step 2: After preheating and mixing, the mixture is conveyed to a stirred fluidized bed, where supplementary chlorine and oxygen are introduced to carry out a chlorination reaction, generating high-temperature flue gas. The stirred fluidized bed is one of the fluidized bed or suspended fluidized bed, and consists of a discharge airlock, an air inlet, a fluidized bed furnace body, a side stirring feed inlet, a side stirring paddle, a top stirring paddle, a flue gas passage, a flue gas outlet, and a stirring motor. Step 3: Gaseous aluminum chloride in the high-temperature flue gas is continuously discharged in powder form through a screw propeller condenser, yielding crude anhydrous aluminum chloride, crude silicon tetrachloride, and chlorine-containing flue gas; Step 4: Crude anhydrous aluminum chloride is further refined and purified by reducing distillation to obtain high-purity aluminum chloride; crude silicon tetrachloride is obtained by distillation to obtain high-purity silicon tetrachloride, and the enriched rare and dispersed metal chlorides can be further separated and purified. In step 2, in the stirred fluidized bed, the discharge airlock, air inlet, and flue gas outlet are connected to the fluidized bed furnace body via flanges. The function of the discharge airlock is to ensure unidirectional discharge of solid residue. A top stirring paddle is installed on the top of the furnace body, which rotates under the drive of a stirring motor at a speed of 40~150 rpm. The top stirring uses centrifugal force to separate fine particles back into the bed. The side stirring paddle has a hollow internal structure for conveying solid raw materials into the fluidized bed. The angle between the stirring paddle shaft and the furnace body is continuously adjustable from 0° to 90°, and the stirring speed is 20~150 rpm. In the chlorination reaction process in step 2, oxygen and chlorine are introduced into the reaction, wherein the ratio of oxygen to chlorine is (0.01~0.3):

1. In step 3, the spiral propulsion condenser consists of multiple parts, including a stirring motor, a spiral propulsion agitator, a flue gas inlet, a discharge airlock, a flue gas outlet, and a tank. The spiral propulsion agitator, flue gas outlet, discharge airlock, and flue gas outlet are connected to the tank flange. The shaft of the spiral propulsion agitator is hollow. The remaining flue gas after condensation is discharged through the axial flue gas outlet. The spiral propulsion agitator rotates under the action of the stirring motor. The propulsion speed of the spiral propulsion agitator is 1~50 rpm, which pushes the condensed product to move towards the bottom discharge airlock. Under the action of the discharge airlock, the condensed product is discharged in one direction. The crude anhydrous aluminum chloride has a condensation recovery efficiency greater than 99% and a water absorption rate of less than 0.1%. In step 1, the reducing agent is carbon monoxide; the mass ratio of carbon in carbon monoxide to aluminum-containing raw material in biomass carbon is (0.1~3):1, and the particle size ratio of aluminum-containing raw material to supplementary biomass carbon is 1:(1~8); wherein, carbon monoxide is used as the carbon source, and biomass carbon is used as the supplementary carbon source.

2. The method for preparing high-purity anhydrous aluminum chloride according to claim 1, characterized in that, The stirred fluidized bed reduces the occurrence rate of large bubbles in the bed to below 60%, increases the system's heat transfer efficiency to above 30%, and reduces the dust carryover rate to below 2%.

3. The method for preparing high-purity anhydrous aluminum chloride according to claim 1, characterized in that, In step 1, the aluminum-containing raw material is one of the following: alumina, gibbsite, boehmite, kaolin, illite, pyrophyllite, red mud, fly ash, coal gangue, or coal gasification slag.

4. The method for preparing high-purity anhydrous aluminum chloride according to claim 1, characterized in that, In step 2, the chlorination reaction temperature is 300~1100℃; the reaction time is 1~120min. During the chlorination reaction, the oxygen introduced is oxygen-enriched air with an oxygen content of 25% to 100%. The chlorination efficiency of alumina in the chlorination reaction is greater than 93%; The high-temperature flue gas is used for heat exchange with solid raw materials, which improves the heat utilization rate by 60%.

5. The method for preparing high-purity anhydrous aluminum chloride according to claim 1, characterized in that, In step 3, the chlorine-containing flue gas is compressed and separated to generate chlorine, carbon dioxide, biomass carbon, and solid residue. The chlorine is returned to the chlorination reaction stage as a chlorinating agent; the carbon dioxide reacts with the biomass carbon in a gas-solid reaction to produce carbon monoxide, which is returned to the chlorination stage as a carbon source; and the remaining solid residue is used as raw material for kaolin or silicon fertilizer.

6. A method for preparing high-purity anhydrous aluminum chloride according to claim 5, characterized in that, The carbon dioxide and biomass carbon undergo a gas-solid reaction in a closed rotary roaster to produce carbon monoxide. The roasting temperature is 700~1100℃ and the roasting time is 10~120min. After roasting, the carbon residue in the carbon-containing raw material is less than 0.06 wt%, and the mass fraction of carbon monoxide in the obtained flue gas is greater than 75%.

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