Method for recovering valuable elements in liquid obtained after wet desulphurization of bauxite

Abstract

The invention discloses a method for recovering valuable elements in liquid obtained after bauxite wet desulphurization, and relates to the technical field of bauxite resource utilization. Comprising the following steps: carrying out ceramic membrane filtration pretreatment on the bauxite wet desulfurization liquid to remove impurities; the silicon element is recycled in a targeted manner through a compound flocculation-calcination process to obtain the white carbon black; the iron element is recycled through ozone oxidation-ammonium bicarbonate precipitation, and high-purity iron oxide is prepared; separating and purifying an aluminum element through a seed crystal induction-calcination process to obtain metallurgical-grade aluminum oxide; a fluorine-containing precipitant is used for selectively precipitating and recovering magnesium element to obtain a high-quality magnesium salt product; and neutralizing the tail liquid, and discharging after reaching the standard. According to the method, accurate separation and high-valued utilization of four elements of aluminum, iron, silicon and magnesium are realized through a synergistic process of targeted recovery of silicon, gradient separation of iron and aluminum and selective precipitation of magnesium, and the problems of silicon resource waste, low element separation efficiency, insufficient product purity, secondary pollution and the like in a traditional process are thoroughly solved; all-component resource comprehensive utilization of desulfurized liquid resources is achieved.

Description

A method for recovering valuable elements from bauxite wet desulfurization liquid Technical Field

[0001] This invention relates to the field of bauxite resource utilization technology, specifically to a method for recovering valuable elements from the liquid after wet desulfurization of bauxite. Background Technology

[0002] After wet desulfurization treatment of high-sulfur bauxite, the resulting desulfurization liquid contains not only conventional valuable elements such as aluminum, iron, and magnesium, but also a large amount of silicon (in the form of silicate ions and silica gel particles). However, existing wet desulfurization liquid treatment technologies generally have significant drawbacks: First, silicon is mostly discarded as waste residue, failing to achieve high-value utilization, resulting in resource waste and increased solid waste disposal costs; second, the separation of aluminum, iron, and magnesium relies on a single precipitation or extraction process, resulting in low separation efficiency (aluminum-iron separation efficiency <85%, magnesium recovery rate <88%) and insufficient product purity; third, some processes use excessive addition of strong acids and alkalis, leading to severe equipment corrosion and posing a risk of secondary pollution.

[0003] Currently, among mainstream treatment technologies, neutralization precipitation can only recover a portion of aluminum and iron, while silicon and magnesium are lost with the waste residue, resulting in a resource utilization rate of less than 60%. Solvent extraction can improve the separation of aluminum and iron, but the extractant is costly, volatile, and cannot recover silicon. Evaporation crystallization only recovers mixed salts, resulting in low added value, and the presence of silicon affects the purity of the salts. Currently, no process can simultaneously achieve precise separation and high-value recovery of aluminum, iron, silicon, and magnesium, especially lacking targeted recovery technology for silicon. This leads to the underutilization of the resource potential of bauxite wet desulfurization liquid, contradicting the requirements of green and circular development. Summary of the Invention

[0004] This invention aims to solve the problems of unrecovered silicon, low precision in aluminum-iron-magnesium separation, insufficient product purity, and secondary pollution in the treatment of post-desulfurization liquid from bauxite wet desulfurization. It provides a method for recovering valuable elements from the post-desulfurization liquid of bauxite. This method achieves targeted recovery of silicon and gradient separation of aluminum, iron, and magnesium, respectively obtaining high-purity silica, metallurgical-grade alumina, high-purity iron oxide, and high-quality magnesium salts. This achieves a comprehensive resource utilization rate of ≥95% for the post-desulfurization liquid, with no secondary pollution, providing technical support for industrial application.

[0005] Therefore, this invention provides a method for recovering valuable elements from bauxite wet desulfurization liquid, comprising the following steps: S1, pretreatment and impurity removal: the bauxite wet desulfurization liquid is filtered through a ceramic membrane to remove impurities, obtaining a clarified filtrate; the pH of the clarified filtrate is adjusted to acidic, and after stirring evenly, a homogenized pretreatment liquid is obtained; S2, targeted recovery of silicon: a cationic flocculant is added to the homogenized pretreatment liquid to react and form silica gel precipitate; after solid-liquid separation, a silica gel filter cake and a desiliconized filtrate are obtained; the silica gel filter cake is washed, dried, and calcined to obtain a silica product; S3, oxidation precipitation and iron removal: ozone is introduced into the desiliconized filtrate for oxidation to remove Fe. 2+ Oxidized to Fe 3+ Subsequently, ammonium bicarbonate is added to adjust the pH to generate FeOOH precipitate; after solid-liquid separation, iron slag and iron-removed filtrate are obtained; the iron slag is washed and calcined to obtain iron oxide product; S4, aluminum separation and purification: ammonia water is added to the iron-removed filtrate to adjust the pH, and seed crystals are added for aging and crystallization to obtain Al(OH)3 precipitate; after solid-liquid separation, Al(OH)3 filter cake and aluminum precipitation filtrate are obtained; the Al(OH)3 filter cake is washed and calcined to obtain metallurgical grade alumina product; S5, selective recovery of magnesium: a fluorine-containing precipitant is added to the aluminum precipitation filtrate to react and generate MgF2 precipitate; after solid-liquid separation, MgF2 filter cake and tailings are obtained; the MgF2 filter cake is washed and dried to obtain MgF2 product; S6, tailings treatment: the tailings are neutralized and discharged after meeting the standards.

[0006] Further, in step S1, the pore size of the ceramic membrane is 50nm-100nm, and the pH is adjusted to 2.5-3.0.

[0007] Further, in step S2, the cationic flocculant is a mixture of polyaluminum chloride and polyacrylamide in a mass ratio of 3:1. The amount of cationic flocculant added is 0.05%-0.1% of the mass of the homogenized pretreatment liquid. The reaction temperature is 40℃-50℃, the reaction time is 30min-60min, the calcination temperature is 550℃-600℃, and the calcination time is 3h-5h.

[0008] Furthermore, in step S2, the purity of SiO2 in the obtained silica is ≥98%, and the recovery rate of silicon is not less than 94%.

[0009] Further, in step S3, the ozone concentration is 75 mg / L-100 mg / L, the gas-liquid mass ratio is (3-5):1, the oxidation reaction temperature is 50℃-60℃, and the oxidation endpoint ORP ≥ 450 mV; the addition of ammonium bicarbonate to adjust the pH and generate FeOOH precipitate includes: adjusting the pH to 4.5-5.0 with 15%-20% ammonium bicarbonate, and maintaining the reaction at 50℃-60℃ for 1.5-2 hours to allow FeOOH to precipitate. 3+ Hydrolysis produces FeOOH precipitate.

[0010] Furthermore, the iron oxide product is Fe2O3 with a purity of not less than 97% and an iron recovery rate of not less than 96%.

[0011] Further, in step S4, the ammonia water has a mass fraction of 20%-30%, and the pH is adjusted to 6.0-6.5; the seed crystal is boehmite, and its addition amount is 5%-8% of the theoretical Al(OH)3 mass; the aging temperature is 50℃-60℃, and the aging time is 2.5h-3h; the calcination temperature is 1200℃-1250℃, and the calcination time is 2h-3h.

[0012] Furthermore, the purity of Al2O3 in the metallurgical grade alumina product is not less than 98.5%, and the aluminum recovery rate is not less than 95%.

[0013] Further, in step S5, the fluorine-containing precipitant is a sodium fluoride solution, and its addition amount is 1.2-1.3 times the molar amount of magnesium ions in the filtrate after aluminum precipitation; the reaction temperature is 40℃-50℃, and the reaction time is 1.5h-2h.

[0014] Furthermore, the MgF2 product has a purity of not less than 96% and a magnesium recovery rate of not less than 93%.

[0015] Compared with existing technologies, this invention has at least the following beneficial effects: This invention achieves efficient separation and high-value recovery of four valuable elements—silicon, aluminum, iron, and magnesium—from the wet desulfurization liquid of bauxite through a synergistic process of "targeted silicon recovery, gradient separation of iron and aluminum, and selective precipitation of magnesium." Its core beneficial effects can be summarized in the following three points: 1) High resource utilization: For the first time, targeted recovery of silicon (in the form of high-purity silica) from the desulfurization liquid is achieved, while simultaneously and efficiently extracting aluminum, iron, and magnesium. The overall resource utilization rate is ≥95%, solving the industry problem of silicon resource waste.

[0016] 2) High product value: The four products obtained (white carbon black, metallurgical grade alumina, high-purity iron oxide, and high-quality magnesium fluoride) have high purity and high added value, which are far superior to traditional mixed salts or low-purity products.

[0017] 3) Green and economical process: It adopts clean technologies such as ozone oxidation, avoids the use of strong acids and alkalis, and reduces secondary pollution and equipment corrosion from the source; the process flow is continuous and the reagent cost is low, which has significant environmental advantages and industrialization potential. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in the embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0019] Figure 1 is a process flow diagram of valuable element recovery from bauxite wet desulfurization liquid provided in an embodiment of the present invention. Detailed Implementation

[0020] To better understand the above technical solutions, the technical solutions of the embodiments of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0021] This invention provides a method for recovering valuable elements from bauxite wet desulfurization liquid, comprising the following steps: S1, pretreatment and impurity removal: the bauxite wet desulfurization liquid is filtered through a ceramic membrane to remove impurities, obtaining a clarified filtrate; the pH of the clarified filtrate is adjusted to acidic, and after stirring evenly, a homogenized pretreatment liquid is obtained; S2, targeted recovery of silicon: a cationic flocculant is added to the homogenized pretreatment liquid to react and form silica gel precipitate; after solid-liquid separation, a silica gel filter cake and a desiliconized filtrate are obtained; the silica gel filter cake is washed, dried, and calcined to obtain a silica product; S3, oxidation precipitation and iron removal: ozone is introduced into the desiliconized filtrate for oxidation to remove Fe. 2+ Oxidized to Fe 3+Subsequently, ammonium bicarbonate is added to adjust the pH to generate FeOOH precipitate; after solid-liquid separation, iron slag and iron-removed filtrate are obtained; the iron slag is washed and calcined to obtain iron oxide product; S4, aluminum separation and purification: ammonia water is added to the iron-removed filtrate to adjust the pH, and seed crystals are added for aging and crystallization to obtain Al(OH)3 precipitate; after solid-liquid separation, Al(OH)3 filter cake and aluminum precipitation filtrate are obtained; the Al(OH)3 filter cake is washed and calcined to obtain metallurgical grade alumina product; S5, selective recovery of magnesium: a fluorine-containing precipitant is added to the aluminum precipitation filtrate to react and generate MgF2 precipitate; after solid-liquid separation, MgF2 filter cake and tailings are obtained; the MgF2 filter cake is washed and dried to obtain MgF2 product; S6, tailings treatment: the tailings are neutralized and discharged after meeting the standards.

[0022] Understandably, existing wet desulfurization liquid treatment technologies for bauxite face multiple technical bottlenecks: 1) Serious waste of silicon resources: Silicon in the desulfurization liquid mainly exists in the form of silica gel and silicate ions. Existing processes do not specifically recover it and directly discharge it with the waste residue, which wastes valuable silicon resources and increases the pressure of solid waste treatment; 2) Poor separation effect of aluminum and iron: Traditional neutralization precipitation method easily forms mixed aluminum and iron hydroxide precipitates, which are difficult to separate in the future. The purity of aluminum products is <95% and the iron recovery rate is <90%. Although solvent extraction method can improve the separation effect, it has the problems of reagent pollution and high cost; 3) Insufficient purity of magnesium recovery: Magnesium often co-precipitates with calcium and impurity ions. Existing processes lack selective recovery technology, and the purity of magnesium products is <90%, resulting in low added value; 4) Risk of secondary pollution: Some processes use excessive amounts of acid, alkali or toxic reagents, resulting in excessive waste liquid discharge, fast equipment corrosion rate (annual corrosion rate >0.8mm), and high operating costs.

[0023] In summary, existing technologies cannot simultaneously achieve efficient recycling and high-value conversion of silicon, aluminum, iron, and magnesium, resulting in low comprehensive resource utilization rates and failing to meet the environmental and economic benefits requirements of industrial production.

[0024] This invention addresses the core problems of insufficient silicon recovery, low precision in aluminum-iron-magnesium separation, and inadequate resource utilization in existing technologies. It employs an innovative process of "targeted silicon recovery - gradient separation of aluminum and iron - selective precipitation of magnesium," which, compared to existing technologies, offers the following significant advantages: 1) Comprehensive resource utilization: For the first time, it achieves simultaneous recovery of silicon, aluminum, iron, and magnesium from the desulfurization liquid, with silicon recovery rate ≥94% (white carbon black purity ≥98%), aluminum recovery rate ≥95% (Al2O3 purity ≥98.5%), iron recovery rate ≥96% (Fe2O3 purity ≥97%), and magnesium recovery rate ≥93% (MgF2 purity ≥96%), resulting in a resource utilization rate ≥95%; 2) High-value products: The recovered products include white carbon black (industrial grade)... The process uses industrial-grade fillers, metallurgical-grade Al2O3, high-purity Fe2O3 (pigment / magnetic material raw materials), and MgF2 (fluoride salt raw materials), increasing added value by more than 60% compared to traditional mixed products; 3) Environmentally friendly: low-pollution reagents such as ozone, ammonium bicarbonate, and ammonia are used, with no toxic or harmful substances emitted. The tail liquid meets emission standards after neutralization, and the amount of solid waste generated is reduced by 40% compared to traditional processes; 4) Cost-efficient: the combination of ceramic membrane filtration and compound flocculant reduces pretreatment costs. Ozone oxidation has high efficiency and low reagent consumption. The overall operating cost is reduced by 30%-35% compared to solvent extraction, and the equipment corrosion rate is ≤0.3mm / year; 5) Simple and easy-to-promote process: the steps are continuous, no complex equipment is required, and all parameters are easy to control, making it suitable for large-scale industrial production.

[0025] In some embodiments, in step S1, the pore size of the ceramic membrane is 50nm-100nm, and the pH is adjusted to 2.5-3.0.

[0026] Specifically, the pretreatment uses ceramic membrane filtration, which improves the impurity removal rate by 15% compared to plate and frame filtration, laying the foundation for subsequent element separation.

[0027] In some embodiments, in step S2, the cationic flocculant is a mixture of polyaluminum chloride and polyacrylamide in a mass ratio of 3:1. The amount of cationic flocculant added is 0.05%-0.1% of the mass of the homogenized pretreatment liquid. The reaction temperature is 40℃-50℃, the reaction time is 30min-60min, the calcination temperature is 550℃-600℃, and the calcination time is 3h-5h.

[0028] Specifically, the innovation of the silicon recovery process in this embodiment of the invention lies in the use of a combination of "pH adjustment-compound flocculation-calcination" to specifically recover silicon elements. The optimal parameters are a flocculant compound ratio of 3:1 and pH 2.5-3.0, which ensures that the silica gel precipitation rate is ≥94% and the purity of the white carbon black is ≥98%.

[0029] In some embodiments, in step S3, the ozone concentration is 75 mg / L-100 mg / L, the gas-liquid mass ratio is (3-5):1, the oxidation reaction temperature is 50℃-60℃, and the oxidation endpoint ORP ≥ 450 mV; adjusting the pH to generate FeOOH precipitate includes: adjusting the pH to 4.5-5.0 with ammonium bicarbonate at a mass concentration of 15%-20%, and maintaining the reaction at 50℃-60℃ for 1.5-2 hours to allow FeOOH to precipitate. 3+ Hydrolysis produces FeOOH precipitate.

[0030] Specifically, in the optimization of iron oxidation precipitation, ozone was selected as the oxidant, which produces no secondary pollution. Compared with H2O2 and sodium hypochlorite, the oxidation efficiency was improved by about 20%, and Fe... 3+ The iron was precipitated as FeOOH and then calcined to obtain high-purity Fe2O3 with an iron recovery rate of ≥96%.

[0031] In some embodiments, in step S4, the ammonia water mass fraction is 20%-30%, and the pH is adjusted to 6.0-6.5; the seed crystal is boehmite, and its addition amount is 5%-8% of the theoretical Al(OH)3 mass; the aging temperature is 50℃-60℃, and the aging time is 2.5h-3h; the calcination temperature is 1200℃-1250℃, and the calcination time is 2h-3h.

[0032] Specifically, the aluminum purification parameters are precise. The addition amount of boehmite seed crystals (5%-8%) and the aging temperature (50℃-60℃) work synergistically to promote the crystallization and purification of Al(OH)3, avoid the co-precipitation of impurities, and achieve the metallurgical grade purity of Al2O3 (not less than 98.5%). The aluminum element recovery rate is not less than 95%.

[0033] In some embodiments, in step S5, the fluorine-containing precipitant is a sodium fluoride solution, and its addition amount is 1.2-1.3 times the molar amount of magnesium ions in the filtrate after aluminum precipitation; the reaction temperature is 40℃-50℃, and the reaction time is 1.5h-2h.

[0034] Specifically, in the selective precipitation of magnesium, sodium fluoride is selected as the precipitant. Compared with sodium carbonate and ammonium oxalate, it has higher selectivity for magnesium ions and avoids interference from impurities such as calcium and sodium. The purity of MgF2 product is ≥96% and the magnesium recovery rate is ≥93%.

[0035] In some embodiments, the washing and drying specifications are as follows: all filter cakes are washed with deionized water ≥3 times, and the drying temperature and time are precisely controlled (silica gel 105℃ / 2h, iron slag naturally dried and then calcined, aluminum filter cake washed at 60℃-70℃ and then calcined) to ensure product purity.

[0036] In some embodiments, during the tailings treatment, the tailings obtained in step S5 are neutralized with lime milk to pH 7.0-7.5, and discharged after passing the test; a small amount of precipitate generated during the neutralization process can be returned to the pretreatment process to recover trace amounts of aluminum and iron.

[0037] Example 1: A method for recovering valuable elements from bauxite wet desulfurization liquid. Referring to Figure 1, a method for recovering valuable elements from bauxite wet desulfurization liquid includes the following steps: S1, Pretreatment and impurity removal: Take 200 mL of bauxite wet desulfurization liquid, filter it through a ceramic membrane (50 nm pore size) to remove unreacted slag and large particulate impurities, obtaining a clear filtrate; transfer the clear filtrate to an adjusting tank, adjust the pH to 2.5, and homogenize and stir at 300 r / min for pretreatment to obtain a homogenized filtrate for later use; S2, Targeted recovery of silicon: Add a cationic flocculant (polyaluminum chloride) to the homogenized filtrate. Polyacrylamide (mass ratio 3:1) was added at 0.05% of the filtrate mass. The mixture was stirred at 40℃ for 35 min to allow silicate ions to combine with the flocculant and form silica gel precipitate. Filtration was used to separate the silica gel filter cake and the desiliconized filtrate. The silica gel filter cake was washed three times with deionized water, dried at 105℃ for 2 h, and calcined at 550℃ for 3 h to obtain silica (SiO2 purity 98.1%, silicon recovery rate 94.0%). S3, Oxidation precipitation to remove iron: Ozone (ozone concentration 80 mg / L, gas-liquid mass ratio 4:1) was introduced into the desiliconized filtrate and oxidized by stirring at 50℃ for 1 h to remove Fe from the filtrate. 2+ Completely oxidized to Fe 3+ (ORP = 460 mV), add 15% ammonium bicarbonate to adjust pH to 4.5, and incubate at 50°C for 1.5 h to allow Fe... 3+Hydrolysis produces FeOOH precipitate, PAM flocculant is added, and after standing for 20 minutes, it is filtered to obtain iron slag and filtrate after iron removal. The iron slag is washed, dried, and calcined at 800℃ for 2 hours to obtain Fe2O3 (purity 97.2%, iron recovery rate 96.0%). Separation and purification of S4 and aluminum: 25% ammonia water is added to the filtrate after iron removal to adjust the pH to 6.0. Boehmite seed crystals are added (the amount added is 5% of the theoretical Al(OH)3 mass), and the mixture is aged at 50℃ for 2.5 hours to promote Al(OH)3 crystal growth. Centrifugation separates the Al(OH)3 filter cake and the liquid after aluminum precipitation. The (OH)3 filter cake was washed three times with deionized water at 65℃ to remove adsorbed impurity ions on the surface. Then, it was transferred to a rotary kiln and calcined at 1200℃ for 2 hours to obtain metallurgical grade Al2O3 (purity 98.6%, aluminum recovery rate 95.2%). S5, Selective recovery of magnesium: 10% sodium fluoride (addition amount is 1.2 times the molar amount of magnesium ions) was added to the aluminum precipitation liquid, and the mixture was stirred at 40℃ for 1.5 hours to generate MgF2 precipitate. The MgF2 filter cake and tailings were separated by pressure filtration. After washing and drying, the MgF2 filter cake was used to obtain a high-quality magnesium salt product (MgF2 purity 96.0%, magnesium recovery rate 93.0%). S6, Tailings treatment: The tailings were neutralized with lime milk to pH=7.0 and discharged in compliance with standards.

[0038] Example 2: A method for recovering valuable elements from bauxite wet desulfurization liquid. Referring to Figure 1, a method for recovering valuable elements from bauxite wet desulfurization liquid includes the following steps: S1, Pretreatment and impurity removal: Take 200 mL of bauxite wet desulfurization liquid, filter it through a ceramic membrane (pore size 80 nm) to remove unreacted slag and large particulate impurities, obtaining a clear filtrate; transfer the clear filtrate to an adjusting tank, adjust the pH to 2.7, and homogenize and stir at 300 r / min for pretreatment to obtain a homogenized filtrate for later use; S2, Targeted recovery of silicon: Add a cationic flocculant (polyaluminum chloride) to the homogenized filtrate. Polyacrylamide (mass ratio 3:1) was added at 0.08% of the filtrate mass. The mixture was stirred at 40℃ for 35 min to allow silicate ions to combine with the flocculant and form silica gel precipitate. Filtration was used to separate the silica gel filter cake and the desiliconized filtrate. The silica gel filter cake was washed three times with deionized water, dried at 105℃ for 2 h, and calcined at 580℃ for 3 h to obtain silica (SiO2 purity 98.6%, silicon recovery rate 95.3%). S3, Oxidation precipitation to remove iron: Ozone (ozone concentration 90 mg / L, gas-liquid mass ratio 4:1) was introduced into the desiliconized filtrate and oxidized by stirring at 50℃ for 1 h to remove Fe from the filtrate. 2+ Completely oxidized to Fe 3+ (ORP monitored = 480mV), add 18% ammonium bicarbonate to adjust pH to 4.8, and maintain the reaction at 50℃ for 1.5h to allow Fe... 3+Hydrolysis produces FeOOH precipitate, which is then added as PAM flocculant. After standing for 20 minutes, the mixture is filtered to obtain iron slag and the filtrate after iron removal. The iron slag is washed, dried, and calcined at 800℃ for 2 hours to obtain Fe2O3 (purity 97.8%, iron recovery rate 97.2%). Separation and purification of S4 and aluminum: 25% ammonia solution is added to the filtrate after iron removal to adjust the pH to 6.2. Boehmite seed crystals are added (the amount added is 6% of the theoretical Al(OH)3 mass). The mixture is aged at 60℃ for 2.5 hours to promote Al(OH)3 crystal growth. The Al(OH)3 filter cake and the liquid after aluminum precipitation are obtained by centrifugation. The Al(OH)3 filter cake is washed three times with deionized water at 65℃. To remove surface-adsorbed impurity ions, the product is transferred to a rotary kiln and calcined at 1220℃ for 2 hours to obtain metallurgical-grade Al2O3 (purity 98.9%, aluminum recovery rate 96.5%). S5. Selective recovery of magnesium: 12% sodium fluoride (addition amount 1.25 times the molar amount of magnesium ions) is added to the aluminum-precipitated liquid, and the mixture is stirred at 50℃ for 1.5 hours to generate MgF2 precipitate. The MgF2 filter cake and tailings are separated by pressure filtration. After washing and drying, the MgF2 filter cake yields a high-quality magnesium salt product (MgF2 purity 96.5%, magnesium recovery rate 94.0%). S6. Tailings treatment: The tailings are neutralized to pH 7.0 with lime milk and discharged in compliance with standards.

[0039] Example 3: A method for recovering valuable elements from bauxite wet desulfurization liquid. Referring to Figure 1, a method for recovering valuable elements from bauxite wet desulfurization liquid includes the following steps: S1, Pretreatment and impurity removal: Take 200 mL of bauxite wet desulfurization liquid, filter it through a ceramic membrane (pore size 100 nm) to remove unreacted slag and large particulate impurities, obtaining a clear filtrate; transfer the clear filtrate to an adjusting tank, adjust the pH to 3.0, and homogenize and stir at 300 r / min for pretreatment to obtain a homogenized filtrate for later use; S2, Targeted recovery of silicon: Add a cationic flocculant (polymer) to the homogenized filtrate. Aluminum chloride and polyacrylamide (mass ratio 3:1) were added at 0.1% of the filtrate mass. The mixture was stirred at 50℃ for 35 min to allow silicate ions to combine with the flocculant and form silica gel precipitate. The silica gel filter cake and the desiliconized filtrate were separated by pressure filtration. The silica gel filter cake was washed three times with deionized water, dried at 105℃ for 2 h, and calcined at 600℃ for 3 h to obtain silica (SiO2 purity 99.0%, silicon recovery rate 96.2%). S3, Oxidation precipitation to remove iron: Ozone (ozone concentration 100 mg / L, gas-liquid mass ratio 4:1) was introduced into the desiliconized filtrate and oxidized by stirring at 60℃ for 1 h to remove Fe from the filtrate. 2+ Completely oxidized to Fe 3+ (ORP = 500 mV), add 20% ammonium bicarbonate to adjust pH to 5.0, and incubate at 60℃ for 1.5 h to allow Fe... 3+Hydrolysis produces FeOOH precipitate, PAM flocculant is added, and after standing for 20 minutes, it is filtered to obtain iron slag and iron-removed filtrate. The iron slag is washed, dried, and calcined at 800℃ for 2 hours to obtain Fe2O3 (purity 98.2%, iron recovery rate 98.0%). Separation and purification of S4 and aluminum: 25% ammonia water is added to the iron-removed filtrate to adjust the pH to 6.5, and pseudoboehmite seed crystals are added (the amount added is 8% of the theoretical Al(OH)3 mass). Aging at 60℃ for 2.5 hours promotes Al(OH)3 crystal growth. Centrifugation separates the Al(OH)3 filter cake and the aluminum-precipitated liquid. The (OH)3 filter cake was washed three times with deionized water at 65℃ to remove surface-adsorbed impurity ions, and then transferred to a rotary kiln for calcination at 1250℃ for 2 hours to obtain metallurgical grade Al2O3 (purity 99.2%, aluminum recovery rate 97.5%). S5, Selective recovery of magnesium: 15% sodium fluoride (addition amount 1.3 times the molar amount of magnesium ions) was added to the aluminum precipitation liquid, and the mixture was stirred at 50℃ for 1.5 hours to generate MgF2 precipitate. The MgF2 filter cake and tailings were separated by pressure filtration. After washing and drying, the MgF2 filter cake yielded a high-quality magnesium salt product (MgF2 purity 97.0%, magnesium recovery rate 95.1%). S6, Tailings treatment: The tailings were neutralized with lime milk to pH=7.0 and discharged in compliance with standards.

[0040] Example 4: A method for recovering valuable elements from bauxite wet desulfurization liquid. Referring to Figure 1, a method for recovering valuable elements from bauxite wet desulfurization liquid includes the following steps: S1, Pretreatment and impurity removal: Take 200 mL of bauxite wet desulfurization liquid, filter it through a ceramic membrane (70 nm pore size) to remove unreacted slag and large particulate impurities, obtaining a clear filtrate; transfer the clear filtrate to an adjusting tank, adjust the pH to 2.6, and homogenize and stir at 300 r / min for pretreatment to obtain a homogenized filtrate for later use; S2, Targeted recovery of silicon: Add a cationic flocculant (polyvinyl chloride) to the homogenized filtrate. Aluminum chloride and polyacrylamide (mass ratio 3:1) were added at 0.06% of the filtrate mass. The mixture was stirred at 40℃ for 35 min to allow silicate ions to combine with the flocculant and form silica gel precipitate. Filtration was used to separate the silica gel filter cake and the desiliconized filtrate. The silica gel filter cake was washed three times with deionized water, dried at 105℃ for 2 h, and calcined at 560℃ for 3 h to obtain silica (SiO2 purity 98.2%, silicon recovery rate 94.3%). S3, Oxidation Precipitation to Remove Iron: Ozone (ozone concentration 78 mg / L, gas-liquid mass ratio 4:1) was introduced into the desiliconized filtrate and oxidized by stirring at 50℃ for 1 h to remove Fe from the filtrate. 2+ Completely oxidized to Fe 3+ (ORP = 455mV), add 16% ammonium bicarbonate to adjust pH to 4.6, and incubate at 50℃ for 1.5 hours to allow Fe... 3+Hydrolysis produces FeOOH precipitate, which is then added as PAM flocculant. After standing for 20 minutes, the mixture is filtered to obtain iron slag and the filtrate after iron removal. The iron slag is washed, dried, and calcined at 800℃ for 2 hours to obtain Fe2O3 (purity 97.3%, iron recovery rate 96.1%). Separation and purification of S4 and aluminum: 25% ammonia solution is added to the filtrate after iron removal to adjust the pH to 6.1. Boehmite seed crystals are added (the amount added is 5.5% of the theoretical Al(OH)3 mass). The mixture is aged at 50℃ for 2.5 hours to promote Al(OH)3 crystal growth. The Al(OH)3 filter cake and the liquid after aluminum precipitation are obtained by centrifugation. The Al(OH)3 filter cake is washed with deionized water at 65℃ for 3 hours. First, remove the impurity ions adsorbed on the surface, then transfer to a rotary kiln and calcine at 1210℃ for 2 hours to obtain metallurgical grade Al2O3 (purity 98.7%, aluminum recovery rate 95.5%); S5, selective recovery of magnesium: add sodium fluoride with a mass concentration of 11% (the amount added is 1.22 times the molar amount of magnesium ions) to the aluminum precipitation liquid, stir and react at 40℃ for 1.5 hours to generate MgF2 precipitate, separate by pressure filtration to obtain MgF2 filter cake and tailings liquid, and after washing and drying, obtain high-quality magnesium salt product (MgF2 purity 96.1%, magnesium recovery rate 93.2%); S6, tailings liquid treatment: neutralize the tailings liquid with lime milk to pH=7.0 and discharge it in compliance with standards.

[0041] Example 5: A method for recovering valuable elements from bauxite wet desulfurization liquid. Referring to Figure 1, a method for recovering valuable elements from bauxite wet desulfurization liquid includes the following steps: S1, Pretreatment and impurity removal: Take 200 mL of bauxite wet desulfurization liquid, filter it through a ceramic membrane (90 nm pore size) to remove unreacted slag and large particulate impurities, obtaining a clear filtrate; transfer the clear filtrate to an adjusting tank, adjust the pH to 2.8, and homogenize and stir at 300 r / min for pretreatment to obtain a homogenized filtrate for later use; S2, Targeted recovery of silicon: Add a cationic flocculant (polyvinyl chloride) to the homogenized filtrate. Aluminum chloride and polyacrylamide (mass ratio 3:1) were added at 0.09% of the filtrate mass. The mixture was stirred at 50℃ for 35 min to allow silicate ions to combine with the flocculant and form silica gel precipitate. Filtration was used to separate the silica gel filter cake and the desiliconized filtrate. The silica gel filter cake was washed three times with deionized water, dried at 105℃ for 2 h, and calcined at 590℃ for 3 h to obtain silica (SiO2 purity 98.8%, silicon recovery rate 95.7%). S3, Oxidation Precipitation to Remove Iron: Ozone (ozone concentration 95 mg / L, gas-liquid mass ratio 4:1) was introduced into the desiliconized filtrate and oxidized by stirring at 60℃ for 1 h to remove Fe from the filtrate. 2+ Completely oxidized to Fe 3+ (ORP monitored = 490mV), add 19% ammonium bicarbonate to adjust pH to 4.9, and maintain the reaction at 60℃ for 1.5h to allow Fe... 3+Hydrolysis produces FeOOH precipitate, PAM flocculant is added, and after standing for 20 minutes, it is filtered to obtain iron slag and iron-removed filtrate. The iron slag is washed, dried, and calcined at 800℃ for 2 hours to obtain Fe2O3 (purity 98.0%, iron recovery rate 97.7%). Separation and purification of S4 and aluminum: 25% ammonia water is added to the iron-removed filtrate to adjust the pH to 6.4, and boehmite seed crystals are added (7% of the theoretical Al(OH)3 mass). Aging at 60℃ for 2.5 hours promotes Al(OH)3 crystal growth. Centrifugation separates the Al(OH)3 filter cake and the aluminum-precipitated liquid. The (OH)3 filter cake was washed three times with deionized water at 65℃ to remove adsorbed impurity ions on the surface. Then, it was transferred to a rotary kiln and calcined at 1240℃ for 2 hours to obtain metallurgical grade Al2O3 (purity 99.1%, aluminum recovery rate 97.3%). S5, Selective recovery of magnesium: 14% sodium fluoride (addition amount is 1.28 times the molar amount of magnesium ions) was added to the aluminum precipitation liquid and stirred at 50℃ for 1.5 hours to generate MgF2 precipitate. The MgF2 filter cake and tailings were separated by pressure filtration. After washing and drying, the MgF2 filter cake was used to obtain high-quality magnesium salt product (MgF2 purity 96.8%, magnesium recovery rate 94.8%). S6, Tailings treatment: The tailings were neutralized with lime milk to pH=7.0 and discharged in compliance with standards.

[0042] Example 6: A method for recovering valuable elements from bauxite wet desulfurization liquid. Referring to Figure 1, a method for recovering valuable elements from bauxite wet desulfurization liquid includes the following steps: S1, Pretreatment and impurity removal: Take 200 mL of bauxite wet desulfurization liquid, filter it through a ceramic membrane (pore size 60 nm) to remove unreacted slag and large particulate impurities, obtaining a clear filtrate; transfer the clear filtrate to an adjusting tank, adjust the pH to 2.5, and homogenize and stir at 300 r / min for pretreatment to obtain a homogenized filtrate for later use; S2, Targeted recovery of silicon: Add a cationic flocculant (polyvinyl chloride) to the homogenized filtrate. Aluminum chloride and polyacrylamide (mass ratio 3:1) were added at 0.07% of the filtrate mass. The mixture was stirred at 40℃ for 35 min to allow silicate ions to combine with the flocculant and form silica gel precipitate. Filtration was used to separate the silica gel filter cake and the desiliconized filtrate. The silica gel filter cake was washed three times with deionized water, dried at 105℃ for 2 h, and calcined at 570℃ for 3 h to obtain silica (SiO2 purity 98.3%, silicon recovery rate 94.5%). S3, Oxidation Precipitation to Remove Iron: Ozone (ozone concentration 85 mg / L, gas-liquid mass ratio 4:1) was introduced into the desiliconized filtrate and oxidized by stirring at 50℃ for 1 h to remove Fe from the filtrate. 2+ Completely oxidized to Fe 3+ (ORP monitored = 468mV), add 17% ammonium bicarbonate to adjust pH to 4.7, and maintain the reaction at 50℃ for 1.5h to allow Fe to... 3+Hydrolysis produces FeOOH precipitate, PAM flocculant is added, and after standing for 20 minutes, it is filtered to obtain iron slag and iron-removed filtrate. The iron slag is washed, dried, and calcined at 800℃ for 2 hours to obtain Fe2O3 (purity 97.5%, iron recovery rate 96.4%). Separation and purification of S4 and aluminum: 25% ammonia water is added to the iron-removed filtrate to adjust the pH to 6.0, and pseudoboehmite seed crystals are added (the amount added is 5% of the theoretical Al(OH)3 mass). Aging at 50℃ for 2.5 hours promotes Al(OH)3 crystal growth. Centrifugation separates the Al(OH)3 filter cake and the aluminum-precipitated liquid. The (OH)3 filter cake was washed three times with deionized water at 65℃ to remove adsorbed impurity ions on the surface. Then, it was transferred to a rotary kiln and calcined at 1200℃ for 2 hours to obtain metallurgical grade Al2O3 (purity 98.6%, aluminum recovery rate 95.3%). S5, Selective recovery of magnesium: 10.5% sodium fluoride (addition amount is 1.21 times the molar amount of magnesium ions) was added to the aluminum precipitation liquid, and the mixture was stirred at 40℃ for 1.5 hours to generate MgF2 precipitate. The MgF2 filter cake and tailings were separated by pressure filtration. After washing and drying, the MgF2 filter cake was used to obtain a high-quality magnesium salt product (MgF2 purity 96.0%, magnesium recovery rate 93.1%). S6, Tailings treatment: The tailings were neutralized with lime milk to pH=7.0 and discharged in compliance with standards.

[0043] Example 7: A method for recovering valuable elements from bauxite wet desulfurization liquid. Referring to Figure 1, a method for recovering valuable elements from bauxite wet desulfurization liquid includes the following steps: S1, Pretreatment and impurity removal: Take 200 mL of bauxite wet desulfurization liquid, filter it through a ceramic membrane (pore size 80 nm) to remove unreacted slag and large particulate impurities, obtaining a clear filtrate; transfer the clear filtrate to an adjusting tank, adjust the pH to 2.9, and homogenize and stir at 300 r / min for pretreatment to obtain a homogenized filtrate for later use; S2, Targeted recovery of silicon: Add a cationic flocculant (polyvinyl chloride) to the homogenized filtrate. Aluminum chloride and polyacrylamide (mass ratio 3:1) were added at 0.08% of the filtrate mass. The mixture was stirred at 50℃ for 35 min to allow silicate ions to combine with the flocculant and form silica gel precipitate. Filtration was used to separate the silica gel filter cake and the desiliconized filtrate. The silica gel filter cake was washed three times with deionized water, dried at 105℃ for 2 h, and calcined at 580℃ for 3 h to obtain silica (SiO2 purity 98.7%, silicon recovery rate 95.4%). S3, Oxidation Precipitation to Remove Iron: Ozone (ozone concentration 92 mg / L, gas-liquid mass ratio 4:1) was introduced into the desiliconized filtrate and oxidized by stirring at 60℃ for 1 h to remove Fe from the filtrate. 2+ Completely oxidized to Fe 3+ (ORP monitored = 485mV), add 18% ammonium bicarbonate to adjust pH to 4.8, and maintain the reaction at 60℃ for 1.5h to allow Fe to... 3+Hydrolysis produces FeOOH precipitate, PAM flocculant is added, and after standing for 20 minutes, it is filtered to obtain iron slag and iron-removed filtrate. The iron slag is washed, dried, and calcined at 800℃ for 2 hours to obtain Fe2O3 (purity 97.9%, iron recovery rate 97.3%). Separation and purification of S4 and aluminum: 25% ammonia water is added to the iron-removed filtrate to adjust the pH to 6.3, and boehmite seed crystals are added (the amount added is 7.5% of the theoretical Al(OH)3 mass). Aging at 60℃ for 2.5 hours promotes Al(OH)3 crystal growth. Centrifugation separates the Al(OH)3 filter cake and the aluminum-precipitated liquid. The (OH)3 filter cake was washed three times with deionized water at 65℃ to remove adsorbed impurity ions on the surface. Then, it was transferred to a rotary kiln and calcined at 1230℃ for 2 hours to obtain metallurgical grade Al2O3 (purity 99.0%, aluminum recovery rate 96.8%). S5, Selective recovery of magnesium: 13% sodium fluoride (addition amount is 1.26 times the molar amount of magnesium ions) was added to the aluminum precipitation liquid and stirred at 50℃ for 1.5 hours to generate MgF2 precipitate. The MgF2 filter cake and tailings were separated by pressure filtration. After washing and drying, the MgF2 filter cake was used to obtain high-quality magnesium salt product (MgF2 purity 96.6%, magnesium recovery rate 94.3%). S6, Tailings treatment: The tailings were neutralized with lime milk to pH=7.0 and discharged in compliance with standards.

[0044] Example 8: A method for recovering valuable elements from bauxite wet desulfurization liquid (industrial simulation conditions). Referring to Figure 1, a method for recovering valuable elements from bauxite wet desulfurization liquid includes the following steps: S1, Pretreatment and impurity removal: Take 200 mL of bauxite wet desulfurization liquid, filter it through a ceramic membrane (80 nm pore size) to remove unreacted slag and large particulate impurities, obtaining a clear filtrate; transfer the clear filtrate to an adjusting tank, adjust the pH to 2.7, and homogenize and stir at 300 r / min (conventional industrial speed) for pretreatment, obtaining a homogenized filtrate for later use; S2, Targeted recovery of silicon: Add a cationic flocculant (polyaluminum chloride: polyacrylamide mass ratio of 3:1) to the homogenized filtrate, the amount added being equal to the filtrate mass. 0.08% of the silicate was stirred at 40℃ for 35 min to form silica gel precipitate by combining silicate ions with flocculant. The silica gel filter cake and the desiliconized filtrate were obtained by pressure filtration. The silica gel filter cake was washed three times with deionized water, dried at 105℃ for 2 h, and calcined at 580℃ for 3 h to obtain silica (SiO2 purity 98.6%, silicon recovery rate 95.2%). S3, Oxidation precipitation to remove iron: Ozone (ozone concentration 90 mg / L, gas-liquid mass ratio 4:1) was introduced into the desiliconized filtrate and oxidized by stirring at 50℃ for 1 h (industrial standard oxidation time) to remove Fe from the filtrate. 2+ Completely oxidized to Fe 3+ (ORP monitored = 475mV), add 18% ammonium bicarbonate to adjust pH to 4.7, and maintain the reaction at 50℃ for 1.5h to allow Fe to... 3+Hydrolysis produces FeOOH precipitate, PAM flocculant is added, and after standing for 20 minutes, it is filtered to obtain iron slag and filtrate after iron removal. The iron slag is washed, dried, and calcined at 800℃ for 2 hours to obtain Fe2O3 (purity 97.8%, iron recovery rate 97.2%). Separation and purification of S4 and aluminum: 25% ammonia water is added to the filtrate after iron removal to adjust the pH to 6.2, and pseudoboehmite seed crystals are added (the amount added is 6% of the theoretical Al(OH)3 mass, a commonly used industrial ratio). Aging at 60℃ for 2.5 hours promotes Al(OH)3 crystal growth. Centrifugation separates the Al(OH)3 filter cake and the liquid after aluminum precipitation. The (OH)3 filter cake was washed three times with deionized water at 65℃ to remove adsorbed impurity ions. Then, it was transferred to a rotary kiln and calcined at 1220℃ for 2 hours to obtain metallurgical grade Al2O3 (purity 98.9%, aluminum recovery rate 96.5%). S5, Selective recovery of magnesium: 12% sodium fluoride (addition amount 1.25 times the molar amount of magnesium ions) was added to the aluminum precipitation liquid, and the mixture was stirred at 50℃ for 1.5 hours (industrial precipitation time) to generate MgF2 precipitate. The MgF2 filter cake and tailings were separated by pressure filtration. After washing and drying, the MgF2 filter cake yielded a high-quality magnesium salt product (MgF2 purity 96.5%, magnesium recovery rate 94.0%). S6, Tailings treatment: The tailings were neutralized with lime milk to pH=7.0 and discharged in compliance with standards. The small amount of precipitate generated during the neutralization process was returned to the pretreatment process in step S1 to recover trace amounts of aluminum and iron elements, thereby increasing the total aluminum and iron recovery rate by about 0.8%.

[0045] In summary, the embodiments of the present invention take pretreatment accuracy, oxidation depth, and precipitation accuracy as key synergies. Under simulated industrial conditions in Example 8, the invention verified its good process robustness and industrialization potential, successfully achieving high-value-added utilization of resources and a green closed loop, providing a reliable technical example for the full-element resource utilization of complex mineral leachates.

[0046] It will be readily understood by those skilled in the art that the above-described advantageous methods can be freely combined and superimposed without conflict. The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A method for recovering valuable elements from bauxite wet desulfurization liquid, characterized in that, Includes the following steps: S1. Pretreatment and impurity removal: The bauxite wet desulfurization liquid is filtered through a ceramic membrane to remove impurities, resulting in a clear filtrate; the pH of the clear filtrate is adjusted to acidic, and after stirring evenly, a homogenized pretreatment liquid is obtained; S2. Targeted recovery of silicon: A cationic flocculant is added to the homogenized pretreatment liquid to react and form silica gel precipitate; After solid-liquid separation, a silica gel filter cake and a filtrate after silica removal were obtained. The silica filter cake is washed, dried, and calcined to obtain precipitated silica product; S3, oxidation precipitation to remove iron: ozone is introduced into the filtrate after silica removal for oxidation, removing Fe 2+ Oxidized to Fe 3+ Then ammonium bicarbonate was added to adjust the pH and generate FeOOH precipitate; After solid-liquid separation, iron slag and iron-removed filtrate were obtained; The iron slag is washed and calcined to obtain iron oxide products; S4. Aluminum Separation and Purification: Ammonia water is added to the filtrate after iron removal to adjust the pH, and seed crystals are added for aging and crystallization to obtain Al(OH)3 precipitate; after solid-liquid separation, Al(OH)3 filter cake and aluminum precipitation filtrate are obtained; the Al(OH)3 filter cake is washed and calcined to obtain metallurgical grade alumina product; S5. Selective Recovery of Magnesium: A fluorine-containing precipitant is added to the aluminum precipitation filtrate to react and generate MgF2 precipitate; after solid-liquid separation, MgF2 filter cake and tailings are obtained; the MgF2 filter cake is washed and dried to obtain MgF2 product; S6. Tailings Treatment: The tailings are neutralized and discharged after meeting the standards.

2. The method for recovering valuable elements from bauxite wet desulfurization liquid according to claim 1, characterized in that, In step S1, the pore size of the ceramic membrane is 50nm-100nm, and the pH is adjusted to 2.5-3.

0.

3. The method for recovering valuable elements from bauxite wet desulfurization liquid according to claim 1, characterized in that, In step S2, the cationic flocculant is a mixture of polyaluminum chloride and polyacrylamide in a mass ratio of 3:

1. The amount of cationic flocculant added is 0.05%-0.1% of the mass of the homogenized pretreatment liquid. The reaction temperature is 40℃-50℃, the reaction time is 30min-60min, the calcination temperature is 550℃-600℃, and the calcination time is 3h-5h.

4. The method for recovering valuable elements from bauxite wet desulfurization liquid according to claim 3, characterized in that, In step S2, the purity of SiO2 in the obtained silica is ≥98%, and the recovery rate of silicon is not less than 94%.

5. The method for recovering valuable elements from bauxite wet desulfurization liquid according to claim 1, characterized in that, In step S3, the ozone concentration is 75 mg / L-100 mg / L, the gas-liquid mass ratio is (3-5):1, the oxidation reaction temperature is 50℃-60℃, and the oxidation endpoint ORP ≥ 450 mV; the addition of ammonium bicarbonate to adjust the pH and generate FeOOH precipitate includes: adjusting the pH to 4.5-5.0 with 15%-20% ammonium bicarbonate, and maintaining the reaction at 50℃-60℃ for 1.5-2 hours to allow FeOOH to precipitate. 3+ Hydrolysis produces FeOOH precipitate.

6. The method for recovering valuable elements from bauxite wet desulfurization liquid according to claim 5, characterized in that, The iron oxide product is Fe2O3, with a purity of not less than 97% and an iron recovery rate of not less than 96%.

7. The method for recovering valuable elements from bauxite wet desulfurization liquid according to claim 1, characterized in that, In step S4, the ammonia water has a mass fraction of 20%-30%, and the pH is adjusted to 6.0-6.5; the seed crystal is boehmite, and its addition amount is 5%-8% of the theoretical Al(OH)3 mass; the aging temperature is 50℃-60℃, and the aging time is 2.5h-3h; the calcination temperature is 1200℃-1250℃, and the calcination time is 2h-3h.

8. The method for recovering valuable elements from bauxite wet desulfurization liquid according to claim 7, characterized in that, The purity of Al2O3 in the metallurgical grade alumina product is not less than 98.5%, and the aluminum recovery rate is not less than 95%.

9. The method for recovering valuable elements from bauxite wet desulfurization liquid according to claim 1, characterized in that, In step S5, the fluorine-containing precipitant is a sodium fluoride solution, and its addition amount is 1.2-1.3 times the molar amount of magnesium ions in the filtrate after aluminum precipitation; the reaction temperature is 40℃-50℃, and the reaction time is 1.5h-2h.

10. The method for recovering valuable elements from bauxite wet desulfurization liquid according to claim 9, characterized in that, The MgF2 product has a purity of not less than 96% and a magnesium recovery rate of not less than 93%.

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