Method for synergetic recycling of Ga, Si and Al in brown fused alumina smoke and in-situ circulation of K

Abstract

The invention provides a method for synergetic recycling of Ga, Si and Al in brown fused alumina smoke and in-situ circulation of K, and belongs to the field of high-value utilization of industrial solid waste. According to the method, gallium is selectively extracted through a potassium hydroxide leaching system, and silicon, aluminum and potassium in smoke are synchronously dissolved out; the adsorption and enrichment of gallium and the separation of silicon and potassium are realized by adopting oxalic acid precipitation-boiling water washing, and high-purity silicon dioxide (the purity is greater than 98%) and a gallium-rich solution are obtained through acid leaching purification; and aluminum is deeply recycled and a solution system is reconstructed by combining an oxidation-carbonation process, and finally closed-loop circulation of a potassium resource is realized through oxalate oxygenolysis and causticization regeneration. The method realizes efficient recovery of four components in brown aluminum oxide smoke dust, solves the bottleneck problems of difficult liquid-solid separation caused by acid corrosion and silica gel flocculation, high cost caused by high consumption of a gallium extraction reagent, low total recycling rate of solid waste brown aluminum oxide smoke dust and the like in the prior art, and has remarkable economic and environmental benefits.

Description

Technical Field

[0001] The invention relates to the technical field of resource utilization of industrial solid waste, and specifically to a comprehensive recovery method for simultaneously extracting high-value metal gallium, purifying silicon dioxide, purifying aluminum oxide and realizing internal circulation of potassium resources from brown corundum smoke. Background Art

[0002] Brown corundum dust is solid dust collected by dust collecting equipment during the smelting process of brown corundum in electric arc furnace. It is currently mainly disposed of as solid waste in the form of landfill or stockpile. 2 O 3 0.08%-0.25%), silicon (SiO 2 35%-50%), potassium (K 2 O 15%-20%), aluminum (Al 2 O 3 18%-25%) and other ingredients. With the development of new energy vehicles, 5G, photovoltaics, and semiconductor industries in recent years, the market demand for gallium continues to increase, and the extraction of gallium from brown corundum dust has attracted attention.

[0003] At present, the main gallium extraction technology research in the laboratory is high-acidity sulfuric acid leaching, sulfuric acid and hydrofluoric acid mixed acid leaching, and sodium hydroxide strong base leaching. When leaching gallium with sulfuric acid, concentrated acid and hydrofluoric acid are highly corrosive to the equipment, and the colloidal silica formed during the leaching process makes filtration difficult; Patent ZL 202111122377.0 recovers gallium through roasting activation-acid leaching, which can effectively control the dissolution of silicon in the raw material, but the energy consumption is high and the silicon and potassium in the brown corundum dust are not effectively separated and extracted, resulting in a waste of resources. In short, the total resource utilization rate of the current brown corundum dust gallium extraction technology is not high, resulting in the failure to effectively dispose of solid waste while extracting gallium.

[0004] Based on this, it is an urgent technical problem to provide a method for efficiently recovering multiple components in brown corundum dust, overcoming the defects of existing solutions such as acid corrosion, silica gel flocculation leading to difficulty in liquid-solid separation, high cost due to large consumption of gallium extraction reagents, and low overall resource utilization rate of solid waste brown corundum dust. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies of the prior art and provide a comprehensive recovery method for simultaneously extracting high-value metallic gallium, purifying silicon dioxide, purifying aluminum oxide and realizing the internal circulation of potassium resources from brown corundum smoke.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solution: a method for the coordinated resource recovery of Ga, Si, Al and in-situ circulation of K in brown corundum dust is provided, comprising the following steps: S1, mixing brown corundum dust with potassium hydroxide solution, and performing leaching reaction to obtain a leaching solution; S2, adding oxalic acid to the leachate to adjust the pH, and then performing solid-liquid separation to obtain filtrate A and precipitate A, and washing the precipitate A with boiling water to obtain washing liquid A and precipitate B; the filtrate A is a potassium oxalate solution containing aluminum; and the precipitate B is a gallium-rich amorphous silica precipitate; S3, subjecting the precipitate B to acid leaching to obtain a gallium-containing solution and high-purity silicon dioxide, and recovering metallic gallium from the gallium-containing solution by extraction-electrolysis; subjecting the filtrate A to oxidation and carbonation treatment to obtain an aluminum hydroxide precipitate and a filtrate B, and subjecting the aluminum hydroxide precipitate to boiling water washing to obtain a washing solution B; S4, the washing liquid A in step S2, the filtrate B in step S3 and the washing liquid B are mixed, subjected to oxidation treatment and causticization treatment, and then filtered and evaporated to concentrate to obtain a potassium hydroxide solution; the obtained potassium hydroxide solution is returned to step S1 for circulation.

[0007] The overall idea and inventive principle of the present invention are as follows: In order to solve the problems of high cost caused by large consumption of leaching agent for gallium extraction from brown corundum dust, low overall resource utilization rate of dust caused by waste of silicon, aluminum and potassium resources, the present invention provides a comprehensive recovery method for simultaneously extracting high-value metal gallium, purifying silicon dioxide, purifying aluminum oxide and realizing internal circulation of potassium resources from brown corundum dust. Compared with the existing scheme, the main improvements of the present invention are reflected in the following two aspects: On the one hand, the effective separation of Si and Al is achieved by "oxalation-oxidation-carbonation treatment". In step S2, the gallium-containing leachate is first subjected to oxalation treatment, which can reduce the pH of the gallium-containing leachate, thereby achieving the co-precipitation of Si and Ga ions in the solution, and avoiding the precipitation of Al ions based on the characteristics that oxalate ions easily form stable complexes with Al ions, thereby achieving the separation of Si and Ga from Al. In the subsequent step S3, the filtrate A (aluminum-containing potassium oxalate solution) is subjected to oxidation treatment to destroy the oxalate ions in the filtrate A, so that Al is converted into aluminum hydroxide and precipitated. Considering that the high pH of the solution after oxidation treatment is not conducive to the precipitation of Al ions, the present invention also uses carbonation treatment as a supplementary means of oxidation to further reduce the pH value of the solution, promote the thorough precipitation of Al in the solution, and achieve the effective separation of Si and Al.

[0008] On the other hand, a multi-component stepwise separation path is established under the potassium hydroxide system to realize the in-situ circulation of potassium. In the leaching reaction of step S1, the present invention uses potassium hydroxide as the alkali solution. There are two main reasons: First, the raw materials in the brown corundum dust always contain K (K 2O content is about ~20%), potassium hydroxide is used for leaching reaction, K in the raw material is dissolved (leaching rate is 50%-70%), which can make up for the loss of leaching agent in the whole process, and no additional alkali solution is needed in the subsequent circulation treatment, and the K resources contained in the raw material itself are fully utilized. Secondly, potassium hydroxide is used as alkali solution to leach the raw material, and Al, Si, and K ions in the solution system will not form precipitates, so the leaching rate of Si can be significantly improved, which provides the necessary premise for the efficient and high-value utilization of Si resources in the raw material.

[0009] Furthermore, in step S1, the concentration of the potassium hydroxide solution is 180-250 g / L, the mass volume ratio of brown corundum dust to potassium hydroxide solution is 1: (5-20) g / mL, the temperature of the leaching reaction is 80-175°C, and the time is 40-90 min. Preferably, the concentration of the potassium hydroxide solution is 200-230 g / L, the temperature of the leaching reaction is 95-175°C, and under this leaching condition, the leaching rate of gallium is more than 95%. At the same time, with the increase of temperature, the leaching rate of silicon continues to increase. When the temperature is 175°C, the silicon leaching rate can reach ~60%.

[0010] The existing method usually uses sodium hydroxide as a leaching agent to carry out alkaline leaching treatment on brown corundum dust. Aluminum, silicon, and potassium will leach out of the solution together with gallium. In the subsequent process of separating Si and Al from the solution, Si, Al, K and Na in the leaching agent will form a potassium / sodium aluminosilicate precipitate with a stable structure. This precipitate is difficult to be effectively utilized, and also leads to the loss of Si, Al, and K resources and a large loss of the leaching agent NaOH solution. In addition, when leaching with NaOH solution, the formation of sodium aluminosilicate precipitate also leads to a low dissolution rate of Si in the raw material (Si leaching rate <20%), and Si in the raw material cannot be effectively separated and used at a high value.

[0011] In the present invention, after the treatment in step S1, the gallium leaching rate of each element in the brown corundum fume is calculated by weight percentage, the potassium leaching rate is greater than 95%, the silicon leaching rate is 35%-60%, and the aluminum leaching rate is 8%-15%, which provides the necessary prerequisite for the subsequent separation and preparation of high-purity silicon oxide and aluminum oxide.

[0012] Furthermore, in step S2, oxalic acid is added to the leachate to adjust the pH to 7.5-11.5. In the present invention, after the treatment in step S2, gallium is enriched in the amorphous silicon dioxide precipitate, the silicon precipitation rate is 50%-100%, and the gallium precipitation rate is 80%-100%.

[0013] In the present invention, the following three factors are mainly considered when using oxalic acid to treat the leachate: (1) oxalate can form a stable complex with Al ions and stably exist in the solution, but does not form a complex with silicon and gallium ions, thereby achieving the selective separation of Al from Si and Ga; (2) oxalic acid is used to adjust the pH value of the leachate to reduce the alkalinity of the solution, so that the silica in the solution aggregates and precipitates. Since oxalic acid is a weak acid, the local pH will not drop too fast during adjustment, ensuring the smooth progress of the precipitation process; (3) Compared with other acids, oxalate can be easily converted into CO 2 gas, or converted into CO 3 2- , the gas can directly overflow the reaction system, CO 3 2- Then, the subsequent addition of CaO or Ca(OH) 3 Causticization reaction occurs, making K 2 CO 3 Convert KOH to pave the way for subsequent K recycling.

[0014] Furthermore, in step S2, oxalic acid is used to reduce the pH of the solution, so that the stability of silicate in the solution is reduced, and silicate polymerizes and flocculates to form a colloid, which adsorbs gallium ions in the solution, so that Ga and Si components in the solution coprecipitate. The present invention increases the gallium enrichment concentration by more than 3 times through the synergistic mechanism of oxalic acid precipitation and adsorption.

[0015] Furthermore, in step S2, it is preferred to add fine solid oxalic acid particles to avoid introducing too much water into the system and affecting the subsequent circulation balance. At the same time, the oxalic acid solid needs to be slowly added to the leachate and stirred evenly to prevent the local pH from decreasing rapidly. Preferably, the pH of the solution is adjusted to 8.0-9.5 using oxalic acid to ensure a higher comprehensive recovery rate of both Si and Ga.

[0016] Furthermore, in step S3, the acid leaching treatment uses hydrochloric acid with a concentration of 2.5-6 mol / L, and the obtained gallium-containing solution is a gallium chloride solution.

[0017] Preferably, in step S2 and step S3, when the pH of the oxalic acid solution is controlled to be 8.0-9.5, the boiling water and the precipitate are washed at least 3 times at a solid-liquid ratio of 1:1, and the concentration of hydrochloric acid for acid leaching is 4.6-6 mol / L, the purity of the obtained high-purity silicon dioxide is not less than 98%.

[0018] Further, in step S3, the raw material used in the oxidation treatment is hydrogen peroxide, the molar ratio of hydrogen peroxide to oxalate in filtrate A is 1.2-1.5:1, and the temperature of the oxidation treatment is 60-90° C. In this step, the oxalate in the solution is oxidized by hydrogen peroxide, the complex structure of oxalate and aluminum ions is destroyed, the Al ions in the solution become unstable, and aluminum hydroxide precipitation is formed. By increasing the oxidation treatment temperature to 60-90° C., it helps to accelerate the oxidation reaction.

[0019] Furthermore, in step S3, the carbonation treatment is performed by introducing carbon dioxide gas until no new precipitation is generated, and the introduction rate of carbon dioxide is 0.5-1.5 L / min.

[0020] In step S3 of the present invention, the oxidation treatment destroys the complex structure of oxalate and aluminum ions in the filtrate A, and the carbon dioxide gas introduced subsequently further reduces the pH of the system and fully precipitates aluminum, with an aluminum precipitation rate of nearly 100%. The potassium salt is recovered in the washing solution B by washing the aluminum hydroxide precipitate with boiling water.

[0021] Preferably, in step S3, hydrogen peroxide is added to the supernatant until no obvious precipitation is produced, and then CO is introduced. 2 When the pH value is 7.0-7.5, the aluminum precipitation rate can be no less than 99.7%.

[0022] Furthermore, in step S4, the oxidation treatment is performed by adding hydrogen peroxide to the mixed solution.

[0023] Furthermore, in step S4, the causticizing treatment is carried out by adding calcium oxide or calcium hydroxide to the product obtained by the oxidation treatment; the temperature of the causticizing treatment is 80-100° C., and the time is 1-2 hours.

[0024] In step S4 of the present invention, the addition of hydrogen peroxide can oxidatively decompose oxalate, and convert it into different products according to the pH of the solution system: when the pH is high and the solution is alkaline, CO is generated. 3 2- , that is, K 2 CO 3 When the pH is low, it is converted into CO 2 and OH - , that is, KOH is obtained. In the actual treatment process, the solution system is often weakly alkaline, K 2 CO 3 Coexist with KOH, so CaO or Ca(OH) needs to be added 2 K 2 CO 3 It is converted into KOH to achieve complete causticization, and finally a KOH solution is obtained which can be returned to the leaching process for recycling.

[0025] Furthermore, in the method, the recycling rate of potassium is higher than 90%. The recycling rate of potassium here refers only to the K in the leaching agent potassium hydroxide in step S1, and does not include the K leached in the raw material. By calculation, for every 100g of brown corundum dust processed, 8.25-11.55g of K in the raw material is leached, and the leaching agent KOH is calculated at a concentration of 200g / L, and the K loss in the whole process leaching agent KOH is less than 6.95g. Therefore, in the method provided by the present invention, the potassium leached from the raw material is sufficient to supplement the loss of K in the leaching agent, and potassium hydroxide does not need to be re-input from the outside in the subsequent treatment, which can significantly reduce the processing cost of brown corundum dust, solve the problem of high leaching agent concentration and difficulty in recycling in the existing scheme, and has significant economic benefits.

[0026] In addition, the excess KOH recovered in step S4 can also be used as a stripping agent for subsequent extraction and purification and as an electrolyte for subsequent electrodeposition.

[0027] Furthermore, the amount of elements (including Si, Al, K, and Ga) effectively extracted and converted into high value in the brown corundum dust treated by the above method is counted, and the proportion of the above elements to the total weight of the raw material is calculated. According to calculations, in the method for the coordinated resource utilization of Ga, Si, and Al in the brown corundum dust and the in-situ recycling of K provided by the present invention, the overall resource utilization rate is greater than 50%.

[0028] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides a method for the coordinated resource utilization of Ga, Si, and Al and the in-situ circulation of K in brown corundum dust, establishes a multi-component step-by-step separation path under a potassium hydroxide system, realizes the selective enrichment of gallium and the simultaneous leaching of silicon, aluminum, and potassium, with a gallium leaching rate of >95% and an aluminum precipitation rate of nearly 100%. The gallium enrichment concentration is increased by more than 3 times through the synergistic mechanism of oxalic acid precipitation and adsorption, and at the same time, oxalic acid precipitation and oxidation-carbonation precipitation are combined to efficiently separate gallium-silicon-potassium-aluminum. The potassium resource is circulated in a closed loop, and the potassium recycling rate exceeds 90%. The K resource in the brown corundum dust raw material can completely compensate for the loss of the leaching agent potassium hydroxide, greatly reducing the leaching agent consumption and cost.

[0029] (2) The present invention provides a method for the coordinated resource recovery of Ga, Si, Al and in-situ circulation of K in brown corundum dust, which realizes the efficient recovery of the four components in brown corundum dust, solves the bottleneck problems in the existing schemes such as acid corrosion, silica gel flocculation leading to difficulty in liquid-solid separation, high cost due to large consumption of gallium extraction reagents, and low overall resource recovery rate of solid waste brown corundum dust. The overall resource recovery rate of the present invention is greater than 50%, which has significant economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1A schematic flow chart of a method for the coordinated resource recovery of Ga, Si, Al and in-situ circulation of K in brown corundum dust provided by an embodiment of the present invention; Figure 2 The leaching rates of Ga and Si obtained by leaching with potassium hydroxide at different temperatures in the embodiments of the present invention; Figure 3 The XRD patterns of the precipitates obtained at the oxalation endpoint pH values ​​of 11.5 and 7.5 in the examples of the present invention are shown. DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0033] The embodiment of the present invention provides a method for the coordinated resource recovery of Ga, Si, Al and in-situ circulation of K in brown corundum dust, and the schematic diagram of the process is shown in FIG. Figure 1 As shown, the following steps are included: Step 1: Potassium Hydroxide Leaching The brown corundum dust is mixed with potassium hydroxide solution, and subjected to leaching reaction to obtain a leaching solution; wherein the concentration of the potassium hydroxide solution is 180-250 g / L, the mass volume ratio of the brown corundum dust to the potassium hydroxide solution is 1: (5-20) g / mL, the leaching reaction temperature is 80-175°C, and the time is 40-90 minutes.

[0034] Figure 2 is the leaching rate of Ga and Si obtained by potassium hydroxide leaching at different temperatures. Figure 2 It can be seen that when potassium hydroxide is leached, Al, Si, and K ions in the solution system will not form precipitates, so a very high Si leaching rate can be obtained, which provides a prerequisite for the efficient and high-value utilization of Si resources in the raw materials.

[0035] Step 2: Oxalic acid precipitation Oxalic acid is added to the leachate to adjust the pH to 7.5-11.5, and then solid-liquid separation is performed to obtain filtrate A and precipitate A, and the precipitate A is washed with boiling water at least 3 times to obtain washing liquid A and precipitate B; the filtrate A is an aluminum-containing potassium oxalate solution; and the precipitate B is a gallium-rich amorphous silica precipitate.

[0036] Figure 3The XRD patterns of the precipitates obtained at the end points of oxalic acid treatment at pH 11.5 and 7.5 are shown in Figure 2. Figure 3 It can be seen that the oxalic acid treatment results in a mixed precipitate of potassium oxalate and silicic acid. Combining the component analysis of the precipitate, it can be seen that Ga exists in the silicic acid precipitate, while Al 2 O 3 The content is very low (1%-3%), which proves that the present invention uses oxalic acid treatment to achieve effective separation of Si and Al.

[0037] Step 3 (1): Acid extraction of gallium and purification of silica The precipitate B is subjected to acid leaching treatment using hydrochloric acid with a concentration of 2.5-6 mol / L to obtain a gallium chloride solution and high-purity silicon dioxide with a purity of not less than 98%, and metallic gallium is recovered from the gallium chloride solution by extraction-electrolysis; Step 3 (2): Oxidation-carbonation precipitation The filtrate A is subjected to oxidation treatment and carbonation treatment to obtain aluminum hydroxide precipitate and filtrate B; the aluminum hydroxide precipitate is washed with boiling water to obtain washing solution B. The raw material used in the oxidation treatment is hydrogen peroxide, the molar ratio of hydrogen peroxide to oxalate in the filtrate A is 1.2-1.5:1, and the temperature of the oxidation treatment is 60-90°C; the carbonation treatment is carried out by introducing carbon dioxide gas until no new precipitate is generated, and the introduction rate of carbon dioxide is 0.5-1.5 L / min.

[0038] Step 4: Potassium resource internal circulation The washing liquid A in step 2, the filtrate B in step 3 and the washing liquid B are mixed, hydrogen peroxide is added to the mixed liquid for oxidation treatment, and then calcium oxide or calcium hydroxide is added to the product obtained by the oxidation treatment for caustic treatment, the temperature of the caustic treatment is 80-100° C., and the time is 1-2 hours; then filtered and evaporated to obtain a potassium hydroxide solution; the obtained potassium hydroxide solution is returned to step 1 for circulation.

[0039] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0040] The main reaction conditions and parameters involved in the method for the coordinated resource recovery of Ga, Si, Al and in-situ circulation of K in brown corundum dust provided in Examples 1-3 of the present invention are shown in Table 1. The leaching rate, precipitation rate and recovery rate are all expressed in weight percentage of the elements.

[0041] Table 1

[0042] Example 1 This embodiment provides a method for the coordinated resource recovery of Ga, Si, and Al and the in-situ circulation of K in brown corundum dust, comprising the following steps: 1. Potassium hydroxide leaching: weigh 30g brown corundum dust (containing Ga 2 O 3 0.18%, SiO 2 42%, K 2 O 18%, Al 2 O 3 20%), add 300 mL of 200 g / L potassium hydroxide solution, make the liquid-solid ratio of potassium hydroxide solution to brown corundum dust be 10:1 mL / g, and react at 130°C. After 60 minutes, take out the slurry and filter it to obtain gallium-containing alkaline leaching solution and residue. After filtration, the gallium leaching rate was measured to be 99.2%, the potassium leaching rate was 65%, the silicon leaching rate was 40%, and the aluminum leaching rate was 10%.

[0043] 2. Oxalic acid precipitation: Powdered oxalic acid was slowly added to the leachate while stirring, and the pH was adjusted to 9.5 to generate a mixed precipitate (precipitate A) of gallium-containing silicon slag (Ga content 4600 ppm) and potassium oxalate, as well as filtrate A. After testing, the silicon precipitation rate was 92% and the gallium precipitation rate was 85%. Precipitate A was washed 3 times with boiling water to obtain a potassium oxalate solution (washing liquid A) and a gallium-rich silicon dioxide precipitate (precipitate B) (Ga content 6500 ppm).

[0044] 3. Acid extraction of gallium and purification of silicon: The gallium-rich silica precipitate obtained in step 2 is washed with 6 mol / L hydrochloric acid to dissolve the gallium to obtain silica with a purity of 98.5%; the gallium-containing solution is extracted and electrolyzed to recover metallic gallium, with a gallium recovery rate of 94%.

[0045] 4. Oxidation-carbonation precipitation: Add hydrogen peroxide (the amount added is 1.3 times the molar amount of oxalate) to filtrate A and heat to 80°C. After no bubbles are released, introduce CO 2 (rate 1.0 L / min), aluminum hydroxide precipitate and filtrate B were generated. After testing, the aluminum precipitation rate was 99.8%. The aluminum hydroxide precipitate was washed with boiling water to obtain washing solution B and purified aluminum hydroxide precipitate.

[0046] 5. Internal circulation of potassium resources: Washing liquid A, filtrate B and washing liquid B are combined, hydrogen peroxide is added to oxidize and decompose oxalate, and a mixed solution of potassium hydroxide and a small amount of potassium carbonate is generated. Calcium hydroxide is added to thoroughly causticize the solution to generate potassium hydroxide solution and return it to the leaching process. The potassium recycling rate is 93%.

[0047] Example 2 This embodiment provides a method for the coordinated resource recovery of Ga, Si, and Al and the in-situ circulation of K in brown corundum dust, comprising the following steps: 1. Alkaline leaching: weigh 30g brown corundum dust (containing Ga 2 O 3 0.18%, SiO 2 42%, K 2 O 18%, Al 2 O 3 20%), add 300 mL of 220 g / L potassium hydroxide solution, make the liquid-solid ratio of potassium hydroxide solution to brown corundum dust be 10:1 mL / g, and react at 150°C for 1 hour. After filtration, gallium-containing alkaline leaching solution and residue were obtained. After testing, the gallium leaching rate was 99.5%, the potassium leaching rate was 69%, the silicon leaching rate was 55%, and the aluminum leaching rate was 15%.

[0048] 2. Oxalic acid precipitation: Slowly add oxalic acid to the leaching solution, adjust the pH to 7.8, and generate a mixed precipitate (precipitate A) of gallium-containing silicon slag (Ga content 3500 ppm) and potassium oxalate, as well as filtrate A. After testing, the silicon precipitation rate was 99%, and the gallium precipitation rate was 99%; the precipitate A was washed with boiling water 3 times to obtain potassium oxalate solution (washing liquid A) and gallium-rich silicon dioxide (precipitate B) (Ga content 4700ppm).

[0049] 3. Gallium extraction by acid method: The gallium-rich silica obtained in step 2 is washed with 6 mol / L hydrochloric acid to dissolve the gallium to obtain silica. The purity of the silica after purification reaches 98.7%. The gallium-containing solution is extracted and electrolyzed to recover metallic gallium, and the gallium recovery rate is 94.5%.

[0050] 4. Oxidation-carbonation: Add hydrogen peroxide (the amount added is 1.4 times the molar amount of oxalate) to filtrate A, heat to 80°C and then pass CO 2 (rate 1.0 L / min), aluminum hydroxide precipitate and filtrate B were generated. After testing, the aluminum precipitation rate was 99.9%; the aluminum hydroxide precipitate was washed with boiling water to obtain purified aluminum hydroxide precipitate and washing solution B.

[0051] 5. Potassium circulation: Washing liquid A, filtrate B and washing liquid B are combined, hydrogen peroxide is added to oxidize and decompose oxalate, a mixture of potassium hydroxide and a small amount of potassium carbonate is generated, and then calcium hydroxide is added for causticization to generate potassium hydroxide solution which is returned to the leaching process. The potassium hydroxide solution after causticization is returned to the leaching process, and the potassium recycling rate is 96%.

[0052] Example 3 This embodiment provides a method for the coordinated resource recovery of Ga, Si, and Al and the in-situ circulation of K in brown corundum dust, comprising the following steps: 1. Alkaline leaching: weigh 30g brown corundum dust (containing Ga 2 O 3 0.18%, SiO 2 42%, K 2O 18%, Al 2 O 3 20%), add 300 mL of 180 g / L potassium hydroxide solution, make the liquid-solid ratio of potassium hydroxide solution to brown corundum dust 10:1 mL / g, and react at 95°C for 70 minutes. After filtration, gallium-containing alkaline leaching solution and residue were obtained. After testing, the gallium leaching rate was 96.42%, the potassium leaching rate was 50%, the silicon leaching rate was 31%, and the aluminum leaching rate was 9.5%.

[0053] 2. Oxalic acid precipitation: Slowly add oxalic acid to the leaching solution, adjust the pH to 10.0, and generate a mixed precipitate (precipitate A) of gallium-containing silicon slag (Ga content 4800 ppm) and potassium oxalate, as well as filtrate A. After testing, the silicon precipitation rate was 80%, and the gallium precipitation rate was 73%; the precipitate A was washed with boiling water 3 times to obtain potassium oxalate solution (washing liquid A) and gallium-rich silicon dioxide (precipitate B) (Ga content 6720ppm).

[0054] 3. Gallium extraction by acid method: The gallium-rich silica obtained in step 2 is washed with 6 mol / L hydrochloric acid to dissolve the gallium to obtain silica, and the purity of the silica after purification reaches 99.0%; the gallium-containing solution is extracted and electrolyzed to recover metallic gallium, and the gallium recovery rate is 96%.

[0055] 4. Oxidation-carbonation: Add hydrogen peroxide (the amount added is 1.1 times the molar amount of oxalate) to filtrate A, heat to 80°C and then pass CO 2 (rate 1.2 L / min), aluminum hydroxide precipitate and filtrate B were generated. After testing, the aluminum precipitation rate was 99.7%; the aluminum hydroxide precipitate was washed with boiling water to obtain purified aluminum hydroxide precipitate and washing solution B.

[0056] 5. Potassium circulation: Washing liquid A, filtrate B and washing liquid B are combined, hydrogen peroxide is added to oxidize and decompose oxalate, a mixture of potassium hydroxide and a small amount of potassium carbonate is generated, and then calcium hydroxide is added for causticization to generate potassium hydroxide solution which is returned to the leaching process. The potassium hydroxide solution after causticization is returned to the leaching process, and the potassium circulation rate is 92%.

[0057] In summary, the present invention provides a method for the coordinated resource utilization of Ga, Si, and Al and the in-situ circulation of K in brown corundum dust, establishes a multi-component step-by-step separation path under a potassium hydroxide system, and increases the gallium enrichment concentration by more than 3 times through the synergistic mechanism of oxalic acid precipitation and adsorption; the potassium recycling rate exceeds 90%, greatly reducing the consumption and cost of leaching agents. The present invention can efficiently recycle multiple components in brown corundum dust, with an overall resource utilization rate of >50%, a gallium leaching rate of >95%, an aluminum precipitation rate of nearly 100%, and a silicon dioxide purity of >98%. It overcomes the problems of acid corrosion, silica gel flocculation leading to difficulty in liquid-solid separation, and high cost caused by large consumption of gallium extraction reagents in existing solutions, and provides a new solution for the high-value resource utilization of solid waste brown corundum dust.

[0058] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the specification of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for the coordinated resource recovery of Ga, Si, Al and in-situ circulation of K in brown corundum dust, characterized in that: The following steps are involved: S1, mixing brown corundum dust with potassium hydroxide solution, and performing leaching reaction to obtain a leaching solution; S2, adding oxalic acid to the leachate to adjust the pH, and then performing solid-liquid separation to obtain filtrate A and precipitate A, and washing the precipitate A with boiling water to obtain washing liquid A and precipitate B; the filtrate A is a potassium oxalate solution containing aluminum; The precipitate B is a gallium-rich amorphous silicon dioxide precipitate; S3, subjecting the precipitate B to acid leaching to obtain a gallium-containing solution and high-purity silicon dioxide, and recovering metallic gallium from the gallium-containing solution by extraction-electrolysis; subjecting the filtrate A to oxidation and carbonation treatment to obtain an aluminum hydroxide precipitate and a filtrate B, and subjecting the aluminum hydroxide precipitate to boiling water washing to obtain a washing solution B; S4, mixing the washing liquid A in step S2, the filtrate B in step S3 and the washing liquid B, subjecting the mixture to oxidation treatment and causticization treatment, and then filtering and evaporating and concentrating to obtain a potassium hydroxide solution; The obtained potassium hydroxide solution is returned to step S1 for circulation.

2. The method according to claim 1, characterized in that In step S1, the concentration of the potassium hydroxide solution is 180-250 g / L, the mass volume ratio of brown corundum dust to the potassium hydroxide solution is 1: (5-20) g / mL, the temperature of the leaching reaction is 80-175° C., and the time is 40-90 min.

3. The method according to claim 1, characterized in that In step S2, oxalic acid is added to the leaching solution to adjust the pH to 7.5-11.

5.

4. The method according to claim 1, characterized in that In step S3, the acid leaching treatment uses hydrochloric acid with a concentration of 2.5-6 mol / L, and the obtained gallium-containing solution is a gallium chloride solution.

5. The method according to claim 1, characterized in that In step S3, the purity of the high-purity silicon dioxide is not less than 98wt.%.

6. The method according to claim 1, characterized in that In step S3, the raw material used for the oxidation treatment is hydrogen peroxide, the molar ratio of hydrogen peroxide to oxalate in filtrate A is 1.2-1.5:1, and the temperature of the oxidation treatment is 60-90°C.

7. The method according to claim 1, characterized in that In step S3, the carbonation treatment is performed by introducing carbon dioxide gas until no new precipitation is generated, and the introduction rate of carbon dioxide is 0.5-1.5 L / min.

8. The method according to claim 1, characterized in that In step S4, the oxidation treatment is performed by adding hydrogen peroxide to the mixed solution.

9. The method according to claim 1, characterized in that: In step S4, the causticizing treatment is carried out by adding calcium oxide or calcium hydroxide to the product obtained by the oxidation treatment; the temperature of the causticizing treatment is 80-100° C. and the time is 1-2 hours.

10. The method according to claim 1, characterized in that In the method, the recycling rate of potassium is higher than 90%.

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