Extraction method of fluorine resource in aluminum-containing electrolyte waste

Abstract

The invention relates to a method for extracting fluorine resources in aluminum-containing electrolyte waste, and belongs to the technical field of aluminum-containing electrolyte waste. The aluminum-containing electrolyte waste contains fluorine-containing minerals, and the method comprises the following steps: under the condition of microwave dissociation, mixing the aluminum-containing electrolyte waste, a catalyst and an acidic substance, so that the aluminum-containing electrolyte waste and the acidic substance are subjected to a chemical reaction to obtain first slurry; wherein the catalyst is a microwave dissociation additive with a surface activation catalysis effect. Carrying out solid-liquid separation on the first slurry to obtain a liquid substance; and mixing the liquid substance with an aluminum precipitation additive, so that the liquid substance is subjected to a precipitation reaction, and second slurry containing aluminum fluoride is obtained. According to the embodiment of the invention, specific selective dissociation of microwaves is utilized, and fluorine-containing minerals of the aluminum-containing electrolyte waste are efficiently dissociated under the synergistic promotion dissociation action of the microwave dissociation additive and the acidic material, so that subsequent efficient conversion of aluminum fluoride is ensured, and the purity of an aluminum fluoride product can reach 95% or above.

Description

Technical Field

[0001] The present application relates to the technical field of aluminum-containing electrolyte waste, and in particular to a method for extracting fluorine resources from aluminum-containing electrolyte waste. Background Art

[0002] During the aluminum electrolysis process, aluminum fluoride or fluorine-loaded aluminum oxide must be continuously added to balance the increase in the electrolyte molecular ratio caused by the sodium content of industrial alumina, resulting in an increase in the electrolyte in the electrolytic cell. The regenerated electrolytes and salvaged electrolytes produced during the treatment of the "three wastes" of aluminum electrolysis are constantly accumulating due to the current national production capacity restrictions. About 10kg of surplus electrolyte is produced for each ton of aluminum produced. Based on this calculation, my country's annual production of surplus electrolyte content is about 370,000 tons. The large amount of idle electrolytes not only causes a waste of resources, but also occupies a large amount of storage space, which has become an important issue that aluminum electrolysis companies cannot ignore.

[0003] At present, the leaching rate of fluorine in aluminum-containing electrolyte waste using acid and (or) aluminum salt is low, especially in the low dissociation rate of cryolite and other fluorides in aluminum-containing electrolyte waste, and the leached residue contains a large amount of cryolite. Alternatively, the aluminum-containing electrolyte waste is roasted at high temperature for a long time using microwaves to recover fluorine, which has high energy consumption, great corrosion to equipment, and problems in the treatment of fluorine-containing gases, or long-term microwave hydrothermal leaching, which has high energy consumption and is not conducive to large-scale production. Summary of the invention

[0004] The present application provides a method for extracting fluorine resources from aluminum-containing electrolyte waste to solve the following technical problem: how to improve the separation efficiency of fluorine resources from aluminum-containing electrolyte waste.

[0005] In a first aspect, an embodiment of the present application provides a method for extracting fluorine resources from aluminum-containing electrolyte waste, wherein the aluminum-containing electrolyte waste contains fluorine-containing minerals, and the method comprises:

[0006] Under microwave dissociation conditions, aluminum-containing electrolyte waste, a catalyst and an acidic substance are mixed to allow the aluminum-containing electrolyte waste and the acidic substance to undergo a chemical reaction to obtain a first slurry; wherein the catalyst is a microwave dissociation additive having a surface activated catalytic effect.

[0007] Optionally, the microwave dissociation additive includes at least one of the following: fluorotitanic acid, strontium chloride, strontium sulfate, and lanthanum carbonate.

[0008] Optionally, the acidic substance includes at least one of the following: an inorganic acid and an acidic aluminum salt.

[0009] Optionally, the weight of the microwave dissociation additive is 0.01‰ to 0.1‰ of the weight of the aluminum-containing electrolyte waste; and / or,

[0010] The weight of the acidic substance is 1.5 to 2.5 times the weight of the aluminum-containing electrolyte waste.

[0011] Optionally, the process parameters of the microwave dissociation include: a microwave dissociation temperature of 40° C. to 110° C., and a microwave dissociation time of 0.1 min to 2 min.

[0012] Optionally, the process parameters of the microwave dissociation also include: a microwave dissociation power of 50W to 100W, and a microwave dissociation frequency of 2400MHz to 2500MHz.

[0013] Optionally, the liquid-to-solid ratio of the mixed system is (4-10):1.

[0014] Optionally, the particle size of the aluminum-containing electrolyte waste is 200 mesh to 300 mesh.

[0015] Optionally, under the condition of microwave dissociation, the aluminum-containing electrolyte waste, the catalyst and the acidic substance are mixed so that the aluminum-containing electrolyte waste and the acidic substance undergo a chemical reaction to obtain a first slurry; wherein the catalyst is a microwave dissociation additive having a surface activated catalytic effect, and then further comprising:

[0016] Performing solid-liquid separation on the first slurry to obtain a liquid substance;

[0017] The liquid substance is mixed with an aluminum precipitation additive to allow the liquid substance to undergo a precipitation reaction to obtain a second slurry containing aluminum fluoride.

[0018] Optionally, the aluminum precipitation additive includes at least one of the following: ammonium carbonate, sodium carbonate, sodium bicarbonate, sodium hydroxide, ammonia water; and / or,

[0019] The process parameters of the sedimentation reaction include: temperature of 30° C. to 95° C., time of 2 h to 10 h, and pH value of 2.5 to 6.0.

[0020] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0021] The method for extracting fluorine resources from aluminum-containing electrolyte waste provided in an embodiment of the present application, wherein the aluminum-containing electrolyte waste contains fluorine-containing minerals, and the method comprises: mixing the aluminum-containing electrolyte waste, a catalyst and an acidic substance under microwave dissociation conditions to allow the aluminum-containing electrolyte waste and the acidic substance to undergo a chemical reaction to obtain a first slurry; wherein the catalyst is a microwave dissociation additive having a surface-activated catalytic effect. Microwave dissociation can have a good selective dissociation effect on fluorine-containing minerals (cryolith and other fluorine-containing minerals) in aluminum-containing electrolyte waste, and can preferentially extract and dissociate fluorine-containing minerals from the minerals of aluminum-containing electrolyte waste, thereby generating internal stress on the binding surface of fluorine-containing minerals to form cracks and fissures, and can also destroy the internal molecular bonds of fluorine-containing minerals, causing the internal molecular bonds to loosen or break; the surface active catalytic effect of microwave dissociation additives can indirectly increase the steric hindrance of cryolite formation by changing the surface activity of these cracks, fissures, loose and broken surfaces or points, and promote cryolite to be more easily separated, thereby effectively playing a catalytic dissociation role; acidic substances can effectively corrode or coordinate with fluorine-containing minerals with cracks, gaps and broken molecular bonds, thereby generating water-soluble fluoride salts, so that the fluorine-containing minerals enter the liquid substance of the second slurry in the state of soluble fluoride salts, thereby improving the separation efficiency of fluorine resources in aluminum-containing electrolyte waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0024] Figure 1 A schematic flow chart of a method for extracting fluorine resources from aluminum-containing electrolyte waste provided in an embodiment of the present application;

[0025] Figure 2 An XRD diagram of aluminum fluoride obtained by a method for extracting fluorine resources from aluminum-containing electrolyte waste provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0027] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0028] In the present application, in the absence of any contrary description, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the present specification, the terms "including", "comprising", etc. refer to "including but not limited to". In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of the associated objects, indicating that there may be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A, B can be singular or plural. In this article, "at least one" refers to one or more, and "plural" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple. In the proportional relationship involved in this article, the parameters that need to be described by proportion should be understood as the first term of the proportional formula in the order of description, and the proportional numbers should be understood as the second term of the proportional formula. For example, the mass ratio of substance A, substance B, and substance C is 1:2:3, then substance A, substance B, and substance C should correspond one-to-one with the proportional numbers in the proportional formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0029] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0030] In a first aspect, an embodiment of the present application provides a method for extracting fluorine resources from aluminum-containing electrolyte waste, wherein the aluminum-containing electrolyte waste contains fluorine-containing minerals. Figure 1 A schematic diagram of a method for extracting fluorine resources from aluminum-containing electrolyte waste provided in an embodiment of the present application; see Figure 1 , the method comprising:

[0031] S1. Under microwave dissociation conditions, aluminum-containing electrolyte waste, a catalyst and an acidic substance are mixed to allow the aluminum-containing electrolyte waste and the acidic substance to undergo a chemical reaction to obtain a first slurry; wherein the catalyst is a microwave dissociation additive having a surface activated catalytic effect.

[0032] Aluminum-containing electrolyte waste is waste generated during the production of aluminum electrolysis. In aluminum electrolysis production, in order to reduce the melting point of alumina and increase the conductivity, an electrolyte system based on cryolite (Na3AlF6) is used. Fluorine-containing minerals are one of the important components of aluminum-containing electrolyte waste, mainly in the form of cryolite (Na3AlF6) and other fluorine-containing minerals. Therefore, improving the separation efficiency (dissociation rate) of fluorine resources in aluminum-containing electrolyte waste can be understood as fully separating cryolite (Na3AlF6) and other fluorine-containing minerals from aluminum-containing electrolyte waste, thereby achieving effective recovery of fluorine and aluminum in fluorine resources. The electrolyte-containing waste may include at least one of the following: carbon slag, electrolyte after carbon slag flotation, electrolyte after carbon slag pyrometallurgical treatment, electrolyte salvaged from the electrolytic cell, and regenerated electrolyte after treatment of fluorine-containing waste in the aluminum electrolytic cell.

[0033] Aluminum-containing electrolyte waste is a source of fluorine resources, and the waste contains fluorine-containing minerals in the form of cryolite. These fluorine-containing minerals are the extraction targets, and their structure and composition will change during the subsequent processing to achieve the separation of fluorine. When the fluorine-containing minerals produce cracks, fissures, and loose or broken bonds within the molecules after microwave dissociation, acidic substances can react with these structurally changed fluorine-containing minerals. Specifically, it can convert fluorine-containing minerals into water-soluble fluoride salts through corrosion or coordination reactions. For example, it may react with fluorine-containing minerals such as cryolite to allow fluorine to enter the solution in the form of ions, thereby achieving the transfer of fluorine from solid waste to liquid substances and improving the separation efficiency of fluorine resources. On the one hand, microwave dissociation additives with surface active catalytic effects cause fluorine-containing minerals to produce cracks, fissures, and changes in the internal molecular structure during the microwave dissociation process, and the additives indirectly increase the steric hindrance of cryolite formation by changing the surface activity of these changed parts (cracks, fissures, loose and fractured surfaces or points). In layman's terms, it makes it more difficult for cryolite to maintain its original structure in this environment, making it easier to separate. On the other hand, this change in surface activity promotes the entire dissociation process, plays a catalytic role, and accelerates the speed and degree of dissociation of fluorine-containing minerals from aluminum-containing electrolyte waste.

[0034] In some embodiments, the microwave dissociation additive includes at least one of the following: fluorotitanic acid, strontium chloride, strontium sulfate, and lanthanum carbonate.

[0035] In the embodiment of the present application, the microwave dissociation additive can be a combination of one or more of fluorotitanic acid (CAS No. 174439-11-1), strontium chloride (CAS No. 10476-85-4), strontium sulfate (CAS No. 7759-02-6), and lanthanum carbonate (CAS No. 6487-39-4). These microwave dissociation additives all have a surface activity change effect on the cross section of cryolite-type fluorine-containing minerals, indirectly increasing the steric hindrance of cryolite formation, thereby promoting the fluorine-containing minerals to be more easily separated by changing the surface activity of cracks, fissures, looseness and fracture surfaces or points of cryolite and other fluorine-containing minerals produced by microwave selective dissociation, and effectively playing a catalytic dissociation role.

[0036] In some embodiments, the acidic substance includes at least one of the following: an inorganic acid, an acidic aluminum salt.

[0037] In the embodiments of the present application, the acidic substance may be one or both of an inorganic acid and an acidic aluminum salt. Acidic substances can promptly invade cryolite and other fluorine-containing minerals with cracks, gaps, and broken molecular bonds, and corrode or coordinate with the unstable ends of the fluorine-containing minerals to generate water-soluble fluoride salts. Inorganic acids can react with cryolite and fluorine-containing minerals, and acidic aluminum salts can react with the fluorine contained in fluorine-containing minerals. Both the corrosion reaction and the coordination reaction can cause cryolite and fluorine-containing minerals to generate water-soluble fluoride salts. The inorganic acid may be a combination of one or more of sulfuric acid, hydrochloric acid, and nitric acid; the acidic aluminum salt may be one or both of aluminum sulfate and aluminum chloride.

[0038] In some embodiments, the weight of the microwave dissociation additive is 0.01‰ to 0.1‰ of the weight of the aluminum-containing electrolyte waste; and / or,

[0039] The weight of the acidic substance is 1.5 to 2.5 times the weight of the aluminum-containing electrolyte waste.

[0040] In the embodiment of the present application, the weight of the microwave dissociation additive can be 0.01‰ to 0.1‰ of the weight of the aluminum-containing electrolyte waste, which fully improves the separation efficiency of the fluorine-containing minerals of the aluminum-containing electrolyte waste, thereby promoting the subsequent generation of aluminum fluoride. If the weight of the microwave dissociation additive is higher than 0.1‰ of the weight of the aluminum-containing electrolyte waste, it may increase the impurities in the subsequent aluminum fluoride and reduce the purity; if the weight of the microwave dissociation additive is lower than 0.01‰ of the weight of the aluminum-containing electrolyte waste, it may cause the separation efficiency of the fluorine-containing minerals of the aluminum-containing electrolyte waste to be low, affecting the subsequent generation of aluminum fluoride. Exemplarily, the weight of the microwave dissociation additive can be 0.01‰, 0.02‰, 0.03‰, 0.04‰, 0.05‰, 0.06‰, 0.07‰, 0.08‰, 0.09‰, 0.01‰, etc. of the weight of the aluminum-containing electrolyte waste.

[0041] The weight of the acidic substance is 1.5 to 2.5 times the weight of the aluminum-containing electrolyte waste, and it can fully invade the fluorine-containing minerals with cracks, gaps and broken molecular bonds, and corrode or coordinate with the unstable ends of the fluorine-containing minerals to generate water-soluble fluoride salts. If the weight of the acidic substance is higher than 2.5 times the weight of the aluminum-containing electrolyte waste, it may cause the acidity and impurity ion content of the liquid substance in the second slurry obtained by microwave dissociation to be too high, resulting in excessive consumption of subsequent aluminum precipitation additives and excessive impurity content in the product; if the weight of the acidic substance is lower than 1.5 times the weight of the aluminum-containing electrolyte waste, it may cause insufficient separation efficiency of fluorine-containing minerals, resulting in excessively high content of meso-cryolite and fluorine in the solid substance in the second slurry obtained by microwave dissociation, affecting subsequent utilization. Illustratively, the weight of the acidic substance can be 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2.0 times, 2.1 times, 2.2 times, 2.3 times, 2.4 times, 2.5 times, etc., of the weight of the aluminum-containing electrolyte waste.

[0042] In some embodiments, the liquid-to-solid ratio of the mixed system is (4-10):1.

[0043] In the embodiment of the present application, the liquid substance of the mixed system is generally water, and the liquid-to-solid ratio of the mixed system can be (4-10):1, which can promote the rapid and timely dispersion of cracks, fissures, loose and fracture surfaces or points that are easier to separate, and further promote the selective dissociation of microwaves on fluorine-containing minerals deeper and deeper into the particles. Therefore, under the action of the above-mentioned microwave dissociation additives and acidic substances, the appropriate liquid-to-solid ratio of the first slurry can make the solid matter of the first slurry evenly dispersed, so that in the subsequent microwave dissociation, the fluorine-containing minerals are dissociated layer by layer and enter the aqueous solution in the state of soluble fluoride salts until all dissociation and reaction are completed, thereby improving the separation efficiency of fluorine resources in aluminum-containing electrolyte waste. Exemplarily, the liquid-to-solid ratio of the mixed system can be 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc.

[0044] In some embodiments, the aluminum-containing electrolyte waste has a particle size of 200 mesh to 300 mesh.

[0045] In the embodiment of the present application, the aluminum-containing electrolyte waste can be fine-particle aluminum-containing electrolyte waste, and the particle size of the aluminum-containing electrolyte waste can be 200 mesh to 300 mesh. "Mesh" is a unit for measuring particle size, which refers to the number of holes in the screen within an area of ​​1 inch × 1 inch (25.4mm × 25.4mm). For example, 200 mesh means that there are 200 holes on the screen of the above-mentioned specified area. The larger the mesh number, the smaller the holes in the screen, and the finer the particles that can pass through the screen. Therefore, the particle size of the aluminum-containing electrolyte waste is between 200 mesh and 300 mesh, indicating that the particle size of the waste is relatively uniform and relatively small as a whole. Smaller particle size means that the contact area between the waste and the acidic substance and the microwave dissociation additive is significantly increased, and the appropriate particle size is conducive to the selective dissociation of microwaves on fluorine minerals. Waste of this particle size has good dispersibility in the first slurry. For example, the particle size of the aluminum-containing electrolyte waste may be 200 mesh, 220 mesh, 240 mesh, 260 mesh, 280 mesh, 300 mesh, etc.

[0046] In some embodiments, the process parameters of the microwave dissociation include: a microwave dissociation temperature of 40° C. to 110° C., and a microwave dissociation time of 0.1 min to 2 min.

[0047] In an embodiment of the present application, the microwave dissociation can be achieved with a microwave reactor. The microwave dissociation temperature can be 40°C to 110°C, which fully realizes the separation of fluorine resources (fluorine-containing minerals) in aluminum-containing electrolyte waste. If the microwave dissociation temperature is higher than 110°C, a large amount of aluminum salts may be precipitated into the solid matter of the first slurry in advance, resulting in a decrease in the aluminum recovery rate and affecting the resource utilization of the solid matter of the first slurry. Exemplarily, the microwave dissociation temperature can be 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, etc. And the matching microwave dissociation time can be 0.1min to 2min. Exemplarily, the microwave dissociation time can be 0.1min, 0.2min, 0.3min, 0.4min, 0.5min, 0.7min, 0.9min, 1.2min, 1min, 1.4min, 1.6min, 1.8min, 2min, etc.

[0048] In some embodiments, the process parameters of the microwave dissociation include: a microwave dissociation power of 50W to 100W, and a microwave dissociation frequency of 2400MHz to 2500MHz.

[0049] In an embodiment of the present application, the microwave dissociation power can be 50W to 100W, providing sufficient dissociation energy for the fluorine-containing minerals of the aluminum-containing electrolyte waste. If the microwave dissociation power is greater than 100W, a large amount of aluminum salts will settle into the solid matter of the first slurry in advance, resulting in a decrease in the aluminum recovery rate and affecting the resource utilization of the solid matter of the first slurry. The microwave dissociation frequency can be 2400MHz to 2500MHz, which can fully realize the selective dissociation of fluorine-containing minerals of aluminum-containing electrolyte waste. Exemplarily, the microwave dissociation power can be 50W, 60W, 70W, 80W, 90W, 100W, etc.; the microwave dissociation frequency can be 2400MHz, 2420MHz, 2440MHz, 2460MHz, 2480MHz, 2490MHz, 2500MHz, etc.

[0050] In some embodiments, under the condition of microwave dissociation, the aluminum-containing electrolyte waste, the catalyst and the acidic substance are mixed so that the aluminum-containing electrolyte waste and the acidic substance undergo a chemical reaction to obtain a first slurry; wherein the catalyst is a microwave dissociation additive having a surface activated catalytic effect, and then further comprising:

[0051] S2, performing solid-liquid separation on the first slurry to obtain a liquid substance;

[0052] After microwave dissociation causes the fluorine-containing minerals in the aluminum-containing electrolyte waste to react with the acidic substances, the second slurry contains the soluble fluorine salts generated by the reaction (dissolved in the liquid substance) and unreacted solid substances, etc. Through solid-liquid separation, the liquid substance containing the target fluorine resources (in the form of fluorine salts) can be separated from the solid impurities, laying the foundation for the subsequent further extraction and purification of fluorine resources.

[0053] S3. Mixing the liquid substance with an aluminum precipitation additive to allow the liquid substance to undergo a sedimentation reaction to obtain a second slurry containing aluminum fluoride.

[0054] The obtained liquid substance contains the target fluoride salt. Under the action of the aluminum precipitation additive, the fluorine in the liquid substance combines with the aluminum to form aluminum fluoride. Figure 2 The XRD diagram of aluminum fluoride obtained by the method for extracting fluorine resources from aluminum-containing electrolyte waste provided in the embodiment of the present application is shown in FIG. Figure 2 It can be seen that the main phase of the aluminum fluoride product obtained is AlF3. Other metal cations in the liquid substance form soluble salts. Therefore, the full recovery of fluorine in aluminum-containing electrolyte waste is mainly to convert the fluorine resources in the waste into reusable aluminum fluoride, and other soluble salts can be further recovered and utilized, realizing the comprehensive utilization of multiple components in the waste.

[0055] In some embodiments, the aluminum precipitation additive includes at least one of the following: ammonium carbonate, sodium carbonate, sodium bicarbonate, sodium hydroxide, ammonia water; and / or,

[0056] The process parameters of the sedimentation reaction include: temperature of 30° C. to 95° C., time of 2 h to 10 h, and pH value of 2.5 to 6.0.

[0057] In the embodiment of the present application, the aluminum precipitation additive can be an alkaline substance, and the aluminum precipitation additive can be a combination of one or more of ammonium carbonate, sodium carbonate, sodium bicarbonate, sodium hydroxide, and ammonia. The process parameters of the precipitation reaction can include: a temperature of 30°C to 95°C, a time of 2h to 10h, and a pH value of 2.5 to 6.0 (depending on the weight of the aluminum precipitation additive), which can fully combine the fluorine and aluminum in the liquid substance to generate high-purity aluminum fluoride. Exemplarily, in the precipitation reaction, the temperature can be 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, etc.; the time can be 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, etc.; the pH value can be 2.5, 3, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, etc.

[0058] The third slurry containing aluminum fluoride is subjected to solid-liquid separation, and the obtained solid matter is dried to obtain an aluminum fluoride product. The main components of the aluminum fluoride product include aluminum fluoride and aluminum oxide, wherein the mass fraction of aluminum fluoride is greater than 95%, and there are no impurities harmful to the production of electrolytic aluminum, which fully meets the requirements of returning to the electrolytic cell, and can also be sold as a raw material for high-purity aluminum fluoride.

[0059] The method for extracting fluorine resources from aluminum-containing electrolyte waste provided in the embodiment of the present application has the following advantages:

[0060] (1) By taking advantage of the unique selective dissociation of microwaves, the surface active catalytic effect of microwave dissociation additives, the good timely dispersibility of the mixed system, and the synergistic effect of inorganic acid corrosion reaction or coordination reaction of acidic aluminum salts, microwave treatment can efficiently dissociate cryolite and other fluoride salts in aluminum electrolyte at lower temperature and shorter time;

[0061] (2) Under the action of aluminum precipitation additives, the liquid substance undergoes a precipitation reaction, which can combine fluorine and aluminum in the liquid substance to form aluminum fluoride, thereby ensuring the subsequent efficient conversion of aluminum fluoride. The purity of the product aluminum fluoride can reach more than 95%, realizing the effective recovery and conversion of fluorine resources.

[0062] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for the unrecorded specific conditions in the following examples are usually measured according to national standards. If there is no corresponding national standard, then carry out according to general international standards, normal conditions or according to the conditions recommended by the manufacturer.

[0063] Example 1

[0064] A method for extracting fluorine resources from aluminum-containing electrolyte waste, comprising:

[0065] Under microwave dissociation conditions, aluminum-containing electrolyte waste, catalyst and acidic substance are mixed to make the aluminum-containing electrolyte waste and the acidic substance react chemically to obtain a first slurry; wherein the catalyst is a microwave dissociation additive with surface activated catalytic effect; wherein the aluminum-containing electrolyte waste is obtained by crushing the carbon slag, passing it through a 200-mesh sieve, and taking the sieve under as the aluminum-containing electrolyte waste; the acidic substance is aluminum sulfate, and the weight of the aluminum sulfate is 2.0 times the weight of the aluminum-containing electrolyte waste; the microwave dissociation additive is fluorotitanic acid, and the weight of the fluorotitanic acid is 0.1‰ of the weight of the aluminum-containing electrolyte waste; the liquid-solid ratio of the mixed system is 5:1; the process parameters of microwave dissociation include: microwave dissociation temperature of 80°C, microwave dissociation time of 2min, microwave dissociation power of 100W, and microwave dissociation frequency of 2450MHz;

[0066] Performing solid-liquid separation on the first slurry to obtain a liquid substance;

[0067] The liquid substance and the aluminum precipitation additive are stirred and mixed to make the liquid substance undergo a precipitation reaction to obtain a second slurry containing aluminum fluoride; wherein the aluminum precipitation additive is ammonia water, and the process parameters of the precipitation reaction include: temperature of 95° C., time of 4 hours, and pH value of 5.5;

[0068] The second slurry containing aluminum fluoride is subjected to solid-liquid separation, and the obtained solid matter is washed and dried in sequence to obtain an aluminum fluoride product.

[0069] Example 2

[0070] A method for extracting fluorine resources from aluminum-containing electrolyte waste, comprising:

[0071] Under microwave dissociation conditions, aluminum-containing electrolyte waste, catalyst and acidic substance are mixed to make the aluminum-containing electrolyte waste and the acidic substance react chemically to obtain a first slurry; wherein the catalyst is a microwave dissociation additive with surface activated catalytic effect; wherein the aluminum-containing electrolyte waste is obtained by crushing the electrolyte after carbon slag pyrometallurgy treatment, passing it through a 200-mesh sieve, and taking the sieve under as the aluminum-containing electrolyte waste; the acidic substance is aluminum chloride, and the weight of aluminum chloride is 2.5 times the weight of the aluminum-containing electrolyte waste; the microwave dissociation additive is a mixture of strontium chloride and lanthanum carbonate (mass ratio 1:1), and the weight of the mixture of strontium chloride and lanthanum carbonate is 0.01‰ of the weight of the aluminum-containing electrolyte waste; the liquid-solid ratio of the mixed system is 4:1; the process parameters of microwave dissociation include: microwave dissociation temperature of 40°C, microwave dissociation time of 0.1min, microwave dissociation power of 50W, and microwave dissociation frequency of 2450MHz;

[0072] Performing solid-liquid separation on the first slurry to obtain a liquid substance;

[0073] The liquid substance and the aluminum precipitation additive are stirred and mixed to make the liquid substance undergo a precipitation reaction to obtain a second slurry containing aluminum fluoride; wherein the aluminum precipitation additive is ammonia water, and the process parameters of the precipitation reaction include: temperature of 80° C., time of 5 hours, and pH value of 2.5;

[0074] The second slurry containing aluminum fluoride is subjected to solid-liquid separation, and the obtained solid matter is washed and dried in sequence to obtain an aluminum fluoride product.

[0075] Example 3

[0076] A method for extracting fluorine resources from aluminum-containing electrolyte waste, comprising:

[0077] Under microwave dissociation conditions, aluminum-containing electrolyte waste, catalyst and acidic substance are mixed to make the aluminum-containing electrolyte waste and the acidic substance react chemically to obtain a first slurry; wherein the catalyst is a microwave dissociation additive with surface activated catalytic effect; wherein the aluminum-containing electrolyte waste is obtained by crushing the electrolyte salvaged from the aluminum electrolytic cell, passing it through a 200-mesh sieve, and taking the sieve-under material as the aluminum-containing electrolyte waste; the acidic substance is a mixture of sulfuric acid and aluminum sulfate (mass ratio 1:4), and the weight of the mixture of sulfuric acid and aluminum sulfate is 1.5 times the weight of the aluminum-containing electrolyte waste; the microwave dissociation additive is strontium sulfate, and the weight of strontium sulfate is 0.05‰ of the weight of the aluminum-containing electrolyte waste; the liquid-solid ratio of the mixed system is 5:1; the process parameter setting conditions of microwave dissociation include: microwave dissociation temperature is 110°C, microwave dissociation time is 1min, microwave dissociation power is 80W, and microwave dissociation frequency is 2450MHz;

[0078] Performing solid-liquid separation on the first slurry to obtain a liquid substance;

[0079] The liquid substance is stirred and mixed with an aluminum precipitation additive to allow the liquid substance to undergo a sedimentation reaction to obtain a second slurry containing aluminum fluoride; wherein the aluminum precipitation additive is ammonia water, and the process parameters of the sedimentation reaction include: temperature of 30°C, time of 10 hours, and pH value of 3.0.

[0080] The second slurry containing aluminum fluoride is subjected to solid-liquid separation, and the obtained solid matter is washed and dried in sequence to obtain an aluminum fluoride product.

[0081] Example 4

[0082] A method for extracting fluorine resources from aluminum-containing electrolyte waste, comprising:

[0083] Under microwave dissociation conditions, aluminum-containing electrolyte waste, catalyst and acidic substance are mixed to make the aluminum-containing electrolyte waste and the acidic substance react chemically to obtain a first slurry; wherein the catalyst is a microwave dissociation additive with surface activated catalytic effect; wherein the aluminum-containing electrolyte waste is obtained by crushing the electrolyte after carbon slag flotation, passing through a 200-mesh sieve, and taking the sieve under as the aluminum-containing electrolyte waste; the acidic substance is a mixture of sulfuric acid and aluminum sulfate (mass ratio 1:2), and the weight of the mixture of sulfuric acid and aluminum sulfate is 1.9 times the weight of the aluminum-containing electrolyte waste; the microwave dissociation additive is lanthanum carbonate, and the weight of lanthanum carbonate is 0.03‰ of the weight of the aluminum-containing electrolyte waste; the liquid-solid ratio of the mixed system is 6:1; the process parameter setting conditions of microwave dissociation include: microwave dissociation temperature is 70°C, microwave dissociation time is 0.3min, microwave dissociation power is 60W, and microwave dissociation frequency is 2450MHz;

[0084] Performing solid-liquid separation on the first slurry to obtain a liquid substance;

[0085] The liquid substance and the aluminum precipitation additive are stirred and mixed to make the liquid substance undergo a precipitation reaction to obtain a second slurry containing aluminum fluoride; wherein the aluminum precipitation additive is ammonia water, and the process parameters of the precipitation reaction include: temperature of 70° C., time of 6 hours, and pH value of 4.5;

[0086] The second slurry containing aluminum fluoride is subjected to solid-liquid separation, and the obtained solid matter is washed and dried in sequence to obtain an aluminum fluoride product.

[0087] Example 5

[0088] A method for extracting fluorine resources from aluminum-containing electrolyte waste, comprising:

[0089] Under microwave dissociation conditions, aluminum-containing electrolyte waste, catalyst and acidic substance are mixed to make the aluminum-containing electrolyte waste and the acidic substance react chemically to obtain a first slurry; wherein the catalyst is a microwave dissociation additive with surface activated catalytic effect; wherein the aluminum-containing electrolyte waste is obtained by crushing the electrolyte after carbon slag flotation, passing through a 200-mesh sieve, and taking the sieve under as the aluminum-containing electrolyte waste; the acidic substance is a mixture of hydrochloric acid and aluminum chloride (mass ratio 2:3), and the weight of aluminum sulfate is 2.2 times the weight of the aluminum-containing electrolyte waste; the microwave dissociation additive is a mixture of fluorotitanic acid and strontium chloride (mass ratio 1:3), and the weight of the mixture of fluorotitanic acid and strontium chloride is 0.08‰ of the weight of the aluminum-containing electrolyte waste; the liquid-solid ratio of the mixed system is 7:1; the process parameters of microwave dissociation include: microwave dissociation temperature of 90°C, microwave dissociation time of 1.5min, microwave dissociation power of 85W, and microwave dissociation frequency of 2450MHz;

[0090] Performing solid-liquid separation on the first slurry to obtain a liquid substance;

[0091] The liquid substance is stirred and mixed with an aluminum precipitation additive to allow the liquid substance to undergo a sedimentation reaction to obtain a second slurry containing aluminum fluoride; wherein the aluminum precipitation additive is ammonia water, and the process parameters of the sedimentation reaction include: temperature of 35°C, time of 7h, and pH value of 6.0.

[0092] The second slurry containing aluminum fluoride is subjected to solid-liquid separation, and the obtained solid matter is washed and dried in sequence to obtain an aluminum fluoride product.

[0093] Comparative Example 1

[0094] In Comparative Example 1, the weight of the microwave dissociation additive is 0.005‰ of the weight of the aluminum-containing electrolyte waste, and the other steps are the same as those in Example 1;

[0095] Comparative Example 2

[0096] In Comparative Example 2, the weight of the microwave dissociation additive is 0.15‰ of the weight of the aluminum-containing electrolyte waste, and the other steps are the same as those in Example 1;

[0097] Comparative Example 3

[0098] In Comparative Example 3, the microwave dissociation temperature was 150° C., and the other steps were the same as in Example 1.

[0099] Comparative Example 4

[0100] In Comparative Example 4, the microwave dissociation temperature was 25° C., and the other steps were the same as in Example 1.

[0101] Comparative Example 5

[0102] In Comparative Example 5, the microwave dissociation power is 40 W, and the other steps are the same as in Example 1.

[0103] Comparative Example 6

[0104] In Comparative Example 6, the microwave dissociation power is 150 W, and the other steps are the same as in Example 1.

[0105] Comparative Example 7

[0106] In Comparative Example 7, the microwave dissociation time was 0.05 min, and the other steps were the same as in Example 1.

[0107] Comparative Example 8

[0108] In Comparative Example 8, the microwave dissociation time was 5 min, and the other steps were the same as in Example 1.

[0109] Comparative Example 9

[0110] The pH value of the sedimentation reaction in Comparative Example 9 was 2.0, and the other steps were the same as in Example 1.

[0111] Comparative Example 10

[0112] The pH value of the sedimentation reaction in Comparative Example 10 was 7.0, and the other steps were the same as in Example 1.

[0113] The reaction conditions in Examples 1 to 5 and Comparative Examples 1 to 10 and the purity of the final products are shown in Table 1.

[0114] Table 1 Reaction conditions and purity statistics of final products in Examples 1 to 5 and Comparative Examples 1 to 10

[0115]

[0116] From the data in Table 1, it can be seen that in Examples 1 to 5, the purity of the product is higher than 95.0%. It reflects (1) the use of microwaves and additives to achieve low-temperature, short-time, high-efficiency microwave dissociation and rapid dispersion of fluorine-containing minerals in aqueous solution, ensuring the subsequent generation rate of aluminum fluoride. (2) The product has high added value: under the use of aluminum precipitation additives, fluorine and aluminum in the solution efficiently form aluminum fluoride. After washing and drying, the aluminum fluoride product has high purity and the aluminum fluoride content is greater than 95%. It can be used as a raw material for electrolytic cells, and can also be sold as a raw material for high-purity aluminum fluoride, realizing the recycling of fluorine resources.

[0117] Analysis of Comparative Examples 1 to 10: In Comparative Example 1, the weight of the microwave dissociation additive is 0.005‰ of the weight of the fine-grained aluminum-containing electrolyte waste. Since too little microwave dissociation additive is added in Comparative Example 1, the degree of microwave dissociation is insufficient, resulting in the aluminum content in the leaching residue (solid matter of the first slurry) being 0.05%, which reduces the aluminum recovery rate (cryolith is not effectively dissociated) and affects the resource utilization of the leaching residue.

[0118] The weight of the microwave dissociation additive in Comparative Example 2 is 0.15‰ of the weight of the fine-particle aluminum-containing electrolyte waste. Since the microwave dissociation additive is added too much in Comparative Example 2, the impurity content of the product is increased and the product purity is lower than 95.0%.

[0119] In Comparative Example 3, the microwave dissociation temperature is 150° C., which exceeds the range of 40 to 110° C. in the embodiment of the present application. A large amount of aluminum salt will settle into the leaching residue in advance, resulting in an aluminum content of 0.06% in the leaching residue, resulting in a decrease in the aluminum recovery rate and also affecting the resource utilization of the leaching residue.

[0120] In Comparative Example 4, the microwave dissociation temperature is 25° C., which exceeds the range of 40 to 110° C. in the embodiment of the present application. The dissociation reaction power is insufficient, resulting in a low dissociation rate. The aluminum content in the leached slag is 5.0%, resulting in a decrease in the aluminum recovery rate and also affecting the resource utilization of the leached slag.

[0121] The microwave dissociation power described in Comparative Example 5 is 40 W, which exceeds the range of 50 to 100 W in the embodiment of the present application. The dissociation reaction power is insufficient, resulting in a low dissociation rate. The aluminum content in the leached slag is 4.8%, resulting in a decrease in the aluminum recovery rate and also affecting the resource utilization of the leached slag.

[0122] The microwave dissociation power described in Comparative Example 6 is 150 W, which exceeds the range of 50 to 100 W in the embodiment of the present application. The dissociation temperature is too high, and a large amount of aluminum salt will settle into the leaching residue in advance, resulting in an aluminum content of 0.10% in the leaching residue, resulting in a decrease in the aluminum recovery rate and affecting the resource utilization of the leaching residue.

[0123] In Comparative Example 7, the microwave dissociation time is 0.05 min, which is too short, resulting in a low dissociation rate of cryolite and other fluorine-containing minerals. The aluminum content in the leached residue is 3.24%, resulting in a decrease in the aluminum recovery rate and also affecting the resource utilization of the leached residue.

[0124] In Comparative Example 8, the microwave dissociation time was 5 min, which was too long and had high energy consumption.

[0125] In Comparative Example 9, the pH value of the precipitation reaction was 2.0, and the pH value of aluminum precipitation was too low, which affected the formation rate of aluminum fluoride, resulting in the aluminum fluoride content in the product being only 93.1%.

[0126] The pH value of the sedimentation reaction in Comparative Example 10 was 7.0. The pH value of the sedimentation reaction was too high, causing other ions to precipitate out together, seriously affecting the purity of the product aluminum fluoride, resulting in the aluminum fluoride content in the product being only 89.2%.

[0127] One or more technical solutions in the embodiments of the present application also have at least the following technical effects or advantages:

[0128] (1) By utilizing the unique selective dissociation advantages of microwaves, at a relatively low temperature and in a relatively short time, under the catalytic effect of the surface activity of microwave dissociation additives, cryolite and other fluorine-containing minerals can generate internal stress on the mineral bonding surface to form cracks and fissures, and can also destroy the internal molecular bonds. At the same time, in an aqueous solution system, cryolite and other fluorine-containing minerals with cracks, fissures or destroyed internal molecular bonds are more easily decomposed and diffused than pure solid phases, thus achieving efficient dissociation of cryolite and other fluoride salts in aluminum electrolytes and ensuring efficient subsequent conversion of aluminum fluoride;

[0129] (2) Under the action of the aluminum precipitation additive, the fluorine and aluminum in the liquid substance are highly combined to form aluminum fluoride, and other metal cations form soluble salts. After washing and drying, the product aluminum fluoride has high purity and an aluminum fluoride content of more than 95%. It can be used as a raw material for electrolytic cells and can also be sold as a raw material for high-purity aluminum fluoride, thus realizing the recycling of fluorine resources;

[0130] (3) The embodiments of the present application can realize the high-value and resource utilization of aluminum-containing electrolyte waste under the premise of low energy consumption;

[0131] (4) The method for extracting fluorine resources from aluminum-containing electrolyte waste provided in the embodiment of the present application overcomes the shortcomings of the prior art such as long-term high-temperature microwave roasting or long-term microwave dissociation leaching under certain pressure conditions, high energy consumption, severe corrosion to equipment, and low fluoride dissociation rate.

[0132] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for extracting fluorine resources from aluminum-containing electrolyte waste, wherein the aluminum-containing electrolyte waste contains fluorine-containing minerals, the method comprising: Under microwave dissociation conditions, aluminum-containing electrolyte waste, a catalyst and an acidic substance are mixed to allow the aluminum-containing electrolyte waste and the acidic substance to undergo a chemical reaction to obtain a first slurry; wherein the catalyst is a microwave dissociation additive having a surface activated catalytic effect.

2. The method according to claim 1, characterized in that The microwave dissociation additive includes at least one of the following: fluorotitanic acid, strontium chloride, strontium sulfate, and lanthanum carbonate.

3. The method according to claim 1, characterized in that The acidic substance includes at least one of the following: an inorganic acid and an acidic aluminum salt.

4. The method according to any one of claims 1 to 3, characterized in that: The weight of the microwave dissociation additive is 0.01‰ to 0.1‰ of the weight of the aluminum-containing electrolyte waste; and / or, The weight of the acidic substance is 1.5 to 2.5 times the weight of the aluminum-containing electrolyte waste.

5. The method according to claim 1, characterized in that The process parameters of the microwave dissociation include: a microwave dissociation temperature of 40° C. to 110° C. and a microwave dissociation time of 0.1 min to 2 min.

6. The method according to claim 1 or 5, characterized in that: The process parameters of the microwave dissociation include: microwave dissociation power of 50W to 100W, and microwave dissociation frequency of 2400MHz to 2500MHz.

7. The method according to claim 1, characterized in that The liquid-to-solid ratio of the mixed system is (4-10):

1.

8. The method according to claim 1, characterized in that The particle size of the aluminum-containing electrolyte waste is 200-300 meshes.

9. The method according to claim 1, characterized in that: The aluminum-containing electrolyte waste, the catalyst and the acidic substance are mixed under the condition of microwave dissociation, so that the aluminum-containing electrolyte waste and the acidic substance undergo a chemical reaction to obtain a first slurry, and then the method further includes: Performing solid-liquid separation on the first slurry to obtain a liquid substance; The liquid substance is mixed with an aluminum precipitation additive to allow the liquid substance to undergo a precipitation reaction to obtain a second slurry containing aluminum fluoride.

10. The method according to claim 9, characterized in that The aluminum precipitation additive includes at least one of the following: ammonium carbonate, sodium carbonate, sodium bicarbonate, sodium hydroxide, ammonia water; and / or, The process parameters of the sedimentation reaction include: temperature of 30° C. to 95° C., time of 2 h to 10 h, and pH value of 2.5 to 6.0.

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