Method for enhancing extraction of valuable components in solid waste by using composite chlorinating agent

Abstract

The invention provides a method for strengthening extraction of valuable components in solid waste through a composite chlorinating agent, and relates to the technical field of recycling of lithium-containing waste. According to the method for strengthening extraction of the valuable components in the solid waste through the composite chlorinating agent, the lithium-containing solid waste and the composite chlorinating agent are mixed, pelletized and dried, and green pellets are obtained; after roasting, obtaining a cooked pellet; carrying out low-acid leaching and solid-liquid separation on the cooked pellets to obtain a lithium-containing leaching solution and leaching residues, and carrying out circulating leaching and solid-liquid separation on the leaching residues by using the lithium-containing leaching solution to obtain a high-lithium leaching solution; adding sodium carbonate into the high-lithium leaching solution to carry out lithium precipitation reaction, and carrying out solid-liquid separation to obtain crude lithium carbonate; and purifying and crystallizing the crude lithium carbonate to obtain the battery-grade lithium carbonate. According to the method, the composite chlorinating agent and the lithium-containing solid waste are adopted for pelletizing and roasting, a good mass transfer effect can be achieved at a lower temperature, the reaction efficiency in the roasting process is improved, energy consumption is reduced, and clean and efficient recovery of lithium is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of recycling and utilizing lithium-containing waste, and in particular to a method for enhancing the extraction of valuable components from solid waste using a composite chlorinating agent. Background Art

[0002] Lithium is the lightest and lightest metal in nature. Compared with other metals, lithium has a higher energy density. These characteristics make lithium a key ingredient in new energy batteries. Therefore, lithium is also known as the "white oil" of the Fourth Industrial Revolution and has become an indispensable strategic metal.

[0003] Solid waste containing lithium fluoride primarily includes: some lithium-containing waste cathodes and lithium-rich aluminum electrolytes (primarily composed of carbon, aluminum, fluorine, sodium, and lithium, with a Li content typically between 0.5% and 2.5%) from the electrolytic aluminum industry; lithium-containing precipitate residues or other lithium-containing waste residues (with a Li content between 0 and 2%) from the lithium battery recycling industry; and lithium-containing waste glass (with a Li content between 5 and 7%) from the fluorinated glass production industry. Due to the lack of a mature and economical recycling process, lithium fluoride-containing solid waste is mostly stockpiled. However, improper handling of lithium fluoride-containing solid waste can have negative environmental impacts and, given the current rapidly increasing demand for lithium, represents a waste of resources.

[0004] The main recovery processes currently under research include acid leaching and roasting-leaching. The acid leaching method primarily uses high-acid leaching to extract lithium fluoride. For example, patent CN114438329B employs a 0.1-10 mol / L acid solution with the addition of a leaching enhancer to leach the lithium-aluminum electrolyte. The leachate is then subjected to alkaline precipitation and other methods to produce a purified lithium solution. This process offers the advantage of yielding a variety of chemical products, but it also has significant disadvantages. High-acid leaching results in the leaching of large amounts of impurities (especially F and Al), increasing the difficulty of lithium solution purification and the consumption of sodium alkali. Furthermore, Al and F are highly concentrated in the leachate, entraining a significant amount of lithium during the precipitation of the hydrated fluoroaluminum complex, resulting in a low final lithium yield. The roasting-leaching method primarily involves mixing lithium-containing waste with sulfate or calcium salt auxiliary materials and roasting them at high temperature to convert the lithium into sulfate, followed by water leaching for lithium extraction. The process is simple, but there are the following problems: (1) The simple mixing of raw materials and auxiliary materials is not conducive to the smooth progress of the mass transfer process during industrial amplification, and the reaction stability is difficult to ensure. The reaction process requires an excess of calcium salt or sulfate additives; (2) The raw materials and auxiliary materials contain water, and when roasted under high temperature conditions, highly corrosive hydrogen fluoride gas will be generated; (3) The optimal roasting temperature is mostly above 800°C, and the energy consumption required is high; (4) At the same time as the lithium is converted into sulfate, other impurities in the waste residue will also be converted into sulfate. For example, when aluminum salt is soaked in dilute acid or water, a considerable amount of aluminum will still enter the lithium leaching solution, and further lithium-aluminum separation will cause lithium loss.

[0005] In view of the problems exposed in the above technical solutions, such as difficulty in impurity separation, high roasting temperature, low conversion efficiency, hydrogen fluoride corrosion, and industrial scale-up, it is urgent to develop a relatively clean and efficient lithium extraction technology for lithium-containing solid waste. Summary of the Invention

[0006] The purpose of the present application is to provide a method for enhancing the extraction of valuable components in solid waste by using a composite chlorinating agent. By pelletizing and drying the lithium-containing solid waste and the composite chlorinating agent, the reaction during the roasting process is made more complete and uniform, thereby preventing the generation of hydrofluoric acid gas. The metal elements in the chlorinating agent have a strong affinity for fluorine, and most fluorides are poorly soluble in water, which is conducive to the deep separation of lithium and fluorine. In addition, the use of the composite chlorinating agent can achieve a good mass transfer effect at a lower temperature, reduce the energy consumption required for roasting, and achieve clean and efficient recovery of lithium.

[0007] To achieve the above objectives, the technical solutions of this application are as follows: The present application provides a method for enhancing the extraction of valuable components from solid waste using a composite chlorinating agent, comprising: mixing lithium-containing solid waste with a composite chlorinating agent, pelletizing, and drying to obtain green pellets; roasting the raw pellets to obtain cooked pellets; The cooked pellets are subjected to low-acid leaching and solid-liquid separation to obtain a lithium-containing leachate and a leach residue, and the leach residue is cyclically leached with the lithium-containing leachate and subjected to solid-liquid separation to obtain a high-lithium leachate; adding sodium carbonate to the high-lithium leachate to carry out lithium precipitation reaction, and performing solid-liquid separation to obtain crude lithium carbonate; The crude lithium carbonate is purified and crystallized to obtain battery-grade lithium carbonate. Preferably, the lithium-containing solid waste includes at least one of: lithium-containing battery waste residue, lithium-aluminum-containing electrolyte, lithium-containing waste cathode, and lithium-containing waste glass; and / or, the lithium-containing solid waste comprises solid waste in the form of LiF; And / or, the mass proportion of Li in the lithium-containing solid waste is 0.01%-7%; And / or, the composite chlorinating agent includes at least two of calcium chloride, magnesium chloride, ferric chloride, ferrous chloride, ammonium chloride, cupric chloride, cuprous chloride, zinc chloride, lead chloride, aluminum chloride, and carbon tetrachloride; And / or, the composite chlorinating agent includes a binary system composite chlorinating agent or a multi-component system composite chlorinating agent.

[0008] Further preferably, the binary system composite chlorinating agent comprises: magnesium chloride and calcium chloride in a molar ratio of 1:1, sodium chloride and calcium chloride in a molar ratio of 1:1, potassium chloride and calcium chloride in a molar ratio of 1:4, or potassium chloride and magnesium chloride in a molar ratio of 2:3; And / or, the composite chlorinating agent of the multi-component system includes: potassium chloride, calcium chloride and magnesium chloride in a molar ratio of 6.5:0.3:3.2, or potassium chloride, calcium chloride and magnesium chloride in a molar ratio of 2:3.5:4.5.

[0009] Preferably, before the lithium-containing solid waste is mixed with the composite chlorinating agent, the process further comprises: finely grinding the lithium-containing solid waste to obtain a finely ground raw material, wherein the residue of the finely ground raw material passing through a 100-mesh sieve is less than 50%.

[0010] Preferably, the mixing with the composite chlorinating agent and pelletizing comprises: Mixing the composite chlorinating agent with the lithium-containing solid waste raw material, and then adding water to perform the pelletizing; Alternatively, the composite chlorinating agent is dissolved in water, and then the lithium-containing solid waste raw material is added to perform the mixing and pelletizing; The mass of the water is 10%-25% of the mass of the lithium-containing solid waste raw material.

[0011] Preferably, the size of the green pellets is 5mm-15mm; And / or, the drying comprises: drying the green pellets after pelletization at 80° C.-200° C. for 0.5 h-7 h to obtain dry green pellets with a water content of ≤0.5 wt %; And / or, the calcination temperature is 400°C-700°C, and the calcination time is 1h-3h; And / or, before the cooked pellets are subjected to low-acid leaching, the method further comprises: crushing and fine-grinding the cooked pellets to obtain pellet powder, wherein the pellet powder has a sieve residue of less than 50% when passing through a 100-mesh sieve.

[0012] Preferably, the acid used for the low-acid leaching includes at least one of sulfuric acid and hydrochloric acid; and / or, the liquid-to-solid ratio of the low-acid leaching is (3-6):1; And / or, the leaching time of the low-acid leaching is 2h-4h, and the leaching temperature is 20°C-60°C; and / or, the pH value of the lithium-containing leachate is 3-6; And / or, the number of cycles of the cyclic leaching is 2 to 8 times; And / or, the lithium concentration in the high-lithium leaching solution is greater than 15 g / L.

[0013] Preferably, before the high-lithium leachate is subjected to lithium precipitation reaction, the process further comprises: adjusting the pH value of the high-lithium leachate to 6-8, performing a first-stage precipitation and impurity removal to obtain a first-stage purified lithium solution; subjecting the impurity-removed solution to resin defluorination treatment to obtain a defluorinated lithium solution; adjusting the pH value of the defluorinated lithium solution to 10-11, performing a second-stage precipitation and impurity removal to obtain a purified lithium solution; And / or, before the sodium carbonate is subjected to lithium precipitation reaction, the method further comprises: preparing the sodium carbonate into a saturated sodium carbonate solution, and performing resin purification treatment to obtain a purified sodium carbonate solution; And / or, the temperature for the lithium precipitation reaction is 80° C.-95° C.; And / or, the crude lithium carbonate is purified and crystallized, including: preparing the crude lithium carbonate into a slurry, introducing CO2 into the slurry, separating the solid and liquid, and obtaining a filtrate; deeply removing impurities from the filtrate to obtain a lithium bicarbonate solution; heating the lithium bicarbonate solution for crystallization to precipitate lithium carbonate.

[0014] Further preferably, the mass ratio of water in the slurry to the crude lithium carbonate is (10-25):1; and / or, when the CO2 is introduced, the temperature of the slurry is 20°C-40°C; And / or, the deep impurity removal comprises: treating the filtrate with a macroporous chelating ion exchange resin, so that the concentration of impurity ions in the obtained lithium bicarbonate solution is less than 5 mg / L; And / or, the temperature of the heating crystallization is 80°C-90°C; And / or, after the lithium carbonate is precipitated, the method further includes: adding water to the lithium carbonate to prepare a slurry for washing, and then drying the washed lithium carbonate to obtain the battery-grade lithium carbonate.

[0015] Preferably, the molar ratio of the Li element in the lithium-containing solid waste to the Cl element in the composite chlorinating agent is 1:(1-10).

[0016] Beneficial effects of this application: (1) This application uses a composite chlorinating agent and lithium-containing solid waste for roasting, which can achieve good mass transfer effects at lower temperatures and obtain higher lithium recovery rates. On the one hand, because the melting points of single chlorinating agents, such as sodium chloride and potassium chloride, are mostly higher than 700°C, after different chlorinating agents are compounded, a eutectic with a lower eutectic temperature can be formed. Then, in the roasting reaction system, a micro-liquid phase can be formed at low temperature, and the solid-solid reaction with limited mass transfer rate is converted into a liquid-solid reaction, which greatly enhances the reaction efficiency. On the other hand, the presence of the molten salt system not only promotes the mass transfer process of the reactants, but also significantly improves the activation efficiency of the lithium element through the ion migration mechanism. In the low eutectic system formed by the composite chlorinating agent, the permeability of the molten salt to the lithium-containing mineral is enhanced, which can destroy the chemical bonding between lithium and the aluminosilicate lattice, and release lithium in the form of soluble lithium chloride.

[0017] (2) The purpose of making the composite chlorinating agent and lithium-containing solid waste into pellets in this application is not only to prevent ringing during the roasting process and facilitate material discharge, but more importantly, the pellets serve as orderly and regular small reactors. Especially when roasting in a rotary kiln, there will be no "stratification" between the raw materials and additives during the movement of the roasting materials due to differences in physical properties such as density, and the target reaction in each pellet microreactor will proceed more fully and evenly.

[0018] (3) In the process of the present application, the separation of lithium and impurity elements has obvious advantages. The process does not produce highly corrosive fluorine-containing gases. The fluorine element is basically fixed in the solid slag. Moreover, the aluminum in the lithium-containing solid waste will not be chlorinated during the whole process because the reaction Gibbs free energy is positive within the temperature range (such as the reaction of aluminum fluoride and calcium chloride): AlF3+ 1.5CaCl2= 1.5CaF2+ AlCl3△G>0 (when T<800℃); The present application achieves efficient recovery of lithium, a simple impurity removal process, low reagent consumption, and the prepared battery-grade lithium carbonate has high added value, stable product quality, and strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0020] Figure 1 This is a schematic flow chart of the method for enhancing the extraction of valuable components from solid waste using a composite chlorinating agent provided in this application. DETAILED DESCRIPTION

[0021] As used herein: "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus. The conjunction "consisting of" excludes any unspecified element, step, or component.

[0022] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed alone. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0023] In these examples, parts and percentages are by mass unless otherwise indicated.

[0024] "Parts by mass" refers to the basic unit of measurement used to express the mass ratio of multiple components. One part can represent any unit of mass, such as 1g or 2.689g. For example, if we say that the parts by mass of component A are a parts and the parts by mass of component B are b parts, this means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, we could say that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number representing a multiplication factor). It's important to note that, unlike parts by mass, the sum of the parts by mass of all components is not limited to 100 parts.

[0025] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0026] The lithium-containing solid waste raw materials used in the technical solution of this application include: lithium-containing waste slag from the battery recycling industry, lithium-containing aluminum electrolytes and lithium-containing waste cathodes from the aluminum electrolysis industry, and lithium-containing waste from the glass production industry. The method provided in this application is a recycling process that can produce battery-grade lithium carbonate and can process lithium-containing solid waste in the form of LiF or Li2O, where the lithium content ranges from 0.01wt% to 7wt%.

[0027] The present application provides a method for extracting valuable components from solid waste by using a composite chlorinating agent. The specific steps are as follows: Figure 1 Shown, including: (1) The lithium-containing solid waste is finely ground to obtain a finely ground raw material, and the sieve residue of the finely ground raw material passing through a 100-mesh sieve is less than 50%, that is, more than half of the finely ground raw material can pass through the 100-mesh sieve.

[0028] (2) preparing a composite chlorinating agent, preferably using at least two chlorinating agents selected from calcium chloride, magnesium chloride, ferric chloride, ferrous chloride, ammonium chloride, cupric chloride, cuprous chloride, zinc chloride, lead chloride, aluminum chloride, and carbon tetrachloride to form a low eutectic mixture.

[0029] Further preferably, the binary system formed by combining two chlorinating agents includes: magnesium chloride and calcium chloride in a molar ratio of 1:1, sodium chloride and calcium chloride in a molar ratio of 1:1, potassium chloride and calcium chloride in a molar ratio of 1:4, or potassium chloride and magnesium chloride in a molar ratio of 2:3. The ternary system formed by combining three chlorinating agents includes: potassium chloride, calcium chloride and magnesium chloride in a molar ratio of 6.5:0.3:3.2, or potassium chloride, calcium chloride and magnesium chloride in a molar ratio of 2:3.5:4.5. In addition, the composite chlorinating agent of the present application can also use four, five or more chlorinating agents to form a more complex system.

[0030] It should be noted that the melting points of pure sodium chloride, pure potassium chloride, pure magnesium chloride, and pure calcium chloride are 801°C, 770°C, 714°C, and 772°C, respectively. However, when sodium chloride and calcium chloride are mixed in a molar ratio of 1:1, a eutectic with a eutectic temperature of approximately 498°C is obtained; when potassium chloride and magnesium chloride are mixed in a molar ratio of 2:3, a eutectic with a eutectic temperature of approximately 474°C is obtained; and when potassium chloride, calcium chloride, and magnesium chloride are mixed in a molar ratio of 6.5:0.3:3.2, a eutectic with a eutectic temperature of 423°C is formed. This means that the present application can convert a solid-solid reaction with a limited mass transfer rate into a liquid-solid reaction below 500°C, thereby improving the reaction efficiency, that is, achieving a good mass transfer effect at a lower roasting temperature.

[0031] (3) The finely ground raw materials are mixed with the composite chlorinating agent and pelletized. Specifically, the finely ground raw materials and the composite chlorinating agent are first fully mixed, and then water is added to form pellets. Alternatively, the composite chlorinating agent is first dissolved in water, and then added to the finely ground raw materials for mixing and pelletization. The second mixing method is preferred.

[0032] In one embodiment of the present application, a disc granulator is used for pelletizing, and the size of the green pellets obtained by pelletizing needs to be controlled to be 5 mm to 15 mm.

[0033] In one embodiment of the present application, the mass of water required for pelletizing is 10%-25% of the mass of the finely ground raw material.

[0034] In one embodiment of the present application, the molar ratio of the Cl element in the composite chlorinating agent to the Li element in the lithium-containing solid waste raw material is (1-10):1.

[0035] (4) Drying the green pellets obtained by pelletization, specifically drying them at a temperature of 80°C-200°C for 0.5h-7h, so that the water content of the green pellets is ≤0.5wt%. This is mainly to prevent the generation of hydrogen fluoride gas during subsequent high-temperature roasting.

[0036] (5) The dried green pellets are roasted at a temperature of 400°C to 700°C for 1 hour to 3 hours. The roasting equipment can be a muffle furnace or a rotary kiln. The Gibbs free energy change and equilibrium constant of the lithium extraction reaction during the roasting process at different temperatures are shown in Tables 1 and 2. The cooked pellets obtained after cooling are crushed and finely ground so that more than 50% of the ground material can pass through a 100-mesh sieve.

[0037] Table 1 Gibbs free energy change and equilibrium constant of lithium extraction reaction during calcination at 500℃

[0038] Table 2 Lithium extraction reaction and its Gibbs free energy change and equilibrium constant during calcination at 700℃

[0039] (6) The finely ground pellet powder is acid-leached. The acid-leaching conditions include: liquid-solid ratio (3-6): 1, leaching time 2h-4h, leaching temperature 20℃-60℃, and controlling the pH value of the leaching process to 3-6, preferably 3.5-4. At this time, the impurity leaching rate is low and the lithium leaching rate is high, greater than 90%. In this pH range, Al 3+ 、Fe 3+ The precipitation pH range can not only ensure a high lithium leaching rate, but also control the impurity content in the leachate.

[0040] In one embodiment of the present application, the reagent used for acid leaching includes at least one of sulfuric acid and hydrochloric acid.

[0041] (7) The leachate after acid leaching is used for cyclic leaching. Because the lithium concentration in the leachate after one acid leaching is generally around 2g / L-5g / L, it basically cannot meet the concentration required for the preparation of lithium carbonate (>15g / L). At the same time, the acidity in the leachate is relatively high. In order to neutralize its acidity, the lithium-containing leachate after acid leaching is selected to continue to circulate the leach residue for 2-8 cycles until the lithium concentration in the leachate is >15g / L. The cyclic leaching is stopped and filtered to obtain a high-lithium leachate.

[0042] (8) The obtained high-lithium leaching solution is purified by first adjusting the pH value of the system to 5-7 and performing a first-stage precipitation removal, which mainly removes aluminum and iron elements in the solution. Then, resin is used for deep fluorine removal. Then, the pH value of the system is adjusted to 10-11 and a second-stage precipitation removal is performed, which mainly removes calcium and magnesium elements to obtain a purified lithium solution.

[0043] (9) The purified lithium solution is subjected to lithium precipitation reaction to obtain crude lithium carbonate.

[0044] Specifically, industrial-grade sodium carbonate is prepared into a saturated sodium carbonate solution, which is then filtered to remove insoluble matter and treated with resin to fully remove impurity ions to obtain a qualified sodium carbonate solution. The sodium carbonate solution and the purified high-lithium leachate are then heated to 80°C-95°C, and the sodium carbonate solution is slowly added to the purified lithium solution, stirred, and filtered to obtain crude lithium carbonate.

[0045] (10) Carbon fractionation of crude lithium carbonate. Specifically, the process includes: adding water to crude lithium carbonate to form a slurry, wherein the mass ratio of water to crude lithium carbonate is (5-25):1; introducing CO2 into the slurry at a temperature of 20°C-40°C to dissolve the crude lithium carbonate into lithium bicarbonate, and then filtering to remove insoluble matter to obtain a filtrate; passing the filtrate through a specific macroporous chelating ion exchange resin to perform deep impurity removal to remove trace amounts of calcium, magnesium and heavy metals in the filtrate, and controlling the ion concentration of Ca, Mg, Fe, Ni, Cu, etc. to less than 5 mg / L, thereby obtaining a purified lithium bicarbonate solution.

[0046] (11) The purified lithium bicarbonate solution is heated to 80°C-90°C for crystallization to precipitate lithium carbonate.

[0047] (12) Adding water to the precipitated lithium carbonate for slurry preparation and washing, and then drying the washed lithium carbonate to obtain battery-grade lithium carbonate. The mass ratio of water in the slurry preparation and washing to the precipitated lithium carbonate is (3-10):1.

[0048] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, the conditions are carried out according to conventional conditions or manufacturer recommendations. The reagents or instruments used are not specified by the manufacturer and are conventional products that can be purchased commercially.

[0049] Example 1 This embodiment provides a method for enhancing the extraction of valuable components from solid waste using a composite chlorinating agent, specifically comprising: (1) The lithium-rich aluminum electrolyte waste slag produced by aluminum electrolysis was crushed and finely ground so that the residue after fine grinding passed through a 100-mesh sieve had a sieve residue of 19%. After testing, the mass proportion of Li in the lithium-containing waste slag was 2.14%.

[0050] (2) Sodium chloride and calcium chloride are mixed in a molar ratio of 1:1, and water is added to dissolve the mixture. The dissolved composite chlorinating agent solution is then added to the finely ground waste slag and mixed evenly. The mixture is granulated using a disc granulator to obtain green pellets of approximately 10 mm in size. The molar ratio of Cl in the composite chlorinating agent to Li in the finely ground waste slag is 3:1.

[0051] (3) The green pellets obtained in step (2) are dried at 180°C for 5 hours to reduce the moisture content of the green pellets to ≤0.5 wt%, and then calcined in a rotary kiln at 520°C for 2 hours to obtain cooked pellets. The cooled cooked pellets are crushed and finely ground to obtain a finely ground powder with a -100 mesh content of 85.3%.

[0052] (4) The finely ground pellet powder from step (3) was added to hydrochloric acid for leaching, and the pH value of the solution was controlled to be 3.5 during the leaching process, wherein the liquid-to-solid ratio was 5:1. After leaching at 50°C for 3 hours, the solution was filtered to obtain a lithium-containing leachate and a leachate residue. After testing, the leachate residue contained 0.25% lithium, the lithium concentration in the lithium-containing leachate was 3.75 g / L, and the lithium leaching rate based on the slag was 92.55%.

[0053] (5) The lithium-containing leachate obtained in step (4) is added to the leaching residue for cyclic leaching. The temperature and time of each leaching are the same as those in step (4). After 6 cycles, the leaching solution is filtered to obtain a high-lithium leachate with a lithium concentration of 21.83 g / L.

[0054] (6) The pH value of the high-lithium leaching solution obtained in step (5) is adjusted to 6, and a first-stage precipitation and impurity removal is performed to obtain a precipitate containing aluminum and iron and a de-impurity liquid. The de-impurity liquid is then defluorinated using a resin, and the pH value of the solution is further adjusted to 11. The second-stage precipitation and impurity removal is then performed to obtain a precipitate containing calcium and magnesium and a purified lithium liquid.

[0055] (7) The purified lithium solution obtained in step (6) is heated to 90°C. At the same time, industrial-grade sodium carbonate is prepared into a saturated sodium carbonate solution, which is filtered to remove insoluble matter and then treated with resin to obtain a purified sodium carbonate solution, which is also heated to 90°C. The 90°C sodium carbonate solution is slowly added to the 90°C purified lithium solution, stirred evenly, cooled, and filtered to obtain crude lithium carbonate.

[0056] (8) The crude lithium carbonate obtained in step (7) is slurried with water, wherein the mass ratio of water to crude lithium carbonate is 10:1, and the temperature is raised to 40°C. CO2 is then introduced to fully dissolve the crude lithium carbonate in the slurry, and the insoluble matter is removed by precise filtration. The filtrate is deeply impurized by passing it through a specific macroporous chelating ion exchange resin to remove trace calcium, magnesium and heavy metal elements. The concentrations of Ca, Mg, Fe, Ni and Cu ions in the purified lithium bicarbonate solution are 4.6 mg / L, 1.2 mg / L, 1.41 mg / L, 3.13 mg / L and 0.5 mg / L, respectively.

[0057] (9) The purified lithium bicarbonate solution obtained in step (8) is heated to 90° C. for crystallization to precipitate lithium carbonate.

[0058] (10) The precipitated lithium carbonate is added with water for slurry preparation and washing, wherein the mass ratio of water to lithium carbonate is 3:1, and then the washed and filtered lithium carbonate is dried to obtain battery-grade lithium carbonate.

[0059] Example 2 This embodiment provides a method for enhancing the extraction of valuable components from solid waste using a composite chlorinating agent, which is the same as the process in Example 1, except that: In step (1), lithium-containing waste cathodes from the aluminum electrolysis industry are used as lithium-containing waste slag for crushing and fine grinding, and the mass proportion of Li in the lithium-containing waste slag is 1.24%; In step (2), magnesium chloride and calcium chloride in a molar ratio of 1:1 are used as a composite chlorinating agent; The calcination temperature in step (3) is 500°C; The lithium concentration in the lithium-containing leachate obtained in step (4) was 2.08 g / L, and the slag-based lithium leaching rate was 91.3%. After 8 cycles of leaching, the solution was filtered to obtain a high-lithium leachate with a lithium concentration of 16.57 g / L. The lithium solution was purified according to the lithium solution purification steps of Example 1 to obtain battery-grade lithium carbonate.

[0060] Example 3 This embodiment provides a method for enhancing the extraction of valuable components from solid waste using a composite chlorinating agent, which is the same as the process in Example 1, except that: In step (1), lithium-containing glass waste from the glass production industry is crushed and finely ground as lithium-containing waste slag, and the mass proportion of Li in the lithium-containing waste slag is 2.25%; In step (2), potassium chloride, calcium chloride and magnesium chloride in a molar ratio of 6.5:0.3:3.2 are used as a composite chlorinating agent; The calcination temperature in step (3) is 550°C; In step (4), the pH of the solution was controlled to be 3.0 during the leaching process. The lithium concentration in the obtained lithium-containing leachate was 4.03 g / L, and the lithium slag leaching rate was 95.2%. After 5 cycles of leaching, the solution was filtered to obtain a high-lithium leachate with a lithium concentration of 20.23 g / L. The lithium solution was purified according to the lithium solution purification steps of Example 1 to obtain battery-grade lithium carbonate.

[0061] Comparative Example 1 This comparative example provides a method for extracting valuable components from solid waste by strengthening the use of a composite chlorinating agent. The process is the same as that of Example 1, except that: In step (2), calcium chloride alone is used as the chlorinating agent; The calcination temperature in step (3) is 650°C; In step (4), the pH of the solution was controlled to be 3.5 during the leaching process. The lithium concentration in the obtained lithium-containing leachate was 2.76 g / L, and the lithium slag leaching rate was 65.8%. After 7 cycles of leaching, the solution was filtered to obtain a high-lithium leachate with a lithium concentration of 18.69 g / L. The lithium solution was purified according to the lithium solution purification steps of Example 1 to obtain battery-grade lithium carbonate.

[0062] It can be seen from the above comparative examples that the lithium recovery effect is still poor when using only calcium chloride even at higher temperatures.

[0063] Comparative Example 2 This comparative example provides a method for extracting valuable components from solid waste by strengthening the use of a composite chlorinating agent. The process is the same as that of Example 3, except that: In step (2), potassium chloride, calcium chloride and magnesium chloride are mixed in a molar ratio of 6.5:0.3:3.2, and then directly mixed with the finely ground lithium-containing waste to obtain a mixed material without granulation; The mixture obtained in step (3) is directly fed into a rotary kiln and calcined at 550°C; In step (4), the pH value of the solution during the leaching process is controlled to be 3.0, the lithium concentration in the obtained lithium-containing leachate is 1.63 g / L, and the lithium slag leaching rate is 85.4%; after 8 cycles of leaching, the lithium-containing leachate with a lithium concentration of 12.57 g / L is obtained by filtration.

[0064] It can be seen from the above comparative examples that without granulation, the slag leaching rate of lithium is reduced. The experiment also found that the ring formation phenomenon in the rotary kiln is serious, and the high temperature causes part of the lithium chloride to volatilize into the flue gas.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

[0066] Furthermore, those skilled in the art will appreciate that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and to form different embodiments. For example, any of the above-described claimed embodiments may be used in any combination. The information disclosed in this background section is intended solely to enhance understanding of the overall background of this application and should not be construed as an admission or any form of implication that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for extracting valuable components from solid waste by strengthening the use of a composite chlorinating agent, characterized in that: include: mixing lithium-containing solid waste with a composite chlorinating agent, pelletizing, and drying to obtain green pellets; roasting the raw pellets to obtain cooked pellets; The cooked pellets are subjected to low-acid leaching and solid-liquid separation to obtain a lithium-containing leachate and a leach residue, the lithium-containing leachate is used to circulately leach the leach residue, and solid-liquid separation is performed to obtain a high-lithium leachate; sodium carbonate is added to the high-lithium leachate to carry out a lithium precipitation reaction, and solid-liquid separation is performed to obtain crude lithium carbonate; The crude lithium carbonate is purified and crystallized to obtain battery-grade lithium carbonate.

2. The method for extracting valuable components from solid waste by composite chlorinating agent enhancement according to claim 1, wherein: The lithium-containing solid waste includes at least one of: lithium-containing battery waste residue, lithium-aluminum electrolyte, lithium-containing waste cathode, and lithium-containing waste glass; and / or, the lithium-containing solid waste comprises solid waste in the form of LiF; And / or, the mass proportion of Li in the lithium-containing solid waste is 0.01%-7%; And / or, the composite chlorinating agent includes at least two of calcium chloride, magnesium chloride, ferric chloride, ferrous chloride, ammonium chloride, cupric chloride, cuprous chloride, zinc chloride, lead chloride, aluminum chloride, and carbon tetrachloride; And / or, the composite chlorinating agent includes a binary system composite chlorinating agent or a multi-component system composite chlorinating agent.

3. The method for extracting valuable components from solid waste by composite chlorinating agent enhancement according to claim 2, wherein: The binary system composite chlorinating agent includes: magnesium chloride and calcium chloride in a molar ratio of 1:1, sodium chloride and calcium chloride in a molar ratio of 1:1, potassium chloride and calcium chloride in a molar ratio of 1:4, or potassium chloride and magnesium chloride in a molar ratio of 2:3; And / or, the composite chlorinating agent of the multi-component system includes: potassium chloride, calcium chloride and magnesium chloride in a molar ratio of 6.5:0.3:3.2, or potassium chloride, calcium chloride and magnesium chloride in a molar ratio of 2:3.5:4.

5.

4. The method for extracting valuable components from solid waste by strengthening the use of a composite chlorinating agent as claimed in claim 1, wherein: The method of mixing with a composite chlorinating agent and pelletizing comprises: Mixing the composite chlorinating agent with the lithium-containing solid waste, and then adding water to perform the pelletizing; Alternatively, the composite chlorinating agent is dissolved in water, and then the lithium-containing solid waste raw material is added to perform the mixing and pelletizing; The mass of the water is 10%-25% of the mass of the lithium-containing solid waste.

5. The method for extracting valuable components from solid waste by composite chlorinating agent enhancement according to claim 1, wherein: The size of the green pellets is 5mm-15mm; And / or, the drying comprises: drying the green pellets after pelletization at 80° C.-200° C. for 0.5 h-7 h to obtain dry green pellets with a water content of ≤0.5 wt %; And / or, the calcination temperature is 400°C-700°C, and the calcination time is 1h-3h; And / or, before the cooked pellets are subjected to low-acid leaching, the method further comprises: crushing and fine-grinding the cooked pellets to obtain pellet powder, wherein the pellet powder has a sieve residue of less than 50% when passing through a 100-mesh sieve.

6. The method for enhancing the extraction of valuable components from solid waste with a composite chlorinating agent according to claim 1, wherein: The acid used in the low-acid leaching includes at least one of sulfuric acid and hydrochloric acid; and / or, the liquid-to-solid ratio of the low-acid leaching is (3-6):1; And / or, the leaching time of the low-acid leaching is 2h-4h, and the leaching temperature is 20°C-60°C; and / or, the pH value of the lithium-containing leachate is 3-6; And / or, the number of cycles of the cyclic leaching is 2 to 8 times; And / or, the lithium concentration in the high-lithium leaching solution is greater than 15 g / L.

7. The method for extracting valuable components from solid waste enhanced by a composite chlorinating agent according to claim 1, wherein: Before the high-lithium leachate is subjected to lithium precipitation reaction, the process further includes: adjusting the pH value of the high-lithium leachate to 6-8, performing a first-stage precipitation and impurity removal to obtain a first-stage purified lithium solution; performing a resin defluorination treatment on the impurity-removed solution to obtain a defluorinated lithium solution; adjusting the pH value of the defluorinated lithium solution to 10-11, performing a second-stage precipitation and impurity removal to obtain a purified lithium solution; And / or, before the sodium carbonate is subjected to lithium precipitation reaction, the method further comprises: preparing the sodium carbonate into a saturated sodium carbonate solution, and performing resin purification treatment to obtain a purified sodium carbonate solution; And / or, the temperature of the lithium precipitation reaction is 80° C.-95° C.; And / or, the crude lithium carbonate is purified and crystallized, including: preparing the crude lithium carbonate into a slurry, introducing CO2 into the slurry, separating the solid and liquid, and obtaining a filtrate; deeply removing impurities from the filtrate to obtain a lithium bicarbonate solution; heating the lithium bicarbonate solution for crystallization to precipitate lithium carbonate.

8. The method for extracting valuable components from solid waste enhanced by a composite chlorinating agent according to claim 7, wherein: The mass ratio of water in the slurry to the crude lithium carbonate is (10-25):1; and / or, when the CO2 is introduced, the temperature of the slurry is 20°C-40°C; And / or, the deep impurity removal comprises: treating the filtrate with a macroporous chelating ion exchange resin, so that the concentration of impurity ions in the obtained lithium bicarbonate solution is less than 5 mg / L; And / or, the temperature of the heating crystallization is 80°C-90°C; And / or, after the lithium carbonate is precipitated, the method further includes: adding water to the lithium carbonate to prepare a slurry for washing, and then drying the washed lithium carbonate to obtain the battery-grade lithium carbonate.

9. The method for enhancing the extraction of valuable components from solid waste with a composite chlorinating agent according to any one of claims 1 to 8, wherein: The molar ratio of the Li element in the lithium-containing solid waste to the Cl element in the composite chlorinating agent is 1:(1-10).

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