Method for resource utilization of fluorine-containing solid waste in lithium battery recovery process

Abstract

The invention discloses a method for resource utilization of fluorine-containing solid waste in a lithium battery recovery process. The method comprises eight working procedures of wet grinding and alkaline conversion, acid leaching, roasting, wet grinding and leaching, fluorine and acid regulation, first evaporative crystallization, neutralization and second evaporative crystallization. Compared with the prior art, the method for recycling the fluorine-containing solid waste in the lithium battery recycling process has the advantages that fluorine ions and magnesium ions are efficiently recycled, and sustainable utilization of resources is achieved.

Description

Technical Field

[0001] The present invention relates to the field of solid waste recycling, and in particular to a method for resource utilization of fluorine-containing solid waste in a lithium battery recycling process. Background Art

[0002] In recent years, lithium-ion batteries have developed rapidly due to their advantages such as high energy density, high open-circuit voltage, and light weight. They have quickly occupied the consumer electronics market and expanded to the fields of energy storage devices and electric vehicles. As the production and use of lithium-ion batteries have grown exponentially, their manufacture and disposal have become hot issues of economic and environmental concern. The service life of lithium batteries is generally 3-5 years, and then they enter the scrap stage. The recycling volume of lithium batteries is huge and has potential pollution. During the recycling process of lithium-ion batteries, fluoride in the electrolyte is extracted and forms fluorine-containing solid waste. The main components of fluorine-containing solid waste include calcium fluoride and magnesium fluoride. The accumulation and treatment of fluorine-containing solid waste will not only occupy a large amount of land resources, but also there is a risk of rainwater leaching causing harmful substances to penetrate into the soil, polluting groundwater and the surrounding environment. However, fluorine-containing solid waste contains rich resources and has important recycling value. Therefore, it is imperative to harmlessly treat and recycle fluorine-containing solid waste.

[0003] At present, commonly used technologies can recover substances such as calcium fluoride, calcium chloride and quartz from fluorine-containing solid waste. For example, a patent discloses a method for extracting calcium fluoride from fluorine-containing solid waste from which carbonates have been removed. The method includes leaching the fluorine-containing solid waste with hydrofluoric acid, separating the filtrate from the filter residue, and then leaching and drying the filter residue to obtain the finished calcium fluoride product. In addition, there is a patent that discloses a method for obtaining high-purity quartz from fluorine-containing solid waste. By leaching the fluorine-containing solid waste with hydrofluoric acid and adding a dissolving agent, the continuous dissolution reaction of silicon is blocked, thereby obtaining quartz of higher purity. It can be seen that the fluorine-containing solid waste generated in the lithium-ion battery recycling process has rich fluorine resources, specifically including calcium fluoride, magnesium fluoride and other complex fluorides, but the current fluorine resource recovery rate in fluorine-containing solid waste is still low, and the technology for efficiently recovering fluoride from fluorine-containing solid waste is still in its infancy.

[0004] Therefore, how to provide a method for resource utilization of fluorine-containing solid waste in the lithium battery recycling process, so that after the fluorine-containing solid waste of lithium batteries is treated by this method, all fluorides in the fluorine-containing solid waste can be efficiently converted into sodium fluoride and cryolite, and the technical effect of sustainable utilization of resources can be achieved, is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] In view of the problems existing in the prior art, the technical problem to be solved by the present invention is to provide a method for resource utilization of fluorine-containing solid waste in the lithium battery recycling process, so that after the fluorine-containing solid waste of lithium batteries is treated by this method, all fluorides in the fluorine-containing solid waste can be efficiently converted into sodium fluoride and cryolite, thereby achieving the technical effect of sustainable utilization of resources.

[0006] To achieve the above-mentioned purpose, the present invention provides a method for resource utilization of fluorine-containing solid waste in a lithium battery recycling process, and the method for resource utilization of fluorine-containing solid waste in a lithium battery recycling process comprises: S1, wet grinding alkali conversion: adding sodium hydroxide to the fluorine-containing solid waste for wet grinding alkali conversion, solid-liquid separation, and obtaining alkali conversion slag and alkali conversion liquid; S2, acid leaching: acid leaching the alkali conversion slag obtained in S1 with a sulfuric acid aqueous solution, solid-liquid separation, and obtaining acid leaching slag and magnesium sulfate acid leaching liquid; S3, roasting: adding aluminum sulfate to the acid leaching slag obtained in S2, mixing evenly, and roasting to obtain roasting slag; S4, wet grinding leaching: the S3 The calcined slag obtained in S4 is wet-milled and leached, and the solid-liquid is separated to obtain wet-milled leaching slag and wet-milled leaching liquid; S5, fluorine and acid adjustment: hydrofluoric acid and sodium fluoride are added to the wet-milled leaching liquid obtained in S4 to obtain sodium sulfate and cryolite; S6, first evaporation and crystallization: the magnesium sulfate acid leaching liquid obtained in S2 is evaporated and crystallized to obtain magnesium sulfate and magnesium sulfate crystallization mother liquor; S7, neutralization: the alkali-converted liquid obtained in S1 is neutralized with hydrofluoric acid to obtain a neutralized liquid; S8, second evaporation and crystallization: the neutralized liquid obtained in S7 is evaporated and crystallized to obtain sodium fluoride and sodium fluoride crystallization mother liquor.

[0007] In the first aspect, in S1, the amount of sodium hydroxide added is 1.5 to 2 times the theoretical reaction molar amount of fluoride in the fluorine-containing solid waste, the alkali conversion solvent of the wet milling alkali conversion is water, the ball-to-material ratio of the wet milling alkali conversion is 8 to 12, the liquid-to-solid ratio of the wet milling alkali conversion is 1 to 4 mL / g, the ball milling time of the wet milling alkali conversion is 0.5 to 1 hour, and the ball milling speed of the wet milling alkali conversion is 400 to 800 rpm.

[0008] In the first aspect, in S2, the amount of the sulfuric acid aqueous solution added is 1.5 to 2 times the theoretical reaction molar amount of calcium and magnesium in the alkali-converted slag, the acid leaching temperature is 25 to 50°C, the acid leaching time is 0.2 to 2 hours, and the liquid-to-solid ratio of the sulfuric acid aqueous solution to the alkali-converted slag is 8 to 14 mL / g.

[0009] In the first aspect, in S3, the amount of aluminum sulfate added is 1.5 to 2 times the theoretical reaction molar amount of fluoride in the acid leaching residue, the roasting temperature is 400 to 800° C., and the roasting time is 2 to 6 hours.

[0010] In the first aspect, in S4, the liquid-to-solid ratio of the leaching solvent of the wet milling leaching to the roasted slag is 8-12 mL / g, the leaching solvent of the wet milling leaching is water, the ball-to-material ratio of the wet milling leaching is 4-8, the ball milling time of the wet milling leaching is 0.5-1.5 hours, and the ball milling speed of the wet milling leaching is 100-300 rpm.

[0011] In the first aspect, in S4, the wet-ground leached residue is used as a building material.

[0012] In the first aspect, the step of adding hydrofluoric acid and sodium fluoride to the wet-milled leachate obtained in S4 to obtain sodium sulfate and cryolite specifically includes: adding hydrofluoric acid and sodium fluoride to the wet-milled leachate obtained in S4 until the molar ratio of sodium ion, aluminum ion, and fluoride ion is (3-4):1:(6-8), thereby obtaining sodium sulfate and cryolite.

[0013] In the first aspect, in S5, the sodium sulfate is centrally processed.

[0014] In the first aspect, in S6, the magnesium sulfate crystallization mother liquor is recycled to the acid leaching process in S2.

[0015] In the first aspect, in S8, the sodium fluoride crystallization mother liquor is recycled to the wet grinding alkali conversion process in S1.

[0016] Beneficial effects:

[0017] The method for resource utilization of fluorine-containing solid waste in a lithium battery recycling process of the present invention is used to treat the fluorine-containing solid waste generated in the lithium battery recycling process and realize efficient conversion of fluoride into sodium fluoride and cryolite, thereby realizing sustainable utilization of resources. The fluorine-containing solid waste generated in the process of lithium battery recovery mainly contains calcium fluoride and magnesium fluoride. The present invention adds sodium hydroxide to the fluorine-containing solid waste for wet grinding and alkali conversion, and magnesium fluoride reacts with sodium hydroxide to generate magnesium hydroxide. The main components of the alkali conversion slag are magnesium hydroxide and calcium fluoride, and the alkali conversion liquid mainly contains sodium ions, fluoride ions and hydroxide ions. The alkali conversion liquid is neutralized with hydrofluoric acid, and then evaporated and crystallized to obtain sodium fluoride and sodium fluoride crystallization mother liquor. The obtained sodium fluoride crystallization mother liquor is reused in the wet grinding and alkali conversion process to maximize the recovery of fluoride ions; the alkali conversion slag is acid-leached with sulfuric acid aqueous solution to obtain acid leaching slag and magnesium sulfate acid leaching liquid. The main component of the acid leaching slag is calcium fluoride, and the magnesium sulfate acid leaching liquid mainly contains sulfate ions and magnesium ions. The magnesium sulfate acid leaching liquid is evaporated and crystallized to obtain magnesium sulfate and magnesium sulfate crystallization mother liquor. The obtained magnesium sulfate crystallization mother liquor is reused in the acid leaching process to maximize the recovery of magnesium ions; aluminum sulfate is added to the acid leaching slag, and then roasted to obtain calcium sulfate. The invention discloses a method for recycling fluorine-containing solid waste in a lithium battery recycling process, and a method for recycling fluorine-containing solid waste in a lithium battery recycling process. The method comprises the steps of: preparing a calcined slag containing fluorine, a fluoride and a sulfate ion and wet-grinding and leaching the calcined slag to obtain wet-grinding leaching slag and wet-grinding leaching liquid, wherein the wet-grinding leaching slag is mainly calcium sulfate and can be used as a building material, thereby realizing resource recycling; the wet-grinding leaching liquid mainly contains aluminum ions, fluoride and sulfate ions, and hydrofluoric acid and sodium fluoride are added to the wet-grinding leaching liquid to make the molar amounts of sodium ions, aluminum ions and fluoride ions reach a certain ratio, and after the reaction is completed, cryolite and sodium sulfate solution are generated, and the sodium sulfate solution is centrally treated; in summary, the method for recycling fluorine-containing solid waste in a lithium battery recycling process of the present invention realizes the efficient recovery of fluoride ions and magnesium ions, and in addition, cryolite is obtained, thereby realizing sustainable resource utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 The present invention is a flow chart of a method for resource utilization of fluorine-containing solid waste in a lithium battery recycling process. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of this specification to clearly and completely describe the technical solutions in the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0021] Embodiment 1

[0022] like Figure 1 As shown, the present embodiment 1 provides a method for resource utilization of fluorine-containing solid waste in a lithium battery recycling process, and the method for resource utilization of fluorine-containing solid waste in a lithium battery recycling process includes: S1, wet grinding alkali conversion: adding sodium hydroxide to the fluorine-containing solid waste for wet grinding alkali conversion, solid-liquid separation, and obtaining alkali conversion slag and alkali conversion liquid; S2, acid leaching: acid leaching the alkali conversion slag obtained in S1 with a sulfuric acid aqueous solution, solid-liquid separation, to obtain acid leaching slag and magnesium sulfate acid leaching liquid; S3, roasting: adding aluminum sulfate to the acid leaching slag obtained in S2, mixing evenly, and roasting to obtain roasting slag; S4, wet grinding leaching: the alkali conversion slag obtained in S3 is leached The calcined slag is wet-milled and leached, and the solid-liquid is separated to obtain wet-milled leaching slag and wet-milled leaching liquid; S5, fluorine and acid adjustment: hydrofluoric acid and sodium fluoride are added to the wet-milled leaching liquid obtained in S4 to obtain sodium sulfate and cryolite; S6, first evaporation and crystallization: the magnesium sulfate acid leaching liquid obtained in S2 is evaporated and crystallized to obtain magnesium sulfate and magnesium sulfate crystallization mother liquor; S7, neutralization: the alkali-converted liquid obtained in S1 is neutralized with hydrofluoric acid to obtain a neutralized liquid; S8, second evaporation and crystallization: the neutralized liquid obtained in S7 is evaporated and crystallized to obtain sodium fluoride and sodium fluoride crystallization mother liquor.

[0023] The method for resource utilization of fluorine-containing solid waste in a lithium battery recycling process of the present invention is used to treat the fluorine-containing solid waste generated in the lithium battery recycling process and realize efficient conversion of fluoride into sodium fluoride and cryolite, thereby realizing sustainable utilization of resources. The fluorine-containing solid waste generated in the process of lithium battery recovery mainly contains calcium fluoride and magnesium fluoride. The present invention adds sodium hydroxide to the fluorine-containing solid waste for wet grinding and alkali conversion, and magnesium fluoride reacts with sodium hydroxide to generate magnesium hydroxide. The main components of the alkali conversion slag are magnesium hydroxide and calcium fluoride, and the alkali conversion liquid mainly contains sodium ions, fluoride ions and hydroxide ions. The alkali conversion liquid is neutralized with hydrofluoric acid, and then evaporated and crystallized to obtain sodium fluoride and sodium fluoride crystallization mother liquor. The obtained sodium fluoride crystallization mother liquor is reused in the wet grinding and alkali conversion process to maximize the recovery of fluoride ions; the alkali conversion slag is acid-leached with sulfuric acid aqueous solution to obtain acid leaching slag and magnesium sulfate acid leaching liquid. The main component of the acid leaching slag is calcium fluoride, and the magnesium sulfate acid leaching liquid mainly contains sulfate ions and magnesium ions. The magnesium sulfate acid leaching liquid is evaporated and crystallized to obtain magnesium sulfate and magnesium sulfate crystallization mother liquor. The obtained magnesium sulfate crystallization mother liquor is reused in the acid leaching process to maximize the recovery of magnesium ions; aluminum sulfate is added to the acid leaching slag, and then roasted to obtain calcium sulfate. The invention discloses a method for recycling fluorine-containing solid waste in a lithium battery recycling process, and a method for recycling fluorine-containing solid waste in a lithium battery recycling process. The method comprises the steps of: preparing a calcined slag containing fluorine, a fluoride and a sulfate ion and wet-grinding and leaching the calcined slag to obtain wet-grinding leaching slag and wet-grinding leaching liquid, wherein the wet-grinding leaching slag is mainly calcium sulfate and can be used as a building material, thereby realizing resource recycling; the wet-grinding leaching liquid mainly contains aluminum ions, fluoride and sulfate ions, and hydrofluoric acid and sodium fluoride are added to the wet-grinding leaching liquid to make the molar amounts of sodium ions, aluminum ions and fluoride ions reach a certain ratio, and after the reaction is completed, cryolite and sodium sulfate solution are generated, and the sodium sulfate solution is centrally treated; in summary, the method for recycling fluorine-containing solid waste in a lithium battery recycling process of the present invention realizes the efficient recovery of fluoride ions and magnesium ions, and in addition, cryolite is obtained, thereby realizing sustainable resource utilization.

[0024] In some possible implementations, in S1, the amount of sodium hydroxide added is 1.5 to 2 times the theoretical reaction molar amount of fluoride in the fluorine-containing solid waste, the alkali conversion solvent of the wet milling alkali conversion is water, the ball-to-material ratio of the wet milling alkali conversion is 8 to 12, the liquid-to-solid ratio of the wet milling alkali conversion is 1 to 4 mL / g, the ball milling time of the wet milling alkali conversion is 0.5 to 1 hour, and the ball milling speed of the wet milling alkali conversion is 400 to 800 rpm.

[0025] Specifically, magnesium fluoride in the fluorine-containing solid waste reacts with sodium hydroxide to obtain sodium hydroxide precipitate.

[0026] In some possible implementations, in S2, the amount of the aqueous sulfuric acid solution added is 1.5 to 2 times the theoretical reaction molar amount of calcium and magnesium in the alkali-converted slag, the acid leaching temperature is 25 to 50°C, the acid leaching time is 0.2 to 2 hours, and the liquid-to-solid ratio of the aqueous sulfuric acid solution to the alkali-converted slag is 8 to 14 mL / g.

[0027] Specifically, the main components of alkali-converted slag are magnesium hydroxide and calcium fluoride. A sulfuric acid aqueous solution is added for acid leaching. Magnesium hydroxide reacts with sulfuric acid to form magnesium sulfate, while calcium fluoride does not react with sulfuric acid.

[0028] In some possible implementations, in S3, the amount of aluminum sulfate added is 1.5 to 2 times the theoretical reaction molar amount of fluoride in the acid leaching residue, the roasting temperature is 400 to 800° C., and the roasting time is 2 to 6 hours.

[0029] Specifically, an excess amount of aluminum sulfate is added to the acid leaching residue for roasting to obtain calcium sulfate precipitate and a substance containing aluminum ions, fluoride ions and sulfate ions.

[0030] In some possible implementations, in S4, the liquid-to-solid ratio of the leaching solvent of the wet milling leaching to the roasted slag is 8-12 mL / g, the leaching solvent of the wet milling leaching is water, the ball-to-material ratio of the wet milling leaching is 4-8, the ball milling time of the wet milling leaching is 0.5-1.5 hours, and the ball milling speed of the wet milling leaching is 100-300 rpm; in S4, the wet milling leaching slag is used as building materials.

[0031] Specifically, the roasted slag mainly contains calcium sulfate precipitate and substances containing aluminum ions, fluoride ions and sulfate ions. After wet grinding and leaching, the calcium sulfate precipitate is separated and can be used as a building material, realizing the recycling of resources; the wet grinding leaching liquid contains aluminum ions, fluoride ions and sulfate ions.

[0032] In some possible implementations, the step of adding hydrofluoric acid and sodium fluoride to the wet-milled leachate obtained in S4 to obtain sodium sulfate and cryolite specifically includes: adding hydrofluoric acid and sodium fluoride to the wet-milled leachate obtained in S4 until the molar ratio of sodium ion, aluminum ion, and fluoride ion is (3-4):1:(6-8), thereby obtaining sodium sulfate and cryolite.

[0033] Specifically, the most efficient conversion to cryolite can be achieved by adjusting the molar amounts of sodium ions, aluminum ions, and fluoride ions in the wet grinding leachate to a certain ratio using hydrofluoric acid and sodium fluoride.

[0034] In some possible implementations, in S5, the sodium sulfate is centrally processed.

[0035] Specifically, the obtained sodium sulfate is centrally processed, which is environmentally friendly.

[0036] In some possible implementations, in S6, the magnesium sulfate crystallization mother liquor is recycled to the acid leaching process in S2; in S8, the sodium fluoride crystallization mother liquor is recycled to the wet grinding alkali conversion process in S1.

[0037] Specifically, the mother liquor of magnesium sulfate crystallization is recycled to the acid leaching process to achieve the maximum recovery of magnesium ions; the mother liquor of sodium fluoride crystallization is recycled to the wet grinding alkali conversion process to achieve the maximum recovery of fluoride ions.

[0038] In order to further illustrate the technical solution of the present application in detail to support the technical problem to be solved by the present application, the preparation method is described below by specific comparative examples and examples, such as implementation examples 1 to 4 and comparative examples 1 to 3.

[0039] Implementation Example 1

[0040] A method for resource utilization of fluorine-containing solid waste in a lithium battery recycling process, specifically comprising the following steps:

[0041] Wet milling and alkali conversion: adding sodium hydroxide to the fluorine-containing solid waste for wet milling and alkali conversion, separating the solid and the liquid, and obtaining alkali conversion residue and alkali conversion liquid; the amount of sodium hydroxide added is 1.6 times the theoretical reaction molar amount of fluoride in the fluorine-containing solid waste, the alkali conversion solvent of the wet milling and alkali conversion is water, the ball-to-material ratio of the wet milling and alkali conversion is 12, the liquid-to-solid ratio of the wet milling and alkali conversion is 4 mL / g, the ball milling time of the wet milling and alkali conversion is 1 hour, and the ball milling speed of the wet milling and alkali conversion is 800 rpm;

[0042] Acid leaching: the alkali-converted slag obtained in the wet grinding alkali-converted slag is acid-leached with an aqueous sulfuric acid solution, and the solid-liquid separation is performed to obtain the acid-leached slag and the magnesium sulfate acid leaching solution; the amount of the aqueous sulfuric acid solution added is 2 times the theoretical reaction molar amount of calcium and magnesium in the alkali-converted slag, the acid leaching temperature is 30° C., the acid leaching time is 0.6 hours, and the liquid-solid ratio of the aqueous sulfuric acid solution to the alkali-converted slag is 10 mL / g;

[0043] Calcination: adding aluminum sulfate to the acid leaching residue obtained in the acid leaching, mixing evenly, and calcining to obtain calcined residue; the amount of aluminum sulfate added is 1.6 times the theoretical reaction molar amount of fluoride in the acid leaching residue, the calcination temperature is 500° C., and the calcination time is 3 hours;

[0044] Wet milling leaching: wet milling leaching the roasted slag obtained in the acid leaching, solid-liquid separation, to obtain wet milling leaching slag and wet milling leaching liquid; the liquid-solid ratio of the leaching solvent of the wet milling leaching to the roasted slag is 10 mL / g, the leaching solvent of the wet milling leaching is water, the ball-to-material ratio of the wet milling leaching is 6, the ball milling time of the wet milling leaching is 1 hour, and the ball milling speed of the wet milling leaching is 200 rpm; the wet milling leaching slag is used as a building material;

[0045] Fluorine and acid adjustment: adding hydrofluoric acid and sodium fluoride to the wet grinding leachate obtained in the wet grinding leaching until the molar ratio of sodium ion, aluminum ion and fluoride ion is 3.2:1:6.2, to obtain sodium sulfate and cryolite;

[0046] First evaporation crystallization: the magnesium sulfate acid leaching solution obtained in the acid leaching is evaporated and crystallized to obtain magnesium sulfate and magnesium sulfate crystallization mother liquor; the magnesium sulfate crystallization mother liquor is reused in the acid leaching process;

[0047] Neutralization: neutralizing the alkali liquid obtained by the wet grinding alkali conversion with hydrofluoric acid to obtain a neutralized liquid;

[0048] Second evaporation crystallization: the neutralized solution obtained in the neutralization is evaporated and crystallized to obtain sodium fluoride and sodium fluoride crystallization mother liquor; the sodium fluoride crystallization mother liquor is recycled to the wet grinding alkali conversion process.

[0049] Implementation Example 2

[0050] A method for resource utilization of fluorine-containing solid waste in a lithium battery recycling process, specifically comprising the following steps:

[0051] Wet milling and alkali conversion: adding sodium hydroxide to the fluorine-containing solid waste for wet milling and alkali conversion, separating the solid and the liquid, and obtaining alkali conversion residue and alkali conversion liquid; the amount of sodium hydroxide added is 1.8 times the theoretical reaction molar amount of fluoride in the fluorine-containing solid waste, the alkali conversion solvent of the wet milling and alkali conversion is water, the ball-to-material ratio of the wet milling and alkali conversion is 12, the liquid-to-solid ratio of the wet milling and alkali conversion is 3 mL / g, the ball milling time of the wet milling and alkali conversion is 1 hour, and the ball milling speed of the wet milling and alkali conversion is 600 rpm;

[0052] Acid leaching: the alkali-converted slag obtained in the wet grinding alkali-converted slag is acid-leached with an aqueous sulfuric acid solution, and the solid-liquid separation is performed to obtain the acid-leached slag and the magnesium sulfate acid leaching solution; the amount of the aqueous sulfuric acid solution added is 2 times the theoretical reaction molar amount of calcium and magnesium in the alkali-converted slag, the acid leaching temperature is 40° C., the acid leaching time is 2 hours, and the liquid-solid ratio of the aqueous sulfuric acid solution to the alkali-converted slag is 14 mL / g;

[0053] Calcination: adding aluminum sulfate to the acid leaching residue obtained in the acid leaching, mixing evenly, and calcining to obtain calcined residue; the amount of aluminum sulfate added is twice the theoretical reaction molar amount of fluoride in the acid leaching residue, the calcination temperature is 800° C., and the calcination time is 6 hours;

[0054] Wet milling leaching: wet milling leaching the roasted slag obtained in the acid leaching, solid-liquid separation, to obtain wet milling leaching slag and wet milling leaching liquid; the liquid-solid ratio of the leaching solvent of the wet milling leaching to the roasted slag is 10 mL / g, the leaching solvent of the wet milling leaching is water, the ball-to-material ratio of the wet milling leaching is 6, the ball milling time of the wet milling leaching is 1.5 hours, and the ball milling speed of the wet milling leaching is 300 rpm; the wet milling leaching slag is used as a building material;

[0055] Fluorine and acid adjustment: adding hydrofluoric acid and sodium fluoride to the wet grinding leachate obtained in the wet grinding leaching until the molar ratio of sodium ion, aluminum ion and fluoride ion is 3.6:1:6.4, to obtain sodium sulfate and cryolite;

[0056] First evaporation crystallization: the magnesium sulfate acid leaching solution obtained in the acid leaching is evaporated and crystallized to obtain magnesium sulfate and magnesium sulfate crystallization mother liquor; the magnesium sulfate crystallization mother liquor is reused in the acid leaching process;

[0057] Neutralization: neutralizing the alkali liquid obtained by the wet grinding alkali conversion with hydrofluoric acid to obtain a neutralized liquid;

[0058] Second evaporation crystallization: the neutralized solution obtained in the neutralization is evaporated and crystallized to obtain sodium fluoride and sodium fluoride crystallization mother liquor; the sodium fluoride crystallization mother liquor is recycled to the wet grinding alkali conversion process.

[0059] Implementation Example 3

[0060] A method for resource utilization of fluorine-containing solid waste in a lithium battery recycling process, specifically comprising the following steps:

[0061] Wet milling and alkali conversion: adding sodium hydroxide to the fluorine-containing solid waste for wet milling and alkali conversion, separating the solid and the liquid, and obtaining alkali conversion residue and alkali conversion liquid; the amount of sodium hydroxide added is 1.9 times the theoretical reaction molar amount of fluoride in the fluorine-containing solid waste, the alkali conversion solvent of the wet milling and alkali conversion is water, the ball-to-material ratio of the wet milling and alkali conversion is 12, the liquid-to-solid ratio of the wet milling and alkali conversion is 3 mL / g, the ball milling time of the wet milling and alkali conversion is 0.8 hours, and the ball milling speed of the wet milling and alkali conversion is 500 rpm;

[0062] Acid leaching: the alkali-converted slag obtained in the wet grinding alkali-converted slag is acid-leached with an aqueous sulfuric acid solution, and the solid-liquid separation is performed to obtain the acid-leached slag and the magnesium sulfate acid leaching solution; the amount of the aqueous sulfuric acid solution added is 2 times the theoretical reaction molar amount of calcium and magnesium in the alkali-converted slag, the acid leaching temperature is 45° C., the acid leaching time is 1.5 hours, and the liquid-solid ratio of the aqueous sulfuric acid solution to the alkali-converted slag is 12 mL / g;

[0063] Calcination: adding aluminum sulfate to the acid leaching residue obtained in the acid leaching, mixing evenly, and calcining to obtain calcined residue; the amount of aluminum sulfate added is 1.9 times the theoretical reaction molar amount of fluoride in the acid leaching residue, the calcination temperature is 600° C., and the calcination time is 4 hours;

[0064] Wet milling leaching: wet milling leaching the roasted slag obtained in the acid leaching, solid-liquid separation, to obtain wet milling leaching slag and wet milling leaching liquid; the liquid-solid ratio of the leaching solvent of the wet milling leaching to the roasted slag is 12 mL / g, the leaching solvent of the wet milling leaching is water, the ball-to-material ratio of the wet milling leaching is 8, the ball milling time of the wet milling leaching is 1.5 hours, and the ball milling speed of the wet milling leaching is 250 rpm; the wet milling leaching slag is used as a building material;

[0065] Fluorine and acid adjustment: adding hydrofluoric acid and sodium fluoride to the wet grinding leachate obtained in the wet grinding leaching until the molar ratio of sodium ion, aluminum ion and fluoride ion is 3:1:6.6, to obtain sodium sulfate and cryolite;

[0066] First evaporation crystallization: the magnesium sulfate acid leaching solution obtained in the acid leaching is evaporated and crystallized to obtain magnesium sulfate and magnesium sulfate crystallization mother liquor; the magnesium sulfate crystallization mother liquor is reused in the acid leaching process;

[0067] Neutralization: neutralizing the alkali liquid obtained by the wet grinding alkali conversion with hydrofluoric acid to obtain a neutralized liquid;

[0068] Second evaporation crystallization: the neutralized solution obtained in the neutralization is evaporated and crystallized to obtain sodium fluoride and sodium fluoride crystallization mother liquor; the sodium fluoride crystallization mother liquor is recycled to the wet grinding alkali conversion process.

[0069] Implementation Example 4

[0070] A method for resource utilization of fluorine-containing solid waste in a lithium battery recycling process, specifically comprising the following steps:

[0071] Wet milling and alkali conversion: adding sodium hydroxide to the fluorine-containing solid waste for wet milling and alkali conversion, separating the solid and the liquid, and obtaining alkali conversion residue and alkali conversion liquid; the amount of sodium hydroxide added is 1.7 times the theoretical reaction molar amount of fluoride in the fluorine-containing solid waste, the alkali conversion solvent of the wet milling and alkali conversion is water, the ball-to-material ratio of the wet milling and alkali conversion is 8, the liquid-to-solid ratio of the wet milling and alkali conversion is 2 mL / g, the ball milling time of the wet milling and alkali conversion is 1 hour, and the ball milling speed of the wet milling and alkali conversion is 600 rpm;

[0072] Acid leaching: the alkali-converted slag obtained in the wet grinding alkali-converted slag is acid-leached with an aqueous sulfuric acid solution, and the solid-liquid separation is performed to obtain the acid-leached slag and the magnesium sulfate acid leaching solution; the amount of the aqueous sulfuric acid solution added is 1.6 times the theoretical reaction molar amount of calcium and magnesium in the alkali-converted slag, the acid leaching temperature is 45° C., the acid leaching time is 1.5 hours, and the liquid-solid ratio of the aqueous sulfuric acid solution to the alkali-converted slag is 12 mL / g;

[0073] Roasting: adding aluminum sulfate to the acid leaching residue obtained in the acid leaching, mixing evenly, and roasting to obtain roasted residue; the amount of aluminum sulfate added is twice the theoretical reaction molar amount of fluoride in the acid leaching residue, the roasting temperature is 500° C., and the roasting time is 3 hours;

[0074] Wet milling leaching: wet milling leaching the roasted slag obtained in the acid leaching, solid-liquid separation, to obtain wet milling leaching slag and wet milling leaching liquid; the liquid-solid ratio of the leaching solvent of the wet milling leaching to the roasted slag is 10 mL / g, the leaching solvent of the wet milling leaching is water, the ball-to-material ratio of the wet milling leaching is 8, the ball milling time of the wet milling leaching is 1.5 hours, and the ball milling speed of the wet milling leaching is 300 rpm; the wet milling leaching slag is used as a building material;

[0075] Fluorine and acid adjustment: adding hydrofluoric acid and sodium fluoride to the wet grinding leachate obtained in the wet grinding leaching until the molar ratio of sodium ion, aluminum ion and fluoride ion is 4:1:8, to obtain sodium sulfate and cryolite;

[0076] First evaporation crystallization: the magnesium sulfate acid leaching solution obtained in the acid leaching is evaporated and crystallized to obtain magnesium sulfate and magnesium sulfate crystallization mother liquor; the magnesium sulfate crystallization mother liquor is reused in the acid leaching process;

[0077] Neutralization: neutralizing the alkali liquid obtained by the wet grinding alkali conversion with hydrofluoric acid to obtain a neutralized liquid;

[0078] Second evaporation crystallization: the neutralized solution obtained in the neutralization is evaporated and crystallized to obtain sodium fluoride and sodium fluoride crystallization mother liquor; the sodium fluoride crystallization mother liquor is recycled to the wet grinding alkali conversion process.

[0079] Implementation Example 5

[0080] A method for resource utilization of fluorine-containing solid waste in a lithium battery recycling process, specifically comprising the following steps:

[0081] Wet milling and alkali conversion: adding sodium hydroxide to the fluorine-containing solid waste for wet milling and alkali conversion, separating the solid and the liquid, and obtaining alkali conversion residue and alkali conversion liquid; the amount of sodium hydroxide added is 1.5 times the theoretical reaction molar amount of fluoride in the fluorine-containing solid waste, the alkali conversion solvent of the wet milling and alkali conversion is water, the ball-to-material ratio of the wet milling and alkali conversion is 8, the liquid-to-solid ratio of the wet milling and alkali conversion is 1 mL / g, the ball milling time of the wet milling and alkali conversion is 0.5 hours, and the ball milling speed of the wet milling and alkali conversion is 400 rpm;

[0082] Acid leaching: the alkali-converted slag obtained in the wet grinding alkali-converted slag is acid-leached with an aqueous sulfuric acid solution, and the solid-liquid separation is performed to obtain the acid-leached slag and the magnesium sulfate acid leaching solution; the amount of the aqueous sulfuric acid solution added is 1.5 times the theoretical reaction molar amount of calcium and magnesium in the alkali-converted slag, the acid leaching temperature is 25° C., the acid leaching time is 0.2 hours, and the liquid-solid ratio of the aqueous sulfuric acid solution to the alkali-converted slag is 8 mL / g;

[0083] Calcination: adding aluminum sulfate to the acid leaching residue obtained in the acid leaching, mixing evenly, and calcining to obtain calcined residue; the amount of aluminum sulfate added is 1.5 times the theoretical reaction molar amount of fluoride in the acid leaching residue, the calcination temperature is 400° C., and the calcination time is 2 hours;

[0084] Wet milling leaching: wet milling leaching the roasted slag obtained in the acid leaching, solid-liquid separation, to obtain wet milling leaching slag and wet milling leaching liquid; the liquid-solid ratio of the leaching solvent of the wet milling leaching to the roasted slag is 8 mL / g, the leaching solvent of the wet milling leaching is water, the ball-to-material ratio of the wet milling leaching is 4, the ball milling time of the wet milling leaching is 0.5 hour, and the ball milling speed of the wet milling leaching is 100 rpm; the wet milling leaching slag is used as building materials;

[0085] Fluorine and acid adjustment: adding hydrofluoric acid and sodium fluoride to the wet grinding leachate obtained in the wet grinding leaching until the molar ratio of sodium ion, aluminum ion and fluoride ion is 3:1:6, to obtain sodium sulfate and cryolite;

[0086] First evaporation crystallization: the magnesium sulfate acid leaching solution obtained in the acid leaching is evaporated and crystallized to obtain magnesium sulfate and magnesium sulfate crystallization mother liquor; the magnesium sulfate crystallization mother liquor is reused in the acid leaching process;

[0087] Neutralization: neutralizing the alkali liquid obtained by the wet grinding alkali conversion with hydrofluoric acid to obtain a neutralized liquid;

[0088] Second evaporation crystallization: the neutralized solution obtained in the neutralization is evaporated and crystallized to obtain sodium fluoride and sodium fluoride crystallization mother liquor; the sodium fluoride crystallization mother liquor is recycled to the wet grinding alkali conversion process.

[0089] Comparative Example 1

[0090] A method for resource utilization of fluorine-containing solid waste in a lithium battery recycling process, specifically comprising the following steps:

[0091] Wet milling and alkali conversion: adding sodium hydroxide to the fluorine-containing solid waste for wet milling and alkali conversion, separating the solid and the liquid, and obtaining alkali conversion residue and alkali conversion liquid; the amount of sodium hydroxide added is 0.6 times the theoretical reaction molar amount of fluoride in the fluorine-containing solid waste, the alkali conversion solvent of the wet milling and alkali conversion is water, the ball-to-material ratio of the wet milling and alkali conversion is 8, the liquid-to-solid ratio of the wet milling and alkali conversion is 1 mL / g, the ball milling time of the wet milling and alkali conversion is 0.5 hours, and the ball milling speed of the wet milling and alkali conversion is 400 rpm;

[0092] Acid leaching: the alkali-converted slag obtained in the wet grinding alkali-converted slag is acid-leached with an aqueous sulfuric acid solution, and the solid-liquid separation is performed to obtain the acid-leached slag and the magnesium sulfate acid leaching solution; the amount of the aqueous sulfuric acid solution added is 1 times the theoretical reaction molar amount of calcium and magnesium in the alkali-converted slag, the acid leaching temperature is 25° C., the acid leaching time is 0.2 hours, and the liquid-solid ratio of the aqueous sulfuric acid solution to the alkali-converted slag is 8 mL / g;

[0093] Calcination: adding aluminum sulfate to the acid leaching residue obtained in the acid leaching, mixing evenly, and calcining to obtain calcined residue; the amount of aluminum sulfate added is 0.8 times the theoretical reaction molar amount of fluoride in the acid leaching residue, the calcination temperature is 400° C., and the calcination time is 2 hours;

[0094] Wet milling leaching: wet milling leaching the roasted slag obtained in the acid leaching, solid-liquid separation, to obtain wet milling leaching slag and wet milling leaching liquid; the liquid-solid ratio of the leaching solvent of the wet milling leaching to the roasted slag is 8 mL / g, the leaching solvent of the wet milling leaching is water, the ball-to-material ratio of the wet milling leaching is 4, the ball milling time of the wet milling leaching is 0.5 hour, and the ball milling speed of the wet milling leaching is 100 rpm; the wet milling leaching slag is used as building materials;

[0095] Fluorine and acid adjustment: adding hydrofluoric acid and sodium fluoride to the wet grinding leachate obtained in the wet grinding leaching until the molar ratio of sodium ion, aluminum ion and fluoride ion is 3:1:6, to obtain sodium sulfate and cryolite;

[0096] First evaporation crystallization: the magnesium sulfate acid leaching solution obtained in the acid leaching is evaporated and crystallized to obtain magnesium sulfate and magnesium sulfate crystallization mother liquor; the magnesium sulfate crystallization mother liquor is reused in the acid leaching process;

[0097] Neutralization: neutralizing the alkali liquid obtained by the wet grinding alkali conversion with hydrofluoric acid to obtain a neutralized liquid;

[0098] Second evaporation crystallization: the neutralized solution obtained in the neutralization is evaporated and crystallized to obtain sodium fluoride and sodium fluoride crystallization mother liquor; the sodium fluoride crystallization mother liquor is recycled to the wet grinding alkali conversion process.

[0099] Comparative Example 2

[0100] A method for resource utilization of fluorine-containing solid waste in a lithium battery recycling process, specifically comprising the following steps:

[0101] Wet milling and alkali conversion: adding sodium hydroxide to the fluorine-containing solid waste for wet milling and alkali conversion, separating the solid and the liquid, and obtaining alkali conversion residue and alkali conversion liquid; the amount of sodium hydroxide added is 1.2 times the theoretical reaction molar amount of fluoride in the fluorine-containing solid waste, the alkali conversion solvent of the wet milling and alkali conversion is water, the ball-to-material ratio of the wet milling and alkali conversion is 8, the liquid-to-solid ratio of the wet milling and alkali conversion is 1 mL / g, the ball milling time of the wet milling and alkali conversion is 0.5 hours, and the ball milling speed of the wet milling and alkali conversion is 400 rpm;

[0102] Acid leaching: the alkali-converted slag obtained in the wet grinding alkali-converted slag is acid-leached with an aqueous sulfuric acid solution, and the solid-liquid separation is performed to obtain the acid-leached slag and the magnesium sulfate acid leaching solution; the amount of the aqueous sulfuric acid solution added is 1 times the theoretical reaction molar amount of calcium and magnesium in the alkali-converted slag, the acid leaching temperature is 25° C., the acid leaching time is 0.2 hours, and the liquid-solid ratio of the aqueous sulfuric acid solution to the alkali-converted slag is 8 mL / g;

[0103] Calcination: adding aluminum sulfate to the acid leaching residue obtained in the acid leaching, mixing evenly, and calcining to obtain calcined residue; the amount of aluminum sulfate added is 1 times the theoretical reaction molar amount of fluoride in the acid leaching residue, the calcination temperature is 400° C., and the calcination time is 2 hours;

[0104] Wet milling leaching: wet milling leaching the roasted slag obtained in the acid leaching, solid-liquid separation, to obtain wet milling leaching slag and wet milling leaching liquid; the liquid-solid ratio of the leaching solvent of the wet milling leaching to the roasted slag is 8 mL / g, the leaching solvent of the wet milling leaching is water, the ball-to-material ratio of the wet milling leaching is 4, the ball milling time of the wet milling leaching is 0.5 hour, and the ball milling speed of the wet milling leaching is 100 rpm; the wet milling leaching slag is used as building materials;

[0105] Fluorine and acid adjustment: adding hydrofluoric acid and sodium fluoride to the wet grinding leachate obtained in the wet grinding leaching until the molar ratio of sodium ion, aluminum ion and fluoride ion is 3:1:6, to obtain sodium sulfate and cryolite;

[0106] First evaporation crystallization: the magnesium sulfate acid leaching solution obtained in the acid leaching is evaporated and crystallized to obtain magnesium sulfate and magnesium sulfate crystallization mother liquor; the magnesium sulfate crystallization mother liquor is reused in the acid leaching process;

[0107] Neutralization: neutralizing the alkali liquid obtained by the wet grinding alkali conversion with hydrofluoric acid to obtain a neutralized liquid;

[0108] Second evaporation crystallization: the neutralized solution obtained in the neutralization is evaporated and crystallized to obtain sodium fluoride and sodium fluoride crystallization mother liquor; the sodium fluoride crystallization mother liquor is recycled to the wet grinding alkali conversion process.

[0109] The effects of fluorinated gypsum in the glass thinning industry treated by implementation examples 1 to 4 and comparative examples 1 to 2 are compared as follows:

[0110] The recovery rate of fluorine in fluorine-containing solid waste, the purity of sodium fluoride, the recovery rate of magnesium, the purity of magnesium sulfate, and the purity of cryolite were tested, and the results are shown in Table 1.

[0111] Table 1 Results of recycling of fluorine-containing solid waste

[0112]

[0113] As can be seen from Table 1, the fluorine-containing solid waste generated in the lithium battery recycling process is treated by a method for resource utilization of fluorine-containing solid waste in the lithium battery recycling process of the present invention. In Implementation Examples 1 to 5, the fluorine recovery rate is 96.73%, which can reach 98.43%, and the magnesium recovery rate is above 97%, which can reach 98.48%. In the comparative examples, the highest fluorine recovery rate is 87.3%, and the highest magnesium recovery rate is 88.4%. Whether it is the fluorine recovery rate or the magnesium recovery rate, the comparative examples are lower than the implementation examples. The wet grinding alkali conversion process and the roasting process of the present invention have a great influence on the fluorine recovery rate and the magnesium recovery rate.

[0114] In summary, the method for resource utilization of fluorine-containing solid waste in a lithium battery recycling process of the present invention has the following advantages: 1. It realizes efficient recovery of fluoride ions and magnesium ions, and efficient purification of sodium fluoride and magnesium sulfate; 2. The obtained magnesium nitrate hexahydrate is recycled into the low-temperature molten salt conversion process to realize sustainable recycling of resources; 3. Cryolite is obtained at the end of the treatment, which has economic benefits.

[0115] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for resource utilization of fluorine-containing solid waste in the lithium battery recycling process, characterized in that: The method for resource utilization of fluorine-containing solid waste in the lithium battery recycling process comprises: S1. Wet grinding and alkali conversion: adding sodium hydroxide to the fluorine-containing solid waste for wet grinding and alkali conversion, and separating the solid and liquid to obtain alkali conversion residue and alkali conversion liquid; S2, acid leaching: acid leaching the alkali-converted slag obtained in S1 with a sulfuric acid aqueous solution, and solid-liquid separation to obtain acid leaching slag and magnesium sulfate acid leaching solution; S3, roasting: adding aluminum sulfate to the acid leaching residue obtained in S2, mixing evenly, and roasting to obtain roasted residue; S4, wet grinding and leaching: wet grinding and leaching the roasted slag obtained in S3, and separating the solid and liquid to obtain wet grinding leaching slag and wet grinding leaching liquid; S5, adjusting fluorine and acid: adding hydrofluoric acid and sodium fluoride to the wet grinding leachate obtained in S4 to obtain sodium sulfate and cryolite; S6, first evaporation crystallization: evaporating and crystallizing the magnesium sulfate acid leaching solution obtained in S2 to obtain magnesium sulfate and magnesium sulfate crystallization mother liquor; S7, neutralization: neutralizing the alkali liquid obtained in S1 with hydrofluoric acid to obtain a neutralized liquid; S8, second evaporation crystallization: the neutralized solution obtained in S7 is evaporated and crystallized to obtain sodium fluoride and sodium fluoride crystallization mother liquor.

2. The method for resource utilization of fluorine-containing solid waste in the lithium battery recycling process according to claim 1, characterized in that: In S1, the amount of sodium hydroxide added is 1.5 to 2 times the theoretical reaction molar amount of fluoride in the fluorine-containing solid waste, the alkali conversion solvent of the wet milling alkali conversion is water, the ball-to-material ratio of the wet milling alkali conversion is 8 to 12, the liquid-to-solid ratio of the wet milling alkali conversion is 1 to 4 mL / g, the ball milling time of the wet milling alkali conversion is 0.5 to 1 hour, and the ball milling speed of the wet milling alkali conversion is 400 to 800 rpm.

3. The method for resource utilization of fluorine-containing solid waste in the lithium battery recycling process according to claim 2, characterized in that: In S2, the amount of the sulfuric acid aqueous solution added is 1.5 to 2 times the theoretical reaction molar amount of calcium and magnesium in the alkali-converted slag, the acid leaching temperature is 25 to 50°C, the acid leaching time is 0.2 to 2 hours, and the liquid-to-solid ratio of the sulfuric acid aqueous solution to the alkali-converted slag is 8 to 14 mL / g.

4. A method for resource utilization of fluorine-containing solid waste in a lithium battery recycling process as claimed in claim 3, characterized in that: In S3, the amount of aluminum sulfate added is 1.5 to 2 times the theoretical reaction molar amount of fluoride in the acid leaching residue, the roasting temperature is 400 to 800° C., and the roasting time is 2 to 6 hours.

5. The method for resource utilization of fluorine-containing solid waste in the lithium battery recycling process according to claim 4, characterized in that: In S4, the liquid-to-solid ratio of the leaching solvent of the wet milling leaching to the roasted slag is 8-12 mL / g, the leaching solvent of the wet milling leaching is water, the ball-to-material ratio of the wet milling leaching is 4-8, the ball milling time of the wet milling leaching is 0.5-1.5 hours, and the ball milling speed of the wet milling leaching is 100-300 rpm.

6. The method for resource utilization of fluorine-containing solid waste in the lithium battery recycling process according to claim 5, characterized in that: In S4, the wet-milled leached residue is used as a building material.

7. A method for resource utilization of fluorine-containing solid waste in a lithium battery recycling process as claimed in claim 6, characterized in that: The step of adding hydrofluoric acid and sodium fluoride to the wet-milled leachate obtained in S4 to obtain sodium sulfate and cryolite specifically comprises: adding hydrofluoric acid and sodium fluoride to the wet-milled leachate obtained in S4 until the molar ratio of sodium ion, aluminum ion, and fluoride ion is (3-4):1:(6-8), thereby obtaining sodium sulfate and cryolite.

8. The method for resource utilization of fluorine-containing solid waste in the lithium battery recycling process according to claim 7, characterized in that: In S5, the sodium sulfate is centrally processed.

9. The method for resource utilization of fluorine-containing solid waste in the lithium battery recycling process according to claim 8, characterized in that: In S6, the magnesium sulfate crystallization mother liquor is recycled to the acid leaching process in S2.

10. The method for resource utilization of fluorine-containing solid waste in the lithium battery recycling process according to claim 9, characterized in that: In S8, the sodium fluoride crystallization mother liquor is recycled to the wet grinding alkali conversion process in S1.

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