Method for preparing high-purity lithium carbonate from waste lithium batteries

Abstract

The invention belongs to the technical field of waste lithium battery recovery, and discloses a method for preparing high-purity lithium carbonate by using waste lithium batteries. Comprising the following steps: S1, mixing black powder of the waste lithium battery with leaching acid 1, and carrying out selective leaching to obtain lithium-containing leachate and leaching residues; s2, an impurity removal agent 1 is added into the lithium-containing leachate, primary impurity removal is carried out, and lithium-containing impurity-removed liquid and impurity-removed slag 1 are obtained; s3, performing deep impurity removal on the lithium-containing impurity-removed solution by using an impurity removal agent 2 to obtain a lithium precipitation pre-solution and an impurity-removed solution 1; s4, dropwise adding the lithium precipitation pre-solution into the sodium carbonate solution to obtain high-purity lithium carbonate and a lithium precipitation mother solution; and S5, leaching acid in the lithium precipitation mother liquor is recycled. According to the method, the waste lithium batteries are selectively leached by using the organic acid, no waste gas is generated in the leaching process, the purity of the leachate is high, the impurity removal difficulty is low, and meanwhile, the leaching agent can be recycled, so that the preparation of high-purity lithium carbonate is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of waste lithium battery recycling, and more particularly to a method for preparing high-purity lithium carbonate by utilizing waste lithium batteries. Background Art

[0002] With the rapid development of global energy storage and mobile device power supply technologies, especially the explosive growth of electric vehicles and energy storage systems, lithium batteries, as a core energy storage and conversion technology, have led to a long-term growth in demand for lithium carbonate. Lithium carbonate is a key raw material for lithium battery production and is used to prepare lithium-ion battery cathode materials such as lithium cobalt oxide, lithium manganese oxide, ternary materials, and lithium iron phosphate. Currently, the lithium carbonate used in lithium battery production is primarily derived from salt lakes and lithium mineral resources. Natural reserves of lithium carbonate are very limited, highly regional, and scarce, making it a scarce resource.

[0003] Waste lithium batteries are rich in lithium. Recycling lithium not only has significant economic value, but also can alleviate resource shortages and reduce environmental pollution. It is an important part of promoting the sustainable development of the lithium battery industry.

[0004] The current process for extracting lithium carbonate from used lithium batteries is complex, requiring multiple steps including pretreatment, dissolution, extraction, and purification. As the number of used lithium batteries continues to increase, the demand for recycling technology is also increasing. In practice, improving the recovery rate and purity of lithium carbonate, reducing costs, and minimizing pollution are pressing challenges.

[0005] CN106505225A discloses a method for recovering lithium from waste lithium batteries to prepare battery-grade lithium carbonate. This method enriches lithium by precipitating lithium from a solution to produce lithium fluoride, but it also produces fluorine-containing wastewater and iron-aluminum slag. CN107475538A discloses a method for recovering valuable metals from the positive electrode material of waste lithium cobalt oxide batteries using citric acid and sodium thiosulfate. Due to the use of the inorganic salt sodium thiosulfate and the organic acid citric acid in this method, sulfur is also produced as a byproduct. CN116119690A discloses a method for selectively recovering lithium from waste lithium batteries. This method first leaches organic acid and then uses precipitation to remove metal ions such as nickel, cobalt, and manganese from the leachate. This method consumes a lot of alkali, and the precipitate contains a high content of lithium, resulting in a large loss of overall liquid alkali.

[0006] Therefore, developing more efficient, environmentally friendly, and low-cost recycling technologies to achieve resource-based and harmless treatment of used lithium batteries is an urgent challenge for those skilled in the art. For example, new extraction agents and separation technologies can be developed to increase metal recovery rates, while new treatment processes can be developed to reduce wastewater and exhaust emissions. Summary of the Invention

[0007] In view of this, the present invention provides a method for preparing high-purity lithium carbonate using waste lithium batteries, in which organic acid is used to selectively leach the waste lithium batteries. No waste gas is generated during the leaching process, the leachate has high purity, and the difficulty of impurity removal is small. At the same time, the leaching agent can be recycled, thereby realizing the preparation of high-purity lithium carbonate.

[0008] In order to achieve the above object, the present invention provides a method for preparing high-purity lithium carbonate using waste lithium batteries, comprising the following steps:

[0009] S1, mixing waste lithium battery black powder with leaching acid 1, performing selective leaching to obtain lithium-containing leachate and leaching residue;

[0010] S2, adding impurity remover 1 to the lithium-containing leachate to remove impurities once, to obtain a lithium-containing impurity-removed liquid and impurity-removed slag 1;

[0011] S3, using impurity remover 2 to deeply remove impurities from the lithium-containing impurity-removed liquid to obtain a lithium precipitation pre-liquid and impurity-removing liquid 1;

[0012] S4, adding the lithium precipitation pre-liquid dropwise to the sodium carbonate solution to obtain high-purity lithium carbonate and lithium precipitation mother liquor;

[0013] S5. Recover the leaching acid in the lithium precipitation mother liquor.

[0014] Preferably, in step S1, the waste lithium battery black powder is selected from one or more of lithium iron phosphate, ternary lithium, lithium cobalt oxide, lithium iron manganese phosphate, and lithium manganese oxide black powder; further preferably, the waste lithium battery black powder can be black powder that has been pre-treated by calcination or not.

[0015] Preferably, the leaching acid 1 is selected from one or more of organic acids, inorganic acids, and organic acid salts.

[0016] More preferably, the inorganic acid is sulfuric acid or hydrochloric acid, the organic acid is itaconic acid, and the organic acid salt is sodium itaconate.

[0017] Preferably, the sum of the molar concentrations of the leaching acid 1 is 0.2 mol / L-4.0 mol / L; further preferably, the sum of the molar concentrations is 1.0 mol / L-3.0 mol / L.

[0018] Preferably, the selective leaching is multi-stage countercurrent leaching, the leaching stages are 1-10, the reaction ratio is 2-50 mL / g, the temperature is 20-80° C., and the time is 2-240 min.

[0019] More preferably, the leaching stage is 2-6, the reaction ratio is 2-20 mL / g, the temperature is 20-50° C., and the time is 5-120 min.

[0020] Furthermore, when the waste lithium battery black powder is selected from ternary lithium or lithium cobalt oxide, the primary impurity removal in step S2 is not performed.

[0021] Preferably, in step S2, the impurity remover 1 is selected from one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, lithium hydroxide, lithium carbonate, ammonia water, and liquid ammonia, and the concentration of the impurity remover 1 is 20-200 g / L. More preferably, the concentration of the impurity remover 1 is 50-200 g / L.

[0022] Preferably, in step S2, the primary impurity removal is: adjusting the pH value of the lithium-containing leachate to 1.50-7.0 using the impurity remover 1 at 20-60°C.

[0023] Further preferably, the primary impurity removal is: adjusting the pH value of the lithium-containing leachate to 1.80-4.80 using the impurity remover 1 at 20-50°C.

[0024] Furthermore, before deep impurity removal, it is necessary to adjust the alkali to increase the pH. The alkali adjusting agent used can be sodium carbonate, sodium hydroxide, lithium carbonate, or lithium hydroxide. The alkali adjustment pH range is 4.50-10.0, and the alkali adjusting agent concentration is 50-200 g / L.

[0025] Preferably, in step S3, the impurity remover 2 is selected from TP207 resin, One of CH-93 resin, Haipu HP8 resin, and D860 resin.

[0026] Preferably, in step S3, the deep impurity removal adopts multi-stage series impurity removal to ensure the impurity removal effect, and the number of impurity removal stages is 2-6.

[0027] Furthermore, after the resin used for deep impurity removal is saturated, hydrochloric acid needs to be used for back extraction.

[0028] Preferably, in step S4, the concentration of the sodium carbonate solution is 180-220 g / L; the dropwise addition method is: at a reaction temperature of 80-98° C., controlling the flow rate of the lithium precipitation pre-liquid to be 0.1-0.5 times the volume of the sodium carbonate solution per hour.

[0029] Further preferably, the concentration of the sodium carbonate solution is 190-210 g / L; and the dropping temperature is 90-95°C.

[0030] Furthermore, in step S5, an inorganic acid is added to the lithium precipitation mother liquor to prepare itaconic acid, thereby completing the recovery of the leached acid.

[0031] Preferably, the inorganic acid is sulfuric acid, and the amount of sulfuric acid added is 1.1-1.5 of the sodium itaconate equivalent.

[0032] It can be seen from the above technical solutions that, compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The present invention uses organic acid to achieve selective leaching of lithium with a purity greater than 90%;

[0034] (2) The selective lithium leaching reaction conditions of the organic acid of the present invention are room temperature, low energy consumption cost, and conducive to industrial production;

[0035] (3) The present invention realizes the recycling of the leaching agent through the regeneration of itaconic acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0037] Figure 1 The process flow chart provided by the present invention. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] Example 1

[0040] A method for preparing high-purity lithium carbonate using waste lithium batteries:

[0041] The lithium nickel cobalt manganese oxide used was subjected to discharge crushing and then calcined at 700°C for 2.0 hours to pretreat the black powder. 0.5 mol / L itaconic acid was prepared as the leaching acid, and the leaching temperature was set at 30°C, the leaching ratio was 20 mL / g, and the leaching time was 60 minutes. To ensure the leaching rate, a three-stage countercurrent leaching process was used to produce a lithium-containing leachate and a leached residue. The lithium-containing leachate was adjusted to a pH of 4.80 using 50 g / L sodium hydroxide to remove iron and aluminum from the lithium-containing leachate. The impurities removed from the solution were removed using three TP207 resin columns in series to remove calcium, magnesium, aluminum, iron, nickel, cobalt, and manganese. Lithium carbonate precipitation was prepared by adding a lithium precipitation solution dropwise to a 200 g / L sodium carbonate solution at 95°C, maintaining a flow rate of 0.2 times the volume of the sodium carbonate solution per hour. The resulting lithium carbonate was dried to obtain high-purity lithium carbonate. The generated sodium itaconate is converted with sulfuric acid and then crystallized to precipitate itaconic acid.

[0042] The purity of lithium obtained by lithium leaching is 92.0%, and the purity of lithium carbonate generated is 99.68%.

[0043] Example 2

[0044] A method for preparing high-purity lithium carbonate using waste lithium batteries:

[0045] The lithium cobalt oxide used was crushed by discharge and then calcined at 700°C for 2.0 hours to pretreat the black powder. A mixture of 1.0 mol / L itaconic acid and 0.1 mol / L sulfuric acid was prepared as the leaching acid. The leaching temperature was set at 20°C, the leaching ratio was 8 mL / g, and the leaching time was 5 minutes. To ensure the leaching rate, a three-stage countercurrent leaching process was used to produce a lithium-containing leachate and a leached residue. The lithium-containing leachate was adjusted to a pH of 5.0 using 200 g / L sodium carbonate to remove iron and aluminum from the lithium-containing leachate. The impurities removed from the solution were removed using five columns of D860 resin in series to remove calcium, magnesium, aluminum, iron, and cobalt. Lithium carbonate precipitation was prepared by adding a lithium precipitation solution dropwise to a 200 g / L sodium carbonate solution at 98°C, maintaining a flow rate of 0.5 times the volume of the sodium carbonate solution per hour. The resulting lithium carbonate was dried to obtain high-purity lithium carbonate. The generated sodium itaconate is converted with sulfuric acid and then crystallized to precipitate itaconic acid.

[0046] The purity of lithium obtained by lithium leaching is 98.2%, and the purity of lithium carbonate generated is 99.86%.

[0047] Example 3

[0048] A method for preparing high-purity lithium carbonate using waste lithium batteries:

[0049] The lithium manganese iron phosphate used was crushed by discharge and then pretreated without calcination and passed through a 200-mesh sieve to pretreat the black powder. 0.8 mol / L itaconic acid was prepared as the leaching acid, with the leaching temperature set at 25°C, the leaching ratio at 4 mL / g, and the leaching time at 2 min. To ensure the leaching rate, a five-stage countercurrent leaching process was used. A lithium-containing leachate and leached residue were obtained. The lithium-containing leachate was adjusted to a pH of 5.0 using 50 g / L sodium carbonate to remove iron, aluminum, and phosphorus from the lithium-containing leachate. The impurities after impurity removal were removed using three D860 resin columns in series to remove calcium, magnesium, aluminum, iron, and cobalt. Lithium carbonate precipitation was prepared by adding a lithium precipitation solution dropwise to a 200 g / L sodium carbonate solution at 98°C, maintaining a flow rate of 0.1 times the volume of the sodium carbonate solution per hour. The resulting lithium carbonate was dried to obtain high-purity lithium carbonate. The resulting sodium itaconate was converted with sulfuric acid and crystallized to precipitate itaconic acid.

[0050] The purity of lithium obtained by lithium leaching is 90%, and the purity of lithium carbonate generated is 99.14%.

[0051] Example 4

[0052] A method for preparing high-purity lithium carbonate using waste lithium batteries:

[0053] The lithium nickel cobalt manganese oxide used was subjected to discharge crushing and then calcined at 700°C for 2 hours to pretreat the black powder. 2.2 mol / L itaconic acid was prepared as the leaching acid, with the leaching temperature set at 50°C, the leaching ratio at 30 mL / g, and the leaching time set at 240 minutes. To ensure the leaching rate, a 10-stage countercurrent leaching process was used to produce a lithium-containing leachate and leached residue. The lithium-containing leachate was adjusted to a pH of 6.0 using 100 g / L ammonia water to remove iron and aluminum from the lithium-containing leachate. The impurities removed from the solution were removed using three Haipu HP8 resin columns in series to remove calcium, magnesium, aluminum, iron, nickel, cobalt, and manganese. Lithium carbonate precipitation was prepared by adding a lithium precipitation precursor solution dropwise to a 200 g / L sodium carbonate solution at 80°C, maintaining a flow rate of 0.5 times the volume of the sodium carbonate solution per hour. The resulting lithium carbonate was dried to obtain high-purity lithium carbonate. The generated sodium itaconate is converted with sulfuric acid and then crystallized to precipitate itaconic acid.

[0054] Example 5

[0055] A method for preparing high-purity lithium carbonate using waste lithium batteries:

[0056] The lithium nickel cobalt manganese oxide used was subjected to discharge crushing and then calcined at 700°C for 2 hours to pretreat the black powder. 3.8 mol / L itaconic acid and 0.2 mol / L hydrochloric acid were prepared as the leaching acids. The leaching temperature was set at 80°C, the leaching ratio was 50 mL / g, and the leaching time was 120 minutes. To ensure the leaching rate, an eight-stage countercurrent leaching process was used to produce a lithium-containing leachate and a leached residue. The lithium-containing leachate was adjusted to a pH of 5.0 using 100 g / L sodium bicarbonate to remove iron and aluminum from the lithium-containing leachate. The impurities removed from the solution were removed using three TP207 resin columns in series to remove calcium, magnesium, aluminum, iron, nickel, cobalt, and manganese. Lithium carbonate precipitation was prepared by adding a lithium precipitation solution dropwise to an 85°C 180 g / L sodium carbonate solution, maintaining a flow rate of 0.2 times the volume of the sodium carbonate solution per hour. The resulting lithium carbonate was dried to obtain high-purity lithium carbonate. The generated sodium itaconate is converted with sulfuric acid and then crystallized to precipitate itaconic acid.

[0057] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing high-purity lithium carbonate using waste lithium batteries, characterized in that: The following steps are involved: S1, mixing waste lithium battery black powder with leaching acid 1, performing selective leaching to obtain lithium-containing leachate and leaching residue; S2, adding impurity remover 1 to the lithium-containing leachate to remove impurities once, to obtain a lithium-containing impurity-removed liquid and impurity-removed slag 1; S3, using impurity remover 2 to deeply remove impurities from the lithium-containing impurity-removed liquid to obtain a lithium precipitation pre-liquid and impurity-removing liquid 1; S4, adding the lithium precipitation pre-liquid dropwise to the sodium carbonate solution to obtain high-purity lithium carbonate and lithium precipitation mother liquor; S5. Recover the leaching acid in the lithium precipitation mother liquor.

2. A method for preparing high-purity lithium carbonate using waste lithium batteries according to claim 1, characterized in that: In step S1, the waste lithium battery black powder is selected from one or more of lithium iron phosphate, ternary lithium, lithium cobalt oxide, lithium iron manganese phosphate, and lithium manganate black powder; and the leaching acid 1 is selected from one or more of organic acid, inorganic acid, and organic acid salt.

3. A method for preparing high-purity lithium carbonate using waste lithium batteries according to claim 2, characterized in that: The inorganic acid is sulfuric acid or hydrochloric acid, the organic acid is itaconic acid, and the organic acid salt is sodium itaconate.

4. A method for preparing high-purity lithium carbonate using waste lithium batteries according to claim 1, characterized in that: In step S1, the sum of the molar concentrations of the leaching acid 1 is 0.2 mol / L-4.0 mol / L; The selective leaching is multi-stage countercurrent leaching, the leaching stages are 1-10, the reaction ratio is 2-50 mL / g, the temperature is 20-80° C., and the time is 2-240 min.

5. A method for preparing high-purity lithium carbonate using waste lithium batteries according to any one of claims 1 to 4, characterized in that: It also includes that when the waste lithium battery black powder is selected from ternary lithium or lithium cobalt oxide, the primary impurity removal in step S2 is not performed.

6. A method for preparing high-purity lithium carbonate using waste lithium batteries according to claim 1, characterized in that: In step S2, the impurity remover 1 is selected from one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, lithium hydroxide, lithium carbonate, ammonia water, and liquid ammonia, and the concentration of the impurity remover 1 is 20-200 g / L.

7. A method for preparing high-purity lithium carbonate using waste lithium batteries according to claim 1, characterized in that: In step S2, the primary impurity removal is: adjusting the pH value of the lithium-containing leachate to 1.50-7.0 using the impurity remover 1 at 20-60°C.

8. A method for preparing high-purity lithium carbonate using waste lithium batteries according to claim 1, characterized in that: In step S3, the impurity remover 2 is selected from TP207 resin, One of CH-93 resin, Haipu HP8 resin, and D860 resin.

9. A method for preparing high-purity lithium carbonate using waste lithium batteries according to claim 1, characterized in that: In step S3, the deep impurity removal is a multi-stage series impurity removal, and the number of impurity removal stages is 2-6.

10. The method for preparing high-purity lithium carbonate from waste lithium batteries according to claim 1, wherein: In step S4, the concentration of the sodium carbonate solution is 180-220 g / L; the dropwise addition method is: at a reaction temperature of 80-98° C., the flow rate of the lithium precipitation pre-liquid is controlled to be 0.1-0.5 times the volume of the sodium carbonate solution per hour.

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