A treatment method for carbon-containing waste residue from waste lithium-ion batteries

Abstract

The present invention relates to a method for treating carbon-containing waste residue of waste lithium-ion batteries. The carbon-containing waste residue of waste lithium-ion batteries to be treated is dried, crushed, and screened, and the undersize is taken to obtain fine carbon slag; after mixing the fine carbon slag with a dispersant, water or an acidic aqueous solution is added, and stirring is carried out to obtain a mixed slurry; the mixed slurry is mixed with a foaming agent and a collector, the pH is adjusted, and then flotation is carried out to obtain a flotation material and tailings; after drying the flotation material, it is mixed evenly with concentrated sulfuric acid and a fluoride salt, and roasting is carried out to obtain a roasted material; after washing the roasted material with water, water leaching is carried out, and then solid-liquid separation is carried out to obtain a solid material and a leaching solution; after washing the solid material with water, purified carbon powder is obtained; the purified carbon powder is mixed with water-soluble pyrophosphate, after water leaching, filtration, washing with water, and drying are carried out in sequence, graphite powder with a carbon content of not less than 99 wt% is obtained. The present invention can solve the problem that it is difficult to recover graphite from carbon-containing waste residue in the current treatment process of waste lithium-ion batteries.

Description

Technical Field

[0001] The present invention relates to a method for treating carbon-containing waste residues from waste lithium-ion batteries, belonging to the technical field of resource purification and recovery of industrial hazardous waste. Background Art

[0002] In recent years, the environmental situation has been severe and resources have been gradually exhausted. Facing this global dilemma, it is a major challenge for humanity to focus on developing sustainable new energy and clean energy to replace traditional energy. With the increasingly large global new energy market, the market demand for lithium-ion batteries has been continuously increasing, and the upstream and downstream industries are in short supply. At present, the lifespan of lithium-ion batteries is generally 3 - 5 years, and the retirement wave of lithium-ion batteries has arrived. The current effective recycling rate of waste lithium-ion batteries is less than 5%. The number of retired batteries continues to rise but cannot be effectively utilized, resulting in a large number of waste batteries being stored and piled up, causing serious pollution to the environment and also greatly wasting the high-quality mineral resources (valuable metals, highly graphitized carbon materials, etc.) contained in the waste batteries. Therefore, realizing the reasonable recycling of waste lithium-ion batteries will surely become the future trend and the focus of researchers' attention.

[0003] At present, the focus of waste lithium-ion battery recycling mainly concentrates on the recovery of valuable metal elements in the cathode material, while there are few recycling and utilization methods for the graphite anode material. This is mainly due to the mainstream recycling methods of lithium-ion batteries. The first is the pyrometallurgical process. In this recycling process, carbon mainly serves as a reducing agent and hardly remains. The second method is the hydrometallurgical leaching process. In the previous treatment process, it will go through a mechanical crushing step to prepare a mixed powder of the positive and negative electrodes and then enter the hydrometallurgical process. The residue (i.e., the carbon-containing waste residue from waste lithium-ion batteries described in the present invention) remaining after the leaching and extraction process of valuable metals is a complex mixture mainly composed of graphite, various metals, non-metals, and impurities, resulting in great difficulty in treating the carbon-containing waste residue from waste lithium-ion batteries, low economic benefits, and poor reusability. Therefore, many enterprises adopt methods such as stacking and landfill for treatment, causing serious pollution to the environment. Therefore, for the industry problem of the difficult economic and efficient recycling and reuse of the negative electrode of waste lithium-ion batteries, researchers have conducted a series of experimental explorations.

[0004] Chinese Patent Invention Specification CN110364778A discloses a method for recycling waste lithium-ion battery anode sheets. The separation of metal foils and graphite is achieved by using the dispersion effect of ethanol solution on graphite. Subsequently, graphite reacts with sulfuric acid, and after drying, it is sintered at high temperature to obtain graphite oxide. The obtained graphite oxide is mixed with iron salts in a certain mass ratio and sintered at 500 - 800 °C under a protective atmosphere for 3 - 9 h to prepare an Fe / FeO / C composite material and apply it to the anode of a lithium-ion battery for the second time, achieving a relatively good initial discharge specific capacity and retention rate.

[0005] Chinese Invention Patent Specification CN107887666B discloses a method for recycling the negative electrode material of waste lithium-ion batteries. The manually disassembled negative electrode sheets of waste lithium-ion batteries are mixed with a formic acid or acetic acid solution at a concentration of 1-7 mol / L, and stirred for 50-150 min at 15-55 °C to separate the copper foil and the carbon negative electrode, and copper foil with a purity of 99.9% and carbon powder with a purity of more than 99% can be obtained. The obtained carbon powder is mixed with an organic acid and a reducing agent at 5-20 wt.%, and reacted for 30-60 min under the condition of an ultrasonic power of 0-300 W to obtain purified carbon powder with a purity of 99.9%. Finally, high-purity graphite with a purity of 99.9% is obtained by high-temperature treatment at 2200-3000 °C in an inert and reducing atmosphere.

[0006] Chinese Invention Patent Specification CN113036255A discloses a method and application for preparing a silicon-carbon composite material from the negative electrode of waste lithium-ion batteries. The manually disassembled negative electrode sheets are heat-treated at 200-500 °C for 2-48 h, and the undersize graphite is obtained by sieving. The undersize graphite is stirred and leached with an acid solution, and the graphite material is obtained after filtration and drying. The graphite material is mixed with nano-silicon and asphalt dissolved in kerosene in a ratio of 1:(0.05-0.2):(0.1-1), and stirred until the kerosene is completely volatilized. After drying, the mixed material is carbonized under an inert atmosphere at 600-1500 °C for 5-36 h to obtain a silicon-carbon composite material, which can be used to prepare batteries.

[0007] Chinese Invention Patent Specification CN112216894A discloses a method for recycling the negative electrode of waste lithium-ion batteries to prepare a lithium ion sieve composite material. After the waste lithium-ion batteries are crushed and sieved, a positive and negative electrode mixed powder with a particle size <0.3 mm is obtained. The powder, 1-4 mol / L sulfuric acid, and 25-35 wt% hydrogen peroxide solution are mixed in a mass ratio of 1:1:0.1-1:3:0.5, and filtered after leaching. The obtained filter residue is washed and dried, and made into a slurry. A brown slurry is prepared by adding manganese sulfate, ammonium persulfate, an auxiliary agent, and a lithium hydroxide solution. The brown slurry is hydrothermally reacted at 120-220 °C for 2-24 h. The obtained brown solid is washed and dried, and then calcined in an oxygen-containing atmosphere at 300-600 °C for 0.5-4 h to obtain a lithium ion sieve composite material.

[0008] Patent applications such as CN112142044B previously applied by the applicant also relate to the treatment method of carbon slag from waste lithium-ion batteries. Although good treatment effects can be achieved, they are mainly applicable to the treatment of carbon slag from waste lithium-ion batteries with a high carbon content, no sand-like impurities, and low iron and phosphorus contents. Summary of the Invention

[0009] Aiming at the deficiencies of the prior art, the present invention provides a method for treating carbon-containing waste residue of waste lithium-ion batteries to solve the problem of difficult recovery of graphite in the carbon-containing waste residue.

[0010] To solve the above technical problems, the technical solution of the present invention is as follows:

[0011] A method for treating carbon-containing waste residue from waste lithium-ion batteries, comprising the following steps:

[0012] S1. Dry, crush and screen the carbon-containing waste residue from waste lithium-ion batteries to be treated, take the undersize, and obtain fine carbon slag;

[0013] Among them, in the carbon-containing waste residue from waste lithium-ion batteries to be treated, the carbon content is 50-60 wt%, the volatile content is 2-8 wt%, the ash content is 10-30 wt%, and the total content of river sand and emery is 10-30 wt%; the elemental composition of the ash includes one or more of Si, Ca, Fe, Al, P, S, Ni, Co, Mn, Ti, Zr, B, Ba, Li, Mg, Na, K, Sn, Cu, Sr; generally, the volatile matter is mainly one or more of organic matter, electrolyte, diaphragm and acid remaining from the leaching and extraction process of valuable metals;

[0014] S2. Mix the fine carbon slag with a dispersant in a mass ratio of 1:0.1-3, add water or an acidic aqueous solution, and then stir at 25-85°C for 0.5-4 h to obtain a mixed slurry with a liquid-solid ratio of 8-20:1;

[0015] Among them, the dispersant is one or more of sodium carboxymethyl cellulose (CMC), sodium polyacrylate (PAAS), sodium dodecylbenzenesulfonate (SDBS), sodium dodecylsulfonate (SDS), sodium dodecyl sulfate (SDS), absolute ethanol, industrial alcohol, and preferably absolute ethanol and / or industrial alcohol;

[0016] S3. Mix the mixed slurry with a foaming agent and a collector, adjust the pH value to 0-5, and then perform flotation for 0.5-2 h to obtain flotation material and tailings;

[0017] Among them, the foaming agent is one or more of cresylic acid, 2 # oil, 4 # oil, pine oil, methyl isobutyl carbinol, and the collector is one or more of kerosene, diesel oil, n-dodecane;

[0018] S4. After drying the flotation material, mix it evenly with concentrated sulfuric acid and a fluoride salt in a mass ratio of 100:(80-180):(2-20), and roast at 150-300°C for 1-5 h to obtain a roasted material;

[0019] Among them, the fluoride salt is one or more of sodium fluoride, lithium fluoride, aluminum fluoride, calcium fluoride; preferably, the drying temperature is 40-120°C and the drying time is 4-24 h;

[0020] S5. After washing the calcined material with water, soak it in water at 30 - 90°C for 1 - 12 h, then separate the solid and liquid to obtain a solid material and a leachate;

[0021] Among them, during the water soaking, control the initial liquid - solid mass ratio to be 5 - 30:1;

[0022] S6. After washing the solid material with water, obtain purified carbon powder; optionally, perform multi - stage water washing;

[0023] S7. Mix the purified carbon powder and water - soluble pyrophosphate in a mass ratio of 100:10 - 40, soak it in water at 30 - 80°C for 1 - 12 h, then filter, wash with water, and dry in sequence to obtain graphite powder with a carbon content not less than 99 wt%;

[0024] Among them, during the water soaking, control the initial liquid - solid mass ratio to be 10 - 50:1.

[0025] Further, in S1, the waste lithium - ion battery carbon - containing waste residue to be treated includes one or more of iron - lithium battery carbon slag, cobalt - lithium battery carbon slag, manganese - lithium battery carbon slag, nickel - lithium battery carbon slag, ternary material lithium - battery carbon slag, and lithium iron phosphate battery carbon slag.

[0026] Further, in the waste lithium - ion battery carbon - containing waste residue to be treated, the carbon content is 52 - 58 wt%, the volatile content is 4 - 6 wt%, the ash content is 15 - 25 wt%, and the total content of river sand and emery is 15 - 25 wt%.

[0027] Further, in S1, the particle size of the fine carbon slag is not more than 150 μm.

[0028] Preferably, in S1, the drying temperature is 50 - 180°C, further preferably 60 - 120°C, and the drying time is 4 - 36 h, further preferably 12 - 32 h. Drying first can facilitate subsequent crushing and screening.

[0029] Further, in S2, the acidic aqueous solution contains one or more of H2SO4, HCl, HNO3, and HF, and the concentration of the acid in the acidic aqueous solution is 1 - 5 mol / L, preferably 2 - 4 mol / L.

[0030] Further, in S3, for every 250 - 320 g of fine carbon slag in the mixed slurry, add 0.05 - 0.5 mL of foaming agent and 0.6 - 1.5 mL of collector.

[0031] Further, in S3, flotation is carried out in a flotation machine, where the gas flow rate in the flotation machine is 0.10 - 0.50 L / min, preferably 0.20 - 0.30 L / min, and the stirring speed is 1000 - 2500 rpm, preferably 1500 - 2000 rpm.

[0032] Further, in S3, an acid solution with a concentration of 1 - 5 mol / L is used to adjust the pH value to 0 - 5; wherein, the acid solution contains one or more of H2SO4, HCl, HNO3, and HF.

[0033] Further, in S3, the pH value is adjusted to 1 - 4.

[0034] Further, in S4, the flotation material is uniformly mixed with concentrated sulfuric acid and a fluoride salt according to a mass ratio of 100:(80 - 180):(2 - 20), heated to 150 - 300 °C at a rate of 1 - 10 °C / min for roasting for 1 - 5 h, and then cooled to room temperature at a rate of 1 - 10 °C / min to obtain a roasted material.

[0035] Further, in S4, the concentration of the concentrated sulfuric acid is 70 - 98 wt%, and more preferably 95 - 98 wt%.

[0036] Further, in S5, after washing the roasted material with water, it is leached in water at 40 - 80 °C for 2 - 10 h, and then solid-liquid separation is carried out to obtain a solid material and a leachate.

[0037] Further, in S6, the solid material is washed with deionized water at 20 - 80 °C until the pH value of the washing liquid is 6 - 7 to obtain purified carbon powder.

[0038] Optionally, in S6, after washing the solid material with water, it is dried to obtain purified carbon powder with a fixed carbon content of not less than 96 wt%.

[0039] Further, in S7, the water-soluble pyrophosphate is one or more of sodium pyrophosphate, potassium pyrophosphate, and sodium acid pyrophosphate.

[0040] Further, in S7, after leaching in water at 40 - 70 °C for 2 - 10 h, it is filtered, washed with water, and dried in sequence to obtain graphite powder;

[0041] Among them, during water leaching, the initial liquid-solid mass ratio is controlled to be 15 - 45:1.

[0042] Further, in S7, it is washed with deionized water at 20 - 60 °C until the pH value of the washing liquid is 7. Preferably, it is washed with deionized water at 30 - 40 °C.

[0043] Further, in S7, the purified carbon powder and water-soluble pyrophosphate are mixed at a mass ratio of 100:15-35.

[0044] In view of the complex composition and numerous element types of the waste carbon slag from waste lithium-ion batteries in the present invention (the types of impurity elements can be as high as more than 30, including metals such as Fe, Zn, and Mg that are soluble in sulfuric acid and hydrochloric acid, and elements such as Al, Si, Ti, and P that are difficult to be treated with conventional acids. They are physically and chemically doped or combined in different phase forms, resulting in the difficulty of recycling carbon slag through conventional methods such as single acids and alkalis), the carbon content is low, only 50%-60%, and there are technical problems such as great difficulty in recycling. The present invention provides a method for recycling carbon-containing waste slag from waste lithium-ion batteries by an improved sulfurization roasting-pyrophosphate leaching combined method, which solves the problem of difficult recovery of graphite from carbon-containing waste slag in the current treatment process of waste lithium-ion batteries.

[0045] By using a dispersant in the present invention, the graphite in the carbon slag can be evenly dispersed, avoiding the agglomeration and wrapping of graphite particles around fine sand, and ensuring the flotation effect.

[0046] The carbon-containing waste slag in the present invention contains emery, river sand, diaphragm, etc. Such impurities cannot be removed in subsequent treatments such as sulfurization roasting and water bath leaching. Therefore, under the conditions of acidic flotation, the separation of sand and graphite is achieved by using the density difference between sand and graphite and the hydrophobicity of graphite. At the same time, by controlling the pH value of the system, the reduction of the graphite recovery rate caused by the formation of colloids due to Fe in the slag is avoided. Subsequently, by using improved sulfurization roasting, some metal impurities such as Co, Ni, Fe, Mn, Mg, etc. are converted into soluble sulfates, which are dissolved and separated from graphite during the subsequent water bath leaching process; on the other hand, in the case of adding fluorides, Si can be removed in the form of SiF4. Subsequently, through water washing and water leaching, the formed soluble sulfates can be preferably removed. After that, by continuously adding pyrophosphate for water leaching, the reverse dissolution of insoluble salts such as Ca and the complex removal of metals such as Al, Ti, and Sn can be achieved, further deeply removing impurities from graphite, and then obtaining graphite powder with a purity not lower than 99%.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (1) By jointly treating the carbon-containing waste slag from waste lithium-ion batteries by the modified sulfurization roasting-sodium pyrophosphate leaching method in the present invention, the separation of carbon from various metal, non-metal elements, and impurities is achieved, and the recovered graphite has a purity of 99% and can be directly reused.

[0049] (2) The present invention has strong adaptability to raw materials and has good purification and recycling effects on various carbon-containing waste slags from waste lithium-ion batteries with complex compositions.

[0050] (3) The graphite obtained by the treatment method of the present invention has a complete morphology, and the particle size (about 10 - 20 μm) meets the basic requirements of new energy graphite anodes, and has the feasibility of being used as a new energy anode.

[0051] (4) The process of the present invention is simple and controllable, with low energy consumption and a large amount of recycling and treatment, and has good industrialization prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a process flow chart of a method for treating carbon-containing waste residue from waste lithium-ion batteries of the present invention.

[0053] Figure 2 is the SEM image of the purified graphite of Example 1 of the present invention.

[0054] Figure 3 is the XRD pattern of the purified graphite (Material after processing) and the carbon-containing waste residue (Raw material) from waste lithium-ion batteries of Example 1 of the present invention.

[0055] Figure 4 is the digital photo of the tailings of Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0056] The present invention will be described in detail below in conjunction with embodiments. Unless otherwise specified, the relevant percentages refer to mass percentages.

[0057] Example 1

[0058] In this example, the treatment method of the carbon-containing waste residue from waste lithium-ion batteries includes the following steps:

[0059] (1) Take 300 g of carbon-containing waste residue from waste lithium-ion batteries of a domestic factory. Among them, the carbon content in the carbon-containing waste residue is 55.16 wt%, the volatile content is 4.91 wt%, and the ash content is 19.01 wt% ( Figure 1 Among them, the existence forms of various substances in the carbon-containing waste residue are complex, and some characteristic peaks are masked). Among them, the total content of doped river sand and emery is 20.87 wt%. The main element content (wt%) of the ash: S 6.77, Ca 3.27, Si 2.85, Fe 1.54, Al 1.44, Ni 0.55, Co 0.69, Mn0.33, Na 0.33, Ti 0.40, P 0.23, Mg 0.11, Nb 0.0054, Sn 0.018, Zr 0.069.

[0060] (2) Dry and crush the carbon-containing waste residue, sieve it through a 100-mesh sieve, and obtain 270 g of the material passing through the sieve. Mix the material passing through the sieve with an industrial alcohol dispersant evenly at a mass ratio of 1:0.6, add an acidic aqueous solution containing 1 mol / L H2SO4 for dilution, stir for 1 h at 75 °C, and obtain a mixed slurry with a liquid-solid mass ratio of 12:1; then pour the mixed slurry into a flotation machine. Adjust the air flow rate of the flotation machine to 0.12 L / min, the rotation speed to 1500 rpm, add 0.2 ml of methyl isobutyl carbinol foaming agent and 0.8 ml of dodecane collector, add a 4 mol / L H2SO4 solution to adjust the pH to 2, carry out flotation for 40 min, then filter and dry to obtain flotation material and tailings.

[0061] (3) Mix the flotation material with concentrated H2SO4 with a mass concentration of 98 wt% at a mass ratio of 1:1.2, place it in a graphite crucible, continue to stir evenly by adding sodium fluoride at 15 wt% of the flotation material, put it into a high-temperature furnace, heat it to 260 °C at a rate of 3 °C / min, hold for 3 h, then cool to room temperature at a rate of 3 °C / min and take it out to obtain the material after calcination.

[0062] (4) After washing the material after calcination with deionized water, transfer it to a beaker, adjust the liquid-solid ratio to 10:1, carry out water bath leaching at 50 °C for 6 h, then filter to obtain leaching residues; wash the leaching residues to neutral and then dry to obtain purified carbon powder. Subsequently, add sodium pyrophosphate at 20 wt% of the purified carbon powder, add water to control the liquid-solid mass ratio to 30:1, carry out water bath leaching at 60 °C for 3 h, then filter to obtain a filtrate and filter residues. Wash the filter residues until the pH value of the washing solution is 7, filter and dry, and after testing according to the graphite chemical analysis method (GB / T - 2008), 134 g of purified graphite with a purity of 99.17% can be obtained, and the recovery rate is 89.23%.

[0063] Table 1 is the elemental analysis table (ICP) of the filtrate after leaching with sodium pyrophosphate. As can be seen from the table, after adding sodium pyrophosphate and carrying out water bath leaching, elements such as Nb, Ti, Sn, and Zr in the purified carbon powder are transferred to the liquid phase.

[0064] Table 1 Elemental analysis table of the filtrate after leaching with sodium pyrophosphate (unit: ppm)

[0065] Element B Ba Ca Fe Hf Mg Na Content 0.7 0.3 4.2 5.1 0.6 0.9 71.9 Element Nb S Si Sn Ti W Zr Content 8.8 2.9 1.9 9.6 22.4 0.8 20.1

[0066] Example 2

[0067] In this example, the treatment method for the carbon-containing waste residue of waste lithium-ion batteries includes the following steps:

[0068] (1) Take 300 g of the carbon-containing waste residue of waste lithium-ion batteries described in Example 1.

[0069] (2) Dry and crush the carbon-containing waste residue, sieve it through a 100-mesh sieve to obtain 270 g of undersize material. Mix the undersize material with an anhydrous ethanol dispersant in a mass ratio of 1:0.5, mix evenly, dilute with water, stir for 1 h at 80 °C to obtain a mixed slurry with a liquid-solid mass ratio of 13:1; then pour the mixed slurry into a flotation machine. Adjust the air flow rate of the flotation machine to 0.14 L / min, the rotation speed to 1200 rpm, add 0.2 ml of methyl isobutyl carbinol foaming agent and 1 ml of kerosene collector, add 3 mol / L H2SO4 solution to adjust the pH to 2.5, then carry out flotation for 40 min, filter and dry to obtain flotation material and tailings.

[0070] (3) Mix the flotation material with concentrated H2SO4 with a mass concentration of 98 wt% in a mass ratio of 1:1, place it in a graphite crucible, add sodium fluoride according to 10 wt% of the flotation material and continue to stir evenly, put it into a high-temperature furnace, heat it at a rate of 3 °C / min to 260 °C, hold for 3 h, then cool to room temperature at a rate of 3 °C / min and take it out to obtain the material after calcination.

[0071] (4) Wash the material after calcination with deionized water, transfer it to a beaker, adjust the liquid-solid mass ratio to 15:1, carry out water bath leaching at 60 °C for 6 h, then filter to obtain leaching residue; wash the leaching residue to neutral and then dry to obtain purified carbon powder. Subsequently, add sodium pyrophosphate according to 20 wt% of the purified carbon powder, add water to control the liquid-solid mass ratio to 20:1, carry out water bath leaching at 55 °C for 5 h, wash with water until the pH value of the washing liquid is 7, filter and dry, and after testing according to the graphite chemical analysis method (GB / T - 2008), 130 g of purified graphite with a purity of 99.22% and a recovery rate of 86.61% can be obtained.

[0072] Example 3

[0073] In this example, the treatment method of the carbon-containing waste residue of waste lithium-ion batteries includes the following steps:

[0074] (1) Take 300 g of the carbon-containing waste residue of waste lithium-ion batteries described in Example 1.

[0075] (2) Dry and crush the carbon-containing waste residue, sieve it through a 100-mesh sieve to obtain 270 g of undersize material. Mix the undersize material with an industrial alcohol dispersant in a mass ratio of 1:1, mix evenly, dilute with water, stir for 1 h at 30 °C to obtain a mixed slurry with a liquid-solid mass ratio of 15:1; then pour the mixed slurry into a flotation machine. Adjust the air flow rate of the flotation machine to 0.18 L / min, the rotation speed to 1400 rpm, add 0.2 ml of methyl isobutyl carbinol foaming agent and 0.8 ml of dodecane collector, add 3 mol / L H2SO4 solution to adjust the pH to 2, then carry out flotation for 40 min, filter and dry to obtain flotation material and tailings.

[0076] (3) Mix the flotation material with concentrated H2SO4 with a mass concentration of 98 wt% at a mass ratio of 1:1, place it in a graphite crucible, add sodium fluoride at 10 wt% of the flotation material and continue to stir evenly, put it into a high-temperature furnace, heat it to 250 °C at a rate of 5 °C / min, hold for 4 h, and then cool it to room temperature at a rate of 5 °C / min and take it out to obtain the calcined material.

[0077] (4) After washing the calcined material with deionized water, transfer it to a beaker, adjust the liquid-solid mass ratio to 10:1, leach it in a water bath at 70 °C for 8 h, and then filter to obtain the leached residue; wash the leached residue to neutral and dry it to obtain purified carbon powder. Subsequently, add sodium pyrophosphate at 25 wt% of the purified carbon powder, add water to control the liquid-solid mass ratio to 40:1, leach it in a water bath at 55 °C for 4 h, wash it until the pH value of the washing liquid is 7, filter and dry it, and then test it according to the graphite chemical analysis method (GB / T - 2008) to obtain 137 g of purified graphite with a purity of 99.07% and a recovery rate of 91.13%.

[0078] Example 4

[0079] In this example, the treatment method for waste carbon-containing residues from lithium-ion batteries includes the following steps:

[0080] (1) Take 300 g of the waste carbon-containing residues from lithium-ion batteries described in Example 1.

[0081] (2) Dry, crush the carbon-containing residues, pass through a 100-mesh sieve to obtain 270 g of the undersize material. Mix the undersize material with a sodium dodecyl sulfate dispersant evenly at a mass ratio of 1:0.1, dilute it with water, stir it at 40 °C for 2 h to obtain a mixed slurry with a liquid-solid mass ratio of 14:1; then pour the mixed slurry into a flotation machine. Adjust the air flow rate of the flotation machine to 0.2 L / min, the rotation speed to 1300 rpm, add 0.4 ml of methyl isobutyl carbinol foaming agent and 1.2 ml of kerosene collector, add 2 mol / L H2SO4 solution to adjust the pH to 2, and then carry out flotation for 60 min, filter and dry to obtain the flotation material and tailings.

[0082] (3) Mix the flotation material with concentrated H2SO4 with a mass concentration of 98 wt% at a mass ratio of 1:1.5, place it in a graphite crucible, add a fluoride salt at 15 wt% of the flotation material and continue to stir evenly, put it into a high-temperature furnace, heat it to 270 °C at a rate of 3 °C / min, hold for 2 h, and then cool it to room temperature at a rate of 3 °C / min and take it out to obtain the calcined material.

[0083] (4) After washing the calcined material with deionized water, transfer it to a beaker, adjust the liquid-solid mass ratio to 15:1, perform water bath leaching at 80 °C for 1 h, then filter to obtain the leached residue; wash the leached residue until it is neutral and then dry it to obtain purified carbon powder. Subsequently, add sodium pyrophosphate at 15 wt% of the purified carbon powder, add water to control the liquid-solid mass ratio to 20:1, perform water bath leaching at 60 °C for 4 h, wash with water until the pH value of the washing liquid is 7, filter and dry. After testing according to the graphite chemical analysis method (GB / T - 2008), 136 g of purified graphite with a purity of 99.16% can be obtained, and the recovery rate is 90.55%.

[0084] Example 5

[0085] In this example, the treatment method for waste lithium-ion battery carbon-containing waste residue includes the following steps:

[0086] (1) Take 300 g of the waste lithium-ion battery carbon-containing waste residue described in Example 1.

[0087] (2) Dry and crush the carbon-containing waste residue, pass it through a 100-mesh sieve to obtain 270 g of the undersize material. Mix the undersize material with an industrial alcohol dispersant evenly at a mass ratio of 1:1.5, add water for dilution, then stir at 60 °C for 1 h to obtain a mixed slurry with a liquid-solid mass ratio of 15:1; then pour the mixed slurry into a flotation machine. Adjust the air flow rate of the flotation machine to 0.2 L / min and the rotation speed to 1400 rpm, add 0.2 ml of methyl isobutyl carbinol foaming agent and 1 ml of dodecane collector, add a 4 mol / L H2SO4 solution to adjust the pH to 1, perform flotation for 30 min, then filter and dry to obtain the flotation material and tailings.

[0088] (3) Mix the flotation material with concentrated H2SO4 with a mass concentration of 98 wt% at a mass ratio of 1:1.2, place it in a graphite crucible, add calcium fluoride at 15 wt% of the flotation material and continue to stir evenly, put it into a high-temperature furnace, heat it to 250 °C at a rate of 5 °C / min, hold for 3 h, then cool to room temperature at a rate of 5 °C / min and take it out to obtain the calcined material.

[0089] (4) After washing the calcined material with deionized water, transfer it to a beaker, adjust the liquid-solid mass ratio to 10:1, perform water bath leaching at 80 °C for 8 h, then filter to obtain the leached residue; wash the leached residue until it is neutral and then dry it to obtain purified carbon powder. Subsequently, add sodium pyrophosphate at 20 wt% of the purified carbon powder, add water to control the liquid-solid mass ratio to 30:1, perform water bath leaching at 60 °C for 5 h, wash with water until the pH value of the washing liquid is 7, filter and dry. After testing according to the graphite chemical analysis method (GB / T - 2008), 140 g of purified graphite with a purity of 99.05% can be obtained, and the recovery rate is 93.11%.

[0090] Example 6

[0091] In this embodiment, the method for treating carbon-containing waste residue from waste lithium-ion batteries includes the following steps:

[0092] (1) Take 300 g of the carbon-containing waste residue from waste lithium-ion batteries described in Example 1.

[0093] (2) Dry and crush the carbon-containing waste residue, pass it through a 100-mesh sieve to obtain 270 g of the undersize material. Mix the undersize material evenly with an industrial alcohol dispersant at a mass ratio of 1:1.5, add it to an acidic aqueous solution containing 1 mol / L H2SO4 for dilution, stir for 2 h at 40 °C to obtain a mixed slurry with a liquid-solid mass ratio of 12:1; then pour the mixed slurry into a flotation machine. Adjust the air flow rate of the flotation machine to 0.19 L / min, the rotation speed to 1700 rpm, add 0.1 ml of methyl isobutyl carbinol foaming agent and 1 ml of kerosene collector, add a 4 mol / L H2SO4 solution to adjust the pH to 2.5, then perform flotation for 40 min, filter, and dry to obtain flotation material and tailings.

[0094] (3) Mix the flotation material with concentrated H2SO4 with a mass concentration of 98 wt% at a mass ratio of 1:1.2, place it in a graphite crucible, add sodium fluoride at 8 wt% of the flotation material and continue to stir evenly, put it into a high-temperature furnace, heat it to 250 °C at a rate of 5 °C / min, hold for 2 h, then cool it to room temperature at a rate of 3 °C / min and take it out to obtain the calcined material.

[0095] (4) Wash the calcined material with deionized water, transfer it to a beaker, adjust the liquid-solid mass ratio to 20:1, perform water bath leaching at 60 °C for 12 h, filter to obtain leaching residues; wash the leaching residues to neutral and then dry to obtain purified carbon powder. Subsequently, add sodium pyrophosphate at 25 wt% of the purified carbon powder, add water to control the liquid-solid mass ratio to 35:1, perform water bath leaching at 65 °C for 6 h, wash until the pH value of the washing solution is 7, filter and dry, and after testing according to the graphite chemical analysis method (GB / T - 2008), 138 g of purified graphite with a purity of 99.24% and a recovery rate of 91.96% can be obtained.

[0096] Example 7

[0097] In this embodiment, the method for treating carbon-containing waste residue from waste lithium-ion batteries includes the following steps:

[0098] (1) Take 300 g of waste carbon-containing residue from used lithium-ion batteries of a certain domestic factory. Among them, the carbon content in the carbon-containing residue is 59.81 wt%, the volatile content is 6.32 wt%, and the ash content is 19.21 wt%. The total content of doped river sand and emery is 14.66 wt%. Main element content (wt%) of ash: S 2.68, Co 1.27, Cu 0.08, Ni 1.22, Mn 0.41, Na 0.33, Al 3.39, Fe 3.19, Li 0.21, P 0.93, Ca 3.03, Si 2.21, Mg 0.07.

[0099] (2) Dry, crush the carbon-containing residue, and pass it through a 100-mesh sieve to obtain 290 g of undersize material. Mix the undersize material and sodium carboxymethyl cellulose dispersant evenly at a mass ratio of 1:0.3, add an acidic aqueous solution containing sulfuric acid for dilution, stir for 2 h at 60 °C, and obtain a mixed slurry with a liquid-solid mass ratio of 12:1; then pour the mixed slurry into a flotation machine. Adjust the air flow rate of the flotation machine to 0.19 L / min, the rotation speed to 1700 rpm, add 0.1 ml of methyl isobutyl carbinol foaming agent and 1 ml of kerosene collector, add 4 mol / L H2SO4 solution to adjust to pH = 3, and after flotation for 40 min, filter and dry to obtain flotation material and tailings.

[0100] (3) Mix the flotation material and concentrated H2SO4 with a mass concentration of 98 wt% at a mass ratio of 1:1.2, place it in a graphite crucible, add sodium fluoride at 10 wt% of the flotation material and continue to stir evenly, put it into a high-temperature furnace, heat it to 250 °C at a rate of 5 °C / min and hold for 2 h, then cool it to room temperature at a rate of 3 °C / min and take it out to obtain the material after burning.

[0101] (4) After washing the material after burning with deionized water, transfer it to a beaker, adjust the liquid-solid mass ratio to 20:1, leach it in a water bath at 60 °C for 12 h, then filter to obtain leached residue; wash the leached residue to neutral and dry it to obtain purified carbon powder. Subsequently, add sodium pyrophosphate at 20 wt% of the purified carbon powder, add water to control the liquid-solid mass ratio to 35:1, leach it in a water bath at 60 °C for 6 h, wash it until the pH value of the washing liquid is 7, filter and dry it, and after testing according to the graphite chemical analysis method (GB / T - 2008), 148 g of purified graphite with a purity of 99.91% and a recovery rate of 85.25% can be obtained.

[0102] Example 8

[0103] In this example, the treatment method of waste carbon-containing residue from used lithium-ion batteries includes the following steps:

[0104] (1) Take 300 g of waste carbon-containing residue from lithium-ion batteries of a certain domestic factory. Among them, the carbon content in the carbon-containing residue is 59.08 wt%, the volatile content is 6.47 wt%, and the ash content is 18.18 wt%. The total content of doped river sand and emery is 16.27 wt%. The main element content (wt%) of the ash: S 2.58, Co 1.07, Cu 0.25, Ni 1.31, Mn 0.89, Na 0.56, Al 1.81, Fe 2.6, P 0.41, Ca 3.95, Si 1.08, Mg 0.1, Zn 0.02, Ti 0.21, Zr 0.15.

[0105] (2) Dry and crush the carbon-containing residue, pass it through a 100-mesh sieve to obtain 285 g of undersize material. Mix the undersize material with an anhydrous ethanol dispersant evenly at a mass ratio of 1:1, add an acidic aqueous solution containing sulfuric acid for dilution, stir for 2 h at 60 °C, and obtain a mixed slurry with a liquid-solid mass ratio of 12:1; then pour the mixed slurry into a flotation machine. Adjust the air flow rate of the flotation machine to 0.15 L / min, the rotation speed to 1400 rpm, add 0.1 ml of methyl isobutyl carbinol foaming agent and 1 ml of dodecane collector, add a 2 mol / L H2SO4 solution to adjust the pH to 2, perform flotation for 30 min, then filter and dry to obtain flotation material and tailings.

[0106] (3) Mix the flotation material with concentrated H2SO4 with a mass concentration of 98 wt% at a mass ratio of 1:1, place it in a graphite crucible, add calcium fluoride at 10 wt% of the flotation material and continue to stir evenly, put it into a high-temperature furnace, heat it to 250 °C at a rate of 5 °C / min and hold for 2 h, then cool it to room temperature at a rate of 3 °C / min and take it out to obtain the material after roasting.

[0107] (4) After washing the material after roasting with deionized water, transfer it to a beaker, adjust the liquid-solid mass ratio to 20:1, perform water bath leaching at 60 °C for 12 h, then filter to obtain leaching residue; wash the leaching residue to neutral and dry it to obtain purified carbon powder. Subsequently, add sodium pyrophosphate at 20 wt% of the purified carbon powder, add water to control the liquid-solid mass ratio to 35:1, perform water bath leaching at 60 °C for 6 h, wash until the pH value of the washing liquid is 7, filter and dry, and after testing according to the graphite chemical analysis method (GB / T - 2008), 140 g of purified graphite with a purity of 99.78% and a recovery rate of 82.96% can be obtained.

[0108] Comparative Example 1

[0109] Repeat Example 1, the difference is only that: industrial alcohol is not added.

[0110] Only 125 g of purified graphite with a purity of 94.67% and a recovery rate of 79.46% can be obtained.

[0111] Comparative Example 2

[0112] Repeat Example 4, except that: in step (4), the water bath leaching temperature after adding sodium pyrophosphate is 20°C.

[0113] Only purified graphite with a purity of 97.67% can be obtained.

[0114] Example 7

[0115] Repeat Example 4, except that: in step (4), the water bath leaching temperature after adding sodium pyrophosphate is 40°C, and purified graphite with a purity of 99.01% can be obtained.

[0116] Example 8

[0117] Repeat Example 4, except that: in step (4), the water bath leaching temperature after adding sodium pyrophosphate is 70°C, and purified graphite with a purity of 99.10% can be obtained.

[0118] Comparative Example 3

[0119] Repeat Example 4, except that: in step (4), the water bath leaching temperature after adding sodium pyrophosphate is 90°C, and purified graphite with a purity of 97.24% can be obtained.

[0120] It can be seen that in step (4), when performing water leaching after adding sodium pyrophosphate, the temperature needs to be controlled within a specific range to obtain ideal graphite purity. If the temperature is too low or too high, it may lead to insufficient reaction or decomposition of sodium pyrophosphate, and thus it is difficult to obtain high graphite purity.

[0121] Comparative Example 4

[0122] Repeat Example 5, except that: no sodium pyrophosphate is added. The purity of the finally obtained purified graphite is only 96.93%.

[0123] Comparative Example 5

[0124] Repeat Example 2, except that: in step (4), water bath leaching is not performed, and only the calcined material is washed with water until the calcined material is washed to neutral, then dried to obtain purified carbon powder. The subsequent treatment is the same as that in Example 1, and the purity of the purified carbon powder is 98.11%.

[0125] Comparative Example 6

[0126] Repeat Example 1, except that: in step (4), the water bath leaching temperature of the calcined material is controlled at 20°C, and the purity of the purified graphite is 98.90%.

[0127] Example 9

[0128] Repeat Example 1, except that: in step (4), the water bath leaching temperature of the calcined material is controlled at 30 °C, and the purity of the purified graphite is 98.97%.

[0129] Example 10

[0130] Repeat Example 1, except that: in step (4), the water bath leaching temperature of the calcined material is controlled at 90 °C, and the purity of the purified graphite is 99.19%.

[0131] Comparative Example 7

[0132] Repeat Example 1, except that: in step (4), the water bath leaching temperature of the calcined material is controlled at 95 °C, and the purity of the purified graphite is 99.14%.

[0133] Comparative Example 8

[0134] Repeat Example 1, except that: step (3) is discarded, that is, the flotation material is directly treated as described in step (4), and the purity of the purified graphite obtained is 87.22%.

[0135] Comparative Example 9

[0136] Repeat Example 1, except that: in step (2), after adding 4 mol / L NaOH solution to adjust the pH of the mixed slurry to 12, flotation is carried out to obtain 44 g of flotation material, and the recovery rate of graphite is 22.95%.

[0137] Comparative Example 10

[0138] Repeat Example 1, except that: in step (2), the pH of the mixed slurry is controlled at 7, and after obtaining 144 g of flotation material, flotation is carried out, and the recovery rate of graphite is 71.14%.

[0139] Example 11

[0140] Repeat Example 1, except that: in step (2), after adding 4 mol / L H2SO4 solution to adjust the pH of the mixed slurry to 2, flotation is carried out to obtain 178 g of flotation material, and the recovery rate of graphite is 89.59%.

[0141] The content clarified in the above examples should be understood that these examples are only used to illustrate the present invention more clearly, rather than to limit the scope of the present invention. After reading the present invention, various equivalent modifications made by those skilled in the art fall within the scope defined by the appended claims of this application.

Claims

1. A method for treating carbon-containing waste residue from waste lithium-ion batteries, characterized in that: The steps include: S1. Drying, crushing, and screening the waste lithium-ion battery carbon-containing waste residue to be processed, and taking the sieve underflow to obtain fine carbon residue; The carbon-containing waste residue of waste lithium-ion batteries to be treated has a carbon content of 50-60wt%, a volatile matter content of 2-8wt%, an ash content of 10-30wt%, and a total content of river sand and corundum of 10-30wt%; the elemental composition of the ash includes Fe, and the elemental composition of the ash also includes several of Si, Ca, Al, P, S, Ni, Co, Mn, Ti, Zr, B, Ba, Li, Mg, Na, K, Sn, Cu, and Sr; S2. Mix the fine carbon slag and the dispersant in a mass ratio of 1:0.1-3, add water or an acidic aqueous solution, and stir at 25-85° C. for 0.5-4 h to obtain a mixed slurry with a liquid-to-solid ratio of 8-20:1; Wherein, the dispersant is one or more of sodium lauryl sulfate, anhydrous ethanol, and industrial alcohol; S3, mixing the mixed slurry with a frother and a collector, adjusting the pH value to 0-5 with an acid solution having a concentration of 1-5 mol / L, and flotating for 0.5-2 h to obtain a flotation material and tailings; Wherein, the foaming agent is cresol acid, 2 # Oil, 4 # One or more of oil, pine oil, and methyl isobutyl carbinol; the collector is one or more of kerosene, diesel, and n-dodecane; the acid solution contains one or more of H2SO4, HCl, HNO3, and HF; 0.05-0.5 mL of foaming agent and 0.6-1.5 mL of collector are added to the mixed slurry corresponding to every 250-320 g of fine carbon slag; Flotation is performed in a flotation machine with an air flow rate of 0.10-0.50 L / min and an agitation speed of 1000-2500 rpm; S4, after drying the flotation material, uniformly mix it with concentrated sulfuric acid and fluoride salt in a mass ratio of 100: (80-180): (2-20), and calcine it at 150-300° C. for 1-5 hours to obtain a calcined material; Wherein, the fluoride salt is one or more of sodium fluoride, lithium fluoride, aluminum fluoride, and calcium fluoride; S5. After washing the burned material with water, soaking it in water at 60-90° C. for 1-12 hours, and then separating the solid and the liquid to obtain a solid material and a leachate; During water immersion, the initial liquid-to-solid mass ratio is controlled to be 5-30:1; S6. Washing the solid material with water to obtain purified carbon powder; S7, mixing the purified carbon powder and water-soluble pyrophosphate in a mass ratio of 100:10-40, soaking in water at 40-70° C. for 1-12 hours, filtering, washing, and drying in sequence to obtain graphite powder having a carbon content of not less than 99 wt %; During water immersion, the initial liquid-to-solid mass ratio is controlled to be 10-50:1; and the water-soluble pyrophosphate is sodium pyrophosphate.

2. The processing method according to claim 1, characterized in that In S1, the particle size of the fine carbon slag is not greater than 150 μm.

3. The processing method according to claim 2, characterized in that In S1, the drying temperature is 50-180°C and the drying time is 4-36 h.

4. The processing method according to claim 1, characterized in that In S2, the acidic aqueous solution contains one or more of H2SO4, HCl, HNO3, and HF, and the concentration of the acid in the acidic aqueous solution is 1-5 mol / L.

5. The processing method according to claim 1, characterized in that In S4, the flotation material is uniformly mixed with concentrated sulfuric acid and fluoride salt in a mass ratio of 100: (80-180): (2-20), heated to 150-300°C at a rate of 1-10°C / min, and calcined for 1-5 hours, and then cooled to room temperature at a rate of 1-10°C / min to obtain a calcined material.

6. The processing method according to claim 1, characterized in that In S6, the solid material is washed with deionized water at 20-80°C until the pH value of the washing liquid is 6-7 to obtain purified carbon powder.

7. The processing method according to claim 1, characterized in that In S7, washing is performed with deionized water at 20-60° C. until the pH value of the washing solution reaches 7.

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