Method for preparing modified calcium carbonate from solid waste calcium carbonate residues of waste lithium batteries

Abstract

The invention discloses a method for preparing modified calcium carbonate by using solid waste calcium carbonate residues of waste lithium batteries, which comprises the following steps: mixing calcium carbonate residues with an impurity removal agent, stirring, standing for layering, taking lower-layer slurry, adding a carbonizer and a crystal form inducer, stirring, grinding, adding a modifier, and stirring to obtain modified calcium carbonate; after aging, carrying out solid-liquid separation to obtain a solid phase, and drying the solid phase to obtain the modified calcium carbonate. According to the method, the modified calcium carbonate can be produced at lower cost and can be used in various industries, secondary pollution is avoided in the preparation process, and the method has good social benefits, environmental benefits and economic benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of waste lithium battery recycling, and in particular relates to a method for preparing modified calcium carbonate by utilizing solid waste calcium carbonate residue from waste lithium batteries. Background Art

[0002] Calcium carbonate slag is a large solid waste generated in the process of wet recovery of valuable metals from lithium-ion batteries. It has the characteristics of high humidity, high output, and complex impurities. With the gradual promotion of new energy vehicles in my country, the demand for lithium-ion batteries continues to rise, and the first wave of retirement of power lithium-ion batteries has also arrived. In order to avoid environmental pollution caused by retired lithium-ion batteries, the mainstream disposal method of retired lithium-ion batteries is to use hydrometallurgy to recover valuable metals and then prepare them into battery materials. This method will inevitably produce various low-value industrial waste residues in the process of extracting valuable metals from lithium-ion batteries. These industrial waste residues are produced in large quantities, and their storage will occupy land resources and cause serious air and water and soil pollution. However, the cost and disposal cycle of landfill, incineration, pyrolysis and microbial decomposition are long, and may even cause secondary pollution to the soil.

[0003] At present, because calcium carbonate slag solid waste contains a certain amount of heavy metals and has a high water content, the disposal cost is high and the added value of the finished product is low. Therefore, there is an urgent need for a treatment method for calcium carbonate slag solid waste with low cost and added value for the finished product. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a method for preparing modified calcium carbonate using solid waste calcium carbonate slag from waste lithium batteries, which can produce modified calcium carbonate at a relatively low cost and can be used in a variety of industries. There is no secondary pollution during the preparation process, and it has good social, environmental and economic benefits.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions:

[0006] A method for preparing modified calcium carbonate using solid waste calcium carbonate residue from waste lithium batteries comprises the following steps: mixing the calcium carbonate residue with an impurity remover, stirring and then standing to separate layers, taking the lower layer of slurry, washing, filtering and pulping, adding a carbonizing agent and a crystal form inducing agent, stirring and then grinding, adding a modifier, aging and then performing solid-liquid separation to obtain a solid phase, and drying the solid phase to obtain the modified calcium carbonate.

[0007] Preferably, the impurity remover comprises sulfuric acid solution and tributyl phosphate.

[0008] Preferably, the impurity remover is mixed in a manner of adding a sulfuric acid solution to the calcium carbonate slag, so that the calcium carbonate slag is completely dissolved in the sulfuric acid solution to form a mixed slurry, wherein the mass concentration of the sulfuric acid solution is 25%-40%; and then tributyl phosphate is added, wherein the amount of tributyl phosphate added is 20-40 mm above the liquid surface of the mixed slurry.

[0009] Preferably, the step of standing and stratifying after stirring means stirring at 50-100 r / min for 30-45 min at 60-100° C. and then standing and stratifying, and the standing and stratifying time is 60-240 min.

[0010] During the impurity removal process, impurities such as Si, Na, Mg, Al, and K contained in the calcium carbonate slag are removed; on the one hand, the adverse effects of F and P on the treatment of calcium carbonate can be eliminated, and the formation of insoluble Ca 3 (PO 4 ) 2 , so that it is wrapped on the surface of the reaction product crystal, reducing its carbonation conversion rate, eliminating the influence of F on the morphology of calcium carbonate crystals, and increasing the filtration performance of the product; on the other hand, by removing impurities, especially heavy metals, the whiteness of the product can be greatly improved, and the product quality can be improved.

[0011] Preferably, the slurry after impurity removal is washed with water for 1-3 times and then filtered, and the filter water obtained by filtration is returned for use in preparing the impurity remover.

[0012] Preferably, the filter cake after the filter pressing is pulped to make the material concentration be 20-40%.

[0013] Preferably, the carbonizing agent comprises sodium gluconate solution and aqueous ammonia.

[0014] Preferably, the carbonizing agent is added by first adding sodium gluconate to the lower slurry and mixing, so that the mass concentration of sodium gluconate in the lower slurry is 70%-95%, stirring and filtering to obtain a filter cake, and then putting the filter cake into ammonia water, stirring to form a mixed material and introducing carbon dioxide gas.

[0015] Preferably, the amount of carbon dioxide gas introduced is 40%-80% of the volume of the mixed material, the ventilation speed is 1.2-3.5 m / s, and the mixed material is stirred at a rate of 100-150 r / min for 90-120 min during ventilation.

[0016] Preferably, the crystal form inducing agent is at least one of sodium sulfate, sodium bisulfite, strontium chloride and calcium chloride.

[0017] Preferably, the amount of the crystal form inducing agent added is 1%-3% of the mass of the mixed material.

[0018] Preferably, after adding the crystal form inducing agent, stirring is continued at a rate of 100-150 r / min for 90-120 min.

[0019] By adding sodium gluconate, the Ca 2+ Chelation occurs, making the Ca 2+ The concentration continues to decrease, which promotes the continuous dissolution of calcium salts. 2+ It undergoes a ternary reaction with ammonia water and the introduction of carbon dioxide, and produces needle-shaped calcium carbonate under the induction of a crystal inducer.

[0020] Preferably, the solid content of the material during the grinding is 50%-60%, and the grinding fineness is 2-3 μm.

[0021] Preferably, the grinding medium is alumina balls, the diameter of the alumina balls is 0.5-2 mm, and the material-ball ratio is 1:(3-6).

[0022] The calcium carbonate particles are refined by grinding and the particle surface is activated to change its surface physical and chemical structure and crystal structure. The molecular lattice is displaced, resulting in an increase in internal energy and an increase in particle temperature, thereby dissolving or thermally decomposing, and obtaining an active surface under the action of mechanical force.

[0023] Preferably, the modifier is polydiallyldimethylammonium chloride.

[0024] Preferably, the amount of the modifier added is 2.5%-6% of the mass of the material obtained after grinding.

[0025] Preferably, after adding the modifier, stirring is performed at a rate of 100-150 r / min for 90-120 min and then aging is performed.

[0026] Preferably, the aging time is 120-180 min.

[0027] Preferably, the aged slurry is washed with water 1-3 times and then filtered, and the filter water obtained by the filtration is returned for use as grinding water.

[0028] Preferably, the drying temperature of the modified calcium carbonate is 80-120°C.

[0029] The beneficial effects of the present invention are:

[0030] 1. The raw material is calcium carbonate slag, a large solid waste generated by the treatment of waste lithium batteries. After treatment, the whiteness, oil absorption value and activation of the modified calcium carbonate are greatly improved. Before modification, the calcium carbonate is ground to increase its fineness and surface energy, making its modification effect better. Through the modification, the calcium carbonate particles can produce pre-flocculation in water, thereby showing good filling and filling retention, making it suitable for acidic systems.

[0031] 2. The calcium carbonate slag is treated with impurities removal and carbonization to eliminate impurities in the calcium carbonate slag that affect the formation of calcium carbonate crystal morphology and have adverse effects on modified calcium carbonate. Through the impurity removal process, calcium carbonate with a certain crystal form is converted into other forms, and then the addition of crystal inducers is used to induce the calcium carbonate to grow into needle-like crystals, making calcium carbonate better suitable for specific fields and greatly increasing its added value.

[0032] 3. In the whole process of the present invention, waste water is recycled without generating secondary pollution. Compared with the disposal method of burning quicklime, the modified calcium carbonate obtained by this method greatly reduces energy consumption and has good social, environmental and economic benefits.

[0033] 4. The present invention can be produced in coordination with the quicklime production line, using the CO generated by the quicklime production line 2 Carbonization can further reduce production costs, while reducing greenhouse gas emissions and protecting the environment.

[0034] 5. The method of the present invention aims to solve the disposal problem of calcium carbonate slag in a green and environmentally friendly way, maximize its economic value and environmental value, and turn waste into treasure. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the process of Example 1 of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0037] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0038] The calcium carbonate slag used in the following embodiments is a filter cake, block or agglomerated powdered calcium carbonate slag with a moisture content of ≥32%.

[0039] In the following embodiments, the calcium carbonate slag used, measured by the mass of the calcium carbonate slag dry basis, includes: a calcium content of 76% (calculated as calcium oxide), a sodium content of 5% (calculated as sodium oxide), a sulfur content of 7% (calculated as sulfur dioxide), a magnesium content of 2% (calculated as magnesium oxide), and an aluminum content of 1% (calculated as aluminum oxide).

[0040] Embodiment 1:

[0041] This embodiment provides a method for preparing modified calcium carbonate using solid waste calcium carbonate slag from waste lithium batteries, such as Figure 1 As shown, the specific steps are as follows:

[0042] (1) Mixing calcium carbonate slag with sulfuric acid solution until the calcium carbonate slag is completely dissolved in the sulfuric acid solution, controlling the mass concentration of sulfuric acid in the final slurry to be 30%, adding tributyl phosphate after stirring evenly, and adding it to a thickness of 30 mm above the liquid surface of the mixed slurry, and then stirring at 80° C. at a speed of 100 r / min for 30 minutes, standing for stratification, and the standing time is 120 minutes, and then separating the upper and lower layers, and the lower layer slurry is the calcium carbonate slag after impurities are removed;

[0043] (2) After the impurities are removed, the lower slurry is washed twice and filtered, and the filter press water obtained is returned to step (1) for preparing sulfuric acid solution;

[0044] (3) slurrying the filter cake after filtration, with the slurry concentration being 30%;

[0045] (4) adding sodium gluconate to the slurry to make the mass concentration of sodium gluconate in the slurry reach 90%, stirring at room temperature at a rate of 150 r / min for 180 min, and then filtering by pressure to obtain a filter cake;

[0046] (5) The filter cake after the filter press is placed in 28% ammonia water and stirred to form a mixed material, and then carbon dioxide is introduced at a speed of 2.5 m / s until 75% of the volume of the mixed material is introduced. During the process of introducing carbon dioxide, stirring is continued at a speed of 150 r / min for 120 min;

[0047] (6) adding strontium chloride to the mixture, wherein the mass of the added strontium chloride is 3% of the mass of the mixture, and continuously stirring at a speed of 150 r / min for 100 min, and then filtering to obtain a filter cake;

[0048] (7) feeding the filter cake obtained in step (6) into a grinder equipped with alumina balls with a particle size of 1 mm, adding water to make the solid content of the material 50%, controlling the material-ball ratio to 1:5, and grinding. When 98% of the material fineness reaches a particle size of 2 μm, grinding is stopped and the slurry is transported to a slurry pool;

[0049] (8) adding 5% polydiallyldimethylammonium chloride to the slurry, stirring at a speed of 150 r / min for 120 min, and then aging for 160 min;

[0050] (9) washing the aged slurry twice;

[0051] (10) filtering the washed slurry, and returning the obtained filter press water to step (7) for adjusting the solid content of the material;

[0052] (11) drying the filter cake obtained by pressure filtration to obtain calcium carbonate, the drying temperature being 100° C.;

[0053] (12) The dried calcium carbonate is broken up and packaged to obtain the finished modified calcium carbonate.

[0054] The modified calcium carbonate prepared by the above method has an average particle size of 362nm, an activation degree of 97.2%, a whiteness of 96.1%, and an oil absorption value of 28.4mLDOP / 100gCaCO 3 .

[0055] Embodiment 2:

[0056] This embodiment provides a method for preparing modified calcium carbonate using solid waste calcium carbonate slag from waste lithium batteries, and the specific steps are as follows:

[0057] (1) mixing calcium carbonate slag with sulfuric acid solution until the calcium carbonate slag is completely dissolved in the sulfuric acid solution, controlling the mass concentration of sulfuric acid in the final slurry to be 40%, adding tributyl phosphate after stirring evenly, and adding it to a thickness of 40 mm above the liquid surface of the mixed slurry, and then stirring at 80 r / min for 40 min at 100° C., standing for stratification, and the standing time is 100 min, and then separating the upper and lower layers, and the lower layer slurry is the calcium carbonate slag after impurities are removed;

[0058] (2) After the impurities are removed, the lower slurry is washed three times and filtered, and the filter press water obtained is returned to step (1) for preparing sulfuric acid solution;

[0059] (3) slurrying the filter cake after filtration, with the slurry concentration being 40%;

[0060] (4) adding sodium gluconate after slurrying to make the mass concentration of sodium gluconate in the slurry reach 90%, stirring at a rate of 100 r / min for 150 min at room temperature, and then filtering by pressure to obtain a filter cake;

[0061] (5) placing the filter cake after the filter press into 25% ammonia water and stirring evenly to form a mixed material, and then introducing carbon dioxide at a speed of 1.8 m / s until 60% of the volume of the mixed material is introduced. During the introduction of carbon dioxide, stirring is continued at a speed of 120 r / min for 100 min;

[0062] (6) adding strontium chloride to the mixture, wherein the mass of the added strontium chloride is 3% of the mass of the mixture, and continuously stirring at a speed of 120 r / min for 90 min, and then filtering to obtain a filter cake;

[0063] (7) feeding the filter cake obtained in step (6) into a grinder equipped with 2 mm alumina balls, adding water to make the solid content of the material 55%, controlling the material-ball ratio to 1:5, and grinding. When 98% of the material fineness reaches 2 μm, stop grinding and transfer the slurry to a slurry pool;

[0064] (8) adding 3% polydiallyldimethylammonium chloride to the slurry, stirring at a speed of 120 r / min for 180 min, and then aging for 180 min;

[0065] (9) washing the aged slurry twice;

[0066] (10) filtering the washed slurry, and returning the obtained filter press water to step (7) for adjusting the solid content of the material;

[0067] (11) drying the filter cake obtained by pressure filtration to obtain calcium carbonate, the drying temperature being 100° C.;

[0068] (12) The dried calcium carbonate is broken up and packaged to obtain the finished modified calcium carbonate.

[0069] The modified calcium carbonate obtained by the above method has an average particle size of 348nm, an activation degree of 98.0%, a whiteness of 97.2%, and an oil absorption value of 25.7mLDOP / 100gCaCO 3 .

[0070] Embodiment 3:

[0071] This embodiment provides a method for preparing modified calcium carbonate using solid waste calcium carbonate slag from waste lithium batteries, and the specific steps are as follows:

[0072] (1) mixing calcium carbonate slag with sulfuric acid solution until the calcium carbonate slag is completely dissolved in the sulfuric acid solution, controlling the mass concentration of sulfuric acid in the final slurry to be 25%, adding tributyl phosphate after stirring evenly, and adding it to a thickness of 20 mm above the liquid surface of the mixed slurry, and then stirring at 100° C. at a speed of 90 r / min for 45 minutes, standing for stratification, and standing for 200 minutes, and then separating the upper and lower layers, and the lower layer slurry is the calcium carbonate slag after impurities are removed;

[0073] (2) After the impurities are removed, the lower slurry is washed once and then filtered, and the filter press water obtained is returned to step (1) for preparing sulfuric acid solution;

[0074] (3) slurrying the filter cake after filtration, with the slurry concentration being 20%;

[0075] (4) adding sodium gluconate after slurrying to make the mass concentration of sodium gluconate in the slurry reach 70%, stirring at room temperature at a rate of 100 r / min for 150 min, and then filtering by pressure to obtain a filter cake;

[0076] (5) The filter cake after the filtration was placed in 25% ammonia water and stirred evenly to form a mixed material, and then carbon dioxide was introduced at a speed of 1.8 m / s until 50% of the volume of the mixed material was introduced. During the process of introducing carbon dioxide, stirring was continued at a speed of 130 r / min for 90 min;

[0077] (6) adding strontium chloride and calcium chloride to the mixture, wherein the ratio of strontium chloride to calcium chloride is 1:1, and the mass of the added mixture of strontium chloride and calcium chloride is 2.5% of the mass of the mixture, and stirring at a speed of 120 r / min for 90 min, and then filtering to obtain a filter cake;

[0078] (7) feeding the filter cake obtained in step (6) into a grinder equipped with 2 mm alumina balls, adding water to make the solid content of the material 58%, controlling the material-ball ratio to 1:6, and grinding. When 97% of the material fineness reaches 2 μm, stop grinding and transfer the slurry to a slurry pool;

[0079] (8) adding 3% polydiallyldimethylammonium chloride to the slurry, stirring at a speed of 120 r / min for 90 min, and then aging for 150 min;

[0080] (9) washing the aged slurry once;

[0081] (10) filtering the washed slurry, and returning the obtained filter press water to step (7) for adjusting the solid content of the material;

[0082] (11) drying the filter cake obtained by pressure filtration to obtain calcium carbonate, the drying temperature being 80° C.;

[0083] (12) The dried calcium carbonate is broken up and packaged to obtain the finished modified calcium carbonate.

[0084] The modified calcium carbonate obtained by the above method has an average particle size of 348nm, an activation degree of 95.0%, a whiteness of 94.0%, and an oil absorption value of 22.5mLDOP / 100gCaCO 3 .

[0085] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing modified calcium carbonate using solid waste calcium carbonate slag from waste lithium batteries, characterized in that: The following steps are involved: The calcium carbonate slag is mixed with the impurity remover, stirred and then allowed to stand for stratification, the lower slurry is taken, a carbonizing agent and a crystal inducer are added, stirred and then ground, a modifier is added, and after aging, solid-liquid separation is performed to obtain a solid phase, and the solid phase is dried to obtain modified calcium carbonate.

2. A method for preparing modified calcium carbonate using solid waste calcium carbonate slag from waste lithium batteries according to claim 1, characterized in that: The impurity remover includes sulfuric acid solution and tributyl phosphate.

3. A method for preparing modified calcium carbonate using solid waste calcium carbonate slag from waste lithium batteries according to claim 2, characterized in that: The impurity remover is mixed in a manner of first adding a sulfuric acid solution with a mass concentration of 25%-40% to form a mixed slurry, wherein the amount of the sulfuric acid solution added is 15%-30% of the mass of the calcium carbonate slurry; and then adding tributyl phosphate, wherein the amount of the tributyl phosphate added is 20-40 mm above the liquid surface of the mixed slurry.

4. The method for preparing modified calcium carbonate using solid waste calcium carbonate slag from waste lithium batteries according to claim 1, characterized in that: The carbonizing agent includes sodium gluconate solution and ammonia water.

5. A method for preparing modified calcium carbonate using solid waste calcium carbonate slag from waste lithium batteries according to claim 4, characterized in that: The carbonizing agent is added by first adding sodium gluconate to the lower slurry to mix, so that the mass concentration of sodium gluconate in the lower slurry is 70%-95%, stirring and filtering to obtain a filter cake, and then putting the filter cake into ammonia water, stirring to form a mixed material and introducing carbon dioxide gas.

6. A method for preparing modified calcium carbonate using solid waste calcium carbonate slag from waste lithium batteries according to claim 5, characterized in that: The amount of carbon dioxide gas introduced is 40%-80% of the volume of the mixed material, the ventilation speed is 1.2-3.5m / s, and the mixed material is stirred at a rate of 100-150r / min for 90-120min during ventilation.

7. The method for preparing modified calcium carbonate using solid waste calcium carbonate slag from waste lithium batteries according to claim 1, characterized in that: The crystal inducing agent is at least one of sodium sulfate, sodium bisulfite, strontium chloride and calcium chloride.

8. The method for preparing modified calcium carbonate using solid waste calcium carbonate slag from waste lithium batteries according to claim 1, characterized in that: The solid content of the material during the grinding is 50%-60%, and the grinding fineness is 2-3 μm.

9. The method for preparing modified calcium carbonate using solid waste calcium carbonate slag from waste lithium batteries according to claim 1, characterized in that: The modifier is polydiallyldimethylammonium chloride.

10. The method for preparing modified calcium carbonate using solid waste calcium carbonate slag from waste lithium batteries according to claim 1, characterized in that: The amount of the modifier added is 2.5%-6% of the mass of the material obtained after grinding.

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