Method for selectively extracting lithium from battery powder and application thereof

Abstract

The application provides a method for selectively extracting lithium from battery powder and application thereof, and the method comprises the following steps: mixing battery powder and a roasting aid, and then roasting to obtain a roasting product; wherein the roasting aid comprises sulfate ions; water immersion is performed on the roasting product, and after solid-liquid separation, a water immersion liquid and a water immersion residue are obtained; one-stage acid leaching is performed on the water immersion residue to obtain a one-stage acid leaching liquid and a one-stage acid leaching residue, then two-stage acid leaching is performed on the one-stage acid leaching residue to obtain a two-stage acid leaching liquid and a two-stage acid leaching residue, part of the two-stage acid leaching liquid is returned to step (1) as the roasting aid, and the other part of the two-stage acid leaching liquid is used for the one-stage acid leaching. The application uses the two-stage acid leaching liquid in the recycling process as the roasting aid, avoids the problems of violent mixing reaction and equipment corrosion in the sulfation roasting, simplifies the recycling process, significantly reduces the cost and environmental risk of the recycling process, and improves the metal recovery rate.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery recycling technology, specifically relating to a method for selectively extracting lithium from battery powder and its application. Background Technology

[0002] With the popularization of renewable energy and new energy vehicles, the global market demand for lithium-ion batteries will further increase. However, due to the limited lifespan of lithium-ion batteries, retired lithium-ion batteries containing large amounts of toxic and harmful substances will undoubtedly have adverse effects on the environment and human health in the future. Furthermore, the efficient utilization of lithium resources faces significant challenges due to high mining costs and inconsistent product quality. Retired lithium-ion batteries contain various metal elements required for the lithium battery industry chain; their proper recycling can simultaneously reduce environmental pollution and alleviate resource scarcity. Therefore, it is essential to develop an efficient, low-cost, and environmentally friendly waste lithium-ion battery recycling technology.

[0003] Among the current selective lithium extraction technologies, the pyrometallurgical-hydrometallurgical combination method is the most widely studied and used method. This method generally adopts the method of adding a large amount of calcining agent (such as sulfuric acid, inorganic salts, etc.) to convert the cathode material. This approach can achieve efficient and selective recovery of lithium, but it requires a large amount of additional reagents, which leads to increased recovery costs and increases the costs of storage, transportation and management.

[0004] Therefore, there is an urgent need to develop a low-cost lithium extraction process to reduce the cost of selective lithium extraction. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for selective lithium extraction from battery powder and its application. This invention utilizes the differences in the chemical properties of various metal elements at high temperatures and their varying stability in binding with sulfate ions to achieve selective lithium sulfation, thereby separating lithium from transition metal elements in the battery powder via water leaching. Compared to traditional processes, this method uses a second-stage acid leaching solution in the recycling process as a roasting aid, avoiding the problems of violent mixing reactions and equipment corrosion during sulfation roasting, simplifying the recycling process, significantly reducing the cost and environmental risks of the recycling process, and improving the metal recovery rate.

[0006] To achieve this objective, the present invention employs the following technical solution:

[0007] In a first aspect, the present invention provides a method for selective lithium extraction from battery powder, the method comprising the following steps:

[0008] (1) Mix battery powder and calcination additive, and then calcinate to obtain calcined product;

[0009] The calcination aid includes sulfate ions;

[0010] (2) The roasted product is subjected to water leaching, and after solid-liquid separation, water leachate and water leachate residue are obtained;

[0011] (3) The water leaching residue is subjected to a first-stage acid leaching to obtain a first-stage acid leaching solution and a first-stage acid leaching residue. Then, the first-stage acid leaching residue is subjected to a second-stage acid leaching to obtain a second-stage acid leaching solution and a second-stage acid leaching residue. Part of the second-stage acid leaching solution is returned to step (1) as the roasting aid, and the other part of the second-stage acid leaching solution is used for the first-stage acid leaching.

[0012] This invention utilizes the differences in the chemical properties of various metal elements at high temperatures and their varying stability in binding with sulfate ions to achieve selective sulfation of lithium, thereby separating lithium from transition metal elements in battery powder via water leaching. Compared to traditional processes, this method uses the second-stage acid leaching solution in the recycling process as a roasting aid, avoiding the problems of violent mixing reactions and equipment corrosion during sulfation roasting, simplifying the recycling process, significantly reducing the cost and environmental risks of the recycling process, and improving the metal recovery rate.

[0013] It should be noted that in roasting with only sulfate as a roasting aid, although the problems of heat release and equipment corrosion in sulfation roasting can be completely solved, other metal salts need to be introduced, which increases the separation and purification process of other metals. However, the present invention uses the second-stage acid leaching solution in the recycling process as a roasting aid, without the addition of any additional metals, and there is no significant increase in either the process or the amount of work.

[0014] It should be noted that the water leachate obtained in step (2) enters the subsequent impurity removal and precipitation process to obtain lithium precipitation product, and the acid leachate obtained in step (3) enters the subsequent impurity removal and extraction process to obtain sulfate (including nickel sulfate, cobalt sulfate and manganese sulfate, etc.).

[0015] As a preferred embodiment of the present invention, the calcination aid in step (1) includes sulfate and / or sulfuric acid. For example, the sulfate may be any one or a combination of at least two of nickel sulfate, cobalt sulfate, or manganese sulfate.

[0016] Preferably, the concentration of sulfate ions in the calcination aid described in step (1) is 240-260 g / L, for example, it can be 240 g / L, 245 g / L, 250 g / L, 255 g / L or 260 g / L, etc.

[0017] In this invention, the concentration of sulfate ions is 240-260 g / L, which is beneficial for the selective extraction of lithium.

[0018] Preferably, the battery powder in step (1) is ternary lithium battery powder, and the ternary lithium battery powder includes the following elements by mass content:

[0019]

[0020] In this invention, the mass content of Ni is 25%-34%, for example, it can be 25%, 27.5%, 30%, 32% or 34%, etc.; the mass content of Co is 3%-6%, for example, it can be 3%, 4%, 5% or 6%, etc.; the mass content of Mn is 3%-5%, for example, it can be 3%, 3.5%, 4%, 4.5% or 5%, etc.; the mass content of Li is 4%-6%, for example, it can be 4%, 4.5%, 5%, 5.5% or 6%, etc.; the mass content of C is 30%-50%, for example, it can be 35%, 40%, 45% or 50%, etc.; and the mass content of O is 16%-27%, for example, it can be 16%, 18%, 20%, 22%, 24% or 26%, etc.

[0021] This invention enables the full recycling of ternary battery powder with the above-mentioned mass content in a low-cost and low-environmental-risk manner.

[0022] Preferably, the molar ratio of Li ions to sulfate ions in the battery powder in step (1) is a stoichiometric ratio.

[0023] It should be noted that the stoichiometric ratio refers to the theoretical value obtained by calculating the chemical reaction relationship between Li ions and sulfate ions.

[0024] As a preferred technical solution of the present invention, the roasting temperature in step (1) is 500-600℃, for example, 500℃, 520℃, 540℃, 560℃, 580℃ or 600℃, and the time is 2-4h, for example, 2h, 2.5h, 3h, 3.5h or 4h.

[0025] In this invention, if the roasting temperature is too low, the lithium sulfation transformation will be incomplete, resulting in a low lithium leaching rate and poor selectivity; if the roasting temperature is too high, the sulfate ions will be reduced to sulfides, resulting in a low lithium leaching rate.

[0026] Preferably, the roasted product comprises the following elements by mass content:

[0027]

[0028] In this invention, the mass content of Ni is 19%-25%, for example, it can be 19%, 20%, 21%, 23% or 25%, etc.; the mass content of Co is 3%-6%, for example, it can be 3%, 4%, 5% or 6%, etc.; the mass content of Mn is 3%-5%, for example, it can be 3%, 3.5%, 4%, 4.5% or 5%, etc.; the mass content of Li is 3%-4%, for example, it can be 3%, 3.2%, 3.5%, 3.7% or 4%, etc.; the mass content of C is 20%-45%, for example, it can be 20%, 25%, 30%, 35%, 40% or 45%, etc.; the mass content of O is 18%-30%, for example, it can be 18%, 20%, 22%, 24%, 26% or 28%, etc.; and the mass content of S is 6%-10%, for example, it can be 6%, 7%, 8%, 9% or 10%, etc.

[0029] The present invention obtains the above-mentioned composition by calcining battery powder. It can be seen that the sulfate ions in the calcination aid have reacted with the battery powder and remain in the solid phase.

[0030] As a preferred technical solution of the present invention, the water immersion temperature in step (2) is room temperature.

[0031] It should be noted that the present invention does not limit the specific temperature of room temperature. For example, it can be 25±5℃, or 20℃, 25℃, or 30℃, etc.

[0032] Preferably, the solid-liquid ratio during water immersion in step (2) is 8-12 g / L, for example, it can be 8 g / L, 9 g / L, 10 g / L, 11 g / L or 12 g / L.

[0033] It should be noted that the solid-liquid ratio refers to the ratio of the mass of the calcined product to the volume of water.

[0034] Preferably, the immersion time in water in step (2) is 0.5-1.5h, for example, it can be 0.5h, 1h or 1.5h.

[0035] As a preferred embodiment of the present invention, the aqueous extract in step (2) comprises the following ions according to their mass concentration:

[0036]

[0037] In this invention, the mass concentration of Ni ions is 0-0.05 g / L, for example, it can be 0.01 g / L, 0.02 g / L, 0.03 g / L, 0.04 g / L, or 0.05 g / L, etc.; the mass concentration of Co ions is 0-0.1 g / L, for example, it can be 0.02 g / L, 0.04 g / L, 0.05 g / L, 0.06 g / L, or 0.1 g / L, etc.; the mass concentration of Mn ions is 0-0.1 g / L, for example, it can be 0.02 g / L, 0.04 g / L, 0.05 g / L, 0.06 g / L, or 0.1 g / L, etc.; and the mass concentration of Li ions is 3-4 g / L, for example, it can be 3 g / L, 3.2 g / L, 3.4 g / L, 3.6 g / L, 3.8 g / L, or 4 g / L, etc.

[0038] In this invention, water immersion is used to effectively separate Li from other metal elements.

[0039] As a preferred embodiment of the present invention, the water leaching residue comprises the following elements by mass content:

[0040]

[0041] In this invention, the mass content of Ni is 25%-35%, for example, it can be 25%, 27%, 30%, 32% or 35%, etc.; the mass content of Co is 5%-7%, for example, it can be 5%, 5.5%, 6%, 6.5% or 7%, etc.; the mass content of Mn is 3%-5%, for example, it can be 3%, 3.5%, 4%, 4.5% or 5%, etc.; the mass content of Li is 0-0.5%, for example, it can be 0.1%, 0.2%, 0.3%, 0.4% or 0.5%, etc.; the mass content of C is 35%-50%, for example, it can be 35%, 40%, 45% or 50%, etc.; the mass content of O is 10%-16%, for example, it can be 10%, 11%, 12%, 13%, 14% or 15%, etc.; and the mass content of S is 0-2%, for example, it can be 0.5%, 1%, 1.5% or 2%, etc.

[0042] In this invention, the water leaching residue contains a small amount of Li element, which can be recovered again by acid leaching to prevent the loss of Li.

[0043] As a preferred technical solution of the present invention, the specific steps of the acid leaching in step (3) include:

[0044] The water leaching residue is mixed with a first-stage acid leaching agent, and leaching is performed to obtain the first-stage acid leaching solution and the first-stage acid leaching residue.

[0045] In this invention, the purpose of the first stage of acid leaching is to extract the easily leached components from the water leaching residue and avoid the large amount of acid consumed in the second stage of leaching.

[0046] Preferably, the pH value of the acid leaching solution is 2-3, for example, it can be 2, 2.2, 2.4, 2.6, 2.8 or 3.

[0047] In this invention, by controlling the pH of the leaching solution in a section of acid leaching to 2-3, some easily leached transition metal oxides can be leached out.

[0048] As a preferred technical solution of the present invention, the specific steps of the two-stage acid leaching in step (3) include:

[0049] The first-stage acid leaching residue and the second-stage acid leaching agent are mixed and leached to obtain the second-stage acid leaching solution and the second-stage acid leaching residue.

[0050] In this invention, the purpose of performing two-stage acid leaching is to leach out all the remaining transition metals in the first-stage acid leaching residue.

[0051] Preferably, the pH value of the second-stage acid leaching solution is -1 to 0, for example, it can be -1, -0.5 or 0.

[0052] In this invention, by controlling the pH of the leaching solution in the second-stage acid leaching to -1-0, the remaining transition metals in the first-stage acid leaching residue can be leached out.

[0053] As a preferred technical solution of the present invention, the two-stage acid leaching solution in step (3) includes the following ions according to the mass concentration ratio:

[0054]

[0055] In this invention, the mass concentration of Ni ions is 13-15 g / L, for example, 13 g / L, 13.5 g / L, 14 g / L, 14.5 g / L, or 15 g / L; the mass concentration of Co ions is 10-12 g / L, for example, 10 g / L, 10.5 g / L, 11 g / L, 11.5 g / L, or 12 g / L; the mass concentration of Mn ions is 8-10 g / L, for example, 8 g / L, 8.5 g / L, 9 g / L, 9.5 g / L, or 10 g / L; the mass concentration of Li ions is 0-1 g / L, for example, 0.2 g / L, 0.4 g / L, 0.6 g / L, 0.8 g / L, or 1 g / L; and SO42-... 2- The mass concentration of ions is 240-260 g / L, for example, it can be 240 g / L, 245 g / L, 250 g / L, 255 g / L or 260 g / L, etc.

[0056] The present invention uses a portion of the two-stage acid leaching solution as a roasting aid. Its acidity is much lower than that of sulfuric acid. It only releases heat slightly during mixing, making it easy to produce on a large scale and not requiring high equipment corrosion resistance. Furthermore, the roasting aid does not require the introduction of other metal elements or the addition of other metal separation and purification processes, and there is no significant increase in either the number of processes or the amount of work.

[0057] As a preferred technical solution of the present invention, the method includes the following steps:

[0058] (1) The ternary battery powder and calcination additive are stirred and mixed, and then calcined at 500-600℃ for 2-4 hours to obtain the calcined product. The calcined product includes Ni element with a mass content of 19%-25%, Co element with a mass content of 3%-6%, Mn element with a mass content of 3%-5%, Li element with a mass content of 3%-4%, C element with a mass content of 20%-45%, O element with a mass content of 18%-30%, and S element with a mass content of 6%-10%.

[0059] The calcination aid includes sulfate and sulfuric acid. The molar ratio of Li in the ternary battery powder to sulfate ions in the calcination aid is a stoichiometric ratio. The calcination heating rate is 3-8℃ / min.

[0060] (2) The roasted product is crushed and then subjected to water immersion at room temperature for 0.5-1.5 h. The solid-liquid ratio during water immersion is 8-12 g / L. After filtration, water immersion liquid and water immersion residue are obtained respectively.

[0061] The water leachate contains Ni ions at a concentration of 0-0.05 g / L, Co ions at a concentration of 0-0.1 g / L, Mn ions at a concentration of 0-0.1 g / L, and Li ions at a concentration of 3-4 g / L. The water leachate residue contains Ni element at a mass content of 25-35%, Co element at a mass content of 5-7%, Mn element at a mass content of 3-5%, Li element at a mass content of 0-0.5%, C element at a mass content of 35-50%, O element at a mass content of 10-16%, and S element at a mass content of 0-2%.

[0062] (3) The water leaching residue is washed with water, and then sulfuric acid is used as the first-stage acid leaching agent to perform a first-stage acid leaching on the water-washed water leaching residue for 0.5-1.5 hours to separate a first-stage acid leaching solution with a pH value of 2-3 and a first-stage acid leaching residue. Then, sulfuric acid is used as the second-stage acid leaching agent to perform a second-stage acid leaching on the first-stage acid leaching residue for 0.5-1.5 hours to separate a second-stage acid leaching solution with a pH value of -1-0 and a second-stage acid leaching residue. Part of the second-stage acid leaching solution is recycled to step (1) as a roasting aid, and the other part of the second-stage acid leaching solution is used as a first-stage acid leaching agent for the first-stage acid leaching.

[0063] The second-stage acid leaching solution includes Ni ions at a mass concentration of 13-15 g / L, Co ions at a mass concentration of 10-12 g / L, Mn ions at a mass concentration of 8-10 g / L, Li ions at a mass concentration of 0-1 g / L, and SO4 at a mass concentration of 240-260 g / L. 2- ion.

[0064] The present invention uses only sulfuric acid as a consumable reagent in the entire recycling process, and lithium can be separated from metal elements by water immersion, which effectively simplifies the recycling process of ternary battery powder, reduces the loss of lithium in the process, and improves the metal recovery rate.

[0065] It should be noted that the washing liquid after rinsing can be returned to the water immersion process and used as the water immersion agent required for water immersion.

[0066] It should be noted that, in addition to the components mentioned above in terms of mass content, ternary battery powder also contains a small amount of current collector impurities.

[0067] Secondly, the present invention provides an application of the method described in the first aspect in the field of waste lithium-ion battery recycling.

[0068] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0069] Compared with the prior art, the present invention has the following beneficial effects:

[0070] (1) This invention utilizes the differences in chemical properties of various metal elements at high temperatures and the differences in their stability of binding with sulfate to achieve selective sulfation of lithium, thereby separating lithium from transition metal elements in battery powder by water leaching. Compared with traditional processes, this method uses the second-stage acid leaching solution in the recycling process as a roasting aid. Its acidity is much lower than that of sulfuric acid, and there is only slight exothermic reaction during mixing. This avoids the problems of violent reaction and equipment corrosion during sulfation roasting, significantly reducing the cost and environmental risks of the recycling process, and is easy to mass-produce.

[0071] (2) The method provided by the present invention simplifies the recycling process, reduces lithium loss during the recycling process, and improves the metal recovery rate. Attached Figure Description

[0072] Figure 1 This is a process flow diagram of selective lithium extraction from ternary battery powder provided in Example 1 of the present invention. Detailed Implementation

[0073] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0074] It should be noted that the room temperature below refers to 25℃.

[0075] Example 1

[0076] This embodiment provides a method for selective lithium extraction from ternary lithium battery powder, and its process flow diagram is as follows: Figure 1 As shown, the method includes the following steps:

[0077] (1) The ternary battery powder and calcination additive were mixed in an alumina crucible at a solid-liquid ratio of 1g:1.47mL for 5min to make them evenly mixed into a slurry. Then the crucible containing the slurry was transferred to a muffle furnace for calcination. The temperature was increased to 550℃ at a heating rate of 5℃ / min and held at the temperature for 3h to obtain the calcined product.

[0078] The ternary battery powder comprises 32.94% Ni, 5.49% Co, 3.44% Mn, 5.12% Li, 28.24% C, and 23.61% O by mass. The calcination product comprises 24.15% Ni, 5.15% Co, 3.5% Mn, 3.72% Li, 26.98% C, 26.52% O, and 8.58% S by mass. The calcination aid is sulfuric acid with a sulfate concentration of 240.97 g / L.

[0079] (2) The roasted product is fed into a crusher and crushed into powder. Then the obtained material is transferred to a stirred reaction tank and water-leached for 1 hour at room temperature and a stirring rate of 300 rpm. The solid-liquid ratio during water leaching is 10 g / L. After water leaching, the product is filtered to obtain water leachate and water leachate residue.

[0080] The water leachate contains 0.02 g / L Ni ions, 0.06 g / L Co ions, 0.05 g / L Mn ions, and 3.44 g / L Li ions. The water leachate residue contains 27.55% Ni, 5.71% Co, 3.37% Mn, 0.35% Li, 48.13% C, 12.08% O, and 0.81% S by mass.

[0081] The water leachate then proceeds to subsequent impurity removal and sedimentation processes.

[0082] (3) The water-leached residue is washed three times. The washing liquid after washing is returned to step (2) as a water-leaching agent. The water-leached residue after washing is prepared into a water-leached residue suspension with a solid-liquid ratio of 20 g / L. Then, concentrated sulfuric acid with a mass fraction of 98% is used as a first-stage acid leaching agent to adjust the water-leached residue suspension for a first-stage acid leaching. A first-stage acid leaching solution with a pH value of 2.2 and a first-stage acid leaching residue are separated. Then, the first-stage acid leaching residue is prepared into a first-stage acid leaching residue suspension with a solid-liquid ratio of 20 g / L. Concentrated sulfuric acid with a mass fraction of 98% is used as a second-stage acid leaching agent to adjust the first-stage acid leaching residue suspension for a second-stage acid leaching. A second-stage acid leaching solution with a pH value of -0.12 and a second-stage acid leaching residue are separated. Part of the second-stage acid leaching solution is returned to step (1) as a roasting aid, and the other part of the second-stage acid leaching solution is used as a first-stage acid leaching agent for a first-stage acid leaching.

[0083] The second-stage acid leaching solution includes Ni ions at a mass concentration of 13.14 g / L, Co ions at a mass concentration of 11.48 g / L, Mn ions at a mass concentration of 9.01 g / L, Li ions at a mass concentration of 0.51 g / L, and SO4 at a mass concentration of 240.97 g / L. 2- ion;

[0084] The first stage of acid leaching solution enters the subsequent impurity removal and extraction processes, and the second stage of acid leaching residue is graphite residue.

[0085] Example 2

[0086] This embodiment provides a method for selective lithium extraction from ternary lithium battery powder, the method comprising the following steps:

[0087] (1) The ternary battery powder and calcination additive were mixed in an alumina crucible at a solid-liquid ratio of 1g:1.13mL for 5min to make them evenly mixed into a slurry. Then the crucible containing the slurry was transferred to a muffle furnace for calcination. The temperature was increased to 550℃ at a heating rate of 5℃ / min and kept at a constant temperature for 3h to obtain the calcined product.

[0088] The ternary battery powder comprises 25.02% Ni, 3.65% Co, 3.2% Mn, 4.11% Li, 44.07% C, and 18.95% O by mass. The calcination product comprises 22.42% Ni, 4.05% Co, 3.01% Mn, 4.06% Li, 27.76% C, 27.14% O, and 9.36% S by mass. The calcination aid is sulfuric acid with a sulfate concentration of 252 g / L.

[0089] (2) The roasted product is fed into a crusher and crushed into powder. Then the obtained material is transferred to a stirred reaction tank and water-leached for 1 hour at room temperature and a stirring rate of 300 rpm. The solid-liquid ratio during water leaching is 10 g / L. After water leaching, the product is filtered to obtain water leachate and water leachate residue.

[0090] The water leachate contains 0.01 g / L Ni ions, 0.01 g / L Co ions, 0.05 g / L Mn ions, and 3.78 g / L Li ions. The water leachate residue contains 32.39% Ni ions, 5.89% Co ions, 4.17% Mn ions, 0.44% Li ions, 39.53% C ions, 14.15% O ions, and 1.02% S ions by mass.

[0091] The water leachate then proceeds to subsequent impurity removal and sedimentation processes.

[0092] (3) The water-leached residue is washed three times. The washing liquid after washing is returned to step (2) as a water-leaching agent. The water-leached residue after washing is prepared into a water-leached residue suspension with a solid-liquid ratio of 20 g / L. Then, concentrated sulfuric acid with a mass fraction of 98% is used as a first-stage acid leaching agent to adjust the water-leached residue suspension for a first-stage acid leaching. A first-stage acid leaching solution with a pH value of 2.0 and a first-stage acid leaching residue are separated. Then, the first-stage acid leaching residue is prepared into a first-stage acid leaching residue suspension with a solid-liquid ratio of 20 g / L. Concentrated sulfuric acid with a mass fraction of 98% is used as a second-stage acid leaching agent to adjust the first-stage acid leaching residue suspension for a second-stage acid leaching. A second-stage acid leaching solution with a pH value of -0.54 and a second-stage acid leaching residue are separated. Part of the second-stage acid leaching solution is returned to step (1) as a roasting aid, and the other part of the second-stage acid leaching solution is used as a first-stage acid leaching agent for a first-stage acid leaching.

[0093] The second-stage acid leaching solution includes Ni ions at a mass concentration of 14.51 g / L, Co ions at a mass concentration of 10.66 g / L, Mn ions at a mass concentration of 8.58 g / L, Li ions at a mass concentration of 0.35 g / L, and SO4 at a mass concentration of 252 g / L. 2- ion;

[0094] The first stage of acid leaching solution enters the subsequent impurity removal and extraction processes, and the second stage of acid leaching residue is graphite residue.

[0095] Example 3

[0096] This embodiment provides a method for selective lithium extraction from ternary lithium battery powder, the method comprising the following steps:

[0097] (1) The ternary battery powder and calcination additive were mixed in an alumina crucible at a solid-liquid ratio of 1g:1.27mL for 5min to make them evenly mixed into a slurry. Then the crucible containing the slurry was transferred to a muffle furnace for calcination. The temperature was increased to 550℃ at a heating rate of 5℃ / min and kept at a constant temperature for 3h to obtain the calcined product.

[0098] The ternary battery powder comprises 28.69% Ni, 4.72% Co, 3.35% Mn, 4.58% Li, 35.69% C, and 21.61% O by mass. The calcination product comprises 23.18% Ni, 4.77% Co, 3.30% Mn, 3.91% Li, 27.68% C, 26.95% O, and 9.02% S by mass. The calcination aid is sulfuric acid with a sulfate concentration of 248.43 g / L.

[0099] (2) The roasted product is fed into a crusher and crushed into powder. Then the obtained material is transferred to a stirred reaction tank and water-leached for 1 hour at room temperature and a stirring rate of 300 rpm. The solid-liquid ratio during water leaching is 10 g / L. After water leaching, the product is filtered to obtain water leachate and water leachate residue.

[0100] The water leachate contains 0.01 g / L Ni ions, 0.02 g / L Co ions, 0.06 g / L Mn ions, and 3.56 g / L Li ions. The water leachate residue contains 29.53% Ni ions, 5.77% Co ions, 3.85% Mn ions, 0.41% Li ions, 45.13% C ions, 13.07% O ions, and 0.95% S ions by mass.

[0101] The water leachate then proceeds to subsequent impurity removal and sedimentation processes.

[0102] (3) The water-leached residue is washed three times. The washing liquid after washing is returned to step (2) as a water-leaching agent. The water-leached residue after washing is prepared into a water-leached residue suspension with a solid-liquid ratio of 20 g / L. Then, concentrated sulfuric acid with a mass fraction of 98% is used as a first-stage acid leaching agent to adjust the water-leached residue suspension for a first-stage acid leaching. A first-stage acid leaching solution with a pH value of 2.4 and a first-stage acid leaching residue are separated. Then, the first-stage acid leaching residue is prepared into a first-stage acid leaching residue suspension with a solid-liquid ratio of 20 g / L. Concentrated sulfuric acid with a mass fraction of 98% is used as a second-stage acid leaching agent to adjust the first-stage acid leaching residue suspension for a second-stage acid leaching. A second-stage acid leaching solution with a pH value of -0.46 and a second-stage acid leaching residue are separated. Part of the second-stage acid leaching solution is returned to step (1) as a roasting aid, and the other part of the second-stage acid leaching solution is used as a first-stage acid leaching agent for a first-stage acid leaching.

[0103] The second-stage acid leaching solution includes Ni ions at a mass concentration of 14.06 g / L, Co ions at a mass concentration of 11.02 g / L, Mn ions at a mass concentration of 8.73 g / L, Li ions at a mass concentration of 0.43 g / L, and SO4 at a mass concentration of 248.43 g / L. 2- ion;

[0104] The first stage of acid leaching solution enters the subsequent impurity removal and extraction processes, and the second stage of acid leaching residue is graphite residue.

[0105] Example 4

[0106] The difference between this embodiment and Embodiment 1 is that the sulfuric acid in step (1) is replaced with nickel sulfate.

[0107] The remaining methods and parameters are consistent with those in Example 1.

[0108] Example 5

[0109] The difference between this embodiment and Embodiment 1 is that the concentration of sulfate in step (1) is 156 g / L.

[0110] The remaining methods and parameters are consistent with those in Example 1.

[0111] Example 6

[0112] The difference between this embodiment and Embodiment 1 is that the concentration of sulfuric acid in step (1) is 337 g / L.

[0113] The remaining methods and parameters are consistent with those in Example 1.

[0114] Example 7

[0115] The difference between this embodiment and Embodiment 1 is that the pH value of a section of the acid leaching solution is 1.

[0116] The remaining methods and parameters are consistent with those in Example 1.

[0117] Example 8

[0118] The difference between this embodiment and Embodiment 1 is that the pH value of a section of the acid leaching solution is 5.

[0119] The remaining methods and parameters are consistent with those in Example 1.

[0120] Example 9

[0121] The difference between this embodiment and Embodiment 1 is that the pH value of the second-stage acid leaching solution is -2.

[0122] The remaining methods and parameters are consistent with those in Example 1.

[0123] Example 10

[0124] The difference between this embodiment and Embodiment 1 is that the pH value of the second-stage acid leaching solution is 1.

[0125] The remaining methods and parameters are consistent with those in Example 1.

[0126] Comparative Example 1

[0127] The difference between this comparative example and Example 1 is that no acid leaching is performed.

[0128] The remaining methods and parameters are consistent with those in Example 1.

[0129] Comparative Example 2

[0130] The difference between this comparative example and Example 1 is that the second-stage acid leaching solution obtained in step (3) is not refluxed and used as a roasting aid in step (1).

[0131] The remaining methods and parameters are consistent with those in Example 1.

[0132] Performance testing

[0133] The lithium recovery rate of the selective lithium extraction in the above embodiments and comparative examples was tested using inductively coupled plasma (ICP) method.

[0134] The test results are shown in Table 1.

[0135] Table 1

[0136]

[0137]

[0138] analyze:

[0139] As can be seen from the above embodiments and Table 1, the present invention uses the second-stage acid leaching solution in the recycling process as a roasting aid, which avoids the problems of violent mixing reaction and equipment corrosion in sulfation roasting, simplifies the recycling process, significantly reduces the cost and environmental risks of the recycling process, and improves the lithium recovery rate.

[0140] As can be seen from Examples 1 and 5-6, if the concentration of sulfate in step (1) is too low, the amount of sulfate in sulfuric acid is insufficient to completely convert lithium into lithium sulfate, resulting in a low lithium leaching rate; if the concentration of sulfate in step (1) is too high, the excess sulfate will combine with nickel, cobalt and manganese, and leach out at the same time as lithium during water leaching, resulting in a decrease in the selectivity of lithium leaching.

[0141] As can be seen from Examples 1 and 7-8, if the pH value of the first-stage acid leaching solution is too low, the metal concentration in the second-stage acid leaching solution will be low and the sulfuric acid concentration will be high, which will lead to severe exothermic reaction and corrosion risk during reflux mixing and roasting; if the pH value of the first-stage acid leaching solution is too high, the acid consumption in the second-stage acid leaching will be too high, increasing the cost.

[0142] As can be seen from Examples 1 and 9-10, if the pH value of the second-stage acid leaching solution is too low, its sulfuric acid content will be high, which will cause severe exothermic reaction and corrosion during reflux roasting; if the pH value of the second-stage acid leaching solution is too high, its sulfate concentration will be too low, which will be difficult to meet the sulfate dosage requirements during reflux mixed roasting.

[0143] As can be seen from Example 1 and Comparative Example 1, if the first stage of acid leaching is not performed, the acid consumption of the second stage of acid leaching will be too high, increasing the cost.

[0144] As can be seen from Example 1 and Comparative Example 2, if the second-stage acid leaching solution obtained in step (3) is not refluxed as a calcination aid in step (1), the lithium in the battery powder cannot be converted into easily water-soluble lithium, resulting in a significant reduction in the lithium leaching rate.

[0145] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for selectively extracting lithium from battery powder, characterized in that, The method includes the following steps: (1) Mix battery powder and calcination aid, and then calcinate to obtain calcined product; The calcination aid includes sulfate ions; (2) The roasted product is subjected to water leaching, and after solid-liquid separation, water leachate and water leachate residue are obtained; (3) The water leaching residue is subjected to a first-stage acid leaching to obtain a first-stage acid leaching solution and a first-stage acid leaching residue. Then, the first-stage acid leaching residue is subjected to a second-stage acid leaching to obtain a second-stage acid leaching solution and a second-stage acid leaching residue. Part of the second-stage acid leaching solution is returned to step (1) as the roasting aid, and the other part of the second-stage acid leaching solution is used for the first-stage acid leaching.

2. The method according to claim 1, characterized in that, The concentration of sulfate ions in the calcination aid described in step (1) is 240-260 g / L.

3. The method according to claim 1, characterized in that, The battery powder mentioned in step (1) is ternary lithium battery powder, and the ternary lithium battery powder includes the following elements by mass content: Ni element 25%-34%; Co element 3%-6%; Mn element 3%-5%; Li element 4%-6%; C content: 30%-50%; O content is 16%-27%.

4. The method according to claim 1, characterized in that, The roasting temperature in step (1) is 500-600℃ and the time is 2-4h.

5. The method according to claim 3, characterized in that, The roasting product includes the following elements by mass content: Ni element 19%-25%; Co element 3%-6%; Mn element 3%-5%; Li element 3%-4%; C element: 20%-45%; O element 18%-30%; S element 6%-10%.

6. The method according to claim 3, characterized in that, The aqueous leachate in step (2) includes the following ions by mass concentration: Ni ions 0-0.05 g / L; Co ions 0-0.1 g / L; Mn ions 0-0.1 g / L; Li ion concentration: 3-4 g / L.

7. The method according to claim 6, characterized in that, The water-leached residue includes the following elements by mass content: Ni element 25%-35%; Co element 5%-7%; Mn element 3%-5%; Li element 0-0.5%; C content: 35%-50%; O element 10%-16%; S element 0-2%.

8. The method according to claim 1, characterized in that, The specific steps of the acid leaching process described in step (3) include: The water leaching residue is mixed with a first-stage acid leaching agent, and leaching is performed to obtain the first-stage acid leaching solution and the first-stage acid leaching residue.

9. The method according to claim 8, characterized in that, The pH value of the acid leaching solution is 2-3.

10. The method according to claim 1, characterized in that, The specific steps of the two-stage acid leaching in step (3) include: The first-stage acid leaching residue and the second-stage acid leaching agent are mixed and leached to obtain the second-stage acid leaching solution and the second-stage acid leaching residue.

11. The method according to claim 10, characterized in that, The pH value of the second-stage acid leaching solution is -1 to 0.

12. The method according to claim 10, characterized in that, The second-stage acid leaching solution in step (3) includes the following ions in a mass concentration ratio: Ni ions 13-15 g / L; Co ions 10-12 g / L; Mn ions 8-10 g / L; Li ions 0-1 g / L; SO4 2- Ions 240-260 g / L.

13. The method according to claim 1, characterized in that, The method includes the following steps: (1) The ternary battery powder and calcination additive are stirred and mixed, and then calcined at 500-600℃ for 2-4 hours to obtain the calcined product. The calcined product includes Ni element with a mass content of 19%-25%, Co element with a mass content of 3%-6%, Mn element with a mass content of 3%-5%, Li element with a mass content of 3%-4%, C element with a mass content of 20%-45%, O element with a mass content of 18%-30%, and S element with a mass content of 6%-10%. The calcination aid includes sulfate and sulfuric acid. The molar ratio of Li in the ternary battery powder to sulfate ions in the calcination aid is a stoichiometric ratio. The calcination heating rate is 3-8℃ / min. (2) The roasted product is crushed and then water-leached at room temperature for 0.5-1.5h. The solid-liquid ratio during water leaching is 8-12g / L. After filtration, water leachate and water leachate residue are obtained respectively. The water leachate contains Ni ions at a concentration of 0-0.05 g / L, Co ions at a concentration of 0-0.1 g / L, Mn ions at a concentration of 0-0.1 g / L, and Li ions at a concentration of 3-4 g / L. The water leachate residue contains Ni element at a mass content of 25-35%, Co element at a mass content of 5-7%, Mn element at a mass content of 3-5%, Li element at a mass content of 0-0.5%, C element at a mass content of 35-50%, O element at a mass content of 10-16%, and S element at a mass content of 0-2%. (3) The water leaching residue is washed with water, and then sulfuric acid is used as the first-stage acid leaching agent to perform a first-stage acid leaching on the water-washed water leaching residue for 0.5-1.5h to separate a first-stage acid leaching solution with a pH value of 2-3 and a first-stage acid leaching residue. Then sulfuric acid is used as the second-stage acid leaching agent to perform a second-stage acid leaching on the first-stage acid leaching residue for 0.5-1.5h to separate a second-stage acid leaching solution with a pH value of -1-0 and a second-stage acid leaching residue. Part of the second-stage acid leaching solution is returned to step (1) as a roasting aid, and the other part of the second-stage acid leaching solution is used as a first-stage acid leaching agent for the first-stage acid leaching. The second-stage acid leaching solution includes Ni ions at a mass concentration of 13-15 g / L, Co ions at a mass concentration of 10-12 g / L, Mn ions at a mass concentration of 8-10 g / L, Li ions at a mass concentration of 0-1 g / L, and SO4 at a mass concentration of 240-260 g / L. 2- ion.

14. The application of the method as described in any one of claims 1-13 in the field of waste lithium-ion battery recycling.

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