Method for selectively extracting lithium from positive electrode material / black powder of waste lithium ion battery

Abstract

The invention discloses a method for selectively extracting lithium from a positive electrode material / black powder of a waste lithium ion battery. Performing chlorination transformation on the waste lithium ion battery positive electrode material / black powder to obtain chlorination transformation slag; and then, leaching the chlorination transformation slag with water to obtain a lithium chloride solution and lithium extraction slag. And a lithium chloride solution obtained through primary leaching can be used as a leaching solution to circularly leach the chlorination transformation slag, and after Li < + > in the circulating leaching solution is fully enriched, a lithium precipitation reagent is added into the circulating leaching solution, so that the Li < + > is opened in a lithium salt precipitation form. The method has the advantages of low reaction temperature, high reaction efficiency, high valuable metal yield, low production cost and the like, and has a good application prospect.

Description

Technical Field

[0001] The invention relates to a method for selectively extracting lithium from waste lithium-ion battery positive electrode materials / black powder, belonging to the technical field of comprehensive recycling of waste lithium-ion battery electrode materials. Background Art

[0002] In recent years, with the increasing popularity of new energy vehicles and the substantial development of the energy storage industry, the installed capacity of lithium-ion batteries has continued to rise; at the same time, with the increase in years of use, the number of scrapped lithium-ion batteries has also risen sharply.

[0003] Scrapped lithium-ion batteries contain valuable metals such as Li, Ni, Co, Mn, and P, and are a rare urban mine. At the same time, scrapped lithium-ion batteries also contain a large number of hazardous materials, such as lithium hexafluorophosphate, diaphragms, etc.; if not properly handled, they will cause serious environmental pollution. In summary, based on resource recovery and environmental protection, the recycling of scrapped lithium-ion batteries is of great significance.

[0004] The positive electrode material contains a large amount of valuable metals, which is the focus of recycling the positive electrode powder / black powder of waste lithium-ion batteries. The current mainstream recycling methods include wet method, pyrometallurgical-wet method and electrochemical method. The wet method mainly extracts the valuable metals in the active material by acid and alkali leaching. The wet extraction has the advantages of high yield of valuable metals and thorough separation. However, the large amount of wastewater generated by the wet process has always been a major problem that plagues the production of enterprises; at the same time, the wet extraction process often requires the use of expensive reagents such as hydrogen peroxide and sodium persulfate, which are important costs that cannot be ignored in the production process. Pyrometallurgical-wet method combined treatment refers to the activation of active materials by high temperature, which is conducive to the subsequent leaching process. The pyrometallurgical-wet method combined treatment process can reduce the acid and alkali consumption and wastewater generation to a certain extent. However, the pyrometallurgical treatment process has high energy consumption, so the use of this method to treat the active materials of scrapped lithium-ion batteries has obvious disadvantages in terms of cost. In addition, for scrapped lithium iron phosphate batteries, high temperature conditions may cause the destruction of the lithium iron phosphate olivine structure, which is not conducive to the subsequent recovery of iron phosphate. Electrochemical treatment can be divided into electrodialysis and electrolysis. This method is still in the laboratory stage and there are few related industrial reports.

[0005] In summary, existing waste lithium-ion battery recycling technologies generally have problems such as large amount of wastewater and high energy consumption, which seriously restricts the development of the lithium battery recycling industry. In particular, with the decline in lithium prices in recent years, existing lithium battery recycling technologies have been unable to meet the production requirements of enterprises. An economical and efficient waste lithium battery recycling technology is a bottleneck that urgently needs to be broken through in this field. Summary of the invention

[0006] The present invention proposes to use chlorine gas as an oxidizing agent and a chlorinating agent to treat waste lithium-ion battery cathode powder / black powder, and lithium in the waste lithium-ion battery active material can be converted into LiCl at a relatively low temperature or even at room temperature. Then, selective leaching of lithium is achieved through water leaching. At the same time, the current collector aluminum chips basically do not participate in the reaction. The water leaching solution is enriched with Li through cyclic leaching + After that, the corresponding lithium salt product and the solution after lithium precipitation are obtained through a precipitation reaction; the solution after lithium precipitation is evaporated and crystallized to obtain crude sodium chloride, which can be returned for electrolytic preparation of chlorine gas.

[0007] To achieve the above technical objectives, the present invention adopts the following technical solutions:

[0008] (1) Low-temperature chlorination transformation. The waste lithium-ion battery cathode powder / black powder is heated to a set temperature, and then chlorine gas with a certain concentration is introduced into the reactor to obtain a chlorination transformation slag.

[0009] (2) Lithium extraction by water leaching. The chlorination transformation slag obtained in step (1) is leached with pure water, and then the leaching solution and the leaching residue are obtained through liquid-solid separation.

[0010] (3) Lithium precipitation. The leaching solution obtained in step (2) is used to cyclically leach the chlorination transformation slag described in step (1). After the Li + concentration is enriched to a certain extent, a precipitating agent is added to the lithium-rich solution to obtain a lithium salt precipitate and a solution after lithium precipitation.

[0011] (4) Recovery of sodium chloride. The solution after lithium precipitation in step (3) is evaporated and crystallized to obtain crude sodium chloride, which can be used for electrolytic preparation of chlorine gas to achieve the closed-loop circulation of chloride ions.

[0012] Preferably, the waste lithium-ion battery cathode material / black powder in step (1) is one or a combination of waste lithium iron phosphate cathode material / black powder, waste ternary cathode material / black powder, waste lithium cobalt oxide cathode material / black powder, waste lithium manganese oxide cathode material / black powder, and waste lithium manganese iron phosphate cathode material / black powder.

[0013] Preferably, the reaction temperature in step (1) is 0-350 °C, and more preferably 10-100 °C.

[0014] Preferably, the reaction time in step (1) is 5-60 min, and more preferably 10-20 min. It should be noted that the reaction time is closely related to the reactor type. The above reaction time is obtained under static calcination conditions. If fluidized bed calcination is used, the reaction time can be further shortened.

[0015] Preferably, the chlorine gas concentration in step (1) is above 1 vol.%. Considering the problem of intense heat release during the reaction with high-concentration chlorine gas, the chlorine gas concentration can be further preferably 5-40 vol.%.

[0016] Preferably, the amount of chlorine gas introduced in step (1) is 1 to 5 times the theoretical amount required to oxidize Fe in the waste lithium battery active material to Fe 2+ to Fe 3+ in the waste lithium battery active material.

[0017] Preferably, the liquid (ml): solid (g) ratio in the leaching process in step (2) is 2.5:1 to 5:1.

[0018] Preferably, the temperature in the leaching process in step (2) is above 0 °C, and more preferably 15 to 50 °C considering the leaching efficiency.

[0019] Preferably, the time of the leaching process in step (2) is 5 to 60 min, and more preferably 15 to 30 min.

[0020] Preferably, the precipitant in step (3) is a substance that can react with Li + to form a stable lithium salt precipitate. For example, it can be sodium carbonate or sodium phosphate.

[0021] Principle

[0022] Taking the scrapped lithium iron phosphate active material as an example, the process principle of the present invention is described in detail as follows:

[0023] During the reaction process, chlorine gas acts as an oxidizing agent and a chlorinating agent successively. That is, in the reaction process, chlorine gas first oxidizes Fe in lithium iron phosphate to Fe 2+ to Fe 3+ , and at the same time generates highly active in-situ Cl - , which will react rapidly with the deintercalated Li + to form soluble LiCl. During this process, the current collector aluminum foil fragments basically do not participate in the reaction, and selective extraction of lithium can be achieved. In addition, the reaction between lithium iron phosphate and chlorine gas is a strongly exothermic reaction, and the reaction heat can maintain the spontaneous and continuous progress of the reaction.

[0024] Beneficial Effects

[0025] The present invention uses extremely cheap chlorine gas as an oxidizing agent and a reducing agent, and can achieve efficient and selective extraction of lithium in waste lithium battery active materials. It has the advantages of low reaction temperature (below 200 °C), fast reaction rate (less than 30 min), low actual cost (not involving high-cost reagents such as acids, alkalis, hydrogen peroxide, and sodium metabisulfite), high selectivity (the current collector aluminum chips do not participate in the reaction), and small amount of wastewater (recyclable leaching). Specific Embodiments

[0026] The following examples illustrate the essence of the present invention, but the protection scope of the present invention is not limited thereto.

[0027] Example 1

[0028] (1) Place 5 g of the spent lithium iron phosphate battery cathode powder in a customized porcelain boat (both ends cut off), flatten it into a 2-mm thick layer, and then place it in a tube furnace. After that, evacuate the air in the furnace with nitrogen and then introduce chlorine at a rate of 100 mL / min and react at 25 °C for 25 min to obtain a chlorinated transformation residue.

[0029] (2) Immerse the transformation residue obtained in step (1) in water in a beaker and leach it for 30 min under the conditions of a temperature of 50 °C and a liquid-solid ratio of 3:1 to obtain a lithium chloride solution and a water-leached residue.

[0030] After chemical detection and calculation, the main elements in the raw material are Li (4.04%), Fe (31.53%), P (18.9%), Al (3.32%), F (1.12%), and the main phase of Al (1.53%) is LiFePO4. The main phases in the transformation residue after treatment in step (1) are LiCl·H2O and FePO4. During the reaction process, the material temperature increases from 25.19 °C to 201.32 °C within 28 seconds. After treatment in step (2), the leaching rate of Li is 98.78%, the leaching rate of P is 1.53%, and the leaching rates of Fe, Al, and F are less than 0.5%.

[0031] Example 2

[0032] (1) Place 5 g of the spent lithium iron phosphate battery cathode powder in a customized porcelain boat (both ends cut off), flatten it into a 2-mm thick layer, and then place it in a tube furnace. After that, evacuate the air in the furnace with nitrogen and then introduce a nitrogen-chlorine mixed gas (chlorine content 20 vol.%) at a rate of 100 mL / min and react at 300 °C for 20 min to obtain a chlorinated transformation residue.

[0033] (2) Immerse the transformation residue obtained in step (1) in water in a beaker and leach it for 30 min under the conditions of a temperature of 50 °C and a liquid-solid ratio of 3:1 to obtain a lithium chloride solution and a water-leached residue.

[0034] After chemical detection and calculation, the main elements in the raw material are Li (4.04%), Fe (31.53%), P (18.9%), Al (3.32%), F (1.12%), and the main phase of Al (1.53%) is LiFePO4. The main phases in the transformation residue after treatment in step (1) are LiCl·H2O and FePO4. After treatment in step (2), the leaching rate of Li is 98.88%, the leaching rate of P is 1.53%, and the leaching rates of Fe, Al, and F are less than 0.5%

[0035] Example 3

[0036] (1) Place 2 g of spent lithium iron phosphate battery cathode powder in a small custom-made boiling tube (tube inner diameter 8 mm, tube height 300 mm, polyethylene tetrafluoro sand core). Then, after evacuating the air in the tube with nitrogen, introduce a nitrogen-chlorine mixed gas (chlorine content 10 vol.%) at 300 mL / min and react at 25 °C for 15 min to obtain a chlorinated transformation residue.

[0037] (2) Place the transformation residue obtained in step (1) in a beaker and leach it with water. Leach for 30 min under the conditions of a temperature of 50 °C and a liquid-solid ratio of 3:1 to obtain a lithium chloride solution and a water-leached residue.

[0038] Through chemical detection and calculation, the main elements in the raw material are Li (4.04%), Fe (31.53%), P (18.9%), Al (3.32%), F (1.12%), and the main phase of Al (1.53%) is LiFePO4. After being treated in step (1), the main phases in the transformation residue are LiCl·H2O and FePO4. During the reaction process, the material temperature increases from 25.21 °C to 126.89 °C in 20 seconds. After being treated in step (2), the leaching rate of Li is 98.02%, the leaching rate of P is 1.32%, and the leaching rates of Fe, Al, and F are all less than 0.6%.

[0039] Example 4

[0040] (1) Add 0.5 g of catalyst A to 5 g of spent ternary black powder. After mixing evenly, place the material in a custom-made porcelain boat (cut off at both ends), flatten it into a 2-mm thick layer, and then place it in a tube furnace. Then, after evacuating the air in the furnace with nitrogen, introduce a nitrogen-chlorine mixed gas (chlorine content 20 vol.%) at 100 mL / min and react at 150 °C for 40 min to obtain a chlorinated transformation residue.

[0041] (2) Place the transformation residue obtained in step (1) in a beaker and leach it with water. Leach for 30 min under the conditions of a temperature of 50 °C and a liquid-solid ratio of 5:1 to obtain a lithium chloride solution and a water-leached residue.

[0042] Through chemical detection and calculation, the main elements in the raw material are Li (3.01%), Ni (12.82%), Co (10.61), Mn (4.55%), F (0.76%), and Al (0.98%). After being treated in step (1), the main phases in the transformation residue are LiCl·H2O and the composite salts of nickel, cobalt, and manganese. After being treated in step (2), the leaching rate of Li is 98.62%, and the leaching rates of Ni, Co, Mn, Fe, Al, and F are less than 0.5%

[0043] Example 5

[0044] Repeat the step (1) in Example 1 three times. Immerse the transformation slag obtained for the first time in water in a beaker. Leach for 30 min under the conditions of a water immersion temperature of 50 °C and a liquid-solid ratio of 3:1 to obtain a lithium chloride solution and water immersion slag. Use this lithium chloride solution as a leaching agent to leach the transformation slag obtained for the second and third times according to the same parameters to enrich Li in the solution. + After detection and calculation, Li in the obtained Li-enriched solution + has a concentration of 29.35 g / L. Then, add 16 mL of 30% sodium carbonate solution to the above Li-enriched solution. After reacting for 1.5 h, filter, wash with hot water, and dry to obtain Li2CO3 product. After analysis and calculation, the Li + precipitation rate is 86.23%, and the purity of Li2CO3 is 99.71%.

[0045] Example 6

[0046] Immerse the transformation slag obtained in step (2) of Example 1 in water in a beaker. Leach for 30 min under the conditions of a water immersion temperature of 30 °C and a liquid-solid ratio of 3:1 to obtain a lithium chloride solution and water immersion slag. After detection and calculation, the Li + concentration in the leachate is 10.28 g / L. Add 6 mL of 30% sodium phosphate solution to the above lithium-containing solution. After reacting for 1 h, filter, wash with hot water, and dry to obtain Li3PO4 product. After analysis and calculation, the Li + precipitation rate is 94.23%, and the purity of Li3PO4 is 99.62%.

[0047] Comparative Example 1

[0048] Other conditions in Comparative Example 1 are the same as those in Example 1, and the only difference is that the chlorination transformation temperature in Comparative Example 1 is 450 °C.

[0049] After chemical detection and calculation. The main phases in the transformation slag after being treated by step (1) are Li3Fe(PO4)3, AlPO4, and FeOCl. After being treated by step (2), the leaching rate of Li is 28.78%, the leaching rate of Fe is 30.53%, and the leaching rates of P, Al, and F are <0.8%. After being treated by step (3), the content of Al is 5.45%, and the contents of the other components remain unchanged. After being treated by step (4), the F content in the slag is 1.43%.

[0050] Comparative Example 2

[0051] Other conditions in Comparative Example 2 are the same as those in Example 4, and the only difference is that catalyst A is not added in Comparative Example 2.

[0052] After chemical detection and calculation, the main elements in the raw materials are Li (3.01%), Ni (12.82%), Co (10.61), Mn (4.55%), F (0.76%), and Al (0.98%). After the treatment in step (1), the main phases in the transformation slag are LiCl·H2O and the composite salts of nickel, cobalt, and manganese. After the treatment in step (2), the leaching rate of Li is 7.29%, and the leaching rates of Ni, Co, Mn, Fe, Al, and F are less than 0.5%.

Claims

1. A method for selectively extracting lithium from waste lithium-ion battery cathode materials / black powder, characterized by the following steps: (1) Low-temperature chlorination transformation. Heat the waste lithium-ion battery cathode powder / black powder to a set temperature, and then introduce chlorine gas with a certain concentration into the reactor to obtain chlorinated transformation slag. (2) Lithium extraction by water leaching. Leach the chlorinated transformation slag obtained in step (1) with pure water, and then perform liquid-solid separation to obtain leachate and leached residue. (3) Lithium precipitation. The leaching solution obtained in step (2) is used to circularly leach the chlorination conversion slag described in step (1). After the Li + concentration is enriched to a certain extent, a precipitant is added to the lithium-rich solution to obtain a lithium salt precipitate and a solution after lithium precipitation. (4) Recovery of sodium chloride. Evaporate and crystallize the post-lithium precipitation solution in step (3) to obtain crude sodium chloride, which can be used for electrolytic preparation of chlorine gas to achieve a closed-loop cycle of chloride ions.

2. A method for selectively extracting lithium from waste lithium-ion battery cathode materials / black powder according to claim 1, characterized in that: The waste lithium-ion battery cathode materials / black powder described in step (1) are one or a combination of waste lithium iron phosphate cathode materials / black powder, waste ternary cathode materials / black powder, waste lithium cobalt oxide cathode materials / black powder, waste lithium manganate cathode materials / black powder, and waste lithium manganese iron phosphate cathode materials / black powder.

3. A method for selectively extracting lithium from waste lithium-ion battery cathode materials / black powder according to claim 1, characterized in that: The reaction temperature described in step (1) is 0 - 350 °C, and further preferably 10 - 150 °C.

4. A method for selectively extracting lithium from the cathode material / black powder of waste lithium-ion batteries according to claim 1, characterized in that: The reaction time described in step (1) is 5 - 60 min, and further preferably 10 - 20 min. It should be noted that the reaction time is closely related to the type of reactor. The above reaction time is obtained under static calcination conditions. If fluidized bed calcination is used, the reaction time can be further shortened.

5. A method for selectively extracting lithium from waste lithium-ion battery cathode materials / black powder according to claim 1, characterized in that: The chlorine gas concentration described in step (1) is above 1 vol.%, and considering the problem of intense heat release during the reaction with high-concentration chlorine gas, the chlorine gas concentration can be further preferably 5 - 40 vol.%.

6. A method for selectively extracting lithium from the cathode material / black powder of waste lithium-ion batteries according to claim 1, characterized in that: The chlorine gas input amount described in step (1) is 1 to 5 times the theoretical amount for oxidizing Fe in the waste lithium battery active material to Fe 2+ 3+ 3+ 3+ 7. A method for selectively extracting lithium from waste lithium-ion battery cathode materials / black powder according to claim 1, characterized in that: The liquid (mL): solid (g) ratio in the leaching process described in step (2) is 2.5:1 - 5:

1.

8. A method for selectively extracting lithium from waste lithium-ion battery cathode materials / black powder according to claim 1, characterized in that: The leaching process temperature described in step (2) is above 0 °C, and considering the leaching efficiency, it is further preferably 15 - 50 °C.

9. A method for selectively extracting lithium from the cathode material / black powder of waste lithium-ion batteries according to claim 1, characterized in that: The leaching process time described in step (2) is 5 - 60 min, and further preferably 15 - 30 min.

10. A method for selectively extracting lithium from waste lithium-ion battery cathode materials / black powder according to claim 1, characterized in that: The precipitant described in step (3) is a substance that can react with Li + to form a stable lithium salt precipitate. For example, it can be sodium carbonate or sodium phosphate.