Method for selectively extracting lithium from waste lithium ion battery positive electrode material

Abstract

The invention belongs to the technical field of battery material resource recycling, and mainly relates to a method for selectively extracting lithium from a positive electrode material of a waste lithium ion battery. The method specifically comprises the following steps: uniformly mixing waste lithium ion battery positive electrode material powder with concentrated hydrochloric acid, and roasting to obtain a roasted product; water vapor is introduced in the roasting process; carrying out water leaching on the roasted product, and filtering to obtain a lithium-rich leaching solution and leaching residues; and concentrating the lithium-rich leachate, adding alkali, aging, filtering to obtain filtrate, adding sodium carbonate into the filtrate, and carrying out post-treatment to obtain lithium carbonate. The method is high in lithium element recovery rate, high in lithium carbonate product purity, good in separation effect, low in chlorinating agent price, wide in source, free of impurity metal element residues, simple in process and low in cost.

Description

Technical Field

[0001] The invention belongs to the technical field of battery material resource recycling, and mainly relates to a method for selectively extracting lithium from waste lithium-ion battery positive electrode materials. Background Art

[0002] In recent years, with the maturity of high-energy-density lithium-ion batteries and policy guidance, the global new energy vehicle market has grown rapidly, further increasing the scale of lithium-ion battery retirement, and the problem of recycling waste lithium-ion batteries has become increasingly serious.

[0003] At present, the lithium required for the production of lithium-ion batteries is mainly extracted from salt lake brine and high-grade lithium ore. Although salt lake brine has abundant reserves, lithium extraction requires a large amount of brine resources and has a long production cycle. The lithium content in lithium ores such as lepidolite and spodumene is 3.84wt% and 3.73wt%, respectively. Extracting lithium from them has a great impact on the environment, and mining and processing consume a lot of energy. Compared with salt lake brine and lithium ore, the lithium content in waste lithium-ion battery positive electrode materials is about 5-7wt%, and the extraction energy consumption and pollution are far less than the above two sources. Therefore, it is of great significance to extract lithium from waste lithium-ion batteries. Whether from the perspective of environmental protection or resource conservation, the recycling of waste lithium-ion batteries is very necessary and urgent.

[0004] At present, the recycling methods of waste lithium-ion battery positive electrode materials are mainly pyrometallurgical process and wet process. The pyrometallurgical process has a short process and a simple process, but it has problems such as high energy consumption, large air pollution and low lithium recovery rate; the wet process also has problems such as long process, large water consumption and low lithium recovery rate. In recent years, a chlorination roasting method has been proposed: for example, the positive electrode material is mixed with a carbonaceous reducing agent and a chlorinating agent for oxygen-free roasting, and then the roasting product is stirred and filtered to obtain a filtrate, and the filtrate is post-treated to obtain lithium carbonate. This method uses metal chloride as a chlorinating agent, which may introduce metal impurities and make subsequent transition metal recovery and separation difficult; for example, waste lithium battery slag is mixed with metal chloride and chlorinated and roasted at high temperature, and the oxidized lithium in the filter residue is converted into lithium chloride with a lower melting and boiling point, so that the lithium evaporates in the form of lithium chloride to achieve the purpose of selective lithium extraction. This method requires a high roasting temperature and high energy consumption. Therefore, it is necessary to adopt an effective selective lithium extraction method to achieve further expansion of economic benefits. Summary of the invention

[0005] In order to overcome the shortcomings of traditional lithium recovery methods in lithium battery positive electrode materials, the present invention provides a method for selectively extracting lithium from waste lithium-ion battery positive electrode materials, the purpose of which is to achieve efficient conversion of lithium in waste positive electrode materials by adding concentrated hydrochloric acid and passing water vapor for roasting, lithium is converted into soluble lithium salts, transition metals are converted into corresponding oxides, and selective lithium extraction is achieved through water leaching. The method is simple to operate, low in cost, high in lithium recovery rate, and good in separation effect.

[0006] To achieve the above-mentioned object of the invention, the present invention provides a method for selectively extracting lithium from waste lithium-ion battery positive electrode materials, the method comprising the following steps:

[0007] S1. Mixing the waste lithium-ion battery positive electrode material powder and concentrated hydrochloric acid uniformly and then roasting to obtain a roasted product; introducing water vapor during the roasting process;

[0008] S2, leaching the roasted product in water, and filtering to obtain lithium-rich leaching solution and leaching residue;

[0009] S3, concentrating the lithium-rich leachate, adding alkali, aging, and filtering to obtain a filtrate, and then adding sodium carbonate to the filtrate for post-treatment to obtain lithium carbonate.

[0010] In an optional embodiment, before step S1, the waste lithium-ion battery powder is sieved and then dried at 50 to 70° C. for 20 to 30 hours.

[0011] In an optional embodiment, during the roasting process of step S1, the water vapor is introduced at a flow rate of 10 to 200 ml / min.

[0012] In an optional embodiment, the calcination process is: heating to 300-750° C. at a rate of 3-20° C. / min, and then keeping the temperature for 0.5-2.0 h.

[0013] In an optional embodiment, the molar ratio of lithium in the waste lithium-ion battery positive electrode material powder to chlorine in concentrated hydrochloric acid is 1:10 to 3.0.

[0014] In an optional embodiment, during the water immersion process in step S2, the solid-liquid ratio of the roasted product to water is 50-250 g / L, and the water immersion process is stirred at a speed of 100-800 rpm for 0.5-1.0 h.

[0015] In an optional embodiment, in step S3, the concentration specifically includes: evaporating and concentrating the lithium-rich leachate at a temperature of 80-95° C. to a lithium mass concentration of ≥10 g / L.

[0016] In an optional embodiment, in the step S3, alkali is added until the pH value of the lithium-rich concentrated solution is 10-12, the alkali is one or more of sodium hydroxide, potassium hydroxide or lithium hydroxide, and the aging time is 2-4 hours.

[0017] In an optional embodiment, the molar ratio of lithium to sodium carbonate in the lithium-rich leachate is 1:0.60-0.75.

[0018] In an optional embodiment, the post-treatment process includes evaporation crystallization and washing crystals. The temperature of the evaporation crystallization process is 80-95°C, and the evaporation concentration is carried out until crystals are precipitated; the washing crystals are washed at least twice with water at a temperature of 90-100°C.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The roasting described in the present invention is that the metal elements in the positive electrode material of the lithium ion battery react with concentrated hydrochloric acid to generate metal chlorides, and water vapor is introduced under high temperature conditions, so that the metal chlorides are selectively converted into soluble lithium chloride and other transition metal oxides, and then lithium separation is achieved by water leaching, and the water leaching liquid is further used to prepare lithium carbonate by precipitation method. The present invention uses the roasting-water leaching process to selectively extract lithium from waste lithium ion battery positive electrode materials, solving the problem of low lithium recovery rate and low purity of lithium products in traditional recycling processes; using the conversion process conditions of first chlorination and then hydrolysis, a cheaper chlorinating agent is introduced, and no impurity metal elements remain after roasting, solving the problem of impurity removal of impurity metals introduced by the chlorinating agent in the traditional chlorination roasting process. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A process flow chart of a method for selectively extracting lithium from waste lithium-ion battery positive electrode materials provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.

[0024] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0025] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0026] The positive electrode material powder of waste lithium-ion batteries in the embodiment of the present invention can be prepared by the existing waste battery pretreatment method, for example: disassembling the lithium battery to obtain the positive electrode sheet, and then separating the positive electrode material on the positive electrode sheet from the aluminum foil to obtain the positive electrode material powder. The positive electrode material powder of waste lithium-ion batteries in the following embodiments is derived from GEM Co., Ltd. It contains transition metal elements such as Ni, Co, and Mn. In the positive electrode powder of waste lithium batteries, the mass content of Li is 1-10%, the mass content of Ni is 0-70%, the mass content of Co is 0-70%, and the mass content of Mn is 0-70%, and Ni, Co, and Mn are not 0 at the same time.

[0027] like Figure 1 As shown, the method for selectively extracting lithium from waste lithium-ion battery positive electrode materials provided by the embodiment of the present invention specifically includes the following steps:

[0028] First, the waste lithium ion battery positive electrode material powder is sieved (preferably 200 mesh sieve), and then dried at 50-70°C for 20-30h. The dried waste lithium ion battery positive electrode material powder is evenly mixed with concentrated hydrochloric acid and placed in a roasting furnace, and water vapor is introduced. After heating to 300-750°C at a rate of 3-20°C / min, the temperature is kept for 0.5-2.0h (the preferred holding temperature of the roasting process is 500-700°C, and the holding time is 1.0-2.0h), wherein the flow rate of water vapor is 10-200mL / min. In this process, the mass fraction of concentrated hydrochloric acid is 36-38%, and the molar ratio of lithium in the waste lithium ion battery positive electrode material powder to chlorine in concentrated hydrochloric acid is 1:10-5.0, preferably 1:1.5-2.0, so as to ensure complete chlorination of lithium. This process achieves efficient conversion of lithium in the positive electrode material by adding concentrated hydrochloric acid and passing water vapor for calcination. The principle is as follows: the metal elements in the positive electrode material powder of waste lithium-ion batteries first react with concentrated hydrochloric acid to form metal chlorides. In a water vapor atmosphere and at a certain temperature, the metal chlorides are selectively converted, that is, lithium has been converted into soluble lithium chloride salts. During the hydrolysis process, lithium chloride is difficult to hydrolyze due to its harsh hydrolysis conditions and requirements for the atmosphere. The transition metals that have been converted into chlorides are converted into corresponding oxides. 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 For example, the reaction equation involved in the roasting process is as follows:

[0029] 3LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 +12HCl=3LiCl+NiCl 2 +CoCl 3 +MnCl4 +6H 2 O

[0030] 2NiCl 2 +H 2 O=2NiO+2HCl↑;

[0031] 2CoCl 3 +3H 2 O=Co 2 O 3 +6HCl↑;

[0032] MnCl 4 +2H 2 O=2MnO 2 +4HCl↑.

[0033] The above equation mainly includes the chlorination of the positive electrode material and the hydrolysis reaction of the metal chloride that occurs during the roasting process. Concentrated hydrochloric acid chlorinates the waste lithium-ion battery positive electrode material powder to form metal chloride. In the subsequent roasting process with water vapor, the transition metal chloride is hydrolyzed into metal oxides, achieving the selective chlorination of lithium.

[0034] After the calcination, the calcined product is obtained. To ensure good water leaching efficiency, the calcined product can be ground and passed through a 200-mesh sieve, and then water is added at a solid-liquid ratio of 50 to 250 g / L (more preferably 100 to 200 g / L) for stirring and water leaching. The temperature of the water leaching process is room temperature, the stirring speed is 100 to 800 rpm, and the time is 0.5 to 1.0 h to ensure sufficient leaching of lithium. After water leaching, the leaching solution and leaching residue are obtained by filtration, wherein the leaching residue is a transition metal oxide.

[0035] The lithium-rich leachate is evaporated and concentrated, and the specific evaporation and concentration temperature is 80-95°C, and the mass concentration of lithium is ≥10g / L (more preferably ≥20g / L). Then, alkali is added to the lithium-rich concentrated solution after evaporation and concentration to a pH of 10-12 to increase the yield of lithium carbonate, wherein the alkali is one or more of sodium hydroxide, potassium hydroxide or lithium hydroxide. After aging for 2-4 hours, sodium carbonate is added in a ratio of 0.60-0.75:1 to the molar ratio of sodium carbonate to lithium in the lithium-rich leachate to ensure that lithium is completely formed into lithium carbonate. Finally, evaporation and crystallization are carried out, and the crystals are washed to obtain lithium carbonate, wherein the evaporation and crystallization temperature is 80-95°C, and evaporation and concentration are carried out until crystals are precipitated, and finally the crystals are washed with hot water at 90-100°C for ≥2 times.

[0036] The above-mentioned roasting-water leaching process reacts the metal elements in the positive electrode material of the lithium-ion battery with concentrated hydrochloric acid to generate metal chlorides, and then introduces water vapor for high-temperature roasting to selectively convert the metal chlorides into soluble lithium chloride and other transition metal oxides, and then separates lithium through water leaching. The water leaching liquid is further used to prepare lithium carbonate by precipitation. The process is simple in steps, low in cost, high in lithium recovery rate, and good in separation effect, which solves the problem of low lithium recovery rate and low purity of lithium products in traditional recycling processes.

[0037] The above introduces the specific implementation methods of the present application. In order to objectively illustrate the technical effects produced by the present application, the following examples and comparative examples will be used for description.

[0038] Example 1

[0039] A method for selectively extracting lithium from waste lithium-ion battery positive electrode materials specifically comprises the following steps:

[0040] The waste lithium-ion battery powder was passed through a 200-mesh sieve and then dried at 60°C for 20 hours; 1.0g of the pretreated lithium nickel cobalt manganese oxide positive electrode material was weighed and 5.0ml of concentrated hydrochloric acid was placed in a mortar and ground and mixed evenly, then placed in a corundum porcelain boat, the porcelain boat was moved into a tube furnace and steam was introduced at a gas flow rate of 100ml / min, and the temperature was increased to 600°C at a heating rate of 5°C / min and kept warm for 60 minutes. The roasted product was ground and dissolved in 20ml of deionized water for water immersion at room temperature, and then filtered to obtain LiCl filtrate and transition metal oxide residue. The leaching rate of Li was 96.54% and the leaching rates of nickel, cobalt and manganese were 0.32%, 0.76% and 0.13% respectively as measured by ICP-OES. Sodium hydroxide was added to the filtrate after evaporation and concentration to adjust the pH to 12 to precipitate and filter impurities, and then 1.2 times the theoretical amount of sodium carbonate was added to evaporate and concentrate for precipitation. The lithium carbonate product was obtained by washing three times with 95°C deionized water. The purity of the lithium carbonate product was 98.72% after testing.

[0041] Example 2

[0042] A method for selectively extracting lithium from waste lithium-ion battery positive electrode materials specifically comprises the following steps:

[0043] The waste lithium-ion battery powder was passed through a 200-mesh sieve and then dried at 50°C for 30 hours; 1.0g of the pretreated lithium cobalt oxide positive electrode material was weighed and 2.5ml of concentrated hydrochloric acid was placed in a mortar and ground and mixed evenly, then placed in a corundum porcelain boat, the porcelain boat was moved into a tube furnace and steam was introduced at a gas flow rate of 20ml / min, and the temperature was increased to 700°C at a heating rate of 5°C / min and kept warm for 30 minutes. The roasted product was ground and dissolved in 20ml of deionized water for water immersion at room temperature, and then filtered to obtain LiCl filtrate and transition metal oxide residue. The leaching rate of Li and cobalt was measured by ICP-OES at this time. Sodium hydroxide was added to the filtrate after evaporation and concentration to adjust the pH to 12 for precipitation and filter impurities, and then 1.2 times the theoretical amount of sodium carbonate was added for evaporation and concentration for precipitation. The lithium carbonate product was washed 3 times with 95°C deionized water to obtain the lithium carbonate product. After testing, the purity of the lithium carbonate product was 99.31%.

[0044] Example 3

[0045] A method for selectively extracting lithium from waste lithium-ion battery positive electrode materials specifically comprises the following steps:

[0046] The waste lithium-ion battery powder was passed through a 200-mesh sieve and then dried at 60°C for 25 hours; 1.0g of the pretreated nickel-cobalt-manganese-oxide positive electrode material and 4.0ml of concentrated hydrochloric acid were weighed, mixed and placed in a corundum porcelain boat, the porcelain boat was moved into a tube furnace and steam was introduced at a gas flow rate of 150ml / min, and the temperature was increased to 650°C at a heating rate of 5°C / min and kept warm for 60 minutes. The calcined product was ground and dissolved in 30ml of deionized water for water immersion at room temperature, and then filtered to obtain LiCl filtrate and transition metal oxide residue. The leaching rate of Li was 96.42% and the leaching rates of nickel, cobalt and manganese were 1.22%, 1.38% and 0.67% respectively as measured by ICP-OES. Sodium hydroxide was added to the filtrate after evaporation and concentration to adjust the pH to 12 to precipitate and filter impurities, and then 1.2 times the theoretical amount of sodium carbonate was added to evaporate and concentrate for precipitation. The lithium carbonate product was obtained by washing three times with 95°C deionized water. The purity of the lithium carbonate product was 98.15% after testing.

[0047] Comparative Example 1

[0048] A method for selectively extracting lithium from waste lithium-ion battery positive electrode materials specifically comprises the following steps:

[0049] The waste lithium-ion battery powder was sieved through a 200-mesh sieve and then dried at 60°C for 25 hours; 1g of the pretreated nickel-cobalt-manganese oxide positive electrode material and 4.0ml of concentrated hydrochloric acid were weighed, mixed and placed in a corundum porcelain boat, and the porcelain boat was moved into a tube furnace without gas and heated to 650°C at a heating rate of 5°C / min and kept warm for 60 minutes. The calcined product was ground and dissolved in 30ml of deionized water and soaked at room temperature, and then filtered to obtain LiCl filtrate and transition metal oxide residue. The leaching rate of Li was 84.43% and the leaching rates of nickel, cobalt and manganese were 63.83%, 44.33% and 59.05% respectively by ICP-OES, and the selective extraction of lithium could not be achieved.

[0050] According to the above-mentioned Example 3 and the comparative example, the hydrolysis of transition metal chlorides during the roasting process needs to be carried out under the condition of passing water vapor. The closed condition will lead to a sharp decrease in the metal separation efficiency, and the selective lithium extraction cannot be achieved. Under the conditions of the present invention, after chlorination and roasting under water vapor conditions, transition metals such as nickel, cobalt and manganese can be hydrolyzed to generate corresponding oxides. The leaching rate is low in the subsequent water leaching process, while the leaching rate of lithium can reach 96.54%. The subsequent pH adjustment precipitation process can further remove the transition metal ions to obtain high-purity lithium carbonate.

[0051] In summary, the present invention uses concentrated hydrochloric acid and water vapor to chlorinate and hydrolyze the positive electrode active material of waste lithium-ion batteries, thereby achieving efficient and selective extraction of lithium, and the recovery rate of lithium can be increased to more than 90%. The process involved in the present invention is simple, the chemical reagents used are low-priced, economical and environmentally friendly, and easy to realize industrialization.

[0052] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A method for selectively extracting lithium from waste lithium-ion battery positive electrode materials, characterized in that: The method comprises the following steps: S1. Mixing the waste lithium-ion battery positive electrode material powder and concentrated hydrochloric acid uniformly and then roasting to obtain a roasted product; introducing water vapor during the roasting process; S2, leaching the roasted product in water, and filtering to obtain lithium-rich leaching solution and leaching residue; S3, concentrating the lithium-rich leachate, adding alkali, aging, and filtering to obtain a filtrate, and then adding sodium carbonate to the filtrate for post-treatment to obtain lithium carbonate.

2. The method for selectively extracting lithium from waste lithium-ion battery positive electrode materials according to claim 1, characterized in that: Before step S1, the waste lithium-ion battery powder is sieved and then dried at 50-70° C. for 20-30 hours.

3. The method for selectively extracting lithium from waste lithium-ion battery positive electrode materials according to claim 1, characterized in that: During the roasting process of step S1, the water vapor is introduced at a flow rate of 10 to 200 ml / min.

4. The method for selectively extracting lithium from waste lithium-ion battery positive electrode materials according to claim 1, characterized in that: The calcination process is as follows: heating to 300-750° C. at a rate of 3-20° C. / min and then keeping the temperature for 0.5-2.0 h.

5. The method for selectively extracting lithium from waste lithium-ion battery positive electrode materials according to claim 1, characterized in that: The molar ratio of lithium in the waste lithium ion battery positive electrode material powder to chlorine in concentrated hydrochloric acid is 1:1.0-5.

0.

6. The method for selectively extracting lithium from waste lithium-ion battery positive electrode materials according to claim 1, characterized in that: During the water immersion process in step S2, the solid-liquid ratio of the roasted product to water is 50-250 g / L, and the product is stirred at a speed of 100-800 rpm for 0.5-1.0 h during the water immersion process.

7. The method for selectively extracting lithium from waste lithium-ion battery positive electrode materials according to claim 1, characterized in that: In the step S3, the concentration process specifically includes: evaporating and concentrating the lithium-rich leaching solution at a temperature of 80-95° C. to a lithium mass concentration of ≥10 g / L.

8. The method for selectively extracting lithium from waste lithium-ion battery positive electrode materials according to claim 1, characterized in that: In the step S3, alkali is added until the pH value of the lithium-rich concentrated solution is 10-12, and the alkali is one or more of sodium hydroxide, potassium hydroxide or lithium hydroxide; and the aging time is 2-4 hours.

9. The method for selectively extracting lithium from waste lithium-ion battery positive electrode materials according to claim 1, characterized in that: The molar ratio of lithium to sodium carbonate in the lithium-rich leaching solution is 1:0.60-0.

75.

10. The method for selectively extracting lithium from waste lithium-ion battery positive electrode materials according to claim 1, characterized in that: The post-treatment process includes evaporative crystallization and crystal washing; The temperature of the evaporation crystallization process is 80-95° C., and the evaporation concentration is performed until crystals are precipitated; the washed crystals are washed at least twice with water at a temperature of 90-100° C.

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