Method for efficiently recovering valuable metals from waste ternary positive electrode material step by step

Abstract

The invention discloses a method for efficiently recovering valuable metals from a waste ternary positive electrode material step by step. According to the method, the layered structure of the ternary positive electrode material is successfully destroyed through a sodium thiosulfate and glucose composite salt reduction roasting method, lithium is converted into soluble sulfate, and transition metal is converted into water-insoluble metal oxide, so that preconditions are provided for selective lithium extraction; and meanwhile, the generated metal oxide is more beneficial to subsequent roasting compared with a metal phase. According to the method, sodium thiosulfate and glucose composite salt are adopted for carbon-sulfur combined roasting, so that the reaction limit is reduced, and the reaction temperature and the reaction time are successfully reduced. And roasting can be performed in air, so that the whole process operation is facilitated. According to the method, the loss rate of lithium in the whole process can be reduced through two times of roasting and cyclic utilization of the leachate, the extremely high extraction rate of lithium is achieved, and a new thought is provided for recycling of the waste ternary positive electrode material.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium battery processing, and in particular relates to a method for efficiently and step-by-step recovering valuable metals from waste ternary positive electrode materials. Background Art

[0002] The life of lithium batteries is generally 8-10 years. The ternary lithium batteries of early new energy vehicles have begun to be gradually retired. It is foreseeable that more and more batteries will be retired in the future. The discarded ternary batteries themselves are a kind of waste with great harm. If they are not properly handled, they will cause great harm to the environment. If they can be recycled reasonably, it can not only alleviate environmental problems and resource pressure, but also bring huge economic benefits.

[0003] The recycling of waste lithium-ion batteries is a hot spot for competition among countries around the world. It faces problems such as precise separation, high-value and high-value conversion. It is necessary to break through the challenges of low cost, high recovery, high value and less pollution. Europe, the United States, Japan and South Korea use pyrometallurgy as the leading technology and wet process as the auxiliary route. China mainly uses wet process technology and pyrometallurgy as the auxiliary. Improving lithium recovery indicators is the focus. Short-process direct regeneration technology has not yet been industrialized, and performance indicators need to be improved. Wet recovery often requires a large amount of acid and alkali, which makes the recycling process more polluting. With the increasingly stringent environmental protection policies, the disadvantage of this method of generating a large amount of waste liquid will become more obvious. The pyrometallurgy also has problems such as low recovery efficiency and difficulty in separation, which greatly reduces the subsequent economic benefits. The improvement of lithium recovery indicators has also become the key to the development of recycling technology. It is urgent to develop new technologies for lithium extraction and recycling of ternary waste lithium-ion battery positive electrode materials with revolutionary ideas.

[0004] At present, the recycling process of waste ternary lithium batteries mostly adopts the method of direct dissolution with sulfuric acid, which will lead to the use of a large amount of sulfuric acid. Another one-stage roasting method, such as using ammonium sulfate, is to directly roast the waste ternary positive electrode material and then soak it in water. In the above methods, a solution mixed with nickel, cobalt, manganese and a large amount of lithium elements will be obtained. In the subsequent treatment process, if the precursor is directly precipitated after impurities are removed, the high concentration of lithium liquid will cause a large amount of lithium to be taken away, thereby greatly reducing the recovery rate of lithium. If the metal is extracted after acid dissolution, the process is very complicated. The extraction process cannot directly obtain a high value-added precursor, and lithium can only be extracted after the extraction is completed. Summary of the invention

[0005] In view of the above problems, the object of the present invention is to provide a method for efficiently recovering valuable metals from waste ternary positive electrode materials in steps.

[0006] The object of the present invention is achieved by a method for efficiently recovering valuable metals from waste ternary cathode materials in steps, which is achieved by the following steps: 1) One-stage calcination: Mix the waste ternary cathode material black powder with sodium thiosulfate and glucose in a ratio of 6:3:1 and then calcine at 400-500°C for 1-3h in air atmosphere; 2) taking half of the roasted product obtained in step 1), crushing it into pieces of 0.5-2 mm, and then soaking it in water, stirring it thoroughly, and filtering it to obtain a first filter residue and a first filtrate, and washing the first filter residue with water to obtain a second filter residue; 3) In step 2), the first filtrate is adjusted in pH to remove F, phosphorus, aluminum, iron and organic matter to obtain a lithium-rich solution, and then a sodium carbonate solution is added, and stirred at 70-95° C. for 0.5-1 h, and crude lithium carbonate and a leachate are obtained by precipitation and filtration; the crude lithium carbonate is washed 3-5 times with water at 70-95° C. to obtain refined lithium carbonate; 4) Second stage roasting: drying the second filter residue obtained in step 2) and mixing it with sodium persulfate at a mass ratio of 1:1-2, roasting it in an oxygen atmosphere, crushing the roasted product to a particle size of 0.5-2 mm, and leaching it in water to obtain a leachate; wherein the oxygen ventilation rate is 100-250 ml / min, and the roasting time is 3-4 h; 5) The product obtained in step 4) is leached in water, and the leaching solution is adjusted in pH to remove F, phosphorus, aluminum and iron elements therein. The pH of the obtained solution is adjusted to 10-11, and then precipitated at 40-60° C. for 2-4 hours and filtered. The filter residue obtained after filtration is the crude precursor; 6) washing the crude precursor obtained in step 5) with water for multiple times to obtain a refined precursor; 7) Recover the remaining roasting product from step 1) according to the method of steps 1) to 6).

[0007] The principle of the method of the present invention is as follows: The chemical reaction during the selective lithium extraction process is: C 6 H 12 O 6 + Na 2 S 2 O 3 →4CO(g)+ Na 2 S + 6H 2 O + 2C + 2S; 2C+O 2 (g)→2CO(g) LiNi 0.5 Co 0.2 Mn 0.3 O 2 +C+Na 2 S+7 / 2O 2 (g)→1 / 2Li 2 SO4 +1 / 2NiO+1 / 5CoO+3 / 10MnO+Na 2 SO 4 +CO 2 (g) LiNi 0.5 Co 0.2 Mn 0.3 O 2 +CO(g)+Na 2 S 2 O 3 →1 / 2Li 2 SO 4 +1 / 2NiO+1 / 5CoO+3 / 10MnO+ Na 2 SO 4 +CO 2 (g); Reaction formula of impurity removal process: Fe 3+ +OH 1 + →Fe(OH)3↓; Al 3+ +P 3+ →AlP↓; The chemical reaction during the second-stage transition metal roasting process is: CoO+Na 2 S 2 O 8 →CoSO 4 +Na 2 SO 4； NiO+Na 2 S 2 O 8 →NiSO 4 +Na 2 SO 4； MnO+Na 2 S 2 O 8 →MnSO 4 +Na 2 SO 4； The chemical reaction during the precursor precipitation process is: CoSO 4 +2NaOH → Na 2 SO 4 +Co(OH) 2 ↓; NiSO 4 +2NaOH → Na 2 SO4 +Ni(OH) 2 ↓; MnSO 4 +2NaOH → Na 2 SO 4 +Co(OH) 2 ↓; The beneficial effects of the present invention are as follows: the present invention successfully destroys the layered structure of the ternary positive electrode material through the method of reduction roasting with sodium thiosulfate and glucose composite salt, converts lithium into soluble sulfate, and converts transition metals into water-insoluble metal oxides, which provides a prerequisite for selective lithium extraction. At the same time, the generated metal oxide is more conducive to subsequent roasting than the metal phase.

[0008] The present invention adopts sodium thiosulfate and glucose composite salt for carbon-sulfur co-roasting, which reduces the reaction limit and successfully reduces the reaction temperature and reaction time. And it can be roasted in the air, which is convenient for the whole process operation. At the same time, the two-stage roasting in the present invention greatly reduces the amount of acid used, making the whole process safer and more environmentally friendly. The present invention can reduce the loss rate of lithium in the whole process through two roastings and the recycling of the leaching solution, and achieves a lithium extraction rate of up to 96%, which provides a new idea for the recovery of waste ternary positive electrode materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 The XRD diagram of the waste positive electrode material of Examples 1-3 of the present invention; Figure 2 This is the SEM image of the waste positive electrode material of Examples 1-3 of the present invention; Figure 3 is a process flow chart of the present invention; Figure 4 The XRD diagram of lithium sulfate and transition metal oxides after calcination in step 1 of Example 1; Figure 5 This is the SEM image of the transition metal product after water immersion in step 2 of Example 1; Figure 6 This is a graph showing changes in impurity removal content in step 2 of Example 1; Figure 7 The XRD pattern of the crude lithium carbonate obtained in step 2 of Example 1; Figure 8 The XRD pattern of the lithium carbonate product obtained in step 2 of Example 1; Fig. 9 The XRD pattern of the transition metal sulfate obtained by the second-stage roasting product in step 3 of Example 1; Fig.10 The XRD diagram of lithium sulfate and transition metal oxides after calcination in step 1 of Example 2; Fig.11The XRD pattern of the lithium carbonate product obtained in step 2 of Example 2; Fig.12 The XRD pattern of the transition metal sulfate of the two-stage calcination product obtained in step 3 of Example 2; Fig.13 The XRD diagram of lithium sulfate and transition metal oxides after calcination in step 1 of Example 3; Fig.14 The XRD pattern of the lithium carbonate product obtained in step 2 of Example 3; Fig.15 This is the XRD pattern of the transition metal sulfate of the two-stage calcination product obtained in step 3 of Example 3. DETAILED DESCRIPTION

[0010] The present invention is further described below, but the present invention is not limited in any way. Any changes made based on the present invention belong to the protection scope of the present invention.

[0011] The present invention provides a method for efficiently recovering valuable metals from waste ternary cathode materials in steps, which is achieved by the following steps: 1) One-stage calcination: Mix the waste ternary cathode material black powder with sodium thiosulfate and glucose in a ratio of 6:3:1 and then calcine at 400-500°C for 1-3h in air atmosphere; 2) taking half of the roasted product obtained in step 1), crushing it into pieces of 0.5-2 mm, and then soaking it in water, stirring it thoroughly, and filtering it to obtain a first filter residue and a first filtrate, and washing the first filter residue with water to obtain a second filter residue; 3) In step 2), the first filtrate is adjusted in pH to remove F, phosphorus, aluminum, iron and organic matter to obtain a lithium-rich solution, and then a sodium carbonate solution is added, and stirred at 70-95° C. for 0.5-1 h, and crude lithium carbonate and a leachate are obtained by precipitation and filtration; the crude lithium carbonate is washed 3-5 times with water at 70-95° C. to obtain refined lithium carbonate; 4) Second stage roasting: drying the second filter residue obtained in step 2) and mixing it with sodium persulfate at a mass ratio of 1:1-2, roasting it in an oxygen atmosphere, crushing the roasted product to a particle size of 0.5-2 mm, and leaching it in water to obtain a leachate; wherein the oxygen ventilation rate is 100-250 ml / min, and the roasting time is 3-4 h; 5) The product obtained in step 4) is leached in water, and the leaching solution is adjusted in pH to remove F, phosphorus, aluminum and iron elements therein. The pH of the obtained solution is adjusted to 10-11, and then precipitated at 40-60° C. for 2-4 hours and filtered. The filter residue obtained after filtration is the crude precursor; 6) washing the crude precursor obtained in step 5) with water for multiple times to obtain a refined precursor; 7) Recover the remaining roasting product from step 1) according to the method of steps 1) to 6).

[0012] In step 2), the liquid-to-solid ratio of water immersion is 1:3-5, the liquid-to-solid ratio of the first filter residue water washing is 1.5-2:1, the number of water washings is 1, and the water washing temperature is 35°C.

[0013] In step 3), the method for removing F, phosphorus, aluminum and iron elements is as follows: adding a defluorinating agent to the first filtrate, and adding sodium hydroxide to adjust the pH to 7-9, stirring, filtering, adding sulfuric acid to the obtained filtrate to adjust the pH to 2-5, filtering, and then adding hydrogen peroxide to remove organic matter.

[0014] In step 3), the concentration of the sodium carbonate solution is 150-300 g / L.

[0015] In step 3), the liquid-to-solid ratio of the crude lithium carbonate washing is 2-3:1, and the washing water can be used to prepare the sodium carbonate solution.

[0016] In step 3), the leachate is adjusted to pH 1-3 to release carbonate ions, converting sodium carbonate in the solution into sodium sulfate, and then sodium hydroxide is added to adjust the pH to 6-7.5, and evaporated and concentrated to 20-40% of the original volume at 95°C, and then filtered to obtain a filter residue and a filtrate, wherein the filter residue is sodium sulfate, and the filtrate is incorporated into the lithium-rich solution in the recovery process of step 7).

[0017] In step 4), the liquid-to-solid ratio of the water immersion is 1.5-3:1; In step 5), the method for removing F, phosphorus, aluminum and iron elements is as follows: adding a defluorinating agent to the leachate, adding sodium hydroxide to adjust the pH to 7-9, stirring, filtering, and then adding sulfuric acid to the obtained filtrate to adjust the pH to 2-5, stirring, and filtering.

[0018] In step 6), the precursor water washing liquid-to-solid ratio is 1.5-4:1, the water washing times are 2-5 times, and the washing water is used as the immersion water in step 4).

[0019] The washing water in step 2) and the filtrate obtained in step 5) are used as water for soaking the roasted product in step 2) during the recovery process in step 7).

[0020] The chemical composition content of the waste positive electrode materials in Examples 1-3 is shown in Table 1: Table 1 Chemical composition of waste positive electrode materials in Examples 1-3 Example 1 A method for efficiently recovering valuable metals from waste ternary materials in steps, comprising the following steps: 1. Take 12kg of waste ternary cathode material, mix it with 6kg of sodium thiosulfate and 2kg of glucose, and roast it at 400℃ for 1h to obtain the roasted product (such as Figure 4As shown, the main characteristic peaks of the calcined product are consistent with those of sodium lithium sulfate, and compared with Figure 1 The characteristic peak of the waste positive electrode material has completely disappeared). Take 10kg of the roasted product and leached it with water at a liquid-to-solid ratio of 4:1. After leaching, filter and separate to obtain leached residue and leached liquid. Wash the leached residue with 20L of clean water for subsequent use, and obtain about 6kg of leached residue. Figure 5 It can be seen that the characteristic peaks of the leached residue do not contain the characteristic peaks of the ternary positive electrode material and are mainly composed of transition metal oxides.

[0021] 2. By adjusting the pH of the leachate, F, phosphorus, aluminum, iron elements and organic matter are removed, and a lithium-rich solution is obtained by filtering. The specific steps are as follows: 8 g of a defluorinating agent is added to the first filtrate according to a mass ratio of 2:1 between the defluorinating agent and the total fluorine content in the leachate, and sodium hydroxide is added to adjust the pH to 7, and stirred for 30 minutes. After removing the precipitate, the mixture is stirred at 50°C for 60 minutes to finally form an aluminum phosphide precipitate. The precipitate is filtered, sulfuric acid is added to adjust the pH to 3, and the mixture is stirred for 70 minutes to form a hydroxide precipitate. After filtering, hydrogen peroxide is added according to 0.2% of the total volume, and the pH is adjusted to 1.5 to oxidize the excess organic matter to CO 2 Release. The content of each element in the leaching solution before and after impurity removal is as follows Figure 6 shown.

[0022] Then sodium carbonate was added to the lithium-rich solution and stirred at 85°C for 1 hour to precipitate lithium to obtain crude lithium carbonate (from Figure 7 It can be seen that the crude lithium carbonate contains non-lithium carbonate impurities) and leachate. The crude lithium carbonate was washed three times with 85°C water at a liquid-to-solid ratio of 2:1 to obtain refined lithium carbonate (from Figure 8 It can be seen that the characteristic peak of refined lithium carbonate completely corresponds to the characteristic peak of lithium carbonate, and its purity can reach 99.78%). The composition detection results are shown in Table 2.

[0023] The pH of the leachate is adjusted to 1 to release carbonate ions, and the sodium carbonate in the solution is converted into sodium sulfate. Sodium hydroxide is then added to adjust the pH to 6, and then evaporated and concentrated at 95°C to 30% of the original volume, and then filtered to obtain a filter residue and a filtrate, wherein the filter residue is sodium sulfate, and the filtrate is incorporated into the lithium-rich solution of the next recovery process.

[0024] Table 2 Content of various substances in the refined lithium carbonate obtained in Example 1 element Main content Al F Na P S content 99.78% 0.0035% 0.0008% 0.066% 0.0031% 0.044% 3. The leached residue obtained in step 1 was mixed with 6 kg of sodium persulfate and roasted at 400 ° C for 3 h to obtain a roasted product ( Fig. 9 ), the oxygen flow rate is 100ml / min, and then 20L of water is added to obtain the leachate.

[0025] 4. Remove phosphorus, aluminum, fluorine and iron elements in the leachate of step 3 according to the method in step 2, adjust the pH to 10.5, precipitate at 60°C for 4 hours and filter, and the obtained filter residue is a crude precursor. The component content in the filtrate is shown in Table 3. Only a small amount of Mn is dissolved in the first roasting and leaching process of nickel, cobalt and manganese, and Ni and Co are basically completely recovered, while the recovery rate of Mn is 99.9% due to the first water leaching dissolution.

[0026] The obtained crude precursor was washed with water three times at a liquid-to-solid ratio of 2:1 to obtain a refined precursor, and the washing water was used as the immersion water in step 3 of the next recovery process. Table 3 Component contents in the filtrate after precursor impurity removal, precipitation and filtration 5. The remaining roasted product in step 1 is recovered for the second time according to the above method, wherein the roasted product uses 20L of the washing liquid after the first stage of roasting in step 1 and the filtrate after the precipitation of the precursor in step 4 as the water leaching liquid, and the shortage is supplemented with 40L of clean water, the second filtrate obtained in step 2 is incorporated into the lithium-rich solution, and the washing liquid in step 4 is mixed with clean water to 20L as the second stage water leaching liquid. It is calculated that the final lithium recovery rate after the secondary recovery is 96.3%, the nickel and cobalt recovery rates are 100%, and the manganese recovery rate is 99.98%.

[0027] Example 2 A method for efficiently recovering valuable metals from waste ternary materials in steps, comprising the following steps: 1. Take 6kg of waste ternary cathode material, mix it with 3kg of sodium thiosulfate and 1kg of glucose, and roast it at 500℃ for 2h to obtain the roasted product (such as Fig.10 As shown, the main characteristic peaks of the calcined product are consistent with those of sodium lithium sulfate, and compared with Figure 1 The characteristic peak of the waste positive electrode material has completely disappeared). 5 kg of the calcined product was leached in water at a liquid-to-solid ratio of 5:1. After leaching, the leached residue and the leached liquid were separated by filtration. The leached residue was washed with 10 L of clean water for subsequent use, and about 3 kg of leached residue was obtained.

[0028] 2. By adjusting the pH of the leachate, F, phosphorus, aluminum, iron elements and organic matter are removed, and a lithium-rich solution is obtained by filtering. The specific steps are as follows: 2 g of defluoridation agent is added to the first filtrate according to a mass ratio of 1:1 between the defluoridation agent and the total amount of fluorine, and sodium hydroxide is added to adjust the pH to 7, and stirred for 30 minutes. After removing the precipitate, the pH is maintained at 7, and stirred at 40°C for 60 minutes to finally form an aluminum phosphide precipitate. The precipitate is filtered, sulfuric acid is added to adjust the pH to 5, and stirred for 60 minutes to form a hydroxide precipitate. After filtering, hydrogen peroxide is added at a mass ratio of 0.5%, and the pH is adjusted to 2 to oxidize the excess organic matter to CO 2 release.

[0029] Then sodium carbonate was added to the lithium-rich solution and stirred at 70°C for 1 hour to precipitate lithium, thereby obtaining crude lithium carbonate and leaching solution. The crude lithium carbonate was washed twice with 90°C water at a liquid-to-solid ratio of 2.5:1 to obtain refined lithium carbonate (from Fig.11 It can be seen that the XRD pattern of refined lithium carbonate is completely consistent with the standard card), and its component detection results are shown in Table 4.

[0030] The pH of the leaching solution is adjusted to 3 to release carbonate ions, and the sodium carbonate in the solution is converted into sodium sulfate. Sodium hydroxide is then added to adjust the pH to between 7, and then evaporated and concentrated at 95°C to 25% of the original volume, and then filtered to obtain a filter residue and a filtrate, wherein the filter residue is sodium sulfate, and the filtrate is incorporated into the lithium-rich solution of the next recovery process.

[0031] Table 4 Content of various substances in the refined lithium carbonate obtained in Example 2 element Main content Al F Na P S content 99.8% 0.0027% 0.0007% 0.058% 0.0007% 0.041% 3. The leached residue obtained in step 1 was mixed with 3 kg of sodium persulfate and roasted at 400 ° C for 3 h to obtain a roasted product (from Fig.12 It can be seen that the transition metal oxides are all converted into sulfates), wherein the oxygen flow rate is 100 ml / min. Then 15 L of water is used for 2 hours to obtain the leachate.

[0032] 4. Remove phosphorus, aluminum, fluorine and iron elements from the leachate in step 3 according to the method in step 2, adjust the pH to 11, precipitate at 40°C for 2 hours and filter, and the obtained filter residue is a crude precursor. The obtained crude precursor was washed twice with water at a liquid-to-solid ratio of 4:1 to obtain a refined precursor, and the washing water was used as the immersion water in step 3 of the next recovery process. 5. The remaining roasted product in step 1 is recovered for the second time according to the above method, wherein the roasted product is used as the water leaching liquid for the first stage of water leaching, which is 25L of the washing liquid after the first stage of roasting in step 1 and the filtrate after the precipitation of the precursor in step 4. If it is less than 25L, it is supplemented with clean water. The second filtrate obtained in step 2 is incorporated into the lithium-rich solution, and the washing liquid of the precursor in step 4 is supplemented with clean water to 15L for the second stage of water leaching. It is calculated that the final lithium recovery rate after the secondary recovery is 96.11%, the nickel and cobalt recovery rates are 100%, and the manganese recovery rate is 99.98%.

[0033] Example 3 A method for efficiently recovering valuable metals from waste ternary materials in steps, comprising the following steps: 1. Take 18kg of waste ternary cathode material, mix it with 9kg of sodium thiosulfate and 3kg of glucose, and roast it at 450℃ for 2h to obtain the roasted product (such as Fig.13 As shown, the main characteristic peaks of the calcined product are consistent with those of sodium lithium sulfate, and compared with Figure 1The characteristic peak of the waste positive electrode material has completely disappeared). Take 15kg of the roasted product and soak it in 50L of water (liquid-solid ratio is about 3.33:1). After the leaching is completed, filter and separate to obtain the leached residue and the leached liquid. Wash the leached residue with 18L of clean water for subsequent use, and obtain about 9kg of leached residue.

[0034] 2. By adjusting the pH of the leachate, F, phosphorus, aluminum, iron elements and organic matter are removed, and a lithium-rich solution is obtained by filtering. The specific steps are as follows: 18 g of a defluorinating agent is added to the first filtrate according to a mass ratio of 3:1 between the defluorinating agent and the total fluorine content in the leachate, and sodium hydroxide is added to adjust the pH to 9, and stirred for 30 minutes. After removing the precipitate, the pH is adjusted to 8.5, and stirred at 70°C for 60 minutes to finally form an aluminum phosphide precipitate. The precipitate is filtered, sulfuric acid is added to adjust the pH to 5, and stirred for 90 minutes to form a hydroxide precipitate. After filtering, hydrogen peroxide is added at a mass ratio of 0.5%, and the pH is adjusted to 3 to oxidize the excess organic matter to CO 2 release.

[0035] Then sodium carbonate was added to the lithium-rich solution and stirred at 95°C for 0.5h to precipitate lithium to obtain crude lithium carbonate and leachate. The crude lithium carbonate was washed four times with 95°C water at a liquid-to-solid ratio of 2.5:1 to obtain refined lithium carbonate ( Fig.14 ), and the component detection results are shown in Table 5.

[0036] The pH of the leaching solution is adjusted to 2 to release carbonate ions, and the sodium carbonate in the solution is converted into sodium sulfate. Sodium hydroxide is then added to adjust the pH to between 7.5, and then evaporated and concentrated at 95°C to 20% of the original volume, and then filtered to obtain a filter residue and a filtrate, wherein the filter residue is sodium sulfate, and the filtrate is incorporated into the lithium-rich solution of the next recovery process.

[0037] Table 5 Content of various substances in the refined lithium carbonate obtained in Example 3 element Main content Al F Na P S content 99.73% 0.0037% 0.00094% 0.068% 0.0028% 0.0474% 3. The leached residue obtained in step 1 was mixed with 9 kg of sodium persulfate and roasted at 400 ° C for 3 h to obtain a roasted product (from Fig.15 It can be seen that nickel, cobalt and manganese have all been converted into sulfates, among which transition metals have all been oxidized into sulfates, and the oxygen flow rate is 100 ml / min. Then 32L of water is used for 2h to obtain the leachate.

[0038] 4. Remove phosphorus, aluminum, fluorine and iron elements from the leachate in step 3 according to the method in step 2, adjust the pH to 11, precipitate at 40°C for 2 hours and filter, and the obtained filter residue is a crude precursor. The obtained crude precursor was washed twice with water at a liquid-to-solid ratio of 3:1 to obtain a refined precursor, and the washing water was used as the immersion water in step 3 of the next recovery process. 5. The remaining roasted product in step 1 is recovered for the second time according to the above method, wherein the roasted product uses the washing liquid after the first roasting in step 1 and the filtrate after the precursor precipitation in step 4 as the water leaching liquid, the second filtrate obtained in step 2 is incorporated into the lithium-rich solution, and the washing water in step 4 is used as the leachate for the second water leaching. It is calculated that the final lithium recovery rate after the secondary recovery is 95.9%, the nickel and cobalt recovery rate is 100%, and the manganese recovery rate is 99.99%.

Claims

1. A method for efficiently recovering valuable metals from waste ternary cathode materials in steps, characterized in that: To do this, follow these steps: 1) One-stage calcination: Mix the waste ternary cathode material black powder with sodium thiosulfate and glucose in a ratio of 6:3:1 and then calcine at 400-500°C for 1-3h in air atmosphere; 2) taking half of the roasted product obtained in step 1), crushing it into pieces of 0.5-2 mm, and then soaking it in water, stirring it thoroughly, and filtering it to obtain a first filter residue and a first filtrate, and washing the first filter residue with water to obtain a second filter residue; 3) In step 2), the first filtrate is adjusted in pH to remove F, phosphorus, aluminum, iron and organic matter to obtain a lithium-rich solution, and then a sodium carbonate solution is added, and stirred at 70-95° C. for 0.5-1 h, and crude lithium carbonate and a leachate are obtained by precipitation and filtration; the crude lithium carbonate is washed 3-5 times with water at 70-95° C. to obtain refined lithium carbonate; 4) Second stage roasting: drying the second filter residue obtained in step 2) and mixing it with sodium persulfate at a mass ratio of 1:1-2, roasting it in an oxygen atmosphere, crushing the roasted product to a particle size of 0.5-2 mm, and leaching it in water to obtain a leachate; wherein the oxygen ventilation rate is 100-250 ml / min, and the roasting time is 3-4 h; 5) The product obtained in step 4) is leached in water, and the leaching solution is adjusted in pH to remove F, phosphorus, aluminum and iron elements therein. The pH of the obtained solution is adjusted to 10-11, and then precipitated at 40-60° C. for 2-4 hours and filtered. The filter residue obtained after filtration is the crude precursor; 6) washing the crude precursor obtained in step 5) with water for multiple times to obtain a refined precursor; 7) Recover the remaining roasting product from step 1) according to the method of steps 1) to 6).

2. The method for efficiently recovering valuable metals from waste ternary cathode materials according to claim 1, characterized in that: In step 2), the liquid-to-solid ratio of water immersion is 1:3-5, the liquid-to-solid ratio of the first filter residue water washing is 1.5-2:1, the number of water washings is 1, and the water washing temperature is 35°C.

3. The method for efficiently recovering valuable metals from waste ternary cathode materials according to claim 1, characterized in that: In step 3), the method for removing F, phosphorus, aluminum and iron elements is as follows: sodium hydroxide is added to the first filtrate to adjust the pH to 7-9, and then a defluorinating agent is added, stirred, and filtered. Sulfuric acid is added to the obtained filtrate to adjust the pH to 2-5, and filtered.

4. The method for efficiently recovering valuable metals from waste ternary cathode materials according to claim 1, characterized in that: In step 3), the concentration of the sodium carbonate solution is 150-300 g / L.

5. The method for efficiently recovering valuable metals from waste ternary cathode materials according to claim 1, characterized in that: In step 3), the liquid-to-solid ratio of the crude lithium carbonate washing is 2-3:1, and the washing water can be used to prepare the sodium carbonate solution.

6. The method for efficiently recovering valuable metals from waste ternary cathode materials according to claim 1, characterized in that: In step 3), the leachate is adjusted to pH 1-3 to release carbonate ions, converting sodium carbonate in the solution into sodium sulfate, and then sodium hydroxide is added to adjust the pH to 6-7.5, and evaporated and concentrated to 20-40% of the original volume at 95°C, and then filtered to obtain a filter residue and a filtrate, wherein the filter residue is sodium sulfate, and the filtrate is incorporated into the lithium-rich solution in the recovery process of step 7).

7. The method for efficiently recovering valuable metals from waste ternary cathode materials according to claim 1, characterized in that: In step 4), the liquid-to-solid ratio of the water immersion is 1.5-3:

1.

8. The method for efficiently recovering valuable metals from waste ternary cathode materials according to claim 1, characterized in that: In step 5), the method for removing F, phosphorus, aluminum and iron elements is as follows: sodium hydroxide is added to the leachate to adjust the pH to 7-9, stirred, filtered, and then sulfuric acid is added to the obtained filtrate to adjust the pH to 2-5, stirred, and filtered.

9. The method for efficiently recovering valuable metals from waste ternary cathode materials according to claim 1, characterized in that: In step 6), the precursor water washing liquid-to-solid ratio is 1.5-4:1, the water washing times are 2-5 times, and the washing water is used as the immersion water in step 4).

10. The method for efficiently recovering valuable metals from waste ternary cathode materials according to claim 1, characterized in that: The washing water in step 2) and the filtrate obtained in step 5) are used as water for soaking the roasted product in step 2) during the recovery process in step 7).

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