Efficient extraction method for recycling valuable metal from waste potassium battery positive electrode powder

Abstract

The invention relates to the technical field of battery recovery, in particular to an efficient extraction method for recovering valuable metal from waste potassium battery positive electrode powder. The method comprises the following steps: 1, pretreatment; 2, preparing raw materials; according to the efficient extraction method for recycling the valuable metal from the waste potassium battery positive electrode powder, under the combination and synergistic effect of the raw materials and the combination of the sulfuric acid and the hydrogen peroxide leaching agent with the concentration range controlled, the structure of a metal compound can be specifically destroyed, indissolvable metal can be oxidized, a proper amount of sodium gluconate serves as a complexing agent to intervene in good time, and the leaching efficiency is improved. The metal ions are tightly complexed with dissolved-out metal ions, so that the stability of the metal ions in the solution is improved, and the metal ions are prevented from re-precipitating or being adsorbed by impurities; the leaching efficiency of the valuable metal is improved, meanwhile, subsequent separation and purification of the valuable metal are facilitated, the product quality is improved, resource loss is reduced, pollution to the environment is reduced, and therefore the high efficiency of waste battery recycling is improved.

Description

Technical Field

[0001] The invention relates to the technical field of battery recycling, in particular to an efficient leaching method for recovering valuable metals from positive electrode powder of waste potassium batteries. Background Art

[0002] With the rapid development of the global new energy industry, potassium batteries are increasingly used. However, after potassium batteries reach the end of their service life, if they are not properly handled, their waste batteries will cause many serious problems. On the one hand, if the valuable metals such as lithium, cobalt, nickel, and manganese contained in waste potassium batteries cannot be effectively recovered, it will cause a huge waste of resources, because these metals have limited reserves in nature and high mining costs, while the battery industry's demand for them continues to grow. On the other hand, harmful substances in waste potassium batteries may seep out and pollute the ecological environment such as soil and water.

[0003] At present, there are some shortcomings in the traditional methods of recycling waste batteries. For example, physical methods such as simple mechanical crushing and screening can separate battery components to a certain extent, but it is difficult to achieve fine separation of metals and other substances, and the recovery rate of valuable metals is low; pyrometallurgical processes require a high temperature environment, huge energy consumption, increased cost consumption, and may produce harmful gas emissions during the process, causing secondary pollution to the atmospheric environment; in addition, traditional hydrometallurgical processes not only reduce the selectivity of the metal leaching process, causing a variety of impurities to be leached together with valuable metals, increasing the difficulty and cost of subsequent separation and purification, but also reduce the activity of metal ions in the leaching process, affecting the further reaction of metal ions with the leaching agent, so that the leaching rate of the metal is limited, thereby reducing the efficiency of waste battery recycling.

[0004] In view of this, there is an urgent need for an efficient leaching method to recover valuable metals from spent potassium battery cathode powder. Summary of the invention

[0005] The object of the present invention is to provide an efficient leaching method for recovering valuable metals from waste potassium battery positive electrode powder, so as to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides an efficient leaching method for recovering valuable metals from waste potassium battery positive electrode powder, comprising the following steps:

[0007] S1. Pretreatment: dismantle the waste potassium battery, separate the positive electrode part, and then use a ball mill to grind the positive electrode material into positive electrode powder;

[0008] S2. Raw material preparation: positive electrode powder, leaching agent and sodium gluconate;

[0009] S3, leaching process: add the positive electrode powder to a reaction vessel equipped with a stirring device, a heating device and a condensation reflux device, then add the leaching agent and sodium gluconate, turn on the stirring device and the heating device to mix the components evenly, and at the same time, the condensation reflux device stabilizes the flow rate of the cooling water so that the steam can be fully condensed and refluxed, and during the reaction process, the reaction system is sampled, and then the leaching concentration of the metal ions is detected by an atomic absorption spectrometer;

[0010] S4, solid-liquid separation: after the extraction is completed, the leachate and the remaining solid residue are separated by a filter press to obtain the solid residue and leachate. Then, the solid residue is washed 6 to 8 times to remove the leachate remaining on the surface of the residue;

[0011] S5, leachate treatment: a high-speed centrifuge is used to remove impurities and purify the leachate to improve the purification effect, and then activated carbon is added to the leachate for adsorption treatment, and a stirring device is used to stir at room temperature so that residual organic matter and some heavy metal ion impurities in the leachate are adsorbed by the activated carbon, and then a filter cloth is used to filter the leachate to obtain a further purified leachate;

[0012] S6. Recovery of valuable metals: Recovery of valuable metals is carried out according to the different metals.

[0013] As a further improvement of the technical solution, in S1, the grinding speed of the ball mill is 40r / min-70r / min, the grinding time is 30min-60min, and the particle size of the positive electrode powder is 50μm-100μm.

[0014] As a further improvement of the technical solution, S2 includes the following raw materials in mass percentage:

[0015] Positive electrode powder: the mass percentage of the positive electrode powder is 4.7%-16.4%;

[0016] Leaching agent: The mass percentage of the leaching agent is 82.0%-94.8%;

[0017] Sodium gluconate: The mass percentage of the sodium gluconate is 0.9%-2.7%.

[0018] As a further improvement of the technical solution, in S2, the leaching agent is sulfuric acid (H 2 SO 4 ) and hydrogen peroxide (H 2 O 2 ) in a mixed solution, wherein the concentration of sulfuric acid is 1 mol / L-2 mol / L, and the concentration of hydrogen peroxide is 0.5 mol / L-1 mol / L.

[0019] As a further improvement of the technical solution, in S3, the stirring speed of the stirring device is 300r / min-500r / min; the heating device is heated to 60℃-80℃, and, during the reaction, the temperature fluctuates to -2℃-2℃.

[0020] As a further improvement of the technical solution, in S3, in the entire reaction system, the reaction time is 2h-4h, and the reaction system is sampled every 40min-60min.

[0021] As a further improvement of the technical solution, in S4, the pressure of the filter press is 0.3MPa-0.5MPa.

[0022] As a further improvement of the present technical solution, in S5, the rotation speed of the high-speed centrifuge is 6000r / min-10000r / min.

[0023] As a further improvement of the technical solution, in S5, the amount of activated carbon added is 1%-3% of the mass of the leaching solution; the stirring speed of the stirring device is 200r / min-300r / min, and the stirring time is 40min-60min.

[0024] As a further improvement of the present technical solution, in S6, the valuable metal recovery of different metals includes lithium metal recovery, cobalt metal recovery, nickel metal recovery and manganese metal recovery.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] In the high-efficiency leaching method for recovering valuable metals from the positive electrode powder of waste potassium batteries, the combination of sulfuric acid and hydrogen peroxide leaching agents with controlled concentration ranges can specifically destroy the structure of metal compounds and oxidize insoluble metals, while an appropriate amount of sodium gluconate is timely intervened as a complexing agent to closely complex with the dissolved metal ions, thereby improving the stability of the metal ions in the solution and preventing them from re-precipitating or being adsorbed by impurities; not only the leaching efficiency of the valuable metals is improved, but also the subsequent separation and purification of the valuable metals is facilitated, product quality is improved, resource loss is reduced, and pollution to the environment is reduced, thereby improving the high efficiency of waste battery recycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The flowchart of the efficient leaching method for recovering valuable metals from the positive electrode powder of waste potassium batteries of the present invention is as follows;

[0028] Figure 2 A bar graph showing the purity of valuable metals extracted according to the present invention;

[0029] Figure 3 It is a bar chart of the valuable metal leaching recovery rate of the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the accompanying drawings in the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0031] according to Figure 1 As shown, the embodiment of the present invention provides an efficient leaching method for recovering valuable metals from waste potassium battery positive electrode powder, comprising the following steps:

[0032] Step 1, pretreatment: disassemble the waste potassium battery, separate the positive electrode part, and then use a ball mill to grind the positive electrode material into positive electrode powder. The grinding speed of the ball mill is 40r / min-70r / min, the grinding time is 30min-60min, and the particle size of the positive electrode powder is 50μm-100μm;

[0033] Step 2: Raw material preparation: positive electrode powder, leaching agent and sodium gluconate; including the following raw materials in percentage by mass:

[0034] Positive electrode powder: The mass percentage of positive electrode powder is 4.7%-16.4%;

[0035] Leaching agent: The mass percentage of the leaching agent is 82.0%-94.8%; the leaching agent is sulfuric acid (H 2 SO 4 ) and hydrogen peroxide (H 2 O 2 ) wherein the concentration of sulfuric acid is 1 mol / L-2 mol / L and the concentration of hydrogen peroxide is 0.5 mol / L-1 mol / L;

[0036] Sodium gluconate: The mass percentage of sodium gluconate is 0.9%-2.7%;

[0037] Step 3, leaching process: add the positive electrode powder to a reaction vessel with a stirring device, a heating device and a condensation reflux device, then add the leaching agent and sodium gluconate, turn on the stirring device and the heating device, the stirring speed of the stirring device is 300r / min-500r / min; the heating device is heated to 60℃-80℃, and, during the reaction process, the temperature fluctuates at -2℃-2℃, so that the components are mixed evenly, and at the same time, the condensation reflux device stabilizes the flow rate of the cooling water so that the steam can be fully condensed and refluxed to reduce the volatilization loss of the solution, and, during the reaction process, the reaction system is sampled. In the entire reaction system, the reaction time is 2h-4h, and the reaction system is sampled every 40min-60min, and then an atomic absorption spectrometer is used to detect the leaching concentration of metal ions;

[0038] Step 4, solid-liquid separation: After the extraction is completed, the leachate and the remaining solid residue are separated by a filter press. The pressure of the filter press is 0.3MPa-0.5MPa to prevent the solid residue from penetrating the filter medium or damaging the equipment due to excessive pressure. The obtained solid residue and leachate are then washed 6-8 times to remove the leachate remaining on the surface of the residue;

[0039] Step 5, leachate treatment: a high-speed centrifuge is used to remove impurities and purify the leachate, and the rotation speed of the high-speed centrifuge is 6000r / min-10000r / min to improve the purification effect, and then activated carbon is added to the leachate for adsorption treatment, and the amount of activated carbon added is 1%-3% of the mass of the leachate; and a stirring device is used to stir at room temperature, and the stirring speed of the stirring device is 200r / min-300r / min, and the stirring time is 40min-60min, so that the residual organic matter and some heavy metal ion impurities in the leachate are adsorbed by the activated carbon, and then a filter cloth is used to filter to obtain a further purified leachate;

[0040] Step 6. Recovery of valuable metals: The recovery of valuable metals is targeted at different metals. The recovery of valuable metals of different metals includes lithium metal recovery, cobalt metal recovery, nickel metal recovery and manganese metal recovery.

[0041] In the invention, the waste potassium battery is first disassembled and the positive electrode powder is ground, which can not only make the positive electrode powder particle size uniform and improve the activity, but also increase the contact area with the reagent to promote the reaction and improve the leaching efficiency. At the same time, the process parameters of each step are controlled, such as stabilizing the temperature and flow rate during leaching, and using operations such as stirring, heating and condensation reflux during leaching, which can not only effectively improve the purity and recovery rate of valuable metal recovery and reduce the impurity content, but also effectively improve the overall effect of valuable metal recovery and reduce resource waste and environmental pollution.

[0042] In addition, after the leaching agent promotes the dissolution of metals in the positive electrode powder, sodium gluconate combines with the leaching agent for a second time. The reaction mechanism is that sulfuric acid ionizes hydrogen ions to destroy the structure of metal compounds and release metal ions, and hydrogen peroxide synergistically oxidizes insoluble metal substances. Sodium gluconate, by virtue of its multi-functional group characteristics, complexes with metal ions, which can effectively improve the metal leaching efficiency and stability.

[0043] Through the combination and synergistic effect of the raw materials, and the combination of sulfuric acid and hydrogen peroxide leaching agents with controlled concentration range, the structure of metal compounds can be targeted and the insoluble metals can be oxidized. An appropriate amount of sodium gluconate is timely intervened as a complexing agent to closely complex with the dissolved metal ions, thereby improving the stability of the metal ions in the solution and preventing them from re-precipitating or being adsorbed by impurities. This not only improves the leaching efficiency of valuable metals, but is also beneficial to the subsequent separation and purification of valuable metals, improves product quality, reduces resource losses, and reduces pollution to the environment, thereby improving the efficiency of waste battery recycling.

[0044] Different valuable metals are recovered according to the amount of different raw materials used. The recovery of valuable metals from the positive electrode powder provided by the present invention is further illustrated through the following specific examples.

[0045] Example 1

[0046] Raw material dosage: 50g positive electrode powder (mass percentage about 8.5%), 530ml leaching agent (sulfuric acid concentration 1.5mol / L, hydrogen peroxide concentration 0.7mol / L, mass percentage about 90.7%), sodium gluconate 1.5g (mass percentage about 0.8%);

[0047] For lithium metal recovery: the leachate obtained after leaching is firstly distilled under reduced pressure to remove part of the water, so that the solution is concentrated to about one third of the original volume, and then the concentrated leachate is placed in a crystallizer and slowly cooled to 5°C-10°C for 2h-3h, lithium sulfate crystals are precipitated, and high-purity lithium sulfate crystals are obtained by centrifugal separation, and then dried to obtain the finished product;

[0048] Reaction formula: LiMn 2 O 4 +4H 2 SO 4 +H 2 O 2 →Li 2 SO 4 +2MnSO 4 +4H 2 OO 2 ↑.

[0049] Example 2

[0050] Raw material dosage: positive electrode powder 30g (mass percentage about 4.7%), leaching agent 600ml (sulfuric acid concentration 1mol / L, hydrogen peroxide concentration 0.5mol / L, mass percentage about 94.8%), sodium gluconate 0.9g (mass percentage about 0.9%);

[0051] For the recovery of cobalt metal: the leachate is mixed with di(2-ethylhexyl) phosphate extractant at a volume ratio of 1:6, stirred at a stirring speed of 250r / min for 20min, and allowed to stand for 40min, the cobalt ions enter the organic phase, and then 2mol / L hydrochloric acid solution is mixed with the cobalt-containing organic phase at a volume ratio of 1:3 for back extraction, stirred for 15min, allowed to stand for stratification, and the aqueous phase is evaporated and concentrated to obtain cobalt sulfate crystals, which are then washed and dried to obtain the cobalt product;

[0052] Reaction formula: CoOOH+H 2 SO 4 →CoSO 4 +H 2 OO 2 ↑.

[0053] Example 3

[0054] Raw material dosage: positive electrode powder 70g (mass percentage about 11.3%), leaching agent 500ml (sulfuric acid concentration 1.8mol / L, hydrogen peroxide concentration 0.9mol / L, mass percentage about 82.0%), sodium gluconate 2.1g (mass percentage about 2.7%);

[0055] For nickel metal recovery: the leachate is passed through a chelating resin column for ion exchange at a controlled flow rate of 1 ml / min. After saturation, the nickel ions are eluted with a 1 mol / L ammonium sulfate solution. The eluate is collected and heated for evaporation and concentration. When the solution density reaches 1.4 g / cm 3 -1.6g / cm 3 When the temperature is 400 °C, the heating is stopped, the mixture is cooled and crystallized, and nickel sulfate crystals are obtained by centrifugation, and the nickel product is obtained by drying;

[0056] Reaction formula: NiO+H 2 SO 4 →NiSO 4 +H 2 O.

[0057] Example 4

[0058] Raw material dosage: positive electrode powder 40g (mass percentage about 6.3%), leaching agent 580ml (sulfuric acid concentration 1.2mol / L, hydrogen peroxide concentration 0.6mol / L, mass percentage about 93.3%), sodium gluconate 1.2g (mass percentage about 0.4%);

[0059] For manganese metal recovery: first add calcium hydroxide emulsion to the leachate to adjust the pH to 6-7, so that impurity ions such as iron and aluminum form precipitation, filter to remove the precipitation, then add sodium sulfide solution to the filtrate to precipitate heavy metal ions such as copper and lead, filter again, and finally heat the filtrate to evaporate and concentrate. When the solution is close to saturation, stop heating, cool and crystallize, filter to obtain manganese sulfate crystals, and wash and dry to obtain manganese products;

[0060] Reaction formula: NiO+H 2 SO 4 →NiSO 4 +H 2 O+H 2 SO 4 +H 2 O 2 →MnSO 4 +2H 2 OO 2 ↑.

[0061] Table 1 Amount of each raw material used in Examples 1-4

[0062] Example 1 Example 2 Example 3 Example 4 Positive electrode powder (%) 8.5 4.7 11.3 6.3 Leaching agent (%) 90.7 94.8 82.0 93.3 Sodium gluconate (%) 1.5 0.9 2.1 1.2 Valuable metal recovery (types) Lithium Metal Recovery Cobalt Metal Recovery Nickel Metal Recovery Manganese Metal Recovery

[0063] In order to verify that the valuable metals recovered from the positive electrode powder prepared in the embodiment of the present invention have good purity and recovery rate, the valuable metals recovered from the positive electrode powder provided in the embodiment of the present invention are described through the following test examples.

[0064] Test example

[0065] The purpose of this experimental group is to explore the effects of different component ratios on the recovery of valuable metals from positive electrode powder.

[0066] Experimental objective: To detect the purity and recovery rate of the leaching of different valuable metals by the present invention, and to recover the composition ratio of valuable metals by using the positive electrode powder provided in Examples 1-4 through Experimental Group A, Experimental Group B, Experimental Group C and Experimental Group D respectively; the control examples use Control Group A, Control Group B, Control Group C and Control Group D.

[0067] Experimental method: The experimental group A, experimental group B, experimental group C and experimental group D respectively adopted the extraction methods provided in Examples 1-4, and the control group A, control group B, control group C and control group D adopted the following extraction method:

[0068] Control group A

[0069] Pretreatment: Dismantle the waste potassium battery and separate the positive electrode part, but the positive electrode material is not ground by a ball mill, and the original positive electrode material is directly used for subsequent operations;

[0070] Raw material preparation: the same as in Example 1;

[0071] Leaching process: Add unground positive electrode powder into the reaction vessel, add leaching agent and sodium gluconate. Set the stirring speed to 300r / min, heat to 60℃, and the reaction time to 2h. No sampling operation is performed during the reaction process.

[0072] Solid-liquid separation: Use filter press to separate leachate and solid residue. The pressure of filter press is 0.3MPa. Wash the solid residue three times.

[0073] Leachate treatment: Use a high-speed centrifuge to remove impurities and purify the leachate, the centrifuge rotation speed is 4000r / min; add 1% activated carbon of the leachate mass to the leachate, stir at room temperature at a stirring speed of 200r / min for 40min, and then filter;

[0074] Valuable metal recovery: For lithium metal recovery, the leachate is directly evaporated and crystallized without vacuum distillation and concentration to one-third of the volume.

[0075] Control group B

[0076] Pretreatment: After disassembling the waste potassium battery, the positive electrode material is ground into positive electrode powder using a common grinding method (non-ball mill, low grinding efficiency), and the grinding time is 20 minutes;

[0077] Raw material preparation: Prepare the raw materials according to the mass percentage of positive electrode powder, leaching agent and sodium gluconate, but the concentration of sulfuric acid in the leaching agent is 0.5 mol / L, and the concentration of hydrogen peroxide is 0.3 mol / L;

[0078] Leaching process: Add the positive electrode powder to the reaction vessel, add the leaching agent and sodium gluconate. Set the stirring speed to 200r / min, heat to 50℃, and the reaction time to 1.5h; do not perform condensation reflux operation;

[0079] Solid-liquid separation: Use filter press to separate the leachate and solid residue. The pressure of filter press is 0.2MPa. Wash the solid residue twice.

[0080] Leachate treatment: Use a high-speed centrifuge to remove impurities and purify the leachate, the centrifuge rotation speed is 12000r / min; add 0.5% of the mass of the leachate activated carbon to the leachate, stir at room temperature at a stirring speed of 100r / min for 30min, and then filter;

[0081] Recovery of valuable metals: For the recovery of cobalt metal, the leachate and the extractant are mixed in a volume ratio of 1:4, stirred at a speed of 150r / min, stirred for 10 minutes, and allowed to stand for 20 minutes for stratification; 1 mol / L hydrochloric acid solution is mixed with the cobalt-containing organic phase in a volume ratio of 1:2 for back extraction, stirred for 10 minutes, and then the aqueous phase is evaporated and concentrated.

[0082] Control group C

[0083] Pretreatment: disassemble the waste potassium battery, separate the positive electrode part, and use a ball mill to grind the positive electrode material into positive electrode powder. The grinding speed of the ball mill is 30r / min, the grinding time is 25min, and the particle size of the positive electrode powder is 40μm.

[0084] Raw material preparation: the same as in Example 3, but without adding sodium gluconate;

[0085] Extraction process: Add the positive electrode powder to the reaction vessel, add the leaching agent, set the stirring speed to 250r / min, heat to 70°C, the reaction time is 3h, sample the reaction system every 70min, and the flow rate of the cooling water in the condensation reflux device is unstable;

[0086] Solid-liquid separation: A filter press was used to separate the leachate and the solid residue. The pressure of the filter press was 0.4 MPa, and the solid residue was washed 7 times.

[0087] Leachate treatment: Use a high-speed centrifuge to remove impurities and purify the leachate, with a centrifuge rotation speed of 8000r / min. Add 2% activated carbon to the leachate, stir at room temperature at a stirring speed of 250r / min for 50 minutes, and then filter;

[0088] Valuable metal recovery: For nickel metal recovery, the leachate is passed through a chelating resin column for ion exchange, with a flow rate of 1.5 ml / min. After saturation, the nickel ions are eluted with a 0.8 mol / L ammonium sulfate solution. The eluate is collected, heated and evaporated, and concentrated. When the solution density reaches 1.3 g / cm 3 When the temperature is high, the heating is stopped, the product is cooled and crystallized, and nickel sulfate crystals are obtained by centrifugation, which is then dried to obtain a nickel product.

[0089] Control group D

[0090] Pretreatment: disassemble the waste potassium battery, separate the positive electrode part, and use a ball mill to grind the positive electrode material into positive electrode powder. The grinding speed of the ball mill is 80r / min, the grinding time is 70min, and the particle size of the positive electrode powder is 120μm.

[0091] Raw material preparation: the same as in Example 4, except that the concentration of sulfuric acid in the leaching agent is 2.5 mol / L, and the concentration of hydrogen peroxide is 1.2 mol / L;

[0092] Extraction process: Add positive electrode powder to the reaction vessel, add leaching agent and sodium gluconate; set the stirring speed to 550r / min, heat to 85°C, and the reaction time to 4.5h; sample the reaction system every 30min; the flow rate of cooling water in the condensation reflux device is too fast;

[0093] Solid-liquid separation: A filter press was used to separate the leachate and the solid residue. The pressure of the filter press was 0.6 MPa, and the solid residue was washed 9 times.

[0094] Leachate treatment: Use a high-speed centrifuge to remove impurities and purify the leachate, the centrifuge rotation speed is 6000r / min; add 4% activated carbon of the leachate mass to the leachate, stir at room temperature at a stirring speed of 350r / min for 70min, and then filter;

[0095] Recovery of valuable metals: For the recovery of manganese metal, calcium hydroxide emulsion is first added to the leachate to adjust the pH to 8, so that impurity ions such as iron and aluminum form precipitation, and the precipitation is filtered out. Then sodium sulfide solution is added to the filtrate to precipitate heavy metal ions such as copper and lead. The filtrate is filtered again and finally the filtrate is heated and evaporated to concentrate. When the solution is close to saturation, the heating is stopped, cooled and crystallized, and manganese sulfate crystals are filtered to obtain the manganese product after washing and drying.

[0096] Specific detection indicators are shown in Table 2.

[0097] Table 2 Test indicators of each sample

[0098] Valuable Metals purity(%) Recovery rate (%) Experimental Group A Lithium Metal 95 85 Test Group B Cobalt Metal 92 81 Test Group C Nickel Metal 90 84 Test Group D Manganese Metal 88 78 Control group A Lithium Metal 70 65 Control group B Cobalt Metal 65 62 Control group C Nickel Metal 58 45 Control group D Manganese Metal 62 56

[0099] according to Figure 2 , Figure 3 As shown in Table 2, the summary of the above comparative data is as follows:

[0100] Purity:

[0101] The purity of precious metals in the experimental group AD was significantly higher than that in the control group AD;

[0102] For lithium metal recovery, the purity of test group A is 95%, while that of control group A is only 70%, indicating that the pretreatment step in the embodiment of the present invention (grinding the positive electrode material into positive electrode powder with uniform particle size using a ball mill) and precise leaching process parameter control (such as temperature, stirring speed, reaction time, etc.) play an important role in improving the purity of lithium metal; the positive electrode material (control group A) that has not been ground by a ball mill may result in a small reaction contact area and impurities are difficult to remove, thereby reducing the purity of lithium metal;

[0103] In the recovery of cobalt metal, the purity of test group B reached 92%, while that of control group B was 65%. The good effect of test group B lies in its control of the steps such as leaching agent concentration, stirring speed, heating temperature and condensation reflux operation, which is conducive to the efficient leaching of cobalt metal and the removal of impurities. The control group B adopts the ordinary grinding method and the leaching agent concentration is low, and lacks the condensation reflux operation, resulting in the lower purity of cobalt metal.

[0104] For nickel metal recovery, the purity of test group C was 90%, and that of control group C was 58%. The addition of sodium gluconate and a stable condensation reflux device in test group C helped to improve the purity of nickel metal, while sodium gluconate was not added to control group C, and the flow rate of cooling water in the condensation reflux device was unstable, which affected the leaching and purification effect of nickel metal.

[0105] In terms of manganese metal recovery, the purity of test group D was 88%, and that of control group D was 62%. The process parameters controlled by test group D (such as grinding speed, leaching agent concentration, stirring speed, etc.) improved the efficient leaching and purity of manganese metal. The purity of manganese metal in control group D was lower due to factors such as long grinding time, high leaching agent concentration, and too fast flow rate of cooling water in the condensation reflux device.

[0106] Recycling rate:

[0107] The recovery rate of valuable metals in the experimental group AD was also higher than that in the control group AD;

[0108] In the recovery of lithium metal, the recovery rate of the test group A was 85%, and that of the control group A was 65%. The operations of vacuum distillation concentration, slow cooling crystallization, etc. in the embodiment of the present invention are helpful to improve the recovery rate of lithium metal, while the control group A directly evaporates and crystallizes the leachate, resulting in insufficient crystallization of some lithium metal, and a low recovery rate;

[0109] For the recovery of cobalt metal, the recovery rate of test group B reached 81%, and that of control group B was 62%. The test group B improved the efficient recovery of cobalt metal through operations such as stirring, stratification, and stripping. The control group B had a lower recovery rate of cobalt metal due to factors such as unreasonable stirring speed and time, and short stratification time.

[0110] In terms of nickel metal recovery, the recovery rate of test group C was 84%, and that of control group C was 45%. The stable ion exchange operation and appropriate eluent concentration in test group C helped to improve the recovery rate of nickel metal. The recovery rate of nickel metal in control group C was lower due to improper control of ion exchange flow rate and other factors.

[0111] In the recovery of manganese metal, the recovery rate of the experimental group D was 78%, and that of the control group D was 56%. The experimental group D ensured the recovery of manganese metal by adjusting the pH value, precipitating impurities, and concentrating and crystallizing. The control group D had its manganese metal recovery rate affected by factors such as improper pH adjustment.

[0112] It can be seen that in the entire recovery process, the operation and parameter control of each step play an important role in the purity and recovery rate of valuable metals, from the grinding of positive electrode materials in the ball mill in the pretreatment stage, to the strict control of stirring speed, heating temperature, reaction time, condensation reflux in the leaching process, to the reasonable operation of solid-liquid separation and leachate treatment, and the special recovery operations for different valuable metals, all of which have a higher purity and recovery rate of valuable metals; in contrast, the control group has problems in various links such as inappropriate grinding, improper leaching agent concentration, inaccurate control of operating parameters, resulting in significantly lower purity and recovery rate of valuable metals than the test group. The present invention can not only efficiently recover valuable metals from waste potassium battery positive electrode powder, but also reduce resource waste and environmental pollution, thereby improving the efficiency of the leaching method.

[0113] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An efficient leaching method for recovering valuable metals from waste potassium battery cathode powder, characterized in that: The following steps are involved: S1. Pretreatment: dismantle the waste potassium battery, separate the positive electrode part, and then use a ball mill to grind the positive electrode material into positive electrode powder; S2. Raw material preparation: positive electrode powder, leaching agent and sodium gluconate; S3, leaching process: add the positive electrode powder to a reaction vessel equipped with a stirring device, a heating device and a condensation reflux device, then add the leaching agent and sodium gluconate, turn on the stirring device and the heating device to mix the components evenly, and at the same time, the condensation reflux device stabilizes the flow rate of the cooling water so that the steam can be fully condensed and refluxed, and during the reaction process, the reaction system is sampled, and then the leaching concentration of the metal ions is detected by an atomic absorption spectrometer; S4, solid-liquid separation: after the extraction is completed, the leachate and the remaining solid residue are separated by a filter press to obtain the solid residue and leachate. Then, the solid residue is washed 6 to 8 times to remove the leachate remaining on the surface of the residue; S5, leachate treatment: a high-speed centrifuge is used to remove impurities and purify the leachate to improve the purification effect, and then activated carbon is added to the leachate for adsorption treatment, and a stirring device is used to stir at room temperature so that residual organic matter and some heavy metal ion impurities in the leachate are adsorbed by the activated carbon, and then a filter cloth is used to filter the leachate to obtain a further purified leachate; S6. Recovery of valuable metals: Recovery of valuable metals is carried out according to the different metals.

2. The efficient leaching method for recovering valuable metals from waste potassium battery cathode powder according to claim 1, characterized in that: In S1, the grinding speed of the ball mill is 40 r / min-70 r / min, the grinding time is 30 min-60 min, and the particle size of the positive electrode powder is 50 μm-100 μm.

3. The efficient leaching method for recovering valuable metals from waste potassium battery cathode powder according to claim 1, characterized in that: The S2 includes the following raw materials in percentage by weight: Positive electrode powder: the mass percentage of the positive electrode powder is 4.7%-16.4%; Leaching agent: The mass percentage of the leaching agent is 82.0%-94.8%; Sodium gluconate: The mass percentage of the sodium gluconate is 0.9%-2.7%.

4. The efficient leaching method for recovering valuable metals from waste potassium battery cathode powder according to claim 1, characterized in that: In the S2, the leaching agent is a mixed solution of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2), wherein the concentration of sulfuric acid is 1 mol / L-2 mol / L, and the concentration of hydrogen peroxide is 0.5 mol / L-1 mol / L.

5. The efficient leaching method for recovering valuable metals from waste potassium battery cathode powder according to claim 1, characterized in that: In S3, the stirring speed of the stirring device is 300r / min-500r / min; the heating device is heated to 60°C-80°C, and during the reaction, the temperature fluctuates between -2°C and 2°C.

6. The efficient leaching method for recovering valuable metals from waste potassium battery cathode powder according to claim 1, characterized in that: In S3, in the entire reaction system, the reaction time is 2h-4h, and the reaction system is sampled every 40min-60min.

7. The efficient leaching method for recovering valuable metals from waste potassium battery cathode powder according to claim 1, characterized in that: In S4, the pressure of the filter press is 0.3MPa-0.5MPa.

8. The efficient leaching method for recovering valuable metals from waste potassium battery cathode powder according to claim 1, characterized in that: In S5, the rotation speed of the high-speed centrifuge is 6000r / min-10000r / min.

9. The efficient leaching method for recovering valuable metals from waste potassium battery cathode powder according to claim 1, characterized in that: In the S5, the amount of activated carbon added is 1%-3% of the mass of the leaching solution; the stirring speed of the stirring device is 200r / min-300r / min, and the stirring time is 40min-60min.

10. The efficient leaching method for recovering valuable metals from waste potassium battery cathode powder according to claim 1, characterized in that: In S6, the valuable metal recovery of different metals includes lithium metal recovery, cobalt metal recovery, nickel metal recovery and manganese metal recovery.

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