A mixed solution treatment method and application thereof

Abstract

The present invention discloses a method for treating a mixed solution and its application, belonging to the technical field of wastewater treatment. In the treatment method provided by the present invention, the mixed solution contains at least one of Ni<supgt;2+< / supgt>, Co<supgt;2+< / supgt>, and Mn<supgt;2+< / supgt>, and Li<supgt;+< / supgt>; the treatment method includes the following steps: S1. Extracting the mixed solution with organic phase A to obtain a loaded organic phase A and a raffinate phase A; the organic phase A includes the extractant Cyphos IL 104; in the organic phase A, the volume fraction of the extractant Cyphos IL 104 is 30% - 100%; the pH of the mixed solution is 6 - 9. The treatment method provided by the present invention can respectively recover transition metal elements and lithium elements in the mixed solution, and the recovery rate is very high. The present invention also provides an application of the above treatment method.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a mixed solution treatment method and application thereof. Background Art

[0002] Under the general trend of global energy transformation, the new energy industry is booming. According to statistics, the sales of new energy vehicles have increased by more than 50% annually in the past five years, and the energy storage market is also expanding rapidly. This has led to a sharp increase in the demand for lithium batteries. It is estimated that by 2025, the global lithium battery production will exceed 10 million tons.

[0003] However, the life of lithium batteries is limited, and as time goes by, the problem of waste lithium batteries has become increasingly prominent. At present, the number of waste lithium batteries generated each year has reached millions of tons, and is still increasing at a rate of about 20% per year. It is worth noting that these waste lithium batteries contain many valuable metals. For example, ternary lithium batteries contain Li, Co, Mn and Ni at the same time. If these waste batteries are not handled properly, the valuable metals, especially transition metals, will cause serious pollution to the soil and water sources. The toxic substances such as organic and inorganic compounds contained in them are very likely to undergo various chemical reactions in the environment and thus pollute the environment, produce carcinogenicity, and endanger human health. In addition, the reserves of transition metals and lithium are limited and unevenly distributed. From a resource perspective, recycling lithium batteries can effectively alleviate the tight supply of key metal resources such as lithium and cobalt. Therefore, recycling waste lithium batteries is of great significance and necessity, which can not only alleviate the pressure of resource shortages, but also reduce environmental hazards and promote sustainable development.

[0004] At present, the recycling methods of waste lithium batteries mainly include pyrometallurgy, hydrometallurgy and mechanical and physical methods. Pyrometallurgy technology is mature and has a large processing capacity. For example, a large recycling plant can process 50,000 tons of waste lithium batteries every year, but the energy consumption is high, usually consuming thousands of kilowatt-hours of electricity per ton of processing. Hydrometallurgy has a high metal recovery rate, which can reach more than 90%, but its process flow is complicated and the cost of wastewater treatment is high. Mechanical and physical methods are relatively simple and low-cost, but the metal recovery rate is generally around 60%.

[0005] According to the above comparison, from the perspective of resource utilization, hydrometallurgy has certain advantages, but the hydrometallurgical process in related technologies also has significant defects. For example, most technologies cannot fully recover valuable metals, which to a certain extent causes insufficient resource utilization and waste; for another example, most technologies attempt to fully recover valuable metals, but the overall recovery rate of valuable metals needs to be improved.

[0006] In addition to lithium batteries, there are many waste materials containing a variety of valuable metals in the industry, such as transition metal catalysts, mining and smelting waste slag, etc. Among them, transition metal resources such as nickel, cobalt and manganese also urgently need to be recycled. The recycling methods, current status and types of valuable metals in them are similar to those of lithium batteries.

[0007] Therefore, it is of great significance to provide a simple and easy method for recovering valuable metals in solution and improving its overall recovery rate. Summary of the invention

[0008] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a method for treating a mixed solution, which can respectively recover transition metal elements and lithium elements in the mixed solution with a high recovery rate.

[0009] The invention also provides application of the above processing method.

[0010] According to an embodiment of the first aspect of the present invention, a method for treating a mixed solution is provided, wherein the mixed solution contains Ni 2+ 、Co 2+ , Mn 2+ At least one of + ; The processing method comprises the following steps:

[0011] S1. Extracting the mixed solution with an organic phase A to obtain a loaded organic phase A and a raffinate phase A;

[0012] The organic phase A comprises the extractant Cyphos IL 104 (trihexyl(tetradecyl)phosphine bicyclo(2,4,4-trimethylpentyl)phosphine, molecular formula C 48 H 102 O2P2, CAS: 465527-59-7);

[0013] In the organic phase A, the volume fraction of the extractant Cyphos IL 104 is 30% to 100%;

[0014] The pH of the mixed solution is 6-9.

[0015] According to some embodiments of the present invention, the mechanism of the processing method is as follows:

[0016] After the extraction, the Ni in the mixed solution 2+ 、Co 2+ , Mn 2+ At least one of the above is transferred to the loaded organic phase A, Li + Remain in the raffinate phase A.

[0017] The processing method according to the embodiment of the present invention has at least the following beneficial effects:

[0018] The present invention adopts a solvent extraction method to treat the mixed solution, uses an environmentally friendly ionic liquid as an extractant to extract and separate the metals, and further designs and optimizes the extraction conditions so that the organic phase A including the ionic liquid extractant has good selective extraction properties for Co, Mn and Ni, and has the characteristics of high extraction rate and high purity of recovered metal products, thereby greatly improving the utilization rate of resources; the treatment method provided by the present invention has no energy consumption (energy saving), and at the same time, the process generates less waste and can greatly reduce pollution to the environment (environmental protection), and the entire process is short, simple and highly operable, which can make up for the shortcomings of related technologies and solve the problems existing in the hydrometallurgical process.

[0019] Specifically, the present invention avoids the decomposition failure of the organic phase A and the hydrolysis precipitation of transition metal ions by controlling the pH value; at the same time, the Li + The extraction of transition metal ions is improved, and the extraction rate of transition metals is ≥99%;

[0020] The present invention effectively controls the viscosity of the organic phase A by controlling the volume fraction of the extractant Cyphos IL 104 in the organic phase A, thereby optimizing the mass transfer rate of the extraction in step S1, and facilitating the control of the O / A ratio in the later stage, thereby achieving the concentration and precipitation of transition metal ions (later stage); within this concentration range, the separation of transition metal ions and lithium ions can also be effectively achieved, and transition metal ions, especially Co 2+ and Ni 2+ If the concentration of the extractant is lower than the range required by the present invention, even if the O / A ratio is adjusted to ensure that there is enough extractant Cyphos IL 104 in the extraction process, Ni cannot be efficiently achieved. 2+ 、Co 2+ , Mn 2+ The co-extraction, specific, Co 2+ The extraction efficiency can be reduced to about 35%, Ni 2+ The extraction efficiency can be reduced to about 5%.

[0021] According to some embodiments of the present invention, the mixed solution is a leachate of a solid substance; the solid substance includes at least one of a lithium battery positive electrode material, a transition metal catalyst and a transition metal mineral.

[0022] According to some embodiments of the present invention, the positive electrode material of the lithium battery includes lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMnO2), binary positive electrode material (LiMO2, M is two of nickel, cobalt and manganese), ternary NCM (LiNi x Coy Mn 1-x-y O2) and at least one of lithium manganate (LiMn2O4).

[0023] According to some embodiments of the present invention, the leaching solution is an acid leaching solution. For example, the specific method of obtaining the leaching solution may be:

[0024] The solid substance, the acid solution and the hydrogen peroxide are mixed and reacted, and then the solid-liquid separation is performed to obtain a liquid product.

[0025] The acid solution is at least one of nitric acid, sulfuric acid and hydrochloric acid; the concentration of the acid solution is 2-4 mol / L; for example, it can be about 3 mol / L.

[0026] The concentration of the hydrogen peroxide is 30% by mass. The role of hydrogen peroxide is to help reduce the metal, thereby enabling the metal to exist in the mixed aqueous solution in a stable ionic form.

[0027] The volume percentage of the hydrogen peroxide in the acid solution is 5-20%, for example, about 8%, 10%, 15% or about 18%.

[0028] The temperature of the mixed reaction is 25-90° C., for example, about 30° C., 40° C., 50° C., 60° C., 70° C., 80° C. or about 85° C. Within this temperature range, the molecular motion can be accelerated to promote diffusion, which is beneficial to leaching; and the rapid evaporation of the acid solution and hydrogen peroxide during the high temperature process can be avoided, which causes the leaching effect to decrease.

[0029] The duration of the mixed reaction is 1 to 2 hours; for example, it can be about 1.5 hours; within this time range, the metal ions in the solid material can be fully leached, and the leaching time can be saved, the leaching of impurities can be avoided, and the hydrolysis failure of the target metal ions can be avoided. That is, within this range, the leaching efficiency is high, the purity is high, and the production efficiency is high.

[0030] The solid-liquid ratio of the mixed reaction is 1g:20~100mL. For example, it can be about 1g:30mL, 1g:40mL, 1g:50mL, 1g:60mL, 1g:70mL, 1g:80mL or about 1g:90mL. Within this range, sufficient acid can be provided to improve the leaching rate of metal ions in the solid substance, avoiding the waste of acid and the waste of extractant in the subsequent extraction process; it also has good operability and is easy to separate solid and liquid.

[0031] According to some embodiments of the present invention, in the mixed solution, Li +The concentration is ≥ 1350 mg / L. For example, it can be about 1380 mg / L, 1400 mg / L, 1450 mg / L, 1480 mg / L or about 1500 mg / L.

[0032] According to some embodiments of the present invention, in the mixed solution, Ni 2+ The concentration is ≥ 6300 mg / L. For example, it can be about 6350 mg / L, 6360 mg / L or about 6400 mg / L.

[0033] According to some embodiments of the present invention, in the mixed solution, Co 2+ The concentration is ≥ 2350 mg / L. For example, it can be about 2400 mg / L, 2450 mg / L or about 2500 mg / L.

[0034] According to some embodiments of the present invention, in the mixed solution, Mn 2+ The concentration is ≥3300 mg / L. For example, it can be about 3400 mg / L, 4000 mg / L or about 4150 mg / L.

[0035] According to some embodiments of the present invention, step S1 further includes adjusting the pH of the mixed solution to 6-9. For example, it can be about 7, 7.5 or about 8. The pH regulator used is a sodium hydroxide aqueous solution. Specifically, the concentration of the sodium hydroxide aqueous solution is 1.5-2.5 mol / L; for example, it can be about 2 mol / L.

[0036] According to some embodiments of the present invention, in step S1, the remainder of the organic phase A is a diluent.

[0037] According to some embodiments of the present invention, in step S1, the O / A ratio of the organic phase A during extraction is 1:0.2-1.5, for example, about 1:0.5, 1:1 or about 1:1.2.

[0038] When other conditions remain unchanged, when the ratio of organic phase to aqueous phase is greater than 5:1, Cyphos IL 104 has a significant effect on Li + The extraction rate also increases with the increase of organic phase volume. When O / A is less than 2 / 3, the extraction rate of transition metal ions, especially Co 2+ and Mn 2 + The extraction rate of Co 2+ The extraction rate of Mn 2+The extraction rate will be reduced to only 30%. However, it should be noted that the O / A ratio is not a single factor change. If the concentration of metal ions in the mixed solution and the concentration of the extractant in the organic phase A are adjusted within the range provided by the present invention, even if they exceed the above range, a good extraction effect may be obtained.

[0039] According to some embodiments of the present invention, in step S1, the extraction of the organic phase A includes stirring and phase separation in sequence. The stirring time is 8 to 12 minutes, for example, it can be about 10 minutes; the phase separation method includes centrifugation; the phase separation time is 3 to 8 minutes, for example, it can be about 5 minutes.

[0040] According to some embodiments of the present invention, step S1 further includes precipitating lithium from the raffinate phase A.

[0041] The specific operation of lithium deposition is:

[0042] After adjusting the pH of the raffinate phase A, the resulting mixture is reacted with carbonate to precipitate lithium carbonate.

[0043] After adjusting the pH, the pH of the raffinate phase A is 10-12, for example, specifically about 11, and the pH adjuster used is a sodium hydroxide aqueous solution. Specifically, the concentration of the sodium hydroxide aqueous solution is 1.5-2.5 mol / L, for example, specifically about 2 mol / L.

[0044] The carbonate used includes at least one of sodium carbonate and potassium carbonate; for example, it can be sodium carbonate; more specifically, the carbonate is used in the form of a saturated solution thereof.

[0045] The lithium precipitation also includes drying the lithium carbonate.

[0046] According to some embodiments of the present invention, when the mixed solution contains Ni 2+ 、Co 2+ , Mn 2+ When the processing method further comprises the following steps after step S1:

[0047] S2. stripping the loaded organic phase A to obtain a stripping aqueous phase A;

[0048] S3. extracting the stripping aqueous phase A with the organic phase B to obtain a loaded organic phase B and a raffinate phase B;

[0049] The organic phase B includes an extractant P507 (2-ethylhexyl phosphate 2-ethylhexyl ester, 2-ethylhexylhydrogen; molecular formula C 16 H 35 O3P;CAS:14802-03-0);

[0050] The pH of the stripping aqueous phase A is 2-5;

[0051] S4. Extracting the raffinate phase B with the organic phase C to obtain a loaded organic phase C and a raffinate phase C;

[0052] The organic phase C includes an extractant Cyphos IL 104;

[0053] The pH of the raffinate phase B is 1-3.

[0054] The mechanism of the above steps is as follows:

[0055] In step S2, Ni 2+ 、Co 2+ , Mn 2+ Transfer to the stripping aqueous phase A;

[0056] In step S3, Mn 2+ Transferred to the loaded organic phase B, Ni 2+ 、Co 2+ Remain in the raffinate phase B;

[0057] In step S4, Co 2+ Transferred to the loaded organic phase C, Ni 2+ Remains in the raffinate phase C.

[0058] Although the same core extractant is used in step S1 and step S4, the selectivity of the extraction process is different due to the differences in the pH conditions of the aqueous phase and the types of ions contained therein.

[0059] According to some embodiments of the present invention, in step S2, the O / A ratio of the stripping of the loaded organic phase A is 1:0.8-1.2; for example, it can be specifically about 1:1.

[0060] According to some embodiments of the present invention, in step S2, the stripping of the loaded organic phase A includes stirring and mixing and phase separation in sequence. The stirring and mixing time is 8 to 12 minutes; for example, it can be about 10 minutes; the phase separation method includes centrifugation; the phase separation time is 3 to 8 minutes; for example, it can be about 5 minutes.

[0061] According to some embodiments of the present invention, step S3 further includes adjusting the pH of the stripping aqueous phase A to 2-5. For example, it can be about 3, 3.5 or about 4. The pH regulator used is a sodium hydroxide aqueous solution. Specifically, the concentration of the sodium hydroxide aqueous solution is 1.5-2.5 mol / L; for example, it can be about 2 mol / L.

[0062] By controlling the pH of the stripping aqueous phase A, the extractant P507 has an effect on the Mn2+ The extraction rates of the extractant P507 for Mn were all greater than 85% at the optimal volume fraction and pH. The extraction rate of Co 2+ The extraction rates of Ni 2+ No extraction; while pH increased, the extractant P507 had no effect on Co 2+ / Ni 2+ The extraction rate of Mn increases, which is not conducive to 2+ And other transition metal ions separation. Too high pH will also lead to the precipitation of transition metal ions, which is not conducive to extraction.

[0063] According to some embodiments of the present invention, in step S3, the volume fraction of the extractant P507 in the organic phase B is 30% to 90%. For example, it can be about 40%, 50%, 60%, 70% or about 80%. In this concentration range, the extractant P507 can efficiently extract Mn 2+ (extraction rate ≥95%), and Co 2+ / Ni 2+ The extraction rate of Mn 2+ Separated from other transition metal ions.

[0064] According to some embodiments of the present invention, in step S3, the O / A ratio of the organic phase B during extraction is 1 to 3:1. For example, it can be about 2:1. Within this ratio range, Mn 2+ The separation efficiency of extractant P507 is better than that of other transition metal ions. Specifically, when the ratio of organic phase to water is greater than 3, the extraction efficiency of extractant P507 is better than that of other transition metal ions. 2+ The extraction rate of Mn increases with the increase of organic phase volume; when O / A is less than 1, organic phase B has a higher extraction rate of Mn 2+ The extraction rate will also be less than 10%.

[0065] According to some embodiments of the present invention, in step S3, the extraction of the organic phase B includes stirring and mixing and phase separation in sequence. The stirring and mixing time is 8 to 12 minutes; for example, it can be about 10 minutes; the phase separation method includes centrifugation; the phase separation time is 3 to 8 minutes; for example, it can be about 5 minutes.

[0066] According to some embodiments of the present invention, step S3 further comprises stripping the loaded organic phase B to obtain a stripping aqueous phase B, and precipitating manganese from the stripping aqueous phase B. During the stripping process, Mn in the loaded organic phase B 2+ Transfer to the stripping water phase B.

[0067] According to some embodiments of the present invention, the O / A ratio of the back extraction of the loaded organic phase B is 1:0.8-1.2; for example, it can be specifically about 1:1.

[0068] According to some embodiments of the present invention, the stripping of the loaded organic phase B includes stirring and mixing and phase separation in sequence. The stirring and mixing time is 8 to 12 minutes; for example, it can be about 10 minutes; the phase separation method includes centrifugation; the phase separation time is 3 to 8 minutes; for example, it can be about 5 minutes.

[0069] According to some embodiments of the present invention, the manganese precipitation comprises the following steps:

[0070] Adjusting the pH of the stripping aqueous phase B to 7-8; for example, it may be about 7.5;

[0071] Then, the pH-adjusted stripping aqueous phase B is reacted with carbonate to obtain a precipitate, which is then dried to obtain manganese carbonate. The pH adjuster used is a sodium hydroxide aqueous solution. Specifically, the concentration of the sodium hydroxide aqueous solution is 1.5 to 2.5 mol / L; for example, it can be about 2 mol / L.

[0072] The carbonate used includes at least one of sodium carbonate and potassium carbonate; for example, sodium carbonate can be used. In further detail, the carbonate is used in the form of a saturated solution thereof.

[0073] According to some embodiments of the present invention, step S4 further includes adjusting the pH of the raffinate phase B to 1-3. For example, it can be about 1.5, 2 or about 2.5. The pH adjuster used is a sodium hydroxide aqueous solution. Specifically, the concentration of the sodium hydroxide aqueous solution is 1.5-2.5 mol / L; for example, it can be about 2 mol / L. Within this range, the organic phase C has a high affinity for Co 2+ It has high selective extraction ability for Co 2+ The single-stage extraction rate is > 60%, and within this pH range, it is effective for Ni 2+ When the solution pH is greater than 3, although it is effective for Co 2+ The extraction rate of Ni 2+ The extraction capacity of Co increases with the increase of pH, which deteriorates to a certain extent. 2+ with Ni 2+ The separation between.

[0074] According to some embodiments of the present invention, in step S4, the volume fraction of the extractant Cyphos IL 104 in the organic phase C is 10-30%. For example, it can be about 15%, 20% or about 25%. The remainder is a diluent. Within this concentration range, Co 2+ with Ni 2+ Separation between, specifically, Co 2+The extraction rate of Co 2+ The extraction rate of Ni 2+ The extraction rate is less than 10%; if the volume fraction of the extractant Cyphos IL 104 in the organic phase C is lower than the above range, the extraction rate of Co 2+ The extraction rate is reduced. If we want to achieve the same 2+ The separation of Co requires more extraction stages, which increases the length and difficulty of the operation process; on the contrary, if the volume fraction is greater than the above range, 2+ with Ni 2+ The separation efficiency between them decreased to a certain extent.

[0075] According to some embodiments of the present invention, in step S4, the O / A ratio of the organic phase C during extraction is 1:1.5-2. For example, it may be about 1:1.8.

[0076] According to some embodiments of the present invention, in step S4, the extraction of the organic phase C has a level of 1 to 5. For example, it can be specifically 3 or 4. Within this range, Co 2+ with Ni 2+ The separation efficiency between Co 2+ extraction efficiency.

[0077] According to some embodiments of the present invention, in step S4, the extraction of the organic phase C includes stirring and mixing and phase separation in sequence. The stirring and mixing time is 8 to 12 minutes; for example, it can be about 10 minutes; the phase separation method includes centrifugation; the phase separation time is 3 to 8 minutes; for example, it can be about 5 minutes.

[0078] According to some embodiments of the present invention, step S4 further includes precipitating nickel from the raffinate phase C.

[0079] According to some embodiments of the present invention, the step of depositing nickel is:

[0080] Adjusting the pH of the raffinate phase C to 8-10; for example, it may be about 9;

[0081] After that, the pH-adjusted raffinate phase C is reacted with carbonate to obtain a precipitate, which is then dried to obtain nickel carbonate (light green). The pH adjuster used is a sodium hydroxide aqueous solution. Specifically, the concentration of the sodium hydroxide aqueous solution is 1.5-2.5 mol / L; for example, it can be about 2 mol / L.

[0082] The carbonate used includes at least one of sodium carbonate and potassium carbonate; for example, sodium carbonate can be used. In further detail, the carbonate is used in the form of a saturated solution thereof.

[0083] According to some embodiments of the present invention, step S4 further comprises stripping the loaded organic phase C to obtain a stripping aqueous phase C, and precipitating cobalt from the stripping aqueous phase C. Thus, the Co in the loaded organic phase C 2+ Transfer to the stripping aqueous phase C.

[0084] According to some embodiments of the present invention, the O / A ratio of the stripping of the loaded organic phase C is 1:0.8-1.2; for example, it can be specifically about 1:1.

[0085] According to some embodiments of the present invention, the stripping of the loaded organic phase C includes stirring and mixing and phase separation in sequence. The stirring and mixing time is 8 to 12 minutes; for example, it can be about 10 minutes; the phase separation method includes centrifugation; the phase separation time is 3 to 8 minutes; for example, it can be about 5 minutes.

[0086] According to some embodiments of the present invention, the cobalt precipitation comprises the following steps:

[0087] Adjusting the pH of the stripping aqueous phase C to 10-12; for example, it may be about 11;

[0088] The pH-adjusted stripping aqueous phase C is reacted with a base, and the resulting precipitate is dried to obtain cobalt hydroxide (rose red).

[0089] The pH regulator used is a sodium hydroxide aqueous solution. Specifically, the concentration of the sodium hydroxide aqueous solution is 1.5-2.5 mol / L; for example, it can be about 2 mol / L.

[0090] The alkali used includes at least one of sodium hydroxide and potassium hydroxide; for example, it can be sodium hydroxide; more specifically, it can be used in the form of a saturated sodium hydroxide aqueous solution.

[0091] Unless otherwise specified, the diluent included in the organic phase used in the present invention is kerosene, thereby improving the physical properties of the corresponding organic phase, especially adjusting the viscosity and density, increasing the fluidity, and expanding the density difference between the organic phase and the aqueous phase, which is beneficial to the separation and clarification of the two phases.

[0092] If not otherwise specified, the stripping agent used in the stripping of the present invention is an acid aqueous solution, wherein the solute is at least one of HCl, H2SO4 or HNO3; and the concentration is 1-3 mol / L.

[0093] According to the above description, the treatment method provided by the present invention can recover Li / Co / Mn / Ni in the mixed solution respectively to obtain Li2CO3, Co(OH)2, MnCO3 and NiCO3 with high economic added value; and the recovery rate of the target metal ions is >95%. In addition, the treatment method provided by the present invention also has the advantages of high extraction rate, strong selectivity, simple and stable process, safety and reliability (the operation process is at normal pressure and the temperature is ≤100°C), the extractant can be recycled, low cost, easy operation, etc. Especially for the recovery of positive electrode materials of ternary lithium batteries, the effect is excellent.

[0094] According to an embodiment of the second aspect of the present invention, there is provided an application of the treatment method described in an embodiment of the first aspect of the present invention in waste lithium battery recycling, hydrometallurgy and transition metal catalyst recycling.

[0095] Since the application adopts all the technical solutions of the mixed solution processing method of the above embodiment, it at least has all the beneficial effects brought by the technical solutions of the above embodiment.

[0096] If there is no special explanation, the actual meaning of “about” in the present invention is that the error is allowed to be within the range of ±2%, for example, about 100 is actually 100±2%×100.

[0097] Unless otherwise specified, “between” in the present invention includes the number itself, for example, “between 2 and 3” includes the endpoint values ​​2 and 3.

[0098] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0099] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0100] Figure 1 It is a schematic diagram of the operation flow of an embodiment of the present invention. DETAILED DESCRIPTION

[0101] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0102] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0103] Example 1

[0104] refer to Figure 1 This example provides a method for treating a mixed solution, and the specific steps of the method are:

[0105] S0. Mixed solution acquisition:

[0106] Take 2g of powder of waste lithium battery positive electrode material (composition see Table 1) in a three-necked flask, add 100mL of a mixed aqueous solution of acid and hydrogen peroxide; the acid is 4 mol / L HCl, the concentration of hydrogen peroxide is 30wt%; the volume ratio of acid to hydrogen peroxide is 5:100.

[0107] Table 1 Composition and content of the waste lithium battery positive electrode material used in Example 1

[0108]

[0109] The obtained mixture was heated in a constant temperature water bath at 85°C for 1 h for leaching, and a mixed solution was obtained after solid-liquid separation. The parameters of the mixed solution obtained in this example are shown in Table 2.

[0110] Table 2 Partial parameters of the mixed solution obtained in step S0 of Example 1

[0111]

[0112] S1. Take 10 mL of the mixed solution obtained in step S0, adjust its pH to 7.5 with 2 mol / L NaOH, and place it in a centrifuge tube, add 10 mL of organic phase A, the organic phase A contains 60% volume fraction of extractant Cyphos IL 104 and 40% volume fraction of diluent kerosene; stir magnetically for 10 min at room temperature to mix, after mixing, place the centrifuge tube in a centrifuge for 5 min, take it out, separate the organic phase and the aqueous phase, and obtain a loaded organic phase A containing Co / Mn / Ni and a raffinate phase A containing Li;

[0113] Take 10 mL of raffinate phase A, adjust the pH of the aqueous phase to 11 with 2 mol / L NaOH, add saturated Na2CO3 solution and stir for precipitation, filter and dry after stirring to obtain white Li2CO3 powder;

[0114] S2. Stripping of the loaded organic phase A: 10 mL of 3 mol / L H2SO4 aqueous solution was taken to strip the loaded organic phase A; specifically, the two were mixed by magnetic stirring at room temperature for 10 min, and then the resulting mixture was placed in a centrifuge and centrifuged for 5 min and then taken out, and the organic phase and the aqueous phase were separated to obtain a stripping aqueous phase A containing Mn / Co / Ni;

[0115] S3. Extraction of manganese: Take 10 mL of the stripping aqueous phase A, adjust the pH to 4 with 2 mol / L NaOH, and place it in a centrifuge tube, add 10 mL of the organic phase B, the organic phase B contains 70% by volume of the extractant P507, and the remainder is the diluent kerosene; stir the two for 10 minutes by magnetic stirring to mix, and place the resulting mixture in a centrifuge for 5 minutes and then take it out, separate the organic phase and the aqueous phase, and obtain the raffinate phase B containing Co / Ni and the loaded organic phase B containing Mn;

[0116] Stripping of manganese: 10 mL of 2 mol / L H2SO4 and the loaded organic phase B were mixed under magnetic stirring at room temperature for 10 min, and the resulting mixture was centrifuged in a centrifuge for 5 min and then taken out, and the organic phase and the aqueous phase were separated to obtain the stripping aqueous phase B containing Mn;

[0117] Manganese precipitation: Take 10mL of stripping aqueous phase B, adjust the pH of the aqueous phase to 7.5 with 2mol / L NaOH, add saturated Na2CO3 solution and stir for precipitation, then filter and dry after stirring to obtain pink-white MnCO3 powder;

[0118] S4. Extraction of cobalt: Take 10 mL of raffinate phase B, adjust the pH to 2.5 with 2 mol / L NaOH, and place in a centrifuge tube, add 5 mL of organic phase C; the organic phase C contains 15% by volume of the extractant Cyphos IL 104; the remainder is the diluent kerosene; the two are mixed by magnetic stirring at room temperature for 10 min, and the resulting mixture is placed in a centrifuge for centrifugation for 5 min and then taken out, the organic phase and the aqueous phase are separated, and the raffinate phase C containing Ni and the loaded organic phase C containing Co are obtained;

[0119] Stripping of cobalt: 10 mL of 3 mol / L H2SO4 was added to the loaded organic phase C, and the mixture was mixed by magnetic stirring for 10 min at room temperature. The obtained mixture was centrifuged in a centrifuge for 5 min and then taken out, and the organic phase and the aqueous phase were separated to obtain the stripping aqueous phase C containing Co;

[0120] Cobalt precipitation: Take 10 mL of the stripping aqueous phase C, adjust the pH of the aqueous phase to 11 with 2 mol / L NaOH, and add a saturated NaOH solution and stir to precipitate. After stirring, filter and dry to obtain rose-red Co(OH)2 powder;

[0121] Nickel precipitation: Take 10 mL of the raffinate phase C, adjust the pH of the aqueous phase to 9 with 2 mol / L NaOH, add a saturated Na2CO3 solution and stir for 1 h at room temperature for precipitation. After stirring, filter and dry to obtain a light green NiCO3 powder.

[0122] In this example, steps S1 to S4 are only for the convenience of expression and do not absolutely represent the order of the steps. For example, the stripping and precipitation of manganese in step S3 can be performed at any time period after the extraction of manganese.

[0123] In this example, the amount of solution and other materials used is only for the convenience of description and determination of proportions. In actual production, it can be expanded proportionally as needed.

[0124] In this example, unless otherwise specified, the feed amount of the same material is the total amount of the material obtained in the previous step.

[0125] Example 2

[0126] This example provides a method for treating a mixed solution, which is different from Example 1 in that:

[0127] The operation of step S0 is different, specifically:

[0128] S0. Take 2g of waste lithium battery positive electrode material powder (see Table 3) in a three-necked flask, add 100mL of a mixed aqueous solution of acid and hydrogen peroxide, wherein the acid is 2mol / L H2SO4; the concentration of hydrogen peroxide is 30wt%; the volume ratio of acid to hydrogen peroxide is 10:100; stir and heat the obtained mixture in a constant temperature water bath at 85℃ for 1h to leaching, and obtain a mixed solution after solid-liquid separation. Some components in the mixed solution are shown in Table 4.

[0129] Table 3 Composition and content of waste lithium battery positive electrode material powder used in Example 2

[0130]

[0131] Table 4 Partial parameters of the mixed solution obtained in step S0 of Example 2

[0132]

[0133] Example 3

[0134] This example provides a method for treating a mixed solution, which is different from Example 1 in that:

[0135] In step S1, the volume percentage of the extractant Cyphos IL 104 in the organic phase A is 80%; the remainder is the diluent kerosene.

[0136] Example 4

[0137] This example provides a method for treating a mixed solution, which is different from Example 1 in that:

[0138] In step S3, the pH of the stripping aqueous phase A is adjusted to 3.

[0139] Example 5

[0140] This example provides a method for treating a mixed solution, which is different from Example 1 in that:

[0141] In step S4, the pH of the raffinate phase B is adjusted to 1.

[0142] Comparative Example 1

[0143] This example provides a method for treating a mixed aqueous solution, which is different from Example 1 in that:

[0144] In step S1, the volume percentage of the extractant Cyphos IL 104 in the organic phase A is 10%; the remainder is the diluent kerosene.

[0145] Comparative Example 2

[0146] This example provides a method for treating a mixed aqueous solution, which is different from Example 1 in that:

[0147] In step S3, the pH of the stripping aqueous phase A is adjusted to 7.

[0148] Comparative Example 3

[0149] This example provides a method for treating a mixed aqueous solution, which is different from Example 1 in that:

[0150] In step S1, the organic phase A is a mixture of 6 mL of P350 (CAS: 222.261581) extractant and 4 mL of kerosene.

[0151] Comparative Example 4

[0152] This example provides a method for treating a mixed solution, which is different from Example 1 in that:

[0153] In step S1, the pH of the mixed solution is adjusted to 4.

[0154] Test Case

[0155] This example tests the extraction efficiency of Li, Co, Mn and Ni in the embodiment and comparative example step S1, as well as the mass and purity of the final lithium carbonate, manganese carbonate, nickel carbonate and cobalt hydroxide; and calculates the yield of lithium, nickel, cobalt and manganese. The purity test method is to dissolve the corresponding solid product, use ICP-OES to test the concentration of lithium, nickel, cobalt or manganese therein, and calculate the ratio of the concentration to the theoretical concentration, which is the purity (the purity of the corresponding compound). The yield is exemplified as follows: The yield of lithium is the ratio of the content of lithium in lithium carbonate to that in the mixed solution. The above results are rounded to one decimal place.

[0156] The test results of the above items are shown in Table 5.

[0157] Table 5 Test results of embodiments and comparative examples

[0158]

[0159] By comparing the results of the embodiments and the comparative examples, it can be seen that within the scope provided by the present invention, by changing the concentration of the extractant in the organic phase A, the pH of the mixed solution, the process of obtaining the mixed solution, and even the conditions of the subsequent extraction step, a product with higher purity can be obtained, and the yield of the corresponding metal is higher; specifically, the purity of lithium carbonate is ≥99.5%; the yield of lithium is ≥99.5%, and can reach 99.7% or even 99.8% in actual production; the purity of cobalt hydroxide is ≥97.5%, and can reach 97.8% or even 97.8% in actual production. 8.0%; the yield of cobalt is ≥98.0%, which can reach 98.0%, 98.3% or even 98.5% in actual production; the purity of manganese carbonate is ≥97.5%, which can reach 97.5% or even 98.0% in actual production; the yield of manganese is ≥98.5%, which can reach 98.5%, 99.0% or even 99.5% in actual production; the purity of nickel carbonate is ≥99.0%, which can reach 99.5% in actual production; the yield of nickel is ≥96.5%, which can reach 97.0% or even 97.5% in actual production.

[0160] By comparing Example 1 with Comparative Example 1, it can be seen that if the proportion of the extractant Cyphos IL 104 in the organic phase A is not within the range required by the present invention, in the extraction of step S1, the extraction ratio of transition metals decreases, and the extraction ratio of Co 2+ The extraction performance is greatly reduced, especially Ni 2+ , it has almost no extraction performance and cannot separate the transition metal elements and Li from the mixed solution, resulting in the subsequent inability to separate the transition metals one by one normally, and the purity of the corresponding metal compounds also decreases.

[0161] By comparing Example 1 and Comparative Example 2, it can be seen that if the pH adjustment in step S3 is not within the range required by the present invention, it will basically not affect the separation of transition metals and lithium, that is, it will basically have no significant effect on the yield and purity of lithium; however, it will cause Mn 2+ With Co 2+ 、Ni 2+ The co-extraction of manganese and cobalt and nickel significantly affects the separation of manganese and cobalt.

[0162] By comparing Example 1 and Comparative Example 3, it can be seen that if the extractant CyphosIL 104 in the organic phase A in step S1 of the present invention is replaced with a common nickel-cobalt extractant, the resulting effect trend is similar to that of Comparative Example 1. On the one hand, the separation of lithium and transition metals cannot be achieved, and on the other hand, the separation of nickel, cobalt and manganese cannot be effectively achieved in the subsequent stripping and re-extraction.

[0163] It can also be seen from the processes of the embodiments and comparative examples that in the method provided by the present invention, the implementation temperature of all procedures is less than 100° C., and the process is safe, reliable and highly stable.

[0164] It is known to those skilled in the art that the same extractant has different selectivity for different metal ions, and the same extractant may not play the same role in different organic phases-aqueous phases. In the method provided by the present invention, through the design of steps and parameters, the extractant that cannot be used for extracting transition metal ions in traditional technology is creatively used for the co-extraction of transition metal ions in a mixed solution; the separate recovery of Li / Co / Mn / Ni is achieved, and the purity of the recovered products is high; in addition, the treatment method provided by the present invention is simple to operate, safe and reliable, and is expected to be widely used in hydrometallurgy, especially in the recovery of waste lithium-ion batteries.

[0165] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A method for treating a mixed solution, wherein the mixed solution contains Ni 2+ 、Co 2+ , Mn 2+ At least one of + ; It is characterized in that, The processing method comprises the following steps: S1. Extracting the mixed solution with an organic phase A to obtain a loaded organic phase A and a raffinate phase A; The organic phase A comprises the extractant Cyphos IL 104; In the organic phase A, the volume fraction of the extractant Cyphos IL 104 is 30% to 100%; The pH of the mixed solution is 6-9.

2. The processing method according to claim 1, characterized in that: The organic phase A is extracted with an O / A ratio of 1:0.2-1.5; step S1 also includes precipitating lithium from the raffinate phase A.

3. The processing method according to claim 1, characterized in that: The mixed solution is a leachate of a solid substance; the solid substance comprises at least one of a lithium battery positive electrode material, a transition metal catalyst and a transition metal mineral.

4. The processing method according to any one of claims 1 to 3, characterized in that: When the mixed solution contains Ni 2+ 、Co 2+ , Mn 2+ When the processing method further comprises the following steps after step S1: S2. stripping the loaded organic phase A to obtain a stripping aqueous phase A; S3. extracting the stripping aqueous phase A with the organic phase B to obtain a loaded organic phase B and a raffinate phase B; The organic phase B includes an extractant P507; The pH of the stripping aqueous phase A is 2-5; S4. Extracting the raffinate phase B with the organic phase C to obtain a loaded organic phase C and a raffinate phase C; The organic phase C includes an extractant Cyphos IL 104; The pH of the raffinate phase B is 1-3.

5. The processing method according to claim 4, characterized in that: Step S3 further includes stripping the loaded organic phase B to obtain a stripping aqueous phase B, and precipitating manganese from the stripping aqueous phase B.

6. The processing method according to claim 4, characterized in that: In step S3, the organic phase B is extracted with an O / A ratio of 1 to 3:

1.

7. The processing method according to claim 4, characterized in that: Step S4 also includes precipitating nickel from the raffinate phase C.

8. The processing method according to claim 4, characterized in that: Step S4 also includes stripping the loaded organic phase C to obtain a stripping aqueous phase C, and precipitating cobalt from the stripping aqueous phase C.

9. The processing method according to claim 4, characterized in that: In step S4, the organic phase C is extracted with an O / A ratio of 1:1.5-2.

10. Application of the treatment method according to any one of claims 1 to 9 in waste lithium battery recovery, hydrometallurgy and transition metal catalyst recovery.

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