Impurity removal method for ternary black powder leachate

Abstract

The invention provides an impurity removal method for ternary black powder leachate. The impurity removal method comprises the following steps: adjusting the pH value of the ternary black powder leaching solution to a target value by adopting a calcium reagent, and carrying out primary impurity removal to obtain an iron and aluminum removed leaching solution; mixing the iron-removed and aluminum-removed leaching solution with fluoride, and performing secondary impurity removal to obtain a calcium-removed and magnesium-removed leaching solution; and acidifying and extracting the calcium and magnesium removed leaching solution to remove fluorine to obtain a ternary impurity removal solution. According to the process, introduction of the sodium element is avoided, the purpose of removing iron, aluminum, calcium, magnesium and fluorine in the ternary black powder leaching solution is achieved, the fluorine concentration in the ternary impurity removal solution is reduced to 200 mg / L or below, the excellent fluorine removal effect is shown, and the process has the advantages of being easy to operate, simple in equipment and low in cost. In addition, the impurity removal method prevents a finished product purified in a subsequent extraction section from containing sodium impurities which are difficult to remove, and only a semi-extraction process is needed for purification in the extraction section, so that the alkali consumption of the extraction section is greatly reduced, and the method has an important application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of battery recycling, and particularly relates to a method for removing impurities from a ternary black powder leachate. Background Art

[0002] With the rapid development of new energy vehicles, an increasing number of used power batteries are being retired and scrapped, with nickel-cobalt-manganese (NiCoMn) lithium-ion batteries accounting for a significant portion. After discharging, disassembling, crushing, and screening these batteries, the resulting black mixture is called NiCoMn black powder. This powder contains significant amounts of valuable metals, including nickel, cobalt, manganese, and lithium. The main elements include Ni, Co, Mn, Li, Al, Cu, and F.

[0003] In the prior art, the recovery of valuable metals in ternary black powder mostly adopts wet recovery, usually using sulfuric acid and a reducing agent for reduction leaching to obtain a leachate (hereinafter referred to as ternary leachate). In order to reduce the iron and aluminum content in the ternary leachate, calcium hydroxide is often used to remove iron and aluminum. However, this process will introduce calcium ions. In order to remove calcium and magnesium impurities, a large amount of fluorine needs to be introduced, which will lead to a high fluorine content in the feed solution (>4g / L). Due to the pH of the ternary leachate (pH<7) and the nickel, cobalt and manganese content (>100g / L), the high-fluorine ternary liquid is difficult to remove by precipitation or resin adsorption.

[0004] To this end, researchers have conducted research. For example, CN119040634A discloses a method for removing fluorine and heavy lithium from a high-fluorine battery black powder leachate. The specific steps are as follows: (1) reacting ternary black powder with a sulfuric acid leaching agent, adjusting the pH at the reaction endpoint, and separating the solid and liquid after the reaction to obtain a high-fluorine leachate and a leach residue; (2) adjusting the pH of the high-fluorine leachate with an alkaline reagent to remove Al and F, filtering to obtain an aluminum-fluoride-removed leachate and aluminum-fluoride residue, and washing the aluminum-fluoride residue and the leach residue in step (1) with water respectively; (3) passing the aluminum-fluoride-removed leachate into a The defluorination resin is subjected to defluorination to obtain a resin defluorination leachate; (4) an alkaline reagent is added to adjust the pH of the resin defluorination leachate to recover Ni, Co, and Mn therein, and the lithium extraction liquid and nickel-cobalt-manganese slag are filtered; (5) the nickel-cobalt-manganese slag is washed with water to obtain a nickel-cobalt-manganese washed slag, the nickel-cobalt-manganese washed slag and the leaching slag washed slag are mixed in proportion and fed into a nickel-cobalt-manganese leaching-extraction system to remove impurities and separate nickel, cobalt, and manganese; (6) the lithium extraction liquid is fed into a calcium-magnesium removal resin for deep impurity removal to obtain a refined lithium hydroxide solution, and sodium carbonate is added to the refined lithium hydroxide solution to precipitate lithium for the preparation of lithium carbonate. Patent CN116565367A discloses a method for extract-free regeneration of battery materials, comprising the following steps: 1) hydrolyzing and removing impurities from a battery black powder leachate to obtain a hydrolysis-removed impurity solution; 2) using fluoride to remove calcium and magnesium ions from the hydrolysis-removed impurity solution of step (1) to obtain a calcium- and magnesium-removed solution; 3) defluoridating the calcium- and magnesium-removed solution of step (2) to obtain a nickel-cobalt-manganese solution, which is then used for precursor synthesis to obtain a nickel-cobalt-manganese precursor material. The defluoridation in step (3) is performed using an ion exchange resin.

[0005] It can be seen that although the above-mentioned improvement measures have improved the removal effect of impurity fluorine to a certain extent, the effect needs to be further optimized. In addition, the sodium element is introduced into the process flow. Since the sodium element is difficult to remove, the difficulty of impurity removal is increased, which is easy to affect the extraction effect of subsequent extraction steps, reduce product purity, and affect product performance.

[0006] In addition, in the existing technology, after removing iron and aluminum, a full extraction process is carried out for purification. This method has high alkali consumption, and the finished product after extraction and purification contains sodium impurities that are difficult to remove, which affects the purity and quality of the product, increases the production cost of the product, and leads to poor market application prospects of the product.

[0007] Therefore, there is an urgent need to provide a method for removing impurities to solve the problem that sodium is introduced into the ternary black powder leachate during the impurity removal process and the fluorine content is high after impurity removal. Summary of the Invention

[0008] In view of the deficiencies in the prior art, the object of the present invention is to provide a method for removing impurities from a ternary black powder leachate. The present invention first utilizes a calcium reagent to remove iron and aluminum, then adds fluoride to remove calcium and magnesium, and finally performs acidification and extraction for defluorination. This process not only avoids the introduction of sodium elements throughout the entire process, thereby achieving the purpose of removing iron, aluminum, calcium, magnesium, and fluorine from the ternary black powder leachate, but also converts the fluorine element into the form of hydrofluoric acid during the acidification process, so as to achieve efficient removal during the extraction and defluorination process, thereby reducing the fluorine concentration in the ternary impurity removal liquid to below 200 mg / L, showing an excellent defluorination effect. The process has the advantages of simple operation, simple equipment, and low cost. In addition, this impurity removal method prevents the finished product from containing difficult-to-remove sodium impurities after purification in the subsequent extraction section, and the extraction section only needs to undergo a semi-extraction process for purification, which greatly reduces the alkali consumption in the extraction section and has important application prospects.

[0009] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0010] The present invention provides a method for removing impurities from a ternary black powder leachate, the method comprising the following steps:

[0011] The pH of the ternary black powder leachate is adjusted to the target value using a calcium reagent, and a primary impurity removal is performed to obtain an iron and aluminum-removed leachate.

[0012] The iron and aluminum removal leachate is mixed with fluoride and subjected to secondary impurity removal to obtain a calcium and magnesium removal leachate.

[0013] The calcium and magnesium removal leachate is acidified and extracted to remove fluorine to obtain a ternary impurity removal liquid.

[0014] The present invention first uses a calcium reagent to remove iron and aluminum, then adds fluoride to remove calcium and magnesium, and finally performs acidification and extraction to remove fluorine. This process not only avoids the introduction of sodium elements throughout the entire process, achieving the purpose of removing iron, aluminum, calcium, magnesium and fluorine in the ternary black powder leachate, but also converts the fluorine element into the form of hydrofluoric acid during the acidification process, so as to achieve efficient removal during the extraction and defluorination process, so that the fluorine concentration in the ternary impurity removal liquid is reduced to below 200 mg / L, showing an excellent defluorination effect. The process has the advantages of simple operation, simple equipment and low cost. In addition, this impurity removal method prevents the subsequent extraction stage from containing difficult-to-remove sodium impurities in the finished product after purification, and the extraction stage only needs to be purified by a semi-extraction process, which greatly reduces the alkali consumption of the extraction stage and has important application prospects.

[0015] In the present invention, acidification is used to convert the fluorine element in the leachate into hydrofluoric acid, so that the existence form of the fluoride ions is simplified, which is beneficial to improving the selectivity of the extractant for fluoride ions. Compared with directly extracting the fluorine element in the leachate, the extractant can react with the fluoride ions in the hydrofluoric acid more efficiently, reducing the interference of other impurity ions on the extraction process, thereby improving the extraction efficiency and the fluoride removal effect, and removing fluoride more thoroughly. By first converting into hydrofluoric acid and then extracting and removing fluoride, some impurities can be removed or reduced through the early conversion process, making the extraction system relatively simple, thereby reducing the possibility of impurity entrainment.

[0016] Preferably, the steps of preparing the ternary black powder leachate include:

[0017] The ternary black powder, acid solution and reducing agent are mixed and reduction leaching is performed to obtain the ternary black powder leachate.

[0018] Preferably, the acid solution comprises sulfuric acid.

[0019] Preferably, the reducing agent comprises hydrogen peroxide.

[0020] In the reduction leaching process of the ternary black powder, the present invention uses hydrogen peroxide as a reducing agent, which has the following advantages: 1) it can provide strong reducing ability and effectively leach metal elements such as nickel, cobalt, and manganese in the ternary black powder into the solution in the form of ions; 2) hydrogen peroxide has oxidizing properties and oxidizes the reduced ferrous iron into easily precipitated trivalent iron in an acidic solution, which can be directly removed by adjusting the pH without adding other oxidants; and 3) hydrogen peroxide generates water after being reduced, without introducing new impurity ions, and is environmentally friendly.

[0021] Preferably, the reduction leaching temperature is 60-90°C, for example, 60°C, 70°C, 80°C or 90°C.

[0022] Preferably, the reduction leaching time is 2-6 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours.

[0023] Preferably, the impurity ions in the ternary black powder leachate include calcium ions, magnesium ions, iron ions, aluminum ions and fluoride ions.

[0024] It should be noted that the valuable metals in the ternary black powder leachate include nickel ions, cobalt ions and manganese ions.

[0025] Preferably, the concentration of fluoride ions in the ternary black powder leachate is greater than 4 g / L, for example, it may be 4.5 g / L, 5 g / L or 5.5 g / L.

[0026] Preferably, the calcium reagent includes any one or a combination of at least two of calcium hydroxide slurry, calcium oxide or calcium carbonate, preferably calcium hydroxide slurry.

[0027] The present invention adopts calcium hydroxide slurry as a calcium reagent in the process of removing iron and aluminum, which can dissociate hydroxide ions in the solution and react with iron and aluminum ions to form precipitates. The reaction rate is relatively fast. In addition, the addition of calcium hydroxide can improve the filtration performance of the filter residue, thereby increasing the filter press rate.

[0028] Preferably, the target value is 4.5-5, for example, it can be 4.5, 4.6, 4.7, 4.8, 4.9 or 5.

[0029] Preferably, the temperature of the primary impurity removal is 60-90°C, for example, 60°C, 70°C, 80°C or 90°C.

[0030] Preferably, the time for the primary impurity removal is 1.5-3 hours, for example, 1.5 hours, 2 hours, 2.5 hours or 3 hours.

[0031] Preferably, the primary impurity removal process is accompanied by stirring.

[0032] Preferably, the fluoride is manganese fluoride.

[0033] Preferably, the amount of fluoride added is 3.5-5 times the theoretical amount, for example, 3.5 times, 4 times, 4.5 times or 5 times.

[0034] It should be noted that the amount of fluoride added is 3.5-5 times the theoretical amount, that is, the ratio of the total molar amount of Ca and Mg in the iron and aluminum removal leachate to the molar amount of F in the fluoride is 1:(7-10), for example, it can be 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5 or 1:10, etc.

[0035] In the present invention, an appropriate amount of fluoride is added to allow calcium and magnesium ions to fully react with fluoride ions to form insoluble calcium fluoride and magnesium fluoride precipitates. Excessive fluoride may result in excessive fluoride ion concentration in the solution, requiring additional steps to remove the excess fluoride, increasing process complexity and cost. Therefore, an appropriate amount of fluoride is added to ensure effective calcium and magnesium removal while minimizing the risk of impurity introduction.

[0036] Preferably, the temperature of the secondary impurity removal is 20-60°C, for example, 20°C, 30°C, 40°C, 50°C or 60°C.

[0037] Preferably, the time for the secondary impurity removal is 2-4 hours, for example, 2 hours, 3 hours or 4 hours.

[0038] Preferably, the secondary impurity removal process is accompanied by stirring.

[0039] Preferably, the acidifying agent used in the acidification process includes concentrated sulfuric acid. The present invention does not limit the mass fraction of concentrated sulfuric acid, and it is considered concentrated sulfuric acid if it is greater than or equal to 70%. For example, it can be 70%, 75%, 80% or 85%.

[0040] In this invention, concentrated sulfuric acid is used as the acidifying agent. The strong acidity of concentrated sulfuric acid can disrupt the solubility equilibrium of fluoride ions, driving the reaction toward the formation of HF, ensuring the most complete conversion of fluoride ions and improving fluoride removal efficiency. In contrast, if hydrochloric acid is used for acidification, it will introduce Cl-, which may interfere with subsequent extraction and precipitation processes (for example, chloride ions may corrode equipment or affect metal ion separation).

[0041] Preferably, the mass volume ratio of the concentrated sulfuric acid to the calcium and magnesium removal leachate is 20-80 g / L, for example, it can be 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L or 80 g / L.

[0042] In the present invention, the appropriate amount of concentrated sulfuric acid added is conducive to the formation of HF and improves the extraction rate.

[0043] It should be noted that 20-80 g / L refers to the mass of concentrated sulfuric acid added to every 1 L of calcium and magnesium removal leachate.

[0044] Preferably, the acidification temperature is room temperature, for example, it can be in the range of 20-30°C, such as 20°C, 25°C or 30°C.

[0045] Preferably, the acidification time is 0.5-1 h, for example, 0.5 h, 0.8 h or 1 h.

[0046] Preferably, the acidification process is accompanied by stirring.

[0047] Preferably, the extraction and defluorination method includes multi-stage countercurrent extraction.

[0048] In the present invention, multi-stage countercurrent extraction enables fluoride ions in the aqueous phase to contact the extractant in the organic phase in reverse direction in each stage through step-by-step mass transfer, and each stage can achieve the distribution of fluoride ions from the aqueous phase to the organic phase.

[0049] Preferably, the number of stages of the multi-stage countercurrent extraction is greater than or equal to 5, for example, it can be 5, 6, 7 or 8 stages.

[0050] In the present invention, the number of stages of multi-stage countercurrent extraction is greater than or equal to 5, and the balance is broken by the cascade effect, so that the organic phase is always in contact with the aqueous phase during the countercurrent process, the extraction capacity of the organic phase is fully utilized, a better extraction effect is achieved, and the residual concentration of fluoride ions in the aqueous phase is greatly reduced.

[0051] Preferably, in the process of extractive defluorination, the extractant used includes TBP (tributyl phosphate).

[0052] In the present invention, tributyl phosphate (TBP) is a neutral phosphorus extractant with excellent performance. In the hydrometallurgy of rare earth ores, TBP is commonly used to extract light rare earth elements (such as lanthanum, cerium, praseodymium, and neodymium) from sulfuric acid or hydrochloric acid systems, achieving step-by-step separation of different rare earth elements by controlling the acidity. In the recycling of ternary lithium batteries, TBP is commonly used to recover and purify uranium and other metals (such as nickel, cobalt, and manganese). The present application uses TBP as an extractant for fluorine removal, that is, HF removal, which can extract fluoride ions into the organic phase in the form of hydrofluoric acid molecules, thereby achieving fluorine removal capabilities.

[0053] Preferably, during the extraction and defluorination process, an auxiliary extractant is also added, and the auxiliary extractant includes TOA (trioctylamine).

[0054] Preferably, a diluent is added during the extraction and defluorination process, and the diluent includes kerosene.

[0055] It should be noted that, in the prior art, TBP is often used in combination with kerosene for lithium extraction, while the present application utilizes TBP in combination with kerosene to remove higher concentrations of fluoride ions in the ternary black powder leachate.

[0056] Preferably, in the process of extraction and defluorination, the organic phase includes an extractant and a diluent, and the volume ratio of the extractant to the diluent is (4-8):(2-6), wherein the selection range of the extractant "4-8" can be, for example, 4, 5, 6, 7 or 8, and the selection range of the diluent "2-6" can be, for example, 2, 3, 4, 5 or 6, etc.

[0057] Preferably, in the ternary impurity removal liquid, the concentrations of calcium ions, magnesium ions, iron ions and aluminum ions are each independently less than 5 mg / L, for example, they can be 4.5 mg / L, 4 mg / L, 3 mg / L, 2 mg / L, 1 mg / L or 0.1 mg / L, etc., and the concentration of fluoride ions is less than 200 mg / L, for example, they can be 180 mg / L, 150 mg / L, 120 mg / L, 100 mg / L, 80 mg / L or 50 mg / L, etc.

[0058] Preferably, the preparation method comprises the following steps:

[0059] (1) crushing and disassembling the waste batteries and screening them to obtain ternary black powder;

[0060] The ternary black powder, acid solution and hydrogen peroxide are mixed and subjected to reduction leaching at 60-90° C. for 2-6 hours to obtain a ternary black powder leachate; wherein the impurity ions in the ternary black powder leachate include calcium ions, magnesium ions, iron ions, aluminum ions and fluoride ions, and the concentration of fluoride ions is greater than 4 g / L.

[0061] (2) Using a calcium reagent to adjust the pH of the ternary black powder leachate to 4.5-5, and performing a primary impurity removal at 60-90° C. for 1.5-3 hours, with stirring during the primary impurity removal process. After the primary impurity removal is completed, solid-liquid separation is performed to obtain an iron-aluminum-removed leachate.

[0062] (3) The iron and aluminum removal leachate and fluoride are mixed, and secondary impurity removal is performed at 20-60° C. for 2-4 hours, accompanied by stirring during the secondary impurity removal process. After the secondary impurity removal is completed, solid-liquid separation is performed to obtain a calcium and magnesium removal leachate; wherein the amount of fluoride added is 3.5-5 times the theoretical amount.

[0063] (4) under stirring conditions, adding concentrated sulfuric acid to the decalcified magnesium leachate for acidification to obtain an acidified feed solution; wherein the mass volume ratio of concentrated sulfuric acid to the decalcified magnesium leachate is 20-80 g / L, the acidification temperature is room temperature, the acidification time is 0.5-1 h, and the acidified feed solution contains hydrofluoric acid.

[0064] (5) Under the condition of 20-60°C (for example, 20°C, 30°C, 40°C, 50°C or 60°C, etc.), the acidified liquid is subjected to multi-stage countercurrent extraction to obtain a ternary impurity-removing liquid; wherein the number of stages of the multi-stage countercurrent extraction is greater than or equal to 5, and an extractant and a diluent are added during the multi-stage countercurrent extraction process, and the volume ratio of the extractant to the diluent is (5-8):(3-4); in the ternary impurity-removing liquid, the concentrations of calcium ions, magnesium ions, iron ions and aluminum ions are each independently less than 5 mg / L, and the concentration of fluoride ions is less than 200 mg / L.

[0065] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0066] Compared with the prior art, the present invention has the following beneficial effects:

[0067] The present invention first uses a calcium reagent to remove iron and aluminum, then adds fluoride to remove calcium and magnesium, and finally performs acidification and extraction to remove fluorine. This process not only avoids the introduction of sodium elements throughout the entire process, achieving the purpose of removing iron, aluminum, calcium, magnesium and fluorine in the ternary black powder leachate, but also converts the fluorine element into the form of hydrofluoric acid during the acidification process, so as to achieve efficient removal during the extraction and defluorination process, so that the fluorine concentration in the ternary impurity removal liquid is reduced to below 200 mg / L, showing an excellent defluorination effect. The process has the advantages of simple operation, simple equipment and low cost. In addition, this impurity removal method prevents the subsequent extraction stage from containing difficult-to-remove sodium impurities in the finished product after purification, and the extraction stage only needs to be purified by a semi-extraction process, which greatly reduces the alkali consumption of the extraction stage and has important application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 This is a process flow chart provided for Example 1 of the present invention. DETAILED DESCRIPTION

[0069] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0070] Example 1

[0071] This embodiment provides a method for removing impurities from a ternary black powder leachate, and the process flow chart thereof is as follows: Figure 1 As shown, the impurity removal method comprises the following steps:

[0072] (1) crushing, disassembling and screening the waste ternary batteries to obtain ternary black powder;

[0073] Concentrated sulfuric acid with a mass fraction of 85% is added to the ternary black powder to adjust the pH to 1-2, and then hydrogen peroxide is added and mixed, and reduction leaching is performed at 70° C. for 4 hours to obtain a ternary black powder leachate; wherein the concentration of calcium ions in the ternary black powder leachate is 168.7 mg / L, the concentration of magnesium ions is 53.1 mg / L, the concentration of iron ions is 6.43 g / L, the concentration of aluminum ions is 5.84 g / L, and the concentration of fluoride ions is 7.83 g / L.

[0074] (2) 10 L of the ternary black powder leachate was taken into a glass reactor, the temperature was raised to 70 ° C, and a calcium hydroxide slurry with a concentration of 20 wt% was slowly added to adjust the pH of the ternary black powder leachate to 4.5. The first-level impurity removal was carried out under stirring for 2 hours and then filtered to obtain an iron and aluminum-removing leachate.

[0075] (3) adding manganese fluoride to the iron-aluminum-removed leachate, performing secondary impurity removal at 25° C. under stirring for 3 h, filtering after the secondary impurity removal to obtain a calcium-magnesium-removed leachate; wherein the amount of manganese fluoride added is 4 times the theoretical amount, that is, the molar ratio (Ca+Mg):F=1:8.

[0076] (4) Under stirring conditions, adding concentrated sulfuric acid to the decalcified magnesium leachate for acidification to obtain an acidified liquid; wherein the mass volume ratio of concentrated sulfuric acid to the decalcified magnesium leachate is 30 g / L, the acidification temperature is 20° C., and the acidification time is 0.5 h.

[0077] (5) At 25° C., the acidified liquid was subjected to five-stage countercurrent extraction by adding TBP and kerosene in a volume ratio of 6:4 according to the volume ratio of the organic phase to the aqueous phase of 1:1 to obtain a ternary impurity-removing liquid. In the ternary impurity-removing liquid, the concentration of calcium ions was 3.7 mg / L, the concentration of magnesium ions was 1.8 mg / L, the concentration of iron ions was 1.3 mg / L, the concentration of aluminum ions was 0.1 mg / L, and the concentration of fluoride ions was 162 mg / L.

[0078] Example 2

[0079] This embodiment provides a method for removing impurities from a ternary black powder leachate, the method comprising the following steps:

[0080] (1) crushing, disassembling and screening the waste ternary batteries to obtain ternary black powder;

[0081] Concentrated sulfuric acid with a mass fraction of 85% is added to the ternary black powder to adjust the pH to 1-2, and then hydrogen peroxide is added and mixed, and reduction leaching is performed at 70° C. for 4 hours to obtain a ternary black powder leachate; wherein the concentration of calcium ions in the ternary black powder leachate is 168.7 mg / L, the concentration of magnesium ions is 53.1 mg / L, the concentration of iron ions is 6.43 g / L, the concentration of aluminum ions is 5.84 g / L, and the concentration of fluoride ions is 7.83 g / L.

[0082] (2) 10 L of the ternary black powder leachate was taken into a glass reactor, the temperature was raised to 70 ° C, and a calcium hydroxide slurry with a concentration of 20 wt% was slowly added to adjust the pH of the ternary black powder leachate to 4.5. The first-level impurity removal was carried out under stirring for 2 hours and then filtered to obtain an iron and aluminum-removing leachate.

[0083] (3) adding manganese fluoride to the iron-aluminum-removed leachate, performing secondary impurity removal at 25° C. under stirring for 3 h, filtering after the secondary impurity removal to obtain a calcium-magnesium-removed leachate; wherein the amount of manganese fluoride added is 3.5 times the theoretical amount, that is, the molar ratio (Ca+Mg):F=1:7.

[0084] (4) Under stirring conditions, adding concentrated sulfuric acid to the decalcified magnesium leachate for acidification to obtain an acidified liquid; wherein the mass volume ratio of concentrated sulfuric acid to the decalcified magnesium leachate is 30 g / L, the acidification temperature is 20° C., and the acidification time is 0.5 h.

[0085] (5) At 25° C., the acidified liquid was subjected to five-stage countercurrent extraction by adding TBP and kerosene in a volume ratio of 6:4 according to the volume ratio of the organic phase to the aqueous phase of 1:1 to obtain a ternary impurity-removing liquid. In the ternary impurity-removing liquid, the concentration of calcium ions was 4.1 mg / L, the concentration of magnesium ions was 4.7 mg / L, the concentration of iron ions was 1.8 mg / L, the concentration of aluminum ions was 0.1 mg / L, and the concentration of fluoride ions was 170 mg / L.

[0086] Example 3

[0087] This embodiment provides a method for removing impurities from a ternary black powder leachate, the method comprising the following steps:

[0088] (1) crushing, disassembling and screening the waste ternary lithium batteries to obtain ternary black powder;

[0089] Concentrated sulfuric acid with a mass fraction of 85% is added to the ternary black powder to adjust the pH to 1-2, and then hydrogen peroxide is added and mixed, and reduction leaching is performed at 70° C. for 4 hours to obtain a ternary black powder leachate; wherein the concentration of calcium ions in the ternary black powder leachate is 168.7 mg / L, the concentration of magnesium ions is 53.1 mg / L, the concentration of iron ions is 6.43 g / L, the concentration of aluminum ions is 5.84 g / L, and the concentration of fluoride ions is 7.83 g / L.

[0090] (2) 10 L of the ternary black powder leachate was taken into a glass reactor, the temperature was raised to 70 ° C, and a calcium hydroxide slurry with a concentration of 20 wt% was slowly added to adjust the pH of the ternary black powder leachate to 4.5. The first-level impurity removal was carried out under stirring for 2 hours and then filtered to obtain an iron and aluminum-removing leachate.

[0091] (3) adding manganese fluoride to the iron-aluminum-removed leachate, performing secondary impurity removal at 25° C. under stirring for 3 h, filtering after the secondary impurity removal to obtain a calcium-magnesium-removed leachate; wherein the amount of manganese fluoride added is 3.5 times the theoretical amount, that is, the molar ratio (Ca+Mg):F=1:7.

[0092] (4) Under stirring conditions, adding concentrated sulfuric acid to the decalcified magnesium leachate for acidification to obtain an acidified liquid; wherein the mass volume ratio of concentrated sulfuric acid to the decalcified magnesium leachate is 30 g / L, the acidification temperature is 25° C., and the acidification time is 0.5 h.

[0093] (5) At 25° C., the acidified liquid was subjected to five-stage countercurrent extraction by adding TBP, kerosene, and TOA in a volume ratio of 4:2:4 according to the volume ratio of the organic phase to the aqueous phase of 1:1 to obtain a ternary impurity-removing liquid. In the ternary impurity-removing liquid, the concentration of calcium ions was 4.8 mg / L, the concentration of magnesium ions was 4.2 mg / L, the concentration of iron ions was 0.1 mg / L, the concentration of aluminum ions was 0.1 mg / L, and the concentration of fluoride ions was 163 mg / L.

[0094] Example 4

[0095] The difference between this embodiment and embodiment 1 is that the amount of fluoride added is 5 times the theoretical amount, that is, the molar ratio (Ca+Mg):F=1:10.

[0096] The remaining impurity removal methods and parameters remained consistent with those in Example 1.

[0097] In the above-mentioned ternary impurity removal liquid, the concentration of calcium ions is 2.2 mg / L, the concentration of magnesium ions is 1.5 mg / L, the concentration of iron ions is 0.01 mg / L, the concentration of aluminum ions is 0.1 mg / L, and the concentration of fluoride ions is 167 mg / L.

[0098] Example 5

[0099] The difference between this embodiment and embodiment 1 is that the mass volume ratio of the concentrated sulfuric acid to the calcium and magnesium removal leachate in step (4) is 20 g / L.

[0100] The remaining impurity removal methods and parameters remained consistent with those in Example 1.

[0101] In the above-mentioned ternary impurity removal liquid, the concentration of calcium ions is 2.0 mg / L, the concentration of magnesium ions is 1.4 mg / L, the concentration of iron ions is 0.7 mg / L, the concentration of aluminum ions is 0.1 mg / L, and the concentration of fluoride ions is 192 mg / L.

[0102] Example 6

[0103] The difference between this embodiment and embodiment 1 is that the mass volume ratio of the concentrated sulfuric acid to the calcium and magnesium removal leachate in step (4) is 80 g / L.

[0104] The remaining impurity removal methods and parameters remained consistent with those in Example 1.

[0105] In the above-mentioned ternary impurity removal liquid, the concentration of calcium ions is 3.2 mg / L, the concentration of magnesium ions is 1.1 mg / L, the concentration of iron ions is 0.5 mg / L, the concentration of aluminum ions is 0.1 mg / L, and the concentration of fluoride ions is 141 mg / L.

[0106] Example 7

[0107] The difference between this embodiment and embodiment 1 is that the 5-stage countercurrent extraction is adjusted to 6-stage countercurrent extraction.

[0108] The remaining impurity removal methods and parameters remained consistent with those in Example 1.

[0109] In the above-mentioned ternary impurity removal liquid, the concentration of calcium ions is 2.8 mg / L, the concentration of magnesium ions is 2.1 mg / L, the concentration of iron ions is 0.8 mg / L, the concentration of aluminum ions is 0.1 mg / L, and the concentration of fluoride ions is 154 mg / L.

[0110] Example 8

[0111] The difference between this embodiment and embodiment 1 is that the volume ratio of TBP to kerosene is 4:6.

[0112] The remaining impurity removal methods and parameters remained consistent with those in Example 1.

[0113] In the above-mentioned ternary impurity removal liquid, the concentration of calcium ions is 4.1 mg / L, the concentration of magnesium ions is 2.0 mg / L, the concentration of iron ions is 1.1 mg / L, the concentration of aluminum ions is 0.3 mg / L, and the concentration of fluoride ions is 198 mg / L.

[0114] Example 9

[0115] The difference between this embodiment and embodiment 1 is that the volume ratio of TBP to kerosene is 8:2.

[0116] The remaining impurity removal methods and parameters remained consistent with those in Example 1.

[0117] In the above-mentioned ternary impurity removal liquid, the concentration of calcium ions is 3.8 mg / L, the concentration of magnesium ions is 1.1 mg / L, the concentration of iron ions is 1 mg / L, the concentration of aluminum ions is 0.1 mg / L, and the concentration of fluoride ions is 161 mg / L.

[0118] Example 10

[0119] The difference between this embodiment and embodiment 1 is that the amount of fluoride added is 1 times the theoretical amount, that is, the molar ratio (Ca+Mg):F=1:2.

[0120] The remaining impurity removal methods and parameters remained consistent with those in Example 1.

[0121] In the above-mentioned ternary impurity removal liquid, the concentration of calcium ions is 342 mg / L, the concentration of magnesium ions is 97 mg / L, the concentration of iron ions is 4.7 mg / L, the concentration of aluminum ions is 2.1 mg / L, and the concentration of fluoride ions is 178 mg / L.

[0122] Example 11

[0123] The difference between this embodiment and embodiment 1 is that the amount of fluoride added is 5.5 times the theoretical amount, that is, the molar ratio (Ca+Mg):F=1:11.

[0124] The remaining impurity removal methods and parameters remained consistent with those in Example 1.

[0125] In the above-mentioned ternary impurity removal liquid, the concentration of calcium ions is 1.2 mg / L, the concentration of magnesium ions is 0.7 mg / L, the concentration of iron ions is 1.5 mg / L, the concentration of aluminum ions is 0.1 mg / L, and the concentration of fluoride ions is 176 mg / L.

[0126] Example 12

[0127] The difference between this embodiment and embodiment 1 is that the concentrated sulfuric acid in step (4) is replaced by hydrochloric acid.

[0128] The remaining impurity removal methods and parameters remained consistent with those in Example 1.

[0129] In the above-mentioned ternary impurity removal liquid, the concentration of calcium ions is 4.5 mg / L, the concentration of magnesium ions is 2.1 mg / L, the concentration of iron ions is 0.8 mg / L, the concentration of aluminum ions is 0.2 mg / L, and the concentration of fluoride ions is 3.5 g / L.

[0130] Example 13

[0131] The difference between this embodiment and embodiment 1 is that the mass volume ratio of the concentrated sulfuric acid to the calcium and magnesium removal leachate in step (4) is 10 g / L.

[0132] The remaining impurity removal methods and parameters remained consistent with those in Example 1.

[0133] In the above-mentioned ternary impurity removal liquid, the concentration of calcium ions is 3.9 mg / L, the concentration of magnesium ions is 2.0 mg / L, the concentration of iron ions is 0.8 mg / L, the concentration of aluminum ions is 0.1 mg / L, and the concentration of fluoride ions is 371 mg / L.

[0134] Example 14

[0135] The difference between this embodiment and embodiment 1 is that the mass volume ratio of the concentrated sulfuric acid to the calcium and magnesium removal leachate in step (4) is 90 g / L.

[0136] The remaining impurity removal methods and parameters remained consistent with those in Example 1.

[0137] In the above-mentioned ternary impurity removal liquid, the concentration of calcium ions is 2.2 mg / L, the concentration of magnesium ions is 3.1 mg / L, the concentration of iron ions is 1.1 mg / L, the concentration of aluminum ions is 0.1 mg / L, and the concentration of fluoride ions is 145 mg / L.

[0138] Example 15

[0139] The difference between this embodiment and embodiment 1 is that the 5-stage countercurrent extraction is adjusted to a 4-stage countercurrent extraction.

[0140] The remaining impurity removal methods and parameters remained consistent with those in Example 1.

[0141] In the above-mentioned ternary impurity removal liquid, the concentration of calcium ions is 3.5 mg / L, the concentration of magnesium ions is 1.7 mg / L, the concentration of iron ions is 1.7 mg / L, the concentration of aluminum ions is 0.2 mg / L, and the concentration of fluoride ions is 340 mg / L.

[0142] Example 16

[0143] The difference between this embodiment and embodiment 1 is that the kerosene is replaced by an equal volume of TBP.

[0144] The remaining impurity removal methods and parameters remained consistent with those in Example 1.

[0145] In the above-mentioned ternary impurity removal liquid, the concentration of calcium ions is 3.9 mg / L, the concentration of magnesium ions is 2.2 mg / L, the concentration of iron ions is 1.3 mg / L, the concentration of aluminum ions is 0.1 mg / L, and the concentration of fluoride ions is 152 mg / L.

[0146] Example 17

[0147] The difference between this embodiment and embodiment 1 is that the TBP and kerosene are replaced by an equal total volume of N235 extractant;

[0148] The remaining impurity removal methods and parameters remained consistent with those in Example 1.

[0149] In the above-mentioned ternary impurity removal liquid, the concentration of calcium ions is 3.2 mg / L, the concentration of magnesium ions is 2.0 mg / L, the concentration of iron ions is 1.5 mg / L, the concentration of aluminum ions is 0.1 mg / L, and the concentration of fluoride ions is 211 mg / L.

[0150] Comparative Example 1

[0151] The difference between this comparative example and Example 1 is that the calcium hydroxide slurry with a concentration of 20wt% in step (2) is replaced by liquid caustic soda.

[0152] The remaining impurity removal methods and parameters remained consistent with those in Example 1.

[0153] In the above-mentioned ternary impurity removal liquid, the concentration of calcium ions is 2.1 mg / L, the concentration of magnesium ions is 0.7 mg / L, the concentration of iron ions is 0.01 mg / L, the concentration of aluminum ions is 0.01 mg / L, and the concentration of fluoride ions is 179 mg / L.

[0154] Comparative Example 2

[0155] The difference between this comparative example and Example 1 is that step (4) is not performed.

[0156] The remaining impurity removal methods and parameters remained consistent with those in Example 1.

[0157] In the above-mentioned ternary impurity removal liquid, the concentration of calcium ions is 4.4 mg / L, the concentration of magnesium ions is 2.8 mg / L, the concentration of iron ions is 0.7 mg / L, the concentration of aluminum ions is 0.1 mg / L, and the concentration of fluoride ions is 3.77 g / L.

[0158] Comparative Example 3

[0159] The difference between this comparative example and Example 1 is that step (5) is not performed.

[0160] The remaining impurity removal methods and parameters remained consistent with those in Example 1.

[0161] In the above-mentioned ternary impurity removal liquid, the concentration of calcium ions is 2.8 mg / L, the concentration of magnesium ions is 2.4 mg / L, the concentration of iron ions is 0.8 mg / L, the concentration of aluminum ions is 0.3 mg / L, and the concentration of fluoride ions is 3.48 g / L.

[0162] analyze

[0163] It can be seen from Examples 1 and 10-11 that if the amount of fluoride added is too little, the calcium and magnesium contents in the filtrate will be too high; if the amount of fluoride added is too much, the fluoride ion concentration in the solution will be high, which will increase the cost of the process, and the fluoride ion concentration in the impurity removal liquid will be high, resulting in poor defluorination effect.

[0164] It can be seen from Examples 1 and 12 that if hydrochloric acid is used for acidification, compared with concentrated sulfuric acid, the acidified H content will be lower, less HF will be formed, the fluorine extraction effect in the extraction stage will be poor, and the fluorine content in the filtrate will be higher.

[0165] It can be seen from Example 1 and Examples 13-14 that if the amount of concentrated sulfuric acid added during the acidification process is too small, less HF is formed, the fluorine extraction effect in the extraction section is poor, and the fluorine content in the filtrate is high; if the amount of concentrated sulfuric acid added during the acidification process is too large, the process cost is increased, but the fluorine removal effect is not significantly improved, and the cost-effectiveness is low.

[0166] It can be seen from Example 1 and Example 15 that if the 5-stage countercurrent extraction is adjusted to a 4-stage countercurrent extraction, the fluorine extraction rate in the extraction stage is low and the fluorine content in the filtrate is high.

[0167] It can be seen from Examples 1 and 16 that if only TBP is used for five-stage countercurrent extraction, the process cost is high and the organic phase is viscous.

[0168] It can be seen from Examples 1 and 17 that if N235 extractant is used for five-stage countercurrent extraction, the extraction rate of hydrofluoric acid is relatively low.

[0169] It can be seen from Example 1 and Comparative Example 1 that if liquid alkali is used to adjust the pH of the leachate to remove iron and aluminum, the filter residue is difficult to filter and Na ions are introduced, which are difficult to remove subsequently.

[0170] It can be seen from Example 1 and Comparative Example 2 that if the acidification step is not performed, no hydrofluoric acid molecules will be formed and the extractant will not be able to extract F ions.

[0171] It can be seen from Example 1 and Comparative Example 3 that if the extraction and defluorination process is not performed, the fluorine content in the filtrate will be high.

[0172] It should be noted that while the present invention illustrates the process method through the above-described embodiments, the present invention is not limited to the above-described process steps, and does not necessarily rely on the above-described process steps for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent replacements for the raw materials used, additions of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for removing impurities from a ternary black powder leachate, characterized in that: The impurity removal method comprises the following steps: Calcium reagents are used to adjust the pH of the ternary black powder leachate to the target value, and primary impurity removal is performed to obtain an iron and aluminum-removed leachate; The iron and aluminum removal leachate is mixed with fluoride and subjected to secondary impurity removal to obtain a calcium and magnesium removal leachate; The calcium and magnesium removal leachate is acidified and extracted to remove fluorine to obtain a ternary impurity removal liquid.

2. The impurity removal method according to claim 1, wherein The preparation steps of the ternary black powder leachate include: Mixing ternary black powder, acid solution and reducing agent, and performing reduction leaching to obtain ternary black powder leachate; Preferably, the acid solution comprises sulfuric acid; Preferably, the reducing agent comprises hydrogen peroxide; Preferably, the reduction leaching temperature is 60-90°C; Preferably, the reduction leaching time is 2-6 hours.

3. The impurity removal method according to claim 1 or 2, characterized in that: The impurity ions in the ternary black powder leachate include calcium ions, magnesium ions, iron ions, aluminum ions and fluoride ions; Preferably, the concentration of fluoride ions in the ternary black powder leachate is greater than 4 g / L; Preferably, the calcium reagent includes any one of calcium hydroxide slurry, calcium oxide or calcium carbonate, or a combination of at least two of them.

4. The impurity removal method according to any one of claims 1 to 3, characterized in that: The temperature of the first-level impurity removal is 60-90°C; Preferably, the time for the primary impurity removal is 1.5-3 hours; Preferably, the primary impurity removal process is accompanied by stirring.

5. The impurity removal method according to any one of claims 1 to 4, characterized in that: The fluoride is manganese fluoride; Preferably, the amount of fluoride added is 3.5-5 times the theoretical amount.

6. The impurity removal method according to any one of claims 1 to 5, characterized in that: The temperature of the secondary impurity removal is 20-60°C; Preferably, the secondary impurity removal time is 2-4 hours; Preferably, the secondary impurity removal process is accompanied by stirring.

7. The impurity removal method according to any one of claims 1 to 6, characterized in that: During the acidification process, the acidifying agent used includes concentrated sulfuric acid; Preferably, the mass volume ratio of the concentrated sulfuric acid to the calcium and magnesium removal leachate is 20-80 g / L; Preferably, the acidification time is 0.5-1h; Preferably, the acidification process is accompanied by stirring.

8. The impurity removal method according to any one of claims 1 to 7, characterized in that: The extraction and defluorination method includes multi-stage countercurrent extraction; Preferably, the number of stages of the multi-stage countercurrent extraction is greater than or equal to 5.

9. The impurity removal method according to any one of claims 1 to 8, characterized in that: In the process of extractive defluorination, the extractant used includes TBP; Preferably, during the extraction and defluorination process, an auxiliary extractant is also added, and the auxiliary extractant includes TOA; Preferably, a diluent is added during the extraction and defluorination process, and the diluent includes kerosene; Preferably, in the ternary impurity removal solution, the concentrations of calcium ions, magnesium ions, iron ions and aluminum ions are each independently less than 5 mg / L, and the concentration of fluoride ions is less than 200 mg / L.

10. The impurity removal method according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: (1) crushing and disassembling the waste batteries and screening them to obtain ternary black powder; The ternary black powder, acid solution and hydrogen peroxide are mixed and subjected to reduction leaching at 60-90° C. for 2-6 hours to obtain a ternary black powder leachate; wherein the impurity ions in the ternary black powder leachate include calcium ions, magnesium ions, iron ions, aluminum ions and fluoride ions, and the concentration of fluoride ions is greater than 4 g / L; (2) using a calcium reagent to adjust the pH of the ternary black powder leachate to 4.5-5, performing a primary impurity removal at 60-90° C. for 1.5-3 hours, stirring during the primary impurity removal process, and performing solid-liquid separation after the primary impurity removal to obtain an iron-aluminum-removed leachate; (3) mixing the iron and aluminum removal leachate with fluoride, and performing secondary impurity removal at 20-60° C. for 2-4 hours, stirring during the secondary impurity removal process, and performing solid-liquid separation after the secondary impurity removal to obtain a calcium and magnesium removal leachate; wherein the amount of fluoride added is 3.5-5 times the theoretical amount; (4) adding concentrated sulfuric acid to the decalcified magnesium leachate under stirring to acidify the solution to obtain an acidified solution; wherein the mass volume ratio of the concentrated sulfuric acid to the decalcified magnesium leachate is 20-80 g / L, the acidification temperature is room temperature, the acidification time is 0.5-1 h, and the acidified solution contains hydrofluoric acid; (5) Under the condition of 20-60° C., the acidified liquid is subjected to multi-stage countercurrent extraction to obtain a ternary impurity-removing liquid; wherein the number of stages of the multi-stage countercurrent extraction is greater than or equal to 5, and an extractant and a diluent are added during the multi-stage countercurrent extraction process, and the volume ratio of the extractant to the diluent is (4-8):(2-6); in the ternary impurity-removing liquid, the concentrations of calcium ions, magnesium ions, iron ions and aluminum ions are each independently less than 5 mg / L, and the concentration of fluoride ions is less than 200 mg / L.

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