An extractant, an extraction system and its application

Abstract

This invention relates to an extractant, an extraction system, and its application. The extractant is a dialkyl phosphate containing a benzene ring, and the benzene ring-containing dialkyl phosphate has the structure shown in Formula I. The extractant provided by this invention is a dialkyl phosphate compound containing a benzene ring. The extractant has a low pKa, high acidity, excellent extraction ability, and good separation effect. It can extract Ca at low pH and efficiently separate it from a large number of coexisting metal elements such as Mn, Ni, and Co. This effectively eliminates the formation of calcium gypsum during metal element extraction and reduces the use of large amounts of hydrochloric acid in metal recovery back-extraction. Simultaneously, it enables the effective recovery of calcium products.

Description

Technical Field

[0001] This invention relates to the field of chemical separation technology, and in particular to an extractant, an extraction system, and its application. Background Technology

[0002] Calcium (Ca) is widely distributed in nature, often existing in the form of compounds. In hydrometallurgical extraction of target metal elements, calcium oxide (CaO) or calcium carbonate (CaCO3) is often used as a neutralizing agent to adjust the pH of the initial feed solution. During this process, calcium is introduced into the system. In sulfuric acid systems, the introduction of calcium compounds forms calcium sulfate (CaSO4). Due to the low water solubility of CaSO4, the saturated concentration remaining in the solution is generally 300-700 mg / L. During metal extraction, especially when using acidic phosphorus extractants, a certain amount of Ca is extracted into the organic phase. After extraction, the acidity is often increased for washing, which results in Ca being extracted in the extraction section and then back-extracted in the washing section, leading to Ca accumulation in the extraction equipment. When Ca... 2+ With SO4 2- When the concentration product exceeds the saturation dissociation of CaSO4, CaSO4 precipitate forms in the system, which is the calcium gypsum problem commonly encountered in hydrometallurgy. The formation of calcium gypsum will cause scaling in the extraction equipment and will also cause emulsification of the extractable phase, thus seriously affecting the implementation of extraction.

[0003] However, when Ca is extracted simultaneously with other ions, HCl must be used for back-extraction to avoid CaSO4 precipitation. In metallurgical processes using H2SO4, a large amount of HCl is also required for back-extraction to prevent CaSO4 precipitation, which has a significant negative impact on the metallurgical process, increases metallurgical costs, and the process cannot effectively recover calcium-containing compounds, resulting in a waste of resources.

[0004] Existing technology CN106906361A discloses an extraction method to remove calcium and magnesium as an alternative to chemical methods. This method uses a P204 organic phase with sodium hydroxide saponification. Based on the relationship between the extraction rate of various metals by P204 and the equilibrium pH, the pH value is adjusted, and the number of extraction stages is controlled. Impurities such as iron, zinc, calcium, and manganese are extracted from a cobalt-tin solution. Calcium, copper, manganese, and zinc are loaded into the organic phase, and then back-extracted with hydrochloric acid to form a solution of calcium chloride, copper, manganese, and zinc. Cobalt, nickel, and magnesium enter the raffinate and proceed to the next process. The cobalt-nickel separation line is relatively far apart; cobalt enters the P507 loaded organic phase, while nickel and magnesium enter the raffinate. The loaded organic phase is then back-extracted to form a cobalt chloride solution. This method has advantages such as less clogging of the extraction tank in the extraction section; reduced impurities; stable product quality; and high product yield and quality, making it suitable for applications in the chemical calcium and magnesium removal process in the cobalt industry. However, this existing technology still uses a large amount of hydrochloric acid back-extraction, resulting in high costs and resource waste.

[0005] Prior art CN112760482A discloses a method for reducing calcium sulfate deposition during P204 extraction and impurity removal. The method involves washing the extracted P204-loaded organic phase, including a primary wash and a secondary wash. Water and hydrochloric acid are added to the P204-loaded organic phase during both the primary and secondary washes. This method reduces the amount of sulfate ions entrained in the organic phase, thereby preventing the reaction of sulfate ions with calcium sulfate during the washing stage. 2+ The problem lies in preventing calcium sulfate from reaching saturation during the washing process, thereby reducing calcium sulfate precipitation. However, the existing method still consumes a large amount of acid to reduce calcium sulfate precipitation and cannot effectively recover calcium products.

[0006] The shortcomings of existing technologies mean that providing an extraction system capable of directly extracting and recovering calcium from feed solutions has become an urgent problem to be solved. Summary of the Invention

[0007] To address the aforementioned technical problems, the present invention aims to provide an extractant, an extraction system, and an application. The extractant provided by the present invention is a dialkyl phosphate containing a benzene ring. This extractant is highly acidic and exhibits excellent extraction capabilities, enabling the separate extraction of calcium at low pH levels. Furthermore, it can efficiently separate calcium from a large number of coexisting metal elements such as Mn, Ni, and Co, thereby eliminating the formation of calcium gypsum during metal element extraction, reducing the amount of acid used in metal recovery and back-extraction, and simultaneously achieving effective recovery of calcium products.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides an extractant, wherein the extractant is a benzene-ring-containing dialkyl phosphate ester having a structure as shown in Formula I:

[0010]

[0011] R1 and R2 are independently selected from any one of straight-chain or branched alkyl groups of C1-C12 (e.g., C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11 or C12).

[0012] The extractant provided by the present invention is a dialkyl phosphate ester containing benzene rings with the structure shown in Formula I. The extractant is a dialkyl phosphate ester structure formed by two alkylbenzene rings and phosphate ester functional groups. The electron-withdrawing effect of the two benzene rings in the extractant makes the extractant highly acidic and has excellent extraction ability. The extractant provided by this invention is a dialkyl phosphate compound containing a benzene ring. It has high acidity, excellent extraction ability, and good separation effect. It can extract calcium at low pH and can efficiently separate it from a large number of coexisting elements such as Mn, Ni, and Co. On the one hand, after extracting calcium with a specific extractant, no washing measures are required during the extraction and separation process of other metal elements, and the problem of calcium gypsum generated during the extraction-washing process is avoided. On the other hand, when calcium is extracted and separated from other metal elements, calcium can be extracted and recovered from the feed solution. The calcium concentration in the raffinate is extremely low during the recovery of other metal elements. The amount of acid used, especially hydrochloric acid, can be greatly reduced during the back-extraction process of recovering other metals. At the same time, the dialkyl phosphate extractant containing a benzene ring provided by this invention can also simplify the separation process of calcium from other metal elements, thereby effectively reducing the operating cost of metal element separation and enabling the effective recovery of large amounts of calcium products, reducing resource waste.

[0013] Preferably, R1 and R2 are the same or different, but preferably the same.

[0014] Preferably, the benzene ring-containing dialkyl phosphate includes any one or a combination of at least two of the following: di(4-methyl)phenyl phosphate, di(4-ethyl)phenyl phosphate, di(4-propyl)phenyl phosphate, di(4-butyl)phenyl phosphate, di(4-pentyl)phenyl phosphate, di(4-hexyl)phenyl phosphate, di(4-heptyl)phenyl phosphate, di(4-octyl)phenyl phosphate, di(4-nonyl)phenyl phosphate, di(4-decyl)phenyl phosphate, di(4-undecyl)phenyl phosphate, or di(4-dodecyl)phenyl phosphate.

[0015] As a preferred embodiment of the present invention, the benzene-containing dialkyl phosphate ester having the structure shown in Formula I can be purchased commercially or prepared using p-alkylphenol and phosphorus trichloride as raw materials. Exemplarily, the preparation route of the benzene-containing dialkyl phosphate ester is as follows:

[0016]

[0017] Secondly, the present invention provides an extraction system comprising the extractant described in the first aspect.

[0018] The extraction system provided by this invention contains a benzene ring-containing dialkyl phosphate with a specific chemical formula according to the first aspect. It has excellent extraction and separation capabilities, can extract Ca at low pH, and can efficiently separate from a large number of coexisting metal elements such as Mn, Ni, and Co. This effectively eliminates the formation of calcium gypsum during the metal element extraction process, reduces the use of large amounts of hydrochloric acid during metal recovery and back-extraction, and also enables the effective recovery of calcium products.

[0019] Preferably, the extraction system further includes a diluent.

[0020] Preferably, the diluent comprises any one or a combination of at least two of kerosene, aromatic hydrocarbons, or aliphatic hydrocarbons.

[0021] Preferably, the aromatic hydrocarbon includes any one or a combination of at least two of benzene, toluene, or xylene.

[0022] Preferably, the aliphatic hydrocarbon includes any one or a combination of at least two of n-hexane, cyclohexane, n-heptane, or petroleum ether.

[0023] Preferably, the volume percentage of the extractant in the extraction system is 5-50 vol%, such as 5 vol%, 10 vol%, 15 vol%, 20 vol%, 25 vol%, 30 vol%, 35 vol%, 40 vol%, 45 vol%, or 50 vol%.

[0024] Preferably, the extraction system further includes a phase modifier.

[0025] Preferably, in the extraction system, the phase modifier includes a non-water-soluble alcohol or a trialkyl phosphate ester.

[0026] Preferably, the volume percentage of the phase modifier in the extraction system is 1-10 vol%, for example, 1 vol%, 2 vol%, 3 vol%, 4 vol%, 5 vol%, 6 vol%, 7 vol%, 8 vol%, 9 vol%, or 10 vol%.

[0027] Preferably, the extraction system comprises, by volume percentage: 5-50 vol% extractant, 1-10 vol% phase modifier, and the remainder being diluent.

[0028] Thirdly, the present invention provides the application of the extractant according to the first aspect in the separation, extraction or purification of metals.

[0029] The extractant provided by this invention can be used in the separation, extraction, and purification of metals. It preferentially extracts calcium under lower pH conditions, achieving separate extraction of calcium, and can separate it from coexisting metal elements such as Mn, Ni, and Co. The specific extractant provided by this invention is significant in the calcium extraction and separation process, eliminating the formation of calcium gypsum during metal element extraction. Simultaneously, it reduces the amount of hydrochloric acid used during back-extraction in metal element separation. This extractant is applicable to various fields; for example, it can be used for the recovery of metal elements from spent ternary lithium batteries.

[0030] Preferably, the metal comprises any one or a combination of at least two of calcium, manganese, nickel, cobalt, magnesium, zinc, or copper.

[0031] Fourthly, the present invention provides an extraction method for extracting calcium, the extraction method comprising the following steps:

[0032] (1) The calcium-containing liquid is extracted using the extraction system described in the second aspect. After separation, a calcium-loaded organic phase and raffinate are obtained.

[0033] (2) The calcium-loaded organic phase is back-extracted to obtain a calcium-enriched back-extracting solution.

[0034] The calcium extraction method provided by this invention employs a specific extraction system to extract and separate calcium-containing feed solutions. The benzene-ring-containing dialkyl phosphate extractant in the specific extraction system can achieve the separate extraction of calcium from the feed solution at low pH, thereby separating calcium from other coexisting metal elements. Combined with the back-extraction process of the calcium-loaded organic phase obtained after extraction, a calcium-enriched back-extraction solution can be recovered. Furthermore, due to the excellent extraction capability of the extractant, the calcium content in the raffinate after extraction is low, thereby eliminating the generation of calcium gypsum in the raffinate during subsequent separation and recovery processes and reducing the acid consumption during back-extraction in the metal element separation and recovery process. At the same time, the use of the specific extraction system can also shorten the process of separating calcium from other metals, thereby effectively reducing the operating costs in the metal extraction, separation, and recovery process.

[0035] Preferably, the calcium ion concentration in the calcium-containing liquid in step (1) is 0.0001-1 g / L, such as 0.0001 g / L, 0.0005 g / L, 0.001 g / L, 0.005 g / L, 0.01 g / L, 0.05 g / L, 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 mol / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, or 1 g / L.

[0036] Preferably, the pH of the calcium-containing solution in step (1) is 1-5, such as 1, 2, 3, 4 or 5, preferably 1-3.

[0037] Preferably, the volume ratio of the extraction system in step (1) to the calcium-containing liquid is (1-500):100, such as 1:100, 10:100, 20:100, 50:100, 100:100, 150:100, 200:100, 250:100, 300:100, 350:100, 400:100, 450:100 or 500:100, etc.

[0038] Preferably, the extraction in step (1) is a multi-stage countercurrent extraction.

[0039] Preferably, the number of stages in the multi-stage countercurrent extraction is 2-5 stages, such as 2 stages, 3 stages, 4 stages, or 5 stages.

[0040] Preferably, the back-extraction reagent used in step (2) includes an HCl (hydrochloric acid) solution with a concentration of 4-6 mol / L, such as 4 mol / L, 4.5 mol / L, 5 mol / L, 5.5 mol / L, or 6 mol / L.

[0041] Preferably, the volume ratio of the back-extraction reagent to the calcium-loaded organic phase is 1:(5-20), for example, 1:5, 1:6, 1:8, 1:10, 1:12, 1:14, 1:16, 1:18 or 1:20.

[0042] Preferably, the back-extraction in step (2) is a multi-stage countercurrent back-extraction.

[0043] Preferably, the multi-stage countercurrent back-extraction has 2-3 stages, such as 2 or 3 stages.

[0044] It should be noted that the calcium-containing liquid obtained by those skilled in the art within a reasonable scope is applicable to the calcium extraction method provided by the present invention. By way of example and not limitation, the calcium-containing liquid is derived from the leachate after acid leaching of waste ternary lithium batteries, the liquid obtained after calcium neutralization treatment of the leachate after acid leaching of waste ternary lithium batteries, etc.

[0045] For example, the calcium-containing solution is derived from the leachate after acid leaching of waste ternary lithium batteries, which has undergone calcium neutralization treatment. This solution is then used in the extraction and recovery of metal elements from waste ternary lithium batteries. The specific steps of the calcium extraction method include the following:

[0046] S1. The waste ternary battery material is leached with acid to obtain a leachate. The leachate contains metal elements including nickel, cobalt, manganese, copper, zinc, calcium, and magnesium. The leachate is then subjected to calcium neutralization treatment. The reagent for calcium neutralization treatment includes any one or a combination of at least two of calcium oxide, calcium hydroxide, or calcium carbonate to obtain the calcium-containing solution. The calcium ion concentration in the calcium-containing solution is 0.0001-1 g / L, and the pH of the calcium-containing solution is 1-5.

[0047] S2. The calcium-containing liquid is subjected to 2-5 stages of countercurrent extraction using the extraction system described in the second aspect, wherein the volume ratio of the extraction system to the calcium-containing liquid is (1-500):100, and the liquid is separated to obtain a calcium-loaded organic phase and a raffinate.

[0048] S3. The calcium-loaded organic phase is subjected to 2-3 stages of countercurrent back-extraction using HCl solution as the back-extraction reagent. The concentration of the HCl solution is 4-6 mol / L, and the volume ratio of the back-extraction reagent to the calcium-containing organic phase is 1:(5-20), to obtain a calcium-enriched back-extraction solution.

[0049] In the calcium extraction method provided by this invention, the raffinate obtained in step S2 can be extracted and recovered to obtain high-value metal elements using an existing extraction system.

[0050] Compared with the prior art, the present invention has at least the following beneficial effects:

[0051] The extractant provided by the present invention is a dialkyl phosphate ester containing benzene rings with the structure shown in Formula I. The extractant is a dialkyl phosphate ester structure formed by two alkylbenzene rings and phosphate ester functional groups. The electron-withdrawing effect of the two benzene rings in the extractant makes the extractant highly acidic and has excellent extraction ability. The extractant provided by this invention is a dialkyl phosphate compound containing a benzene ring. It has a low pKa, high acidity, excellent extraction ability, and good separation effect. It can extract calcium at low pH and can efficiently separate it from a large number of coexisting elements such as Mn, Ni, and Co. On the one hand, after extracting calcium with a specific extractant, no washing measures are required during the extraction and separation process of other metal elements, and the problem of calcium gypsum generated during the extraction-washing process is avoided. On the other hand, when calcium is extracted and separated from other metal elements, calcium can be extracted and recovered from the feed solution. The calcium concentration in the raffinate is extremely low during the recovery of other metal elements. The amount of acid used, especially hydrochloric acid, can be greatly reduced during the back-extraction process of recovering other metals. At the same time, the dialkyl phosphate extractant containing a benzene ring provided by this invention can also simplify the separation process of calcium from other metal elements, thereby effectively reducing the operating cost of metal element separation and enabling the effective recovery of large amounts of calcium products, reducing resource waste. Attached Figure Description

[0052] Figure 1 This is a graph showing the extraction rate of each metal element by the extraction system provided in Example 1 as a function of pH.

[0053] Figure 2 This is a graph showing the extraction rate of each metal element by the extraction system provided in Comparative Example 1 as a function of pH. Detailed Implementation

[0054] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0055] The materials used in the following specific embodiments of the present invention are obtained through the following means:

[0056] (1) Dialkyl phosphate containing benzene ring: can be purchased from the market or prepared using p-alkylphenol and phosphorus trichloride as raw materials.

[0057] Specifically, the di(4-octyl)phenyl phosphate is prepared from p-octylphenol and phosphorus trichloride via the following preparation route; the di(4-dodecyl)phenyl phosphate is prepared from p-dodecylphenol and phosphorus trichloride via the following preparation route; the di(4-propyl)phenyl phosphate is prepared from p-propylphenol and phosphorus trichloride via the following preparation route; the di(4-nonyl)phenyl phosphate is prepared from p-nonylphenol and phosphorus trichloride via the following preparation route; and the preparation route for dialkyl phosphates containing benzene rings is as follows:

[0058]

[0059] (2) Phase modifiers: Tributyl phosphate, isooctyl alcohol, sec-octanol and dodecyl alcohol were purchased from Beijing Chemical Plant.

[0060] (3) Diluents: Kerosene, n-hexane, petroleum ether, and n-heptane were purchased from Guangdong Maoming Petrochemical Company.

[0061] (4) The di(2-ethylhexyl) phosphate (P204) extractant was purchased from Shanghai Chemical Reagent Co., Ltd.

[0062] (5) Waste ternary battery materials: A lithium nickel cobalt manganese oxide (chemical formula LiNi) is used. 0.3 Co 0.3 Mn 0.3 A lithium-ion battery is constructed using O2 as the positive electrode, graphite as the negative electrode, and lithium hexafluorophosphate as the electrolyte. After charge-discharge cycles, the recycled ternary battery material is obtained by crushing, dismantling, flotation, and pyrolysis of the cycled battery.

[0063] Example 1

[0064] This embodiment provides an extraction system comprising, by volume percentage: 30 vol% extractant, 60 vol% diluent, and 10 vol% phase modifier. The extractant is di(4-octyl)phenyl phosphate, the diluent is kerosene, and the phase modifier is tributyl phosphate.

[0065] Example 2

[0066] This embodiment provides an extraction system comprising, by volume percentage: 5 vol% extractant, 90 vol% diluent, and 5 vol% phase modifier. The extractant is di(4-dodecyl)phenyl phosphate, the diluent is n-hexane, and the phase modifier is isooctyl alcohol.

[0067] Example 3

[0068] This embodiment provides an extraction system comprising, by volume percentage: 50 vol% extractant, 49 vol% diluent, and 1 vol% phase modifier. The extractant is di(4-propyl)phenyl phosphate, the diluent is petroleum ether, and the phase modifier is 2-octanol.

[0069] Example 4

[0070] This embodiment provides an extraction system comprising, by volume percentage: 5 vol% extractant, 85 vol% diluent, and 10 vol% phase modifier. The extractant is di(4-nonyl)phenyl phosphate, the diluent is n-heptane, and the phase modifier is dodecyl alcohol.

[0071] Example 5

[0072] The only difference between this embodiment and Embodiment 1 is that the phase modifier is omitted in the extraction system provided in this embodiment; that is, the extractant is 40 vol% and the diluent is 60 vol% by volume percentage of the extraction system. All other contents are the same as in Embodiment 1.

[0073] Example 6

[0074] The only difference between this embodiment and Embodiment 1 is that, in this embodiment, the extraction system contains, by volume percentage, 2 vol% extractant, 88 vol% diluent, and 10 vol% phase modifier. All other contents are the same as in Embodiment 1.

[0075] Example 7

[0076] The only difference between this embodiment and Embodiment 1 is that, in this embodiment, the extraction system contains 55 vol% extractant, 35 vol% diluent, and 10 vol% phase modifier, based on the volume percentage of the extraction system. All other contents are the same as in Embodiment 1.

[0077] Comparative Example 1

[0078] The only difference between this comparative example and the previous example is that the extraction system provided in this comparative example uses di(4-octyl)phenyl phosphate as the extractant, instead of di(2-ethylhexyl) phosphate (P204). All other aspects are the same as in Example 1.

[0079] Application Example 1

[0080] This application example provides an extraction method for extracting calcium, the extraction method comprising the following steps:

[0081] S1. The waste ternary lithium battery material is leached with sulfuric acid at a concentration of 2 mol / L, and the mass ratio of waste ternary lithium battery material to sulfuric acid is 10:1 to obtain a leachate. The metal elements in the leachate include nickel, cobalt, manganese, copper, zinc, calcium and magnesium. The leachate is neutralized with calcium oxide to obtain a calcium-containing solution with a pH of 1. In the calcium-containing solution, the concentration of calcium ions is 0.6 g / L, the concentration of nickel ions is 38 g / L, the concentration of manganese ions is 21 g / L, the concentration of zinc ions is 0.01 g / L, the concentration of cobalt ions is 15 g / L, the concentration of copper ions is 2 g / L, and the concentration of magnesium ions is 0.05 g / L.

[0082] S2. The calcium-containing liquid obtained in step S1 was subjected to three-stage countercurrent extraction using the extraction system provided in Example 1. The volume ratio of the extraction system to the calcium-containing liquid was 1:4. After separation, a calcium-loaded organic phase and raffinate were obtained.

[0083] S3. A 4 mol / L HCl solution was used as the back-extraction reagent to perform a three-stage countercurrent back-extraction on the calcium-loaded organic phase obtained in step S2. The volume ratio of HCl solution to calcium-loaded organic phase was 1:10, resulting in an enriched calcium chloride solution.

[0084] Application Example 2

[0085] This application example provides an extraction method for extracting calcium, the extraction method comprising the following steps:

[0086] S1. The waste ternary lithium battery material is leached with sulfuric acid at a concentration of 2 mol / L, and the mass ratio of waste ternary lithium battery material to sulfuric acid is 10:1 to obtain a leachate. The metal elements in the leachate include nickel, cobalt, manganese, copper, zinc, calcium and magnesium. The leachate is neutralized with calcium oxide to obtain a calcium-containing solution with a pH of 1. In the calcium-containing solution, the concentration of calcium ions is 0.6 g / L, the concentration of nickel ions is 38 g / L, the concentration of manganese ions is 21 g / L, the concentration of zinc ions is 0.01 g / L, the concentration of cobalt ions is 15 g / L, the concentration of copper ions is 2 g / L, and the concentration of magnesium ions is 0.05 g / L.

[0087] S2. The calcium-containing liquid obtained in step S1 was subjected to four-stage countercurrent extraction using the extraction system provided in Example 2. The volume ratio of the extraction system to the calcium-containing liquid was 1:100. After separation, a calcium-loaded organic phase and raffinate were obtained.

[0088] S3. A 6 mol / L HCl solution was used as the back-extraction reagent to perform a two-stage countercurrent back-extraction on the calcium-loaded organic phase obtained in step S2. The volume ratio of HCl solution to calcium-loaded organic phase was 1:5, resulting in an enriched calcium chloride solution.

[0089] Application Example 3

[0090] This application example provides an extraction method for extracting calcium, the extraction method comprising the following steps:

[0091] S1. The waste ternary lithium battery material is leached with sulfuric acid at a concentration of 2 mol / L, and the mass ratio of waste ternary lithium battery material to sulfuric acid is 10:1 to obtain a leachate. The metal elements in the leachate include nickel, cobalt, manganese, copper, zinc, calcium and magnesium. The leachate is neutralized with calcium oxide to obtain a calcium-containing solution with a pH of 1. In the calcium-containing solution, the concentration of calcium ions is 0.6 g / L, the concentration of nickel ions is 38 g / L, the concentration of manganese ions is 21 g / L, the concentration of zinc ions is 0.01 g / L, the concentration of cobalt ions is 15 g / L, the concentration of copper ions is 2 g / L, and the concentration of magnesium ions is 0.05 g / L.

[0092] S2. The calcium-containing liquid obtained in step S1 was subjected to two-stage countercurrent extraction using the extraction system provided in Example 3. The volume ratio of the extraction system to the calcium-containing liquid was 1:2. After separation, a calcium-loaded organic phase and raffinate were obtained.

[0093] S3. A 5 mol / L HCl solution was used as the back-extraction reagent to perform a three-stage countercurrent back-extraction on the calcium-loaded organic phase obtained in step S2. The volume ratio of HCl solution to calcium-loaded organic phase was 1:20, resulting in an enriched calcium chloride solution.

[0094] Application Example 4

[0095] The extraction method for calcium provided in this application example is the same as that in application example 1, except that it uses the extraction system provided in example 4.

[0096] Application Example 5

[0097] The difference between this application example and Application Example 1 lies only in step S1 of the calcium extraction method provided in this application example: the waste ternary lithium battery material is leached with sulfuric acid at a concentration of 2 mol / L, with a mass ratio of waste ternary lithium battery material to sulfuric acid of 10:1, yielding a leachate. The leachate contains nickel, cobalt, manganese, copper, calcium, zinc, and magnesium. The leachate is then neutralized with calcium oxide to obtain a calcium-containing solution with a pH of 2. In this calcium-containing solution, the concentrations of calcium ions are 0.5 g / L, nickel ions 38 g / L, manganese ions 21 g / L, zinc ions 0.01 g / L, cobalt ions 15 g / L, copper ions 2 g / L, and magnesium ions 0.05 g / L. All other aspects are the same as in Application Example 1.

[0098] Application Example 6

[0099] The difference between this application example and Application Example 1 lies only in step S1 of the calcium extraction method provided in this application example: the waste ternary lithium battery material is leached with sulfuric acid at a concentration of 2 mol / L, with a mass ratio of waste ternary lithium battery material to sulfuric acid of 10:1, yielding a leachate. The leachate contains nickel, cobalt, manganese, copper, zinc, calcium, and magnesium. The leachate is then neutralized with calcium oxide to obtain a calcium-containing solution with a pH of 3. In this calcium-containing solution, the concentrations of calcium ions are 0.4 g / L, nickel ions 38 g / L, manganese ions 21 g / L, zinc ions 0.01 g / L, cobalt ions 15 g / L, copper ions 2 g / L, and magnesium ions 0.05 g / L. All other aspects are the same as in Application Example 1.

[0100] Application Example 7

[0101] The difference between this application example and Application Example 1 lies only in step S1 of the calcium extraction method provided in this application example: the waste ternary lithium battery material is leached with sulfuric acid at a concentration of 2 mol / L, with a mass ratio of waste ternary lithium battery material to sulfuric acid of 10:1, yielding a leachate. The leachate contains nickel, cobalt, manganese, copper, zinc, calcium, and magnesium. The leachate is then neutralized with calcium oxide to obtain a calcium-containing solution with a pH of 4. In this calcium-containing solution, the concentrations of calcium ions are 0.3 g / L, nickel ions 38 g / L, manganese ions 21 g / L, zinc ions 0.01 g / L, cobalt ions 15 g / L, copper ions 2 g / L, and magnesium ions 0.05 g / L. All other aspects are the same as in Application Example 1.

[0102] Application Example 8

[0103] The difference between this application example and Application Example 1 lies only in step S1 of the calcium extraction method provided in this application example: the waste ternary lithium battery material is leached with sulfuric acid at a concentration of 2 mol / L, with a mass ratio of waste ternary lithium battery material to sulfuric acid of 10:1, yielding a leachate. The leachate contains nickel, cobalt, manganese, copper, zinc, calcium, and magnesium. The leachate is then neutralized with calcium oxide to obtain a calcium-containing solution with a pH of 5. In this calcium-containing solution, the concentrations of calcium ions are 0.2 g / L, nickel ions 38 g / L, manganese ions 21 g / L, zinc ions 0.01 g / L, cobalt ions 15 g / L, copper ions 2 g / L, and magnesium ions 0.05 g / L. All other aspects are the same as in Application Example 1.

[0104] Application Example 9

[0105] The extraction method for calcium extraction provided in this application example is the same as that in application example 1, except that it uses the extraction system provided in example 5.

[0106] Application Example 10

[0107] The extraction method for calcium extraction provided in this application example is the same as that in application example 1, except that it uses the extraction system provided in example 6.

[0108] Application Example 11

[0109] The extraction method for calcium extraction provided in this application example is the same as that in application example 1, except that it uses the extraction system provided in example 7.

[0110] Comparative Application Example 1

[0111] The extraction method for calcium extraction provided in this comparative application example is the same as that in application example 1, except that it uses the extraction system provided in comparative example 1.

[0112] Comparative Application Example 2

[0113] The extraction method for calcium extraction provided in this comparative application example is the same as that in application example 5, except that it uses the extraction system provided in comparative example 1.

[0114] Comparative Application Example 3

[0115] The extraction method for calcium extraction provided in this comparative application example is the same as that in application example 6, except that it uses the extraction system provided in comparative example 1.

[0116] Comparative Application Example 4

[0117] The extraction method for calcium extraction provided in this comparative application example is the same as that in application example 7, except that it uses the extraction system provided in comparative example 1.

[0118] Comparative Application Example 5

[0119] The extraction method for calcium extraction provided in this comparative application example is the same as that in application example 8, except that it uses the extraction system provided in comparative example 1.

[0120] The metal ions in the enriched calcium chloride solution obtained from the extraction methods in the above application examples and comparative application examples were quantitatively analyzed using ICP-OES (inductively coupled plasma optical emission spectrometry). The metal ions in the raffinate obtained in step S2 were also quantitatively analyzed using ICP-OES, and the extraction rates of each metal ion were calculated. Specific test results are shown in Table 1.

[0121] Table 1

[0122]

[0123] The test results show that:

[0124] (1) As can be seen from Application Examples 1 to 8, the extractant provided by the present invention is a dialkyl phosphate containing a benzene ring. The extractant is highly acidic and has excellent extraction ability, realizing the separate extraction of calcium at low pH. Moreover, it can be efficiently separated from coexisting metal elements such as Mn, Ni, and Co, thereby eliminating the formation of calcium gypsum during the metal element extraction process, reducing the amount of acid used in the metal recovery back-extraction process, and also realizing the effective recovery of calcium products.

[0125] (2) By comparing Application Example 1 and Application Example 9, it can be seen that if the phase modifier is omitted in the extraction system of the present invention, the phase separation will be slow and the extraction effect will be affected.

[0126] (3) By comparing Application Example 1 and Application Examples 10-11, it can be seen that if the content of the extractant in the extraction system provided by the present invention is too low, the extraction rate of calcium will decrease and the extraction rate of other metal elements will increase, resulting in a poor calcium separation effect; if the content of the extractant is too high, the viscosity of the extraction system will be too high and the utilization rate of the organic phase will decrease, thereby affecting the extraction effect.

[0127] (4) By comparing Application Example 1 with Comparative Application Example 1, Application Example 5 with Comparative Application Example 2, Application Example 6 with Comparative Application Example 3, Application Example 7 with Comparative Application Example 4, and Application Example 8 with Comparative Application Example 5, it can be seen that compared with the separation effect of the extraction system composed of conventional P204 extractant on metal elements, the extraction system composed of benzene ring-containing dialkyl phosphate extractant provided by the present invention has a very strong extraction ability for calcium under specific pH conditions, and can achieve the separation of calcium element from other metal elements, and the separation effect is excellent.

[0128] Figure 1 and Figure 2 The extraction systems of Example 1 (using a benzene ring-containing dialkyl phosphate extractant) and Comparative Example 1 (using a conventional P204 extractant) are presented respectively, showing the pH variation curves of each metal element during metal extraction. Figure 1 and Figure 2 The comparison shows that the extraction system composed of dialkyl phosphate extractants containing benzene rings has a higher extraction effect on calcium. Under low pH conditions, it can effectively separate calcium from other metal elements. In contrast, the extraction system composed of conventional P204 extractant cannot effectively separate calcium from other metal elements under pH conditions of 1-5.

[0129] In summary, the extractant provided by the present invention is a dialkyl phosphate ester containing benzene rings with the structure shown in Formula I. The extractant is a dialkyl phosphate ester structure formed by two alkylbenzene rings and phosphate ester functional groups. The electron-withdrawing effect of the two benzene rings in the extractant makes the extractant highly acidic and has excellent extraction ability. The extractant provided by this invention is a dialkyl phosphate compound containing a benzene ring. It has a low pKa, high acidity, excellent extraction ability, and good separation effect. It can extract calcium at low pH and can efficiently separate it from a large number of coexisting elements such as Mn, Ni, and Co. On the one hand, after extracting calcium with a specific extractant, no washing measures are required during the extraction and separation process of other metal elements, and the problem of calcium gypsum generated during the extraction-washing process is avoided. On the other hand, when calcium is extracted and separated from other metal elements, calcium can be extracted and recovered from the feed solution. The calcium concentration in the raffinate is extremely low during the recovery of other metal elements. The amount of acid used, especially hydrochloric acid, can be greatly reduced during the back-extraction process of recovering other metals. At the same time, the dialkyl phosphate extractant containing a benzene ring provided by this invention can also simplify the separation process of calcium from other metal elements, thereby effectively reducing the operating cost of metal element separation and enabling the effective recovery of large amounts of calcium products, reducing resource waste.

[0130] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. An extractant, characterized in that, The extractant is a benzene-ring-containing dialkyl phosphate ester, which has the structure shown in Formula I: R1 and R2 are independently selected from any one of straight-chain or branched alkyl groups from C1 to C12.

2. The extractant according to claim 1, characterized in that, R1 and R2 may be the same or different, but are preferably the same; Preferably, the benzene ring-containing dialkyl phosphate includes any one or a combination of at least two of the following: di(4-methyl)phenyl phosphate, di(4-ethyl)phenyl phosphate, di(4-propyl)phenyl phosphate, di(4-butyl)phenyl phosphate, di(4-pentyl)phenyl phosphate, di(4-hexyl)phenyl phosphate, di(4-heptyl)phenyl phosphate, di(4-octyl)phenyl phosphate, di(4-nonyl)phenyl phosphate, di(4-decyl)phenyl phosphate, di(4-undecyl)phenyl phosphate, or di(4-dodecyl)phenyl phosphate.

3. An extraction system, characterized in that, The extraction system includes the extractant as described in claim 1 or 2.

4. The extraction system according to claim 3, characterized in that, The extraction system also includes a diluent; Preferably, the diluent comprises any one or a combination of at least two of kerosene, aromatic hydrocarbons, or aliphatic hydrocarbons; Preferably, the volume percentage of the extractant in the extraction system is 5-50 vol%.

5. The extraction system according to claim 3 or 4, characterized in that, The extraction system also includes a phase modifier; Preferably, in the extraction system, the phase modifier includes a non-water-soluble alcohol or a trialkyl phosphate ester; Preferably, the volume percentage of the phase modifier in the extraction system is 1-10 vol%. Preferably, the extraction system comprises, by volume percentage: 5-50 vol% extractant, 1-10 vol% phase modifier, and the remainder being diluent.

6. The use of an extractant according to claim 1 or 2 in the separation, extraction or purification of metals.

7. The application according to claim 6, characterized in that, The metal includes any one or a combination of at least two of calcium, manganese, nickel, cobalt, magnesium, zinc, or copper.

8. An extraction method for calcium, characterized in that, The extraction method includes the following steps: (1) The calcium-containing liquid is extracted using the extraction system described in any one of claims 3-5. After separation, a calcium-loaded organic phase and raffinate are obtained. (2) The calcium-loaded organic phase is back-extracted to obtain a calcium-enriched back-extracting solution.

9. The extraction method according to claim 8, characterized in that, The calcium ion concentration in the calcium-containing liquid in step (1) is 0.0001-1 g / L; Preferably, the pH of the calcium-containing solution in step (1) is 1-5, and more preferably 1-3; Preferably, the volume ratio of the extraction system in step (1) to the calcium-containing liquid is (1-500):100; Preferably, the extraction in step (1) is a multi-stage countercurrent extraction; Preferably, the number of stages in the multi-stage countercurrent extraction is 2-5 stages.

10. The extraction method according to claim 8 or 9, characterized in that, The back-extraction reagent used in step (2) includes an HCl solution with a concentration of 4-6 mol / L; Preferably, the volume ratio of the back-extraction reagent to the calcium-loaded organic phase is 1:(5-20); Preferably, the back-extraction in step (2) is a multi-stage countercurrent back-extraction; Preferably, the number of stages in the multi-stage countercurrent back-extraction is 2-3 stages.

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