Process for the separation of nickel and magnesium and use thereof

Abstract

This invention provides a method for separating nickel and magnesium and its application. The separation method includes the following steps: (1) preparing a high-purity extractant and a diluent into an extractable organic phase with a certain volume fraction, and then subjecting the extractable organic phase to a saponification reaction with an alkaline compound to obtain a saponified organic phase; the extractant contains a specific carboxylic acid compound; (2) mixing, extracting, and separating the saponified organic phase obtained in step (1) into a nickel-magnesium feed solution to obtain a loaded organic phase and a raffinate aqueous phase; (3) washing the loaded organic phase with a detergent to remove magnesium ions impurities extracted or entrained, to obtain a washed loaded organic phase and a washing residue; (4) back-extracting the washed loaded organic phase obtained in step (3) with a back-extraction agent to obtain a metal ion enrichment solution and a regenerated organic phase; the entire separation process is simple to operate, has low acid consumption, fast phase separation, and is environmentally friendly; the separation method has a good separation effect on nickel and magnesium, a high separation coefficient, and the extraction reagent used has low water solubility, is stable, and can be recycled after regeneration, which is beneficial to reducing separation costs and is suitable for large-scale application.

Description

Technical Field

[0001] This invention belongs to the field of metal ion separation and purification technology, specifically relating to a method for separating nickel and magnesium and its application. Background Technology

[0002] Currently, new energy vehicles have achieved significant results in improving urban pollution and effectively reducing carbon emissions in terms of environmental protection. The rapid development of electric vehicles is attributed to the upgrading of power battery technology. Nickel, as an essential metal material in power battery production, is poised for a new revolution in power batteries with advancements in nickel utilization technology. Some nickel comes from laterite nickel ore and nickel sulfide ore, while some comes from the recycling of spent lithium batteries. Surveys indicate that over one billion lithium-ion batteries are discarded worldwide each year. The reprocessing of spent lithium-ion batteries and the separation and recycling of their various metals constitute an important resource regeneration effort. Furthermore, the heavy metals such as nickel, cobalt, and manganese contained in spent batteries pose serious environmental hazards. Therefore, recycling and reusing the precious metals contained in spent lithium batteries can both recycle resources and protect the environment, offering promising environmental and market prospects.

[0003] The main methods for recovering precious metals such as nickel from spent lithium-ion batteries are pyrometallurgy and hydrometallurgy. Pyrometallurgy is limited in application due to problems such as poor operating conditions, high operating temperatures, high energy consumption, severe air pollution, and complex start-up and shutdown processes. Hydrometallurgy, on the other hand, can directly produce finished products, has low cost, and high automation, making it a promising area for application. Hydrometallurgical methods mainly include chemical precipitation, membrane separation technology, ion exchange, adsorption, and solvent extraction.

[0004] CN102814058A discloses a method for separating, enriching, and purifying nickel and magnesium using adsorption materials. The method involves adjusting the pH of a solution containing nickel and magnesium ions to 1.0–5.5 to obtain an acid leaching solution. This acid leaching solution is then mixed with a heavy metal adsorption material in an adsorption column. The heavy metal adsorption material adsorbs nickel ions from the acid leaching solution, while magnesium ions remain in the solution. The heavy metal adsorption material is then washed with a 5–30% sulfuric acid solution to perform desorption, yielding a nickel-containing desorption solution and the desorbed heavy metal adsorption material. Electrowinning with the nickel-containing desorption solution yields nickel metal or nickel metal powder. The desorbed heavy metal adsorption material can be repeatedly recycled. This method has the advantages of convenient operation and simple equipment. However, the production process of the heavy metal adsorption material is complex. After multiple uses, the capacity and adsorption efficiency of the heavy metal adsorption material decrease, and it is susceptible to the influence of insoluble substances and impurities in the system, requiring replacement of the heavy metal adsorption material and further processing after replacement.

[0005] CN108569723A discloses a method for treating nickel-containing electroplating wastewater using chemical precipitation. The wastewater enters a reactor, and sodium sulfide and calcium hydroxide are added simultaneously. The mixture is stirred until fully reacted, then stirring is stopped after 20 minutes. After sedimentation in the reactor for 5 days, the supernatant is discharged into the next reactor. Calcium hydroxide is added again for further reaction, and after standing for 1 day, the supernatant is discharged through a drain valve. This method removes nickel by precipitation, achieving a removal rate of up to 99%. It effectively treats wastewater and improves nickel recovery. It has the advantages of simple process and low operating cost. However, this method requires large equipment, has limited processing capacity, and a long processing time. Impurities carried by the nickel precipitate also hinder separation. Furthermore, the nickel precipitate sludge requires dewatering and reprocessing to prevent secondary pollution.

[0006] Solvent extraction has the advantages of high efficiency, fine separation, energy saving and low carbon emissions, continuous and automated operation, and easy industrialization, making it a current research hotspot for recovering precious metals such as nickel from waste batteries.

[0007] CN110066925A discloses a method for recovering valuable metals from waste nickel-cobalt-manganese ternary lithium batteries. The method involves using P204 to extract and remove impurities from the battery solution, followed by back-extraction to obtain a back-extraction solution containing manganese sulfate and a raffinate containing Co, Ni, and Li ions. After removing Cu from the back-extraction solution, the solution is evaporated, concentrated, and crystallized to obtain manganese sulfate. Co is extracted from the raffinate using saponified P507, and back-extracted to obtain a cobalt sulfate solution. Mg is then removed from the raffinate using C272, and finally Ni is extracted from the raffinate using P507, with back-extraction yielding a nickel sulfate solution. The Ca and Mg contents are then detected, and sodium fluoride or potassium fluoride is added to precipitate Ca and Mg, which are then filtered out. This process is complex, and the use of precipitation to remove impurity metal ions such as Ca and Mg can easily lead to the loss of valuable metals due to entrainment.

[0008] Therefore, developing a method for separating nickel and magnesium with low acid consumption, high extraction efficiency, and low cost to improve the separation efficiency and recovery rate of nickel and magnesium has become a key research focus in this field. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide a method for separating nickel and magnesium and its application. The separation method utilizes a carboxylic acid compound CPH88 with a specific structure as an extractant. Through a combination of extraction and other methods, nickel and magnesium in a nickel-magnesium feed solution are successfully separated. The entire separation process has advantages such as simple operation, environmental friendliness, and low cost.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] In a first aspect, the present invention provides a method for separating nickel and magnesium, the method comprising the following steps:

[0012] (1) The extracting organic phase is saponified with an alkaline compound to obtain a saponified organic phase. The saponified organic phase can control the pH value of the aqueous phase of the extraction system within a suitable range so as to better separate nickel and magnesium metal ions.

[0013] The extracted organic phase contains a carboxylic acid compound CPH88 with the structure shown in Formula I:

[0014]

[0015] Among them, C8H 17 All are straight-chain alkane groups containing branches;

[0016] (2) The saponified organic phase obtained in step (1) is mixed and extracted with nickel and magnesium materials, clarified and separated into layers to obtain a loaded organic phase and a raffinate aqueous phase; the raffinate aqueous phase contains magnesium ions, and this step separates nickel and magnesium.

[0017] (3) The loaded organic phase is washed with detergent to remove magnesium ions that were extracted or entrained, and the washed loaded organic phase and washing residue are obtained. After removing magnesium ions that were entrained and extracted during the extraction process, the back-extraction section can reach a nickel ion solution with higher purity.

[0018] (4) The washed and loaded organic phase obtained in step (3) is back-extracted using a back-extraction agent to obtain a metal ion enrichment solution and a regenerated organic phase. On the one hand, a metal ion enrichment solution containing nickel ions is obtained, and on the other hand, the organic phase is regenerated, which is beneficial for recycling and reducing costs. The entire separation process has low acid consumption, simple operation, low cost, and good separation effect of nickel and magnesium.

[0019] Preferably, the extracted organic phase further includes a diluent.

[0020] Preferably, the diluent comprises any one or a combination of at least two of the following: diluent Escaid 110, solvent oil, toluene, hexane, heptane, dodecane, or kerosene; more preferably, Escaid 110 and / or dodecane.

[0021] Preferably, the dodecane is n-dodecane.

[0022] Preferably, the high-purity extractant accounts for 5% to 30% of the volume percentage of the extracted organic phase, for example, 5%, 6%, 8%, 10%, 12%, 15%, 18%, 20%, 21%, 23%, 25%, 27%, or 30%, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0023] Preferably, the alkaline compound in step (1) includes an inorganic base.

[0024] Preferably, the inorganic base includes any one or a combination of at least two of sodium hydroxide, magnesium oxide, potassium hydroxide, or ammonia water.

[0025] Preferably, the volume ratio of the saponified organic phase and the nickel-magnesium liquid in step (2) is 1:(0.1~10), for example, 1:0.1, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9 or 1:9.5, etc.

[0026] As a preferred technical solution of the present invention, the volume ratio of the saponified organic phase and the nickel-magnesium liquid in step (2) of the present invention is 1:(0.1~10). If the volume ratio is too large, the volume ratio of the nickel-magnesium liquid will be too small, resulting in the magnesium-containing extract being entrained or magnesium ions being extracted, which will affect the concentration of metal enrichment in the later stage. If the volume ratio is too small, the extraction capacity of the organic phase will be insufficient, resulting in the incomplete extraction of nickel ions and difficulty in mixing evenly.

[0027] Preferably, the pH value of the raffinate phase in step (2) is 5.0 to 7.8, for example 5.0, 5.8, 6.0, 6.4, 6.7, 7.0, 7.1, 7.2 or 7.7, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0028] As a preferred technical solution of the present invention, the pH value of the raffinate aqueous phase is 5.0 to 7.8. If the pH value is too low, the nickel extraction rate is low; if the pH value is too high, more magnesium is extracted into the organic phase in the nickel-magnesium feed solution, which increases the washing cost.

[0029] Preferably, the extraction in step (2) is carried out under stirring conditions.

[0030] Preferably, the stirring speed in step (2) is 100-800 rpm / min, such as 120 rpm / min, 140 rpm / min, 150 rpm / min, 300 rpm / min, 500 rpm / min, 600 rpm / min, 700 rpm / min or 790 rpm / min, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0031] Preferably, the stirring and mixing time is 3 to 30 minutes, such as 3 minutes, 5 minutes, 8 minutes, 10 minutes, 12 minutes, 15 minutes, 18 minutes, 20 minutes, 22 minutes, 25 minutes, or 29 minutes, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0032] Preferably, the extraction in step (2) is a multi-stage countercurrent fractionation extraction.

[0033] Preferably, the number of extraction stages in the multi-stage countercurrent fractionation extraction is 2-30 stages, such as 3 stages, 4 stages, 5 stages, 6 stages, 7 stages, 8 stages, 9 stages, 12 stages, 15 stages, 17 stages, 18 stages, 19 stages, 22 stages, 25 stages, 27 stages, or 29 stages, as well as specific point values ​​between the above-mentioned point values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the range.

[0034] Preferably, the stratification time in step (2) is 2 to 50 minutes, for example, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes or 45 minutes, and specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific point values ​​included in the range.

[0035] Preferably, the washing step of the supported organic phase obtained in step (3) is performed to remove impurity magnesium ions;

[0036] Preferably, the number of washing stages is 2 to 20, such as 3, 4, 5, 6, 7, 10, 12, 14, 16, 18 or 19 stages, etc.

[0037] Preferably, the washing includes washing with inorganic acid and / or acidified water, ultrapure water, or nickel sulfate solution;

[0038] Preferably, the pH value of the inorganic acid and / or acidified water is 0.1 to 2, for example 0.1, 0.5, 0.7, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8 or 1.9, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0039] Preferably, the ultrapure water is obtained from primary water reverse osmosis;

[0040] Preferably, the nickel sulfate solution has a concentration of 0.5–20 g / L; for example, 0.5 g / L, 1 g / L, 3 g / L, 5 g / L, 12 g / L, 13 g / L, 15 g / L, 17 g / L, 18 g / L, or 19 g / L, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0041] Preferably, the stripping agent in step (4) comprises an inorganic acid.

[0042] Preferably, the inorganic acid includes any one or a combination of at least two of hydrochloric acid, nitric acid, or sulfuric acid.

[0043] Preferably, the concentration of inorganic acid in the stripping agent is 0.5–4 mol / L, for example 0.6 mol / L, 0.9 mol / L, 1.2 mol / L, 1.5 mol / L, 1.8 mol / L, 2.1 mol / L, 2.4 mol / L, 2.7 mol / L, 3 mol / L, 3.3 mol / L, 3.6 mol / L, or 3.9 mol / L, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0044] Preferably, the number of stages of back-extraction in step (4) is 1 to 10, such as 2, 3, 4, 5, 6, 8 or 9 stages.

[0045] Preferably, the volume ratio of the stripping agent to the supported organic phase is 1:(0.1-15), for example, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5, 1:11, 1:13, 1:14, or 1:15, etc.

[0046] Preferably, the reaction equipment is a mixing and clarification tank, a packed extraction tower, or a spray extraction tower; more preferably, the reaction equipment is a mixing and clarification tank.

[0047] Preferably, the separation method specifically includes the following steps:

[0048] (1) The extracted organic phase is subjected to a saponification reaction with an alkaline compound to obtain a saponified organic phase; the extracted organic phase contains a diluent and a carboxylic acid compound CPH88 containing the structure shown in Formula I:

[0049]

[0050] Among them, C8H 17All are straight-chain alkane groups containing branches.

[0051] (2) The saponified organic phase obtained in step (1) is extracted with nickel-magnesium feed solution at a volume ratio of 1:(0.1-10), and the layers are separated to obtain a loaded organic phase containing nickel ions and a raffinate aqueous phase containing magnesium ions with a pH value of 5.0-7.8.

[0052] (3) After washing the loaded organic phase obtained in step (2) with detergent, the washed loaded organic phase and washing residue are obtained.

[0053] (4) Back-extraction is performed using a back-extraction agent to obtain a metal ion enrichment solution containing nickel ions and a regenerated organic phase; the volume ratio of the back-extraction agent to the supported organic phase is 1:(0.1-15).

[0054] In a second aspect, the present invention provides an application of the separation method as described in the first aspect, wherein the application is for separating nickel and magnesium from battery recycling waste liquid.

[0055] Preferably, the battery is a ternary nickel-cobalt-manganese ion battery.

[0056] Thirdly, the present invention provides the application of an extraction reagent comprising a carboxylic acid compound having the structure shown in Formula I in the separation of nickel and magnesium.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] The method for separating nickel and magnesium provided by this invention first involves saponifying an extractable organic phase containing a carboxylic acid compound with a specific structure to obtain a saponified organic phase. Then, the saponified organic phase is used to extract the nickel and magnesium feed solution to separate the nickel and magnesium. Finally, the extracted organic phase containing nickel is back-extracted to obtain a regenerated organic phase and a metal ion enrichment solution. The entire process is simple to operate, has low acid consumption, and is environmentally friendly. Furthermore, the separation method provided by this invention not only has good ion separation effect, but also uses extraction reagents with low solubility and stability, which can be recycled after regeneration, thus reducing costs and enabling large-scale industrial applications. Detailed Implementation

[0059] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0060] Preparation Example 1

[0061] A carboxylic acid compound with the following structure:

[0062]

[0063] Among them, C8H17 All are straight-chain alkane groups containing branches.

[0064] The preparation method includes the following steps:

[0065]

[0066] 20 g of pyridine dicarboxylic acid was added to a 500 mL round-bottom flask. While stirring at room temperature, 200 mL of thionyl chloride was slowly added dropwise. A rise in temperature indicated the reaction had occurred. After the addition was complete, the mixture was refluxed for 30 minutes, and excess thionyl chloride was removed by distillation. Subsequently, 200 mL of dichloromethane and 24 g of triethylamine (approximately 2 eq) were added to the flask, followed by dropwise addition of 28.9 g of diisooctylamine (1 eq). The reaction was allowed to proceed at room temperature for 1 hour, after which the reaction was stopped. The product was washed twice with hydrochloric acid (pH=1), then once with water, dried over sodium sulfate, and the solvent was evaporated to obtain 34.6 g of the target product.

[0067] Characterization data: 13 C NMR(101MHz, CDCl3)δ167.1(s),149.3(s),144.2(s),140.7(s),127.6(m),51.5(m), 32.31–31.38(m),29.37(m),27.2(m),24.3(m),14.1(d,J=4.4Hz); 11.3(d,J=5.9Hz); 1 H NMR (400MHz, CDCl3) δ12.1(1H), 8.79(1H), 8.68(1H), 8.49(1H), 2.72(4H), 1.92(2H), 1.27(16H), 0.89(6H), 0.85(6H); MS: 390.3

[0068] Preparation Example 2

[0069] The preparation method includes the following steps:

[0070] 20 g of pyridine dicarboxylic acid was added to a 500 mL round-bottom flask. While stirring at room temperature, 200 mL of thionyl chloride was slowly added dropwise. A rise in temperature indicated the reaction had occurred. After the addition was complete, the mixture was refluxed for 30 minutes, and excess thionyl chloride was removed by distillation. Subsequently, 200 mL of dichloromethane and 24 g of triethylamine (approximately 2 eq) were added to the flask, followed by dropwise addition of 28.9 g of diisooctylamine (1 eq). The reaction was stopped after reacting at room temperature for 1 hour. The product was washed twice with hydrochloric acid (pH=1), then once with water, dried over sodium sulfate, and the solvent was evaporated to obtain 36.6 g of the target product.

[0071] Characterization data: 13C NMR(101MHz, CDCl3)δ168.1(s),150.3(s),146.2(s),126.6(m),140.7(s),45.5( m),32.31–31.38(m),29.37(m),27.2(m),22.3(d,J=5.9Hz),14.02(d,J=4.4Hz); 1 H NMR (400MHz, CDCl3) δ12.1(1H), 8.81(1H), 8.70(1H), 8.51(1H), 2.94(4H), 1.52(4H), 1.27(20H), 0.85(6H); MS: 390.3

[0072] Example 1

[0073] A method for separating nickel and magnesium, the specific steps of which are as follows:

[0074] (1) The carboxylic acid compound obtained in Preparation Example 1 was dissolved in diluent Escaid 110 so that the volume percentage of high-purity extractant in Escaid 110 was 25%, and then a 10 mol / L NaOH solution was added and mixed to obtain a saponified organic phase with a saponification degree of 41%, and the saponified organic phase was used as an organic phase system.

[0075] (2) The nickel-magnesium liquid is used as an aqueous phase system (containing 2.0 g / L nickel, 18 g / L magnesium, pH value 5.3, specifically derived from intermediate material in nickel purification of waste lithium-ion battery cathode material leaching solution), and flows into the mixing and clarifying tank from both ends of the saponified organic phase obtained in step (1) (the flow ratio of saponified organic phase and nickel-magnesium liquid is 1:5). The mixing speed is kept at 600 rpm / min, the mixing time is 15 min, the temperature is 25℃, and multi-stage countercurrent fractionation extraction is carried out with 10 extraction stages. The phases are allowed to stand for 22 min to separate, and the layers are separated to obtain an organic phase loaded with nickel ions and an outlet aqueous phase containing magnesium ions with pH value of 7 (i.e., raffinate aqueous phase).

[0076] (3) The loaded organic phase obtained in step (2) is washed with sulfuric acid solution with pH value of 1 in 12 stages of countercurrent washing, and then back-extracted with sulfuric acid with a concentration of 2 mol / L, with a back-extraction stage of 6 stages; the flow ratio of the washing agent sulfuric acid solution to the loaded organic phase is 1:0.2, and the flow ratio of the 2 mol / L sulfuric acid to the loaded organic phase is 1:10, to obtain a metal ion enrichment solution and a regenerated organic phase.

[0077] Example 2

[0078] A method for separating nickel and magnesium, the specific steps of which are as follows:

[0079] (1) The carboxylic acid compound obtained in Preparation Example 1 was dissolved in Escaid 110, the volume percentage of CPH88 in Escaid 110 was 25%, and then a 10 mol / L NaOH solution was added and mixed to obtain a saponified organic phase with a saponification degree of 30%, and the saponified organic phase was used as the organic phase system.

[0080] (2) The nickel-magnesium solution is used as an aqueous phase system (containing 2.0 g / L nickel, 18 g / L magnesium, and pH 5.3, specifically derived from intermediate materials in the nickel purification of waste lithium-ion battery cathode material leaching solution), and flows into the extractor from both ends of the extractor with the saponified organic phase described in step (1) (the volume ratio of the saponified organic phase to the nickel-magnesium solution is 1:4). The mixture is stirred at a speed of 760 rpm / min for 5 min and at a temperature of 25°C. Multi-stage countercurrent fractionation extraction is performed with 12 extraction stages. The mixture is allowed to stand for 10 min and then separated into layers to obtain an organic phase loaded with nickel ions and a raffinate aqueous phase containing magnesium ions with a pH of 7.2 to 7.4.

[0081] (3) The loaded organic phase obtained in step (2) is washed with sulfuric acid with a pH of 0.9 in 18 stages of countercurrent washing, and then back-extracted with sulfuric acid with a concentration of 2 mol / L. The back-extraction stage is 6 stages. The flow ratio of the washing sulfuric acid to the loaded organic phase is 1:0.25, and the flow ratio of the 2 mol / L sulfuric acid to the loaded organic phase is 1:10, so as to obtain a metal ion enrichment solution and a regenerated organic phase.

[0082] Example 3

[0083] A method for separating nickel and magnesium, the specific steps of which are as follows:

[0084] (1) The carboxylic acid compound obtained in Preparation Example 1 was dissolved in dodecane, the volume percentage of the carboxylic acid compound in dodecane was 25%, and then an ammonia solution with a concentration of 11 mol / L was added and mixed to obtain a saponified organic phase with a saponification degree of 30%, and the saponified organic phase was used as the organic phase system.

[0085] (2) The nickel-magnesium solution is used as an aqueous phase system (containing 1.70 g / L of nickel, 19 g / L of magnesium, and a pH value of 5.20, specifically derived from intermediate materials in the nickel purification of waste lithium-ion battery cathode material leaching solution), and flows into the extractor from both ends of the saponified organic phase described in step (1) (the volume ratio of the saponified organic phase and the nickel-magnesium solution is 1:4.5). The mixture is stirred at a speed of 800 rpm / min for 5 min, and the temperature is 25°C. Multi-stage countercurrent fractionation extraction is performed with 6 extraction stages. The separation is clarified and separated for 10 min to obtain an organic phase loaded with nickel ions and a raffinate aqueous phase containing magnesium ions with a pH value of 6.8.

[0086] (3) The loaded organic phase obtained in step (2) is washed with sulfuric acid with a pH of 1.0 in 8 stages of countercurrent washing, and then back-extracted with sulfuric acid with a concentration of 2.5 mol / L for 4 times; the flow ratio of the washing sulfuric acid to the loaded organic phase is 1:5, and the flow ratio of the 3 mol / L sulfuric acid to the loaded organic phase is 1:10, so as to obtain a metal ion negative electrode solution and a regenerated organic phase.

[0087] Example 4

[0088] A method for separating nickel and magnesium differs from Example 1 only in that the sulfuric acid detergent in step (3) is replaced with a 1.0 g / L nickel sulfate solution, while the amounts of other components and experimental conditions are the same as in Example 1.

[0089] Comparative Example 1

[0090] A method for separating nickel and magnesium differs from Example 1 only in that the carboxylic acid compound in step (1) is replaced with an equal amount of extractant P507 (2-ethylhexylphosphonic acid mono-2-ethylhexyl ester), while the amounts of other components and experimental conditions are the same as in Example 1.

[0091] Comparative Example 2

[0092] A method for separating nickel and magnesium differs from Example 1 only in that the carboxylic acid compound in step (1) is replaced with an equal amount of extractant C272 (bis-(2,4,4-trimethyl)pentylphosphonic acid), while the amounts of other components and experimental conditions are the same as in Example 1.

[0093] Performance testing:

[0094] The saponification ratio refers to the proportion of alkali metal NH in the extractant. + 4 and / or Na + The proportion of hydrogen ions to the original amount, i.e., η = (Vbase × Cbase) / (Vexisting × Cexisting) × 100% (1)

[0095] In formula (1), Vbase is the volume of the aqueous solution of the added base in mL, Cbase is the concentration of the added base in the aqueous solution in mol / L, Vuse is the volume of the organic phase in mL, and Cuse is the concentration of the extractant in the organic phase in mol / L.

[0096] In this embodiment of the invention, the metal ion content in the aqueous phase is determined by inductively coupled plasma optical emission spectrometry (ICP-OES), and then the metal ion content in the organic phase is obtained by the difference method.

[0097] The raffinate aqueous phase and metal ion enrichment solution obtained by step (2) of the extraction method described in Examples 1-4 and Comparative Examples 1-2 were tested according to the above test method, and the results are shown in Table 1.

[0098] Table 1

[0099] Purity (%) of nickel sulfate after back-extraction Nickel content in the aqueous phase at the outlet (mg / L) Example 1 99.9 0.50 Example 2 99.9 0.45 Example 3 99.9 0.40 Example 4 99.9 0.50 Comparative Example 1 98.7 4.0 Comparative Example 2 99.5 3.3

[0100] As can be seen from the data in Table 1, the method for separating nickel and magnesium provided by this invention has a better separation effect compared with the prior art.

[0101] The applicant declares that this invention illustrates a method for separating nickel and magnesium and its application through the above embodiments, but this invention is not limited to the above process steps, that is, it does not mean that this invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials used in this invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

Claims

1. A method for separating nickel and magnesium, characterized in that, The separation method includes the following steps: (1) A high-purity extractant and a diluent are prepared into an extractable organic phase with a certain volume fraction, wherein the high-purity extractant accounts for 5-30% of the volume percentage of the extractable organic phase. Then, the extractable organic phase is subjected to a saponification reaction with an alkaline compound to obtain a saponified organic phase. The high-purity extractant is a carboxylic acid compound with the structure shown in Formula I: Formula I Among them, C8H 17 All are straight-chain alkane groups containing branches; (2) The saponified organic phase obtained in step (1) is mixed with the nickel-magnesium feed solution for extraction, clarification and phase separation to obtain a loaded organic phase and a raffinate aqueous phase. The loaded organic phase contains metallic nickel ions. The volume ratio of the saponified organic phase to the nickel-magnesium feed solution is 1:(0.1~10). The equilibrium pH value of the raffinate aqueous phase is 5.0~7.

8. (3) The loaded organic phase is washed with detergent to remove magnesium ions, which are impurities from extraction or entrainment, to obtain the washed loaded organic phase and washing residue. The washing residue is then incorporated into the raffinate aqueous phase. (4) The washed and loaded organic phase obtained in step (3) is back-extracted with a back-extraction agent to obtain a metal ion enrichment solution and a regenerated organic phase; The high-purity extractant is prepared by the following method: ； Add 20 g of pyridine dicarboxylic acid to a 500 mL round-bottom flask and slowly add 200 mL of thionyl chloride dropwise while stirring at room temperature. The temperature rise indicates that the reaction has occurred. After the addition is complete, reflux the reaction for 30 minutes and remove excess thionyl chloride by distillation. Then add 200 mL of dichloromethane and 24 g of triethylamine to the flask and add 28.9 g of diisooctylamine dropwise. After reacting at room temperature for 1 hour, stop the reaction. Wash twice with hydrochloric acid at pH=1, then wash once with water, dry with sodium sulfate, and evaporate the solvent to obtain the target product.

2. The separation method according to claim 1, characterized in that, The extracted organic phase also includes a diluent.

3. The separation method according to claim 2, characterized in that, The diluent includes any one or a combination of at least two of the following: diluent Escaid 110, solvent oil, toluene, hexane, heptane, dodecane, or kerosene.

4. The separation method according to claim 3, characterized in that, The diluent is Escaid 110 and / or dodecane.

5. The separation method according to claim 4, characterized in that, The dodecane in question is n-dodecane.

6. The separation method according to claim 1, characterized in that, The alkaline compound in step (1) includes inorganic bases.

7. The separation method according to claim 6, characterized in that, The inorganic base includes any one or a combination of at least two of sodium hydroxide, potassium hydroxide, or ammonia water.

8. The separation method according to claim 6, characterized in that, The concentration of the alkaline compound is between 2 and 14 mol / L.

9. The separation method according to claim 1, characterized in that, The mixing in step (2) is carried out under stirring conditions.

10. The separation method according to claim 9, characterized in that, The stirring speed is 100~800 rpm / min.

11. The separation method according to claim 1, characterized in that, The mixing time is 3 to 30 minutes.

12. The separation method according to claim 1, characterized in that, The extraction method described in step (2) is multi-stage countercurrent fractionation extraction.

13. The separation method according to claim 12, characterized in that, The number of extraction stages in the multi-stage countercurrent fractionation extraction is 2 to 30.

14. The separation method according to claim 1, characterized in that, The extraction in step (2) is carried out at a temperature of 10~50℃.

15. The separation method according to claim 1, characterized in that, The clarification and stratification time in step (2) is 2 to 50 minutes.

16. The separation method according to claim 1, characterized in that, The nickel-magnesium solution in step (2) is a chloride salt system or a sulfate salt system.

17. The separation method according to claim 16, characterized in that, The nickel-magnesium solution is a sulfate system.

18. The separation method according to claim 1, characterized in that, In step (2), the nickel-magnesium ratio of the nickel-magnesium slurry is 1:(0.5~20).

19. The separation method according to claim 1, characterized in that, The washing stages in step (3) are 2 to 20.

20. The separation method according to claim 1, characterized in that, The washing in step (3) includes washing with inorganic acid and / or acidified water, ultrapure water, or nickel sulfate solution.

21. The separation method according to claim 20, characterized in that, The inorganic acid and / or acidified water have a pH value of 0.1 to 2.

22. The separation method according to claim 20, characterized in that, The nickel sulfate solution is 0.5~20g / L.

23. The separation method according to claim 20, characterized in that, The ultrapure water mentioned is obtained by reverse osmosis filtration of deionized water.

24. The separation method according to claim 1, characterized in that, The stripping agent includes inorganic acids.

25. The separation method according to claim 24, characterized in that, The volume ratio of the stripping agent to the supported organic phase is 1:(0.1~15).

26. The separation method according to claim 24, characterized in that, The inorganic acid includes any one or a combination of at least two of hydrochloric acid, nitric acid, or sulfuric acid.

27. The separation method according to claim 24, characterized in that, The concentration of inorganic acid in the stripping agent is 0.5~4 mol / L.

28. The separation method according to claim 27, characterized in that, The concentration of the stripping agent is 2 mol / L.

29. The separation method according to claim 1, characterized in that, The back-extraction process has 1 to 10 stages.

30. The separation method according to claim 1, characterized in that, The separation method specifically includes the following steps: (1) The extracted organic phase is subjected to a saponification reaction with an alkaline compound to obtain a saponified organic phase with a saponification degree of 1-50%; the extracted organic phase contains a diluent and a carboxylic acid compound CPH88 with the structure shown in Formula I: Formula I; Among them, the branch chain C8H 17 All are straight-chain alkane groups; (2) The saponified organic phase obtained in step (1) is mixed with a nickel-magnesium feed solution with a pH of 2 to 8 at a volume ratio of 1:(0.1 to 10) and extracted. The mixture is then clarified and separated to obtain a loaded organic phase containing nickel ions and a raffinate aqueous phase containing magnesium ions. (3) The loaded organic phase is washed with detergent to remove magnesium ions impurities from extraction or entrainment, and the washed loaded organic phase and washing residue are obtained. The washing residue is added to the extraction residue. (4) The washed and loaded organic phase obtained in step (3) is back-extracted with a back-extraction agent to obtain a metal ion enrichment solution and a regenerated organic phase.

31. An application of the separation method as described in any one of claims 1 to 30, characterized in that, The application is for separating nickel and magnesium in a nickel-cobalt-manganese metal recovery system for batteries.

32. The application according to claim 31, characterized in that, The battery is a ternary nickel-cobalt-manganese battery.

33. An application of the separation method as described in any one of claims 1 to 30, characterized in that, The application is the use of extraction reagents containing carboxylic acid compounds having the structure shown in Formula I in the separation of nickel and magnesium.

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