A method for synergistic extraction and directional removal of zinc from complex multi-metallic ion solutions

Abstract

The application discloses a method for cooperatively extracting and directionally removing zinc from a complex multi-metal ion solution and relates to the technical field of non-ferrous metallurgy. The method comprises the following steps: mixing P204 and P507, adding a diluent, and preparing a cooperative extraction organic phase; taking the complex multi-metal ion solution as an extraction feed liquid, and adjusting the pH value to 1.9-2.6; through multi-stage countercurrent extraction, the water phase equilibrium pH value is controlled to be 1.9-2.6, and an organic phase loaded with zinc is obtained; and the organic phase loaded with zinc is subjected to pickling and reverse extraction, and a zinc-rich solution is obtained. Through the method of cooperative solvent extraction, the high-selectivity extraction of zinc is realized, and the loss of manganese, nickel and cobalt in the complex multi-metal ion solution is reduced.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal metallurgy technology, specifically to a method for the synergistic extraction and targeted removal of zinc from complex polymetallic ion solutions. Background Technology

[0002] With the global transformation towards a low-carbon economy and the explosive growth of the new energy vehicle industry, the demand for key battery metals such as nickel (Ni), cobalt (Co), and manganese (Mn) has surged. Currently, deep-sea polymetallic nodules are a potential alternative mineral for nickel and cobalt resources. Similar to terrestrial sulfide nickel ores and laterite nickel ores, deep-sea polymetallic nodule leachates often contain impurities such as zinc, iron, aluminum, calcium, and magnesium, in addition to the target metals manganese, nickel, cobalt, and copper. These leachates are collectively referred to as complex polymetallic ion solutions.

[0003] Zinc (Zn), a transition metal with chemical properties similar to nickel and cobalt, can severely interfere with the subsequent separation and purification of nickel and cobalt. Without thorough removal, zinc will accompany the nickel and cobalt into the final product, significantly impacting the purity and electrochemical performance of battery-grade nickel sulfate / cobalt sulfate. For example, in the preparation of precursors for ternary lithium-ion battery cathode materials, zinc impurities reduce the material's cycle stability and capacity retention.

[0004] It is difficult to achieve highly selective extraction of zinc from complex polymetallic ion solutions using existing technologies. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing a method for the targeted removal of zinc from complex polymetallic ion solutions through synergistic extraction. Utilizing an organophosphate synergistic extraction system, this method efficiently and selectively removes and recovers zinc from deep-sea polymetallic nodule leachates or other complex polymetallic ion sulfuric acid solutions. It is particularly suitable for treating nickel-cobalt leachates containing zinc impurities under a high-manganese background and can serve as a critical deep purification and impurity removal process before the production of battery-grade nickel-cobalt salt products.

[0006] Therefore, the present invention provides a method for the synergistic extraction and targeted removal of zinc from complex polymetallic ion solutions, comprising the following steps: Organic phase preparation: The extractant di(2-ethylhexyl) phosphate and the extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester were mixed, and a diluent was added to prepare a synergistic extraction organic phase; Feed solution control: The complex polymetallic ion solution is used as the extraction feed solution, and the pH value of the extraction feed solution is adjusted to 1.9~2.6; wherein, the complex polymetallic ion solution contains zinc ions, nickel ions, cobalt ions, manganese ions, magnesium ions and calcium ions; Synergistic extraction: The synergistic extraction organic phase is mixed with the extraction feed liquid and subjected to multi-stage countercurrent extraction to obtain a zinc-loaded organic phase; wherein, during the synergistic extraction process, the equilibrium pH of the aqueous phase is controlled at 1.9~2.6, so that zinc ions selectively enter the organic phase, while nickel, cobalt and manganese ions remain in the aqueous phase; Washing and back-extraction: The zinc-loaded organic phase is acid-washed and back-extracted to obtain a zinc-rich solution.

[0007] Furthermore, in the synergistic extraction organic phase, the volume ratio of the 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester to the di(2-ethylhexyl) phosphate ester is 1:1 to 6:1, and the total volume concentration of the extractant is 5% to 20%.

[0008] Furthermore, the diluent is selected from at least one of sulfonated kerosene, 260# solvent oil, or aviation kerosene; the co-extracting organic phase is subjected to saponification treatment.

[0009] Furthermore, in the complex multi-metal ion solution, the concentration of zinc ions is 0.05 g / L to 0.5 g / L, the concentration of nickel ions is 0.3 g / L to 1.5 g / L, the concentration of cobalt ions is 0.3 g / L to 1.5 g / L, the concentration of manganese ions is 15 g / L to 40 g / L, the concentration of magnesium ions is 1 g / L to 3 g / L, and the concentration of calcium ions is 0.1 g / L to 1 g / L.

[0010] Furthermore, the liquid conditioning includes adjusting the pH value to 1.9-2.6 using at least one of sodium hydroxide solution, calcium oxide emulsion, magnesium oxide emulsion, or ammonia water. The adjustment process is carried out at 20°C-50°C, and the stirring time is 20-60 minutes.

[0011] Furthermore, the synergistic extraction includes: a multi-stage countercurrent extraction stage of 2 to 6 stages, an O / A ratio of 3:1 to 1:3, a single-stage extraction contact time of 1 to 10 minutes, and an extraction temperature of 20°C to 40°C.

[0012] Furthermore, in the washing and back-extraction process, the acid washing uses a sulfuric acid solution with a concentration of 0.1 mol / L to 0.5 mol / L, the washing ratio O / A is 1:1 to 6:1, and the number of washing stages is 1 to 5.

[0013] Furthermore, in the washing and back-extraction process, the back-extraction uses a sulfuric acid solution with a concentration of 1.0 mol / L to 3.0 mol / L, the back-extraction ratio O / A is 1:1 to 6:1, and the number of back-extraction stages is 2 to 6.

[0014] Furthermore, through the aforementioned synergistic extraction, the extraction rate of zinc reaches over 95%, the extraction rate of manganese is less than 1%, the extraction rate of nickel is less than 1%, and the extraction rate of cobalt is less than 1%.

[0015] Furthermore, the pickling process reduces the loss rates of manganese, nickel, and cobalt to below 0.3%.

[0016] This invention achieves the selective separation of zinc and manganese-nickel-cobalt based on the differences in the partitioning behavior of metal ions between aqueous and organic phases. The specific principle is as follows: P204 has strong acidity; introducing it into the P507 system forms a mixed dimer, significantly improving the system's ability to release protons, thus lowering the effective extraction pH for zinc; the P507 molecule has significant steric hindrance, synergistically enhancing the extraction system's ability to selectively extract tetrahedral Zn. 2+ It maintains extremely high affinity, but is effective against Mn with octahedral coordination and large ionic radii. 2+ Ni 2+ Co 2+ This resulted in strong steric repulsion, which significantly increased the separation coefficient between zinc and manganese-nickel-cobalt.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: This invention provides a method for the targeted removal of zinc from complex polymetallic ion solutions through synergistic extraction. Based on a synergistic solvent extraction system of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (P507) and di(2-ethylhexyl) phosphate (P204), it achieves highly selective extraction of zinc, with an extraction rate exceeding 95%, while the co-extraction losses of manganese, nickel, and cobalt are all less than 1%. This invention significantly improves the selectivity of zinc through synergistic solvent extraction, minimizing the loss of valuable metals such as manganese, nickel, and cobalt. Detailed Implementation

[0018] To better understand the above technical solutions, the technical solutions of the embodiments of this application will be described in detail below through specific embodiments. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0019] This invention provides a method for the synergistic extraction and targeted removal of zinc from complex polymetallic ion solutions, comprising the following steps: Organic phase preparation: The extractant di(2-ethylhexyl) phosphate and the extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester were mixed, and a diluent was added to prepare a synergistic extraction organic phase; Feed solution control: The complex polymetallic ion solution is used as the extraction feed solution, and the pH value of the extraction feed solution is adjusted to 1.9~2.6; wherein, the complex polymetallic ion solution contains zinc ions, nickel ions, cobalt ions, manganese ions, magnesium ions and calcium ions; Synergistic extraction: The synergistic extraction organic phase is mixed with the extraction feed liquid and subjected to multi-stage countercurrent extraction to obtain a zinc-loaded organic phase; wherein, during the synergistic extraction process, the equilibrium pH of the aqueous phase is controlled at 1.9~2.6, so that zinc ions selectively enter the organic phase, while nickel, cobalt and manganese ions remain in the aqueous phase; Washing and back-extraction: The zinc-loaded organic phase is acid-washed and back-extracted to obtain a zinc-rich solution. The back-extracted organic phase is regenerated and recycled.

[0020] The method for targeted removal of zinc from complex polymetallic ion solutions by synergistic extraction provided in this invention has the following beneficial effects: (1) By using a synergistic extraction system, the limitations of a single extractant are overcome. In response to the technical bottleneck of poor selectivity of single P204 or P507, the synergistic extraction of the two has achieved a dual improvement in process stability and separation efficiency.

[0021] (2) High retention of manganese, nickel and cobalt, and high selectivity for zinc separation. This synergistic system exhibits high selectivity for zinc, significantly reducing manganese co-extraction loss under high concentration manganese solution conditions compared to traditional processes. At the same time, it effectively suppresses the entrainment of nickel and cobalt, greatly improving the recovery rate of valuable metals and reducing the load on subsequent washing and back-extraction processes.

[0022] (3) It has the advantages of being economical and environmentally friendly. The reagents used are all bulk industrial extractants, which are inexpensive and chemically stable. No toxic gases such as hydrogen sulfide are generated in the process, no difficult-to-filter residue is generated, the organic phase has good recycling performance, and it is suitable for large-scale industrial continuous production.

[0023] By controlling the pH value within the range of 1.9 to 2.6, efficient and selective extraction of zinc can be ensured. If the pH is below 1.9, the release of protons in the co-extraction system is limited, leading to incomplete zinc extraction; if the pH is above 2.6, it will cause co-extraction losses of manganese, nickel, and cobalt. After back-extraction, the organic phase is saponified with an alkaline solution such as sodium hydroxide, ammonia, or sodium carbonate to restore the extraction activity of the organic phase and ensure that it can be recycled for the next extraction process.

[0024] In some embodiments, in the co-extraction organic phase, the volume ratio of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (P507) to di(2-ethylhexyl) phosphate (P204) is 1:1 to 6:1, and the total volume concentration of the extractant is 5% to 20%.

[0025] Research has revealed that P507 is key to achieving selective zinc extraction in the synergistic extraction system. This specific ratio range fully utilizes the steric hindrance advantage of P507, ensuring zinc extraction while enhancing the separation coefficient between zinc and manganese-nickel-cobalt. Simultaneously, the addition of P204 effectively increases zinc extraction efficiency and lowers the operating pH, broadening its application prospects. Controlling the total extractant concentration between 5% and 20% ensures that the organic phase possesses good physical properties (including suitable viscosity and surface tension) under a certain zinc loading capacity, facilitating rapid separation of the two phases and reducing entrainment losses of the organic phase.

[0026] In some embodiments, the diluent is selected from at least one of sulfonated kerosene, 260# solvent oil, or aviation kerosene; the co-extracting organic phase is subjected to saponification treatment.

[0027] Diluents such as sulfonated kerosene, 260# solvent oil, and aviation kerosene possess advantages such as chemical stability, high flash point, and good solubility in the extractant. Before co-extraction, saponifying the organic phase of the co-extraction process can pre-neutralize protons in the extractant, reduce pH fluctuations in the aqueous phase during equilibrium extraction, and ensure process stability.

[0028] In some embodiments, the concentration of zinc ions in the complex polymetallic ion solution is 0.05 g / L to 0.5 g / L, the concentration of nickel ions is 0.3 g / L to 1.5 g / L, the concentration of cobalt ions is 0.3 g / L to 1.5 g / L, the concentration of manganese ions is 15 g / L to 40 g / L, the concentration of magnesium ions is 1 g / L to 3 g / L, and the concentration of calcium ions is 0.1 g / L to 1 g / L.

[0029] Specifically, the method of this invention is designed for complex systems with high manganese backgrounds, such as deep-sea polymetallic nodule leachates. It is then extended to selectively extract zinc from complex polymetallic ion solutions containing zinc, manganese, nickel, cobalt, calcium, and magnesium. Within this concentration range, traditional single extractants (P507 or P204) suffer from insufficient selectivity, leading to significant manganese co-extraction losses and low zinc extraction efficiency, resulting in a long extraction process.

[0030] In some embodiments, the liquid conditioning includes adjusting the pH value to 1.9-2.6 using at least one of sodium hydroxide solution, calcium oxide emulsion, magnesium oxide emulsion or ammonia water, the conditioning process being carried out at 20°C-50°C, and the stirring time being 20-60 minutes.

[0031] Specifically, sodium hydroxide, calcium oxide, magnesium oxide, or ammonia are all inexpensive, readily available industrial raw materials. Not only are they low-cost, but the introduced cations are easily handled in subsequent processes, preventing system contamination. Moderate heating (20℃~50℃) accelerates mass transfer and diffusion in the solution, shortening the time to reach pH equilibrium. Appropriate stirring (stirring for 20~60 minutes) ensures uniform and stable pH adjustment, preventing the precipitation of hydroxides from metal ions due to locally excessively high pH.

[0032] In some embodiments, the synergistic extraction includes: a multi-stage countercurrent extraction stage of 2 to 6 stages, an O / A ratio of 3:1 to 1:3, a single-stage extraction contact time of 1 to 10 minutes, and an extraction temperature of 20°C to 40°C.

[0033] Specifically, 2-6 stages of countercurrent extraction ensure deep zinc removal; compared to O / A ratios of 3:1-1:3, it provides flexible partitioning space, allowing adjustment of the organic phase load according to the feed zinc concentration, ensuring operational economy; the aforementioned contact time and temperature balance production efficiency and energy consumption. Extraction processes outside these parameter ranges will lead to reduced zinc extraction efficiency, reduced zinc extraction selectivity, and incomplete organic phase separation.

[0034] In some embodiments, during washing and back-extraction, acid washing uses a sulfuric acid solution with a concentration of 0.1 mol / L to 0.5 mol / L, the washing ratio O / A is 1:1 to 6:1, and the number of washing stages is 1 to 5.

[0035] The above-mentioned pickling process parameters ensure that, under the premise of a low zinc washing rate, the small amount of manganese, nickel, and cobalt ions entrained in the organic phase are preferentially replaced, reducing the loss rate of these valuable metals to below 0.3%. Pickling process parameters outside the above range will cause zinc to enter the pickling solution, leading to a decrease in the overall zinc extraction efficiency, or a decrease in the washing efficiency of manganese, nickel, and cobalt, making it difficult to effectively reduce the loss rate of manganese, nickel, and cobalt.

[0036] In some embodiments, during washing and back-extraction, a sulfuric acid solution with a concentration of 1.0 mol / L to 3.0 mol / L is used for back-extraction, the O / A ratio for back-extraction is 1:1 to 6:1, and the number of back-extraction stages is 2 to 6.

[0037] The above-mentioned back-extraction process parameters ensure efficient breakage of the bond between zinc and the organic phase, achieving a back-extraction rate of over 99%. Process parameters outside this range will result in reduced zinc back-extraction efficiency, or crystallization or organic phase degradation due to high-concentration acid solutions.

[0038] In summary, the method for targeted removal of zinc from complex polymetallic ion solutions through synergistic extraction provided in this embodiment of the invention is based on a synergistic solvent extraction system of P507 and P204. After synergistic extraction, the extraction rate of zinc reaches over 95%, the extraction rate of manganese is less than 1%, the extraction rate of nickel is less than 1%, and the extraction rate of cobalt is less than 1%. After acid washing, the loss rates of manganese, nickel, and cobalt are all reduced to below 0.3%. After back-extraction, the back-extraction rate of zinc reaches over 99%, resulting in a high-concentration zinc-rich solution and achieving the regeneration and recycling of the organic phase.

[0039] The composition of the complex polymetallic ion solutions used in the embodiments and comparative examples of this invention is shown in Table 1.

[0040] Table 1. Composition of complex polymetallic ion solutions used in the examples and comparative examples (g / L)

[0041] Example 1 This embodiment provides a method for the directional removal of zinc from complex polymetallic ion solutions through synergistic extraction. The specific steps are as follows: (1) Organic phase preparation: 2.5% P507 + 2.5% P204 + 95% sulfonated kerosene by volume was used as the organic phase for co-extraction; (2) Preparation of the extraction solution: Weigh 500 mL of solution No. 1 as the extraction solution and adjust the pH of the extraction solution to 2.6; (3) Co-extraction: The co-extraction organic phase and the extraction feed liquid were mixed and subjected to continuous countercurrent extraction for 6 stages at an extraction temperature of 40℃ to obtain the zinc-loaded organic phase and raffinate; wherein, the equilibrium pH of the aqueous phase was controlled at 2.6, the O / A ratio was 1:3, and the single-stage extraction time was 5 min; zinc ions selectively entered the organic phase, while nickel, cobalt and manganese ions remained in the aqueous phase. The composition and extraction rate of the raffinate are shown in Table 2. (4) Washing: The zinc-loaded organic phase was washed with 0.1 mol / L sulfuric acid solution. The washing ratio of O / A was 1:1, and the washing was performed in 5 consecutive countercurrent stages. The composition of the washing solution is shown in Table 3. (5) Back-extraction: The zinc-loaded organic phase was back-extracted using 2.0 mol / L sulfuric acid solution. The O / A ratio of the back-extraction ratio was 6:1, and the back-extraction was carried out in two consecutive countercurrent stages. The composition of the back-extraction solution is shown in Table 4.

[0042] Example 2 This embodiment provides a method for the directional removal of zinc from complex polymetallic ion solutions through synergistic extraction. The specific steps are as follows: (1) Organic phase preparation: 8% P507 + 4% P204 + 88% sulfonated kerosene (by volume) was used as the organic phase for co-extraction; (2) Preparation of the extraction solution: Weigh 500 mL of solution No. 2 as the extraction solution and adjust the pH of the extraction solution to 2.1; (3) Co-extraction: The co-extraction organic phase and the extraction feed liquid were mixed and subjected to continuous countercurrent extraction for 6 stages at an extraction temperature of 20℃ to obtain the zinc-loaded organic phase and raffinate; wherein, the equilibrium pH of the aqueous phase was controlled at 2.1, the O / A ratio was 1:2, and the single-stage extraction time was 3 min; zinc ions selectively entered the organic phase, while nickel, cobalt and manganese ions remained in the aqueous phase. The composition of the raffinate is shown in Table 2. (4) Washing: The zinc-loaded organic phase was washed with 0.1 mol / L sulfuric acid solution. The washing ratio of O / A was 2:1, and the washing was carried out in 4 consecutive countercurrent stages. The composition of the washing solution is shown in Table 3. (5) Back-extraction: The zinc-loaded organic phase was back-extracted using 2.0 mol / L sulfuric acid solution. The O / A ratio of the back-extraction ratio was 5:1, and the back-extraction was carried out in three consecutive countercurrent stages. The composition of the back-extraction solution is shown in Table 4.

[0043] Example 3 This embodiment provides a method for the directional removal of zinc from complex polymetallic ion solutions through synergistic extraction. The specific steps are as follows: (1) Organic phase preparation: 12% P507 + 2% P204 + 86% sulfonated kerosene by volume was used as the organic phase for co-extraction; (2) Preparation of the extraction solution: Weigh 500 mL of solution No. 3 as the extraction solution and adjust the pH of the extraction solution to 1.9; (3) Co-extraction: The co-extraction organic phase and the extraction liquid were mixed and subjected to continuous countercurrent extraction in 5 stages at an extraction temperature of 25℃ to obtain the zinc-loaded organic phase and raffinate; wherein, the pH value of the aqueous phase equilibrium was controlled at 1.9, the O / A ratio was 1:1, and the single-stage extraction time was 5 min; zinc ions selectively entered the organic phase, while nickel, cobalt and manganese ions remained in the aqueous phase. The composition of the raffinate is shown in Table 2. (4) Washing: The zinc-loaded organic phase was washed with 0.2 mol / L sulfuric acid solution. The washing ratio of O / A was 3:1, and the washing was carried out in three consecutive countercurrent stages. The composition of the washing solution is shown in Table 3. (5) Back-extraction: The zinc-loaded organic phase was back-extracted using 1.0 mol / L sulfuric acid solution. The back-extraction ratio O / A was 4:1, and the back-extraction was carried out in four consecutive countercurrent stages. The composition of the back-extraction solution is shown in Table 4.

[0044] Example 4 This embodiment provides a method for the directional removal of zinc from complex polymetallic ion solutions through synergistic extraction. The specific steps are as follows: (1) Organic phase preparation: 8% P507 + 2% P204 + 90% sulfonated kerosene by volume was used as the organic phase for co-extraction; (2) Preparation of the extraction solution: Weigh 500 mL of solution No. 1 as the extraction solution and adjust the pH of the extraction solution to 2.6; (3) Co-extraction: The co-extraction organic phase and the extraction feed liquid were mixed and subjected to continuous two-stage countercurrent extraction at an extraction temperature of 30℃ to obtain a zinc-loaded organic phase and raffinate; wherein, the equilibrium pH of the aqueous phase was controlled at 2.6, the O / A ratio was 1:1, and the single-stage extraction time was 7 min; zinc ions selectively entered the organic phase, while nickel, cobalt and manganese ions remained in the aqueous phase. The composition of the raffinate is shown in Table 2. (4) Washing: The zinc-loaded organic phase was washed with 0.3 mol / L sulfuric acid solution. The washing ratio of O / A was 4:1, and the washing was carried out in two consecutive countercurrent stages. The composition of the washing solution is shown in Table 3. (5) Back-extraction: The zinc-loaded organic phase was back-extracted using 1.0 mol / L sulfuric acid solution. The back-extraction ratio O / A was 4:1, and the back-extraction was carried out in 5 consecutive countercurrent stages. The composition of the back-extraction solution is shown in Table 4.

[0045] Example 5 This embodiment provides a method for the directional removal of zinc from complex polymetallic ion solutions through synergistic extraction. The specific steps are as follows: (1) Organic phase preparation: 10% P507 + 2% P204 + 88% sulfonated kerosene by volume was used as the organic phase for co-extraction; (2) Preparation of the extraction solution: Weigh 500 mL of solution No. 2 as the extraction solution and adjust the pH of the extraction solution to 2.1; (3) Co-extraction: The co-extraction organic phase and the extraction feed liquid were mixed and subjected to continuous three-stage countercurrent extraction at an extraction temperature of 35℃ to obtain a zinc-loaded organic phase and raffinate; wherein, the equilibrium pH of the aqueous phase was controlled at 2.1, the O / A ratio was 2:1, and the single-stage extraction time was 10 min; zinc ions selectively entered the organic phase, while nickel, cobalt and manganese ions remained in the aqueous phase. The composition of the raffinate is shown in Table 2. (4) Washing: The zinc-loaded organic phase was washed with 0.4 mol / L sulfuric acid solution. The washing ratio of O / A was 5:1, and a first-stage washing was performed. The composition of the washing solution is shown in Table 3. (5) Back-extraction: The zinc-loaded organic phase was back-extracted using 3.0 mol / L sulfuric acid solution. The O / A ratio of the back-extraction was 2:1, and the back-extraction was carried out in 6 consecutive countercurrent stages. The composition of the back-extraction solution is shown in Table 4.

[0046] Example 6 This embodiment provides a method for the directional removal of zinc from complex polymetallic ion solutions through synergistic extraction. The specific steps are as follows: (1) Organic phase preparation: 15% P507 + 5% P204 + 80% sulfonated kerosene by volume was used as the organic phase for co-extraction; (2) Preparation of the extraction solution: Weigh 500 mL of solution No. 3 as the extraction solution and adjust the pH of the extraction solution to 1.9; (3) Co-extraction: The co-extraction organic phase and the extraction feed liquid were mixed and subjected to continuous four-stage countercurrent extraction at an extraction temperature of 20℃ to obtain a zinc-loaded organic phase and raffinate; wherein, the equilibrium pH of the aqueous phase was controlled at 1.9, the O / A ratio was 3:1, and the single-stage extraction time was 1 min; zinc ions selectively entered the organic phase, while nickel, cobalt and manganese ions remained in the aqueous phase. The composition of the raffinate is shown in Table 2. (4) Washing: The zinc-loaded organic phase was washed with 0.5 mol / L sulfuric acid solution. The washing ratio of O / A was 6:1, and the washing was carried out in three consecutive countercurrent stages. The composition of the washing solution is shown in Table 3. (5) Back-extraction: The zinc-loaded organic phase was back-extracted using 3.0 mol / L sulfuric acid solution. The back-extraction ratio O / A was 1:1, and the back-extraction was carried out in four consecutive countercurrent stages. The composition of the back-extraction solution is shown in Table 4.

[0047] Comparative Example 1 The only difference between this comparative example and Example 3 is that in step (1) organic phase preparation, a volume fraction of 14% P2O4 + 86% sulfonated kerosene is used as the extraction organic phase; the composition of the raffinate is shown in Table 5.

[0048] Comparative Example 2 The only difference between this comparative example and Example 3 is that in step (1) organic phase preparation, 14% P507 + 86% sulfonated kerosene by volume fraction is used as the extraction organic phase; the composition of the raffinate is shown in Table 5.

[0049] Comparative Example 3 The only difference between this comparative example and Example 3 is that in step (3) co-extraction, a first-stage countercurrent extraction is performed; the composition of the raffinate is shown in Table 5.

[0050] Comparative Example 4 The only difference between this comparative example and Example 5 is that in step (3) co-extraction, the pH value of the aqueous phase equilibrium is controlled to be 1.7; the composition of the raffinate is shown in Table 5.

[0051] Comparative Example 5 The only difference between this comparative example and Example 5 is that in step (3) co-extraction, the pH value of the aqueous phase equilibrium is controlled at 2.8; the composition of the raffinate is shown in Table 5.

[0052] Table 2. Composition of raffinate obtained in the examples (g / L) and extraction rate (%)

[0053] Table 3. Composition of the washing solution obtained in the examples (g / L) and washing efficiency (%)

[0054] Table 4. Composition of the back-extraction solution obtained in the examples (g / L) and back-extraction rate (%)

[0055] Table 5. Composition of raffinate (g / L) and extraction rate (%) obtained from the comparative example

[0056] Results analysis: The results of Examples 1-6 verify that the synergistic extraction method for targeted zinc removal according to the embodiments of the present invention can effectively remove zinc from complex polymetallic ion solutions and minimize the loss of manganese, nickel, and cobalt. Table 2 shows that the zinc extraction rate reaches over 95%, and the co-extraction loss of manganese, nickel, and cobalt is less than 1%. Table 3 shows that the acid washing process can achieve further recovery of manganese, nickel, and cobalt with a relatively low zinc washing rate. In actual operation, the washing process parameters can be adjusted according to the actual concentration of different metals in the feed solution. Table 4 shows that the back-extraction process can achieve effective back-extraction of zinc, with an optimal back-extraction efficiency of over 99%, and can achieve the recycling and regeneration of the organic phase.

[0057] According to Table 5, the results of Comparative Examples 1-2 show that the co-extraction process can significantly improve the extraction efficiency of zinc and effectively reduce the co-extraction loss rate of manganese, nickel, and cobalt. The results of Comparative Example 3 show that when the countercurrent extraction stage is 1, it is difficult to achieve efficient zinc extraction under low equilibrium pH conditions. The results of Comparative Examples 4-5 show that the extraction equilibrium pH is crucial: efficient zinc extraction is difficult to achieve below pH 1.9; and above pH 2.6, it leads to high co-extraction loss rates of manganese, nickel, and cobalt. This indicates that the synergistic extraction process using P507 and P204 can achieve selective zinc extraction with a low extraction equilibrium pH, broadening the application prospects of the synergistic extraction system.

[0058] The core of this process lies in achieving efficient separation of key metals such as manganese, nickel, and cobalt, as well as zinc impurities, from complex polymetallic ion solutions, significantly improving the accuracy of solution separation and purification. This technology provides a practical and feasible technical path for the efficient extraction and purification of zinc from complex polymetallic ion solutions, and has significant practical significance and application prospects for promoting the development of related industries.

[0059] It will be readily understood by those skilled in the art that the above-described advantageous methods can be freely combined and superimposed without conflict. The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A method for the synergistic extraction and targeted removal of zinc from complex polymetallic ion solutions, characterized in that, Includes the following steps: Organic phase preparation: The extractant di(2-ethylhexyl) phosphate and the extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester were mixed, and a diluent was added to prepare a synergistic extraction organic phase; Feed solution control: The complex polymetallic ion solution is used as the extraction feed solution, and the pH value of the extraction feed solution is adjusted to 1.9~2.6; wherein, the complex polymetallic ion solution contains zinc ions, nickel ions, cobalt ions, manganese ions, magnesium ions and calcium ions; Synergistic extraction: The synergistic extraction organic phase is mixed with the extraction feed liquid and subjected to multi-stage countercurrent extraction to obtain a zinc-loaded organic phase; wherein, during the synergistic extraction process, the equilibrium pH of the aqueous phase is controlled at 1.9~2.6, so that zinc ions selectively enter the organic phase, while nickel, cobalt and manganese ions remain in the aqueous phase; Washing and back-extraction: The zinc-loaded organic phase is acid-washed and back-extracted to obtain a zinc-rich solution.

2. The method according to claim 1, characterized in that, In the synergistic extraction organic phase, the volume ratio of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester to di(2-ethylhexyl) phosphate ester is 1:1 to 6:1, and the total volume concentration of the extractant is 5% to 20%.

3. The method according to claim 1, characterized in that, The diluent is selected from at least one of sulfonated kerosene, 260# solvent oil, or aviation kerosene; the co-extracting organic phase is subjected to saponification treatment.

4. The method according to claim 1, characterized in that, In the complex polymetallic ion solution, the concentration of zinc ions is 0.05 g / L to 0.5 g / L, the concentration of nickel ions is 0.3 g / L to 1.5 g / L, the concentration of cobalt ions is 0.3 g / L to 1.5 g / L, the concentration of manganese ions is 15 g / L to 40 g / L, the concentration of magnesium ions is 1 g / L to 3 g / L, and the concentration of calcium ions is 0.1 g / L to 1 g / L.

5. The method according to claim 1, characterized in that, The liquid conditioning process includes adjusting the pH value to 1.9-2.6 using at least one of sodium hydroxide solution, calcium oxide emulsion, magnesium oxide emulsion, or ammonia water. The adjustment process is carried out at 20℃-50℃, and the stirring time is 20-60 minutes.

6. The method according to claim 1, characterized in that, The synergistic extraction includes: a multi-stage countercurrent extraction stage of 2 to 6 stages, an O / A ratio of 3:1 to 1:3, a single-stage extraction contact time of 1 to 10 minutes, and an extraction temperature of 20°C to 40°C.

7. The method according to claim 1, characterized in that, In the washing and back-extraction process, the acid washing uses a sulfuric acid solution with a concentration of 0.1 mol / L to 0.5 mol / L, the washing ratio O / A is 1:1 to 6:1, and the number of washing stages is 1 to 5.

8. The method according to claim 1, characterized in that, In the washing and back-extraction process, the back-extraction uses a sulfuric acid solution with a concentration of 1.0 mol / L to 3.0 mol / L, the back-extraction ratio O / A is 1:1 to 6:1, and the number of back-extraction stages is 2 to 6.

9. The method according to claim 1, characterized in that, Through the aforementioned synergistic extraction, the extraction rate of zinc reached over 95%, the extraction rate of manganese was less than 1%, the extraction rate of nickel was less than 1%, and the extraction rate of cobalt was less than 1%.

10. The method according to claim 1, characterized in that, The pickling process reduces the loss rates of manganese, nickel, and cobalt to below 0.3%.

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