A method for preparing battery precursors by deep-sea polymetallic leaching solution step-by-step impurity removal and directional enrichment

Abstract

The present application belongs to the technical field of nonferrous metallurgy, and relates to a method for preparing battery precursors by gradient impurity removal and directional enrichment of deep-sea polymetallic leaching solution. The method comprises the following steps: sequentially performing selective extraction of copper, water washing and back extraction on the deep-sea polymetallic leaching solution to obtain back extraction solution 1; performing neutralization precipitation to remove iron and aluminum from the raffinate 1 to obtain an iron and aluminum removal solution; performing sulfidation precipitation to remove zinc from the iron and aluminum removal solution to obtain a zinc removal solution; performing selective and cooperative extraction of nickel and cobalt, water washing and back extraction on the zinc removal solution to obtain back extraction solution 2; and performing fluoridation precipitation to remove calcium and magnesium from the raffinate 2 to finally obtain a manganese sulfate solution. The gradient separation system process of the present application is clear and efficient, the extraction system for the valuable metals has excellent selectivity, the impurities can be completely removed, the product has high purity, and the selection of reagents takes into account the cost and environmental protection.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metallurgical technology and relates to a method for preparing battery precursors by stepwise impurity removal and directional enrichment of deep-sea polymetallic leachate. Specifically, it relates to a method for stepwise impurity removal and directional enrichment of valuable metals from deep-sea polymetallic nucleic acid leachate, and for preparing battery-grade sulfates and battery material precursors. Background Technology

[0002] Deep-sea polymetallic nodules (hereinafter referred to as polymetallic nodules), also known as manganese nodules, are dark brown minerals widely distributed on the ocean floor at depths of 4,000 to 6,000 meters. Their main components are aluminosilicates, quartz, and iron and manganese oxide sediments, while also containing strategic metals such as nickel, cobalt, and copper. According to exploration statistics, 15% of the world's seabed is covered by polymetallic nodules, mainly distributed in the Pacific, Atlantic, and Indian Oceans. The total global ocean floor reserves are approximately 3 trillion tons, with the Pacific Ocean alone containing 1.7 trillion tons. Polymetallic nodules contain more than 70 elements, among which the most valuable for development—Mn, Ni, Co, and Cu—have average contents of 25-29%, 1.3-1.4%, 0.22-0.25%, and 1-1.3%, respectively. Their resource volume is tens to thousands of times that of terrestrial minerals. Furthermore, polymetallic nodules are increasing at a rate of 10 million tons per year, making them a mineral resource with immense commercial development potential and currently one of the most researched strategic resources. Meanwhile, manganese, nickel, cobalt, and copper are key strategic metals for industries such as new energy and energy storage, and are also four types of metals with extremely high foreign dependence in my country. In order to alleviate the supply and demand contradiction of key minerals in my country, support the development of emerging industries such as new energy and new materials, and ensure the security of my country's strategic resources, it is extremely important to shift the development focus of manganese, nickel, cobalt, and copper mineral resources from land resources to deep-sea polymetallic nodules with extremely abundant reserves.

[0003] Currently, polymetallic nodules are typically leached using sulfuric acid as the leaching agent, with the addition of reducing agents such as SO2 and Na2SO3. This reductive leaching process yields a leachate characterized by high manganese content and a complex system, containing not only manganese but also valuable metal ions such as nickel, cobalt, and copper, as well as impurity ions like iron, aluminum, calcium, magnesium, and zinc. The efficient and economical separation and enrichment of valuable metals from this complex system, characterized by high manganese content, numerous impurities, and high acidity, represents a technological bottleneck for the high-value utilization of deep-sea mineral resources.

[0004] Existing technologies include methods for preparing ternary precursors using reduction smelting-leaching-purification (e.g., CN201910040438.5), but these methods suffer from long process flows and high energy consumption. There are also methods for preparing copper sulfate, manganese carbonate, and ternary precursors using ammonia-ammonium carbonate reduction leaching-extraction separation (e.g., CN201811489309.6), but the ammonia process causes severe equipment corrosion, and ammonia nitrogen wastewater treatment is costly.

[0005] More importantly, for high-manganese polymetallic leaching solutions in sulfuric acid systems, especially for systematic hydrometallurgical processes that simultaneously achieve highly selective separation of nickel, cobalt, and manganese, as well as deep removal of difficult-to-remove impurities such as calcium, magnesium, and zinc, no successful reports have been found in existing technologies. Some studies have attempted to use P204 or P507 extraction to separate nickel, cobalt, and manganese, but due to insufficient separation coefficients between manganese and nickel / cobalt, the manganese content in the nickel-cobalt products often exceeds the standard, failing to meet the requirements for battery-grade raw materials.

[0006] Therefore, developing a method for efficient stepwise separation of valuable metals, deep removal of impurities, and direct preparation of battery-grade precursors from deep-sea polymetallic nucleic acid leachates has significant industrial value and urgent market demand. Summary of the Invention

[0007] This invention aims to provide a method for preparing battery precursors by stepwise impurity removal and directional enrichment of deep-sea polymetallic leachate, solving the problems of incomplete impurity removal, poor separation of nickel, cobalt and manganese, and insufficient product purity to meet the requirements of battery materials in the prior art, and providing a technical basis for realizing the high-value utilization of valuable metals in polymetallic nodules.

[0008] To achieve the above objectives, the present invention adopts the following technical solution.

[0009] A method for preparing battery precursors by stepwise impurity removal and directional enrichment of deep-sea multimetal leachate includes the following steps: Step 1: Selective extraction of copper, washing with water and back-extraction are performed sequentially on the deep-sea polymetallic leachate to obtain back-extraction solution 1, namely copper sulfate solution, and raffinate solution 1. Step 2: Neutralize and precipitate the raffinate 1 to remove iron and aluminum, and obtain an iron and aluminum-free solution; Step 3: Remove zinc by sulfidation precipitation of the iron and aluminum removal solution to obtain a zinc removal solution; Step 4: Selective synergistic extraction of nickel and cobalt, washing with water and back-extraction are performed on the zinc removal solution to obtain back-extraction solution 2, namely nickel cobalt manganese sulfate solution, and raffinate solution 2. Step 5: Fluoride precipitation is performed on the raffinate 2 to remove calcium and magnesium, finally yielding a manganese sulfate solution.

[0010] Furthermore, the main component of the deep-sea polymetallic leachate is manganese, and it also contains Fe, Ni, Co, Cu, Ca, Mg, Al, Zn and sulfuric acid; The composition range of the deep-sea polymetallic leachate is as follows: Mn 10-40 g / L, Fe 0.5-10 g / L, Ni 0.5-3 g / L, Co 0.2-2 g / L, Cu 0.2-3 g / L, Ca 0.5-2 g / L, Mg 0.5-3 g / L, Al 0.1-0.5 g / L, Zn 0.1-0.3 g / L, and sulfuric acid 20-100 g / L.

[0011] Further, in step 1, the copper extractant is a mixture of 5-nonylsalicylic acid oxime and 2-hydroxy-5-nonylacetophenone oxime, preferably Lix984N, M5540 or M5640, with a volume concentration of 5%-20%, an extraction pH of 1.5-2, and an extraction ratio (O / A) of 1:10-1:5.

[0012] Further, in step 1, the washing solution is a sulfuric acid solution of 1-5 g / L, the back-extraction agent is a sulfuric acid solution of 100-250 g / L, and the back-extraction ratio (O / A) is 2:1-10:1.

[0013] Furthermore, in step 2, the reagent used for neutralization precipitation is solid sodium hydroxide or potassium hydroxide, or a 1-5M sodium hydroxide or potassium hydroxide solution; the reaction temperature is 20-60℃, the reaction time is 0.5-1h, and the endpoint pH is controlled at 3.5-5.

[0014] Furthermore, in step 3, the reagent used for sulfide precipitation is sodium sulfide or sodium hydrosulfide solid, or a 1-5M solution thereof; the reaction temperature is 20-80℃, and the reaction time is 1-2h.

[0015] Preferably, if sodium sulfide is used, the amount added is 1.5-2g Na2S / g Zn; if sodium hydrosulfide is used, the amount added is 1-1.5g NaHS / g Zn.

[0016] Further, in step 4, the extractant is HBL110 extractant or DNNSA / 4PC synergistic extractant (composed of dinonylnaphthalenesulfonic acid (DNNSA) and decyl-4-pyridinecarboxylic acid ester (4PC); wherein, the volume concentration of HBL110 extractant is 20-50%; DNNSA and 4PC are prepared in a molar ratio of 1:2-1:4, and the volume concentration of DNNSA is 10-20%; the extraction ratio (O / A) is 4:1-1:5.

[0017] Further, in step 4, the washing solution is a sulfuric acid solution of 1-5 g / L, the back-extraction agent is a sulfuric acid solution of 100-250 g / L, and the back-extraction ratio (O / A) is 2:1-10:1.

[0018] Further, in step 5, the fluorination precipitant is sodium fluoride or potassium fluoride solid, or a 1-5M solution thereof; the reaction temperature is 40-95℃, and the reaction time is 0.5-2h; the molar amount of fluorine in the fluorination precipitant is 2.5-3 times the total molar amount of calcium and magnesium ions.

[0019] The separation principle of this technical solution is mainly based on the differences in the distribution behavior of metal ions between aqueous and organic or solid phases. By combining multiple methods such as extraction, precipitation, and precipitation displacement, selective separation and stepwise purification of multiple metals are achieved. The specific principle is as follows: (1) Selective extraction of copper (step 1): Utilizing the strong coordination ability and high selectivity of hydroxyoxime extractants (a mixture of 5-nonylsalicylic acid oxime and 2-hydroxy-5-nonylacetophenone oxime) for copper ions, Cu extraction is achieved under specific pH conditions. 2+ The copper is preferentially extracted into the organic phase; this process conforms to the "coordination-association" extraction mechanism, where copper forms a hydrophobic chelate with the oxime, thereby reacting with Mn. 2+ Ni 2+ Co 2+ After separation, copper is back-extracted with sulfuric acid solution to recover copper as pure copper sulfate solution, thus achieving preliminary enrichment and purification of copper.

[0020] (2) Neutralization and precipitation to remove iron and aluminum (step 2): The pH of the system is adjusted by adding alkaline solution (NaOH / KOH) to neutralize the easily hydrolyzed Fe. 3+ And Al 3+ Preferential formation of hydroxide precipitates (Fe(OH)3, Al(OH)3), utilizing the reaction of both with Mn 2+ Ni 2+ Co 2+ Significant differences in solubility under neutral to weakly acidic conditions enable solid-liquid separation and impurity removal.

[0021] (3) Zinc removal by sulfide precipitation (step 3): Introduce sulfides (Na2S / NaHS), utilizing the difference in solubility product (Ksp): ZnS has a very small Ksp (approximately 2×10). -25 While MnS, NiS, and CoS have larger solubility products under similar conditions, Zn... 2+ It preferentially precipitates out as ZnS to achieve deep zinc removal.

[0022] (4) Selective synergistic extraction of nickel and cobalt (step 4): Using a synergistic extraction system of DNNSA (dinonylnaphthalenesulfonic acid) and 4PC (4-pyridinecarboxylic acid ester), under weakly acidic conditions, the selective extraction of nickel and cobalt is achieved through a cation exchange and coordination synergistic mechanism. 2+ and Co 2+ Selective entry into the organic phase, while Mn 2+Impurity ions are retained in the aqueous phase; DNNSA provides acidic cation exchange function, and 4PC enhances the coordination selectivity and extraction kinetics for nickel and cobalt, achieving efficient separation of nickel, cobalt and manganese, and obtaining pure nickel-cobalt-manganese sulfate solution after back-extraction.

[0023] (5) Fluoride precipitation of calcium and magnesium (step 5): Add fluoride (NaF / KF), taking advantage of the extremely low solubility of CaF2 and MgF2 (Ksp are 3.9×10⁻⁶ respectively). -11 and 6.4×10 -9 ), to remove the remaining Ca 2+ Mg 2+ Mn is deeply removed in the form of fluoride precipitation, while... 2+ Because MnF2 has a high solubility (Ksp≈5.3×10⁻⁶), -3 The manganese sulfate solution is retained in the solution, and finally a high-purity manganese sulfate solution is obtained.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0025] 1. Clear and efficient process flow of the tiered separation system: For deep-sea leachates with complex composition, the system uses a precise tiered separation path of "extraction-precipitation-extraction-precipitation" to remove impurities such as copper, iron, aluminum, zinc, calcium, and magnesium in sequence, thereby achieving the enrichment and deep purification of the target metals nickel and cobalt, laying the foundation for the subsequent preparation of battery-grade products.

[0026] 2. Valuable metals are extracted using highly selective extraction systems: copper extraction uses specific oxime extractants, while nickel and cobalt extraction uses a DNNSA / 4PC synergistic system. Both exhibit high selectivity for the target metals. Combined with sulfuric acid washing and back-extraction, the main manganese and impurities are effectively separated, ensuring the efficient recovery of valuable metals such as nickel and cobalt.

[0027] 3. Thorough impurity removal and high product purity: Zinc is deeply removed through sulfidation precipitation, and difficult-to-remove calcium and magnesium ions are efficiently precipitated by fluorination, ultimately making the solution meet the stringent requirements of battery-grade sulfate for impurity ions.

[0028] 4. Reagent selection balances cost and environmental protection: The neutralization, sulfidation and fluorination steps use conventional inorganic reagents, which keeps costs under control; the extractant can be recycled, and the overall process is environmentally friendly and has good prospects for industrial application. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] Table 1. Main components of the deep-sea polymetallic leachate used in the experiment (g / L).

[0031] Example 1.

[0032] This embodiment provides a method for preparing battery precursors through stepwise impurity removal and directional enrichment of deep-sea multi-metal leachates. The specific steps are as follows: Weigh 1 L of sample 1 leachate and extract copper using Lix 984N. Perform five consecutive countercurrent extractions at a 5% extractant concentration, an extraction endpoint pH of 1.5, a ratio O / A of 1:10, and an extraction time of 7 min. After washing with 1 g / L sulfuric acid solution, back-extract with 150 g / L sulfuric acid solution at a ratio O / A of 2:1 and at room temperature for five consecutive countercurrent extractions to obtain 50 mL of back-extract 1. The composition of back-extract 1 is shown in Table 2. Raffinate 1 was prepared by reacting solid NaOH at 20°C for 1 hour, with the final pH value controlled at 3.5. After filtration, 0.45 g of Na2S was added to precipitate zinc, and the reaction was carried out at 20°C for 1 hour. After filtration, nickel and cobalt were extracted with HBL 110 extractant at a volume concentration of 40%, with a phase O / A ratio of 1:2 and 10 consecutive countercurrent extraction stages at 30°C. After washing with 1 g / L sulfuric acid solution, back-extraction was carried out with 150 g / L sulfuric acid solution at a phase O / A ratio of 5:1 and room temperature for 10 consecutive countercurrent extraction stages to obtain 100 mL of back-extraction solution 2, the composition of which is shown in Table 3. Add 18.2g of NaF solid to the raffinate 2, react at 40℃ for 2h, filter, and adjust the solution volume to 1 L. The solution composition is shown in Table 4.

[0033] Example 2.

[0034] This embodiment provides a method for preparing battery precursors through stepwise impurity removal and directional enrichment of deep-sea multi-metal leachates. The specific steps are as follows: Weigh 1 L of sample 2 leachate and extract copper using an M5540 extractant. Perform five consecutive countercurrent extractions at a 20% extractant concentration, an extraction endpoint pH of 2, a ratio O / A of 1:10, and an extraction time of 7 min. After washing with 3 g / L sulfuric acid solution, back-extract with 150 g / L sulfuric acid solution at a ratio O / A of 10:1 and at room temperature for five consecutive countercurrent extractions to obtain 10 mL of back-extract 1. The composition of back-extract 1 is shown in Table 2. Raffinate 1 was prepared by reacting KOH solid at 60℃ for 1 h, with the final pH value controlled at 5. After filtration, 0.2 g Na2S was added to precipitate zinc, and the reaction was carried out at 80℃ for 1 h. After filtration, nickel and cobalt were extracted with DNNSA-4PC extractant (molar ratio 1:4), with a DNNSA volume concentration of 10%. The extraction was carried out in 10 consecutive countercurrent stages at 30℃ with a phase O / A ratio of 1:5. After washing with 3 g / L sulfuric acid solution, back-extraction was carried out with 200 g / L sulfuric acid solution. The back-extraction was carried out in 10 consecutive countercurrent stages at room temperature with a phase O / A ratio of 10:1 to obtain 20 mL of back-extraction solution 2. The composition of back-extraction solution 2 is shown in Table 3. Add 5.76g of KF solid to the raffinate 2, react at 95℃ for 2h, filter, and adjust the solution volume to 1L. The solution composition is shown in Table 4.

[0035] Example 3.

[0036] This embodiment provides a method for preparing battery precursors through stepwise impurity removal and directional enrichment of deep-sea multi-metal leachates. The specific steps are as follows: Weigh 1 L of sample 3 leachate and extract copper using M5640. Perform 5 consecutive countercurrent extractions at a 10% extractant concentration, extraction endpoint pH 2, ratio O / A 1:5, and extraction time of 7 min. After washing with 5 g / L sulfuric acid solution, back-extract with 200 g / L sulfuric acid solution at a ratio O / A 2:1 and room temperature to obtain 100 mL of back-extract 1. Its composition is shown in Table 2. Raffinate 1 was prepared by reacting with 1 M NaOH solution at 40°C for 1 h, with the final pH value controlled at 4.5. After filtration, 4.6 mL of 1 M Na2S solution was added to precipitate zinc, and the reaction was carried out at 40°C for 1 h. After filtration, nickel and cobalt were extracted with DNNSA-4PC extractant (molar ratio 1:2), with a DNNSA volume concentration of 20%. The extraction was carried out continuously for 10 stages at 30°C with a ratio O / A of 1:2. After washing with 5 g / L sulfuric acid solution, back-extraction was carried out with 250 g / L sulfuric acid solution at a ratio O / A of 5:1 and at room temperature for 10 stages of countercurrent back-extraction to obtain 100 mL of back-extraction solution 2. Its composition is shown in Table 3. Add 280 mL of 1 M NaF solution to the raffinate 2, react at 70 °C for 2 h, filter, and adjust the solution volume to 1 L. The solution composition is shown in Table 4.

[0037] Example 4.

[0038] This embodiment provides a method for preparing battery precursors through stepwise impurity removal and directional enrichment of deep-sea multi-metal leachates. The specific steps are as follows: Weigh 1L of sample 1 leachate and extract copper using Lix984N. Perform five consecutive countercurrent extractions at an 8% extractant concentration, an extraction endpoint pH of 1.7, a ratio O / A of 1:10, and an extraction time of 7 min. After washing with 5 g / L sulfuric acid solution, back-extract with 150 g / L sulfuric acid solution at a ratio O / A of 2:1 and at room temperature to obtain 50 mL of back-extract 1. The composition of back-extract 1 is shown in Table 2. Raffinate 1 was prepared by reacting with 5M NaOH solution at 50℃ for 1 h, with the final pH value controlled at 3.8. After filtration, 1.2 mL of 5M Na2S solution was added to precipitate zinc, and the reaction was carried out at 60℃ for 1 h. After filtration, nickel and cobalt were extracted with DNNSA-4PC extractant (molar ratio 1:3), with a DNNSA volume concentration of 15%. The extraction was carried out at a ratio O / A of 1:2 and 30℃ for 10 consecutive countercurrent extraction stages. After washing with 5 g / L sulfuric acid solution, back-extraction was carried out with 200 g / L sulfuric acid solution at a ratio O / A of 5:1 and room temperature for 10 consecutive countercurrent back-extraction stages to obtain 100 mL of back-extraction solution 2, the composition of which is shown in Table 3. Add 104 mL of 5 M NaF solution to the raffinate 2, react at 60 °C for 2 h, filter, and adjust the solution volume to 1 L. The solution composition is shown in Table 4.

[0039] Example 5.

[0040] This embodiment provides a method for preparing battery precursors through stepwise impurity removal and directional enrichment of deep-sea multi-metal leachates. The specific steps are as follows: Weigh 1 L of sample 2 leachate and extract copper using an M5540 extractant. Perform five consecutive countercurrent extractions at a 10% extractant concentration, an extraction endpoint pH of 1.6, a ratio O / A of 1:10, and an extraction time of 7 min. After washing with 3 g / L sulfuric acid solution, perform back-extraction with 200 g / L sulfuric acid solution at a ratio O / A of 10:1 and at room temperature for five consecutive countercurrent extractions to obtain 10 mL of back-extraction solution 1. The composition of this solution is shown in Table 2. Raffinate 1 was prepared by reacting with 1M KOH solution at 30℃ for 1 h, with the final pH value controlled at 4.5. After filtration, 2.6 mL of 1M NaHS solution was added to precipitate zinc, and the reaction was carried out at 70℃ for 1 h. After filtration, nickel and cobalt were extracted with HBL110 extractant at a volume concentration of 30%, with a phase O / A ratio of 1:5 and 10 consecutive countercurrent extraction stages at 30℃. After washing with 3 g / L sulfuric acid solution, back-extraction was carried out with 250 g / L sulfuric acid solution, with a phase O / A ratio of 10:1 and 10 consecutive countercurrent back-extraction stages at room temperature, yielding 20 mL of back-extraction solution 2. The composition of back-extraction solution 2 is shown in Table 3. Add 83 mL of 1 M KF solution to the raffinate 2, react at 80 °C for 2 h, filter, and adjust the solution volume to 1 L. The solution composition is shown in Table 4.

[0041] Example 6.

[0042] This embodiment provides a method for preparing battery precursors through stepwise impurity removal and directional enrichment of deep-sea multi-metal leachates. The specific steps are as follows: Weigh 1 L of sample 3 leachate and extract copper using an M5640 extractor. Perform five consecutive countercurrent extractions at a 12% extractant concentration, an extraction endpoint pH of 1.9, a ratio O / A of 1:5, and an extraction time of 7 min. After washing with 1 g / L sulfuric acid solution, back-extract with 150 g / L sulfuric acid solution at a ratio O / A of 2:1 and at room temperature for five consecutive countercurrent extractions to obtain 100 mL of back-extract 1. The composition of this back-extract is shown in Table 2. Raffinate 1 was prepared by reacting with 5M KOH solution at 30℃ for 1 h, with the final pH value controlled at 4. After filtration, 0.9 mL of 5M NaHS solution was added to precipitate zinc, and the reaction was carried out at 50℃ for 1 h. After filtration, nickel and cobalt were extracted with HBL110 extractant at a volume concentration of 50%, and 10 consecutive countercurrent extractions were performed at 30℃ with a phase O / A ratio of 1:2. After washing with 1 g / L sulfuric acid solution, back-extraction was performed with 100 g / L sulfuric acid solution at a phase O / A ratio of 5:1 and at room temperature for 10 consecutive countercurrent extractions to obtain 100 mL of back-extraction solution 2, the composition of which is shown in Table 3. Add 67 mL of 5 M KF solution to the raffinate 2, react at 90 °C for 2 h, filter, and adjust the solution volume to 1 L. The solution composition is shown in Table 4.

[0043] Table 2 Components of Back-extraction Solution 1 in Examples (Note: The concentration of metal ions other than Cu / Fe / Al is in mg / L.)

[0044] Table 3 Components of the back-extraction solution 2 in the examples (Note: The concentration of metal ions other than Ni / Co / Mn is in mg / L.)

[0045] Table 4. Composition of the final manganese sulfate solution in the examples (Note: The concentration of metal ions other than Mn is in mg / L.)

[0046] Comparative Example 1.

[0047] The only difference between this comparative example and Example 3 is that in step 4, the DNNSA-4PC synergistic extractant (DNNSA to 4PC molar ratio 1:2, DNNSA volume concentration 20%) is replaced with a single P507 extractant of equal volume concentration (20 vol%). All other steps and parameters are completely consistent with Example 3. The specific steps are as follows: Weigh 1 L of sample 3 leachate (composition as in Table 1, sample 3), extract copper using M5640, and perform 5 consecutive countercurrent extractions at a 10% extractant concentration, extraction endpoint pH 2, ratio O / A 1:5, and extraction time of 7 min. After washing with 5 g / L sulfuric acid solution, back-extract with 200 g / L sulfuric acid solution at a ratio O / A 2:1 and room temperature to obtain 100 mL of back-extract solution 1. Raffinate 1 was reacted with 1M NaOH solution at 40℃ for 1 h, with the final pH controlled at 4.5. After filtration, 4.6 mL of 1M Na₂S solution was added to precipitate zinc, and the reaction was carried out at 40℃ for 1 h. After filtration, nickel and cobalt were extracted with P507 extractant (20% v / v, sulfonated kerosene as diluent) at 30℃ using 10 consecutive countercurrent extraction stages. After washing with 5 g / L sulfuric acid solution, back-extraction was carried out with 250 g / L sulfuric acid solution at 5:1 O / A ratio and room temperature using 10 consecutive countercurrent back-extraction stages, yielding 100 mL of back-extraction solution 2. Raffinate 2 was then added to 280 mL of 1M NaF solution, reacted at 70℃ for 2 h, filtered, and the solution volume was adjusted to 1 L.

[0048] The components of the back-extraction solution 2 and the final manganese sulfate solution are shown in Table 5.

[0049] Comparative Example 2.

[0050] The only difference between this comparative example and Example 3 is the order of steps: nickel-cobalt extraction is performed first (step 4), followed by zinc sulfide precipitation removal (step 3). All other steps and parameters are identical to those in Example 3. The specific steps are as follows: Weigh 1 L of sample 3 leachate (composition as in Table 1, sample 3), extract copper using M5640, and perform 5 consecutive countercurrent extractions at a 10% extractant concentration, extraction endpoint pH 2, ratio O / A 1:5, and extraction time of 7 min. After washing with 5 g / L sulfuric acid solution, back-extract with 200 g / L sulfuric acid solution at a ratio O / A 2:1 and room temperature to obtain 100 mL of back-extract solution 1. Raffinate 1 was reacted with 1M NaOH solution at 40℃ for 1 h, with the final pH controlled at 4.5. After filtration to remove iron and aluminum precipitates, without zinc precipitation, nickel and cobalt were directly extracted using DNNSA-4PC extractant (molar ratio 1:2, DNNSA volume concentration 20%) at 30℃ for 10 consecutive countercurrent extraction stages. After washing with 5 g / L sulfuric acid solution, back-extraction was performed with 250 g / L sulfuric acid solution at 5:1 O / A ratio and room temperature for 10 consecutive countercurrent extraction stages, yielding 100 mL of back-extraction solution 2. 4.6 mL of 1M Na2S solution was added to back-extraction solution 2 to precipitate zinc, and the reaction was carried out at 40℃ for 1 h, followed by filtration. Due to the extremely high nickel and cobalt concentration in back-extraction solution 2, a severe co-precipitation effect of the same ions occurred during the zinc sulfide precipitation process, resulting in a significant loss of nickel and cobalt along with ZnS co-precipitation. Finally, add 280 mL of 1 M NaF solution, react at 70 °C for 2 h, filter, and adjust the solution volume to 1 L.

[0051] The components of the back-extraction solution 2 and the final manganese sulfate solution are shown in Table 5.

[0052] Comparative Example 3.

[0053] The only difference between this comparative example and Example 3 is that in step 5, the amount of fluorinated precipitant NaF is reduced, lowering the F / (Ca+Mg) molar ratio to 1.5, i.e., 168 mL of 1M NaF solution is added (replacing the 280 mL of 1M NaF solution in Example 3); the remaining steps and parameters are completely consistent with Example 3. The specific steps are as follows: Weigh 1 L of sample 3 leachate (composition as in Table 1, sample 3), extract copper using M5640, and perform 5 consecutive countercurrent extractions at a 10% extractant concentration, extraction endpoint pH 2, ratio O / A 1:5, and extraction time of 7 min. After washing with 5 g / L sulfuric acid solution, back-extract with 200 g / L sulfuric acid solution at a ratio O / A 2:1 and room temperature to obtain 100 mL of back-extract solution 1. Raffinate 1 was reacted with 1M NaOH solution at 40°C for 1 hour, with the final pH controlled at 4.5. After filtration, 4.6 mL of 1M Na2S solution was added to precipitate zinc, and the reaction was carried out at 40°C for 1 hour. After filtration, nickel and cobalt were extracted with DNNSA-4PC extractant (molar ratio 1:2, DNNSA volume concentration 20%) at 30°C for 10 consecutive countercurrent extraction stages. After washing with 5 g / L sulfuric acid solution, back-extraction was carried out with 250 g / L sulfuric acid solution at 5:1 O / A ratio and room temperature for 10 consecutive countercurrent extraction stages, yielding 100 mL of back-extraction solution 2 (composition as in Example 3, Table 3, Example 3). Raffinate 2 was added to 168 mL of 1M NaF solution (F / (Ca+Mg) molar ratio = 1.5), reacted at 70°C for 2 hours, filtered, and the solution volume was adjusted to 1 L.

[0054] The final composition of the manganese sulfate solution is shown in Table 5.

[0055] Comparative Example 4.

[0056] The only difference between this comparative example and Example 3 is that in step 5, the amount of fluorinated precipitant NaF is increased, raising the F / (Ca+Mg) molar ratio to 4.0, i.e., 448 mL of 1M NaF solution is added (replacing the 280 mL of 1M NaF solution in Example 3); the remaining steps and parameters are completely consistent with Example 3. The specific steps are as follows: Weigh 1 L of sample 3 leachate (composition as in Table 1, sample 3), extract copper using M5640, and perform 5 consecutive countercurrent extractions at a 10% extractant concentration, extraction endpoint pH 2, ratio O / A 1:5, and extraction time of 7 min. After washing with 5 g / L sulfuric acid solution, back-extract with 200 g / L sulfuric acid solution at a ratio O / A 2:1 and room temperature to obtain 100 mL of back-extract solution 1. Raffinate 1 was reacted with 1M NaOH solution at 40°C for 1 hour, with the final pH controlled at 4.5. After filtration, 4.6 mL of 1M Na₂S solution was added to precipitate zinc, and the reaction was carried out at 40°C for 1 hour. After filtration, nickel and cobalt were extracted with DNNSA-4PC extractant (molar ratio 1:2, DNNSA volume concentration 20%) at 30°C for 10 consecutive countercurrent extraction stages. After washing with 5 g / L sulfuric acid solution, back-extraction was carried out with 250 g / L sulfuric acid solution at a relative O / A ratio of 5:1 at room temperature for 10 consecutive countercurrent extraction stages, yielding 100 mL of back-extraction solution 2 (composition as in Example 3, Table 3, Example 3). Raffinate 2 was added to 448 mL of 1M NaF solution (F / (Ca+Mg) molar ratio = 4.0), reacted at 70°C for 2 hours, filtered, and the solution volume was adjusted to 1 L.

[0057] The final composition of the manganese sulfate solution is shown in Table 5.

[0058] Table 5 Comparison of key indicators between Example 3 and the comparative example (Note: The Ni / Co recovery rate of Comparative Examples 1-2 is calculated according to the process of steps 1-4; the Mn recovery rate of Comparative Examples 3-4 is calculated according to the entire process of steps 1-5.)

[0059] Table 5 summarizes the key indicators of Example 3 and each comparative example. A thorough comparative analysis of the data from Example 3 and each comparative example leads to the following conclusions: 1. The irreplaceability of the DNNSA-4PC synergistic extraction system: Comparing Example 3 and Comparative Example 1, it can be seen that when the DNNSA-4PC synergistic extractant is replaced with a single P507 extractant, the recovery rate of nickel decreases from 97.1% to 84.5%, the recovery rate of cobalt decreases from 92.7% to 79.3%, and the co-extracted amount of manganese in the back-extraction solution 2 increases significantly (from 7.67 g / L to 14.52 g / L); traditional single acidic phosphorus extractants (such as P507) are less effective in treating high-manganese background solutions due to the presence of Mn. 2+ with Ni 2+ Co 2+All three are divalent transition metal ions with similar ionic radii, making it impossible for a single coordination mechanism to effectively distinguish them, leading to extensive co-extraction of manganese. The DNNSA-4PC synergistic extraction system employed in this invention utilizes the synergistic effect of sulfonic acid cation exchange groups and pyridine strong coordinating groups—DNNSA provides the driving force for cation exchange, and 4PC provides axial coordination selectivity—the two jointly coordinate octahedral Mn. 2+ This creates steric hindrance and thermodynamic repulsion, thereby effectively suppressing the co-extraction of manganese while ensuring a high extraction rate of nickel and cobalt.

[0060] 2. The rationality of the step-by-step impurity removal sequence: Comparing Example 3 and Comparative Example 2, it can be seen that when the order of first extracting nickel and cobalt and then removing zinc is adopted, the zinc content in the back-extraction solution 2 is as high as 18.5 mg / L (compared to only 0.2 mg / L in Example 3), indicating that zinc is co-extracted into the organic phase in large quantities during the nickel and cobalt extraction stage—this is because Zn 2+ with Ni 2+ Co 2+ The partition coefficients in the DNNSA-4PC system are quite similar; without pre-stripping, they will directly contaminate the nickel-cobalt extraction phase. More seriously, during zinc sulfide precipitation in the enriched, high-concentration back-extraction solution, the presence of Ni in the solution... 2+ Co 2+ Extremely high concentrations inevitably trigger co-precipitation of common ions, leading to the loss of nickel and cobalt along with ZnS, reducing the overall nickel recovery rate to 84.2% and the cobalt recovery rate to 79.5%. The step-by-step sequence of "first sulfidation and zinc precipitation, then co-extraction of nickel and cobalt" specified in this application not only avoids zinc co-extraction contamination but also fundamentally prevents the loss of nickel and cobalt caused by subsequent zinc removal, which is a prerequisite for ensuring a high direct recovery rate of all multi-metal components.

[0061] 3. Threshold control of fluorination precipitant dosage: Example 3, along with Comparative Examples 3 and 4, defined a narrow operating window for fluorination precipitation to remove calcium and magnesium. When the F / (Ca+Mg) molar ratio decreased to 1.5 (Comparative Example 3), the amount of fluorinating agent was insufficient, and the precipitation reactions of CaF2 and MgF2 were incomplete. Ultimately, the residual Ca in the manganese sulfate solution reached as high as 126 mg / L and the residual Mg reached as high as 168 mg / L (compared to only 1.2 mg / L and 1.7 mg / L in Example 3), far from meeting the stringent requirements for calcium and magnesium impurities in battery-grade manganese sulfate (typically requiring Ca+Mg < 10 mg / L). When the F / (Ca+Mg) molar ratio increased to 4.0 (Comparative Example 4), although Ca and Mg were deeply removed to 0.6 mg / L and 0.8 mg / L respectively, the presence of free F in the system... - The concentration was too high, exceeding the solubility product of MnF2 (Ksp≈5×10). -3This resulted in a significant loss of the main metal manganese through co-precipitation in the form of MnF2, causing the manganese recovery rate to plummet from 95.43% in Example 3 to 81.26%. The molar ratio range of F / (Ca+Mg) = 2.5-3.0 defined in this invention precisely balances the thermodynamic driving force of calcium fluoride / magnesium fluoride precipitation with the critical point of the manganese fluoride solubility product.

[0062] Based on the results of Examples 1-6 and Comparative Examples 1-4, the stepwise impurity removal and directional enrichment process proposed in this invention has significant inventiveness in the following three aspects: (1) The DNNSA-4PC synergistic extraction system, through the synergistic superposition of cation exchange and coordination chemistry, achieves for the first time highly selective separation of nickel and cobalt in a sulfuric acid system under a manganese background; (2) The process sequence design of "first sulfidation precipitation of zinc, then synergistic extraction of nickel and cobalt" fundamentally solves the problem of loss of valuable metals caused by co-extraction of zinc and nickel and cobalt and subsequent zinc removal; (3) The precise threshold control of the F / (Ca+Mg) molar ratio of 2.5-3.0 finds the optimal balance between deep removal of calcium and magnesium and high recovery rate of manganese. The organic combination of the above technical features enables this invention to efficiently and economically obtain analytical grade copper sulfate, battery grade nickel cobalt manganese sulfate, and high-purity manganese sulfate solution from the complex system of deep-sea polymetallic nodule sulfuric acid leaching solution, providing a practical and feasible technical path for the commercial development of deep-sea mineral resources.

[0063] The results of Examples 1-6 verify that the step-by-step impurity removal and directional enrichment process of this invention can effectively purify analytical grade copper sulfate and battery-grade nickel-cobalt-manganese sulfate solutions from deep-sea polymetallic nucleic acid leaching solutions. The copper sulfate solution has a copper ion concentration enriched to 20-30 g / L, with extremely low impurity content, meeting the raw material requirements for copper electrodeposition. The nickel-cobalt-manganese sulfate solution has a nickel ion concentration of 15-30 g / L, and cobalt and manganese ion concentrations are both in the range of 10-20 g / L, with low impurity content, and can be used to prepare nickel-cobalt-manganese oxide precursors after simple component adjustment. The manganese sulfate solution has low impurity content, with a manganese ion concentration of 10-37 g / L, meeting the production requirements for electrolytic manganese dioxide (EMD). Throughout the process, the copper recovery rate is over 99%, the nickel recovery rate is over 97.5%, the cobalt recovery rate is over 92%, and the manganese recovery rate is over 95%.

[0064] The method proposed in this invention constructs a tiered separation and purification system for sulfuric acid leaching solutions of deep-sea polymetallic nodules. This system achieves tiered and targeted enrichment and separation of four key metals: manganese, nickel, cobalt, and copper, effectively removing impurities such as iron, aluminum, calcium, magnesium, and zinc, significantly improving the accuracy of metal recovery and the added value of the products. The resulting analytical-grade copper sulfate, battery-grade nickel-cobalt-manganese sulfate, and high-purity manganese sulfate solutions can be directly used as important precursors for subsequent copper electrowinning processes, the synthesis of nickel-cobalt-manganese oxide cathode materials, and manganese electrowinning production, forming a complete resource utilization chain. This technology not only solves the key challenges of complex composition, numerous impurities, and difficult separation in deep-sea polymetallic nodule leaching solutions, but also provides a practical and feasible technical path for the efficient extraction and high-value utilization of polymetals in deep-sea mineral resources. It has significant practical significance and application prospects for promoting the commercial and large-scale development of deep-sea mineral resources.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any minor modifications, equivalent substitutions, and improvements made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing battery precursors by stepwise impurity removal and directional enrichment of deep-sea polymetallic leachate, characterized in that, The steps include the following: Step 1: Selective extraction of copper, washing with water and back-extraction are performed sequentially on the deep-sea polymetallic leachate to obtain back-extraction solution 1, namely copper sulfate solution, and raffinate solution 1. Step 2: Neutralize and precipitate the raffinate 1 to remove iron and aluminum, and obtain an iron and aluminum-free solution; Step 3: Remove zinc by sulfidation precipitation of the iron and aluminum removal solution to obtain a zinc removal solution; Step 4: Selective synergistic extraction of nickel and cobalt, washing with water and back-extraction are performed on the zinc removal solution to obtain back-extraction solution 2, namely nickel cobalt manganese sulfate solution, and raffinate solution 2. Step 5: Fluoride precipitation is performed on the raffinate 2 to remove calcium and magnesium, finally yielding a manganese sulfate solution.

2. The method for preparing battery precursors by stepwise impurity removal and directional enrichment of deep-sea polymetallic leachate according to claim 1, characterized in that, The main component of the deep-sea polymetallic leachate is manganese, and it also contains Fe, Ni, Co, Cu, Ca, Mg, Al, Zn and sulfuric acid. The composition range of the deep-sea polymetallic leachate is as follows: Mn 10-40 g / L, Fe 0.5-10 g / L, Ni 0.5-3 g / L, Co 0.2-2 g / L, Cu 0.2-3 g / L, Ca 0.5-2 g / L, Mg 0.5-3 g / L, Al 0.1-0.5 g / L, Zn 0.1-0.3 g / L, and sulfuric acid 20-100 g / L.

3. The method for preparing battery precursors by stepwise impurity removal and directional enrichment of deep-sea polymetallic leachate according to claim 1, characterized in that, In step 1, the copper extractant is a mixture of 5-nonylsalicylic acid oxime and 2-hydroxy-5-nonylacetophenone oxime, with a volume concentration of 5%-20%, an extraction pH of 1.5-2, and an extraction ratio (O / A) of 1:10-1:

5.

4. The method for preparing battery precursors by stepwise impurity removal and directional enrichment of deep-sea polymetallic leachate according to claim 1, characterized in that, In step 1, the washing solution is a sulfuric acid solution of 1-5 g / L, the back-extraction agent is a sulfuric acid solution of 100-250 g / L, and the back-extraction ratio (O / A) is 2:1-10:

1.

5. The method for preparing battery precursors by stepwise impurity removal and directional enrichment of deep-sea polymetallic leachate according to claim 1, characterized in that, In step 2, the reagent used for neutralization precipitation is solid sodium hydroxide or potassium hydroxide, or a 1-5M sodium hydroxide or potassium hydroxide solution; the reaction temperature is 20-60℃, the reaction time is 0.5-1h, and the endpoint pH is controlled to be 3.5-5.

6. The method for preparing battery precursors by stepwise impurity removal and directional enrichment of deep-sea polymetallic leachate according to claim 1, characterized in that, In step 3, the reagent used for sulfide precipitation is sodium sulfide or sodium hydrosulfide solid, or a 1-5M solution thereof; the reaction temperature is 20-80℃, and the reaction time is 1-2h.

7. The method for preparing battery precursors by stepwise impurity removal and directional enrichment of deep-sea polymetallic leachate according to claim 6, characterized in that, If sodium sulfide is used, the amount added is 1.5-2g Na2S / g Zn; if sodium hydrosulfide is used, the amount added is 1-1.5g NaHS / g Zn.

8. The method for preparing battery precursors by stepwise impurity removal and directional enrichment of deep-sea polymetallic leachate according to claim 1, characterized in that, In step 4, the extractant is HBL110 extractant or DNNSA / 4PC synergistic extractant; wherein, the volume concentration of HBL110 extractant is 20-50%; DNNSA and 4PC are prepared in a molar ratio of 1:2-1:4, and the volume concentration of DNNSA is 10-20%; the extraction ratio (O / A) is 4:1-1:

5.

9. The method for preparing battery precursors by stepwise impurity removal and directional enrichment of deep-sea polymetallic leachate according to claim 1, characterized in that, In step 4, the washing solution is a sulfuric acid solution of 1-5 g / L, the back-extraction agent is a sulfuric acid solution of 100-250 g / L, and the back-extraction ratio (O / A) is 2:1-10:

1.

10. The method for preparing battery precursors by stepwise impurity removal and directional enrichment of deep-sea polymetallic leachate according to claim 1, characterized in that, In step 5, the fluorination precipitant is sodium fluoride or potassium fluoride solid, or a 1-5M solution thereof; the reaction temperature is 40-95℃, and the reaction time is 0.5-2h; the molar amount of fluorine in the fluorination precipitant is 2.5-3 times the total molar amount of calcium and magnesium ions.

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