Method for nickel-cobalt synergistic extraction and separation thereof from scandium and manganese

Abstract

This invention discloses a method for synergistic extraction of nickel and cobalt and its separation from scandium and manganese, belonging to the field of nickel-cobalt extraction technology. The method includes: leaching a nickel-cobalt-containing material with sulfuric acid solution, followed by solid-liquid separation to obtain a first leachate; introducing a first oxidant into the first leachate for first oxidation, oxidizing ferrous iron to ferric iron, obtaining a first oxidized leachate; subjecting the first oxidized leachate to alum precipitation to remove iron, followed by solid-liquid separation to obtain scandium-iron-vanadium slag and a second leachate; adding a second oxidant into the second leachate for second oxidation, oxidizing ferrous manganese to tetravalent manganese, followed by solid-liquid separation to obtain manganese oxide precipitate and a third leachate after manganese removal; and using a synergistic extractant to extract nickel and cobalt from the third leachate, with the nickel and cobalt being extracted into the organic phase. This invention enables the separation of nickel and cobalt from scandium and manganese, allowing extraction under lower pH conditions and improving nickel-cobalt extraction efficiency.

Description

Technical Field

[0001] This invention relates to the field of nickel-cobalt extraction technology, and in particular to a method for nickel-cobalt synergistic extraction and its separation from scandium-manganese. Background Technology

[0002] Lateritic nickel ore has become a major nickel-cobalt resource, with associated scandium resources. The hydrometallurgical process for lateritic nickel ore consists of acid leaching, impurity removal, and nickel-cobalt precipitation. Nickel-cobalt hydroxide precipitation is a common intermediate product obtained from the hydrometallurgical process of lateritic nickel ore. The purpose of the nickel-cobalt hydroxide refining process is to remove impurities from the system to obtain nickel-cobalt metal or its compounds.

[0003] Besides nickel and cobalt, nickel-cobalt hydroxide also contains iron and manganese. During the acid leaching reaction, nickel-cobalt hydroxide enters the leaching solution along with the nickel and cobalt, requiring a refining and separation process to remove iron and obtain a pure nickel-cobalt product. Iron ions are the main impurities in the separation and utilization of valuable metals, and the iron alum process is a commonly used method for iron removal. The iron ions in the nickel-cobalt hydroxide leaching solution are both divalent and trivalent. The inventors have noted that the conventional iron alum process suffers from the problem that the oxidation pH of divalent iron is much higher than the pH of alum precipitation. Oxidants used within the suitable pH range for alum precipitation have disadvantages such as slow oxidation rates and high costs. Manganese is one of the impurities leached along with nickel and cobalt and treated in subsequent separation processes. Manganese interferes with the extraction of nickel and cobalt, affecting product purity. Moreover, a significant amount of nickel-cobalt hydroxide produced from laterite nickel ore contains scandium, which is a harmful impurity in nickel-cobalt smelting and is also a rare earth resource. Because scandium has a low concentration in the system and a relatively high content of impurities, existing technologies for removing and enriching scandium by precipitation have problems such as low precipitation rate of low-concentration scandium and difficulty in settling the precipitate. Existing technologies for purifying and separating scandium by extraction have problems such as low extraction and separation efficiency of scandium from impurities such as iron and aluminum and difficulty in back-extraction.

[0004] Patent CN103468948B discloses a method for treating nickel-cobalt hydroxide containing scandium. During further iron and aluminum removal, the pH value is adjusted to 3.0 or higher to co-precipitate scandium with iron and aluminum, which then precipitates as hydroxide, achieving the removal and recovery of scandium from the nickel-cobalt solution. However, in practice, the inventors further discovered a problem with this process: during hydroxide co-precipitation, the special properties of aluminum hydroxide and scandium hydroxide dissolving in strong alkalis make it difficult to determine the reaction endpoint, and the endpoint pH is difficult to control precisely. Too low a pH value easily leads to low scandium recovery, while too high a pH value easily results in colloidal precipitation, affecting filtration performance. Furthermore, the reaction is carried out at a higher pH value, increasing the loss of nickel, cobalt, and manganese in the slag. Patent CN115094229B discloses a method for recovering scandium from nickel-cobalt hydroxide produced from laterite nickel ore. This method involves reducing and leaching a nickel-cobalt hydroxide slurry, followed by iron removal from the leaching solution using a goethite method. This results in a goethite-type precipitate containing or adsorbing scandium, and a nickel-cobalt-containing solution, simultaneously enriching the scandium through co-precipitation. However, further research by the inventors revealed that the reducing leaching causes manganese to become divalent, resulting in a high manganese content in the nickel-cobalt solution, which affects nickel-cobalt extraction and increases the difficulty of subsequent extraction. Therefore, through further improvements, a method is proposed that can separate nickel-cobalt from scandium and manganese, thereby improving the efficiency of nickel-cobalt extraction. Summary of the Invention

[0005] According to one embodiment of the present invention, the objective is to provide a method for nickel-cobalt co-extraction and its separation from scandium-manganese. The method employs stepwise oxidation coupled with vanadium precipitation for iron removal and scandium co-precipitation and manganese separation, and uses a co-extraction system to extract nickel-cobalt, thereby achieving the separation of nickel-cobalt from scandium-manganese. Nickel-cobalt can be extracted under lower pH conditions, and nickel-cobalt is directly extracted into the organic phase, thus improving the nickel-cobalt extraction efficiency.

[0006] The above objective can be achieved through the following technical solutions:

[0007] According to one aspect of the present invention, a method for nickel-cobalt co-extraction and its separation from scandium-manganese is provided, comprising:

[0008] Step S1: Add sulfuric acid solution to the nickel-cobalt-containing material for leaching, and separate the solid and liquid to obtain the first leachate;

[0009] Step S2: A first oxidant is introduced into the first leachate to perform a first oxidation, which oxidizes ferrous iron to ferric iron, and a leachate with the first oxidation is obtained.

[0010] Step S3: The first oxidized leachate is subjected to alum precipitation and iron removal using the iron-vanadium ore method, followed by solid-liquid separation to obtain scandium-containing iron-vanadium slag and a second leachate after iron and scandium removal.

[0011] Step S4: Add a second oxidant to the second leachate to perform a second oxidation, oxidizing divalent manganese to tetravalent manganese, and then separate the solid and liquid to obtain manganese oxide precipitate residue and a third leachate after manganese removal.

[0012] Step S5: The third leachate is subjected to nickel-cobalt extraction using a synergistic extractant to obtain a nickel-cobalt supported organic phase; wherein the synergistic extractant is prepared using an acidic organophosphorus extractant and a hydroxyoxime extractant.

[0013] Preferably, step S2 further includes: adjusting the pH of the first leachate to 1.0–4.5 and the temperature to 20–45°C. More preferably, the pH of the first leachate is adjusted to 2.0–4.0 and the temperature to 30–40°C.

[0014] Preferably, step S4 further includes: adjusting the pH of the second leachate to 3.0–6.5 and the temperature to 45–95°C. More preferably, the pH of the second leachate is adjusted to 4.0–6.0 and the temperature to 55–85°C.

[0015] Preferably, the first oxidant is oxygen or air.

[0016] Preferably, the second oxidant is SO2 and oxygen / air.

[0017] More preferably, the volume fraction ratio of SO2 to oxygen is (3-20):100.

[0018] Preferably, step S2 further includes adding a Cu(II)-containing reagent as a catalyst for the first oxidation reaction. More preferably, the concentration of Cu(II) ions in the Cu(II)-containing reagent is 0.005–0.05 mol / L.

[0019] Preferably, step S4 further includes adding a Fe(III)-containing reagent as a catalyst for the second oxidation reaction. More preferably, the concentration of Fe(III) ions in the Fe(III)-containing reagent is 0.001–0.1 mol / L.

[0020] Preferably, the molar ratio of the acidic organophosphorus extractant to the hydroxyoxime extractant is (0.1-10):1.

[0021] Preferably, the acidic organophosphorus extractant is selected from one or more of P204, P507, and Cyanex 272.

[0022] Preferably, the hydroxyoxime extractant is selected from one or more α-hydroxyoxime extractants containing long-chain alkyl groups.

[0023] More preferably, the hydroxyoxime extractant is 5,8-diethyl-7-hydroxy-dodecane-6-oxime.

[0024] Preferably, the synergistic extractant is prepared by diluting an acidic organophosphorus extractant and a hydroxyoxime extractant with a diluent, wherein the volume concentration of the extractant is 10-60%.

[0025] Preferably, the diluent is selected from any one or more of 5# solvent oil, 260# solvent oil, and sulfonated kerosene.

[0026] Preferably, in step S5, a saponified synergistic extractant is used to perform nickel-cobalt extraction on the third leachate.

[0027] More preferably, the method includes: using a saponifying agent to saponify the synergistic extractant to obtain saponified waste liquid and saponified organic phase.

[0028] More preferably, it includes: using the saponified organic phase to perform nickel-cobalt extraction on the third leachate.

[0029] More preferably, the method includes adding the saponification waste liquid as a precipitating and converting agent for iron removal by alum precipitation to the first oxidized leachate.

[0030] Preferably, the saponifying agent is an alkaline solution containing one or more of sodium, potassium, and ammonia. Further, the saponifying agent is one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, and ammonium carbonate. Preferably, the saponification rate during the saponification treatment is 10-70%.

[0031] Preferably, step S3 further includes controlling the molar ratio of the total amount of alkali metal ions to the total amount of iron and scandium in the first oxidized leachate to be (1.1~5.5):1.

[0032] Preferably, in step S5, when performing nickel-cobalt extraction, the equilibrium pH of the aqueous phase of the extraction reaction is 3 to 6.

[0033] Preferably, step S5 includes: performing nickel-cobalt multi-stage countercurrent extraction on the third leachate to obtain a nickel-cobalt supported organic phase;

[0034] Preferably, step S5 further includes: performing multi-stage washing on the extracted organic phase to produce a sulfuric acid-containing organic phase washing solution.

[0035] Preferably, step S5 further includes: performing multi-stage back-extraction on the washed extract-loaded organic phase to obtain a nickel and cobalt solution, so as to separate and purify the nickel and cobalt product.

[0036] Preferably, the extraction stage has 3 to 6 extraction stages, the flow ratio of the aqueous phase to the organic phase is (0.1 to 10):1, the extraction temperature is 20 to 60°C, and the extraction time for each stage is 3 to 6 minutes.

[0037] Preferably, the washing section has 2 to 5 washing stages, and the washing solution is a dilute sulfuric acid solution with a concentration of 0.01 to 0.5 mol / L.

[0038] Preferably, the number of back-extraction stages in the back-extraction section is 3 to 8, and the back-extraction solution is sulfuric acid with a concentration of 0.5 to 5 mol / L.

[0039] Preferably, in step S1, the sulfuric acid solution is a dilute sulfuric acid solution with a concentration of 0.1–3 mol / L.

[0040] Preferably, the dilute sulfuric acid solution is prepared using an organic phase washing liquid containing sulfuric acid produced during the washing section of nickel-cobalt extraction.

[0041] Preferably, in step S1, when sulfuric acid is added for leaching, the liquid-solid ratio of the leaching system is 5:1 to 2:1, the pH value is 1.0 to 6.5, the leaching temperature is 15 to 45°C, and the leaching time is 5 to 50 min.

[0042] Preferably, step S3 further includes: adjusting the pH of the first oxidized leachate to 0.5-3.0 and the temperature to 40-95°C; and controlling the precipitation time to 40-400 min.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] According to one embodiment of the present invention, after sulfuric acid leaching, the sulfuric acid leachate is subjected to stepwise oxidation. The first oxidation treatment oxidizes ferrous iron to ferric iron, thereby facilitating the formation of vanadium-iron mixtures during vanadium precipitation. Simultaneously, scandium co-precipitation enrichment is achieved during vanadium precipitation. The vanadium-precipitated solution (i.e., the nickel-cobalt solution purified after iron and scandium removal) undergoes a second oxidation treatment, oxidizing ferrous manganese to tetravalent manganese and forming manganese dioxide precipitate, which is then separated and recovered. For the manganese-purified leachate (i.e., the third leachate after manganese removal), a novel synergistic extraction system is constructed using acidic organophosphorus extractants and hydroxyoxime extractants for nickel-cobalt extraction, whereby nickel and cobalt are directly extracted into the organic phase. This invention improves nickel-cobalt extraction efficiency, reduces the amount of neutralizing alkali used, and enables nickel-cobalt extraction and separation from impurities at lower pH levels. Attached Figure Description

[0045] Figure 1 This is a schematic flowchart of a method for nickel-cobalt co-extraction and its separation from scandium-manganese in one embodiment of the present invention. Detailed Implementation

[0046] The technical solution of the present invention will be clearly and completely described below with reference to embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0047] As described above, the inventors recognize that existing nickel-cobalt extraction processes still need improvement, especially for the separation of nickel-cobalt and scandium-manganese. For example, when using the reduction leaching-goethite method, the reduction leaching makes manganese divalent, resulting in a high manganese content in the nickel-cobalt solution, which affects nickel-cobalt extraction and increases the difficulty of the next step of nickel-cobalt extraction.

[0048] Based on this, the inventors first proposed a method for nickel-cobalt extraction and its separation from scandium and manganese. This method involves the stepwise oxidation and precipitation separation and recovery of metal ions Fe(II) and Mn(II), coupled with vanadium precipitation for iron removal and scandium enrichment, and the extraction of nickel and cobalt using an acidic organic extractant. After acid leaching of the nickel-cobalt-containing material, the variable-valence metal ions are oxidized stepwise. First, ferrous iron is oxidized to ferric iron for vanadium precipitation and iron removal. Iron alum precipitates, simultaneously enriching scandium. The vanadium-precipitated solution is further oxidized to form manganese dioxide precipitate, which is then separated and recovered. The purified leachate, after manganese removal, is then subjected to efficient nickel-cobalt extraction using an acidic organic extractant, preferably a saponified extractant, thus improving the extraction efficiency and reducing the extraction difficulty. This invention achieves the separation of nickel and cobalt from scandium and manganese.

[0049] The inventors recognized that when using acidic organophosphorus extractants for extraction and separation, such as saponified acidic organophosphorus extractants P204, P507, and Cyanex 272 (e.g., P204 extraction-P507 cobalt extraction-Cyanex 272 deep extraction), there are problems such as high extraction equilibrium pH, the need for large amounts of neutralizing alkali, and low extraction and separation efficiency. Furthermore, removing iron and aluminum by precipitation before extraction generates large amounts of salt- and acid-containing waste liquid that cannot be recycled. Moreover, P204 and P507 have high calcium extraction capabilities; when calcium is co-extracted into the organic phase, calcium sulfate precipitates easily form in the sulfuric acid system. Therefore, the extraction system must include a calcium removal process, which also reduces extraction efficiency.

[0050] Further research by the inventors revealed that extractant molecules exhibit significant extraction performance only when the hydroxyl group is at the α-position. Therefore, a synergistic extraction system, namely a synergistic extractant, is formed by combining an acidic organophosphorus extractant and an α-hydroxyoxime extractant. Using this synergistic extractant to extract nickel and cobalt, the extraction performance and separation selectivity are improved by utilizing the more spatially stable extractant formed by the acidic organophosphorus extractant and the α-hydroxyoxime extractant. Nickel and cobalt extraction and separation from impurities can be achieved at a lower pH, saving on neutralizing alkali.

[0051] Based on this, the present invention proposes a method for nickel-cobalt co-extraction and its separation from scandium and manganese. Scandium is enriched by stepwise oxidation of variable valence metal ions Fe(II) and Mn(II) coupled with iron-vanadium method for iron removal and co-precipitation. This achieves the separation and recovery of metallic iron, scandium and manganese. Furthermore, the improved co-extraction system is used to extract nickel and cobalt from the purified leachate after iron removal and scandium-manganese removal, which improves the nickel-cobalt extraction efficiency, reduces the amount of neutralizing alkali used, and lowers the extraction difficulty.

[0052] The present invention provides a method for nickel-cobalt co-extraction and its separation from scandium-manganese, comprising the following steps:

[0053] Step S1: Add sulfuric acid solution to the nickel-cobalt-containing material for leaching, and separate the solid and liquid to obtain the first leachate;

[0054] Step S2: A first oxidant is introduced into the first leachate to perform a first oxidation, which oxidizes ferrous iron to ferric iron, and a leachate with the first oxidation is obtained.

[0055] Step S3: The first oxidized leachate is subjected to alum precipitation and iron removal using the iron-vanadium ore method, followed by solid-liquid separation to obtain scandium-containing iron-vanadium slag and a second leachate after iron and scandium removal.

[0056] Step S4: Add a second oxidant to the second leachate to perform a second oxidation, oxidizing divalent manganese to tetravalent manganese, and then separate the solid and liquid to obtain manganese oxide precipitate residue and a third leachate after manganese removal.

[0057] Step S5: The third leachate is subjected to nickel-cobalt extraction using a synergistic extractant prepared from an acidic organophosphorus extractant and a hydroxyoxime extractant to obtain a nickel-cobalt-loaded organic phase. The phase is then washed and back-extracted to obtain a nickel-cobalt solution, which is then separated and purified to obtain the nickel-cobalt product.

[0058] After sulfuric acid leaching, the sulfuric acid leachate undergoes stepwise oxidation of variable-valence metal ions Fe(II) and Mn(II). The first oxidation treatment oxidizes ferrous iron to ferric iron, which facilitates the formation of vanadium iron during vanadium precipitation. Simultaneously, scandium co-precipitation enrichment is achieved during vanadium precipitation. The vanadium-precipitated solution (i.e., the nickel-cobalt solution purified after iron and scandium removal) undergoes a second oxidation treatment, oxidizing ferrous manganese to tetravalent manganese and forming manganese dioxide precipitate, which is then separated and recovered, thus achieving the separation and recovery of ferrous iron and scandium and manganese. For the manganese-purified leachate, i.e., the third leachate after manganese removal, a synergistic extraction system consisting of an acidic organophosphorus extractant and a hydroxyoxime extractant is used for nickel-cobalt extraction. This improves the nickel-cobalt extraction efficiency, reduces the amount of neutralizing alkali used, and allows for nickel-cobalt extraction and separation from impurities at a lower pH. Furthermore, the nickel-cobalt extraction is a direct extraction.

[0059] In step S1, to further improve the leaching effect of nickel, cobalt, scandium, iron, and manganese, preferably, the liquid-solid ratio of the sulfuric acid leaching system is controlled to be 5:1 to 2:1; the pH value is 1.0 to 6.5, more preferably 2.0 to 5.0. Preferably, the leaching temperature is 15 to 45°C, more preferably 20 to 40°C. The leaching time is preferably 5 to 50 minutes. Furthermore, the sulfuric acid solution is preferably a dilute sulfuric acid solution with a concentration of 0.1 to 3 mol / L. Preferably, the dilute sulfuric acid solution is prepared using waste dilute sulfuric acid solution from the nickel-cobalt extraction washing section and a sulfuric acid-containing organic phase washing liquid to achieve reagent recycling; for example, it can be prepared using waste dilute sulfuric acid solution, water, and concentrated sulfuric acid.

[0060] To improve the stepwise oxidation efficiency of variable valence metal ions Fe(II) and Mn(II), steps S2 and / or S4 further include adjusting the pH and temperature of the sulfuric acid leaching solution.

[0061] Further, in step S2, the pH of the first leachate is adjusted to 1.0–4.5, such as 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, etc., preferably pH 2.0–4.0. The temperature of the first leachate is adjusted to 20–45°C, such as 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, etc., preferably 30–40°C.

[0062] Further, in step S4, the pH of the second leachate is adjusted to 3.0–6.5, for example, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, etc., preferably pH 4.0–6.0. ​​The temperature of the second leachate is adjusted to 45–95°C, for example, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, etc., preferably 55–85°C.

[0063] After acid leaching at atmospheric pressure, the pH and temperature of the sulfuric acid leachate are adjusted, and an oxidizing agent is introduced to utilize the generated intermediate products such as SO5. •− The strong oxidizing effect of free radical species, by taking advantage of the difference in the effects of temperature and solution pH on the oxidation sequence of Fe(II) and Mn(II) ions, can more effectively achieve the stepwise oxidation of divalent iron and manganese in solution, thus realizing precipitation and separation.

[0064] When adjusting the pH, sulfuric acid or an alkaline neutralizing agent is preferably added to avoid introducing other impurities. The alkaline neutralizing agent is preferably any one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, and ammonium carbonate. Furthermore, the reaction time for the first oxidation is preferably controlled within 2–20 minutes. The reaction time for the second oxidation is preferably controlled within 5–30 minutes.

[0065] Oxidation is performed stepwise by introducing a first oxidant and a second oxidant. Preferably, oxygen or air is used as the first oxidant. SO2 and oxygen / air are used as the second oxidant to achieve complete oxidation of divalent manganese and simplify the system. To further improve the oxidation and separation of manganese, the volume fraction ratio of SO2 to oxygen in the second oxidant is controlled to be 3–20:100.

[0066] Introducing oxygen or air to oxidize ferrous iron is beneficial for vanadium precipitation and iron removal. Introducing SO2 and oxygen / air into the solution after alum precipitation allows ferrous manganese in the solution to be fully oxidized, rapidly oxidized to tetravalent manganese to form manganese dioxide precipitate. After the reaction is completed, manganese can be removed / recovered by liquid-solid separation, realizing the recovery of iron, scandium and manganese. Then, nickel-cobalt extraction can be carried out based on the third leaching solution after removing iron, scandium and manganese, which can improve the extraction efficiency.

[0067] In some embodiments, to further improve the stepwise oxidation efficiency of metal ions Fe(II) and Mn(II), a corresponding catalyst is added in step S2 and / or step S4. In step S2, a Cu(II)-containing reagent is preferably added as a catalyst for the first oxidation reaction. In step S4, a Fe(III)-containing reagent is preferably added as a catalyst for the second oxidation reaction. To further improve the (iron) oxidation efficiency, the concentration of Cu(II) ions in the Cu(II)-containing reagent is controlled to be 0.005–0.05 mol / L. To further improve the (manganese) oxidation efficiency, the concentration of Fe(III) ions in the Fe(III)-containing reagent is 0.001–0.1 mol / L.

[0068] In step S3 of this invention, the ferrous sulfate method is used to remove iron and scandium from the leachate after the first oxidation. First, ferrous iron is rapidly oxidized to ferric iron, then the ferric ions are precipitated as alum and co-precipitated with scandium to enrich the precipitate, forming alum-type precipitate doped with or adsorbing scandium, thereby achieving iron-scandium separation and recovery. Compared with conventional acid leaching-iron-aluminum removal processes, this invention achieves better iron removal and scandium enrichment, and eliminates the need to raise the pH value during the iron-aluminum removal stage to co-precipitate and generate iron-aluminum-scandium hydroxide for scandium removal. The resulting scandium-rich precipitate has a higher crystal structure, is easier to precipitate, wash, and filter, and has a lower scandium loss rate. Furthermore, after stepwise oxidation in this invention, iron-vanadium scandium precipitation and manganese oxide precipitation can be formed at higher acidity, further reducing the need for alkali neutralization.

[0069] In step S3, to further improve the efficiency of vanadium precipitation and iron removal, preferably, the pH and / or temperature of the leachate from the first oxidation process are adjusted during the co-precipitation enrichment of vanadium and scandium for iron removal. Specifically, the pH of the leachate from the first oxidation process is adjusted to 0.5–3.0, preferably 1.0–1.5. The temperature of the leachate from the first oxidation process is adjusted to 40–95°C, preferably 60–90°C. Furthermore, the precipitation time is preferably controlled within 40–400 min. To accelerate iron removal and ensure a more complete reaction, stirring can be performed during the vanadium precipitation and iron removal process, with a stirring intensity preferably of 100–350 r / min. Additionally, sulfuric acid or an alkaline neutralizing agent is preferably added when adjusting the pH; the alkaline neutralizing agent is preferably any one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, and ammonium carbonate.

[0070] When using the vanadium precipitation method for iron removal, a precipitating agent is added, preferably a reagent containing one or more of the following ions: ammonia, sodium, and potassium, such as one or more of the following solutions: ammonium sulfate, sodium sulfate, and potassium sulfate. To further improve the efficiency of vanadium precipitation and iron removal, the molar ratio of the total amount of ammonia, sodium, and potassium ions in the precipitating agent to the total amount of scandium and iron in the first oxidized leachate is preferably controlled to be 1.1–5.5:1.

[0071] In some embodiments, the saponification waste liquid after saponification is added to the leachate of the first oxidation process as a precipitating agent for vanadium precipitation and iron removal. The inventors recognize that the saponification waste liquid generated during the extractant saponification process is ammonia-, sodium-, and potassium-containing waste liquid, specifically ammonium sulfate, sodium sulfate, and potassium sulfate. By recycling this saponification waste liquid generated during the nickel-cobalt extraction saponification process, and using the (ammonium, sodium, and potassium) alum ore formation method to remove iron from the leachate, a precipitate of alum type (mainly potassium ferroalloy, sodium ferroalloy, and ammonium ferroalloy) doped with or adsorbing scandium and a nickel-cobalt-containing solution are formed. This simultaneously removes iron impurities and enriches scandium, thus recycling the elements and reagents.

[0072] In step S5, during nickel-cobalt extraction, a synergistic extraction system consisting of an acidic organophosphorus extractant and a hydroxyoxime extractant is used to improve the extraction performance and separation selectivity of the extractant, further increasing the nickel-cobalt extraction efficiency and lowering the pH of the extraction reaction. For example, the equilibrium pH of the aqueous phase in the extraction reaction can be 3-6. The acidic organophosphorus extractant is preferably selected from one or more of di(2-ethylhexyl) phosphate (P204), 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (P507), and di(2,4,4-trimethylpentyl)phosphonic acid (Cyanex272). The hydroxyoxime extractant is preferably selected from one or more of α-hydroxyoxime extractants containing long-chain alkyl groups (aliphatic α-hydroxyoximes); more preferably 5,8-diethyl-7-hydroxy-dodecane-6-oxime ((Lix63)).

[0073] To further improve the extraction efficiency of the synergistic extraction system, the molar ratio of acidic organophosphorus extractant to hydroxyoxime extractant is preferably controlled to be 0.1–10:1, for example, 0.1:1, 0.5:1, 1:1, 4:1, 6:1, 8:1, 10:1, etc. The synergistic extraction system can be prepared using acidic organophosphorus extractant, hydroxyoxime extractant, and diluent. Further, the volume concentration of the extractant in the synergistic extraction system is preferably 10–60%. The diluent can be selected from any one or more of 5# solvent oil, 260# solvent oil, and sulfonated kerosene, more preferably alkane diluents, to improve the solubility of the extractant.

[0074] In some embodiments, to further improve the nickel-cobalt extraction and separation efficiency, a saponifying agent is used to saponify the synergistic extractant. After saponification, a saponification waste liquid and a saponified organic phase are obtained. Using the saponified synergistic extractant, i.e., the saponified organic phase, to extract nickel and cobalt from the third leaching solution further improves the nickel-cobalt extraction and separation efficiency. The saponification waste liquid is added to the first oxidation leaching solution as a precipitating agent for vanadium precipitation and iron removal, achieving element recycling. Furthermore, during the saponification treatment, the saponification rate is preferably controlled to be 10-70%. The saponifying agent is an alkaline solution containing one or more of sodium, potassium, and ammonia, and the resulting saponification waste liquid contains the ions mentioned above. Preferably, the saponifying agent is one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, and ammonium carbonate.

[0075] When performing nickel-cobalt extraction, a multi-stage countercurrent extraction, washing, and back-extraction process is preferred. Specifically, this includes: multi-stage countercurrent extraction to obtain a nickel-cobalt-loaded organic phase; multi-stage washing of the extracted organic phase to produce a sulfuric acid-containing organic phase washing solution; and multi-stage back-extraction of the washed nickel-cobalt-loaded organic phase.

[0076] To achieve more efficient nickel-cobalt extraction, the process parameters for each stage were optimized. Specifically, in the extraction stage: the preferred number of extraction stages is 3–6; the ratio of the organic phase to the aqueous phase in the saponification extraction is preferably 0.1–10:1; the preferred extraction temperature for each stage is 20–60℃; the preferred extraction time for each stage is 3–6 min; and the equilibrium pH of the aqueous phase in the extraction reaction can be 3–6, preferably 3.5–5.5, as extraction under low pH conditions significantly reduces the amount of alkali used for neutralization. In the washing stage: the preferred number of washing stages is 2–5; the washing solution for the extracted organic phase is preferably a dilute sulfuric acid solution with a concentration of 0.01–0.5 mol / L. In the back-extraction stage: the preferred number of back-extraction stages is 3–8; the preferred back-extraction solution is sulfuric acid with a concentration of 0.5–5 mol / L.

[0077] In some embodiments, reference is made to Figure 1 As shown, the nickel-cobalt-containing material being processed is nickel-cobalt hydroxide produced from laterite nickel ore, and the specific steps include:

[0078] Step S11: Add sulfuric acid solution to nickel-cobalt hydroxide produced from laterite nickel ore for leaching to leach nickel, cobalt, scandium, iron, and manganese. Perform a first solid-liquid separation on the leached slurry to obtain a first leaching residue and a first leaching solution.

[0079] Step S21: Introduce oxygen or air into the first leachate to perform a first oxidation treatment, thereby oxidizing ferrous ions to ferric ions to obtain a leachate with the first oxidation.

[0080] Step S31: Add saponification waste liquid to the first oxidized leachate for precipitation and iron removal. Use the iron alum ore method to remove scandium from the first oxidized leachate, forming an iron alum-type precipitate with adsorbed or doped scandium and a nickel-cobalt-containing solution. Perform a second solid-liquid separation on the alum precipitation slurry to obtain scandium-containing iron-vanadium slag (processed to obtain scandium product) and a second leachate purified by removing scandium.

[0081] Step S41: SO2 and oxygen / air are added to the second leaching solution to carry out the second oxidation treatment, where divalent manganese is oxidized to tetravalent manganese. Manganese separation is achieved through oxidation precipitation. The slurry after oxidation precipitation is subjected to a third solid-liquid separation to obtain oxidation precipitation residue (manganese product obtained through treatment) and a third leaching solution purified by removing manganese (i.e., purified nickel-cobalt solution).

[0082] Step S51: Dilute the acidic organophosphorus extractant and the hydroxyoxime extractant with a diluent to obtain a synergistic extractant. Saponify the synergistic extractant with a saponifying agent to obtain a saponified organic phase and a saponified waste liquid (containing one or more of ammonium, sodium, and potassium). Use the saponified organic phase for nickel-cobalt extraction. Wash and back-extract the nickel-cobalt loaded organic phase to obtain the nickel-cobalt product. Add the saponified waste liquid generated by saponification to the leachate of the first oxidation.

[0083] In this embodiment, for nickel-cobalt hydroxide produced from laterite nickel ore, after sulfuric acid leaching, variable valence metal ions are oxidized stepwise. After iron is removed, scandium is enriched and manganese is separated and recovered by the iron-vanadium method, a saponification synergistic extraction system is used for nickel-cobalt extraction, and the saponification waste liquid is recycled. The process involves oxidizing the nickel-cobalt-sulfuric acid leaching solution with a first oxidant, oxygen / air, under low pH conditions. This rapidly oxidizes ferrous iron (Fe2+) to ferric iron (Fe3+), facilitating the formation of iron alum in the next step. The alum-precipitated solution is then further oxidized with a second oxidant, SO2, and oxygen / air, rapidly oxidizing manganese (Mn2+) to tetravalent manganese. This forms manganese dioxide precipitate, which is then separated and recovered via liquid-solid separation. The extractant is saponified using an alkaline solution containing ammonia, sodium, or potassium. Saponification further increases the efficiency of nickel-cobalt extraction and separation. The saponification wastewater containing ammonia, sodium, or potassium salts generated during the process is recycled to remove iron from the alum, which facilitates the precipitation of vanadium and iron, co-precipitation enrichment of scandium, and the removal of scandium and iron. This process achieves partial reagent recycling and comprehensively realizes the separation, enrichment, and recovery of nickel, cobalt, manganese, and scandium.

[0084] The invention and its effects are further illustrated below with reference to specific embodiments.

[0085] In the following examples, the raw material laterite nickel ore used has the following composition: nickel 1.18%, cobalt 0.15%, aluminum 3.5%, manganese 0.55%, iron 40.0%, magnesium 2.0%, calcium 2.0%, and scandium 0.0033%. The nickel-cobalt hydroxide produced from laterite nickel ore has the following composition: nickel 38.6%, cobalt 3.16%, aluminum 2.41%, manganese 5.37%, iron 1.91%, magnesium 2.07%, calcium 0.33%, and scandium 0.035%.

[0086] Example 1

[0087] 1) 1000g of nickel-cobalt hydroxide produced from laterite nickel ore was leached in a 0.3 mol / L dilute sulfuric acid solution. The dilute sulfuric acid solution was prepared by adding concentrated sulfuric acid to the dilute sulfuric acid waste solution generated from the nickel-cobalt extraction and washing section. During leaching, the liquid-to-solid ratio was 4:1, the pH value was 2.5, the temperature was 40℃, and the leaching time was 20min. The sulfuric acid leachate of nickel-cobalt hydroxide was obtained by filtration, which is the first leachate.

[0088] 2) Add a neutralizing agent or sulfuric acid to the first leachate to adjust the pH of the first leachate to 1.5, set the temperature to 30°C, add 0.005 mol / L copper sulfate solution as a catalyst for the oxidation reaction, and pass air into the slurry to oxidize ferrous iron. The reaction time is 8 min to obtain an oxidized leachate.

[0089] 3) Sulfuric acid is added to the oxidized leachate to control the pH value of the oxidized leachate at 1.5, the temperature of the leachate at 40°C, and the stirring intensity at 300 r / min. Saponification waste liquid containing alkali metal ions is added to precipitate alum and remove iron and scandium, ensuring the molar ratio of total alkali metal ions to total iron and scandium metal elements is 3.2:1. The precipitation time is 50 min. Filtration yields a scandium-rich iron-vanadium second leachate. Testing shows that the scandium enrichment and recovery rate reaches 95.9%. The saponification waste liquid can be the sodium-containing saponification waste liquid of this embodiment, or it can be the ammonia, sodium, and potassium-containing saponification waste liquid generated from the saponification process of other embodiments.

[0090] 4) Add an alkaline neutralizing agent to the second leachate to adjust its pH to 3.5. Then, introduce SO2 and oxygen into the leachate for oxidation to fully oxidize divalent manganese. The volume fraction ratio of SO2 to oxygen is 5:100, the temperature is 45℃, and 0.001mol / L ferric sulfate solution is added as a catalyst to accelerate the oxidation reaction. The reaction time is 20min. Filter to obtain manganese oxide slag and the third leachate. The manganese enrichment and recovery rate is 95.5%.

[0091] 5) Prepare a No. 5 solvent oil organic solution (synergistic extractant) of organophosphate extractant Cyanex272 and hydroxyoxime extractant Lix63. The total concentration of Cyanex272 and Lix63 in the synergistic extractant is 30% (v / v), and the molar ratio of Cyanex272 to Lix63 is 2:1. Saponify the above extractant solution, wherein the saponifying agent is 2 mol / L sodium hydroxide, and the saponification rate of Cyanex272 is 50%, to obtain a saponified organic phase and a saponified waste liquid containing sodium ions.

[0092] 6) The saponified organic phase described above was used for nickel-cobalt extraction and separation in the third leaching solution. The extraction stage involved four stages of countercurrent extraction at 20°C, with an organic phase to aqueous phase ratio of 10:1, an equilibrium pH of 4.5 in the aqueous phase, and an extraction time of 4 min, yielding an extract-loaded organic phase (nickel-cobalt loaded organic phase). The washing stage consisted of four stages, with the washing solution for the extract-loaded organic phase being a 0.1 mol / L dilute sulfuric acid solution at 30°C. The washed extract-loaded organic phase was then subjected to six stages of back-extraction using a 2 mol / L sulfuric acid solution at 40°C.

[0093] Testing revealed that the total recovery rate of the extraction-washing-back-extraction process was 98.1% for nickel and 98.5% for cobalt.

[0094] Example 2

[0095] 1) 1000g of nickel-cobalt hydroxide produced from laterite nickel ore was added to a 0.5 mol / L dilute sulfuric acid solution for leaching. The dilute sulfuric acid solution was prepared by adding concentrated sulfuric acid to the dilute sulfuric acid waste solution generated from the nickel-cobalt extraction and washing section. The liquid-to-solid ratio was 2:1, the pH value was 1.0, the temperature was 30℃, and the leaching time was 20min. The first leachate was obtained by filtration.

[0096] 2) Add a neutralizing agent or sulfuric acid to the first leachate to adjust the pH of the sulfuric acid leachate of nickel-cobalt hydroxide to 2.0, the temperature to 30°C, add 0.01 mol / L copper sulfate solution as a catalyst for the oxidation reaction, and pass air through the slurry to oxidize ferrous iron for 10 min to obtain the oxidized leachate.

[0097] 3) Add sulfuric acid to the oxidized leachate to control the pH value of the leachate at 1.0, control the temperature of the leachate at 75°C, and the stirring intensity at 200 r / min. Add saponification waste liquid containing alkali metal ions to precipitate alum and remove iron and scandium, so that the molar ratio of the total amount of alkali metal ions to the total amount of iron and scandium metal elements is 1.5:1. The precipitation time is 100 min. Filter to obtain scandium-rich iron-vanadium second leachate. The scandium enrichment and recovery rate reaches 95.1%.

[0098] 4) Add an alkaline neutralizing agent to the second leachate to adjust its pH to 4.0. Then, circulate SO2 and air through the leachate for oxidation to fully oxidize divalent manganese. The volume fraction ratio of SO2 to oxygen is 15:100, the temperature is 55℃, and 0.005 mol / L ferric sulfate solution is added as a catalyst to accelerate the oxidation reaction. The reaction time is 20 min. Filter to obtain manganese oxide slag and the third leachate. The manganese enrichment and recovery rate reaches 95.8%.

[0099] 5) Prepare a 260# solvent oil solution containing 25% organophosphate extractant P507 and hydroxyoxime extractant Lix63, wherein the molar ratio of P507 to Lix63 is 1:1; saponify the above extractant solution, wherein the saponifying agent is 4 mol / L ammonia water, the saponification rate is 40%, and saponified organic phase and saponified waste liquid containing ammonium ions are obtained.

[0100] 6) The saponified organic phase was used to perform nickel-cobalt extraction separation in the third leaching solution; wherein, the extraction was carried out in 6 stages of countercurrent extraction at a temperature of 40℃, the ratio of the saponified organic phase to the aqueous phase was 2:1, and the equilibrium pH of the aqueous phase was 3.5; the washing stage consisted of 4 stages, and the washing solution for the organic phase loaded with extraction was a 0.2 mol / L dilute sulfuric acid solution; the washed organic phase loaded with extraction was subjected to 3 stages of back-extraction using a 1 mol / L sulfuric acid solution.

[0101] Testing revealed that the total recovery rates of extraction-washing-back-extraction were 98.0% for nickel and 98.6% for cobalt.

[0102] Example 3

[0103] 1) 1000g of nickel-cobalt hydroxide produced from laterite nickel ore was added to a 1 mol / L dilute sulfuric acid solution for leaching. The dilute sulfuric acid solution was prepared by adding concentrated sulfuric acid to the dilute sulfuric acid waste solution generated from the nickel-cobalt extraction and washing section. The liquid-to-solid ratio was 5:1, the pH value was 5.0, the temperature was 40℃, and the leaching time was 20min. The first leachate was obtained by filtration.

[0104] 2) Add a neutralizing agent or sulfuric acid to the leachate to adjust the pH of the sulfuric acid leachate of nickel-cobalt hydroxide to 3.0, the temperature to 40℃, add 0.05mol / L copper sulfate solution as a catalyst for the oxidation reaction, and pass air through the slurry to oxidize ferrous iron for 10 min to obtain the oxidized leachate.

[0105] 3) Add sulfuric acid to the oxidized leachate to control the pH value of the leachate at 3.0, control the temperature of the leachate at 90℃ and the stirring intensity at 200 r / min, add saponification waste liquid containing potassium ions to precipitate alum and remove iron and scandium, so that the molar ratio of the added potassium to the total amount of iron and scandium metal elements in the leachate is 2.5:1, the precipitation time is 200 min, and filter to obtain scandium-rich iron-vanadium second leachate, with the scandium enrichment and recovery rate reaching 95.6%.

[0106] 4) Add an alkaline neutralizing agent to the second leachate to adjust its pH to 5.0. Then, circulate SO2 and oxygen into the leachate for oxidation to fully oxidize divalent manganese. The volume ratio of SO2 to oxygen is 20:100, the temperature is 55℃, and 0.05 mol / L ferric sulfate solution is added as a catalyst to accelerate the oxidation reaction. The reaction time is 30 min. Filter to obtain manganese oxide slag and the third leachate. The manganese enrichment and recovery rate reaches 95.9%.

[0107] 5) Prepare a sulfonated kerosene solution containing 40% organophosphate extractant P204 and hydroxyoxime extractant Lix63, with a molar ratio of P204:Lix63 of 1:1; use the above extractant solution as a saponifying agent with a 2 mol / L potassium carbonate solution, achieving a saponification rate of 20%, to obtain a saponified organic phase and a saponified waste liquid containing potassium ions.

[0108] 6) The saponified organic phase was used to extract and separate nickel and cobalt in the third leaching solution. The extraction was carried out by four stages of countercurrent extraction at a temperature of 40°C. The ratio of the saponified organic phase to the aqueous phase was 1:1, and the equilibrium pH of the aqueous phase was 3.0. The washing stage consisted of four stages, and the washing solution for the organic phase loaded with extraction was a 0.2 mol / L dilute sulfuric acid solution. The washed organic phase loaded with extraction was subjected to six stages of back-extraction with a 3 mol / L sulfuric acid solution. The total recovery rate of extraction-washing-back-extraction was 98.5% for nickel and 98.7% for cobalt.

[0109] Example 4

[0110] 1) 1000g of nickel-cobalt hydroxide produced from laterite nickel ore was added to a 2 mol / L dilute sulfuric acid solution for leaching. The dilute sulfuric acid solution was prepared by adding concentrated sulfuric acid to the dilute sulfuric acid waste solution generated from the nickel-cobalt extraction and washing section. The liquid-to-solid ratio was 3.5:1, the pH value was 5.0, the temperature was 40℃, and the leaching time was 20min. The first leachate was obtained by filtration.

[0111] 2) Add a neutralizing agent or sulfuric acid to the leachate to adjust the pH of the sulfuric acid leachate of nickel-cobalt hydroxide to 3.0, the temperature to 40℃, add 0.1 mol / L copper sulfate solution as a catalyst for the oxidation reaction, and pass air through the slurry to oxidize ferrous iron for 5 min to obtain the oxidized leachate.

[0112] 3) Add sulfuric acid to the oxidized leachate to control the pH value of the leachate at 1.5, control the temperature of the leachate at 90℃ and the stirring intensity at 200 r / min, add saponification waste liquid to precipitate alum and remove iron and scandium, so that the molar ratio of the total amount of alkali metal ions to the total amount of iron and scandium metal elements is 4.5:1, the precipitation time is 300 min, and filter to obtain scandium-rich iron-vanadium second leachate, with the scandium enrichment and recovery rate reaching 96.1%.

[0113] 4) Add an alkaline neutralizing agent to the second leachate to adjust its pH to 5.0. Then, circulate SO2 and oxygen into the leachate for oxidation to fully oxidize divalent manganese. The volume fraction ratio of SO2 to oxygen is 20:100, the temperature is 85℃, and 0.05 mol / L ferric sulfate solution is added as a catalyst to accelerate the oxidation reaction. The reaction time is 20 min. Filter to obtain manganese oxide slag and the third leachate. The manganese enrichment and recovery rate reaches 96.2%.

[0114] 5) Prepare a sulfonated kerosene solution containing 40% organophosphate extractant Cyanex272, organophosphate extractant P507, and hydroxyoxime extractant Lix63, with a molar ratio of organophosphate extractant Cyanex272: organophosphate extractant P507: hydroxyoxime extractant Lix63 of 0.5:0.5:1; use the above extractant solution as a saponifying agent with a 4 mol / L ammonium carbonate solution, achieving a saponification rate of 40%, to obtain a saponified organic phase and a saponified waste liquid containing ammonium ions.

[0115] 6) The saponified organic phase was used to extract and separate nickel and cobalt in the third leachate. The extraction was carried out by 6 stages of countercurrent extraction at a temperature of 40°C. The ratio of the saponified organic phase to the aqueous phase was 0.5:1, and the equilibrium pH of the aqueous phase was 4.0. The washing stage consisted of 5 stages, and the washing solution for the organic phase loaded with the extraction was a 0.5 mol / L dilute sulfuric acid solution. The washed organic phase loaded with the extraction was then subjected to 6 stages of back-extraction using a 5 mol / L sulfuric acid solution.

[0116] Testing revealed that the total recovery rate of the extraction-washing-back-extraction process was 98.8% for nickel and 98.5% for cobalt.

[0117] Compared with existing technologies, this invention employs a stepwise oxidation coupled with Fe(II) and Mn(II) metal ions to remove iron and scandium, separate and enrich manganese, and uses a saponified synergistic extraction system for nickel-cobalt extraction, which has the following advantages:

[0118] (1) Leaching of nickel-cobalt hydroxide with sulfuric acid under normal pressure, adjusting the pH and temperature of the sulfuric acid leaching solution of nickel-cobalt hydroxide, introducing oxygen or air, and utilizing the intermediate products such as SO5 generated by the chemical reaction of the Fe(III)-S(IV) system. •− The strong oxidizing effect of free radical species is utilized to achieve the stepwise oxidation of ferrous iron and manganese in solution by taking advantage of the difference in the effects of temperature and solution pH on the oxidation sequence of Fe(II) and Mn(II) ions.

[0119] (2) First, ferrous iron is rapidly oxidized to ferric iron, and then ferric ions are precipitated and enriched with scandium. The precipitated alum is recycled from the ammonia-, sodium-, and potassium-containing waste liquid generated during the nickel-cobalt extraction and saponification process. The leaching solution is treated with (ammonium, sodium, and potassium) alum ore to remove iron, forming alum-type precipitates doped with or adsorbing scandium (mainly potassium ferric alum, sodium ferric alum, and ammonium ferric alum) and a nickel-cobalt-containing solution. At the same time, iron impurities are removed and scandium is enriched, and the elements are recycled. The resulting scandium-rich precipitate has a higher crystal structure, is easier to precipitate, wash, and filter, and has a low scandium loss rate. Moreover, the oxidized manganese and iron-vanadium scandium precipitates can be formed at higher acidity, reducing the need for alkali neutralization.

[0120] (3) Then, SO2 and oxygen or air are introduced into the solution after precipitation of alum, which is the nickel-cobalt solution purified by removing iron and scandium, so that the divalent manganese in the solution is rapidly oxidized to tetravalent manganese, forming manganese dioxide precipitate. After the reaction is completed, liquid-solid separation is carried out, and manganese can be removed and recovered by filtration.

[0121] (4) A synergistic extractant consisting of an acidic organophosphorus extractant and a hydroxyoxime extractant is used to extract nickel and cobalt. The inventors have found that the extractant molecules only exhibit significant extraction performance when the hydroxyl group is in the α-position. Therefore, a synergistic system consisting of a saponified acidic organophosphorus extractant and an α-hydroxyoxime extractant is used to extract nickel and cobalt. The extraction performance and separation selectivity are improved by forming a more spatially stable extractant with the acidic organophosphorus extractant and the α-hydroxyoxime extractant. Extraction can be carried out at a lower pH to achieve the extraction of nickel and cobalt and the separation of it from impurities. There is no need to add alkali to precipitate and remove impurities from iron and aluminum, thus saving neutralizing alkali.

[0122] (5) The nickel-cobalt extractant is saponified using an alkaline solution containing ammonia, sodium, and potassium. Saponification further increases the efficiency of nickel-cobalt extraction and separation. After saponification, a solution containing ammonium sulfate, sodium sulfate, or potassium sulfate is produced. The organic phase loaded with the extract is washed with a dilute sulfuric acid solution. The washing liquid can be used to prepare leaching sulfuric acid. The saponification waste liquid can also be recycled.

[0123] In summary, the method described in this invention has the advantages of high impurity separation efficiency, higher recovery rate of nickel, cobalt, manganese, and scandium, and low equipment investment and operating costs.

[0124] The description of this invention is given for illustrative and descriptive purposes only and is not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A method for nickel-cobalt synergistic extraction and its separation from scandium-manganese, characterized in that, include: Step S1: Add sulfuric acid solution to nickel-cobalt hydroxide for leaching, and separate the solid and liquid to obtain the first leachate; Step S2: Adjust the pH of the first leachate to 1.0-4.5 and the temperature to 20-45°C. Introduce a first oxidant into the first leachate to perform a first oxidation, oxidizing ferrous iron to ferric iron, and obtain a leachate with the first oxidation. The first oxidant is oxygen or air. Step S3: The first oxidized leachate is subjected to alum precipitation and iron removal using the iron-vanadium ore method, followed by solid-liquid separation to obtain scandium-containing iron-vanadium slag and a second leachate after iron and scandium removal. Step S4: Adjust the pH of the second leachate to 3.0-6.5 and the temperature to 45-95℃. Add a second oxidant to the second leachate for a second oxidation to oxidize divalent manganese to tetravalent manganese. Separate the solid and liquid to obtain manganese oxide precipitate and a third leachate after manganese removal. The second oxidant is SO2 and oxygen / air, wherein the volume fraction ratio of SO2 to oxygen is (3-20):

100. Step S5: The third leachate is subjected to nickel-cobalt extraction using a synergistic extractant to obtain a nickel-cobalt supported organic phase; wherein the synergistic extractant is prepared using an acidic organophosphorus extractant and a hydroxyoxime extractant.

2. The method for nickel-cobalt synergistic extraction and its separation from scandium-manganese according to claim 1, characterized in that, Step S2 also includes: adding a reagent containing divalent copper ions as a catalyst for the first oxidation reaction; Step S4 also includes adding a reagent containing ferric ions as a catalyst for the second oxidation reaction.

3. The method for nickel-cobalt synergistic extraction and its separation from scandium-manganese according to claim 2, characterized in that, In the reagent containing divalent copper ions, the concentration of divalent copper ions is 0.005–0.05 mol / L; The concentration of ferric ions in the reagent containing ferric ions is 0.001–0.1 mol / L.

4. The method for nickel-cobalt synergistic extraction and its separation from scandium-manganese according to claim 1, characterized in that, The molar ratio of the acidic organophosphorus extractant to the hydroxyoxime extractant is (0.1-10):1; The acidic organophosphorus extractant is one or more of P204, P507, and Cyanex272; The hydroxyoxime extractant is selected from one or more α-hydroxyoxime extractants containing long-chain alkyl groups.

5. The method for nickel-cobalt synergistic extraction and its separation from scandium-manganese according to claim 4, characterized in that, The hydroxyoxime extractant is 5,8-diethyl-7-hydroxy-dodecane-6-oxime.

6. The method for nickel-cobalt synergistic extraction and its separation from scandium-manganese according to claim 1 or 4, characterized in that, In step S5, nickel-cobalt extraction is performed on the third leachate using a saponified synergistic extractant; including: The synergistic extractant was saponified using a saponifying agent to obtain saponified waste liquid and saponified organic phase; The saponified organic phase is used to perform nickel-cobalt extraction on the third leachate; The saponification waste liquid is added to the first oxidation leachate as a precipitating and converting agent for iron removal by alum precipitation. The saponifying agent is an alkaline solution containing one or more of sodium, potassium, and ammonia.

7. The method for nickel-cobalt synergistic extraction and its separation from scandium-manganese according to claim 6, characterized in that, Step S3 further includes: controlling the molar ratio of the total amount of ammonia, sodium, and potassium ions to the total amount of iron and scandium elements in the first oxidized leachate to be (1.1~5.5):1; The saponifying agent is one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, and ammonium carbonate; during the saponification treatment, the saponification rate is 10-70%.

8. The method for nickel-cobalt synergistic extraction and its separation from scandium-manganese according to claim 4, characterized in that, In step S5, during nickel-cobalt extraction, the equilibrium pH of the aqueous phase of the extraction reaction is 3–6.

9. The method for nickel-cobalt synergistic extraction and its separation from scandium-manganese according to claim 8, characterized in that, Step S5 includes: performing multi-stage countercurrent extraction of nickel and cobalt on the third leachate; performing multi-stage washing on the extracted organic phase to generate a sulfuric acid-containing organic phase washing solution; and performing multi-stage back-extraction on the washed extracted organic phase to obtain nickel and cobalt solutions for separation and purification to obtain the nickel and cobalt product; wherein, The extraction stage has 3 to 6 stages, the flow ratio of aqueous phase to organic phase is (0.1 to 10):1, the extraction temperature is 20 to 60℃, and the extraction time for each stage is 3 to 6 min. The washing section has 2 to 5 washing stages, and the washing solution is a dilute sulfuric acid solution with a concentration of 0.01 to 0.5 mol / L. The back-extraction stage has 3 to 8 stages, and the back-extraction solution is sulfuric acid with a concentration of 0.5 to 5 mol / L.

10. The method for nickel-cobalt synergistic extraction and its separation from scandium-manganese according to claim 1 or 9, characterized in that, In step S1, the sulfuric acid solution is a dilute sulfuric acid solution with a concentration of 0.1–3 mol / L; The dilute sulfuric acid solution is prepared using an organic phase washing solution containing sulfuric acid produced during the washing section of nickel-cobalt extraction.

11. The method for nickel-cobalt synergistic extraction and its separation from scandium-manganese according to claim 1, characterized in that, In step S1, when sulfuric acid is added for leaching, the liquid-solid ratio of the leaching system is 5:1 to 2:1, the pH value is 1.0 to 6.5, the leaching temperature is 15 to 45°C, and the leaching time is 5 to 50 minutes.

12. The method for nickel-cobalt synergistic extraction and its separation from scandium-manganese according to claim 1, characterized in that, Step S3 further includes: adjusting the pH of the first oxidized leachate to 0.5-3.0 and the temperature to 40-95℃; and controlling the precipitation time to 40-400 min.

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