Separation and recovery method of scandium and nickel-cobalt-manganese

Abstract

The invention discloses a method for separating and recycling scandium from nickel, cobalt and manganese, and belongs to the technical field of metal production or refining. The method comprises the following steps: adding a sulfuric acid solution into the nickel-cobalt-containing material for leaching, and carrying out solid-liquid separation to obtain a first leachate; a first oxidizing agent is introduced into the first leachate for first oxidation, ferrous iron is oxidized into ferric iron, and first oxidized leachate is obtained; a salt solution is added into the first oxidized leachate for alum precipitation and iron removal, solid-liquid separation is carried out, and scandium-containing ferrovanadium slag and purified second leachate with iron and scandium removed are obtained; a second oxidizing agent is added into the second leaching solution for second oxidation, divalent manganese is oxidized into tetravalent manganese, solid-liquid separation is carried out, and manganese oxide precipitation residues and a third leaching solution obtained after manganese removal and purification are obtained; and carrying out nickel-cobalt extraction on the third leaching solution by adopting a saponified acidic organic extraction agent so as to separate and purify nickel and cobalt. According to the method, nickel and cobalt can be separated from scandium and manganese, and the nickel and cobalt extraction efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of metal production or refining technology, and in particular to a method for separating and recovering scandium from nickel, cobalt, and 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. The purpose of refining nickel-cobalt hydroxide is to remove impurities from the system to obtain nickel-cobalt metal or its compounds.

[0003] In addition to nickel and cobalt, nickel-cobalt hydroxide also contains iron and manganese. During the acid leaching reaction of nickel-cobalt hydroxide, the iron will enter the acid leaching solution along with the nickel and cobalt. Iron needs to be removed during the refining and separation process to obtain a pure nickel-cobalt product.

[0004] Iron ions are a major impurity in the separation and utilization of valuable metals, and the iron alum process is a commonly used method for iron removal. Iron ions in nickel-cobalt hydroxide leaching solutions exist in both divalent and trivalent states. Conventional iron alum processes suffer from the problem that the pH for oxidizing divalent iron is much higher than the pH for alum precipitation. Oxidants available 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.

[0005] Furthermore, a significant amount of nickel-cobalt hydroxide produced from laterite nickel ore contains scandium, a harmful impurity in nickel-cobalt smelting and also a rare earth resource. Due to the low concentration of scandium in the system, the removal and recovery of scandium using scandium precipitation alone results in low precipitation rates and difficulty in settling the precipitate. To address this issue, the inventors of this application achieved the removal and recovery of scandium from nickel-cobalt solutions by adjusting the pH value to 3.0 or higher during the iron-aluminum removal process, allowing scandium to co-precipitate with iron and aluminum, and then precipitate it as hydroxide. However, in practice, the inventors found that during the hydroxide co-precipitation process, the reaction endpoint is difficult to determine due to the special properties of aluminum hydroxide and scandium hydroxide dissolving in strong alkalis, 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. In addition, if the reaction is carried out at a high pH value, the loss of nickel, cobalt, and manganese in the slag increases. Based on this discovery, the inventors performed reductive leaching of a nickel-cobalt hydroxide slurry, followed by iron removal from the leaching solution using a goethite method. This resulted in the formation of a goethite-type precipitate with adsorbed or doped scandium, achieving scandium co-precipitation enrichment and separation of a nickel-cobalt-containing solution. However, further research revealed that the reductive leaching caused manganese to become divalent, resulting in a high manganese content in the nickel-cobalt solution. This affected nickel-cobalt extraction and increased the difficulty of subsequent nickel-cobalt extraction.

[0006] In view of this, it is necessary to improve the separation and recovery process of nickel, cobalt, scandium, iron and manganese. Summary of the Invention

[0007] According to one embodiment of the present invention, the objective is to provide a method for the separation and recovery of scandium from nickel, cobalt, and manganese. By performing stepwise oxidation coupled with vanadium precipitation to remove iron and enrich scandium through co-precipitation of variable-valence metals iron and manganese, and separating and recovering manganese from the precipitate, and using a saponified acidic organic extractant for nickel-cobalt extraction, the extraction efficiency is improved, the extraction difficulty is reduced, and the separation of nickel-cobalt from scandium and manganese is achieved.

[0008] The above objective can be achieved through the following technical solutions: According to one aspect of the present invention, a method for separating and recovering scandium from nickel, cobalt, and manganese is provided, comprising: Step S1: Add sulfuric acid solution to nickel-cobalt material for leaching, and separate solid and liquid to obtain the first leachate; 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. Step S3: Add a salt solution to the first oxidized leachate to precipitate alum and remove iron, and separate the solid and liquid to obtain scandium-containing iron-vanadium slag and a second leachate purified by removing iron and scandium; wherein the salt solution contains one or more of sodium, potassium and ammonia; 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 purified by removing manganese. Step S5: The third leachate is subjected to nickel-cobalt extraction using a saponified acidic organic extractant to separate and purify nickel-cobalt.

[0009] Preferably, step S2 further includes: adjusting the pH of the first leachate to 1.0-4.5 and the temperature to 20-45°C.

[0010] Preferably, step S4 further includes: adjusting the pH of the second leachate to 3.0-6.5 and the temperature to 45-95°C.

[0011] Preferably, the first oxidant is oxygen or air; the second oxidant is SO2 and oxygen / air.

[0012] Preferably, in the second oxidant, the volume fraction ratio of SO2 to oxygen is (3-20):100.

[0013] Preferably, step S2 further includes adding a Cu(II)-containing reagent as a catalyst for the first oxidation reaction.

[0014] More preferably, in the Cu(II)-containing reagent, the concentration of Cu(II) ions is 0.005–0.05 mol / L; Preferably, step S4 further includes adding a Fe(III)-containing reagent as a catalyst for the second oxidation reaction.

[0015] More preferably, the concentration of Fe(III) ions in the Fe(III)-containing reagent is 0.001–0.1 mol / L.

[0016] Preferably, when adjusting the pH, sulfuric acid or an alkaline neutralizing agent is added, wherein the alkaline neutralizing agent is any one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, and ammonium carbonate.

[0017] Preferably, the acidic organic extractant is at least two of P204, P507, and Cyanex 272.

[0018] More preferably, each acidic organophosphorus extractant accounts for no less than 10%.

[0019] Preferably, in step S5, the saponifying agent used in the saponification is one or more of ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and ammonium carbonate.

[0020] Furthermore, the saponification waste liquid contains one or more of ammonium sulfate, sodium sulfate, and potassium sulfate, and the saponification waste liquid is recycled as a salt solution to step S3.

[0021] Preferably, in step S5, the saponification rate is 10-70%.

[0022] Preferably, step S3 further includes: adjusting the pH of the first oxidized leachate to 0.5-3.0; adjusting the temperature of the first oxidized leachate to 40-95°C; and controlling the precipitation time to 40-400 min.

[0023] 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 elements in the solution to be (1.1~5.5):1.

[0024] Preferably, step S5 specifically includes: performing nickel-cobalt multi-stage countercurrent extraction on the third leachate using a saponified acidic organic extractant; using a dilute sulfuric acid solution as a washing liquid to perform multi-stage washing on the extracted organic phase to generate a sulfuric acid-containing organic phase washing liquid; and performing multi-stage back-extraction on the washed extracted organic phase.

[0025] Preferably, the extraction stage has 3 to 6 extraction stages, the extraction temperature for each stage is 20 to 60°C, and the extraction time for each stage is 3 to 6 minutes.

[0026] Preferably, the washing section has 2 to 5 washing stages, and the concentration of the dilute sulfuric acid solution used as the washing liquid is 1 to 10%.

[0027] Preferably, in step S1, the liquid-to-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.

[0028] Preferably, in step S1, the nickel-cobalt-containing material is nickel-cobalt hydroxide produced from laterite nickel ore.

[0029] Preferably, in step S1, the sulfuric acid solution is a dilute sulfuric acid solution.

[0030] More preferably, 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; Compared with the prior art, the present invention has the following beneficial effects: According to one embodiment of the present invention, after sulfuric acid leaching, the sulfuric acid leaching solution is subjected to stepwise oxidation. The first oxidation treatment oxidizes ferrous iron to ferric iron, which is beneficial to the formation of vanadium iron during vanadium precipitation. Simultaneously, scandium co-precipitation enrichment is achieved during vanadium precipitation. The vanadium precipitation solution (i.e., the nickel-cobalt solution purified by removing iron and scandium) undergoes a second oxidation treatment to oxidize ferrous manganese to tetravalent manganese to form manganese dioxide precipitate, which is then separated and recovered. For the third leaching solution after manganese removal, nickel-cobalt extraction is performed using a saponified acidic organic extractant to separate and purify nickel-cobalt, thereby improving the nickel-cobalt extraction efficiency, reducing the difficulty, and achieving the separation of nickel-cobalt from scandium and manganese.

[0031] Furthermore, this invention also enables the recycling of saponification wastewater. During vanadium precipitation and iron removal, ammonium, sodium, and potassium in the saponification wastewater generated during the nickel-cobalt extraction process are recycled. Iron is removed from the leaching solution using the (ammonium, sodium, potassium) alum ore formation method, forming a nickel-cobalt-containing solution with a scandium-doped / adsorbed alum-type precipitate. The scandium-doped / adsorbed alum-type precipitate is mainly potassium ferroalloy, sodium ferroalloy, and ammonium ferroalloy, achieving the removal of iron impurities, scandium enrichment, and the recycling of elements. Attached Figure Description

[0032] Figure 1 This is a schematic flowchart of a method for separating and recovering scandium and nickel-cobalt-manganese in one embodiment of the present invention. Detailed Implementation

[0033] 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.

[0034] As mentioned earlier, scandium separation in nickel-cobalt materials suffers from problems such as low precipitation rate, difficulty in accurately controlling the endpoint pH, and increased loss of nickel, cobalt, and manganese in the slag. High manganese content in the solution also affects nickel-cobalt extraction. This invention proposes a metal separation and recovery method that involves stepwise oxidation of variable-valence metals iron and manganese, coupled with vanadium precipitation for iron removal and co-precipitation enrichment of scandium, and precipitation separation and recovery of manganese. Then, the purified leachate after iron, scandium, and manganese removal is used for nickel-cobalt extraction with a saponified acidic organic extractant. This method improves nickel-cobalt extraction efficiency, reduces extraction difficulty, and achieves the separation of nickel, cobalt, and scandium-manganese.

[0035] The present invention provides a method for separating and recovering scandium from nickel, cobalt, and manganese, which specifically includes the following steps: Step S1: Add sulfuric acid solution to nickel-cobalt material for leaching, and separate solid and liquid to obtain the first leachate; 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. Step S3: Add a salt solution to the first oxidized leachate to precipitate alum and remove iron, and separate the solid and liquid to obtain scandium-containing iron-vanadium slag and a second leachate purified by removing iron and scandium; wherein the salt solution contains one or more of sodium, potassium and ammonia; 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 purified by removing manganese. Step S5: The third leachate is subjected to nickel-cobalt extraction using a saponified acidic organic extractant to separate and purify nickel-cobalt.

[0036] By employing sulfuric acid leaching followed by stepwise oxidation of the leachate, the first oxidation treatment oxidizes ferrous iron to ferric iron, thus facilitating the formation of vanadium and iron during vanadium precipitation. Simultaneously, scandium co-precipitation enrichment is achieved during vanadium precipitation and iron removal. 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 to form manganese dioxide precipitate, which is then separated and recovered. Subsequently, the third leaching solution purified after manganese removal is used for nickel-cobalt extraction with a saponified acidic organic extractant, thereby improving the nickel-cobalt extraction efficiency. This method enables the separation and recovery of nickel, cobalt, scandium, and manganese, offering advantages such as high impurity separation efficiency, high recovery rates of nickel, cobalt, manganese, and scandium, and low equipment investment and operating costs.

[0037] In step S1, to further improve the leaching effect of nickel, cobalt, scandium, iron, and manganese, preferably, the liquid-to-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 controlled to be 15 to 45°C, more preferably 20 to 40°C. The leaching time is preferably 5 to 50 minutes.

[0038] Furthermore, the sulfuric acid solution is preferably a dilute sulfuric acid solution. More specifically, the dilute sulfuric acid solution is preferably prepared using waste dilute sulfuric acid solution from the nickel-cobalt extraction washing section and a sulfuric acid-containing organic phase washing liquid. The concentration of the dilute sulfuric acid solution is preferably 0.1–3 mol / L to achieve the recycling of the sulfuric acid reagent.

[0039] In some preferred embodiments, in order to achieve more efficient stepwise oxidation 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 leachate.

[0040] Further, in step S2, the pH of the first leachate is adjusted to 1.0 to 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 to 4.0; the temperature is 20 to 45°C, such as 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, etc., preferably 30 to 40°C.

[0041] Further, in step S4, the pH of the second leachate is adjusted to 3.0–6.5, such as 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 is 45–95°C, such as 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.

[0042] 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, utilizing the differences in the effects of temperature and solution pH on the oxidation sequence of Fe(II) and Mn(II) ions, efficiently achieves the stepwise oxidation of ferrous iron and manganese in solution. Specifically, ferrous iron is first rapidly oxidized to ferric iron, followed by iron removal through alum precipitation and scandium enrichment. The vanadium-precipitated leachate is then further oxidized to precipitate and recover manganese. The purified leachate, after manganese removal, is then subjected to subsequent nickel-cobalt extraction, which improves the extraction efficiency while reducing the extraction difficulty.

[0043] 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 between 2 and 20 minutes. The reaction time for the second oxidation is preferably controlled between 5 and 30 minutes to further improve the oxidation efficiency.

[0044] In stepwise oxidation, the oxidant introduced can be one or more of SO2, oxygen, and air, which can save costs while achieving stepwise oxidation. More preferably, oxygen or air is used as the first oxidant, and SO2 and oxygen / air are used as the second oxidant to achieve complete oxidation of divalent manganese, further improving oxidation efficiency and simplifying the system. Furthermore, the volume fraction ratio of SO2 to oxygen in the second oxidant is controlled to be 3–20:100 to further improve the manganese oxidation and precipitation efficiency.

[0045] In some preferred embodiments, to improve the efficiency of stepwise oxidation, a suitable catalyst is preferably added in step S2 and / or step S4.

[0046] In step S2, a Cu(II)-containing reagent is preferably added as a catalyst for the first oxidation reaction. To further increase the (iron) oxidation reaction rate, the concentration of Cu(II) ions in the Cu(II)-containing reagent is preferably controlled to be 0.005–0.05 mol / L.

[0047] In step S4, a Fe(III)-containing reagent is preferably added as a catalyst for the second oxidation reaction. To further improve the (manganese) oxidation reaction rate, the concentration of Fe(III) ions in the Fe(III)-containing reagent is preferably 0.001–0.1 mol / L. With the addition of the above catalyst, the stepwise oxidation efficiency of metal ions Fe(II) and Mn(II) is higher.

[0048] In step S3, the goethite method is used, and a salt solution containing sodium, potassium, and ammonia is added to the leachate after the first oxidation to remove vanadium and iron. The first oxidation treatment rapidly oxidizes ferrous iron to ferric iron, which is beneficial for vanadium precipitation and iron removal. Ferric iron ions precipitate and co-precipitate with scandium, forming an iron alum-type precipitate doped with or adsorbing scandium, thereby achieving the separation and recovery of iron and scandium, and obtaining a nickel-cobalt-containing solution purified by removing iron and scandium. Compared with the conventional acid leaching-iron and aluminum removal process, this invention can achieve better iron removal and scandium enrichment effects, and does not require raising the pH value to co-precipitate and generate iron-aluminum scandium hydroxide for scandium removal in the iron and aluminum removal stage.

[0049] During the formation of scandium-doped or adsorbed iron alum-type precipitates, Fe 2+ and Sc 3+ Simultaneous 2Fe 2+ +3H₂O + 0.5O₂ = 2FeOOH + 4H₂ + and Sc 3+ +2H₂O=ScOOH+3H + The reaction, through adsorption on the surface of goethite or co-crystallization, forms α-FeOOH crystal precipitates adsorbed or doped with ScOOH, thereby removing iron while separating scandium from nickel and cobalt. The resulting scandium-rich precipitate has a higher crystal structure, is easier to precipitate, wash, and filter, has a lower scandium loss rate and a higher recovery rate, and a lower nickel and cobalt loss rate (into the precipitate residue). In addition, the precipitates (iron-vanadium scandium precipitate and manganese oxide precipitate) can form at higher acidity, reducing the amount of alkali used for neutralization.

[0050] To further improve the efficiency of vanadium precipitation for iron removal, in step S3, preferably, the pH and temperature of the leachate from the first oxidation process are adjusted during the co-precipitation enrichment of scandium for iron removal. More specifically, the pH of the leachate from the first oxidation process is adjusted to 0.5–3.0, preferably 1.0–1.5. More specifically, 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. In addition, to accelerate iron removal, stirring can be performed during the vanadium precipitation process, with a stirring intensity preferably between 100 and 350 r / min.

[0051] 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.

[0052] In some preferred embodiments, the salt solution in step S3 is the saponification waste liquid generated during the saponification process in step S5. The inventors have noted that when nickel and cobalt are extracted using a saponified extractant, a large amount of salt-containing waste liquid is generated during the extraction process. For example, when using saponified acidic organophosphorus extractants such as P204, P507, and Cyanex 272 for extraction and separation, ammonia, sodium hydroxide, potassium hydroxide, etc., are used in the saponification process. Consequently, the extraction of nickel and cobalt using the saponified extractant generates a large amount of salt-containing waste liquid, such as ammonium sulfate, sodium sulfate, and potassium sulfate.

[0053] During the vanadium precipitation and iron removal process, ammonia, sodium, and potassium ions in the saponification waste liquid are recycled. The iron in the leaching solution is removed using the (ammonium, sodium, and potassium) iron alum ore generation method, forming the doped or adsorbed scandium-type precipitate and the nickel-cobalt-containing solution. This process achieves the removal of iron impurities and the enrichment of scandium, while simultaneously recycling the elements in the saponification waste liquid.

[0054] 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 saponification waste liquid to the total amount of iron and scandium elements in the first oxidation leachate is preferably controlled at 1.1 to 5.5:1.

[0055] In step S5, nickel-cobalt extraction is performed using a saponified acidic organic extractant. Saponification of the extractant further increases the nickel-cobalt extraction efficiency. Preferably, at least two of the following are selected: di(2-ethylhexyl) phosphate (P204), 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (P507), and di(2,4,4-trimethylpentyl)phosphonic acid (Cyanex 272). The inventors have noted that using two or more acidic organophosphorus extractants results in better phase separation and higher extraction recovery compared to using a single extractant system. This is likely due to the different branched structures and functional group electron cloud densities of the extractants, leading to a synergistic extraction effect between extractant molecules during nickel-cobalt extraction. More preferably, each acidic organophosphorus extractant accounts for at least 10% of the total extractant to fully leverage the synergistic extraction effect.

[0056] The extractant can be diluted using any one or more diluents selected from No. 5 solvent oil, No. 260 solvent oil, and sulfonated kerosene. Preferably, the volume concentration of the extractant in the diluted solution is 10–40%.

[0057] The saponifying agent used in the extractant saponification is an alkaline solution containing one or more of sodium, potassium, and ammonium ions. Preferably, the saponifying agent is any one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, and ammonium carbonate. Further, the saponification rate is preferably 10-60%.

[0058] In some embodiments, to further separate and purify nickel and cobalt, a multi-stage countercurrent extraction, washing, and back-extraction process is employed for nickel and cobalt extraction. Specifically, this includes: multi-stage countercurrent extraction; 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 extracted organic phase.

[0059] To further improve the efficiency of nickel-cobalt separation and purification, the process parameters for each stage were optimized. Specifically, in the extraction stage: the preferred number of extraction stages is 3–6; the preferred extraction temperature for each stage is 20–60℃; and the preferred extraction time for each stage is 3–6 min. In the washing stage: the preferred number of washing stages is 2–5; the preferred washing solution for the extracted organic phase is a dilute sulfuric acid solution, with a concentration of 1%–10%. 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.

[0060] 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: 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. 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. Step S31: Add saponification waste liquid containing ammonia, sodium and potassium sulfate to the first oxidized leachate for precipitation and iron removal, so as to remove scandium from the first leachate using the iron alum ore method. While forming an iron alum-type precipitate with adsorption or doping of scandium, scandium is enriched. The alum precipitate slurry is subjected to a second solid-liquid separation to obtain scandium-containing iron-vanadium slag (processed to obtain scandium product) and a second leachate purified by iron and scandium removal (a solution containing nickel and cobalt). 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). Step S51: The leachate is subjected to nickel-cobalt extraction using saponified acidic organic extractants (at least two types) to separate and purify nickel-cobalt, and to generate saponified waste liquid containing ammonia, sodium, and potassium sulfate.

[0061] This method addresses the issue of nickel-cobalt hydroxide produced from laterite nickel ore. After sulfuric acid leaching, an oxidant is introduced under low pH conditions to oxidize the sulfuric acid leaching solution (containing variable-valence metal ions), rapidly oxidizing ferrous iron to ferric iron (Fe3+) to facilitate the subsequent formation of ferrous sulfate. The ferrous sulfate process is employed, and the saponification wastewater containing ammonia, sodium, and potassium sulfates is recycled. This facilitates the precipitation of vanadium, removal of iron, and co-precipitation enrichment of scandium, achieving the removal and recovery of both iron and scandium. The post-ferrous sulfate solution is further oxidized by introducing an oxidant to rapidly oxidize ferrous manganese to ferric manganese, forming manganese dioxide precipitate for manganese separation and recovery. The purified leaching solution, after manganese removal, is then subjected to nickel-cobalt extraction, thereby improving the extraction efficiency. The use of saponified extractants, employing at least two acidic organic extractants, significantly enhances the extraction and separation efficiency of nickel and cobalt. This comprehensive method achieves efficient separation, enrichment, and recovery of nickel, cobalt, manganese, and scandium metal elements.

[0062] The invention and its effects are further illustrated below with reference to specific embodiments.

[0063] 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%.

[0064] Example 1 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.

[0065] 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.

[0066] 3) Add sulfuric acid to the oxidized leachate to control the pH value of the oxidized leachate at 1.5, control the temperature of the leachate at 40℃, control the stirring intensity at 300 r / min, add saponification waste liquid containing sodium ions to precipitate alum and remove iron and scandium, and make the molar ratio of the added sodium to the total amount of iron and scandium metal elements in the leachate 3.2:1, the precipitation time is 50 min, and filter to obtain scandium-rich iron-vanadium second leachate. The scandium enrichment and recovery rate reached 95.9%.

[0067] 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%.

[0068] 5) The organophosphate extractants Cyanex272 and P204 were diluted with solvent oil No. 5. The molar ratio of Cyanex272 to P204 was 2:1, and the volume concentration of the extractant was 30%. The diluted extractant solution was subjected to saponification treatment. The saponifying agent was 2 mol / L sodium hydroxide. The saponification rate of Cyanex272 was 50%. Saponification yielded a saponified organic phase and a saponification waste liquid containing sodium ions.

[0069] 6) The saponified organic phase described above was used to extract and separate nickel and cobalt in the third leaching solution; wherein, the extraction stage was a 4-stage countercurrent extraction at a temperature of 20℃ for 4 min; the washing stage was a 4-stage washing stage, the washing solution for the organic phase loaded with extraction was a 1% dilute sulfuric acid solution at a temperature of 30℃; the washed organic phase loaded with extraction was subjected to a 6-stage back-extraction with a 1 mol / L sulfuric acid solution at a temperature of 40℃.

[0070] Tests showed that the total recovery rate of extraction-washing-back-extraction was 97.6% for nickel and 98.0% for cobalt.

[0071] Example 2 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.

[0072] 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.

[0073] 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 ammonium ions to precipitate alum and remove iron and scandium, so that the molar ratio of the added ammonium ions to the total amount of iron and scandium metal elements in the leachate 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%.

[0074] 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%.

[0075] 5) Prepare a 260# solvent oil solution containing 25% organophosphate extractants P507 and P204, wherein the molar ratio of P507 to P204 is 1:1; saponify the above extractant solution, wherein the saponifying agent is 3.5 mol / L ammonia water, the saponification rate is 40%, and the saponification yields a saponified organic phase and a saponified waste liquid containing ammonium ions.

[0076] 6) The above-mentioned saponified organic phase is used to extract and separate nickel and cobalt in the third leaching solution; wherein, the extraction is carried out by 6-stage countercurrent extraction at a temperature of 40℃; the washing stage has 4 stages, and the washing solution of the organic phase loaded with extraction is a 2% dilute sulfuric acid solution; the washed organic phase loaded with extraction is subjected to 4-stage back-extraction with 2mol / L sulfuric acid solution.

[0077] Testing revealed that the total recovery rates of extraction-washing-back-extraction were 97.5% for nickel and 98.1% for cobalt.

[0078] Example 3 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.

[0079] 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.

[0080] 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 containing ammonium ions to precipitate alum and remove iron and scandium, so that the molar ratio of the added ammonium ions to the total amount of iron and scandium metal elements in the leachate 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%.

[0081] 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%.

[0082] 5) Prepare a sulfonated kerosene solution containing 40% organic phosphoric acid extractant Cyanex272 and organic phosphoric acid extractant P507, with a molar ratio of organic phosphoric acid extractant Cyanex272 to organic phosphoric acid extractant P507 of 1:1; use the above extractant solution as a saponifying agent with 4 mol / L ammonium carbonate solution, with a saponification rate of 40%, and obtain a saponified organic phase and a saponified waste liquid containing ammonium ions.

[0083] 6) The above-mentioned saponified organic phase was used to extract and separate nickel and cobalt in the third leaching solution. The extraction was carried out by 6-stage countercurrent extraction at a temperature of 40℃. The washing stage consisted of 5 stages. The washing solution for the organic phase loaded with extraction was a 5% dilute sulfuric acid solution. The washed organic phase loaded with extraction was then subjected to 6-stage back-extraction with a 5 mol / L sulfuric acid solution.

[0084] Tests showed that the total recovery rate of extraction-washing-back-extraction was 98.3% for nickel and 98.0% for cobalt.

[0085] Example 4 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.

[0086] 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.

[0087] 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%.

[0088] 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%.

[0089] 5) Prepare a sulfonated kerosene solution containing 40% organophosphoric acid extractants P204, P507, and Cyanex272, with a molar ratio of organophosphoric acid extractant P204: P507: Cyanex272 of 0.5: 0.5: 1; use the above extractant solution as a saponifying agent with a 2 mol / L potassium carbonate solution, achieving a saponification rate of 20%, and obtain a saponified organic phase and a saponified waste liquid containing potassium ions.

[0090] 6) The above-mentioned saponified organic phase was used to extract and separate nickel and cobalt in the third leaching solution. The extraction was carried out by four-stage countercurrent extraction at a temperature of 40°C. The washing stage consisted of four stages, and the washing solution for the organic phase loaded with extraction was a 2% dilute sulfuric acid solution. The washed organic phase loaded with extraction was then subjected to six-stage back-extraction with a 3 mol / L sulfuric acid solution.

[0091] Testing showed that the total recovery rate of extraction-washing-back-extraction was 98.0% for nickel and 98.2% for cobalt.

[0092] Example 5 The difference from Example 1 is that, In step S5), the organophosphate extractant Cyanex272 is diluted with diluent 5# solvent oil to a volume concentration of 30%. The diluted extractant solution is then subjected to saponification treatment, wherein the saponifying agent is 2 mol / L sodium hydroxide and the saponification rate of Cyanex272 is 50%. Saponification yields a saponified organic phase and a saponification waste liquid containing sodium ions.

[0093] Tests showed that the total recovery rate of extraction-washing-back-extraction was 97.1% for nickel and 97.5% for cobalt.

[0094] Comparative Example 1 The difference from Example 1 is that, The method does not include step 4), which involves using a second oxidant to enrich manganese; instead, the same extraction system is used to directly extract and separate nickel and cobalt from the second leachate. The results showed that the presence of manganese affected the nickel-cobalt extraction, ultimately reducing the recovery rate of nickel and cobalt.

[0095] In some embodiments of this invention, a stepwise oxidation coupled with Fe(II) and Mn(II) metal ions is used to remove iron and scandium, separate and enrich manganese, and a saponification extractant is used for nickel-cobalt extraction, achieving comprehensive metal recovery. This method has the following advantages: 1) Leach nickel-cobalt hydroxide with sulfuric acid under normal pressure, adjust the pH and temperature of the sulfuric acid leaching solution, introduce an oxidizing agent, and utilize the generated intermediate products such as SO5. •- 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.

[0096] 2) First, ferrous iron (Fe2+) is rapidly oxidized to ferric iron (Fe3+), then the ferric ions are precipitated as alum and enriched with scandium. The precipitated alum utilizes the saponification wastewater containing ammonia, sodium, and potassium generated during the nickel-cobalt extraction saponification process. Iron is removed from the leaching solution using an (ammonium, sodium, potassium) alum ore formation method, forming scandium-doped or adsorbed alum-type precipitates (mainly jaundice, sodium jaundice, and ammonium jaundice). This yields a nickel-cobalt-containing solution, simultaneously removing iron impurities and enriching scandium. The elements are recycled, and the resulting scandium-rich precipitate has a higher crystal structure, making it easier to precipitate, wash, and filter, resulting in lower scandium loss and higher recovery rates. The loss rate of nickel and cobalt (into the precipitate residue) is also lower. Furthermore, the oxidized manganese and iron-vanadium scandium precipitates can form under higher acidity, reducing the need for alkali neutralization.

[0097] 3) Then, the solution after precipitation of alum, which is the purified nickel-cobalt solution after removing iron and scandium, is oxidized by passing SO2 and oxygen or air through it. This causes the divalent manganese in the solution to be rapidly oxidized to tetravalent manganese, forming manganese dioxide precipitate. After the reaction is completed, liquid-solid separation is performed, and manganese can be removed and recovered by filtration.

[0098] 4) Use acidic organic extractants to extract nickel and cobalt, and use alkaline solutions containing ammonia, sodium, and potassium to saponify the nickel and cobalt extractants. Saponification further increases the efficiency of nickel and cobalt extraction and separation. The solution containing ammonium sulfate, sodium sulfate, or potassium sulfate produced after saponification can be recycled in the vanadium precipitation and iron removal process.

[0099] 5) When two or more acidic organophosphorus extractants are used for extraction, the phase separation effect is better and the extraction recovery rate is higher than that of a single extractant system. The reason may be that the different branched structures and functional group electron cloud densities of the extractants result in a certain synergistic extraction effect between extractant molecules during nickel-cobalt extraction.

[0100] In addition, the organic phase loaded with the extract is washed with a dilute sulfuric acid solution, and the resulting sulfuric acid washing solution can be used to prepare the sulfuric acid for leaching in step 1).

[0101] In summary, the method of the present 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.

[0102] 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 separating and recovering scandium from nickel-cobalt-manganese, characterized by, include: Step S1: Add sulfuric acid solution to nickel-cobalt material for leaching, and separate solid and liquid to obtain the first leachate; 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. Step S3: Add a salt solution to the first oxidized leachate to precipitate alum and remove iron, and separate the solid and liquid to obtain scandium-containing iron-vanadium slag and a second leachate purified by removing iron and scandium; wherein the salt solution contains one or more of sodium, potassium and ammonia; 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 purified by removing manganese. Step S5: The third leachate is subjected to nickel-cobalt extraction using a saponified acidic organic extractant to separate and purify nickel-cobalt.

2. The method for separating and recovering scandium and nickel-cobalt-manganese according to claim 1, characterized in that, Step S2 further includes: adjusting the pH of the first leachate to 1.0-4.5 and the temperature to 20-45°C; Step S4 further includes: adjusting the pH of the second leachate to 3.0-6.5 and the temperature to 45-95°C.

3. The method for separating and recovering scandium and nickel-cobalt-manganese according to claim 1, characterized in that, The first oxidant is oxygen or air; The second oxidant is SO2 and oxygen / air; wherein, in the second oxidant, the volume fraction ratio of SO2 to oxygen is (3~20):

100.

4. The method for separating and recovering scandium and nickel-cobalt-manganese according to any one of claims 1-3, characterized in that, Step S2 also includes: adding a Cu(II)-containing reagent as a catalyst for the first oxidation reaction; Step S4 also includes adding a Fe(III)-containing reagent as a catalyst for the second oxidation reaction.

5. The method for separating and recovering scandium and nickel-cobalt-manganese according to claim 4, characterized in that, In the Cu(II)-containing reagent, the concentration of Cu(II) ions is 0.005–0.05 mol / L; The concentration of Fe(III) ions in the Fe(III)-containing reagent is 0.001–0.1 mol / L.

6. The method for separating and recovering scandium and nickel-cobalt-manganese according to claim 1, characterized in that, The acidic organic extractant is at least two of P204, P507, and Cyanex272; wherein each acidic organophosphorus extractant accounts for no less than 10%.

7. The method for separating and recovering scandium and nickel-cobalt-manganese according to claim 1, characterized in that, In step S5, the saponifying agent used for saponification is one or more of ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and ammonium carbonate; the saponification rate is 10-70%. The saponification waste liquid contains one or more of the following: ammonium sulfate, sodium sulfate, and potassium sulfate solution; the saponification waste liquid is recycled as a salt solution in step S3.

8. The method for separating and recovering scandium and nickel-cobalt-manganese according to claim 1, characterized in that, Step S3 also includes: The pH of the first oxidized leachate was adjusted to 0.5–3.0, the temperature to 40–95°C, and the precipitation time to 40–400 min. The molar ratio of the total amount of alkali metal ions to the total amount of iron and scandium in the solution is controlled to be (1.1 to 5.5):

1.

9. The method for separating and recovering scandium from nickel, cobalt, and manganese according to claim 1, characterized in that, Step S5 includes: performing nickel-cobalt multi-stage countercurrent extraction on the third leachate using a saponified acidic organic extractant; using a dilute sulfuric acid solution as a washing liquid to perform multi-stage washing on the extracted organic phase to generate a sulfuric acid-containing organic phase washing liquid; and performing multi-stage back-extraction on the washed extracted organic phase. The extraction section has 3 to 6 extraction stages, with each stage having an extraction temperature of 20 to 60°C and an extraction time of 3 to 6 minutes. The washing section has 2 to 5 washing stages, with the concentration of the dilute sulfuric acid solution used as the washing liquid being 1 to 10%.

10. The method for separating and recovering scandium from nickel, cobalt, and manganese according to claim 1 or 9, characterized in that, In step S1, 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. The nickel-cobalt-containing material is nickel-cobalt hydroxide produced from laterite nickel ore; The sulfuric acid solution is a dilute sulfuric acid solution, which is prepared using an organic phase washing liquid containing sulfuric acid produced during the washing section of nickel-cobalt extraction.

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