Methods for enrichment and separation of nickel, cobalt, and scandium

Abstract

This invention discloses a method for enriching and separating nickel, cobalt, and scandium, belonging to the field of metal production or refining technology. The method includes: slurrying nickel-cobalt hydroxide with water; oxidizing the slurry by introducing sulfur dioxide and oxygen or air, adding a catalyst, and enhancing the oxidation using ultrasound; leaching the oxidized slurry with dilute sulfuric acid to separate a first leachate and manganese oxide slag; precipitating vanadium and removing iron from the first leachate, and separating the solid and liquid phases to obtain scandium-rich iron alum slag and a second leachate; forming a synergistic extraction system using an organophosphate extractant and a hydroxyoxime extractant and saponifying them; using the saponified organic phase to perform kinetic extraction and separation of nickel and cobalt in the second leachate, wherein cobalt is preferentially extracted to obtain a cobalt-loaded organic phase for separation and purification to obtain the cobalt product; then, nickel extraction is performed on the cobalt extraction residue to obtain a nickel-loaded organic phase for separation and purification to obtain the nickel product. This invention achieves efficient extraction and separation of nickel and cobalt, and realizes scandium enrichment.

Description

Technical Field

[0001] This invention relates to the field of metal production or refining technology, and in particular to a method for enriching and separating nickel, cobalt, and scandium. Background Technology

[0002] Laterite nickel ore has become a major nickel-cobalt resource, also containing associated resources such as scandium and manganese. However, the utilization of laterite nickel ore resources currently faces two major problems: firstly, valuable elements such as scandium and manganese are difficult to recover efficiently and comprehensively; and secondly, the efficiency of nickel-cobalt recovery and separation is low. The hydrometallurgical process for laterite nickel ore consists of acid leaching, impurity removal, and nickel-cobalt precipitation. Nickel-cobalt hydroxide precipitation is a relatively common intermediate product obtained from the hydrometallurgical process of laterite nickel ore. The main purpose of the nickel-cobalt hydroxide refining process 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 impurity elements such as iron, manganese, scandium, calcium, and magnesium. These impurity elements will enter the acid leaching solution along with the nickel and cobalt during the acid leaching reaction of nickel-cobalt hydroxide. A refining and separation process is required to remove these impurities in order to obtain a pure nickel-cobalt product.

[0004] The technical challenges of separating nickel and cobalt lie not only in separating nickel and cobalt from scandium, iron, aluminum, manganese, calcium, magnesium, etc., but also in separating nickel and cobalt elements themselves.

[0005] In their production and R&D practice, the inventors' team discovered that the iron ions in nickel-cobalt hydroxide have both +3 and +2 valence states, with +3 being the predominant valence state, while the manganese ions have both +2 and +4 valence states, with +2 being the predominant valence state. However, the valence state transition process is very slow. In the conventional nickel-cobalt hydroxide refining process, this uncertainty in the composition of raw materials causes great interference to industrial production, resulting in low purity of nickel-cobalt products, low recovery rate, and unstable operation of the production system.

[0006] Iron ions are the main impurities in the separation and utilization of valuable metals. In nickel-cobalt hydroxide leaching solutions, iron ions are present in both divalent and trivalent states. The iron alum process is a commonly used method for iron removal, but 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 that can be used within the suitable pH range for alum precipitation have disadvantages such as slow oxidation rates and high costs.

[0007] Manganese is one of the impurities that are leached together with nickel and cobalt and processed in the subsequent separation process. Moreover, the valence state of manganese ions is unstable, and manganese interferes with the extraction of nickel and cobalt, affecting the purity of the product.

[0008] Furthermore, a significant amount of nickel-cobalt hydroxide produced from laterite nickel ore contains scandium, which is a harmful impurity in nickel-cobalt smelting and also a rare earth resource. Due to the low concentration of scandium in the system, the precipitation method alone is used to remove and recover scandium, resulting in a low precipitation rate and difficulty in sedimentation, thus making it difficult to concentrate.

[0009] Nickel-cobalt solutions are often extracted and separated using acidic organophosphorus extractants such as P204, P507, and Cyanex 272. However, the extraction equilibrium pH requirement is high, and iron, aluminum, manganese, calcium, and magnesium can easily interfere with the extraction. Before nickel-cobalt extraction, iron, aluminum, and manganese need to be removed by precipitation or extraction methods. Nickel-cobalt extraction and separation is difficult and the process is long (P204 extraction - P507 cobalt extraction - Cyanex 272 deep extraction). Moreover, the saponification process uses ammonia, sodium hydroxide, potassium hydroxide, etc. The process of extracting nickel-cobalt with saponification extractants generates a large amount of salt-containing waste liquid and acid-containing waste liquid, which is not recycled, resulting in reagent waste.

[0010] After conventional leaching, the solution contains both Fe and iron ions. 3+ Fe 2+ The method disclosed in Chinese patent application CN103468948A involves adjusting the pH value to 3.0 or higher during further iron and aluminum removal to co-precipitate scandium with iron and aluminum, which then precipitates as hydroxide, thereby achieving the removal and recovery of scandium from the nickel-cobalt solution. However, in practice, it has been found that this process has a problem: during the formation of hydroxide coprecipitates, 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 not easy to control precisely. Too low a pH value can lead to low scandium recovery, while too high a pH value can lead to colloidal precipitation, affecting filtration performance. Moreover, the reaction is carried out at a higher pH value, which increases the loss of nickel, cobalt, and manganese in the slag.

[0011] To leach high-valence manganese from nickel-cobalt hydroxide, patent CN115094229B describes a method of removing iron from the leaching solution using a goethite method after reductive leaching of the nickel-cobalt hydroxide slurry. This results in the formation of a goethite-type precipitate with adsorbed or doped scandium and a nickel-cobalt-containing solution, thus enriching scandium. However, the inventors have discovered that reductive leaching causes manganese to become divalent, resulting in a high manganese content in the nickel-cobalt solution. This affects nickel-cobalt extraction and increases the difficulty of subsequent nickel-cobalt extraction steps.

[0012] In summary, existing technical solutions have two major problems: first, valuable elements such as scandium and manganese are difficult to recover efficiently and comprehensively; second, the recovery and separation efficiency of nickel and cobalt is low. Therefore, this application is submitted. Summary of the Invention

[0013] According to one embodiment of the present invention, the objective is to provide a method for enriching and separating nickel, cobalt, and scandium, so as to comprehensively achieve the enrichment, recovery, and effective separation of nickel, cobalt, manganese, and scandium.

[0014] The above objective can be achieved through the following technical solutions:

[0015] According to one aspect of the present invention, a method for enrichment and separation of nickel, cobalt, and scandium is provided, comprising:

[0016] Step S1: Add water to nickel-cobalt hydroxide to form a slurry, thereby obtaining a slurry solution;

[0017] Step S2: Sulfur dioxide and oxygen or air are introduced into the slurry for oxidation, Fe(III)-containing reagent and Cu(II)-containing reagent are added, and ultrasonic waves are used to enhance the oxidation to obtain an oxidized slurry.

[0018] Step S3: Add dilute sulfuric acid to the oxidizing slurry for selective leaching, and separate the solid and liquid to obtain the first leachate and manganese oxide slag;

[0019] Step S4: The first leaching solution is subjected to vanadium precipitation and iron removal using the iron alum ore method, and the solid-liquid separation yields scandium-rich iron alum slag and a second leaching solution.

[0020] Step S5: An organophosphate extractant and a hydroxyoxime extractant are used to form a synergistic extraction system. The synergistic extraction system is saponified to obtain a saponified organic phase. The saponified organic phase is then used to perform kinetic extraction separation of nickel and cobalt in the second leachate.

[0021] In this process, cobalt is preferentially extracted to obtain a cobalt-supported organic phase, which is then separated and purified to obtain the cobalt product. The cobalt extraction residue is then subjected to nickel extraction to obtain a nickel-supported organic phase, which is then separated and purified to obtain the nickel product.

[0022] Preferably, in step S2, the volume fraction ratio of sulfur dioxide to oxygen is 5-30:100.

[0023] Preferably, in step S2, the pH of the slurry is 2.0-6.5. More preferably, the pH is 4.0-5.5.

[0024] Preferably, in step S2, the Fe(III)-containing reagent is used as a manganese oxidation catalyst, and the concentration of Fe(III) ions is 0.001-0.1 mol / L.

[0025] Preferably, in step S2, the Cu(II)-containing reagent is used as an iron oxidation catalyst, and the concentration of Cu(II) ions is 0.001-0.02 mol / L.

[0026] Preferably, in step S2, the frequency of the ultrasonic wave is 20kHz-200kHz.

[0027] Preferably, in step S2, the oxidation reaction time is 2-20 min and the temperature is 30-80℃. More preferably, the temperature is 50-70℃.

[0028] Preferably, in step S2, the reaction time for enhanced oxidation is 5-10 min, and the temperature is 25-75℃, with a more preferred temperature of 50-70℃.

[0029] Preferably, in step S5, the molar ratio of the organophosphate extractant to the hydroxyoxime extractant is 0.1-10:1. More preferably, it is 0.5-5:1.

[0030] Preferably, in step S5, the organophosphate extractant is one or more of P204, P507, and Cyanex272; the hydroxyoxime extractant is one or more of aliphatic α-hydroxyoxime extractants, more preferably Lix63.

[0031] Preferably, in step S5, the organophosphate extractant and the hydroxyoxime extractant are diluted with an organic solvent, and the volume concentration of the extractant after dilution is 10-40%.

[0032] Preferably, in step S5, the saponifying agent during saponification is any one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, and ammonium carbonate.

[0033] Preferably, in step S5, the saponification rate is 30-75%.

[0034] Preferably, cobalt is extracted first to obtain a cobalt-supported organic phase, the cobalt-supported organic phase is washed, and then the washed nickel-supported organic phase is back-extracted to obtain the cobalt product.

[0035] Preferably, multi-stage countercurrent extraction of cobalt is adopted, with 2-5 extraction stages, a flow ratio of saponified organic phase to aqueous phase of 0.05-1:1, an extraction temperature of 20-50℃ for each stage, an extraction time of 5-120 seconds for each stage, and an equilibrium pH of 1.0-3.5 for the aqueous phase of extraction.

[0036] Preferably, the cobalt washing section has 2-4 washing stages, and the washing solution is a dilute sulfuric acid solution with a concentration of 0.02-0.8 mol / L.

[0037] Preferably, the cobalt back-extraction stage has 3-6 back-extraction stages and uses sulfuric acid back-extraction solution with a concentration of 1-3 mol / L.

[0038] Preferably, the cobalt extraction residue is further subjected to nickel extraction to obtain a nickel-loaded organic phase, the nickel-loaded organic phase is washed, and the washed nickel-loaded organic phase is then back-extracted to obtain the nickel product.

[0039] Preferably, multi-stage countercurrent extraction of nickel is adopted, with the following extraction stages: 5-10 extraction stages, a flow ratio of saponified organic phase to aqueous phase of 1-10:1, an extraction temperature of 30-60℃ for each stage, an extraction time of 3-10 minutes for each stage, and an equilibrium pH of 2.0-4.5 for the aqueous phase of extraction.

[0040] Preferably, the nickel washing section has 2-4 washing stages, and the washing solution is a dilute sulfuric acid solution with a concentration of 0.02-0.8 mol / L.

[0041] Preferably, the nickel back-extraction section has 3-8 back-extraction stages and uses sulfuric acid back-extraction solution with a concentration of 0.8-2.5 mol / L.

[0042] Preferably, the method further includes: collecting the sulfuric acid waste liquid generated in the nickel and cobalt washing section in step S5 and recycling it to the preparation of the dilute sulfuric acid solution in step S3.

[0043] Preferably, the method further includes: collecting the saponification waste liquid generated during saponification in step S5 and recycling it to step S4, so as to use the iron alum ore method to precipitate vanadium and remove iron from the first leaching solution.

[0044] Preferably, step S1 includes: adding water and mechanically stirring to form a coarse slurry; and using a colloid mill to finely grind the coarse slurry into a refined slurry.

[0045] Preferably, the particle size of the solid particles in the refined slurry is 0.01-10 micrometers;

[0046] Preferably, in step S1, the amount of water added is determined based on the mass ratio of (dry basis) nickel cobalt hydroxide to water of 1:2-10.

[0047] Preferably, in step S3, the concentration of the dilute sulfuric acid is 0.5-3.5 mol / L.

[0048] Preferably, in step S3, during selective leaching, the liquid-to-solid ratio of the leaching system is 20:1-1:1; the pH value of the leaching system is 0.5-2.5; and the leaching temperature is 25-55℃.

[0049] Preferably, in step S3, during selective leaching, the leaching time is 10-30 minutes.

[0050] Preferably, step S4 further includes: adjusting the pH of the first leachate to 0.6-3.5 by adding an alkaline neutralizing agent or sulfuric acid to the first leachate.

[0051] Preferably, the alkaline neutralizing agent is any one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, and ammonium carbonate.

[0052] Preferably, in step S4, when vanadium precipitation is carried out to remove iron, the molar ratio of the total amount of ammonium, sodium, and potassium in the reaction system to the total amount of iron and scandium in the leachate is 1.2-4.5:1; and the temperature of the reaction system is 20-90℃.

[0053] Preferably, in step S4, the reaction time for vanadium precipitation and iron removal is 20-200 min.

[0054] Beneficial effects: The method for enrichment and separation of nickel, cobalt, and scandium provided by one embodiment of the present invention...

[0055] The process involves slurrying nickel-cobalt hydroxide with water, followed by oxidation with sulfur dioxide and oxygen or air. SO2 is then oxidized with oxygen or air, resulting in a gas-liquid-solid reaction. The intermediate products, such as SO5, are utilized. - The strong oxidizing effect of free radical species, the addition of Fe(III) and Cu(II) catalysts and the use of ultrasound to enhance oxidation, increase the reactive area, enhance the reaction activity, and accelerate the reaction rate, so that ferrous iron is rapidly oxidized to ferric iron and ferrous manganese is rapidly oxidized to tetravalent manganese, forming manganese dioxide that is insoluble in weak acid solution, and then separated by leaching with dilute sulfuric acid to obtain manganese oxide slag.

[0056] By using the (ammonium, sodium, potassium) alum ore formation method to remove iron from the leaching solution, i.e. the first leaching solution, scandium is enriched in the alum, and the solid-liquid separation yields scandium-rich alum slag.

[0057] By employing an organophosphate extractant and a hydroxyoxime extractant to form a synergistic extraction system and then saponifying them, the second leaching solution (the leachate after vanadium precipitation and scandium removal) is used for the kinetic extraction and separation of nickel and cobalt. Specifically, cobalt is preferentially extracted to obtain a cobalt-loaded organic phase, and then nickel is extracted from the cobalt extraction residue to obtain a nickel-loaded organic phase. This achieves efficient kinetic extraction and separation of nickel and cobalt at low pH. Furthermore, the extraction of both nickel and cobalt in this synergistic extraction system is direct extraction, meaning that both nickel and cobalt are directly extracted into the organic phase. After purification, cobalt and nickel products can be obtained.

[0058] In summary, this invention can comprehensively achieve the enrichment, recovery, and effective separation of nickel, cobalt, manganese, and scandium.

[0059] Compared with the prior art, the present invention has the following advantages:

[0060] (1) Utilizing the strong oxidizing effect of free radical species generated by SO2 and oxygen, oxidation is carried out in a gas-liquid-solid three-phase system to enhance and accelerate the oxidation rate of variable valence metals, forming insoluble manganese dioxide in a weak acid solution. Manganese oxide slag can be separated and enriched in the subsequent leaching step, thereby achieving the enrichment and separation of manganese through a low-cost means. The leaching solution after manganese separation is more conducive to the subsequent nickel-cobalt extraction. At the same time, the enhanced oxidation forms iron oxide to prepare for the subsequent precipitation and iron removal.

[0061] (2) A novel nickel-cobalt synergistic extraction system is constructed using organophosphate extractant and hydroxyoxime extractant. This system fully utilizes the difference in their kinetic extraction rates for nickel and cobalt (the extraction rate for cobalt is greater than that for nickel) to achieve kinetic extraction and efficient separation of nickel and cobalt, resulting in high purity nickel and cobalt. Saponification increases the extraction and separation efficiency of nickel and cobalt, achieving efficient extraction, separation, and purification of nickel and cobalt at low pH. Moreover, the extraction system and the extraction-impurity system are substantially different from existing conventional acidic extractants. The synergistic extraction system of this invention performs direct extraction of nickel and cobalt, that is, nickel and cobalt are directly extracted into the organic phase. After washing and back-extraction, nickel sulfate is in the back-extraction solution, while nickel in conventional acidic extractants is in the raffinate.

[0062] (3) Nickel-cobalt extraction, oxidation precipitation of manganese and iron-vanadium precipitation can be formed at higher acidity, reducing the need for alkali in neutralization.

[0063] (4) Using the (ammonium, sodium, potassium) iron alum ore generation method to remove iron from the leaching solution, forming an iron alum-type precipitate doped with or adsorbed with scandium, while removing iron impurities, scandium co-precipitation enrichment is achieved, resulting in scandium-rich iron alum slag. The resulting scandium-rich precipitate has a higher crystal form, is easier to precipitate, wash and filter, has a higher scandium recovery rate, and a lower loss rate of nickel and cobalt (into precipitate slag rate). Moreover, the precipitate can be formed at a higher acidity, reducing the use of alkali for neutralization. The nickel-cobalt-containing solution after separating the scandium-rich iron vanadium precipitate is more conducive to subsequent nickel-cobalt extraction.

[0064] In addition, the saponification waste liquid can be recycled during the vanadium precipitation and iron removal process. After saponification, a solution containing ammonium sulfate, sodium sulfate or potassium sulfate will be produced. By using this saponification waste liquid to remove iron and enrich scandium, the ammonium, sodium and potassium elements in the saponification waste liquid are recycled.

[0065] In addition, the pH of the vanadium-precipitated liquid (i.e., the second leachate) is adjusted before nickel-cobalt extraction, which is more conducive to the next step of nickel-cobalt extraction.

[0066] (5) Under normal pressure, nickel-cobalt hydroxide is leached with dilute sulfuric acid solution to dissolve nickel-cobalt hydroxide and leach scandium and nickel-cobalt. At the same time, manganese dioxide is not dissolved and enters the slag to be recovered as manganese oxide slag, thereby achieving the separation of manganese from other metals that enter the leaching solution.

[0067] Moreover, the leaching step can also recycle the sulfuric acid waste generated during the extraction process. During the extraction process, dilute sulfuric acid solution is used to wash the organic phase loaded for extraction. The sulfuric acid waste liquid generated after washing can be used to prepare leaching acid, thereby realizing the recycling of reagents, reducing raw material consumption, and saving costs. Attached Figure Description

[0068] Figure 1 This is a process flow diagram of a method for enriching and separating nickel, cobalt, and scandium in one embodiment of the present invention. Detailed Implementation

[0069] 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.

[0070] Addressing the industry challenges in refining nickel-cobalt hydroxide, namely the presence of other elements such as scandium, manganese, iron, aluminum, calcium, and magnesium, the coexistence of low- and high-valence manganese and iron ions affecting the extraction and separation efficiency of nickel-cobalt, and the inability to comprehensively recover valuable elements such as scandium and manganese, as well as the slow valence state transition process discovered by the inventors' team in production and R&D practice, which causes significant interference to industrial production and instability in the production system, this invention employs a step-by-step separation method (variable valence metal ion oxidation enrichment separation of manganese-iron-vanadium method coupled with scandium enrichment-nickel-cobalt kinetic extraction separation and purification), including: slurrying nickel-cobalt hydroxide with water to obtain a slurry; and introducing sulfur dioxide and oxygen or air into the slurry for further processing. Oxidation is performed with Fe(III)-containing and Cu(II)-containing reagents as catalysts, and the oxidation is enhanced by ultrasound to obtain an oxidized slurry. Dilute sulfuric acid is added to the oxidized slurry for selective leaching, and solid-liquid separation yields a first leachate and manganese oxide slag. The first leachate is then treated with a method involving the precipitation of vanadium and removal of iron using an iron alum ore, and solid-liquid separation yields scandium-rich iron alum slag and a second leachate. A synergistic extraction system is formed using an organophosphate extractant and a hydroxyoxime extractant, followed by saponification. The saponified organic phase is then used for kinetic extraction and separation of nickel and cobalt in the second leachate, preferentially extracting cobalt to obtain a cobalt-loaded organic phase for further purification to obtain the cobalt product. The cobalt extraction residue is then subjected to nickel extraction to obtain a nickel-loaded organic phase for further purification to obtain the nickel product. This invention achieves efficient separation and recovery of elements such as nickel, cobalt, scandium, and manganese, yielding high-purity nickel and cobalt products, while simultaneously enriching and recovering scandium and manganese.

[0071] The reaction principles and effects of each step in this invention are explained below:

[0072] First, nickel-cobalt hydroxide is treated with water to form a slurry, which is beneficial for subsequent oxidation and leaching steps. An enhanced slurry pretreatment is used, in which the crude slurry is first mechanically stirred to form a crude slurry, and then a colloid mill is used to finely grind the crude slurry into a refined slurry with finer and more dispersed solid particles, which is more conducive to subsequent oxidation and leaching.

[0073] Secondly, SO2 and oxygen or air are introduced into the slurry to oxidize it, causing a gas-liquid-solid reaction, and the intermediate products such as SO5 are utilized. - The strong oxidizing effect of free radical species rapidly oxidizes divalent manganese to tetravalent manganese to form manganese dioxide and divalent iron to trivalent iron to form ferric hydroxide. Furthermore, the addition of catalysts containing Fe(III) and Cu(II), along with the application of a microwave field and the ultrasonic cavitation effect (which generates a large number of active free radicals, enhances intermolecular collisions, and increases the chemical reaction rate), accelerates the gas / liquid / solid interface reaction kinetics. This results in enhanced surface reactivity, making the reaction easier and allowing for faster oxidation of divalent manganese to tetravalent manganese to form manganese dioxide and divalent iron to trivalent iron to form ferric hydroxide.

[0074] Next, the pretreated nickel-cobalt hydroxide was selectively leached with sulfuric acid under normal pressure to dissolve the nickel-cobalt hydroxide and leach scandium and nickel-cobalt. The pH and temperature of the sulfuric acid leaching solution of nickel-cobalt hydroxide were adjusted so that the generated manganese dioxide did not dissolve while other metals dissolved, resulting in liquid-solid separation. Manganese entered the slag to form manganese oxide slag, while other metals entered the leaching solution, thereby achieving manganese recovery and obtaining a purified second leaching solution after manganese removal.

[0075] Furthermore, scandium enrichment was achieved by precipitating ferric ions and co-precipitating trace amounts of scandium ions. By utilizing the ammonium, sodium, and potassium-containing wastewater generated during the saponification process using nickel-cobalt extractants, the leaching solution was treated with an ammonium, sodium, and potassium (AM) alum ore production method to remove iron, forming scandium-doped or adsorbed alum-type precipitates (mainly jaundice, sodium jaundice, and ammonium jaundice) and a nickel-cobalt-containing solution. This simultaneously removed iron impurities and enriched scandium, allowing for the recycling of ammonium, sodium, and potassium elements in the saponification wastewater. Moreover, the resulting precipitates had higher crystal structures, making them easier to precipitate, wash, and filter. Using the vanadium ore production method to achieve iron removal and scandium co-precipitation, the vanadium-iron scandium precipitate could form at higher acidity, eliminating the need for co-precipitation of iron-aluminum scandium hydroxide during the iron-aluminum removal stage, thus reducing the use of alkali for neutralization.

[0076] Finally, combining phosphoric acid extractant and hydroxime extractant into a synergistic extraction system for nickel-cobalt extraction and separation significantly improves the efficiency of nickel-cobalt extraction and separation. On one hand, by fully utilizing the difference in kinetic extraction rates between nickel and cobalt, efficient separation of nickel and cobalt is achieved. This synergistic extraction system extracts cobalt faster, preferentially extracting it and thus achieving kinetic extraction separation of cobalt. Furthermore, cobalt is directly extracted into the organic phase (high-purity cobalt product can be obtained by sequentially washing and back-extracting the cobalt-loaded organic phase). Then, nickel is extracted from the raffinate after cobalt extraction, and similarly, nickel is directly extracted into the organic phase (high-purity nickel product can be obtained by sequentially washing and back-extracting the nickel-loaded organic phase). On the other hand, because the phosphoric acid extractant and hydroxime extractant form more hydrophobic and spatially stable complexes (metal ion-extractant complexes) with nickel and cobalt ions, the extraction efficiency of nickel and cobalt is enhanced. Therefore, efficient extraction of nickel and cobalt and effective separation from impurities such as iron, aluminum, calcium, and magnesium can be achieved at lower pH levels, eliminating the need for precipitation to remove impurities such as iron and aluminum from the original extraction solution and further reducing the amount of alkali used for neutralization. On the other hand, using ammonium, sodium, and potassium alkaline solutions to saponify the synergistic extraction system can further increase the efficiency of nickel-cobalt extraction and separation.

[0077] In summary, manganese separation, enrichment, and recovery are achieved by oxidizing the slurry to oxidize variable-valence metal ions Fe(II) and Mn(II) and coupling it with selective leaching. The iron-vanadium method simultaneously removes iron and enriches scandium. A newly constructed synergistic extraction system achieves kinetic separation of cobalt and purification of nickel, efficiently extracting nickel and cobalt. This results in the efficient comprehensive recovery of metal elements such as nickel, cobalt, scandium, and manganese, offering advantages such as higher recovery rates for nickel, cobalt, scandium, and manganese, and higher separation efficiency from impurities. Furthermore, the use of saponification wastewater for iron and scandium removal enables the recycling of ammonium, sodium, and potassium elements. The preparation of dilute sulfuric acid for leaching using the washed sulfuric acid wastewater achieves the recycling of acid reagents. In conclusion, the proposed method offers advantages such as high impurity separation efficiency, high recovery rates of nickel, cobalt, manganese, and scandium, low raw material consumption, and element recycling.

[0078] One embodiment of the present invention provides a method for enrichment and separation of nickel-cobalt-scandium, with reference to... Figure 1 As shown, it includes:

[0079] Step S1: Add water to nickel-cobalt hydroxide to form a slurry, thus obtaining a slurry solution.

[0080] Preferably, the amount of water added is determined based on a (dry basis) nickel-cobalt hydroxide:water mass ratio of 1:2-10.

[0081] Furthermore, a slurry-grinding process can be employed to further enhance the particle size distribution. First, water is added and mechanically stirred to form a coarse slurry. Then, a colloid mill is used to finely grind the coarse slurry into solid particles, resulting in a finer and more dispersed refined slurry. The particle size of the colloid mill output can be 0.01-10 micrometers.

[0082] Step S2: Sulfur dioxide and oxygen or air are introduced into the slurry for oxidation, and Fe(III)-containing reagent and Cu(II)-containing reagent are added as catalysts. Ultrasonic waves are used to enhance the oxidation, so that low-valence manganese is oxidized to tetravalent manganese to form manganese dioxide more quickly, and divalent iron is oxidized to trivalent iron ions more quickly, resulting in an oxidized slurry with increased valence of iron and manganese metals.

[0083] In this step, sulfur dioxide and oxygen or air can be introduced, and after adding a catalyst, the oxidation can be directly enhanced by ultrasound. Alternatively, sulfur dioxide and oxygen or air can be introduced first, and the reaction can be carried out at a temperature of 30-80℃, preferably 50-70℃, for 2-20 minutes; then, a catalyst can be added, and the oxidation can be enhanced by ultrasound at a temperature of 25-75℃, preferably 50-70℃, for 5-10 minutes.

[0084] Oxidation occurs by introducing SO2 and oxygen / air, resulting in a gas-liquid-solid reaction. The intermediate products, such as SO5, are utilized. The strong oxidizing effect of free radical species rapidly oxidizes divalent manganese to tetravalent manganese to form manganese dioxide, and rapidly oxidizes divalent iron to trivalent iron to form ferric hydroxide. Furthermore, the volume fraction ratio of introduced SO2 to oxygen is 5-30:100. The solution pH is 2.0-6.5, preferably 4.0-5.5.

[0085] A Fe(III)-containing reagent is added as a catalyst for the manganese oxidation reaction to accelerate the reaction rate. Further, the concentration of Fe(III) ions in the Fe(III)-containing reagent is preferably 0.001-0.1 mol / L, for example, 0.001 mol / L, 0.005 mol / L, 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, etc. Examples of Fe(III)-containing reagents include ferric sulfate solution.

[0086] A Cu(II)-containing reagent is added as a catalyst for the iron oxidation reaction to accelerate the Fe(II) oxidation rate. Further, the concentration of Cu(II) ions in the Cu(II)-containing reagent is preferably 0.001-0.02 mol / L, for example, 0.001 mol / L, 0.005 mol / L, 0.01 mol / L, 0.015 mol / L, 0.02 mol / L, etc. The Cu(II)-containing reagent is, for example, a copper sulfate solution.

[0087] The ultrasonic cavitation effect of ultrasound can generate a large number of active free radicals, enhancing intermolecular collisions, increasing chemical reaction rates, accelerating gas / liquid / solid interface reaction kinetics, and enhancing the reactivity of solid surfaces. Furthermore, the preferred frequency of the ultrasound is 20 kHz to 200 kHz (20 kHz to 200 kHz), such as 20 kHz, 50 kHz, 100 kHz, 150 kHz, and 200 kHz.

[0088] Step S3: Add dilute sulfuric acid solution to the oxidizing slurry for selective leaching to leach nickel, cobalt, and scandium, while manganese is enriched in the slag. Perform a first solid-liquid separation on the leaching system to obtain manganese oxide slag and a first leaching solution purified by removing manganese.

[0089] To more efficiently leach nickel, cobalt, and scandium and separate them from manganese, the concentration of the dilute sulfuric acid solution used for leaching is preferably 0.5-3.5 mol / L. Preferably, the liquid-to-solid ratio of the leaching system is 20:1-1:1. Preferably, the pH value of the leaching system is 0.5-2.5, more preferably 1.0-2.0. Preferably, the leaching temperature is 25-55°C, more preferably 30-40°C, and the leaching time is preferably 10-30 min. Further processing of the manganese oxide slag yields manganese products.

[0090] In addition, the dilute sulfuric acid solution used for leaching can also be prepared by mixing the sulfuric acid-containing organic phase washing liquid (i.e., dilute sulfuric acid waste solution) generated in the nickel-cobalt extraction and washing section of step S5 with water and concentrated sulfuric acid, so as to realize the recycling of acid reagents and reduce raw material consumption.

[0091] Step S4 involves adding a sulfate solution containing one or more of ammonium, sodium, and potassium to the first leachate to precipitate vanadium and remove scandium using the iron alum ore method, forming an iron alum-type precipitate with adsorbed or doped scandium. The precipitate slurry is then subjected to a second solid-liquid separation to obtain scandium-enriched iron-vanadium slag (i.e., scandium-rich iron alum slag) and a purified solution containing nickel and cobalt after removing scandium (i.e., the second leachate).

[0092] To more efficiently remove iron and co-precipitate scandium by alum precipitation, the pH of the first leachate is first adjusted. This is achieved by adding an alkaline neutralizing agent or sulfuric acid to the first leachate, controlling the pH value between 0.6 and 3.5, preferably between 0.8 and 1.8. The alkaline neutralizing agent is any one or more alkaline solutions such as sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, and ammonium carbonate.

[0093] To achieve scandium enrichment through vanadium precipitation and iron removal more efficiently, the molar ratio of the total amount of ammonium, sodium, and potassium in the reaction system to the total amount of iron and scandium in the leachate is preferably controlled at 1.2-4.5:1. Preferably, the temperature of the leachate is controlled at 20-90℃, more preferably 40-70℃. Preferably, the precipitation time is 20-200 min. Stirring can be performed during the reaction, with a preferred stirring intensity of 200-500 r / min. The scandium-rich iron vanadium slag is further processed to obtain scandium products.

[0094] In addition, the sulfate solution containing one or more of ammonium, sodium, and potassium can be the saponification waste liquid produced in the saponification process of the co-extractant in step S5, so as to recycle the ammonium, sodium, and potassium elements in the saponification waste liquid.

[0095] Step S5: An organophosphate extractant and a hydroxyoxime extractant are used to form a synergistic extraction system. The synergistic extraction system is saponified to obtain a saponified organic phase. The saponified organic phase is used to perform nickel and cobalt kinetic extraction separation on the second leachate. Cobalt is preferentially extracted to obtain a cobalt-loaded organic phase. The cobalt raffinate containing nickel, calcium, and magnesium is subjected to nickel extraction to obtain a nickel-loaded organic phase.

[0096] The synergistic extractant of this invention performs direct extraction on both nickel and cobalt. That is, after nickel / cobalt extraction using this synergistic extractant, both nickel and cobalt are directly extracted into the organic phase. Then, by washing and back-extracting the nickel / cobalt-loaded organic phase in sequence, the nickel / cobalt products can be separated and purified.

[0097] The synergistic extraction system is formed by compounding an organophosphate extractant, a hydroxyoxime extractant, and an organic diluent in a certain proportion. The organophosphate extractant is one or more selected from 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (P204), 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (P507), and bis(2,4,4-trimethylpentyl)phosphonic acid (Cyanex272). The hydroxyoxime extractant is one or more selected from α-hydroxyoxime extractants containing long-chain alkyl groups (aliphatic α-hydroxyoximes); more preferably, the hydroxyoxime extractant is 5,8-diethyl-7-hydroxy-dodecane-6-oxime (Lix63). The organic diluent is a long-chain alkane, selected from any one or more selected from n-heptane, n-octane, No. 5 solvent oil, No. 260 solvent oil, and sulfonated kerosene. Furthermore, the molar ratio of the organophosphate extractant to the hydroxyoxime extractant is preferably 0.1-10:1, more preferably 0.5-5:1. After dilution with an organic diluent, the volume concentration of the extractant is preferably 10-40%.

[0098] During saponification, a saponifying agent is added to the synergistic extraction system. The saponifying agent is any one or more alkaline solutions such as sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, and ammonium carbonate. After saponification, a saponified organic phase is obtained for nickel-cobalt kinetic extraction and separation, generating saponification waste liquid containing ammonium, sodium, and potassium sulfates. This waste liquid can be recycled to the iron-vanadium ore method for iron removal and scandium enrichment in step S4. Further, the saponification rate is 30-75%, preferably 35-50%. Saponification of the synergistic extraction system further increases the efficiency of nickel-cobalt extraction and separation.

[0099] Cobalt extraction and separation is performed using multi-stage countercurrent extraction with a centrifugal extractor. The cobalt extraction stage involves 2-5 stages of preferential cobalt extraction, with a flow ratio of saponified organic phase to aqueous phase of 0.05-1:1. The extraction temperature for each stage is 20-50℃, and the extraction time for each stage is 5-120 seconds. The equilibrium pH of the aqueous phase is 1.0-3.5, yielding a cobalt-loaded organic phase and a raffinate containing nickel, calcium, and magnesium. After extraction with the synergistic extractant, cobalt is directly extracted into the organic phase. The cobalt-loaded organic phase is then washed, followed by back-extraction of the washed nickel-loaded organic phase to obtain a cobalt sulfate solution, ultimately yielding the cobalt product. The washing stage involves 2-4 stages of washing, using a dilute sulfuric acid solution with a concentration of 0.02-0.8 mol / L, generating a waste dilute sulfuric acid solution. The back-extraction stage involves 3-6 stages of back-extraction, using a sulfuric acid back-extraction solution with a concentration of 1-3 mol / L.

[0100] Nickel extraction and separation is performed using multi-stage countercurrent extraction in a mixed-clarification extraction tank. The nickel extraction stage comprises 5-10 stages, with a flow ratio of saponified organic phase to aqueous phase of 1-10:1. Each extraction stage is conducted at 30-60℃ for 3-10 minutes, and the equilibrium pH of the aqueous phase is 2.0-4.5. After extraction with the synergistic extractant, nickel is directly extracted into the organic phase. The nickel-loaded organic phase is then washed, followed by back-extraction to obtain a nickel sulfate solution, ultimately yielding the nickel product. The washing stage comprises 2-4 stages using a dilute sulfuric acid solution at a concentration of 0.02-0.8 mol / L, generating a waste dilute sulfuric acid solution. The back-extraction stage comprises 3-8 stages using a sulfuric acid back-extraction solution at a concentration of 0.8-2.5 mol / L. The sulfuric acid waste liquid generated in the nickel and cobalt extraction and washing section can be collected and recycled into the preparation of dilute sulfuric acid solution for leaching.

[0101] The technical solution and effects of the present invention will be described below with reference to specific embodiments:

[0102] Example 1

[0103] The raw material, laterite nickel ore, 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%.

[0104] The following steps are used for the enrichment and separation of nickel, cobalt, and scandium:

[0105] 1) Add 2000g of nickel cobalt hydroxide (68.8% water content) made from laterite nickel ore to water at a liquid-to-solid ratio of 5:1 and mechanically stir to form a crude nickel cobalt hydroxide slurry. Then, further grind it with a colloid mill to refine the output particle size to below 10 micrometers.

[0106] 2) Introduce SO2 and oxygen at a flow rate of 6 L / min, with a volume fraction ratio of SO2 to oxygen of 20:100, for a reaction time of 10 min, at a temperature of 60℃, and with a solution pH of 4.0. Add 0.05 mol / L ferric sulfate solution as a catalyst for manganese oxidation and 0.01 mol / L copper sulfate solution as a catalyst for Fe(II) oxidation. Perform ultrasonic-enhanced oxidation at a frequency of 100 kHz for 5 min, while maintaining a constant temperature, to obtain an oxidized slurry.

[0107] 3) A dilute sulfuric acid solution was prepared by adding sulfuric acid and water to the extracted sulfuric acid waste liquid. This solution was then added to the oxidizing slurry for leaching. The liquid-to-solid ratio was 3.5:1, the pH was 1.5, the temperature was 55℃, the leaching time was 10 min, and the stirring intensity was 500 r / min. Solid-liquid separation was achieved by filtration, yielding manganese oxide slag and a purified first leachate. The manganese recovery rate was 87.1%.

[0108] 4) Iron removal by alum precipitation and scandium enrichment by co-precipitation: Sodium-containing waste liquid is added to the first leachate for iron and scandium removal by alum precipitation, ensuring that the molar ratio of added sodium ions to the total amount of iron, scandium, and scandium metal elements in the leachate is 1.5:1. The temperature of the leachate is controlled at 50°C, the stirring intensity at 200 r / min, and the precipitation time at 20 min. Filtration yields a second leachate (purified nickel-cobalt solution) rich in scandium, sodium, iron, and vanadium. The scandium enrichment and recovery rate reaches 98.5%.

[0109] 5) According to the molar ratio of organophosphorus extractant to hydroxyoxime extractant of 0.5:1, measure organophosphorus extractant P204 and hydroxyoxime extractant LIX63, add 260# solvent oil and mix mechanically to prepare a solvent oil solution containing 15% by volume of composite extractant, i.e., the synergistic extraction system formed by compounding; add the above synergistic extraction system to sodium hydroxide solution for organic phase saponification, so that the saponification rate is 40%, obtain saponified organic phase, and generate saponification waste liquid containing sodium sulfate.

[0110] 6) The saponified organic phase was used to perform cobalt kinetic extraction separation in the second leachate. The extraction equipment was a multi-stage centrifugal extractor with three-stage countercurrent extraction. The flow ratio of the saponified organic phase to the aqueous phase was 0.2:1. The extraction temperature was 35℃, the extraction time for each stage was 20 seconds, and the equilibrium pH of the aqueous phase was 3.5. Cobalt-loaded organic phase and raffinate containing nickel, calcium, and magnesium were obtained.

[0111] 7) The cobalt-loaded organic phase was washed in three stages with a 0.1 mol / L dilute sulfuric acid solution. The flow ratio of the organic phase to the aqueous phase was 6:1, yielding a washed cobalt-loaded organic phase and producing a waste dilute sulfuric acid solution. The washed cobalt-loaded organic phase was then back-extracted with a 1.5 mol / L sulfuric acid solution at a flow ratio of 5:1 to the aqueous phase, yielding a purified cobalt sulfate solution. The overall recovery rate of cobalt via extraction-washing-back-extraction reached 99.3%, and the purity of cobalt reached 99.9%.

[0112] 8) For nickel extraction separation of raffinate containing nickel, calcium, and magnesium, a multi-stage mixed-clarification extraction tank containing extraction, washing, and back-extraction sections was used. After three stages of countercurrent extraction at 20°C, the ratio of the organic phase to the aqueous phase in the saponification extraction was 1:1, the extraction time for each stage was 5 minutes, and the equilibrium pH of the aqueous phase was 3.5, yielding a nickel-loaded organic phase and a raffinate containing calcium and magnesium.

[0113] 9) The nickel-loaded organic phase was washed in four stages using a 0.5 mol / L dilute sulfuric acid solution, with an organic phase to aqueous phase flow ratio of 3:1. Then, the washed nickel-loaded organic phase was back-extracted using a 2 mol / L sulfuric acid solution in four stages, with an organic phase to aqueous phase flow ratio of 4:1, yielding a purified nickel sulfate solution. The overall recovery rate of nickel via extraction-washing-back-extraction reached 98.5%, and the purity of nickel reached 99.9%.

[0114] Example 2

[0115] The raw materials are the same as in Example 1.

[0116] The difference is that,

[0117] In step 5), organophosphate extractant P507 and hydroxyoxime extractant LIX63 are measured according to a molar ratio of organophosphate extractant to hydroxyoxime extractant of 5:1.

[0118] After testing,

[0119] The overall recovery rate of cobalt through extraction-washing-back-extraction reached 99.5%, and the purity of cobalt reached 99.9%.

[0120] The total recovery rate of nickel from extraction, washing, and back-extraction reached 98.6%, and the purity of nickel reached 99.8%.

[0121] Example 3

[0122] The raw materials are the same as in Example 1.

[0123] The difference is that,

[0124] In step 5), the organic phosphoric acid extractant Cyanex272 and the hydroxyoxime extractant LIX63 are measured according to a molar ratio of 0.1:1 between the organophosphoric acid extractant and the hydroxyoxime extractant.

[0125] After testing,

[0126] The overall recovery rate of cobalt through extraction-washing-back-extraction reached 99.4%, and the purity of cobalt reached 99.8%.

[0127] The total recovery rate of nickel from extraction, washing, and back-extraction reached 98.4%, and the purity of nickel reached 99.8%.

[0128] Example 4

[0129] The raw materials are the same as in Example 1.

[0130] Steps 1) and 3) are the same as in Example 1;

[0131] Step 2) Introduce SO2 and oxygen at a flow rate of 6 L / min, with a volume fraction ratio of SO2 to oxygen of 10:100, a reaction time of 12 min, a temperature of 70℃, and a solution pH of 4.5.

[0132] A 0.009 mol / L ferric sulfate solution was added as a catalyst for the manganese oxidation reaction, and a 0.02 mol / L copper sulfate solution was added as a catalyst for the Fe(II) oxidation reaction. Ultrasonic enhancement oxidation was performed at a frequency of 150 kHz (100 kHz) for 6 min at a temperature of 60 °C to obtain an oxidized slurry.

[0133] After testing,

[0134] The manganese recovery rate was 88.2%.

[0135] Comparative Example 1

[0136] The raw materials are the same as in Example 1.

[0137] Steps 1)-4) are the same as in Example 1.

[0138] Step 5) Instead of using a synergistic extraction system, cobalt extraction of the second leachate was performed using Lix63 extractant (a single extractant). The results showed that the cobalt extraction equilibrium was <5% at pH below 4.5.

[0139] Comparative Example 2

[0140] The raw materials are the same as in Example 1.

[0141] Steps 1) and 3) are the same as in Example 1;

[0142] Step 2) No catalyst was added, and no ultrasonic enhancement was performed. It was found that the oxidation of low-valence metals was very slow, and under otherwise identical conditions, the manganese recovery rate decreased, affecting the efficiency of subsequent nickel-cobalt extraction and separation.

[0143] 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 enriching and separating nickel, cobalt, and scandium, characterized in that, include: Step S1: Add water to nickel-cobalt hydroxide to form a slurry, thereby obtaining a slurry solution; Step S2: Sulfur dioxide and oxygen or air are introduced into the slurry for oxidation. The pH of the slurry is 2.0-6.

5. Fe(III)-containing reagent and Cu(II)-containing reagent are added, and the oxidation is enhanced by ultrasound to obtain an oxidized slurry. The volume fraction ratio of sulfur dioxide to oxygen is 5-30:

100. The Fe(III)-containing reagent is used as a manganese oxidation catalyst, and the concentration of Fe(III) ions is 0.001-0.1 mol / L. The Cu(II)-containing reagent is used as an iron oxidation catalyst, and the concentration of Cu(II) ions is 0.001-0.02 mol / L. Step S3: Add dilute sulfuric acid to the oxidizing slurry for selective leaching, and separate the solid and liquid to obtain the first leachate and manganese oxide slag; Step S4: Add an alkaline neutralizing agent or sulfuric acid to the first leachate to adjust the pH value of the first leachate to 0.6-3.

5. Use the iron alum ore method to precipitate vanadium and remove iron from the first leachate, and separate the solid and liquid to obtain scandium-rich iron alum slag and the second leachate. Step S5: An organophosphate extractant and a hydroxyoxime extractant are used to form a synergistic extraction system. The synergistic extraction system is saponified to obtain a saponified organic phase. The saponified organic phase is then used to perform kinetic extraction separation of nickel and cobalt in the second leachate. In this process, cobalt is preferentially extracted to obtain a cobalt-supported organic phase, which is then separated and purified to obtain the cobalt product. The cobalt extraction residue is then subjected to nickel extraction to obtain a nickel-supported organic phase, which is then separated and purified to obtain the nickel product.

2. The method for enrichment and separation of nickel, cobalt, and scandium according to claim 1, characterized in that, In step S2, Sulfur dioxide and oxygen or air are introduced into the slurry for oxidation, and the pH of the slurry is 4.0-5.5; The frequency of the ultrasound is 20kHz-200kHz; The oxidation reaction time is 2-20 min, and the temperature is 30-80℃; The enhanced oxidation reaction time is 5-10 min, and the temperature is 25-75℃.

3. The method for enrichment and separation of nickel, cobalt, and scandium according to claim 2, characterized in that, In step S2, The oxidation temperature is 50-70℃; The temperature for enhanced oxidation is 50-70℃.

4. The method for enrichment and separation of nickel, cobalt, and scandium according to claim 1, characterized in that, In step S5, The molar ratio of the organophosphate extractant to the hydroxyoxime extractant is 0.1-10:

1. The organophosphate extractant is one or more of P204, P507, and Cyanex272; The hydroxyoxime extractant is one or more of aliphatic α-hydroxyoxime extractants.

5. The method for enrichment and separation of nickel, cobalt, and scandium according to claim 4, characterized in that, In step S5, The molar ratio of the organophosphate extractant to the hydroxyoxime extractant is 0.5-5:1; The hydroxyoxime extractant is Lix63.

6. The method for enrichment and separation of nickel, cobalt, and scandium according to claim 4, characterized in that, In step S5, The organophosphate extractant and hydroxyoxime extractant are diluted with organic solvents, and the volume concentration of the extractant after dilution is 10-40%. The saponifying agent used in saponification is any one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, and ammonium carbonate; the saponification rate is 30-75%.

7. The method for enrichment and separation of nickel, cobalt, and scandium according to claim 6, characterized in that, Cobalt is preferentially extracted to obtain a cobalt-supported organic phase. The cobalt-supported organic phase is then washed, and the washed nickel-supported organic phase is back-extracted to obtain the cobalt product. Among them, multi-stage countercurrent extraction of cobalt is adopted. The number of extraction stages is 2-5, the flow ratio of saponified organic phase to aqueous phase is 0.05-1:1, the extraction temperature of each stage is 20-50℃, the extraction time of each stage is 5-120 seconds, and the equilibrium pH of the extraction aqueous phase is 1.0-3.

5. Washing section: The washing stage consists of 2-4 stages, and the washing solution is a dilute sulfuric acid solution with a concentration of 0.02-0.8 mol / L; Back-extraction stage: The back-extraction stage consists of 3-6 stages, using sulfuric acid back-extraction solution with a concentration of 1-3 mol / L.

8. The method for enrichment and separation of nickel, cobalt, and scandium according to claim 7, characterized in that, The cobalt extraction residue is then subjected to nickel extraction to obtain a nickel-loaded organic phase. The nickel-loaded organic phase is washed, and then the washed nickel-loaded organic phase is back-extracted to obtain the nickel product. Among them, multi-stage countercurrent extraction of nickel is adopted. The extraction stage has 5-10 extraction stages, the flow ratio of saponified organic phase to aqueous phase is 1-10:1, the extraction temperature of each stage is 30-60℃, the extraction time of each stage is 3-10 minutes, and the equilibrium pH of the extraction aqueous phase reaction is 2.0-4.

5. Washing section: The washing stage consists of 2-4 stages, and the washing solution is a dilute sulfuric acid solution with a concentration of 0.02-0.8 mol / L; Back-extraction stage: The number of back-extraction stages is 3-8, and sulfuric acid back-extraction solution is used with a concentration of 0.8-2.5 mol / L.

9. The method for enrichment and separation of nickel, cobalt, and scandium according to claim 8, characterized in that, Also includes: Collect the sulfuric acid waste liquid generated in the nickel and cobalt washing section in step S5 and recycle it in the preparation of the dilute sulfuric acid solution in step S3; The saponification waste liquid generated during saponification in step S5 is collected and recycled to step S4 to remove vanadium and iron from the first leaching solution using the iron alum ore method.

10. The method for enrichment and separation of nickel, cobalt, and scandium according to claim 1, characterized in that, Step S1 includes: adding water and mechanically stirring to form a coarse slurry; and using a colloid mill to finely grind the coarse slurry into a refined slurry; wherein the particle size of the solid particles in the refined slurry is 0.01-10 micrometers. And / or, in step S1, the amount of water added is determined based on the mass ratio of dry-basis nickel-cobalt hydroxide to water of 1:2-10.

11. The method for enrichment and separation of nickel, cobalt, and scandium according to claim 1, characterized in that, In step S3, The concentration of the dilute sulfuric acid is 0.5-3.5 mol / L; During selective leaching, the liquid-to-solid ratio of the leaching system is 20:1 to 1:1; the pH value of the leaching system is 0.5 to 2.5; the leaching temperature is 25 to 55℃; and the leaching time is 10 to 30 minutes.

12. The method for enrichment and separation of nickel, cobalt, and scandium according to claim 1, characterized in that, In step S4, the alkaline neutralizing agent is any one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, and ammonium carbonate. And / or, in step S4, when vanadium precipitation is carried out to remove iron, the molar ratio of the total amount of ammonium, sodium, and potassium in the reaction system to the total amount of iron and scandium in the leachate is 1.2-4.5:1; the temperature of the reaction system is 20-90℃; and the reaction time is 20-200min.

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