Method for comprehensive recovery of scandium, nickel, cobalt and manganese

Abstract

The application discloses a comprehensive recovery method of scandium, nickel, cobalt and manganese, and belongs to the technical field of metal production or refining. The method comprises the following steps: adding sulfuric acid to nickel cobalt hydroxide for leaching; introducing oxygen or air to oxidize the ferrous ions, so that an oxidized leaching solution is obtained; removing iron from the oxidized leaching solution by jarosite precipitation, so that a jarosite residue containing scandium and a second leaching solution are separated; introducing SO2 and oxygen / air into the second leaching solution to oxidize the divalent manganese, so that an oxidized manganese residue and a third leaching solution are separated; forming a composite extractant by mixing an organic phosphoric acid extractant and an organic carboxylic acid extractant; performing nickel cobalt extraction on the third leaching solution after saponification of the composite extractant; activating and roasting the jarosite residue containing scandium by using concentrated sulfuric acid, and then leaching the activated residue to obtain a fourth leaching solution; and performing scandium extraction on the fourth leaching solution by using the composite extractant, so that the scandium is separated and recovered to be separated from iron. The method can realize comprehensive recovery of scandium, manganese, nickel and cobalt, and can realize efficient extraction of nickel and cobalt and effective separation of the nickel and cobalt from other metals.

Description

Technical Field

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

[0002] Lateritic nickel ore has become a major nickel-cobalt resource, also containing 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 the nickel-cobalt hydroxide refining process is to remove impurities from the system to obtain nickel-cobalt metal or its compounds. Besides nickel and cobalt, nickel-cobalt hydroxide also contains iron and manganese. During the acid leaching reaction, nickel-cobalt hydroxide enters the leaching solution along with the nickel and cobalt, requiring a refining and separation process to remove iron and obtain a pure nickel-cobalt product.

[0003] 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.

[0004] Manganese is one of the impurities that are leached together with nickel and cobalt and processed in the subsequent separation process. Manganese interferes with the extraction of nickel and cobalt, affecting the purity of the product.

[0005] Scandium is present in a significant amount of nickel-cobalt hydroxide produced from laterite nickel ore. Scandium is a harmful impurity in nickel-cobalt smelting and is also a rare earth resource. The inventors have noted that, due to the low concentration of scandium in the system, the process of recovering scandium using only the scandium precipitation method suffers from low precipitation rate and difficulty in settling the precipitate. On the other hand, the process of extracting and separating scandium using acidic organophosphorus extractants such as P204 and P507 requires high-concentration alkaline solutions for back-extraction, which easily leads to difficulties in phase separation and low yield.

[0006] Existing nickel-cobalt extraction methods involve extraction and separation using acidic organophosphorus extractants such as P204, P507, and Cyanex 272 (P204 extraction - P507 cobalt extraction - Cyanex 272 deep extraction). However, the inventors have noticed that this process requires extraction at a high pH, ​​necessitates a large amount of neutralizing alkali, and generates a large amount of unusable salt- and acidic waste liquid during the saponification process of the extractant. To address the problem that ions such as iron, aluminum, manganese, calcium, and magnesium can easily interfere with the extraction of nickel and cobalt, iron, aluminum, and manganese need to be removed before extraction through precipitation or other methods, consuming a large amount of neutralizing alkali, and the resulting salt solution cannot be used.

[0007] Because the solution contains iron ions, including Fe 3+ Fe 2+In Chinese patent application CN103468948A, the method involves adjusting the pH 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, the inventors have discovered in practice 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 precisely control the endpoint pH. Too low a pH value leads to low scandium recovery, while too high a pH value results in colloidal precipitation, affecting filtration performance. Furthermore, conducting the reaction at a higher pH value increases the loss of nickel, cobalt, and manganese in the slag.

[0008] In Chinese patent CN115094229B, a reduction leaching process is performed on a nickel-cobalt hydroxide slurry, followed by iron removal from the leaching solution using a goethite method. This results in a goethite-type precipitate with adsorbed or doped scandium and a nickel-cobalt-containing solution, thereby enriching the scandium. However, the inventors have discovered that the reduction leaching causes manganese to become divalent, leading to a high manganese content in the nickel-cobalt solution. This, in turn, affects nickel-cobalt extraction and increases the difficulty of subsequent nickel-cobalt extraction.

[0009] Furthermore, the inventors have also noted that the treatment and utilization of iron alum containing other metals has always been a challenge in the industry, mainly because it is difficult to efficiently decompose iron alum and to efficiently separate and recover the valuable other metals contained therein; in addition, high-temperature roasting will cause sulfuric acid and sulfate to decompose, generating SO2 that pollutes the environment.

[0010] In view of this, the present invention is proposed. Summary of the Invention

[0011] According to one embodiment of the present invention, the objective is to provide a comprehensive method for the recovery of scandium, nickel, cobalt, and manganese.

[0012] The above objective can be achieved through the following technical solutions:

[0013] According to one aspect of the present invention, a comprehensive recovery method for scandium, nickel, cobalt, and manganese is provided, comprising:

[0014] Step S1: Add dilute sulfuric acid solution to nickel-cobalt hydroxide for leaching, and separate the solid and liquid to obtain the first leachate;

[0015] Step S2: Introduce oxygen or air into the first leachate to oxidize ferrous iron and obtain an oxidized leachate.

[0016] Step S3: Add alum precipitation reagent to the oxidative leachate to remove iron by alum precipitation using the iron alum ore method, and separate the solid and liquid to obtain scandium-containing iron alum residue and a second leachate;

[0017] Step S4: SO2 and oxygen / air are introduced into the second leachate to oxidize divalent manganese, and solid-liquid separation is performed to obtain manganese oxide slag and the third leachate.

[0018] Step S5: A composite extractant is formed by combining an organophosphate extractant and an organic carboxylic acid extractant;

[0019] Step S6: Saponify the composite extractant and use the saponified composite extractant to extract nickel and cobalt from the third leachate to separate and purify the nickel and cobalt product.

[0020] Step S7: Mix concentrated sulfuric acid with the scandium-containing iron alum slag for activation roasting to obtain activated scandium-containing iron alum slag; add dilute sulfuric acid solution to the activated scandium-containing iron alum slag for leaching, and filter to obtain the fourth leachate;

[0021] Step S8: The fourth leachate is subjected to scandium extraction using the composite extractant to obtain a scandium-loaded organic phase and an iron-containing raffinate.

[0022] Preferably, in step S1, the pH value of the leaching system is 1.0-6.5, and the leaching temperature is 15-45℃;

[0023] Preferably, in step S1, the concentration of the dilute sulfuric acid solution is 0.1-3 mol / L, and the liquid-solid ratio of the leaching system is 5:1-2:1.

[0024] Preferably, in step S1, the leaching time is 5-50 minutes.

[0025] Preferably, in step S2, before introducing oxygen or air, the following steps are included: adjusting the pH of the first leachate to 1.0-4.5; and during oxidation, the reaction temperature is 20-45°C.

[0026] Preferably, in step S2, the oxidation reaction time is 2-20 min.

[0027] Preferably, in step S2, before introducing oxygen or air, the process further includes adding a Cu(II) reagent as a catalyst for iron oxidation.

[0028] Preferably, the concentration of Cu(II) ions in the Cu(II)-containing reagent is 0.005-0.05 mol / L.

[0029] Preferably, step S3, before adding the alum precipitation reagent, further includes: adjusting the pH of the oxidative leachate to 0.5-3.0; the reaction temperature for alum precipitation to remove iron is 40-95℃, and the reaction time is 40-400 min;

[0030] Preferably, in step S3, after adding the alum precipitating reagent, the method further includes controlling the molar ratio of the total amount of ammonia, sodium, and potassium to the total amount of iron and scandium metal in the reaction system to be (1.1-5.5):1.

[0031] Preferably, the precipitating agent is a solution containing one or more sulfates of ammonia, sodium, and potassium.

[0032] Preferably, in step S4, before introducing SO2 and oxygen / air, the following steps are also included: adjusting the pH of the second leachate to 3.0-6.5; and setting the oxidation reaction temperature to 45-95°C.

[0033] Preferably, in step S4, the volume fraction ratio of SO2 to oxygen is (3-20):100; and the oxidation reaction time is 5-30 min.

[0034] Preferably, in step S4, before introducing SO2 and oxygen / air, the addition of a Fe(III)-containing reagent is also included.

[0035] Preferably, the concentration of Fe(III) ions in the Fe(III)-containing reagent is 0.001-0.1 mol / L.

[0036] Preferably, in step S5, the organic phosphoric acid extractant is one or more of P204, P507, and Cyanex 272; the organic carboxylic acid extractant is one or more of naphthenic acid, isomeric acid Versatic 10, and isomeric acid Versatic 911.

[0037] Preferably, the molar ratio of the organophosphate extractant to the organocarboxylic acid extractant is (0.1-10):1.

[0038] Preferably, the volume concentration of the extractant in the composite extractant is 5-50%; the diluent is any one or more selected from No. 5 solvent oil, No. 260 solvent oil, and sulfonated kerosene.

[0039] Preferably, in step S6, when performing nickel-cobalt extraction, the number of extraction stages is 3-6, the extraction temperature for each stage is 20-60℃, and the extraction time for each stage is 3-6 min; the ratio of the saponification extraction organic phase to the aqueous phase is (0.1-10):1; and the equilibrium pH of the extraction aqueous phase is 4.0-6.5.

[0040] Preferably, in step S6, after nickel-cobalt extraction, the process further includes: washing the extracted organic phase with dilute sulfuric acid; and back-extracting the washed extracted organic phase to obtain the nickel-cobalt product.

[0041] Preferably, the washing stage is 2-5 stages, and the concentration of the dilute sulfuric acid washing solution is 0.01-0.5 mol / L.

[0042] Preferably, the number of back-extraction stages is 3-8, and sulfuric acid back-extraction solution with a concentration of 0.5-5 mol / L is used during back-extraction.

[0043] Preferably, in step S7, the activation roasting temperature is 180-300℃; the mass ratio of concentrated sulfuric acid to scandium-iron alum slag is (0.1-0.45):1.

[0044] Preferably, in step S7, the liquid-solid ratio of the activated scandium-containing iron alum residue to the dilute sulfuric acid solution is 1:(2-8), the concentration of the dilute sulfuric acid solution is 2-15%, and the leaching temperature is 40-90℃.

[0045] Preferably, in step S8, the scandium extraction stage is 3-10 stages, the temperature is 20-60℃, the extraction time is 2-5 min, and the equilibrium pH of the aqueous phase reaction is 0.5-2.5.

[0046] Preferably, in step S8, after scandium extraction, the method further includes: using a precipitation back-extraction agent to perform precipitation back-extraction to obtain scandium precipitate; and calcining the scandium precipitate to obtain scandium oxide product.

[0047] Preferably, the precipitating stripping agent is one or more of oxalic acid, ammonium oxalate, citric acid, and ammonium citrate.

[0048] Preferably, the number of back-extraction stages is 3-6.

[0049] Preferably, the calcination temperature is 600-900℃ and the time is 2-4 hours.

[0050] Preferably, in steps S1-S4, an alkaline neutralizing agent or sulfuric acid is used to adjust the pH value of each reaction system; the alkaline neutralizing agent is one or more of ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and ammonium carbonate.

[0051] Preferably, in step S6, the saponifying agent used during saponification is one or more of ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and ammonium carbonate.

[0052] Preferably, the saponification rate is 10-60%.

[0053] Preferably, the saponification waste liquid generated during saponification is recycled to step S3 as an alum precipitating agent.

[0054] Beneficial effects: According to one embodiment of the present invention, the comprehensive recovery method for scandium, nickel, cobalt, and manganese involves first introducing oxygen or air into the acid leaching solution of nickel-cobalt hydroxide to oxidize ferrous ions to ferric ions. The ferric ions are then treated with alum precipitation reagent, utilizing the alum precipitation method to remove iron while simultaneously achieving scandium co-precipitation enrichment to form scandium-containing alum slag. Next, SO2 and oxygen / air are introduced into the purified nickel-cobalt leaching solution after iron and scandium removal to oxidize ferrous manganese to tetravalent manganese, forming manganese dioxide precipitate. After separation and recovery of manganese, a manganese-free solution is obtained. The purified nickel-cobalt solution is prepared by using a composite extractant consisting of an organophosphate extractant and an organocarboxylic acid extractant, followed by saponification, to extract the nickel and cobalt products. For the scandium-containing iron alum residue after iron removal from alum precipitation, it is first activated and roasted at low temperature to facilitate leaching. The activated and roasted scandium-containing iron alum residue is then leached to release scandium and iron. Scandium is then extracted using a composite extractant consisting of an unsaponified organophosphate extractant and an organocarboxylic acid extractant, separating and recovering the scandium and achieving separation from iron. In summary, this invention achieves comprehensive recovery of scandium, manganese, and nickel-cobalt, and realizes efficient extraction of nickel-cobalt and its effective separation from other metals.

[0055] Compared with the prior art, the present invention has the following advantages:

[0056] 1) Nickel-cobalt hydroxide is leached with sulfuric acid under normal pressure to leach nickel, cobalt, scandium, iron, and manganese. By adjusting the pH and temperature of the sulfuric acid leaching solution, and introducing oxygen / air, SO2, and oxygen / air, the intermediate products generated, such as SO5, are utilized. •- The strong oxidizing effect of free radical species was 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.

[0057] 2) In the stepwise oxidation process, ferrous iron is first rapidly oxidized to ferric iron to facilitate the formation of alum in the next step. Then, ferric iron ions are precipitated into alum. Iron is removed from the leachate containing ferric iron ions by using the (ammonium, sodium, potassium) alum ore formation method, which forms a precipitate of alum doped with or adsorbed with scandium. This achieves scandium enrichment. The resulting scandium-rich precipitate has a higher crystal structure and is easier to precipitate, wash and filter, with a low scandium loss rate.

[0058] 3) After iron is oxidized and alum is precipitated, the liquid after alum precipitation, which is the purified nickel-cobalt solution after removing iron and scandium, is then subjected to reaction conditions by introducing SO2 and oxygen / air to rapidly oxidize divalent manganese in the solution to tetravalent manganese, forming manganese dioxide precipitate. After the reaction is completed, the liquid and solid are separated, and manganese can be filtered out and the manganese product can be separated and recovered.

[0059] 4) Acidic organic extractant is used to extract nickel and cobalt, and a composite extractant formed by organic phosphoric acid extractant and organic carboxylic acid extractant is used. After saponification treatment, nickel and cobalt-containing solutions purified by manganese separation are used for nickel and cobalt extraction. Compared with a single extraction system, this composite extractant has higher extraction selectivity, higher nickel and cobalt extraction recovery rate, and better phase separation effect. Moreover, saponification further increases the nickel and cobalt extraction separation efficiency.

[0060] 5) In this invention, the oxidation precipitation method for recovering manganese and the iron alum method for precipitating iron to enrich scandium can both be formed at higher acidity, reducing the amount of alkali used for neutralization.

[0061] 6) For scandium-containing iron alum slag after iron removal by alum precipitation, this invention first decomposes it by sulfuric acid roasting at low temperature to activate the iron alum, which is more conducive to leaching and avoids the problem of SO2 pollution caused by high-temperature roasting above 300℃. Then, the activated and roasted scandium-containing iron alum slag is leached to fully release scandium and iron. Then, scandium extraction is performed using acidic organophosphorus extractant and organic carboxylic acid extractant to separate and recover scandium and separate it from iron. Compared with the extraction selectivity of a single extractant system, the extraction recovery rate of scandium is higher and the phase separation effect is better. This solves the current problem of processing and utilizing iron alum containing other metals.

[0062] 7) During the precipitation of alum, the present invention can also utilize the sulfate waste liquid containing one or more of ammonia, sodium, and potassium generated during the nickel-cobalt extraction and saponification process, and use the (ammonium, sodium, potassium) alum ore generation method to generate doped or adsorbed scandium and yellow ammonium alum, yellow sodium alum, and yellow potassium alum precipitates, so that the (ammonium, sodium, potassium) elements are recycled.

[0063] In addition, during saponification, an alkaline solution containing ammonia, sodium, and potassium is used for saponification with a nickel-cobalt composite extractant. After saponification, a solution containing ammonium sulfate, sodium sulfate, or potassium sulfate is produced. This saponification waste liquid can be recycled as a precipitating agent.

[0064] In addition, dilute sulfuric acid solution can be used as the washing liquid in the extraction and washing section. The sulfuric acid waste liquid generated after washing can also be used in the preparation of sulfuric acid solution for leaching, so as to realize the recycling of acid reagents and reduce raw material costs.

[0065] 8) After scandium extraction, the present invention may also use one or more of oxalic acid, ammonium oxalate, citric acid, and ammonium citrate as precipitating and back-extracting agents to precipitate and back-extract scandium to obtain scandium precipitate, which is then calcined to obtain scandium oxide product. Attached Figure Description

[0066] Figure 1 This is a process flow diagram of a comprehensive recovery method for scandium, nickel, cobalt, and manganese in one embodiment of the present invention. Detailed Implementation

[0067] 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.

[0068] To address the problems encountered in the refining of nickel-cobalt hydroxide to obtain nickel-cobalt products, such as the inability to efficiently extract nickel-cobalt to achieve effective separation from scandium, manganese, iron, calcium, and magnesium, the difficulties in processing iron alum, and the challenges in separating and recovering scandium;

[0069] This invention provides a comprehensive recovery method for scandium, nickel, cobalt, and manganese. It employs stepwise oxidation with Fe(II) and Mn(II) ions coupled with iron removal via an iron alum process and manganese separation via precipitation, achieving iron removal and scandium enrichment and recovery, respectively. Scandium-containing iron alum slag is activated and roasted with concentrated sulfuric acid and then leached with dilute sulfuric acid. Scandium is then extracted using a non-saponifiable (formed by organic carboxylic acid and organic phosphoric acid extractants) composite extractant, extracting scandium into the organic phase while iron enters the raffinate, thus achieving scandium and iron separation and recovery. For the manganese-purified nickel-cobalt solution, a saponifiable (formed by organic carboxylic acid and organic phosphoric acid extractants) composite extractant is used for nickel-cobalt extraction to separate and purify the nickel-cobalt product. This invention achieves comprehensive recovery of scandium, manganese, and nickel-cobalt, realizing efficient extraction of nickel-cobalt and effective separation from other metals.

[0070] The reaction principle and effects of each step in this invention are explained below:

[0071] 1) Nickel-cobalt hydroxide was leached with sulfuric acid at atmospheric pressure. After leaching nickel, cobalt, scandium, iron, and manganese, based on the differences in the effects of temperature and solution pH on the oxidation sequence of Fe(II) and Mn(II) ions, the reaction conditions were adjusted by introducing oxidants (oxygen / air and SO2 and oxygen / air) and utilizing the generated intermediate products such as SO5. •- The strong oxidizing effect of free radical species enables the stepwise oxidation of ferrous iron and manganese in the solution.

[0072] Ferrous iron (Fe2+) is rapidly oxidized to ferric iron (Fe3+). This ferric ion is then precipitated using alum ore, resulting in scandium co-precipitation and enrichment. This forms scandium-doped or scandium-adsorbed alum-type precipitates and a nickel-cobalt-containing solution. Simultaneously, iron impurities in the nickel-cobalt solution are removed, and scandium is enriched. The resulting scandium-rich precipitate has a higher crystal structure, is easier to precipitate, wash, and filter, and has a low scandium loss rate. Furthermore, during the alum precipitation process for removing iron and scandium, the sulfate (ammonium, sodium, potassium) waste liquid generated during the nickel-cobalt extraction and saponification process can be recycled. This waste liquid can then be used to remove iron using the (ammonium, sodium, potassium) alum ore formation method, forming scandium-doped or scandium-adsorbed alum-type precipitates (mainly jaundice, sodium jaundice, and ammonium jaundice). This process of iron precipitation and scandium co-precipitation enrichment allows for the recycling of elements.

[0073] The leaching solution after alum precipitation, which is the second leaching solution containing nickel, cobalt, and manganese purified by removing scandium and iron, is then purged with SO2 and oxygen / air. This rapidly oxidizes divalent manganese in the solution to tetravalent manganese, forming manganese dioxide precipitate. After the reaction is complete, liquid-solid separation occurs, and the manganese can be removed and recovered by filtration. The purified nickel-cobalt solution obtained after manganese separation can be used for subsequent nickel-cobalt extraction, which improves the efficiency of nickel-cobalt extraction and separation. In addition, the oxidation precipitation of manganese and scandium precipitation can be formed under higher acidity, reducing the need for alkali neutralization.

[0074] 2) A composite extractant, consisting of organic phosphoric acid and organic carboxylic acid extractants, is formed and saponified. This composite extractant is then used to extract nickel and cobalt from the purified nickel-cobalt solution (after iron, scandium, and manganese removal). This improves the selectivity and recovery rate of nickel-cobalt extraction, and enhances phase separation. Saponification further increases the separation efficiency of the nickel-cobalt extraction. Furthermore, the composite extractant is saponified using an alkaline solution containing one or more of ammonia, sodium, and potassium. The resulting solution contains ammonium sulfate, sodium sulfate, or potassium sulfate and can be used as a precipitating agent. Additionally, dilute sulfuric acid is used as the washing liquid in the extraction washing section. The resulting waste dilute sulfuric acid can be used in the preparation of dilute sulfuric acid for leaching, thus achieving acid recycling and reducing raw material costs.

[0075] 3) The scandium-containing iron alum slag is first decomposed by sulfuric acid roasting at low temperature to activate the iron alum and facilitate leaching, while avoiding the environmental pollution caused by SO2 generated by traditional high-temperature roasting methods. Then, the activated and roasted scandium-containing iron alum slag is leached with sulfuric acid to release scandium and iron. Scandium extraction is performed using a composite extractant (unsaponified) consisting of an acidic organophosphorus extractant and an organic carboxylic acid extractant, thereby separating and recovering scandium from iron, resulting in high scandium recovery and better phase separation. In summary, the above method has advantages such as high impurity separation efficiency, higher recovery rates of nickel, cobalt, manganese, and scandium, low loss rate, low equipment investment and operating costs, and the ability to recycle elements / reagents.

[0076] In some embodiments of the present invention, the method for complete separation and recovery of nickel, cobalt, scandium, manganese, and iron is provided, with reference to... Figure 1 As shown,

[0077] Includes the following steps:

[0078] Step S1: Add dilute sulfuric acid solution to nickel-cobalt hydroxide for leaching to leach nickel, cobalt, scandium, iron, and manganese. Perform a first solid-liquid separation on the leached slurry to obtain a first leaching residue and a first leaching solution.

[0079] The pH value of the leaching system is 1.0-6.5, preferably 2.0-5.0. The leaching temperature is 15-45℃, preferably 20-40℃. Under these conditions, nickel, cobalt, scandium, iron, and manganese can be leached more efficiently.

[0080] To further improve leaching efficiency, the liquid-to-solid ratio of the leaching system is preferably 5:1-2:1. Preferably, the concentration of the dilute sulfuric acid solution is 0.1-3 mol / L. The leaching time is preferably 5-50 min. Furthermore, the dilute sulfuric acid solution can be prepared using waste dilute sulfuric acid solution from the nickel-cobalt extraction washing section, water, and concentrated sulfuric acid.

[0081] Step S2: Introduce oxygen or air into the first leachate to oxidize ferrous ions to ferric ions, thereby obtaining an oxidized leachate.

[0082] To oxidize the iron first, an alkaline neutralizing agent or sulfuric acid is added before oxidation to adjust the pH of the first leachate and regulate the reaction temperature of the iron oxidation. Further, the pH is adjusted to 1.0-4.5, preferably 2.0-4.0. The reaction temperature is 20-45°C, preferably 30-40°C. Furthermore, the reaction time for this iron oxidation step can be 2-20 minutes.

[0083] To accelerate the iron oxidation reaction, a Cu(II)-containing reagent, such as copper sulfate solution, is added as a catalyst for the oxidation reaction. The concentration of Cu(II) ions in the Cu(II)-containing reagent is preferably 0.005-0.05 mol / L.

[0084] Step S3: Add alum precipitation reagent to the oxidative leachate to precipitate alum and remove iron, so as to remove scandium by using the alum ore method. After the reaction, an alum-type precipitate with adsorbed or doped scandium and a nickel-cobalt-containing solution are formed. Perform a second solid-liquid separation on the alum precipitate slurry after the reaction to obtain scandium-containing alum slag and a second leachate purified by removing scandium.

[0085] To facilitate the precipitation of alum and removal of iron and scandium, an alkaline neutralizing agent or sulfuric acid is first added to the oxidative leachate to adjust its pH to 0.5-3.0, preferably 1.0-1.5. The temperature of the reaction system is controlled at 40-95℃, preferably 60-90℃.

[0086] The precipitating agent is a salt solution containing one or more of ammonia, sodium, and potassium. More preferably, it is a sulfate solution containing one or more of ammonia, sodium, and potassium. Preferably, it is a waste salt solution containing ammonium sulfate, sodium sulfate, and potassium sulfate generated during the saponification process of the extractant.

[0087] To more efficiently remove iron and enrich scandium through precipitation, the molar ratio of the total amount of ammonia, sodium, and potassium to the total amount of iron and scandium metal in the reaction system is preferably controlled at 1.1-5.5:1. The precipitation reaction time is preferably 40-400 min. The reaction process can be stirred, with a stirring intensity preferably of 100-350 r / min.

[0088] Step S4: SO2 and oxygen / air are introduced into the second leachate to oxidize divalent manganese to tetravalent manganese and form manganese dioxide. The slurry after oxidation and precipitation is subjected to a third solid-liquid separation to obtain precipitated residue, i.e. manganese oxide residue, and a third leachate purified by removing manganese (purified nickel-cobalt solution).

[0089] By employing an oxidation precipitation method, manganese separation and recovery were achieved. The manganese oxide slag was processed to obtain manganese products, and a purified nickel-cobalt solution was obtained, which is more conducive to subsequent nickel-cobalt extraction and separation. To ensure more complete oxidation of divalent manganese, an alkaline neutralizing agent or sulfuric acid was added to the second leaching solution before oxidation to adjust the pH of the second leaching solution and the oxidation reaction temperature. Further, the pH was 3.0-6.5, preferably 4.0-6.0. The oxidation reaction temperature was 45-95℃, preferably 55-85℃.

[0090] For more efficient oxidation of manganese dioxide, the volume ratio of SO2 to oxygen is preferably 3-20:100. The oxidation reaction time is 5-30 min.

[0091] To further accelerate the manganese oxidation reaction, a Fe(III)-containing reagent, such as ferric sulfate solution, is added before oxidation to act as a catalyst. The concentration of Fe(III) ions in the Fe(III)-containing reagent is preferably 0.001-0.1 mol / L.

[0092] Step S5 involves using an organic phosphoric acid extractant and an organic carboxylic acid extractant to form a composite extractant.

[0093] Further, the organophosphate extractant is one or more of P204, P507, and Cyanex 272. The organic carboxylic acid extractant is one or more of naphthenic acid, isomeric acid Versatic 10, and isomeric acid Versatic 911. Preferably, the molar ratio of the organophosphate extractant to the organic carboxylic acid extractant is 0.1-10:1.

[0094] The composite extractant is prepared by dissolving an organophosphate extractant and an organocarboxylic acid extractant in an organic diluent. The organic diluent is selected from any one or more of 5# solvent oil, 260# solvent oil, and sulfonated kerosene. The volume concentration of the extractant in the composite extractant is 5-50%.

[0095] Step S6: Saponify the composite extractant and use the saponified composite extractant to extract nickel and cobalt from the third leachate obtained in step S4, so as to separate and purify the nickel and cobalt product.

[0096] During saponification, the saponifying agent is preferably one or more of ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and ammonium carbonate. The saponification rate is 10-60%. Saponification yields a saponified organic phase, which is then used for nickel-cobalt extraction. Furthermore, the waste liquid generated during saponification, containing one or more sulfates of ammonia, sodium, and potassium, can be recycled to step S3, i.e., used as a precipitation reagent for the (ammonia, sodium, potassium) alum ore method to remove scandium and iron.

[0097] Nickel-cobalt extraction involves multi-stage countercurrent extraction, washing, and back-extraction.

[0098] 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; the ratio of the saponification extraction organic phase to the aqueous phase is 0.1-10:1; the preferred equilibrium pH of the extraction aqueous phase is 4.0-6.5. After extraction, a nickel-cobalt extracted supported organic phase is obtained.

[0099] Washing section: The extracted organic phase is washed, preferably with 2-5 washing stages. The washing solution is a dilute sulfuric acid solution with a concentration preferably 0.01-0.5 mol / L. The sulfuric acid waste liquid generated during washing can be used to prepare sulfuric acid for leaching.

[0100] Back-extraction stage: The washed extract-supported organic phase is back-extracted to obtain nickel-cobalt products. The number of back-extraction stages is preferably 3-8 stages. Sulfuric acid back-extraction solution is used during back-extraction, and the concentration is preferably 0.5-5 mol / L.

[0101] Step S7: The scandium-containing iron alum slag obtained in step S3 is activated and roasted using concentrated sulfuric acid to obtain an activated scandium-containing iron alum slag that is easy to leach; the activated scandium-containing iron alum slag is leached using dilute sulfuric acid solution, and the leaching slurry is filtered, i.e., the fourth solid-liquid separation, to obtain the fourth leachate.

[0102] To improve the activation effect while avoiding the decomposition of sulfuric acid or sulfate, the preferred calcination temperature during activation is 180-300℃, such as 150℃, 180℃, 200℃, 220℃, 250℃, 280℃, 300℃, etc. If the calcination temperature is higher than 300℃, SO2 will be generated, polluting the environment.

[0103] Furthermore, the mass ratio of concentrated sulfuric acid to scandium-iron alum slag is preferably 0.1-0.45:1, for example 0.1:1; 0.2:1; 0.3:1; 0.4:1; 0.45:1, etc.

[0104] To achieve more efficient scandium leaching, the liquid-to-solid ratio of the activated scandium-containing iron alum residue to the dilute sulfuric acid solution is controlled at 1:2-8 during dilute sulfuric acid leaching, and the temperature is maintained at 40-90℃, such as 40℃, 50℃, 60℃, 70℃, 80℃, and 90℃. Furthermore, the concentration of the dilute sulfuric acid solution is 2-15%.

[0105] Step S8: Scandium extraction is performed on the fourth leachate using the unsaponified composite extractant obtained in step S5 to obtain a scandium-loaded organic phase and an iron-containing raffinate, thereby achieving the separation of scandium and iron.

[0106] Furthermore, scandium oxide is obtained by precipitation and back-extraction of the scandium-supported organic phase followed by calcination. The iron-containing raffinate can be processed to obtain iron products.

[0107] When using unsaponified composite extractants for scandium extraction,

[0108] Extraction stage: The scandium extraction stage is 3-10 stages, the preferred temperature is 20-60℃, and the extraction time is 2-5 min; preferably, the equilibrium pH of the aqueous phase reaction is 0.5-2.5. Under these preferred conditions, scandium can be extracted more efficiently and its effective separation from iron can be achieved.

[0109] Washing section: The washing section consists of 3-6 stages, using dilute sulfuric acid washing solution with a concentration of 0.01-0.1 mol / L. The sulfuric acid waste liquid generated during washing can be used to prepare sulfuric acid for leaching.

[0110] Precipitation back-extraction stage: The washed scandium-supported organic phase is back-extracted using a precipitation back-extraction agent to obtain scandium precipitate. The precipitation back-extraction agent is one or more of oxalic acid, ammonium oxalate, citric acid, and ammonium citrate, and the number of back-extraction stages is 3-6.

[0111] Calcination stage: The scandium precipitate is calcined to obtain scandium oxide product. The preferred calcination temperature is 600-900℃ and the time is 2-4h to obtain scandium oxide product with higher purity.

[0112] The technical solution and effects of the present invention will be described below with reference to specific embodiments:

[0113] Example 1

[0114] 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%.

[0115] Includes the following steps:

[0116] 1) 1000g of nickel-cobalt hydroxide produced from laterite nickel ore was added to a 0.3 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 3:1, the pH value was 3.0, the temperature was 20℃, and the leaching time was 20min. The first leachate was obtained by filtration.

[0117] 2) Adjust the pH of the first leachate to 1.0, the temperature to 20℃, add 0.01 mol / L copper sulfate solution as a catalyst for the oxidation reaction, and introduce air to oxidize ferrous iron. The reaction time is 10 min to obtain the oxidized leachate.

[0118] 3) Sulfuric acid was added to the oxidized leachate to control the pH value of the leachate at 0.5 and the temperature at 50°C. The stirring intensity was 200 r / min. Waste liquid containing ammonia, sodium, and potassium salts was added to precipitate alum and remove iron and scandium, ensuring that the molar ratio of the added ammonia, sodium, and potassium to the total amount of iron and scandium metal elements in the leachate was 1.1:1. The precipitation time was 50 min, and the product was filtered to obtain scandium-containing iron alum slag and a second leachate. The scandium enrichment and recovery rate reached 96.8%.

[0119] 4) An alkaline neutralizing agent was added to the second leachate to adjust its pH to 4.0. A 0.001 mol / L ferric sulfate solution was added as a catalyst for the oxidation reaction. SO2 and oxygen were then introduced to further oxidize the divalent manganese. The volume ratio of SO2 to oxygen was 5:100, the temperature was 45℃, and the reaction time was 20 min. The mixture was filtered to obtain manganese oxide slag and the third leachate. The manganese enrichment and recovery rate reached 95.5%.

[0120] 5) Prepare a composite extractant by mixing 25% organophosphate extractant P204 and 10% organic carboxylic acid extractant (naphthenic acid) in a No. 5 solvent oil solution. Saponify the above extractant using a saponifying agent (1 mol / L sodium hydroxide) with a saponification rate of 33%. The saponification yields a saponified organic phase and a saponification waste liquid containing sodium ions.

[0121] 6) The saponified organic phase was used for nickel-cobalt extraction separation from the third leaching solution. The extraction was performed in four stages of countercurrent extraction at 20°C, with an organic phase to aqueous phase ratio of 10:1 and an equilibrium pH of 6.5. The washing stage consisted of four stages, with the washing solution for the extracted organic phase being a 0.1 mol / L dilute sulfuric acid solution. The washed extracted organic phase was then subjected to six stages of back-extraction using a 2 mol / L sulfuric acid solution. The overall recovery rates of the extraction-washing-back-extraction process were 98.1% for nickel and 98.5% for cobalt.

[0122] 7) The scandium-containing iron alum slag is activated and roasted using concentrated sulfuric acid at a temperature of 180°C. The mass ratio of concentrated sulfuric acid to scandium-containing iron alum slag is 0.3:1. During leaching, the solid-liquid ratio of scandium-containing iron alum slag to dilute sulfuric acid solution is 1:3, the concentration of dilute sulfuric acid solution is 5%, and the temperature is 90°C, to obtain the fourth leachate.

[0123] 8) The fourth leachate was subjected to scandium extraction, washing, and precipitation back-extraction using an unsaponified composite extractant. The scandium extraction consisted of 5 stages at 20°C for 3 minutes, with the aqueous phase equilibrium pH at 1.5. The washing solution for the organic phase was a dilute sulfuric acid solution with 4 stages and a concentration of 0.05 mol / L. The back-extraction agent was an oxalic acid solution with 3 stages, yielding scandium oxalate. The scandium oxalate was then calcined at 900°C for 2 hours to obtain scandium oxide with a purity of 99.2%.

[0124] Example 2

[0125] The raw materials are the same as in Example 1.

[0126] Includes the following steps:

[0127] 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.

[0128] 2) Adjust the pH of the first leachate to 2.0 and the temperature to 30℃. Add 0.01 mol / L copper sulfate solution as a catalyst for the oxidation reaction, and introduce air to oxidize ferrous iron. The reaction time is 10 min to obtain the oxidized leachate.

[0129] 3) Sulfuric acid was added to the oxidized leachate to control the pH value at 1.0, the temperature of the leachate was controlled at 75℃, and the stirring intensity was 200 r / min. Waste liquid containing ammonia, sodium, and potassium salts was added to precipitate alum and remove iron and scandium, ensuring that the molar ratio of the added ammonia, sodium, and potassium to the total amount of iron, scandium, and scandium metal elements in the leachate was 1.5:1. The precipitation time was 100 min, and the mixture was filtered to obtain scandium-containing iron alum slag and a second leachate. The scandium enrichment and recovery rate reached 95.1%.

[0130] 4) An alkaline neutralizing agent was added to the second leachate to adjust its pH to 4.0. A 0.005 mol / L ferric sulfate solution was added as a catalyst for the oxidation reaction. SO2 and air were then introduced for oxidation, with a SO2 to oxygen volume ratio of 15:100. The temperature was 55℃, and the reaction time was 20 min. The mixture was filtered to obtain manganese oxide slag and the third leachate. The manganese enrichment and recovery rate reached 95.8%.

[0131] 5) Prepare a composite extractant by using a 260# solvent oil solution containing 15% organic phosphoric acid extractant P507 and 10% organic carboxylic acid extractant naphthenic acid; saponify the above extractant with a saponifying agent of 3 mol / L ammonia water, with a saponification rate of 60%, to obtain a saponified organic phase and a saponified waste liquid containing ammonium ions.

[0132] 6) The saponified organic phase was used for nickel-cobalt extraction separation from the third leaching solution. The extraction was performed using a 6-stage countercurrent extraction process at 40°C, with a saponified organic phase to aqueous phase ratio of 2:1 and an equilibrium pH of 5.5. The washing stage consisted of 4 stages, with the washing solution for the extracted organic phase being a 0.2 mol / L dilute sulfuric acid solution. The washed extracted organic phase was then subjected to a 3-stage back-extraction process using a 1 mol / L sulfuric acid solution. The overall recovery rates of the extraction-washing-back-extraction process were 98.3% for nickel and 98.1% for cobalt.

[0133] 7) The scandium-containing iron alum slag is activated and roasted using concentrated sulfuric acid at a temperature of 250°C. The mass ratio of concentrated sulfuric acid to scandium-containing iron alum slag is 0.45:1. During leaching, the solid-liquid ratio of scandium-containing iron alum slag to dilute sulfuric acid solution is 1:5, the concentration of dilute sulfuric acid solution is 15%, and the temperature is 70°C, to obtain the fourth leachate.

[0134] 8) The fourth leachate was subjected to scandium extraction, washing, and precipitation back-extraction using an unsaponified composite extractant. The scandium extraction consisted of three stages at 40°C for 4 minutes, with the aqueous phase equilibrium pH at 1.0. The washing solution for the organic phase was a dilute sulfuric acid solution with four stages and a concentration of 0.03 mol / L. The precipitation back-extraction agent used in the scandium extraction was an ammonium oxalate solution with five stages, yielding scandium oxalate. The scandium oxalate was then calcined at 850°C for 3 hours to obtain scandium oxide with a purity of 99.3%.

[0135] Example 3

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

[0137] Includes the following steps:

[0138] 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.

[0139] 2) Adjust the pH of the sulfuric acid leaching solution 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 introduce air to oxidize ferrous iron. The reaction time is 10 min to obtain the oxidized leaching solution.

[0140] 3) Sulfuric acid was added to the oxidized leachate to control the pH value at 3.0, the temperature of the leachate was controlled at 90℃, and the stirring intensity was 200 r / min. Waste liquid containing ammonia, sodium, and potassium salts was added to precipitate alum and remove iron and scandium, ensuring that the molar ratio of the added ammonia, sodium, and potassium to the total amount of iron, scandium, and scandium metal elements in the leachate was 2.5:1. The precipitation time was 200 min, and the product was filtered to obtain scandium-containing iron alum slag and a second leachate. The scandium enrichment and recovery rate reached 95.6%.

[0141] 4) An alkaline neutralizing agent was added to the second leachate to adjust its pH to 5.0. A 0.05 mol / L ferric sulfate solution was added as a catalyst for the oxidation reaction. SO2 and air were then introduced for oxidation, with a SO2 to oxygen volume ratio of 20:100. The temperature was 55℃, and the reaction time was 30 min. The mixture was filtered to obtain manganese oxide slag and the third leachate. The manganese enrichment and recovery rate reached 95.9%.

[0142] 5) Prepare a sulfonated kerosene solution containing 30% organic phosphoric acid extractant Cyanex 272 and 15% isomeric acid Versatic 10 to form a composite extractant; use the above extractant solution as a saponifying agent with a 2 mol / L potassium carbonate solution, with a saponification rate of 20%, and obtain a saponified organic phase and a saponified waste liquid containing potassium ions.

[0143] 6) The saponified organic phase was used for nickel-cobalt extraction and separation from the third leaching solution via four-stage countercurrent extraction at 40°C. The ratio of the saponified organic phase to the aqueous phase was 1:1, and the equilibrium pH of the aqueous phase was 4.5. The washing stage consisted of four stages, with the washing solution for the extracted organic phase being a 0.2 mol / L dilute sulfuric acid solution. The washed extracted organic phase was then subjected to six stages of back-extraction using a 3 mol / L sulfuric acid solution. The overall recovery rates of the extraction-washing-back-extraction process were 98.5% for nickel and 98.7% for cobalt.

[0144] 7) The scandium-containing iron alum slag is activated and roasted using concentrated sulfuric acid at a temperature of 300°C. The mass ratio of concentrated sulfuric acid to scandium-containing iron alum slag is 0.15:1. During leaching, the solid-liquid ratio of scandium-containing iron alum slag to dilute sulfuric acid solution is 1:7, the concentration of dilute sulfuric acid solution is 5%, and the temperature is 50°C, to obtain the fourth leachate.

[0145] 8) The fourth leachate was subjected to scandium extraction, washing, and precipitation back-extraction using an unsaponified composite extractant. The scandium extraction consisted of three stages at 40°C for 3 minutes; the equilibrium pH of the aqueous phase was 1.5; the washing solution for the organic phase was a dilute sulfuric acid solution with four stages and a concentration of 0.1 mol / L; the precipitation back-extraction agent used in the scandium extraction was ammonium citrate solution with five stages, yielding scandium citrate. The scandium citrate was then calcined at 650°C for 2 hours to obtain scandium oxide with a purity of 99.1%.

[0146] Example 4

[0147] The raw materials are the same as in Example 1.

[0148] Includes the following steps:

[0149] 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.

[0150] 2) Adjust the pH of the sulfuric acid leaching solution 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 introduce air to oxidize ferrous iron. The reaction time is 5 min to obtain the oxidized leaching solution.

[0151] 3) Sulfuric acid was added to the oxidized leachate to control the pH value of the leachate at 1.5, the temperature of the leachate was controlled at 90℃, and the stirring intensity was 200 r / min. Waste liquid containing ammonia, sodium, and potassium salts was added to precipitate alum and remove iron and scandium, ensuring that the molar ratio of the added ammonia, sodium, and potassium to the total amount of iron, scandium, and scandium metal elements in the leachate was 4.5:1. The precipitation time was 300 min, and the product was filtered to obtain scandium-containing iron alum slag and a second leachate. The scandium enrichment and recovery rate reached 96.1%.

[0152] 4) An alkaline neutralizing agent was added to the second leachate to adjust its pH to 5.0. A 0.05 mol / L ferric sulfate solution was added as a catalyst for the oxidation reaction. SO2 and oxygen were then introduced for oxidation, with a SO2 to oxygen volume ratio of 20:100. The temperature was 85℃, and the reaction time was 20 min. The mixture was filtered to obtain manganese oxide slag and the third leachate. The manganese enrichment and recovery rate reached 96.2%.

[0153] 5) Prepare a sulfonated kerosene solution containing 20% ​​organophosphate extractant Cyanex272, 10% organophosphate extractant P507 and 10% organocarboxylic acid extractant isomeric acid Versatic 10; use the above extractant solution as a saponifying agent with 4 mol / L ammonium carbonate solution, the saponification rate is 40%, and saponification yields a saponified organic phase and a saponification waste liquid containing ammonium ions.

[0154] 6) The saponified organic phase was used for nickel-cobalt extraction and separation from the third leaching solution via a 6-stage countercurrent extraction process at 40°C. The ratio of the saponified organic phase to the aqueous phase was 0.5:1, and the equilibrium pH of the aqueous phase was 4.0. The washing stage consisted of 5 stages, with the washing solution for the extracted organic phase being a 0.5 mol / L dilute sulfuric acid solution. The washed extracted organic phase was then subjected to a 6-stage back-extraction process using a 5 mol / L sulfuric acid solution. The overall recovery rates of the extraction-washing-back-extraction process were 98.9% for nickel and 98.5% for cobalt.

[0155] 7) The scandium-containing iron alum slag is activated and roasted using concentrated sulfuric acid at a temperature of 200°C. The mass ratio of concentrated sulfuric acid to scandium-containing iron alum slag is 0.25:1. During leaching, the solid-liquid ratio of scandium-containing iron alum slag to dilute sulfuric acid solution is 1:3.5, the concentration of dilute sulfuric acid solution is 15%, and the temperature is 60°C, to obtain the fourth leachate.

[0156] 8) The fourth leachate is subjected to scandium extraction, washing, and precipitation back-extraction using an unsaponified composite extractant. Preferably, the scandium extraction has 6 stages, a temperature of 40°C, and an extraction time of 4 min. Preferably, the equilibrium pH of the aqueous phase reaction is 2.0. Preferably, the washing solution for the organic phase loaded in the extraction is a dilute sulfuric acid solution with 5 washing stages and a concentration of 0.01 mol / L. The precipitation back-extraction agent used in the scandium extraction is an ammonium oxalate solution with 5 back-extraction stages, yielding scandium oxalate. Then, the scandium oxalate is calcined at 800°C for 3 h to obtain scandium oxide product with a purity of 99.2%.

[0157] Comparative Example 1

[0158] The raw materials are the same as in Example 1.

[0159] Steps 1)-4) are the same as in Example 1.

[0160] Step 5) Saponification was performed using a 35% organic phosphoric acid extractant P204 in a No. 5 solvent oil solution. The saponifying agent was 1 mol / L sodium hydroxide, and the saponification rate was 40%. The saponified organic phase was obtained.

[0161] Step 5) The saponified organic phase described above is used for nickel-cobalt extraction separation from the third leaching solution. The extraction is performed in 5 stages of countercurrent extraction at 25°C, with a saponified organic phase to aqueous phase ratio of 10:1 and an equilibrium pH of 6.5 for the aqueous phase. The washing stage consists of 4 stages, with the washing solution for the extracted organic phase being a 0.1 mol / L dilute sulfuric acid solution. The washed extracted organic phase is then subjected to 6 stages of back-extraction using a 2 mol / L sulfuric acid solution.

[0162] The overall recovery rates of extraction-washing-back-extraction were 97.8% for nickel and 98.0% for cobalt.

[0163] Comparative Example 2

[0164] The raw materials are the same as in Example 2.

[0165] Steps 1)-3) are the same as in Example 2;

[0166] Step 4) Prepare a composite extractant consisting of 15% organic phosphoric acid extractant P507 and 10% organic carboxylic acid extractant naphthenic acid in 260# solvent oil; saponify the above extractant with a saponifying agent of 3 mol / L ammonia water, with a saponification rate of 60%, to obtain a saponified organic phase and a saponified waste liquid containing ammonium ions.

[0167] Step 5) The saponified organic phase is directly extracted and separated from the second leaching solution in Step 3) using the above-mentioned saponified organic phase. The extraction is performed in 6 stages of countercurrent extraction at 40°C, with a saponified organic phase to aqueous phase ratio of 2:1 and an equilibrium pH of 5.5 for the aqueous phase. The washing stage consists of 4 stages, with the washing solution for the extracted organic phase being a 0.2 mol / L dilute sulfuric acid solution. The washed extracted organic phase is then subjected to 3 stages of back-extraction using a 1 mol / L sulfuric acid solution.

[0168] Example 2 and Comparative Example 2 were further processed using the same method to separate and purify nickel and cobalt products. The purity of the nickel and cobalt products was tested, and it was found that the purity of both the nickel and cobalt products obtained by direct extraction without removing manganese in Comparative Example 2 was lower than that of the nickel and cobalt products in Example 2.

[0169] Comparative Example 3

[0170] The raw materials are the same as in Example 3.

[0171] Steps 1) to 3) are the same as in Example 3;

[0172] Step 4) The scandium-iron alum residue is not activated and roasted, but directly leached with dilute sulfuric acid under the same leaching conditions as in Example 3, to obtain the fourth leachate;

[0173] The leaching rate of scandium in the fourth leachate of Comparative Example 3 and Example 3 was tested, and it was found that the leaching rate of unactivated roasted scandium in Comparative Example 3 was lower than that in Example 3.

[0174] Comparative Example 4

[0175] The raw materials are the same as in Example 4.

[0176] Steps 1) to 3) are the same as in Example 4;

[0177] Step 4) is the same as step 7) in Example 4;

[0178] Step 5) involves using a sulfonated kerosene solution containing 30% organophosphoric acid to extract scandium from the fourth leachate. The conditions for scandium extraction, washing, precipitation back-extraction, and calcination are the same as in Example 4 (Step 8), yielding scandium oxide.

[0179] The scandium recovery rates in Comparative Example 3 and Example 4 were tested, and it was found that the scandium recovery rate of Comparative Example 4 using only extractant P507 was lower than that of Example 4.

[0180] In summary, this invention achieves stepwise oxidation of iron and manganese by adjusting the pH and temperature of the nickel-cobalt hydroxide sulfuric acid leaching solution and introducing an oxidant. It also couples this with an iron alum method for iron removal and scandium co-precipitation, resulting in high scandium enrichment and recovery. Furthermore, it utilizes a precipitation method to separate and recover manganese, achieving a high manganese recovery rate. The invention employs a composite extractant formed by saponified organic carboxylic acid extractant and organic phosphoric acid extractant to extract nickel and cobalt from the purified solution after manganese separation, resulting in a high overall recovery rate of nickel and cobalt. Finally, by first mixing and roasting the scandium-containing iron alum slag with concentrated sulfuric acid to activate the iron alum, it achieves more efficient leaching, releasing scandium and iron. Then, unsaponified scandium is extracted using a composite extractant formed by organic carboxylic acid extractant and organic phosphoric acid extractant, achieving efficient scandium extraction and effective separation from iron. Through precipitation and back-extraction, a high-purity scandium oxide product can be obtained.

[0181] 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 comprehensive method for the recovery of scandium, nickel, cobalt, and manganese, characterized in that, include: Step S1: Add dilute sulfuric acid solution to nickel-cobalt hydroxide for leaching, and separate the solid and liquid to obtain the first leachate; Step S2: Adjust the pH of the first leachate to 1.0-4.5, introduce oxygen or air into the first leachate to oxidize ferrous iron, and the reaction temperature is 20-45℃ to obtain an oxidized leachate. Step S3: Add alum precipitation reagent to the oxidative leachate to remove iron by alum precipitation using the iron alum ore method, and separate the solid and liquid to obtain scandium-containing iron alum residue and a second leachate; Step S4: Adjust the pH of the second leachate to 3.0-6.5, introduce SO2 and oxygen / air into the second leachate to oxidize divalent manganese. The oxidation reaction temperature is 45-95℃. Solid-liquid separation is performed to obtain manganese oxide slag and the third leachate. The volume fraction ratio of SO2 to oxygen introduced is (3-20):

100. Step S5: A composite extractant is formed by combining an organophosphate extractant and an organic carboxylic acid extractant; Step S6: Saponify the composite extractant and use the saponified composite extractant to extract nickel and cobalt from the third leachate to separate and purify the nickel and cobalt product. Step S7: Mix concentrated sulfuric acid with the scandium-containing iron alum slag for activation roasting to obtain activated scandium-containing iron alum slag; add dilute sulfuric acid solution to the activated scandium-containing iron alum slag for leaching, and filter to obtain the fourth leachate; Step S8: The fourth leachate is subjected to scandium extraction using the composite extractant to obtain a scandium-loaded organic phase and an iron-containing raffinate.

2. The comprehensive recovery method for scandium, nickel, cobalt, and manganese according to claim 1, characterized in that, In step S1, the pH value of the leaching system is 1.0-6.5, and the leaching temperature is 15-45℃; And / or, the concentration of the dilute sulfuric acid solution is 0.1-3 mol / L, the liquid-solid ratio of the leaching system is 5:1-2:1, and the leaching time is 5-50 min.

3. The comprehensive recovery method for scandium, nickel, cobalt, and manganese according to claim 1, characterized in that, In step S2, the oxidation reaction time is 2-20 min; And / or, in step S2, before introducing oxygen or air, the method further includes: adding a reagent containing divalent copper ions as a catalyst for iron oxidation; wherein the concentration of divalent copper ions in the reagent containing divalent copper ions is 0.005-0.05 mol / L.

4. The comprehensive recovery method for scandium, nickel, cobalt, and manganese according to claim 1, characterized in that, Step S3, before adding the alum precipitation reagent, also includes: adjusting the pH of the oxidative leachate to 0.5-3.0; the reaction temperature for alum precipitation to remove iron is 40-95℃, and the reaction time is 40-400 min; And / or, in step S3, after adding the alum precipitation reagent, the method further includes: controlling the molar ratio of the total amount of ammonia, sodium, and potassium to the total amount of iron and scandium metals in the reaction system to be (1.1-5.5):1; wherein the alum precipitation reagent is a solution containing one or more sulfates of ammonia, sodium, and potassium.

5. The comprehensive recovery method for scandium, nickel, cobalt, and manganese according to claim 1, characterized in that, In step S4, the oxidation reaction time is 5-30 min; and / or, in step S4, before introducing SO2 and oxygen / air, the following is also included: adding a reagent containing ferric ions, wherein the concentration of ferric ions in the reagent containing ferric ions is 0.001-0.1 mol / L.

6. The comprehensive recovery method for scandium, nickel, cobalt, and manganese according to claim 1, characterized in that, In step S5, One or more of the organophosphate extractants P204, P507, and Cyanex 272; The organic carboxylic acid extractant is one or more of the following: cycloalkanoic acid, isomeric acid Versatic 10, and isomeric acid Versatic 911; The molar ratio of the organophosphate extractant to the organocarboxylic acid extractant is (0.1-10):1; The volume concentration of the extractant in the composite extractant is 5-50%; the diluent is any one or more selected from No. 5 solvent oil, No. 260 solvent oil, and sulfonated kerosene.

7. The comprehensive recovery method for scandium, nickel, cobalt, and manganese according to claim 1, characterized in that, In step S6, during nickel-cobalt extraction, the number of extraction stages is 3-6, the extraction temperature for each stage is 20-60℃, and the extraction time for each stage is 3-6 min; the ratio of the organic phase to the aqueous phase in the saponification extraction is (0.1-10):1; the equilibrium pH of the aqueous phase in the extraction reaction is 4.0-6.

5. And / or, in step S6, after nickel-cobalt extraction, the process further includes: washing the extracted organic phase with dilute sulfuric acid; and back-extracting the washed extracted organic phase to obtain the nickel-cobalt product; wherein, The washing stages are 2-5, and the concentration of the dilute sulfuric acid washing solution is 0.01-0.5 mol / L; The number of back-extraction stages is 3-8, and sulfuric acid back-extraction solution with a concentration of 0.5-5 mol / L is used during back-extraction.

8. The comprehensive recovery method for scandium, nickel, cobalt, and manganese according to claim 1, characterized in that, In step S7, the activation roasting temperature is 180-300℃; the mass ratio of concentrated sulfuric acid to scandium-iron alum slag is (0.1-0.45):1; And / or, in step S7, the liquid-solid ratio of the activated scandium-containing iron alum residue to the dilute sulfuric acid solution is 1:(2-8), the concentration of the dilute sulfuric acid solution is 2-15%, and the leaching temperature is 40-90℃.

9. The comprehensive recovery method for scandium, nickel, cobalt, and manganese according to claim 1, characterized in that, In step S8, the scandium extraction stage is 3-10, the temperature is 20-60℃, and the extraction time is 2-5 min; the equilibrium pH of the aqueous phase reaction is 0.5-2.

5. And / or, in step S8, after scandium extraction, the method further includes: performing precipitation back-extraction using a precipitation back-extraction agent to obtain scandium precipitate; calcining the scandium precipitate to obtain scandium oxide product; wherein the precipitation back-extraction agent is one or more of oxalic acid, ammonium oxalate, citric acid, and ammonium citrate; the number of back-extraction stages is 3-6; the calcination temperature is 600-900℃, and the time is 2-4h.

10. The comprehensive recovery method for scandium, nickel, cobalt, and manganese according to claim 1, characterized in that, In steps S1-S4, an alkaline neutralizing agent or sulfuric acid is used to adjust the pH value of each reaction system; the alkaline neutralizing agent is one or more of ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and ammonium carbonate. In step S6, the saponifying agent used during saponification is one or more of ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and ammonium carbonate; the saponification rate is 10-60%; the saponification waste liquid generated during saponification is recycled to step S3 as alum precipitation reagent.

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