A method for separating impurities from crude nickel-cobalt hydroxide and application thereof

Abstract

The application discloses a method for separating impurities from crude nickel-cobalt hydroxide and application thereof, and belongs to the field of hydrometallurgy. The method comprises the following steps: mixing the crude nickel-cobalt hydroxide with a phosphorus-iron liquid to prepare a slurry, adjusting pH to react, then adding a pH regulator, and after solid-liquid separation, obtaining a primary leaching liquid and a primary leaching residue; mixing the primary leaching residue with a leaching agent, adjusting pH to leach, then performing solid-liquid separation, and after sequentially removing copper and scandium from the obtained secondary leaching liquid, obtaining a first impurity-removed liquid; after the first impurity-removed liquid is warmed, adjusting pH to precipitate aluminum, then adding an oxidizing agent to precipitate iron, after solid-liquid separation, taking a liquid phase to obtain a second impurity-removed liquid; after the primary leaching liquid is mixed with the second impurity-removed liquid and warmed, adjusting pH to remove silicon, and after solid-liquid separation, obtaining a nickel-cobalt-containing solution and a silicon-removed residue. Thus, the impurities in the crude nickel-cobalt hydroxide can be separated in stages.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgy, specifically relating to a method for separating impurities from crude nickel-cobalt hydroxide and its application. Background Technology

[0002] Currently, the rapid development of new energy vehicles has led to a sharp increase in demand for nickel sulfate, a raw material for power batteries. Laterite nickel ore has become the most important source of nickel resources, but the nickel-cobalt hydroxide (MHP) intermediate obtained from its smelting has a complex composition, containing various metallic impurities (such as Cu, Fe, Al, Si, etc.) and associated strategic rare metal scandium. Existing technologies struggle to achieve selective separation of impurities and efficient recovery of scandium in an economical and environmentally friendly manner.

[0003] Based on this, the present invention is proposed. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a method for separating impurities from crude nickel cobalt hydroxide (MHP), which can efficiently separate impurities from crude MHP, thereby solving the problems of high cost and complex process in the prior art and realizing comprehensive resource utilization and clean production.

[0005] The present invention also proposes an application of the above method in mineral resource regeneration.

[0006] According to a first aspect of the present invention, a method for separating impurities from crude nickel cobalt hydroxide is provided, comprising the following steps: S1: Mix crude nickel-cobalt hydroxide with ferric phosphorus solution to form a slurry, adjust the pH to 0.5~1.0 to carry out the reaction, and then add a pH adjuster to make the pH 5.4~6.5. After solid-liquid separation, a primary leaching solution and a primary leaching residue are obtained. S2: Mix the primary leaching residue with the leaching agent, adjust the pH to 0.5~1.0 for leaching, then perform solid-liquid separation, and sequentially remove copper and scandium from the obtained secondary leaching solution to obtain the first impurity-removed solution; S3: After heating the first purified liquid, adjust the pH to 4.1~4.4 to precipitate aluminum, then add an oxidant to precipitate iron. After solid-liquid separation, take the liquid phase to obtain the second purified liquid. S4: Mix the first leaching solution from step S1 with the second impurity-removed solution from step S3, raise the temperature, adjust the pH to 6.3~6.5 to remove silicon, and then separate the solid and liquid to obtain a nickel-cobalt-containing solution and silicon-removed slag.

[0007] The main components of the crude nickel-cobalt hydroxide used in this invention are as follows (in weight percentage): Ni: 15%~22%, Co: 1%~3%, Mn: 2%~4%, Cu: 0.05%~0.24%, Fe: 0.1%~0.3%, Al: 0.05%~0.18%, Si: 0.04%~0.24%, Sc: 0.01%~0.06%.

[0008] In some embodiments, before step S2, the method further includes: reusing the primary leaching residue for the pulping operation in step S1, and repeating step S1 two to three times. Repeated leaching of the primary leaching residue can achieve the enrichment of impurities such as scandium.

[0009] In some embodiments, steps S1 and S2 independently use sulfuric acid to adjust the pH to 0.5-1.0; and / or steps S3 and S4 independently use a 10%-15% (w / w) sodium carbonate solution to adjust the pH. Specifically, the sodium carbonate solution is added in step S3 at a rate of 1.5-3 minutes per minute. 3 / h.

[0010] In some embodiments, the method further includes: S5: After mixing the desiliconized slag from step S4 with concentrated sulfuric acid to form a slurry, water is added to continue the reaction. After solid-liquid separation, silica and a nickel-aluminum acid leaching solution are obtained. The nickel-aluminum acid leaching solution is reused in the leaching operation of step S2. This invention directly converts amorphous hydrated silica slag containing nickel and aluminum into high-purity silica byproducts through carbonization treatment. This process achieves deep separation of silicon from nickel and aluminum; the nickel-aluminum acid leaching solution after separation is returned to the main system to recover valuable metals, while the purified silica can be sold as an industrial raw material. This approach eliminates waste emissions while realizing the high-value utilization of silicon resources and significantly improves the green level of the process.

[0011] In some embodiments, step S2, before the solid-liquid separation, further includes adding hydrogen peroxide until the liquid phase becomes clear. The reaction solution is black and turbid before the addition of hydrogen peroxide, and turns clear and green after the addition. Hydrogen peroxide can reduce the high-valence nickel, cobalt, and manganese in the primary leaching residue, which is beneficial for complete leaching.

[0012] In some embodiments, in step S1, the pH adjuster is selected from crude nickel cobalt hydroxide; and / or, in step S2, the leaching agent includes at least one of water or sulfuric acid; and / or, in step S3, the oxidant is selected from hydrogen peroxide.

[0013] In some embodiments, step S2 includes the following steps: mixing the secondary leaching solution with atomized iron powder and reacting them, followed by solid-liquid separation to obtain copper-removed liquid and sponge copper. The scandium removal process includes: adjusting the pH of the copper-removed solution to 2.5-3.5 for reaction, and then performing solid-liquid separation to obtain the first impurity-removed solution and scandium residue.

[0014] In some preferred embodiments, during the copper removal process, the mass of the atomized iron powder is 0.85 to 0.9 times the copper content in the secondary leaching solution, and the reaction is a stirred reaction for 1 hour.

[0015] This invention uses atomized iron powder instead of traditional reduced iron powder for copper removal. Atomized iron powder, due to its dense particles, smooth surface, and low oxygen content, allows for a milder and more controllable reaction process under the same acidic environment. It also exhibits higher selectivity for copper ion replacement, effectively suppressing the hydrogen evolution side reaction and significantly improving operational safety. Compared to reduced iron powder, this method not only reduces the consumption of iron powder but also decreases the introduction of impurity iron, thereby saving on reagent costs in subsequent iron removal processes, while achieving a more efficient and stable copper removal effect.

[0016] In some preferred embodiments, the particle size of the atomized iron powder is 40-80 mesh.

[0017] In some preferred embodiments, during the scandium removal process, a 10% to 15% sodium carbonate solution is used to adjust the pH; the reaction temperature is 20 to 60°C, and the reaction time is 20 to 60 minutes.

[0018] In some embodiments, in step S3, the temperature rise is to 60-65°C; and / or, the oxidant is added at a rate of 1-2 m... 3 / h.

[0019] Addressing the three major technical bottlenecks in traditional iron and aluminum removal processes—high nickel and cobalt content in the precipitate (leading to significant entrainment losses), high reaction temperatures (85-95℃), and difficulties in solid-liquid separation—this invention proposes a stepwise precipitation optimization process of "aluminum precipitation first, iron precipitation later," achieving a dual improvement in main metal recovery rate and solid-liquid separation efficiency without relying on high temperatures. First, this invention controls the aluminum precipitation reaction temperature at 60-65℃. Temperatures below 60℃ affect aluminum formation, leading to difficulties in subsequent liquid-solid separation; temperatures above 65℃ cause the exothermic reaction during the hydrogen peroxide oxidation of iron, raising the system temperature above 70℃ and reducing hydrogen peroxide utilization. Compared to traditional processes (85-95℃), the reaction temperature is reduced by 20-35℃, effectively saving energy and significantly improving the operating environment. Subsequently, the acid generated in situ during the hydrolysis of ferric iron is used to gently acid-wash the previously generated aluminum hydroxide precipitate, effectively desorbing and recovering the nickel and cobalt ions physically entrained by the aluminum hydroxide, significantly reducing the loss of valuable metals. Meanwhile, the pre-formed flaky aluminum slag acts as a seed crystal, inducing subsequent iron precipitation to form a coarse, porous granular structure, significantly improving the sedimentation and filtration performance of the slurry. Furthermore, the aluminum ions recovered through in-situ acid washing are used in the silicon removal process to precipitate silicon, achieving efficient cascade utilization of materials within the system and effectively reducing the consumption of auxiliary materials in this process.

[0020] In some preferred embodiments, in step S3, the iron precipitation is carried out until the ferrous concentration is ≤0.1g / L and the pH drops to 3.0~3.5.

[0021] In some embodiments, in step S1, the phosphorus-iron liquid is selected from the phosphorus-iron mother liquor or its diluted solution produced by the process of preparing ferric phosphate from nickel iron, the phosphorus content in the phosphorus-iron liquid is 0.5~0.8 g / L, and the liquid-to-solid ratio of the phosphorus-iron liquid to the crude nickel-cobalt hydroxide is (1~3) m. 3 :1t; And / or, in step S2, the liquid-to-solid ratio of the leaching agent to the primary leaching residue is (2~3) m. 3 :1t; And / or, in step S4, the temperature rise is raised to 60~85℃, and the silicon removal time is 1~4h.

[0022] The phosphorus content in the phosphorus-iron liquid selected in this invention needs to be controlled within a certain range. If the content is too low, the scandium precipitation rate will be less than 90%. If the content is too high, the aluminum precipitation will increase, affecting the grade of the scandium slag.

[0023] In some embodiments, in step S5, the mass ratio of the desiliconized slag to the concentrated sulfuric acid is (0.5~2):1, and the liquid-to-solid ratio is (2~3) m. 3 Add 1t of water; the reaction time is 30~60min.

[0024] According to a second aspect of the present invention, the application of the method described in the first aspect in mineral resource regeneration is proposed. The present invention can perform stepwise precipitation of impurities in the nickel-cobalt hydroxide intermediate obtained from laterite nickel ore smelting, effectively realizing the comprehensive utilization of resources.

[0025] According to one embodiment of the present invention, at least the following beneficial effects are achieved: This invention utilizes the surplus phosphorus-containing iron mother liquor produced during the process of preparing iron phosphate from nickel-iron, using the phosphorus it contains as a precipitant to achieve highly efficient and selective recovery of scandium. This fully leverages the resource value of phosphorus in the iron phosphate mother liquor and achieves the cascade utilization of sulfuric acid and ferrous iron in the mother liquor—sulfuric acid can be used as a leaching agent in the leaching process, ferrous iron as a reducing agent, and silicon is simultaneously removed in the silicon removal process. Finally, nickel is efficiently recovered as a nickel-cobalt-containing solution. This process can achieve a scandium precipitation rate of over 90%, with the scandium grade in the resulting scandium slag enriched to 10%–20%. While achieving significant enrichment of scandium, it effectively suppresses the co-precipitation loss of valuable main metals such as nickel and cobalt, significantly improving the overall recovery efficiency. Attached Figure Description

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a process flow diagram of Embodiment 1 of the present invention; Figure 2 This is a SEM image of scandium slag obtained in Example 1 of the present invention, magnified 50,000 times. Figure 3 This is a 10,000x magnified SEM image of the scandium residue obtained in Example 1 of the present invention; Figure 4 This is a SEM image of the scandium slag obtained in Comparative Example 2 of this invention, magnified 50,000 times. Figure 5 This is a 10,000x magnified SEM image of the scandium residue obtained in Comparative Example 2 of this invention. Figure 6 This is a SEM image of the silicon dioxide obtained in Example 1 of the present invention; Figure 7 This is an EDS image of the silicon dioxide obtained in Example 1 of the present invention; Figure 8 Here is a SEM image of the iron-aluminum slag obtained in Example 1 of this invention; Figure 9 The image shows the XRD pattern of the iron-aluminum slag obtained in Example 1 of this invention. Figure 10 This is a SEM image of the iron-aluminum slag obtained in Comparative Example 4 of this invention. Figure 11 The image shows the XRD pattern of the iron-aluminum slag obtained in Comparative Example 4 of this invention. Detailed Implementation

[0027] The following will describe the concept and technical effects of the present invention clearly and completely with reference to the embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0028] Experimental methods not specifically described in the following examples were performed according to conventional methods and conditions. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following examples or comparative examples can be obtained from conventional commercial sources or by existing known methods. The nickel-cobalt hydroxide is obtained from laterite nickel ore smelting, and its main components are as follows (in weight percentage): Ni: 15%~22%, Co: 1%~3%, Mn: 2%~4%, Cu: 0.05%~0.24%, Fe: 0.1%~0.3%, Al: 0.05%~0.18%, Si: 0.04%~0.24%, Sc: 0.01%~0.06%; the iron-phosphorus mother liquor contains the following components: Ni: 20g / L~30g / L, P: 3g / L~4g / L, Fe 2+ :1g / L~1.5g / L, Si:0.1g / L-0.15g / L, Cu:0.2mg / L~0.5mg / L, Al:0.1mg / L, H2SO4:60g / L~70g / L; the particle size of the atomized iron powder is 40~80 mesh.

[0029] Example 1 A method for separating impurities from nickel-cobalt hydroxide through stepwise precipitation, such as Figure 1 As shown, the specific steps include the following: (1) Single leaching: 18 tons of nickel-cobalt hydroxide, the mother liquor of ferrophosphate produced by the nickel-iron process, and water are leached at a liquid-to-solid ratio of 3m 3 1 ton of pulp was prepared (phosphorus iron mother liquor to water volume ratio of 1:4), stirring was started, sulfuric acid was added to adjust the pH to 0.5, and the reaction was carried out for 0.5 hours; then nickel cobalt hydroxide was added to adjust the solution pH to 5.8. Solid-liquid separation yielded primary leaching solution and primary leaching residue. The primary leaching solution entered the desiliconization process, and the primary leaching residue was reused in the pulping operation of the primary leaching process. After repeating this process 3 times to enrich impurities, it entered the secondary leaching process.

[0030] (2) Secondary leaching: The primary leaching residue after impurity enrichment is mixed with water at a liquid-to-solid ratio of 2m. 31t of mixed pulp is prepared, stirring is started, sulfuric acid is added to adjust the pH to about 0.5, and hydrogen peroxide with a mass percentage concentration of 27% is added until the leachate is clear. At this time, the pH of the solution rises to about 1.0. Solid-liquid separation is performed to obtain secondary leachate and secondary leachate residue. The secondary leachate enters the copper removal process, and the secondary leachate residue is discarded after washing with water.

[0031] (3) Copper removal: Detect the copper concentration in the secondary leaching solution obtained in step (2), add atomized iron powder at 0.85 times the copper content, stir and react for 1 hour to remove copper to below 0.1 g / L, and separate the solid and liquid to obtain copper-removed liquid and sponge copper. The copper-removed liquid enters the scandium removal process, and the sponge copper is washed with water and used as a by-product.

[0032] (4) Scandium removal: The scandium concentration (Sc: 211 mg / L) of the copper-removed solution obtained in step (3) was measured. A 15% sodium carbonate solution was added and used to adjust the pH of the reaction endpoint to 2.5. The reaction temperature was 20℃, and the reaction was stirred for 60 min. The solid and liquid were separated to obtain the scandium-removed solution (Sc: 11.56 mg / L) and scandium residue. The scandium-removed solution entered the iron and aluminum removal process. The scandium residue was washed with water and used as a by-product. Its SEM image is shown below. Figure 2 , Figure 3 As shown, ScPO4 exhibits a regular, dispersed, and relatively coarse morphology, indicating that ScPO4 in the absence of Fe 3+ Crystallization is good under interference.

[0033] (5) Removal of iron and aluminum: The scandium-removed solution obtained in (4) is heated to 60°C and subjected to a 1.5m... 3 Add 15% sodium carbonate solution at a rate of / h to adjust the pH to 4.4 at the final reaction point (Fe: 1.96 g / L, Al: 168 mg / L in the liquid phase), then proceed at 2m 3 At a rate of / h, 27% hydrogen peroxide was added to oxidize ferrous iron until the ferrous iron concentration was ≤0.1g / L (Fe: 14.8mg / L, Al: 545mg / L). At this point, the pH of the solution dropped to around 3.4. Solid-liquid separation yielded a liquid after iron and aluminum removal and iron-aluminum slag. The liquid after iron and aluminum removal entered the desiliconization process. The iron-aluminum slag (Ni: 1.73%, Co: 0.26%) was acid-washed with dilute sulfuric acid and then discarded as waste slag (Ni: 0.79%, Co: 0.10%). Its SEM and XRD patterns are shown below. Figure 8 , Figure 9 As shown in the figure, this invention first performs aluminum precipitation to obtain sheet-like aluminum hydroxide as seed crystals, which induces the subsequent growth of iron hydroxide on its surface. SEM images show that a loose sheet-like structure is formed, which significantly improves filtration performance. XRD images show high crystallinity and a single phase, that is, the separate precipitation of iron and aluminum avoids the co-precipitation of colloidal substances generated by the simultaneous hydrolysis of iron and aluminum, thus reducing the entrainment loss of valuable metals.

[0034] (6) Desiliconization: The leaching solution obtained in step (1) and the desiliconized solution obtained in step (5) are mixed and heated to 70°C. A 15% soda ash solution is added to adjust the pH to 6.3 for desiliconization. After stirring and reacting for 4 hours, a nickel-cobalt-manganese sulfate solution and desiliconized slag are obtained (the yields of nickel, cobalt and manganese are all above 99%). The desiliconized slag is then put into the carbonization process.

[0035] (7) Carbonization treatment of silicon slag: Add concentrated sulfuric acid with a mass percentage concentration of 98% directly to the silicon slag obtained in step (6) and stir to make a slurry (the mass ratio of silicon slag to concentrated sulfuric acid is 1:1), and then make a liquid-solid ratio of 3m 3 After adding 1 ton of water and stirring for 30 minutes, solid-liquid separation yielded silica and an acid leaching solution containing nickel and aluminum. The acid leaching solution was reused in the pulping process for secondary leaching. The silica was washed with water and treated as a byproduct. The wash water could be combined with the acid leaching solution for further treatment. The SEM and EDS images are shown below. Figure 6 , Figure 7 As shown, by Figure 7 It can be seen that the silicon slag obtained by this invention is mainly silicon dioxide (SiO2) or hydrated silicon dioxide, and the EDS analysis data are as follows:

[0036] Example 2 A method for separating impurities from nickel cobalt hydroxide through a stepwise precipitation process includes the following specific steps: (1) Single leaching: 18 tons of nickel-cobalt hydroxide, the mother liquor of ferrophosphate produced by the nickel-iron process, and water are leached at a liquid-to-solid ratio of 2m 3 1 ton of pulp was prepared (the volume ratio of phosphorus iron mother liquor to water was 1:4). Stirring was started, sulfuric acid was added to adjust the pH to 0.5, and the reaction was carried out for 1 hour. Then, nickel cobalt hydroxide was added to adjust the pH of the solution to 6.0. Solid-liquid separation yielded primary leaching solution and primary leaching residue. The primary leaching solution entered the desiliconization process, and the primary leaching residue was returned to the primary leaching process to enrich impurities three times before entering the secondary leaching process.

[0037] (2) Secondary leaching: The primary leaching residue after impurity enrichment is mixed with water at a liquid-to-solid ratio of 3m. 3 1t of mixed pulp is prepared, stirring is started, sulfuric acid is added to adjust the pH to about 1.0, and hydrogen peroxide with a mass percentage concentration of 27% is added until the leachate is clear. At this time, the pH of the solution rises to about 1.5. Solid-liquid separation is performed to obtain secondary leachate and secondary leachate residue. The secondary leachate enters the copper removal process, and the secondary leachate residue is discarded after water washing.

[0038] (3) Copper removal: Detect the copper concentration in the secondary leaching solution obtained in step (2), add atomized iron powder at 0.9 times the copper content, stir and react for 1 hour to remove copper to below 0.1 g / L, and separate the solid and liquid to obtain copper-removed liquid and sponge copper. The copper-removed liquid enters the scandium removal process, and the sponge copper is washed with water and used as a by-product.

[0039] (4) Scandium removal: The scandium concentration (Sc: 224 mg / L) of the copper-removed liquid obtained in step (3) is detected. A 10% soda ash solution is added and used to adjust the pH of the reaction endpoint to 3.5. The reaction temperature is 50℃ and the reaction is stirred for 40 min. The solid and liquid are separated to obtain the scandium-removed liquid (Sc: 1.48 mg / L) and the scandium-removed slag. The scandium-removed liquid enters the iron and aluminum removal process. The scandium slag is washed with water and used as a by-product.

[0040] (5) Removal of iron and aluminum: The scandium-removed solution obtained in (4) is heated to 65°C and subjected to a 3m... 3 Add 10% sodium carbonate solution at a rate of / h to adjust the pH to 4.1 at the final reaction point (Fe: 1.61 g / L, Al: 273 mg / L in the liquid phase), then proceed at 1m 3 At a rate of / h, 27% hydrogen peroxide is added to oxidize ferrous iron until the ferrous iron concentration is ≤0.1g / L (Fe: 22.3mg / L, Al: 573mg / L). At this point, the pH of the solution drops to about 3.1. Solid-liquid separation is performed to obtain the liquid after iron and aluminum removal and iron-aluminum slag. The liquid after iron and aluminum removal enters the desiliconization process. The iron-aluminum slag (Ni: 1.54%, Co: 0.22%) is acid washed with dilute sulfuric acid and then discarded as waste slag (Ni: 0.71%, Co: 0.09%).

[0041] (6) Desiliconization: The leaching solution obtained in step (1) and the desiliconized solution obtained in step (5) are mixed and heated to 60°C. A 10% soda ash solution is added to adjust the pH to 6.5 for desiliconization. After stirring and reacting for 1 hour, a nickel-cobalt-manganese sulfate solution and desiliconized slag are obtained (the yields of nickel, cobalt and manganese are all above 99%). The desiliconized slag is then put into the carbonization process.

[0042] (7) Carbonization treatment of silicon slag: Add concentrated sulfuric acid with a mass percentage concentration of 98% directly to the silicon slag obtained in step (6) and stir to make a slurry (the mass ratio of silicon slag to concentrated sulfuric acid is 1:2), and then make a liquid-solid ratio of 2m 3 After adding 1t of water and stirring for 30 minutes, the solid and liquid are separated to obtain silica and an acid leaching solution containing nickel and aluminum. The acid leaching solution is reused in the pulping operation of the secondary leaching. The silica is washed with water and used as a by-product. The wash water can be combined with the acid leaching solution for treatment.

[0043] Example 3 A method for separating impurities from nickel cobalt hydroxide through a stepwise precipitation process includes the following specific steps: (1) Single leaching: 18 tons of nickel-cobalt hydroxide, the mother liquor of ferrophosphate produced by the nickel-iron process, and water are leached at a liquid-to-solid ratio of 1 m 31 t of pulp was prepared (the volume ratio of phosphorus iron mother liquor to water was 1:4), stirring was started, sulfuric acid was added to adjust the pH to 0.8, and the reaction was carried out for 0.75 h; then nickel cobalt hydroxide was added to adjust the pH of the solution to 6.3. Solid-liquid separation yielded primary leaching solution and primary leaching residue. The primary leaching solution entered the desiliconization process, and the primary leaching residue was returned to the primary leaching process to enrich impurities three times before entering the secondary leaching process.

[0044] (2) Secondary leaching: The primary leaching residue after impurity enrichment is mixed with water at a liquid-to-solid ratio of 2m. 3 1t of mixed pulp is prepared, stirring is started, sulfuric acid is added to adjust the pH to about 0.9, and hydrogen peroxide with a mass percentage concentration of 27% is added until the leachate is clear. At this time, the pH of the solution rises to about 1.5. Solid-liquid separation is performed to obtain secondary leachate and secondary leachate residue. The secondary leachate enters the copper removal process, and the secondary leachate residue is discarded after washing with water.

[0045] (3) Copper removal: Detect the copper concentration in the secondary leaching solution obtained in step (2), add atomized iron powder at 0.9 times the copper content, stir and react for 1 hour to remove copper to below 0.1 g / L, and separate the solid and liquid to obtain copper-removed liquid and sponge copper. The copper-removed liquid enters the scandium removal process, and the sponge copper is washed with water and used as a by-product.

[0046] (4) Scandium removal: The scandium concentration (Sc: 142 mg / L) of the copper-removed liquid obtained in step (3) is detected. A 12% sodium carbonate solution is added and used to adjust the pH of the reaction endpoint to 3. The reaction temperature is 60℃ and the reaction is stirred for 20 min. The solid and liquid are separated to obtain the scandium-removed liquid (Sc: 5.12 mg / L) and scandium residue. The scandium-removed liquid enters the iron and aluminum removal process, and the scandium residue is washed with water and used as a by-product.

[0047] (5) Removal of iron and aluminum: The scandium-removed solution obtained in (4) is heated to 63°C and subjected to a 2.5m... 3 Add a 12% (w / h) sodium carbonate solution to adjust the final pH to 4.4 (Fe: 1.78 g / L, Al: 176 mg / L in the liquid phase), then add sodium carbonate solution at a rate of 1.5 m / h. 3 At a rate of / h, 27% hydrogen peroxide is added to oxidize ferrous iron until the ferrous iron concentration is ≤0.1g / L (Fe: 32.6mg / L, Al: 509mg / L). At this point, the pH of the solution drops to about 3.5. Solid-liquid separation is performed to obtain the liquid after iron and aluminum removal and iron-aluminum slag. The liquid after iron and aluminum removal enters the desiliconization process. The iron-aluminum slag (Ni: 1.68%, Co: 0.17%) is acid washed with dilute sulfuric acid and then discarded as waste slag (Ni: 0.76%, Co: 0.11%).

[0048] (6) Desiliconization: The leaching solution obtained in step (1) and the desiliconized solution obtained in step (5) are mixed and heated to 85°C. A 12% soda ash solution is added to adjust the pH to 6.3 for desiliconization. After stirring and reacting for 3 hours, a nickel-cobalt-manganese sulfate solution and desiliconized slag are obtained (the yields of nickel, cobalt and manganese are all above 99%). The desiliconized slag is then put into the carbonization process.

[0049] (7) Carbonization treatment of silicon slag: Add concentrated sulfuric acid with a mass percentage concentration of 98% directly to the silicon slag obtained in step (6) and stir to make a slurry (the mass ratio of silicon slag to concentrated sulfuric acid is 2:1), and then make a liquid-solid ratio of 3m 3 After adding 1 t of water, stir and react for 40 min. Solid-liquid separation yields silica and an acid leaching solution containing nickel and aluminum. The acid leaching solution is reused in the pulping operation of secondary leaching. Silica is washed with water and used as a by-product. The wash water can be combined with the acid leaching solution for treatment.

[0050] Example 4 A method for separating impurities from nickel cobalt hydroxide through a stepwise precipitation process includes the following specific steps: (1) Single leaching: 18 tons of nickel-cobalt hydroxide, the mother liquor of ferrophosphate produced by the nickel-iron process, and water are leached at a liquid-to-solid ratio of 3m 3 1 ton of pulp was prepared (the volume ratio of phosphorus iron mother liquor to water was 1:4). Stirring was started, sulfuric acid was added to adjust the pH to 0.5, and the reaction was carried out for 0.8 hours. Then, nickel cobalt hydroxide was added to adjust the pH of the solution to 6.5. Solid-liquid separation yielded primary leaching solution and primary leaching residue. The primary leaching solution entered the desiliconization process, and the primary leaching residue was returned to the primary leaching process to enrich impurities three times before entering the secondary leaching process.

[0051] (2) Secondary leaching: The primary leaching residue after impurity enrichment is mixed with water at a liquid-to-solid ratio of 3m. 3 1t of mixed pulp is prepared, stirring is started, sulfuric acid is added to adjust the pH to about 1.0, and hydrogen peroxide with a mass percentage concentration of 27% is added until the leachate is clear. At this time, the pH of the solution rises to about 1.5. Solid-liquid separation is performed to obtain secondary leachate and secondary leachate residue. The secondary leachate enters the copper removal process, and the secondary leachate residue is discarded after washing with water.

[0052] (3) Copper removal: Detect the copper concentration in the secondary leaching solution obtained in step (2), add atomized iron powder at 0.85 times the copper content, stir and react for 1 hour to remove copper to below 0.1 g / L, and separate the solid and liquid to obtain copper-removed liquid and sponge copper. The copper-removed liquid enters the scandium removal process, and the sponge copper is washed with water and used as a by-product.

[0053] (4) Scandium removal: The scandium concentration (Sc: 199 mg / L) of the copper-removed liquid obtained in step (3) is detected. A 12% soda ash solution is added and used to adjust the pH of the reaction endpoint to 3. The reaction temperature is 40℃ and the reaction is stirred for 30 min. The solid and liquid are separated to obtain the scandium-removed liquid (Sc: 6.54 mg / L) and the scandium-removed slag. The scandium-removed liquid enters the iron and aluminum removal process. The scandium slag is washed with water and used as a by-product.

[0054] (5) Removal of iron and aluminum: The scandium-removed solution obtained in (4) is heated to 65°C and sprayed with 2m 3 Add a 12% (w / h) sodium carbonate solution to adjust the final pH to 4.1 (Fe: 1.62 g / L, Al: 223 mg / L in the liquid phase), then add sodium carbonate solution at a rate of 1.2 m / h. 3 At a rate of / h, 27% hydrogen peroxide is added to oxidize ferrous iron until the ferrous iron concentration is ≤0.1g / L (Fe: 26.3mg / L, Al: 553mg / L). At this point, the pH of the solution drops to around 3.0. Solid-liquid separation yields a liquid after iron and aluminum removal and iron-aluminum slag. The liquid after iron and aluminum removal enters the desiliconization process, while the iron-aluminum slag (Ni: 1.55%, Co: 0.12%) is discarded after acid washing with dilute sulfuric acid (Ni: 0.68%, Co: 0.08%).

[0055] (6) Desiliconization: The leaching solution obtained in step (1) and the desiliconized solution obtained in step (5) are mixed and heated to 85°C. A 12% soda ash solution is added to adjust the pH to 6.5 for desiliconization. After stirring and reacting for 2 hours, a nickel-cobalt-manganese sulfate solution and desiliconized slag are obtained (the yields of nickel, cobalt and manganese are all above 99%). The desiliconized slag is then put into the carbonization process.

[0056] (7) Carbonization treatment of silicon slag: Add concentrated sulfuric acid with a mass percentage concentration of 98% directly to the silicon slag obtained in step (6) and stir to make a slurry (the mass ratio of silicon slag to concentrated sulfuric acid is 1:1), and then make a liquid-solid ratio of 3m 3 After adding 1 ton of water, stir and react for 50 minutes. Solid-liquid separation yields silica and an acid leaching solution containing nickel and aluminum. The acid leaching solution is reused in the pulping operation of secondary leaching. Silica is washed with water and used as a by-product. The wash water can be combined with the acid leaching solution for treatment.

[0057] Comparative Example 1 Except for adjusting the pH of the reaction endpoint to 4 using a 12% sodium carbonate solution in step (4), this comparative example is the same as Example 1.

[0058] Comparative Example 2 This comparative example is identical to Example 1 except that steps (3) and (4) are reversed, i.e., scandium removal is performed first, followed by copper removal. The details are as follows: (3) Scandium removal: Add and adjust the pH of the reaction endpoint to 3 using a 12% (w / w) sodium carbonate solution to the secondary leaching solution. The reaction temperature is 40°C, and the reaction is stirred for 30 min. Solid-liquid separation is performed to obtain the scandium-removed liquid and the scandium-removed residue. The scandium residue is washed with water and used as a by-product. Its SEM image is shown below. Figure 4 , Figure 5 As shown, it exhibits a flocculent, aggregated, and amorphous morphology, indicating that Fe... 3+ The presence of scandium leads to co-precipitation and colloid formation, which seriously affects the purity and filtration performance of scandium residue. (4) Copper removal: The copper concentration in the scandium removal solution is detected. Atomized iron powder is added at 0.85 times the copper content. The mixture is stirred and reacted for 1 hour to remove copper down to below 0.1 g / L. The solid and liquid are separated to obtain copper removal solution and sponge copper. Copper removal solution enters the iron and aluminum removal process. Sponge copper is washed with water and used as a by-product.

[0059] Comparative Example 3 The only difference between this comparative example and Example 1 is that the atomized iron powder used in step (3) is replaced with reduced iron powder of 40-80 mesh, and the copper content is reduced to below 0.1 g / L by adding 1.1 times the amount of copper.

[0060] Comparative Example 4 Except for step (5), where hydrogen peroxide is added first to oxidize ferrous iron, and then sodium carbonate solution is used to adjust the ferrous oxide content, this comparative example is identical to Example 2. The SEM and XRD images of the resulting iron-aluminum slag are shown below. Figure 10 , Figure 11 As shown, the XRD pattern indicates that the iron-aluminum slag has low crystallinity, and the SEM pattern shows that it has formed amorphous colloids with severe agglomeration, which will lead to filtration difficulties and easy adsorption of valuable metal ions, resulting in losses.

[0061] Comparative Example 5 Except for step (5), in which hydrogen peroxide is added first to oxidize ferrous iron, and then the ferrous oxide solution is used to adjust the ferrous oxide value, the comparative example is the same as that in Example 1.

[0062] Comparative Example 6 Except for step (7), in which water is added first to make a slurry and then sulfuric acid is added in a 2:1 ratio, this comparative example is the same as Example 3, as follows: (7) Silicon slag carbonization treatment: The silicon slag obtained in step (6) is subjected to a liquid-to-solid ratio of 3m 3 Add 1 ton of water, then add concentrated sulfuric acid with a mass percentage concentration of 98% and stir to make pulp (the mass ratio of silicon slag to concentrated sulfuric acid is 2:1). Stir and react for 40 minutes. Separate the solid and liquid to obtain silicon dioxide and acid leaching solution containing nickel and aluminum. Wash the silicon dioxide with water as a by-product. Combine the wash water and acid leaching solution and reuse them for the pulping operation of secondary leaching.

[0063] Comparative Example 7 Except for step (5), in which the pH of the solution after scandium removal is adjusted to 4.6 at the reaction endpoint, this comparative example is the same as Example 4.

[0064] Test case 10g of scandium residue from each example and comparative example was dried in an oven at 100℃ for 4 hours, digested with aqua regia and diluted, and detected by ICP (Icap7200 inductively coupled plasma atomic emission spectrometer). The results are shown in Table 1. Table 1 Scandium Slag Detection Data

[0065] As shown in Table 1, in Comparative Example 1, if the pH at the reaction endpoint is too high, the aluminum content in the resulting scandium slag is higher than the scandium content, leading to a significant decrease in scandium selectivity. Furthermore, Comparative Example 2 shows that if the process sequence of "scandium removal first, then copper removal" is adopted, the iron in the secondary leaching solution is ferric iron (Fe3+), resulting in a higher iron content in the resulting scandium slag and affecting the scandium enrichment effect. This indicates that the scandium removal process requires pre-reduction treatment of ferric iron. This invention places the copper removal process beforehand, ensuring that the iron in the solution entering the scandium removal process remains in the divalent state. Combined with precise control of the pH at the reaction endpoint, this effectively achieves highly efficient and selective recovery of scandium.

[0066] The iron-aluminum slag produced in each embodiment and comparative example was tested, and the results are shown in Table 2: Table 2. Detection data of iron-aluminum slag

[0067] As can be seen from Comparative Examples 4 and 5 in Table 2, this invention, by optimizing the process to "aluminum precipitation followed by iron oxidation precipitation," successfully solves the problem of nickel being easily carried away and lost in traditional processes, significantly reducing the loss rate of valuable metals. Meanwhile, as shown in Comparative Example 7, if the pH is too high during the iron and aluminum removal process, nickel and cobalt precipitation will significantly increase, resulting in a higher content of nickel and cobalt in the iron and aluminum slag, leading to losses.

[0068] The silica produced in each embodiment and comparative example was tested, and the results are shown in Table 3: Table 3 Silica Detection Data

[0069] As shown in Table 3, the present invention utilizes a carbonization process with strong acid to rapidly dissolve nickel, cobalt, manganese, and aluminum in silicon slag, yielding pure silica slag. In contrast, Comparative Example 6, which employs a liquid-phase acidification leaching process followed by slurry preparation, resulted in a significant increase in the residual amounts of nickel, cobalt, manganese, and aluminum in its silicon slag. This fully demonstrates the significant advantages and high efficiency of the carbonization process of the present invention in removing various metallic impurities from silicon slag.

[0070] The nickel cobalt manganese sulfate solutions produced in each example and comparative example were tested, and the results are shown in Table 4: Table 4 Detection data of nickel cobalt manganese sulfate solution

[0071] As shown in Table 4, the "aluminum precipitation followed by iron oxide precipitation" process of this invention allows some aluminum to be dissolved back into the silicon removal process to synergistically precipitate silicon impurities. The silicon concentration in the resulting nickel sulfate solution is consistently below 5 mg / L, while the silicon concentration in the nickel sulfate solutions obtained using the traditional iron and aluminum removal processes in Comparative Examples 4 and 5 is 15-20 mg / L. These results demonstrate that the "aluminum precipitation followed by iron oxide precipitation" process of this invention not only reduces the loss of nickel and cobalt metals but also synergistically reduces the silicon impurity content in the nickel sulfate solution, significantly improving product quality and laying a solid foundation for the subsequent preparation of high-purity nickel salt products.

[0072] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for separating impurities from crude nickel-cobalt hydroxide, characterized in that, Includes the following steps: S1: Mix crude nickel-cobalt hydroxide with ferric phosphorus solution to form a slurry, adjust the pH to 0.5~1.0 to carry out the reaction, and then add a pH adjuster to make the pH 5.4~6.

5. After solid-liquid separation, a primary leaching solution and a primary leaching residue are obtained. S2: Mix the primary leaching residue with the leaching agent, adjust the pH to 0.5~1.0 for leaching, then perform solid-liquid separation, and sequentially remove copper and scandium from the obtained secondary leaching solution to obtain the first impurity-removed solution; S3: After heating the first purified liquid, adjust the pH to 4.1~4.4 to precipitate aluminum, then add an oxidant to precipitate iron. After solid-liquid separation, take the liquid phase to obtain the second purified liquid. S4: Mix the first leaching solution from step S1 with the second impurity-removed solution from step S3, raise the temperature, adjust the pH to 6.3~6.5 to remove silicon, and then separate the solid and liquid to obtain a nickel-cobalt-containing solution and silicon-removed slag.

2. The method according to claim 1, characterized in that, Before step S2, the process also includes: reusing the primary leaching residue for the pulping operation in step S1, and repeating step S1 two to three times.

3. The method according to claim 1, characterized in that, Also includes: S5: Take the desiliconized slag from step S4, mix it with concentrated sulfuric acid to make a slurry, add water to continue the reaction, and after solid-liquid separation, obtain silicon dioxide and nickel-aluminum acid leaching solution. The nickel-aluminum acid leaching solution is reused for the leaching operation in step S2.

4. The method according to claim 1, characterized in that, In step S2, before performing the solid-liquid separation, hydrogen peroxide is added until the liquid phase is clear.

5. The method according to claim 1, characterized in that, In step S1, the pH adjuster is selected from crude nickel cobalt hydroxide; and / or, in step S2, the leaching agent includes at least one of water or sulfuric acid; and / or, in step S3, the oxidant is selected from hydrogen peroxide.

6. The method according to claim 1, characterized in that, In step S2, the copper removal process includes: mixing and reacting the secondary leaching solution with atomized iron powder, and then separating the solid and liquid to obtain copper-removed liquid and sponge copper. The scandium removal process includes: adjusting the pH of the copper-removed solution to 2.5-3.5 for reaction, and then performing solid-liquid separation to obtain the first impurity-removed solution and scandium residue.

7. The method according to claim 1, characterized in that, In step S3, the temperature rise is to 60~65℃; and / or the oxidant addition rate is 1~2 m. 3 / h.

8. The method according to claim 1, characterized in that, In step S1, the phosphorus-iron liquid is selected from the phosphorus-iron mother liquor or its diluted solution produced by the process of preparing ferric phosphate from nickel iron. The phosphorus content in the phosphorus-iron liquid is 0.5~0.8 g / L, and the liquid-to-solid ratio of the phosphorus-iron liquid to the crude nickel-cobalt hydroxide is (1~3) m. 3 :1t; And / or, in step S2, the liquid-to-solid ratio of the leaching agent to the primary leaching residue is (2~3) m. 3 :1t; And / or, in step S4, the temperature rise is raised to 60~85℃, and the silicon removal time is 1~4h.

9. The method according to claim 3, characterized in that, In step S5, the mass ratio of the desiliconized slag to the concentrated sulfuric acid is (0.5~2):1, and the liquid-to-solid ratio is (2~3). 3 Add 1t of water; the reaction time is 30~60min.

10. The application of the method according to any one of claims 1-9 in mineral resource regeneration.

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