A method for comprehensive recovery of nickel, cobalt, manganese and magnesium from laterite nickel ore

Abstract

This invention relates to the field of hydrometallurgical technology and discloses a method for the comprehensive recovery of nickel, cobalt, manganese, and magnesium from laterite nickel ore. It aims to solve the technical problems of nickel-cobalt-manganese co-precipitation and the lack of comprehensive utilization of magnesium resources in existing high-pressure leaching (MHP) processes for laterite nickel ore. The process uses laterite nickel ore as raw material and sequentially undergoes leaching, countercurrent washing, two-stage iron and aluminum removal, manganese and cobalt cascade oxidation precipitation recovery, nickel precipitation, magnesium precipitation, and tailings recycling and tailings neutralization. Manganese and cobalt recovery can be achieved through either stepwise precipitation or combined precipitation. Manganese and cobalt are separated and recovered by controlling oxidation conditions and pH value. High-purity nickel-only MHP products are then prepared through nickel precipitation. Finally, magnesium is recovered, and tailings are reused while tailings are discharged in compliance with standards. This invention achieves stepwise separation and high-value recovery of nickel, cobalt, manganese, and magnesium at the smelting stage, shortening subsequent refining processes, saving reagent costs, improving resource utilization and environmental friendliness, and meeting the raw material supply needs of the EV battery industry chain.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical technology, and more specifically, to a method for the comprehensive recovery of nickel, cobalt, manganese and magnesium from laterite nickel ore. Background Technology

[0002] With the rapid development of the global new energy vehicle and power battery industry, the market demand for high-nickel ternary cathode materials continues to rise. As core metal raw materials, the stable supply and low-cost preparation of nickel and cobalt have become key factors restricting the development of the industry chain. Laterite nickel ore, as the world's largest and most widely distributed type of nickel resource (accounting for more than 50% of global nickel resources), has long been unable to be efficiently utilized due to its low grade and high energy consumption of traditional pyrometallurgical processes. In recent years, high-pressure acid leaching (HPAL) hydrometallurgical technology has matured, selectively leaching nickel and cobalt from laterite nickel ore under high temperature and high pressure conditions. It has advantages such as high recovery rate, strong raw material adaptability, and environmental friendliness, and has become the mainstream process route for nickel and cobalt raw material supply in the EV battery industry chain.

[0003] Currently, the mainstream high-pressure leaching process in industry mainly includes core steps such as leaching, pre-neutralization, two-stage iron and aluminum removal, two-stage nickel and cobalt precipitation, and tailings neutralization, ultimately producing nickel-cobalt hydroxide intermediate (MHP). This process has been applied on a large scale by major enterprises both domestically and internationally. It is technically mature and reliable, has a large capacity, and operates stably. It can effectively process low-grade limonite-type laterite nickel ore, achieving efficient enrichment and recovery of nickel and cobalt.

[0004] However, the existing high-pressure leaching-coprecipitation process for preparing MHP still has significant drawbacks, which severely restrict resource utilization and economic efficiency, specifically in the following two aspects: (1) MHP products have complex metal compositions, resulting in high costs and long processes for subsequent refining and separation. The current process uses co-precipitation to recover nickel and cobalt. During the precipitation process, not only do more than 80% of nickel and cobalt enter the MHP, but also about 15% of manganese and a small amount of magnesium precipitate into the product, resulting in the coexistence of nickel, cobalt and manganese in the MHP. In order to obtain battery-grade nickel sulfate and cobalt sulfate solutions, the subsequent refining process must be equipped with a complex extraction and separation system, including multi-stage extraction to remove manganese, nickel and cobalt extraction and separation, back-extraction, purification and other links. The process is lengthy, the equipment investment is large, and a large amount of acid, alkali and extractant are consumed, resulting in high production costs and serious waste of resources.

[0005] (2) Magnesium in the system is not effectively separated and comprehensively utilized, resulting in the loss of resource value and affecting product quality. The magnesium content in laterite nickel ore is generally high (especially serpentine type ore). During the leaching process, a large amount of magnesium enters the solution, but the existing process only treats magnesium as an impurity in the tailings and discharges it with the waste residue in the process, without realizing the recovery and productization of magnesium. On the one hand, the continuous accumulation of magnesium in the solution will affect the nickel-cobalt precipitation process and the purity of MHP products; on the other hand, magnesium is a metal element with high economic value, and its non-utilization causes resource waste and increases the pressure on tailings treatment and environmental protection.

[0006] In summary, while the existing high-pressure leaching process for preparing MHP from laterite nickel ore has been industrialized, it suffers from two major drawbacks: high refining and separation costs due to nickel-cobalt-manganese co-precipitation and the lack of comprehensive utilization of magnesium resources. These issues hinder the green, efficient, and high-value development of laterite nickel ore hydrometallurgical technology. Therefore, developing a new process that achieves selective and efficient precipitation of nickel and cobalt, stepwise recovery of manganese and magnesium, a shorter process, lower cost, and higher resource utilization is of significant practical importance for promoting the upgrading of raw material supply and comprehensive resource utilization in the EV battery industry chain. Summary of the Invention

[0007] In view of the above problems, the purpose of this invention is to provide a method for the comprehensive recovery of nickel, cobalt, manganese and magnesium from laterite nickel ore. This method solves the technical problems of existing high-pressure acid leaching processes for laterite nickel ore, which all use simultaneous co-precipitation of nickel, cobalt and manganese to produce MHP. Manganese, cobalt and nickel precipitate together, resulting in high product impurities, long subsequent separation processes, and the failure to recover magnesium, which puts great pressure on the environment. The method adopts a stepwise precipitation of manganese, cobalt, nickel and magnesium, realizing the separation of each metal from the smelting end, completely avoiding a series of drawbacks caused by co-precipitation, and achieving efficient separation and high-value utilization of nickel, cobalt, manganese and magnesium in laterite nickel ore.

[0008] This invention provides a method for the comprehensive recovery of nickel, cobalt, manganese, and magnesium from laterite nickel ore, comprising: S1: Acid leaching of laterite nickel ore to obtain leaching slurry; S2: The leaching slurry is countercurrently washed, and after washing, liquid-solid separation is performed to obtain the washed liquid and leaching residue, and the leaching residue is sent to the tailings neutralization process. S3: The washing liquid is subjected to a two-stage iron and aluminum removal treatment using limestone to obtain iron and aluminum removed liquid and iron and aluminum slag. During the iron and aluminum removal process, compressed air is introduced to oxidize ferrous iron. S4: The iron and aluminum removal liquid is subjected to manganese and cobalt recovery by oxidation precipitation method to obtain manganese product, cobalt product and manganese and cobalt precipitated liquid; S5: Add a precipitant to the manganese-cobalt precipitate solution to perform nickel precipitation treatment, and obtain nickel hydroxide product and nickel precipitate solution; S6: Add the precipitant to the nickel precipitation solution to perform magnesium precipitation treatment, and obtain magnesium product and magnesium precipitation solution; S7: A portion of the magnesium precipitation solution is returned to the washing process for recycling, and the remaining portion of the magnesium precipitation solution is combined with the leaching residue and recycled in the tailings neutralization process.

[0009] Alternatively, in S1, the acid leaching method is either high-pressure acid leaching or normal-pressure acid leaching, with a leaching temperature of 90~280℃ and a leaching time of 0.5~8h. The laterite nickel ore is limonite-type laterite nickel ore, residual laterite nickel ore, or a mixture of the two in any proportion. The liquid-solid separation method is either thickener separation or filter press separation.

[0010] Alternatively, in S2, the washing method can be countercurrent washing with multi-stage thickeners in series, or washing on the filter press or during slurry processing.

[0011] Alternatively, in S3, the endpoint pH values ​​for the two iron and aluminum removal stages are 3.5 to 5.2, with the endpoint pH value for the first stage of iron and aluminum removal being 3.5 to 4.2 and the endpoint pH value for the second stage of iron and aluminum removal being 4.5 to 5.2.

[0012] Alternatively, in step S4, during the manganese and cobalt recovery process of the iron-aluminum-removed liquid using the oxidation precipitation method, stepwise oxidation precipitation or combined oxidation precipitation can be employed to recover manganese and cobalt from the iron-aluminum-removed liquid; wherein, The stepwise oxidation precipitation process is as follows: First, under pH conditions of 4.5~5.5, an oxidant and a neutralizing agent are added sequentially to the liquid after iron and aluminum removal to precipitate manganese. After the manganese precipitation reaction is completed, the slurry is filtered and washed to obtain a manganese filter cake, and the manganese filter cake is acid washed to remove impurities to obtain the manganese product. Then, under pH conditions of 5.0~6.0, oxidant and neutralizing agent are added sequentially to the manganese-removed liquid to precipitate cobalt. After the cobalt precipitation reaction is completed, the slurry is filtered and washed to obtain a cobalt filter cake, and the cobalt filter cake is acid washed to remove impurities to obtain the cobalt product. The combined oxidation precipitation process is as follows: under pH conditions of 5.0~6.0, oxidant and neutralizing agent are added sequentially to the liquid after iron and aluminum removal to simultaneously precipitate manganese and cobalt. After the precipitation reaction is completed, the slurry is filtered and washed to obtain manganese filter cake and cobalt filter cake respectively. The manganese filter cake and cobalt filter cake are then acid washed to remove impurities to obtain manganese product and cobalt product.

[0013] Alternatively, in S4, the oxidant is selected from one or more of oxygen-based substances, ozone-based substances, a mixture of oxygen and sulfur dioxide in any proportion, persulfate, hydrogen peroxide, nitrite, and perchlorate. The neutralizing agent is selected from one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, magnesium carbonate, magnesium bicarbonate, ammonium carbonate, ammonium bicarbonate, calcium oxide, magnesium oxide, sodium hydroxide, potassium hydroxide, ammonia, calcium hydroxide, magnesium hydroxide, calcium carbonate, and calcium bicarbonate, or one or more of limestone, magnesia powder, magnesite, dolomite, and marble.

[0014] Alternatively, in S4, during stepwise oxidation precipitation, the amount of oxidant added for manganese precipitation is 1.0 to 10.0 times the stoichiometric ratio of divalent manganese, and the amount of oxidant added for cobalt precipitation is 1.0 to 10.0 times the stoichiometric ratio of divalent cobalt. When oxidizing and precipitating, the amount of oxidant added is 1.0 to 10.0 times the stoichiometric ratio of divalent cobalt to divalent manganese in the chemical reaction.

[0015] Alternatively, in step S4, when acid washing the manganese filter cake and the cobalt filter cake, the acid washing solution-to-solid ratio is 2-10:1, and sulfuric acid is used to adjust the acid washing pH to 1.0-3.0.

[0016] Alternatively, in step S5, a precipitant is added to the liquid after manganese and cobalt precipitation to carry out a nickel precipitation reaction; wherein the nickel precipitation conditions are: pH value of 7.0~9.0, precipitation temperature of room temperature~100℃, and reaction time of 0.5~8h. After the precipitation reaction is completed, the slurry is subjected to liquid-solid separation to obtain a bottom stream and a supernatant containing MHP solids. The separated underflow is washed to obtain the nickel hydroxide product; wherein, the amount of washing agent used in the washing process is 0.01~100% of the solid amount of MHP, the washing temperature is room temperature~100℃, and the washing time is 0.5~8h.

[0017] Alternatively, in S5, the precipitant may be selected from one or more of the following: sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, magnesium carbonate, magnesium bicarbonate, ammonium carbonate, ammonium bicarbonate, calcium oxide, magnesium oxide, sodium hydroxide, potassium hydroxide, ammonia, calcium hydroxide, magnesium hydroxide, calcium carbonate, and calcium bicarbonate.

[0018] Alternatively, in S5, the washing process may employ one or a combination of weak acid washing, alkaline washing, and nickel-cobalt solution washing; among which, The acid solution used for the weak acid washing is selected from one or more of sulfuric acid, hydrochloric acid, nitric acid, carbonic acid, and organic acids; The alkaline solution used for washing is selected from one or more of sodium hydroxide, potassium hydroxide, ammonia, and carbonates.

[0019] Alternatively, in S6, the magnesium precipitation conditions are: pH 9.0~11.0, precipitation temperature room temperature~100℃, and reaction time 0.5~8h.

[0020] As can be seen from the above technical solution, the present invention provides a method for the comprehensive recovery of nickel, cobalt, manganese, and magnesium from laterite nickel ore. This method employs a stepwise oxidation and precipitation process for manganese, cobalt, nickel, and magnesium. By controlling different pH levels and oxidation conditions, manganese, cobalt, nickel, and magnesium are precipitated sequentially, achieving stepwise separation of each metal. Compared with the traditional nickel-cobalt-manganese co-precipitation process, this method fundamentally solves the technical problems of high impurities, difficult subsequent purification, long process, and high cost associated with traditional MHP products, and has the following technical advantages: (1) By stepwise oxidation precipitation, manganese, cobalt and nickel are separated (or manganese and cobalt are combined and separated), the problem of nickel, cobalt and manganese co-precipitation into MHP products in traditional processes is avoided from the source. In the end, high-quality nickel hydroxide MHP products with almost no manganese and cobalt impurities are obtained. There is no need for subsequent complex extraction to remove manganese and nickel and cobalt separation processes, which greatly reduces the consumption of acid, alkali and extractant, reduces refining costs, and shortens the overall process flow and improves production efficiency.

[0021] (2) Not only can core metals nickel and cobalt be efficiently recovered from laterite nickel ore, but manganese can also be recovered through a special oxidation precipitation process and magnesium can be recovered through a magnesium precipitation process, so as to realize the tiered recovery and high-value utilization of four valuable metals: nickel, cobalt, manganese and magnesium. Among them, manganese can be used to obtain high-priced manganese products, magnesium can be used to obtain magnesium hydroxide or basic magnesium carbonate products, and some magnesium products can be returned to the process as a neutralizing agent for recycling, maximizing the exploitation of the resource value of laterite nickel ore and avoiding resource waste.

[0022] (3) The acid leaching process can be either high-pressure acid leaching or normal-pressure acid leaching, which is suitable for limonite-type, residual ore-type laterite nickel ore and mixed ore of any proportion; the manganese and cobalt recovery can be either step precipitation or combined precipitation, which can be flexibly adjusted according to production needs and raw material composition, and is suitable for production scenarios of different scales and raw material conditions, and is highly practical.

[0023] (4) The nickel washing liquid recovered by acid washing of filter cake after manganese and cobalt precipitation is returned to the leaching or countercurrent washing process, and part of the liquid after magnesium precipitation is returned as process water, realizing the resource reuse of process wastewater and reducing the consumption of fresh water and the amount of wastewater discharged. At the same time, the recovery of magnesium resources avoids the environmental burden caused by magnesium being discharged with tailings. The tailings are discharged in compliance with standards after neutralization treatment. The overall process is more green and environmentally friendly, which is in line with the green development trend of hydrometallurgy.

[0024] (5) By removing impurities through two stages of iron and aluminum removal, combined with manganese and cobalt cascade separation and nickel plating post-processing, the purity of MHP products is greatly improved, which can directly provide high-quality nickel raw materials for the EV battery industry chain. At the same time, the characteristics of magnesium product recycling, wastewater reuse, and reduced reagent consumption further reduce production energy consumption and costs, and enhance the market competitiveness and industrialization value of the process.

[0025] To achieve the foregoing and related objectives, one or more aspects of the invention include the features that will be described in detail below. The following description and accompanying drawings illustrate certain exemplary aspects of the invention. However, these aspects indicate only a few of the various ways in which the principles of the invention can be used. Furthermore, the invention is intended to encompass all such aspects and their equivalents. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 The flowchart is shown below for the method of comprehensive recovery of nickel, cobalt, manganese and magnesium from laterite nickel ore according to Embodiments 1 and 2 of the present invention. Figure 2 This is a flowchart of a method for the comprehensive recovery of nickel, cobalt, manganese and magnesium from laterite nickel ore according to Embodiment 3 of the present invention. Detailed Implementation

[0028] In the following description, numerous specific details are set forth for illustrative purposes and to provide a thorough understanding of one or more embodiments. However, it will be apparent that these embodiments may also be implemented without these specific details. In other instances, well-known structures and devices are shown in block diagram form for ease of description of one or more embodiments.

[0029] This invention can be modified and has various embodiments, with specific embodiments illustrated in the accompanying drawings. However, this invention is not limited to this particular implementation and all modifications, equivalents, and substitutions falling within the spirit and technical scope of this invention are to be understood as included.

[0030] In response to the aforementioned technical problems of low resource utilization, high production costs, lengthy processes, and significant environmental pressure in existing processes, this invention proposes a method for the comprehensive recovery of nickel, cobalt, manganese, and magnesium from laterite nickel ore, achieving efficient separation and high-value utilization of nickel, cobalt, manganese, and magnesium in laterite nickel ore.

[0031] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0032] To illustrate the method for comprehensive recovery of nickel, cobalt, manganese, and magnesium from laterite nickel ore provided by this invention. Figure 1 and Figure 2 A method flow for the comprehensive recovery of nickel, cobalt, manganese and magnesium from laterite nickel ore according to an embodiment of the present invention is shown.

[0033] like Figure 1 and Figure 2 As shown, this invention provides a method for the comprehensive recovery of nickel, cobalt, manganese, and magnesium from laterite nickel ore, comprising: S1: Acid leaching of laterite nickel ore to obtain leaching slurry; S2: The leaching slurry is countercurrently washed, and after washing, liquid-solid separation is performed to obtain the washed liquid and leaching residue, and the leaching residue is sent to the tailings neutralization process. S3: The washing liquid is subjected to a two-stage iron and aluminum removal treatment using limestone to obtain iron and aluminum removed liquid and iron and aluminum slag. During the iron and aluminum removal process, compressed air is introduced to oxidize ferrous iron. S4: The iron and aluminum removal liquid is subjected to manganese and cobalt recovery by oxidation precipitation method to obtain manganese product, cobalt product and manganese and cobalt precipitated liquid; S5: Add a precipitant to the manganese-cobalt precipitate solution to perform nickel precipitation treatment, and obtain nickel hydroxide product and nickel precipitate solution; S6: Add the precipitant to the nickel precipitation solution to perform magnesium precipitation treatment, and obtain magnesium product and magnesium precipitation solution; S7: A portion of the magnesium precipitation solution is returned to the washing process for recycling, and the remaining portion of the magnesium precipitation solution is combined with the leaching residue and recycled in the tailings neutralization process.

[0034] In this invention, after iron and aluminum removal treatment, the laterite nickel ore leaching solution is first converted into high-valence oxides and separated by oxidation precipitation under specific pH conditions to obtain manganese and cobalt-related products; then the precipitation pH value of the system is increased to precipitate nickel and prepare a nickel-only MHP product; finally, magnesium in the remaining solution is recovered to obtain magnesium products, thus achieving the stepwise separation and recovery of four valuable metals: nickel, cobalt, manganese, and magnesium.

[0035] In S1 and S2, the acid leaching method is high-pressure acid leaching or normal-pressure acid leaching, the leaching temperature is 90~280℃, and the leaching time is 0.5~8h; the laterite nickel ore is limonite-type laterite nickel ore, residual ore-type laterite nickel ore, or a mixture of the two in any proportion; the liquid-solid separation method is thickener separation or filter press separation.

[0036] In other words, lateritic nickel ore is leached with sulfuric acid, using either high-pressure acid leaching (HPAL) or atmospheric-pressure acid leaching processes. The leaching temperature is 90–280℃, and the leaching time is 0.5–8 hours. The raw material can be limonite-type, residual lateritic nickel ore, or a mixture of ores in any proportion, and can be mixed or fed into the high-pressure autoclave for leaching in batches. After leaching, the slurry undergoes liquid-solid separation using equipment such as thickeners and filter presses. The leaching residue is sent to the tailings neutralization process; the leaching liquid is subjected to countercurrent washing (CCD) using a multi-stage thickener in series to obtain the washed liquid, which is then sent to the iron and aluminum removal process.

[0037] In the S3 iron and aluminum removal process, the final pH value of the two-stage iron and aluminum removal is 3.5~5.2. Limestone is used as the impurity removal agent, and a two-stage iron and aluminum removal treatment is implemented. Compressed air is introduced simultaneously to remove divalent iron (Fe²⁺) from the solution. + ) is oxidized to trivalent iron (Fe³⁺) + This facilitates the separation of iron and aluminum by forming hydroxide precipitates. The final pH of the first-stage iron and aluminum removal process is controlled at 3.5~4.2, mainly used to remove most of the iron and aluminum impurities in the solution; the final pH of the second-stage iron and aluminum removal process is controlled at 4.5~5.2, used to deeply remove residual iron and aluminum impurities in the solution, ensuring the purity of the solution in subsequent processes.

[0038] After this process, two products are obtained: one is iron-aluminum slag, which is collected and discharged for treatment; the other is the liquid after iron and aluminum removal, which is sent to the subsequent manganese-cobalt step-by-step oxidation precipitation recovery process.

[0039] In the S4 manganese-cobalt step-by-step oxidation precipitation recovery process, during the process of recovering manganese and cobalt from the liquid after iron and aluminum removal using the oxidation precipitation method, step-by-step oxidation precipitation or combined oxidation precipitation is used to recover manganese and cobalt products from the liquid after iron and aluminum removal.

[0040] like Figure 1 As shown, the stepwise oxidation precipitation method is as follows: (1) Precipitation of manganese: An oxidant and a neutralizing agent are added to the solution after iron and aluminum removal, and manganese is precipitated by oxidation precipitation method. The oxidant can be one or more of oxygen, ozone, a mixture of oxygen and sulfur dioxide in any proportion, persulfate, hydrogen peroxide, nitrite, and perchlorate. The amount of oxidant added is equal to the amount of divalent manganese (Mn²⁺) in the solution. + The stoichiometric ratio of the chemical reaction is 1.0 to 10.0 times; the neutralizing agent can be one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, magnesium carbonate, magnesium bicarbonate, ammonium carbonate, ammonium bicarbonate, calcium oxide, magnesium oxide, sodium hydroxide, potassium hydroxide, ammonia, calcium hydroxide, magnesium hydroxide, calcium carbonate, and calcium bicarbonate, or one or more of limestone, magnesia, magnesite, dolomite, marble, etc.

[0041] The conditions for manganese precipitation treatment are as follows: the final pH is controlled at 4.5~5.5, the reaction temperature is room temperature~100℃, and the reaction time is 0.5~8h. Under the above conditions, divalent manganese in the solution is oxidized to hypervalent manganese and forms a precipitate.

[0042] After manganese precipitation, the slurry is filtered and washed to remove impurities from the surface of the precipitate. The washed filter cake is then acid-washed, with the acid-washing solution-to-solid ratio controlled at 2-10:1. The pH of the acid wash is adjusted to 1.0-3.0 with sulfuric acid to remove nickel precipitates from the filter cake. The nickel washing solution is returned to the leaching process or the CCD countercurrent washing process to achieve nickel recovery. After acid washing, a high-value manganese product is obtained, thus completing the manganese recovery process.

[0043] (2) Cobalt precipitation: The mother liquor after manganese oxidation (i.e., the liquid after manganese removal) is treated with cobalt precipitation using the same process principle as manganese oxidation. An oxidant and a neutralizing agent are added to the liquid after manganese removal. The type of oxidant is the same as that used in manganese oxidation, and the amount added is equal to the amount of divalent cobalt (Co²⁺) in the solution. + The chemical reaction stoichiometry is 1.0 to 10.0 times; the type of neutralizing agent is consistent with that of manganese oxide precipitation.

[0044] The cobalt precipitation treatment conditions are as follows: the final pH is controlled at 5.0~6.0, the reaction temperature is room temperature~100℃, and the reaction time is 0.5~8h. Under the above conditions, divalent cobalt in the solution is oxidized to hypervalent cobalt and forms a precipitate.

[0045] After cobalt precipitation, the slurry is filtered and washed. The washed filter cake is then subjected to the same acid washing process as the manganese oxide precipitation filter cake to remove the nickel entrained in the filter cake. The nickel washing solution is returned to the leaching process or the CCD countercurrent washing process. After acid washing, a high-priced cobalt product is obtained, thus completing the cobalt recovery.

[0046] like Figure 2 As shown, the combined oxidation precipitation method combines the manganese oxidation and cobalt oxidation precipitation processes into one step, simplifying the process flow. The specific process is as follows: Oxidizing agent and neutralizing agent are directly added to the solution after iron and aluminum removal, controlling the final pH to 5.0~6.0, the reaction temperature to room temperature~100℃, and the reaction time to 0.5~8h; wherein, the type of oxidizing agent is consistent with that of the stepwise precipitation, and the amount added is equal to the amount of divalent manganese (Mn²⁺) in the solution. + ) and divalent cobalt (Co² + The chemical reaction stoichiometry is 1.0 to 10.0 times the sum of the chemical reaction stoichiometry, and the type of neutralizing agent is consistent with that of stepwise precipitation.

[0047] After sedimentation, the slurry is filtered and washed. The washed filter cake is then subjected to the same acid washing process as the stepwise sedimentation to remove the entrained nickel. The nickel washing solution is returned to the previous process. After acid washing, manganese and cobalt enriched products are obtained, completing the simultaneous recovery of manganese and cobalt.

[0048] After both of the above implementation methods are completed, a manganese-cobalt precipitated liquid is obtained, which is then sent to the subsequent nickel precipitation process.

[0049] In the S5 nickel plating process, a precipitant is added to the liquid after manganese and cobalt plating. The precipitant can be one or more of the following: sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, magnesium carbonate, magnesium bicarbonate, ammonium carbonate, ammonium bicarbonate, calcium oxide, magnesium oxide, sodium hydroxide, potassium hydroxide, ammonia, calcium hydroxide, magnesium hydroxide, calcium carbonate, and calcium bicarbonate. The process conditions for nickel plating are controlled as follows: final pH is controlled at 7.0~9.0, reaction temperature is room temperature~100℃, and reaction time is 0.5~8 hours.

[0050] The precipitation process in this step can be flexibly selected according to production needs, specifically including three types: First, the direct precipitation process with neutralizing agent, which is simple to operate and has a low cost; second, the base activation control process (ENFI patented technology), which uses a magnesium-containing solution to first react with the precipitant to generate active magnesium hydroxide, and then the active magnesium hydroxide reacts with nickel in the solution to generate nickel hydroxide precipitate; third, the lime precipitation process, which generates MHP product and gypsum after the reaction, and the MHP solid product is separated by physical means.

[0051] After precipitation, the precipitated slurry undergoes liquid-solid separation, yielding an underflow (MHP crude product) and a nickel precipitation residue. The underflow requires post-treatment to remove residual impurities and improve product purity. This post-treatment includes one or more of the following: weak acid washing, alkaline washing, and washing with a nickel-cobalt solution. The weak acid used for washing can be one or more of sulfuric acid, hydrochloric acid, nitric acid, carbonic acid, or organic acids. The alkaline used for alkaline washing can be one or more of sodium hydroxide, potassium hydroxide, ammonia, or carbonates. The amount of reagent used in the post-treatment is 0.01% to 100% of the MHP solids, the treatment temperature is room temperature to 100°C, and the treatment time is 0.5 to 8 hours.

[0052] After post-processing, high-quality nickel hydroxide (MHP) product is obtained. This product is almost free of manganese and cobalt impurities and can be directly used as a raw material for the EV battery industry chain. The nickel precipitated solution is then sent to the subsequent magnesium precipitation process.

[0053] In the S6 magnesium precipitation process, a precipitant is added to the nickel precipitation solution. The precipitant can be one or more of the following: sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ammonium carbonate, ammonium bicarbonate, calcium oxide, sodium hydroxide, potassium hydroxide, ammonia, calcium hydroxide, calcium carbonate, and calcium bicarbonate. The process conditions for magnesium precipitation are controlled as follows: final pH is controlled at 9.0~11.0, reaction temperature is room temperature~100℃, and reaction time is 0.5~8 hours.

[0054] This process produces magnesium hydroxide or basic magnesium carbonate. A portion of the magnesium product can be recycled as a neutralizing agent in preceding neutralization processes (such as iron and aluminum removal, manganese and cobalt precipitation, and nickel precipitation), reducing reagent procurement costs. The remaining magnesium product is sold as a commodity, achieving high-value recovery of magnesium resources. The magnesium-precipitated liquid is sent to subsequent tailings recycling and tailings neutralization processes.

[0055] In S7, the magnesium precipitation liquid is treated in separate ways: one part is returned to the system as washing water and other process water in the CCD countercurrent washing process, realizing the resource reuse of process wastewater and reducing fresh water consumption and wastewater discharge; the other part is combined with the leaching residue generated in the leaching process and enters the tailings neutralization process together.

[0056] In the tailings neutralization process, a neutralizing agent is added to the mixed leaching residue and the remaining magnesium precipitation liquid to adjust the pH of the system to the standard range. After treatment, tailings slurry is obtained, and the tailings slurry is discharged after testing and meeting the standards.

[0057] Through the above seven processes, this invention achieves the tiered separation and high-value recovery of four valuable metals—nickel, cobalt, manganese, and magnesium—from laterite nickel ore.

[0058] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and provides detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0059] Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0060] Example 1

[0061] The raw material is limonite-type laterite nickel ore with a nickel content of 1.2%, an iron content of 45%, and a magnesium content of 2%. After high-pressure leaching at an acid-to-ore ratio of 250 kg / t ore, a temperature of 255℃, and a leaching time of 1 hour, the ore is washed countercurrently using a seven-stage CCD thickener. Two stages of iron and aluminum removal are performed using limestone. The first stage has an endpoint pH of 4.0, and the second stage has an endpoint pH of 4.8. Compressed air is introduced during the process to oxidize ferrous iron. The iron-aluminum slag from the first stage is filtered and discarded, while the slag from the second stage is returned to the leaching process to recover the entrained nickel and cobalt precipitates.

[0062] After removing iron and aluminum, magnesium oxide was added to the slurry as a neutralizing agent. The final pH was controlled at 4.6, the temperature at 70℃, and the time at 6 hours. Manganese oxidation was carried out using oxygen and sulfur dioxide (sulfur dioxide volume content 10%). After manganese removal, the slurry was filtered and washed. The filter cake was then acid-washed with a liquid-to-solid ratio of 3:1. The pH of the acid washing was adjusted to 1.5 with sulfuric acid to remove the entrained nickel precipitate. The nickel washing solution was returned to the CCD for washing to obtain a high-value manganese product.

[0063] Magnesium oxide was added as a neutralizing agent to the cobalt-removed solution. The final pH was controlled at 5.8, the temperature at 70℃, and the time at 6 hours. Sodium persulfate was used for manganese oxidation, with the amount of sodium persulfate added being twice the molar amount of cobalt. After cobalt removal, the slurry was filtered and washed. The filter cake was then acid-washed with a liquid-to-solid ratio of 3:1. The pH of the acid washing was adjusted to 1.5 with sulfuric acid to remove the entrained nickel precipitate. The nickel washing solution was returned to the CCD for washing to obtain a high-value cobalt product.

[0064] After manganese and cobalt precipitation, the solution was treated with magnesium oxide for a first-stage nickel precipitation. The final pH was controlled at 7.8, the precipitation temperature at 60℃, and the precipitation time at 4 hours.

[0065] The precipitated slurry was subjected to liquid-solid separation. The underflow after separation was treated by washing with sodium hydroxide solution at 1% of the solid content of MHP, at a temperature of 30℃, for 2 hours.

[0066] The final product is a high-quality nickel hydroxide (MHP) product with a nickel content of 47%, a manganese and cobalt content of <0.02%, and a sulfur content of <0.3%.

[0067] The precipitate was subjected to a two-stage nickel precipitation process, with the final pH controlled at 8.3, the precipitation temperature at 60℃, and the precipitation time at 4 hours. After nickel precipitation, the liquid and solid were separated, and the underflow was returned to the leaching solution to dissolve and recover nickel.

[0068] After nickel precipitation, the solution can be precipitated with sodium carbonate to produce basic magnesium carbonate. The final pH is controlled at 9.5, the precipitation temperature is 55℃, and the precipitation time is 4 hours.

[0069] After precipitation, part of the magnesium product is returned to the above process as a neutralizing agent, and part is sold as a product. Part of the magnesium precipitation liquid is returned as washing water for processes such as CCD, and the remainder is mixed with the leaching residue and then combined into the tailings for neutralization.

[0070] Example 2

[0071] The raw material is residual laterite nickel ore with a nickel content of 1.05%, an iron content of 38%, and a magnesium content of 3.5%. After atmospheric pressure acid leaching at an acid-to-ore ratio of 220 kg / t ore, a leaching temperature of 95℃, and a leaching time of 6 hours, the ore is washed countercurrently using a six-stage CCD thickener. Two-stage iron and aluminum removal is performed using limestone. The first stage has an endpoint pH of 3.6, and the second stage has an endpoint pH of 5.1. Compressed air is continuously introduced during the process to oxidize ferrous iron. The iron-aluminum slag from the first stage is filtered and discharged, while the iron-aluminum slag from the second stage is returned to the leaching process to recover the nickel and cobalt metals carried in the slag.

[0072] After iron and aluminum removal, calcium hydroxide was used as a neutralizing agent in the slurry. The pH of the final manganese precipitation was controlled at 5.2, the reaction temperature was 80℃, and the reaction was maintained at this temperature for 5.5 hours. Hydrogen peroxide was used as an oxidant for the oxidation and precipitation of divalent manganese. After manganese removal, the slurry was filtered and washed with water. The filter cake was then subjected to acid washing treatment with a solid-liquid ratio of 3:1. Sulfuric acid was used to adjust the pH of the acid washing to 1.5 to wash away nickel elements entrained in the precipitate. The resulting nickel washing solution was recycled to the CCD washing process for reuse, ultimately producing a high-priced manganese product.

[0073] After manganese removal, sodium hydroxide was used as a neutralizing agent to control the pH at the final cobalt precipitation point at 5.9. The reaction temperature was 80℃, and the reaction time was 5.5 h. Ozone was used as the oxidant, with an oxidant dosage of 2.0 times the molar amount of cobalt, to achieve selective oxidation and precipitation of cobalt. After cobalt removal, the slurry was filtered and washed, and the filter cake was treated under the same acid washing conditions. The nickel washing solution was returned to the system for reuse, and a high-purity, high-value cobalt product was obtained through separation.

[0074] After manganese and cobalt precipitation, the liquid was subjected to selective nickel precipitation with light magnesium oxide. The final precipitation pH was 8.0, the reaction temperature was 65℃, and the precipitation time was 4 hours. The precipitated slurry was separated into liquid and solid components by a filter press. The underflow was washed and purified with a weak alkaline solution. Ammonia was selected as the washing agent, and the amount of the agent was 1% of the solid mass of MHP. The washing temperature was 35℃, and the treatment time was 2 hours, which effectively removed impurity ions.

[0075] The final product is a high-quality single nickel hydroxide (MHP) product with a nickel content of 46.8%, manganese and cobalt impurities of <0.02%, and sulfur content of <0.3%. The leaching solution after the first stage of nickel precipitation undergoes a second stage of deep nickel precipitation, with the final pH controlled at 8.5, precipitation temperature at 65℃, and reaction time at 4 hours. The underflow from the leaching solution is returned to dissolve and recover residual nickel resources.

[0076] After the second-stage nickel precipitation, magnesium is precipitated using sodium bicarbonate to produce basic magnesium carbonate. The final precipitation pH is 10.0, the precipitation temperature is 50℃, and the reaction time is 4 hours. A portion of the produced magnesium salt is recycled to the neutralization stages of this process to reduce reagent consumption, while the remaining magnesium product is sold externally. A portion of the magnesium precipitation solution is reused as CCD washing water, and the remaining waste liquid is mixed with the leaching residue and sent to the tailings neutralization stage for harmless treatment.

[0077] Example 3

[0078] The raw material is a mixture of limonite and residual laterite nickel ore (mixed mass ratio 1:1), with a nickel content of 1.12%, an iron content of 42%, and a magnesium content of 2.8%. A high-pressure acid leaching process is employed, with an acid-to-ore ratio of 235 kg / t ore, a leaching temperature of 220℃, and a leaching time of 2 hours. The leached slurry undergoes a seven-stage CCD countercurrent washing process. A two-stage limestone process is used to remove iron and aluminum ions. The first stage has an endpoint pH of 3.9, and the second stage has an endpoint pH of 4.9. Compressed air is introduced to force oxidation of ferrous ions. The iron and aluminum slag from the first stage is filtered and discarded, while the iron and aluminum slag from the second stage is returned to the leaching system to recover valuable metals lost.

[0079] This embodiment employs a combined manganese and cobalt oxidation precipitation process. After removing iron and aluminum, the liquid is neutralized with dolomite powder. The pH at the precipitation endpoint is uniformly controlled at 5.5, the reaction temperature at 75℃, and the reaction time at 6 hours. Potassium persulfate composite oxidant is used, with the total amount of oxidant added being 2.0 times the total molar amount of manganese and cobalt in the solution, simultaneously achieving co-precipitation of manganese and cobalt through oxidation.

[0080] After filtration and washing of the manganese-cobalt coprecipitated slurry, the filter cake is acid-washed and refined. The acid washing solution has a solid-liquid ratio of 3:1, and the pH of the acid washing solution is adjusted to 1.5 with sulfuric acid to remove adsorbed nickel. All the nickel washing solution is returned to the CCD washing process to obtain the manganese-cobalt composite enriched product.

[0081] After manganese and cobalt precipitation, the liquid was subjected to a first-stage nickel precipitation using magnesium oxide precipitant, with an endpoint pH of 7.9, a precipitation temperature of 60℃, and a reaction time of 4 hours. After solid-liquid separation of the slurry, the crude MHP product was purified by washing with a low-concentration sodium hydroxide solution at 1% of the solid MHP amount, at a washing temperature of 30℃, and held at that temperature for 2 hours to remove sulfates and trace impurities.

[0082] The final product obtained is a high-purity single-nickel MHP product with a nickel content of 47.2%, a manganese and cobalt content of <0.02%, and a sulfur content of <0.3%. The mother liquor from the first stage of nickel precipitation is used for a second stage of nickel precipitation, with the pH controlled at 8.4, the temperature at 60℃, and the reaction time controlled at 4 hours. The nickel slag from the second stage is returned to the leaching process for recycling.

[0083] Basic magnesium carbonate was prepared from the nickel precipitation solution using sodium carbonate composite precipitant. The final precipitation pH was 9.8, the precipitation temperature was 55℃, and the reaction time was 4 hours. Part of the magnesium product was recycled as a neutralizing agent in the system, and part was sold externally. The magnesium precipitation filtrate was divided proportionally; a portion was reused as process water, and the remaining waste liquid, along with the leaching residue, was neutralized and disposed of in the tailings.

[0084] Comparative Example 1

[0085] The raw material used was the same limonite-type laterite nickel ore as in Example 1, with a nickel content of 1.2%, an iron content of 45%, and a magnesium content of 2%. The acid leaching, acid-to-ore ratio, leaching temperature, leaching time, seven-stage CCD countercurrent washing, two-stage iron and aluminum removal operation and process parameters were all completely consistent with those in Example 1.

[0086] The difference lies in the following: the selective oxidation and stepwise precipitation / combined precipitation process of manganese and cobalt in this invention is cancelled; after removing iron and aluminum, manganese and cobalt are not separated in advance, and the traditional process is directly used for nickel-cobalt-manganese co-precipitation; an alkaline neutralizing agent is directly added to adjust the pH of the system to 7.8~8.5, and nickel, cobalt and most of the manganese elements in the solution are precipitated simultaneously, directly producing nickel-cobalt-manganese composite MHP intermediate product.

[0087] The process does not include a separate magnesium recovery section. Magnesium ions in the solution remain in the final waste liquid throughout the process and are directly disposed of as solid waste in landfill after neutralization with the tailings, resulting in a complete waste of magnesium resources.

[0088] The resulting composite MHP product has high levels of manganese and cobalt impurities, with manganese content ranging from 1.8% to 2.5% and cobalt content ranging from 1.2% to 1.6%, making it unsuitable for direct use in the preparation of battery-grade raw materials. Subsequent processes such as extraction to remove manganese, deep separation of nickel and cobalt, and multi-stage purification and refining are required, significantly increasing the consumption of acid and alkali reagents and extractants, lengthening the process flow by more than 30%, significantly increasing the overall smelting and refining costs, resulting in low resource utilization and a greater environmental treatment burden.

[0089] In summary, the comparative experiments of Examples 1-3 and Comparative Example 1 demonstrate that the process of this invention has significant technical advantages and application value compared to the traditional laterite nickel ore co-precipitation process. Examples 1-3 respectively use limonite-type, residual ore-type, and mixed laterite nickel ore as raw materials, are compatible with high-pressure and atmospheric-pressure leaching modes, and can flexibly select manganese-cobalt stepwise precipitation or combined precipitation processes. Through precise control of the oxidation system, reaction pH, and material circulation, the tiered separation and high-value recovery of nickel, cobalt, manganese, and magnesium are achieved. The prepared nickel hydroxide (MHP) product has a stable nickel grade of 46.8%-47.2%, manganese and cobalt impurity content of <0.02%, and sulfur content of <0.3%, which can be directly used as a battery-grade raw material without the need for subsequent complex refining processes. At the same time, magnesium resources are recovered to prepare magnesium-based products and partially recycled. The acid-washed nickel-rich solution and secondary nickel slag are recycled in a closed loop, significantly reducing reagent consumption and production costs, and improving the comprehensive utilization rate of resources.

[0090] Compared with the traditional co-precipitation process in Comparative Example 1, the lack of pre-separation of manganese and cobalt resulted in high impurity content in the MHP product, requiring additional refining steps. Furthermore, the magnesium resources were not recycled, leading to drawbacks such as a long process flow, high production costs, resource waste, and significant environmental pressure.

[0091] Therefore, this invention effectively solves the technical problems of MHP multi-impurity co-precipitation, high refining cost, and low utilization rate of valuable metals in traditional laterite nickel ore hydrometallurgical processes. The process has wide adaptability to raw materials, stable operation, and is green and environmentally friendly, and has good prospects for industrial application. It can effectively support the stable supply of high-quality nickel raw materials in the EV battery industry chain.

[0092] The above are merely preferred embodiments of the present invention and do not limit the scope of protection of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any changes, modifications, substitutions, integrations, and parameter alterations to these embodiments within the spirit and principles of the present invention, achieved through conventional substitutions or by achieving the same function without departing from the principles and spirit of the present invention, fall within the scope of protection of the present invention.

Claims

1. A method for the comprehensive recovery of nickel, cobalt, manganese, and magnesium from laterite nickel ore, characterized in that, include: S1: Acid leaching of laterite nickel ore to obtain leaching slurry; S2: The leaching slurry is countercurrently washed, and after washing, liquid-solid separation is performed to obtain the washed liquid and leaching residue, and the leaching residue is sent to the tailings neutralization process. S3: The washing liquid is subjected to a two-stage iron and aluminum removal treatment using limestone to obtain iron and aluminum removed liquid and iron and aluminum slag. During the iron and aluminum removal process, compressed air is introduced to oxidize ferrous iron. S4: The iron and aluminum removal liquid is subjected to manganese and cobalt recovery by oxidation precipitation method to obtain manganese product, cobalt product and manganese and cobalt precipitated liquid; during the manganese and cobalt recovery process, when the manganese filter cake and cobalt filter cake are acid washed, the acid washing liquid solid ratio is 2~10:1, and sulfuric acid is used to adjust the acid washing pH to 1.0~3.

0. S5: Add a precipitant to the manganese-cobalt precipitate solution to perform nickel precipitation treatment, and obtain nickel hydroxide product and nickel precipitate solution; S6: Add the precipitant to the nickel precipitation solution to perform magnesium precipitation treatment, and obtain magnesium product and magnesium precipitation solution; S7: A portion of the magnesium precipitation solution is returned to the washing process for recycling, and the remaining portion of the magnesium precipitation solution is combined with the leaching residue and recycled in the tailings neutralization process.

2. The method for comprehensive recovery of nickel, cobalt, manganese, and magnesium from laterite nickel ore according to claim 1, characterized in that, In S1, the acid leaching method is high-pressure acid leaching or normal-pressure acid leaching, the leaching temperature is 90~280℃, and the leaching time is 0.5~8h; The laterite nickel ore is limonite-type laterite nickel ore, residual laterite nickel ore, or a mixture of the two in any proportion. The liquid-solid separation method is either thickener separation or filter press separation.

3. The method for comprehensive recovery of nickel, cobalt, manganese, and magnesium from laterite nickel ore according to claim 1, characterized in that, In S2, the washing methods are multi-stage thickener series countercurrent washing, on-machine washing of filter press, or slurry washing.

4. The method for comprehensive recovery of nickel, cobalt, manganese, and magnesium from laterite nickel ore according to claim 1, characterized in that, In S3, the final pH values ​​for the two iron and aluminum removal stages are 3.5 to 5.2, with the final pH value for the first stage of iron and aluminum removal being 3.5 to 4.2 and the final pH value for the second stage being 4.5 to 5.

2.

5. The method for comprehensive recovery of nickel, cobalt, manganese, and magnesium from laterite nickel ore according to claim 1, characterized in that, In step S4, during the recovery of manganese and cobalt from the iron-aluminum-removed liquid using an oxidation precipitation method, a stepwise oxidation precipitation process is employed for the recovery of manganese and cobalt from the iron-aluminum-removed liquid; wherein... First, under pH conditions of 4.5~5.5, an oxidant and a neutralizing agent are added sequentially to the liquid after iron and aluminum removal to precipitate manganese. After the manganese precipitation reaction is completed, the slurry is filtered and washed to obtain a manganese filter cake, and the manganese filter cake is acid washed to remove impurities to obtain manganese product. Then, under pH conditions of 5.0~6.0, oxidant and neutralizing agent are added sequentially to the manganese-removed liquid to precipitate cobalt. After the cobalt precipitation reaction is completed, the slurry is filtered and washed to obtain a cobalt filter cake, and the cobalt filter cake is acid washed to remove impurities to obtain the cobalt product.

6. The method for comprehensive recovery of nickel, cobalt, manganese, and magnesium from laterite nickel ore according to claim 5, characterized in that, In S4, the oxidant is selected from one or more of oxygen, ozone, a mixture of oxygen and sulfur dioxide in any proportion, persulfate, hydrogen peroxide, nitrite, and perchlorate. The neutralizing agent is selected from one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, magnesium carbonate, magnesium bicarbonate, ammonium carbonate, ammonium bicarbonate, calcium oxide, magnesium oxide, sodium hydroxide, potassium hydroxide, ammonia, calcium hydroxide, magnesium hydroxide, calcium carbonate, and calcium bicarbonate, or one or more of limestone, magnesia powder, magnesite, dolomite, and marble.

7. The method for comprehensive recovery of nickel, cobalt, manganese, and magnesium from laterite nickel ore according to claim 5, characterized in that, In S4, the amount of oxidant added for manganese precipitation is 1.0 to 10.0 times the stoichiometric ratio of divalent manganese, and the amount of oxidant added for cobalt precipitation is 1.0 to 10.0 times the stoichiometric ratio of divalent cobalt.

8. The method for comprehensive recovery of nickel, cobalt, manganese, and magnesium from laterite nickel ore according to claim 1, characterized in that, In step S5, a precipitant is added to the liquid after manganese and cobalt precipitation to carry out a nickel precipitation reaction; wherein, the nickel precipitation conditions are: pH value of 7.0~9.0, precipitation temperature of room temperature~100℃, and reaction time of 0.5~8h; After the precipitation reaction is completed, the slurry is subjected to liquid-solid separation to obtain a bottom stream and a supernatant containing MHP solids. The separated underflow is washed to obtain the nickel hydroxide product; wherein, the amount of washing agent used in the washing process is 0.01~100% of the solid amount of MHP, the washing temperature is room temperature~100℃, and the washing time is 0.5~8h.

9. The method for comprehensive recovery of nickel, cobalt, manganese, and magnesium from laterite nickel ore according to claim 8, characterized in that, In S5, the precipitant is selected from one or more of the following: sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, magnesium carbonate, magnesium bicarbonate, ammonium carbonate, ammonium bicarbonate, calcium oxide, magnesium oxide, sodium hydroxide, potassium hydroxide, ammonia, calcium hydroxide, magnesium hydroxide, calcium carbonate, and calcium bicarbonate.

10. The method for comprehensive recovery of nickel, cobalt, manganese, and magnesium from laterite nickel ore according to claim 9, characterized in that, In S5, the washing process employs one or a combination of weak acid washing, alkaline washing, and nickel-cobalt solution washing; among these... The acid solution used for the weak acid washing is selected from one or more of carbonic acid and organic acids. The alkaline solution used for washing is selected from one or more of sodium hydroxide, potassium hydroxide, ammonia, and carbonates.

11. The method for comprehensive recovery of nickel, cobalt, manganese, and magnesium from laterite nickel ore according to claim 1, characterized in that, In S6, the magnesium precipitation conditions are: pH value of 9.0~11.0, precipitation temperature of room temperature~100℃, and reaction time of 0.5~8h.

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