Method for precipitating nickel and cobalt from nickel- and cobalt-containing solution, and nickel-cobalt hydroxide product

Abstract

Provided in the present disclosure are a method for precipitating nickel and cobalt from a nickel- and cobalt-containing solution, and a nickel-cobalt hydroxide product. The method comprises: step S100, performing a seed crystal pretreatment reaction on a nickel- and cobalt-containing solution by using a first nickel-cobalt precipitation underflow, so as to form a pretreated nickel-cobalt ore slurry; step S200, adding an alkaline precipitation inducer to a second nickel-cobalt precipitation underflow or a first nickel-cobalt precipitation overflow to perform an alkali conversion reaction, so as to form an alkali-converted crystal slurry; step S300, continuously introducing the pretreated nickel-cobalt ore slurry and the alkali-converted crystal slurry into a reactor for a nickel-cobalt precipitation reaction, so as to obtain a nickel-cobalt-precipitated ore slurry; step S400, continuously performing a thickening and separation treatment on the nickel-cobalt-precipitated ore slurry; and step S500, sequentially filtering and washing a third nickel-cobalt precipitation underflow, so as to obtain a nickel-cobalt hydroxide product. Problems existing during the precipitation of nickel and cobalt from nickel- and cobalt-containing solutions in the prior art are solved, such as a small particle size and the poor settleability of MHP, the high moisture content of a filter cake, a low precipitation rate, and a high magnesium content before the implementation of technical improvements.

Description

Methods for precipitating nickel and cobalt in nickel-cobalt solutions and nickel-cobalt hydroxide products

[0001] This disclosure claims priority to Chinese Patent Application No. 202510145096.9, filed on February 10, 2025, entitled “Method for precipitating nickel and cobalt in a nickel-cobalt solution and nickel-cobalt hydroxide product”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of hydrometallurgical technology for laterite nickel ore, and more specifically, to a method for precipitating nickel and cobalt in a nickel-cobalt-containing solution and a nickel-cobalt hydroxide product. Background Technology

[0003] Nickel-cobalt solutions, such as acid leaching solutions for removing iron and aluminum from laterite nickel ore, are obtained through hydrometallurgical processing of laterite nickel ore. The main processes include atmospheric leaching and high-pressure leaching, typically using sulfuric acid leaching. High-pressure acid leaching is used to treat limonite-type laterite nickel ore, offering advantages such as short leaching time, low iron leaching rate, high nickel and cobalt leaching and recovery rates, and low production costs. In recent years, it has become the preferred process for most new hydrometallurgical projects involving laterite nickel ore. The high-pressure leaching process for laterite nickel ore mainly includes high-pressure acid leaching, slurry neutralization, countercurrent washing, neutralization and impurity removal, and nickel-cobalt precipitation. The nickel-cobalt precipitation step is for the solution after neutralization and impurity removal from the high-pressure acid leaching solution of laterite nickel ore; this solution is also known as the acid leaching solution for removing iron and aluminum from laterite nickel ore.

[0004] Existing nickel-cobalt precipitation processes often employ sodium hydroxide or sulfide precipitation methods, for example:

[0005] Patent CN101575676A discloses a method for iron precipitation and nickel-cobalt enrichment. In the nickel-cobalt enrichment step, a sulfiding agent is used for sulfidation precipitation. This patent uses one or more of the following sulfiding agents for nickel-cobalt precipitation: hydrogen sulfide, persulfide, sodium hydrosulfide, sodium sulfide, potassium sulfide, ammonium sulfide, magnesium sulfide, and zinc sulfide. Hydrogen sulfide exhibits the best precipitation effect, but it is highly toxic, requiring sophisticated operation and system specifications, and the intermediate products from sulfidation precipitation are difficult to process.

[0006] Patent CN102061387A discloses a two-stage nickel precipitation method. NaOH solution is added to a magnesium-containing nickel sulfate solution to adjust the pH to 7.5–8.5, the reaction temperature is 20–80℃, and the reaction time is 0.5–3 hours. The resulting precipitate is separated from the mother liquor. The precipitate proceeds to the next step, where NaOH solution is added to the mother liquor to adjust the pH to 9–10, the reaction temperature is 20–80℃, and the reaction time is 0.5–3 hours. Finally, the resulting precipitate is separated from the mother liquor and returned to the stirred leaching system for circulation. This patent directly uses sodium hydroxide or a mixed alkaline solution to precipitate nickel and cobalt, resulting in fine products that are difficult to settle, leading to a high water content in the product.

[0007] The process for preparing cobalt hydroxide from cobalt sulfate solution proposed in patent CN101921001A involves first precipitating the cobalt sulfate solution with magnesium hydroxide slurry in a primary cobalt precipitation tank. The resulting primary cobalt precipitation slurry is then passed through a primary cobalt precipitation buffer tank. 30%–50% of the slurry is returned to the primary cobalt precipitation tank, and the remaining slurry is pressure filtered. The filter cake obtained from the filter press is sent to a drying process, and the dried cobalt hydroxide is the product. The filtrate is then subjected to a second cobalt precipitation with magnesium hydroxide. This technology directly uses magnesium hydroxide as a precipitant; however, its alkalinity is limited. While this avoids localized over-alkalinity, the activity of magnesium hydroxide decreases after slurry preparation, resulting in a low cobalt precipitation rate.

[0008] In summary, the hydrogen sulfide precipitation process for nickel and cobalt is widely used due to its advantages, including high precipitation rate, low precipitation pH, and the ability to recover nickel and cobalt even under acidic leachate conditions without further purification. However, hydrogen sulfide is highly toxic, posing significant safety and environmental risks, and the subsequent processing of the intermediate products obtained from precipitation is extremely complex. The sodium hydroxide precipitation process for nickel and cobalt is simple and requires less equipment investment. However, the inventors realized that directly using strongly alkaline sodium hydroxide as a precipitant results in small particle size and poor settling ability in the nickel-cobalt hydroxide (MHP) precipitate, which is detrimental to the liquid-solid separation process. Furthermore, the high moisture content of the filter cake creates difficulties for subsequent transportation and processing. In addition, directly using magnesium hydroxide as a precipitant, due to its limited alkalinity and low activity, easily leads to a low precipitation rate.

[0009] In view of this, this disclosure is hereby made. Summary of the Invention

[0010] In view of the above problems, the purpose of this disclosure is to provide a method for precipitating nickel and cobalt in a nickel-cobalt solution and a nickel-cobalt hydroxide product, so as to solve the problems of small MHP particle size and difficulty in settling, high moisture content of filter cake, or poor precipitation rate, as well as high magnesium content before the technical improvement when precipitating nickel and cobalt in a nickel-cobalt solution.

[0011] To achieve the above objectives, according to one aspect of this disclosure, a method for precipitating nickel and cobalt in a nickel-cobalt-containing solution is provided. The cations in the nickel-cobalt-containing solution include nickel ions, cobalt ions, magnesium ions, and manganese ions. The method includes: step S100, performing a seed pretreatment reaction on the nickel-cobalt-containing solution using a first nickel-cobalt precipitation underflow to form a pretreated nickel-cobalt slurry; step S200, adding an alkaline precipitation inducer to a second nickel-cobalt precipitation underflow to perform an alkaline conversion reaction to form an alkaline-converted slurry; or, adding an alkaline precipitation inducer to the first nickel-cobalt precipitation overflow to perform an alkaline conversion reaction. In step S300, the pretreated nickel-cobalt slurry and the alkali-converted slurry are continuously fed into a reactor for nickel-cobalt precipitation reaction to obtain nickel-cobalt precipitated slurry. In step S400, the nickel-cobalt precipitated slurry is continuously subjected to thickening separation treatment to obtain nickel-cobalt precipitate underflow and nickel-cobalt precipitate overflow. The nickel-cobalt precipitate underflow consists of a first nickel-cobalt precipitate underflow, a second nickel-cobalt precipitate underflow, and a third nickel-cobalt precipitate underflow. The nickel-cobalt precipitate overflow includes the first nickel-cobalt precipitate overflow. In step S500, the third nickel-cobalt precipitate underflow is sequentially filtered and washed to obtain nickel-cobalt hydroxide product.

[0012] One optional technical solution is that, in step S100 above, the temperature of the seed crystal pretreatment reaction is 25℃~100℃, preferably 50℃~80℃, and the time of the seed crystal pretreatment reaction is 0.1h~10h, preferably 1h~5h.

[0013] One optional technical solution is that, in step S100 above, the mass of the first nickel-cobalt precipitate underflow is 1% to 99% of the total mass of the nickel-cobalt precipitate underflow.

[0014] One optional technical solution is that, in step S200 above, the total mass concentration of the alkaline precipitation inducer is 0.1% to 60%, preferably 3% to 20%, and more preferably 3% to 15%.

[0015] One optional technical solution is that, in step S200 above, the alkaline precipitation inducer is a mixture of an alkaline substance and water, wherein the alkaline substance is selected from any one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide and carbonates.

[0016] One optional technical solution is that, in step S200 above, the alkaline substance is a mixture of sodium hydroxide and potassium hydroxide, and the mass ratio of sodium hydroxide to potassium hydroxide is (1-4):(1-4).

[0017] One optional technical solution is that, based on the theoretical total number of hydroxide and carbonate ions required for nickel-cobalt precipitation in the pretreated nickel-cobalt slurry, the total number of hydroxide and / or carbonate ions in the alkaline precipitation inducer is 0.5 to 1.5 times the theoretical total number of moles, preferably 0.8 to 0.9 times.

[0018] One optional technical solution is that, in the above step S200, the temperature of the alkali conversion reaction is 25-100℃, preferably 50℃-60℃, and the time of the alkali conversion reaction is 0.1-30min, preferably 1min-10min, and more preferably 3min-5min.

[0019] One optional technical solution is that, in step S200 above, the mass of the first nickel-cobalt precipitate overflow is 1% to 99% of the total mass of the nickel-cobalt precipitate overflow, preferably 5% to 30%.

[0020] One optional technical solution is that, in step S200 above, the mass of the second nickel-cobalt precipitate underflow is 1% to 99% of the total mass of the nickel-cobalt precipitate underflow.

[0021] One of the optional technical solutions is that when an alkaline precipitation inducer is added to the first nickel-cobalt precipitate overflow to carry out an alkaline conversion reaction and form an alkaline conversion slurry, the mass ratio of the first nickel-cobalt precipitate underflow, the second nickel-cobalt precipitate underflow, and the third nickel-cobalt precipitate underflow is (55%~89%):(10%~40%):(1%~5%).

[0022] One optional technical solution is that the temperature of the above nickel-cobalt precipitation reaction is 50℃~70℃, the reaction time is 0.5h~5h, and the nickel-cobalt precipitation rate in the nickel-cobalt precipitation reaction is 70%~98%.

[0023] One optional technical solution is that the cationic composition of the above-mentioned nickel-cobalt solution is as follows: nickel ions 0.1g / L~120g / L, cobalt ions 0.1g / L~120g / L, magnesium ions 0.5g / L~25g / L, and divalent manganese ions 0.5g / L~10g / L. More preferably, nickel ions 3g / L~5g / L, cobalt ions 0.2g / L~0.5g / L, magnesium ions 5g / L~8g / L, and divalent manganese ions 2g / L~4g / L.

[0024] According to one aspect of this disclosure, a nickel-cobalt hydroxide product is provided, which is prepared by the method described above for precipitating nickel-cobalt in a nickel-cobalt-containing solution.

[0025] One optional technical solution is that the D50 particle size of the above-mentioned nickel-cobalt hydroxide product is 20μm to 60μm, the water content is 45% to 55%, the nickel content is 39% to 44%, the manganese content is 2% to 4%, and the magnesium content is 0.05% to 1.0%.

[0026] By applying the technical solution of this disclosure, a method for precipitating nickel and cobalt in a nickel-cobalt-containing solution and a nickel-cobalt hydroxide product are provided. This disclosure effectively solves the problems of poor environmental friendliness, small particle size of nickel-cobalt hydroxide making it difficult to settle, high moisture content in filter cake, or poor precipitation rate in the prior art when precipitating nickel and cobalt in laterite nickel ore acid leaching solution for removing iron and aluminum. Using the above-mentioned nickel-cobalt precipitation method, the auxiliary agent used is more environmentally friendly, the precipitation rate is high, and the nickel-cobalt hydroxide has a better morphology, larger particle size, and good settling ability, which is beneficial to subsequent liquid-solid separation processes, thus also reducing the moisture content of the nickel-cobalt hydroxide product.

[0027] To achieve the foregoing and related objectives, one or more aspects of this disclosure include features that will be described in detail below and specifically pointed out in the claims. The following description and accompanying drawings illustrate certain exemplary aspects of this disclosure. However, these aspects indicate only a few of the various ways in which the principles of this disclosure can be applied. Furthermore, this disclosure is intended to include all such aspects and their equivalents. Attached Figure Description

[0028] Other objects and results of this disclosure will become more apparent and readily understood upon reference to the following description taken in conjunction with the accompanying drawings and the claims, and with a more complete understanding of this disclosure. The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute an undue limitation of this disclosure. In the drawings:

[0029] Figure 1 shows a process flow diagram of a method for precipitating nickel and cobalt in a nickel-cobalt-containing solution according to an embodiment of the present disclosure;

[0030] Figure 2 shows a process flow diagram of a method for precipitating nickel-cobalt in a nickel-cobalt-containing solution according to another embodiment of the present disclosure.

[0031] In all the accompanying drawings, the same reference numerals indicate similar or corresponding features or functions. Detailed Implementation

[0032] 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 the embodiments and features described herein can be combined with each other without conflict; these embodiments can 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.

[0033] The specific embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0034] As described in the background section, the prior art for precipitating nickel and cobalt in laterite nickel ore acid leaching solution for removing iron and aluminum has poor environmental performance, small nickel and cobalt hydroxide particle size, high filter cake moisture content, or low precipitation rate. In order to solve the above problems, this disclosure provides a method for precipitating nickel and cobalt in a nickel and cobalt-containing solution and a nickel and cobalt hydroxide product.

[0035] In a typical embodiment of this disclosure, a method for precipitating nickel and cobalt in a nickel-cobalt-containing solution is provided. The cations in the nickel-cobalt-containing solution include nickel ions, cobalt ions, magnesium ions, and manganese ions. As shown in Figures 1 and 2, the method includes: step S100, using a first nickel-cobalt precipitation underflow to perform a seed crystal pretreatment reaction on the nickel-cobalt-containing solution to form a pretreated nickel-cobalt slurry; step S200, adding an alkaline precipitation inducer to a second nickel-cobalt precipitation underflow to perform an alkaline conversion reaction to form an alkaline conversion slurry; or, adding an alkaline precipitation inducer to the first nickel-cobalt precipitation overflow to perform an alkaline conversion reaction. In step S300, the pretreated nickel-cobalt slurry and the alkali-converted slurry are continuously fed into a reactor for nickel-cobalt precipitation reaction to obtain nickel-cobalt precipitated slurry. In step S400, the nickel-cobalt precipitated slurry is continuously subjected to thickening separation treatment to obtain nickel-cobalt precipitate underflow and nickel-cobalt precipitate overflow. The nickel-cobalt precipitate underflow consists of a first nickel-cobalt precipitate underflow, a second nickel-cobalt precipitate underflow, and a third nickel-cobalt precipitate underflow. The nickel-cobalt precipitate overflow includes the first nickel-cobalt precipitate overflow. In step S500, the third nickel-cobalt precipitate underflow is sequentially filtered and washed to obtain nickel-cobalt hydroxide product.

[0036] The method for precipitating nickel-cobalt in this disclosure includes adding a first nickel-cobalt precipitate underflow to a nickel-cobalt-containing solution for a seed crystal pretreatment reaction. This involves pre-mixing a portion of the nickel-cobalt hydroxide precipitate as a seed crystal with the nickel-cobalt-containing solution, thereby allowing the magnesium and manganese in the nickel-cobalt hydroxide precipitate to undergo a thorough replacement reaction with the nickel and cobalt in the nickel-cobalt-containing solution. This process significantly removes the manganese and magnesium from the nickel-cobalt hydroxide precipitate, promotes the aggregation and precipitation of nickel and cobalt ions in the solution, forms a larger and more stable precipitate structure, improves the particle size and settling properties of the precipitate, and ultimately obtains a higher quality nickel-cobalt hydroxide product.

[0037] After the magnesium and manganese in the nickel-cobalt hydroxide precipitate have fully undergone a displacement reaction with the nickel and cobalt in the nickel-cobalt solution, the pretreated nickel-cobalt ore slurry and the alkali-converting slurry are continuously fed into the reactor for nickel-cobalt precipitation. In this process, unlike traditional precipitation reactions, this disclosure does not use strong alkalis such as sulfides or sodium hydroxide, nor does it directly use magnesium hydroxide, which has low activity. The precipitant used in this disclosure is the alkali-converting slurry formed after the second nickel-cobalt precipitation underflow or the first nickel-cobalt precipitation overflow undergoes an alkali-converting reaction with an alkaline precipitation inducer. As mentioned above, it is obtained by reacting the second nickel-cobalt precipitation underflow or the first nickel-cobalt precipitation overflow obtained from the continuous precipitation reaction with an alkaline precipitation inducer through an alkali-converting reaction. Specifically, an alkaline precipitation inducer is added to a portion of the overflow obtained in the previous process (i.e., the first nickel-cobalt precipitation overflow) to undergo an alkali-converting reaction to obtain the alkali-converting slurry; or, an alkaline precipitation inducer is added to a portion of the underflow obtained in the previous process (i.e., the second nickel-cobalt precipitation underflow) to undergo an alkali-converting reaction to form the alkali-converting slurry.

[0038] As mentioned earlier, the nickel-cobalt solution contains not only nickel and cobalt ions to be precipitated, but also a large amount of magnesium and divalent manganese ions. Correspondingly, the nickel-cobalt precipitate underflow and overflow generated in the previous process also contain a large amount of magnesium and divalent manganese ions. Adding an alkaline precipitation inducer to the second nickel-cobalt precipitate underflow or the first nickel-cobalt precipitate overflow can convert these magnesium and divalent manganese ions into magnesium hydroxide and manganese hydroxide. Furthermore, since this disclosure utilizes an alkaline precipitation inducer to prepare the alkaline slurry online during continuous alkaline precipitation and continuous concentration separation, the highly active alkaline slurry can be promptly returned to the previous process to participate in the nickel-cobalt precipitation reaction, ensuring that the alkaline slurry has high precipitation activity. In addition, the alkaline slurry also contains a portion of nickel-cobalt hydroxide generated in the previous process (from the second nickel-cobalt precipitate underflow), which can also act as a seed template during the nickel-cobalt precipitation reaction, promoting the precipitation and crystal growth of nickel-cobalt hydroxide.

[0039] Based on the above reasons, this disclosure effectively solves the problems of small particle size of nickel-cobalt hydroxide, high moisture content in filter cake, poor precipitation rate, and high magnesium content in the prior art when precipitating nickel-cobalt in nickel-cobalt solutions. The method for precipitating nickel-cobalt in nickel-cobalt solutions described above uses more environmentally friendly additives, achieves a high precipitation rate, and produces nickel-cobalt hydroxide products with better morphology, larger particle size, and good sedimentation ability, which is beneficial for subsequent liquid-solid separation processes. This also reduces the moisture content of the nickel-cobalt hydroxide product, while the resulting nickel-cobalt hydroxide product has lower magnesium and manganese ion content.

[0040] In a preferred embodiment, in order to maintain better precipitation activity of the alkali-converting slurry and prevent it from aging after long-term storage, the alkali-converting slurry is placed in step S300 within 5 minutes, more preferably within 3 minutes, to participate in the nickel-cobalt precipitation reaction.

[0041] In one embodiment of this disclosure, in step S100 above, the temperature of the seed crystal pretreatment reaction is 25°C to 100°C, preferably 50°C to 80°C, and the time of the seed crystal pretreatment reaction is 0.1h to 10h, preferably 1h to 5h.

[0042] The optimal reaction temperature range ensures the rate and conversion of the seed crystal pretreatment reaction, enabling nickel-cobalt ions to precipitate rapidly and efficiently on the seed crystal surface, forming precipitates with larger particle sizes. This improves the efficiency and quality of nickel-cobalt precipitation while reducing energy consumption. The seed crystal pretreatment reaction temperature can be 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, or 100℃, and is not limited to any value within the range of 25℃ to 100℃. The seed crystal pretreatment reaction time can be 0.1h, 1h, 1.5h, 2h, 3h, 4h, 5h, 6h, 8h, 9h, or 10h, and is not limited to any value within the range of 0.1h to 10h.

[0043] In one embodiment of this disclosure, in step S100 above, the mass of the first nickel-cobalt precipitate underflow is 0.1% to 99% of the total mass of the nickel-cobalt precipitate underflow.

[0044] The ratio of the mass of the first nickel-cobalt precipitate underflow to the total mass of the nickel-cobalt precipitate underflow directly affects the effectiveness of the seed crystal pretreatment reaction. An appropriate amount of the first nickel-cobalt precipitate underflow can promote seed crystal formation and precipitate growth, and improve the sedimentation performance of the precipitate. By adjusting the proportion of the first nickel-cobalt precipitate underflow in the total mass of the nickel-cobalt precipitate underflow, the precipitation process can be optimized, precipitation efficiency can be improved, and the flexibility of the process can be ensured to adapt to nickel-cobalt solutions of different concentrations. The mass of the first nickel-cobalt precipitate underflow can be 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, 28%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 70%, 80%, 90%, or 99% of the total mass of the nickel-cobalt precipitate underflow, and is not limited to any value between 0.1% and 99%.

[0045] The aforementioned alkaline precipitation inducer is added in the form of an aqueous solution or slurry. To make the alkali conversion reaction more stable and the resulting alkali-converted crystal slurry more active, in a preferred embodiment, the total mass concentration of the alkaline precipitation inducer in step S200 is 0.1% to 60%, preferably 3% to 20%, and more preferably 3% to 15%. Controlling its concentration within this range ensures a more stable alkali conversion reaction and a more suitable concentration of the alkali-converted crystal slurry, thereby promoting a more efficient and stable nickel-cobalt precipitation reaction. Specifically, the concentration of the alkaline precipitation inducer directly affects the pH value of the solution. Selecting a reasonable concentration range helps promote the effective precipitation of nickel and cobalt, avoids the co-precipitation of other impurity ions, improves the efficiency of nickel-cobalt precipitation, thereby increasing product purity, while controlling costs and reducing environmental impact. The total mass concentration of the alkaline precipitation inducer can be 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, 28%, 30%, 35%, 40%, 45%, 50%, 55%, or 60%, and is not limited to any value between 0.1% and 60%.

[0046] In a preferred embodiment, in step S200 above, the alkaline precipitation inducer is a mixture of an alkaline substance and an aqueous solution, wherein the alkaline substance is selected from any one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide, and carbonates.

[0047] Using the above-mentioned precipitation inducer, the precipitation activity of the alkali crystal slurry is more suitable, which can not only make nickel and cobalt precipitate more stably, but also make the nickel and cobalt hydroxide precipitate particles have better morphology, making liquid-solid separation easier, and the final product has lower water content and lower manganese content.

[0048] Furthermore, in step S200 above, the alkaline substance is preferably a mixture of sodium hydroxide and potassium hydroxide, and the mass ratio of sodium hydroxide to potassium hydroxide is (1-4):(1-4). Compared with other alkaline precipitation inducers such as calcium oxide, calcium hydroxide, or sodium hydroxide, the compound precipitation inducer with the above weight ratio produces a better alkali-converting slurry. Combined with a seed template, it has a better promoting effect on improving the morphology, precipitation rate, and particle size of nickel-cobalt hydroxide during the alkali-converting precipitation process. The mass ratio of sodium hydroxide to potassium hydroxide can be 1:1, 1:4, 1:2, or 4:1, and is not limited to any one of the mass ratios of (1-4):(1-4).

[0049] To ensure more thorough precipitation of nickel and cobalt ions in the mixed solution, in a preferred embodiment, the total number of hydroxide and / or carbonate ions in the alkaline precipitation inducer is 0.5 to 1.5 times the theoretical total number of moles required for nickel-cobalt precipitation in the pretreated nickel-cobalt slurry. In actual operation, to further reduce the impurity content in the nickel-cobalt hydroxide product, such as magnesium and manganese, the number of hydroxide ions in the precipitation inducer is preferably 0.8 to 0.9 times the theoretical total number of moles. This operation may result in a slight loss of direct nickel-cobalt hydroxide recovery, but the product is purer.

[0050] In one embodiment of this disclosure, in step S200 above, the temperature of the alkali conversion reaction is 25°C to 100°C, preferably 50°C to 60°C, and the time of the alkali conversion reaction is 0.1 min to 30 min, preferably 1 min to 10 min, and more preferably 3 min to 5 min.

[0051] Based on the kinetics of the alkali conversion reaction, controlling the temperature and time of the reaction within the above range helps to ensure the reaction proceeds under suitable conditions, improving the efficiency and quality of nickel-cobalt precipitation while reducing energy consumption. The temperature of the alkali conversion reaction can be 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, or 100℃, but is not limited to any value within the range of 25℃ to 100℃. The reaction time can be 0.1 min, 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 8 min, 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, 23 min, 25 min, 28 min, or 30 min, but is not limited to any value within the range of 0.1 min to 30 min.

[0052] In one embodiment of this disclosure, in step S200 above, the mass of the first nickel-cobalt precipitate overflow is 1% to 99% of the total mass of the nickel-cobalt precipitate overflow, preferably 5% to 30%.

[0053] The control of the first nickel-cobalt precipitate overflow is based on considerations of the material balance in the precipitation process. An appropriate amount of first nickel-cobalt precipitate overflow helps maintain the growth and settling of the precipitate; too much or too little overflow will affect the precipitation effect. Adjusting the mass ratio of the first nickel-cobalt precipitate overflow in the total nickel-cobalt precipitate overflow helps optimize the nickel-cobalt precipitation process, improve the nickel-cobalt precipitation efficiency, and simultaneously achieve the flexibility and stability of the nickel-cobalt precipitation process, adapting to solutions containing nickel-cobalt of different concentrations. The mass of the first nickel-cobalt precipitate overflow can be 1%, 2%, 3%, 4%, 5%, 6%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, 28%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 70%, 80%, 90%, or 99% of the total mass of the nickel-cobalt precipitate overflow, but is not limited to any value between 1% and 99%.

[0054] In one embodiment of this disclosure, in step S200 above, the mass of the second nickel-cobalt precipitate underflow is 1% to 99% of the total mass of the nickel-cobalt precipitate underflow.

[0055] By controlling the mass percentage of the second nickel-cobalt precipitation underflow in the total nickel-cobalt precipitation underflow, it is beneficial to optimize the nickel-cobalt precipitation process, improve precipitation efficiency and product quality, and ensure the flexibility and stability of the precipitation process to adapt to solutions containing nickel-cobalt of different concentrations. The mass of the second nickel-cobalt precipitation underflow can be 1%, 2%, 3%, 4%, 5%, 6%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, 28%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 70%, 80%, 90%, or 99% of the total mass of the nickel-cobalt precipitation underflow, and is not limited to any value between 1% and 99%.

[0056] The active components of the alkali-converting slurry are mainly nickel-cobalt hydroxide, magnesium hydroxide, and manganese hydroxide. To enhance the precipitation activity of the slurry, in a preferred embodiment, when an alkaline precipitation inducer is added to the first nickel-cobalt precipitate overflow to initiate the alkali-converting reaction and form the slurry, the mass ratio of the first, second, and third nickel-cobalt precipitate underflows is (55%–89%):(10%–40%):(1%–5%). Adjusting the mass ratio of these three underflows helps optimize the precipitation process, maintains the optimal growth state of the precipitate, optimizes its settling performance, improves precipitation efficiency and product quality, and ensures process stability and operability. The mass ratio of the first nickel-cobalt precipitation undercurrent, the second nickel-cobalt precipitation undercurrent, and the third nickel-cobalt precipitation undercurrent can be 85%:10%:5%, 55%:40%:5%, or 65%:30%:5%, and is not limited to any one of the values ​​in (55%~89%):(10%~40%):(1%~5%).

[0057] In practice, the third nickel-cobalt precipitate underflow can be directly filtered and washed to obtain nickel-cobalt hydroxide product with a low manganese content. When the first nickel-cobalt precipitate overflow participates in the alkali conversion reaction, the remaining nickel-cobalt precipitate overflow can be directly used for the second-stage nickel-cobalt precipitation. When the nickel-cobalt precipitate overflow does not participate in the alkali conversion reaction, it can be directly discharged for the second-stage nickel-cobalt precipitation (such as returning it to the high-pressure acid leaching process of laterite nickel ore or other upstream processes).

[0058] To ensure a more complete conversion of magnesium and divalent manganese ions in the underflow of the second nickel-cobalt precipitation or the overflow of the first nickel-cobalt precipitation, in a preferred embodiment, the temperature of the nickel-cobalt precipitation reaction is 50°C to 70°C, and the reaction time is 0.5 h to 5 h. Under these process conditions, the resulting alkali-converted slurry exhibits better nickel-cobalt precipitation activity and a higher nickel-cobalt precipitation rate, reducing resource waste and better promoting the nickel-cobalt precipitation process in the mixed solution. By optimizing the precipitation conditions, including using seed crystal pretreatment and controlling the concentration and composition of the alkaline precipitation inducer, the precipitation rate of nickel-cobalt ions and the stability of the precipitate can be improved, thereby achieving a nickel-cobalt precipitation rate of 70% to 98%. The temperature of the nickel-cobalt precipitation reaction can be 50°C, 55°C, 60°C, 65°C, or 70°C, and is not limited to any value within the range of 50°C to 70°C. The reaction time for nickel-cobalt precipitation can be 0.5h, 1h, 1.2h, 1.5h, 1.8h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, or 5h, and is not limited to any value within the range of 0.5h to 5h. The nickel-cobalt precipitation rate in the reaction can be 70%, 72%, 74%, 76%, 78%, 80%, 82%, 83%, 85%, 86%, 87%, 88%, 90%, 95%, or 98%, and is not limited to any value within the range of 70% to 98%.

[0059] The method for precipitating nickel and cobalt provided in this disclosure can be carried out continuously. Fresh nickel-cobalt-containing solutions (such as acid leaching solutions for removing iron and aluminum from laterite nickel ore) are continuously fed into the seed crystal pretreatment reaction, and then continuously fed into the reactor to react with the alkali-converted slurry returned from the subsequent process for nickel-cobalt precipitation. The resulting precipitated slurry continuously enters the liquid-solid separation stage to form underflow and overflow. Part of the underflow and optional part of the overflow continue to participate in the alkali-converted reaction, and continuously form alkali-converted slurry which is returned to the previous process to participate in the nickel-cobalt precipitation reaction. In the initial stage of operation, the mixed solution can be precipitated with sodium hydroxide first. After the initial underflow and overflow are formed, the alkali-converted slurry of this disclosure is prepared using the preparation process described above as a precipitant after the operation is stabilized.

[0060] The precipitation method disclosed herein is applicable to nickel-cobalt solutions, such as nickel-cobalt precipitation in laterite nickel ore acid leaching solutions for removing iron and aluminum. It is particularly suitable for solutions containing the following cationic components: nickel ions 0.1 g / L–120 g / L, cobalt ions 0.1 g / L–120 g / L, magnesium ions 0.5 g / L–25 g / L, and divalent manganese ions 0.5 g / L–10 g / L. More preferably, nickel ions 3 g / L–5 g / L, cobalt ions 0.2 g / L–0.5 g / L, magnesium ions 5 g / L–8 g / L, and divalent manganese ions 2 g / L–4 g / L. By controlling the concentration range of metal ions in the solution, combined with seed crystal pretreatment and alkali conversion reaction, precipitation conditions can be optimized, achieving effective separation and recovery of nickel and cobalt, and reducing the risk of co-precipitation of impurities such as magnesium and manganese.

[0061] According to one aspect of this disclosure, a nickel-cobalt hydroxide product is provided, which is prepared by the method described above for precipitating nickel-cobalt in a nickel-cobalt-containing solution.

[0062] The nickel-cobalt hydroxide product prepared by the above method has an optimized nickel-cobalt precipitation process, avoiding the co-precipitation of other impurities, thereby ensuring the high purity and high nickel-cobalt content of the product, making it more suitable for battery materials and other industrial applications.

[0063] In one embodiment of this disclosure, the D50 particle size of the above-mentioned nickel-cobalt hydroxide product is 20 μm to 60 μm, the water content is 45% to 55%, the nickel content is 39% to 44%, the manganese content is 2% to 4%, and the magnesium content is 0.05% to 1.0%.

[0064] The nickel-cobalt hydroxide product disclosed herein has a moderate D50 particle size and moisture content, a nickel content as high as 39% to 44%, a manganese content of no more than 4%, and a magnesium content of no more than 1.0%. These characteristics give it good settling and filter cake properties, making it suitable for the needs of battery materials and other industrial applications.

[0065] The present disclosure will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed by the present disclosure.

[0066] The following examples illustrate the treatment of an acid leaching solution (aqueous solution) for removing iron and aluminum from laterite nickel ore. The anion in this solution is sulfate ion, and the cation composition is as follows:

[0067] Example 1

[0068] Referring to the process flow diagram of the method for precipitating nickel and cobalt in a nickel-cobalt solution shown in Figure 1, the first nickel-cobalt precipitation underflow (i.e., the underflow after nickel-cobalt precipitation, which accounts for 85% of the total nickel-cobalt precipitation underflow in the downstream process) is added to the above laterite nickel ore acid leaching solution for removing iron and aluminum. The mixture is stirred and mixed at 70°C for 3.0 h to complete the seed crystal pretreatment reaction and form a pretreated nickel-cobalt ore slurry.

[0069] The pretreated nickel-cobalt ore slurry and the alkali-converting slurry prepared in the downstream process were continuously convectively added to a reactor for nickel-cobalt precipitation reaction. The reaction time was 3.0 h and the reaction temperature was 60 °C, resulting in a nickel-cobalt precipitated ore slurry. The nickel-cobalt precipitated ore slurry was then continuously fed into a thickener for thickening and separation, yielding a nickel-cobalt precipitate underflow and a nickel-cobalt precipitate overflow. The nickel-cobalt precipitate underflow consists of a first nickel-cobalt precipitate underflow, a second nickel-cobalt precipitate underflow, and a third nickel-cobalt precipitate underflow. The third nickel-cobalt precipitate underflow was filtered and washed to obtain nickel-cobalt hydroxide product.

[0070] A 20% (w / w) alkaline precipitation inducer, formed by dissolving sodium hydroxide and potassium hydroxide in water at a mass ratio of 4:4, was prepared. A second nickel-cobalt precipitation underflow, comprising 10% of the nickel-cobalt precipitation underflow, was continuously fed into an alkali-converting reactor. The alkaline precipitation inducer was added to initiate the alkali-converting reaction. Based on the theoretical molar number of hydroxide ions required for nickel-cobalt precipitation in the mixed solution, the number of hydroxide ions in the precipitation inducer was 0.9 times the theoretical molar number. The alkali-converting reaction was conducted at 50°C for 3 minutes, yielding an alkali-converted slurry. This alkali-converted slurry was continuously returned to the nickel-cobalt precipitation reaction step to obtain the post-precipitated nickel-cobalt slurry.

[0071] Testing revealed that the nickel-cobalt precipitation rate in the nickel-cobalt precipitation reaction was 85%, the D50 particle size of the nickel-cobalt hydroxide product was 45–55 μm, the water content was 55%, the nickel content was 43%, the manganese content was 2%, and the magnesium content was 0.1%.

[0072] Example 2

[0073] Referring to the process flow diagram of the method for precipitating nickel and cobalt in a nickel-cobalt solution shown in Figure 2, 30% of the nickel-cobalt precipitation bottom flow from the downstream process is added to the above laterite nickel ore acid leaching solution for removing iron and aluminum. The mixture is stirred and mixed at 40°C for 10.0 h to complete the seed crystal pretreatment reaction and form a pretreated nickel-cobalt ore slurry.

[0074] Pretreated nickel-cobalt ore slurry and alkali-converted crystal slurry prepared in the downstream process are continuously convectively added to a reactor for nickel-cobalt precipitation reaction. The reaction time is 1.0 h, and the reaction temperature is 70℃, yielding a nickel-cobalt precipitated ore slurry. The precipitated ore slurry is then continuously fed into a thickener for thickening and separation, yielding a nickel-cobalt precipitate underflow and a nickel-cobalt precipitate overflow. The nickel-cobalt precipitate underflow consists of a first nickel-cobalt precipitate underflow, a second nickel-cobalt precipitate underflow, and a third nickel-cobalt precipitate underflow, with the second nickel-cobalt precipitate underflow accounting for 0% of the total nickel-cobalt precipitate underflow. The third nickel-cobalt precipitate underflow is filtered and washed to obtain nickel-cobalt hydroxide product.

[0075] A 20% (w / w) alkaline precipitation inducer was prepared, consisting of sodium hydroxide and potassium hydroxide dissolved in water at a 4:4 (w / w) ratio. The first nickel-cobalt precipitate overflow (10% of the total nickel-cobalt precipitate overflow) was continuously fed into the alkali conversion reactor. The alkaline precipitation inducer was added to initiate the alkali conversion reaction. Based on the theoretical molar number of hydroxide ions required for nickel-cobalt precipitation in the mixed solution, the number of hydroxide ions in the precipitation inducer was 0.9 times the theoretical molar number. The alkali conversion reaction was conducted at 50°C for 3 minutes, yielding an alkali-converted slurry. This alkali-converted slurry was continuously returned to the nickel-cobalt precipitation reaction step to obtain the post-precipitated nickel-cobalt slurry.

[0076] Tests showed that the nickel-cobalt precipitation rate in the nickel-cobalt precipitation reaction was 86%, the D50 particle size of the nickel-cobalt hydroxide product was 45-55 μm, the water content was 54%, the nickel content was 44%, the manganese content was 2.2%, and the magnesium content was 0.15%.

[0077] Example 3

[0078] The only difference between this embodiment and Example 1 is that sodium hydroxide and potassium hydroxide are mixed in a mass ratio of 1:4, the total mass concentration of the precipitation inducer is 25%, and the final product is nickel-cobalt hydroxide.

[0079] Testing revealed that the nickel-cobalt precipitation rate in the nickel-cobalt precipitation reaction was 85%, the D50 particle size of the nickel-cobalt hydroxide product was 45–50 μm, the water content was 56%, the nickel content was 43%, the manganese content was 2%, and the magnesium content was 0.1%.

[0080] Example 4

[0081] The only difference between this embodiment and Example 1 is that sodium hydroxide and potassium hydroxide are mixed in a mass ratio of 0.6:4 to obtain nickel-cobalt hydroxide product.

[0082] Testing revealed that the nickel-cobalt precipitation rate in the nickel-cobalt precipitation reaction was 85%, the D50 particle size of the nickel-cobalt hydroxide product was 40–45 μm, the water content was 58%, the nickel content was 43%, the manganese content was 2%, and the magnesium content was 0.1%.

[0083] Example 5

[0084] The only difference between this embodiment and Example 1 is that the precipitation inducer is magnesium oxide with a mass concentration of 10%, and the final product is nickel-cobalt hydroxide.

[0085] Tests showed that the nickel-cobalt precipitation rate in the nickel-cobalt precipitation reaction was 85%, the D50 particle size of the nickel-cobalt hydroxide product was 45-55 μm, the water content was 53%, the nickel content was 41%, the manganese content was 3%, and the magnesium content was 0.5%.

[0086] Example 6

[0087] The difference between this embodiment and Embodiment 1 is that the first nickel-cobalt precipitate underflow accounts for 55% of the total nickel-cobalt precipitate underflow, and the mass ratio of the first nickel-cobalt precipitate underflow, the second nickel-cobalt precipitate underflow, and the third nickel-cobalt precipitate underflow is 55:40:5, ultimately yielding nickel-cobalt hydroxide product.

[0088] Tests showed that the nickel-cobalt precipitation rate in the nickel-cobalt precipitation reaction was 85%, the D50 particle size of the nickel-cobalt hydroxide product was 45-55 μm, the water content was 55%, the nickel content was 43%, the manganese content was 3%, and the magnesium content was 0.4%.

[0089] Example 7

[0090] The difference between this embodiment and Embodiment 1 is that the first nickel-cobalt precipitate underflow accounts for 90% of the total nickel-cobalt precipitate underflow, and the mass ratio of the first nickel-cobalt precipitate underflow, the second nickel-cobalt precipitate underflow, and the third nickel-cobalt precipitate underflow is 90:5:5, ultimately obtaining the nickel-cobalt hydroxide product.

[0091] Testing revealed that the nickel-cobalt precipitation rate in the nickel-cobalt precipitation reaction was 85%, the D50 particle size of the nickel-cobalt hydroxide product was 20–25 μm, the water content was 65%, the nickel content was 43%, the manganese content was 2%, and the magnesium content was 0.1%.

[0092] Example 8

[0093] The difference between this embodiment and Embodiment 1 is that the temperature of the seed crystal pretreatment reaction is 80°C and the reaction time is 5 hours, ultimately yielding nickel-cobalt hydroxide product.

[0094] Tests showed that the nickel-cobalt precipitation rate in the nickel-cobalt precipitation reaction was 85%, the D50 particle size of the nickel-cobalt hydroxide product was 45-55 μm, the water content was 55%, the nickel content was 44%, the manganese content was 1.5%, and the magnesium content was 0.05%.

[0095] Example 9

[0096] The difference between this embodiment and Example 1 is that the temperature of the alkali conversion reaction is 40°C and the reaction time is 10 minutes, ultimately yielding nickel-cobalt hydroxide product.

[0097] Testing revealed that the nickel-cobalt precipitation rate in the nickel-cobalt precipitation reaction was 78%, the D50 particle size of the nickel-cobalt hydroxide product was 45–55 μm, the water content was 52%, the nickel content was 39%, the manganese content was 4%, and the magnesium content was 0.8%.

[0098] Example 10

[0099] The difference between this embodiment and Example 1 is that the temperature of the nickel-cobalt precipitation reaction is 50°C and the reaction time is 5 hours, ultimately yielding nickel-cobalt hydroxide product.

[0100] Tests showed that the nickel-cobalt precipitation rate in the nickel-cobalt precipitation reaction was 83%, the D50 particle size of the nickel-cobalt hydroxide product was 40-53 μm, the water content was 56%, the nickel content was 42%, the manganese content was 4%, and the magnesium content was 1%.

[0101] Example 11

[0102] The difference between this embodiment and Example 1 is that, based on the theoretical number of hydroxide ions required for nickel-cobalt precipitation in the mixed solution, the number of hydroxide ions in the alkaline precipitation inducer is 0.8 times the theoretical number of hydroxide ions.

[0103] Tests showed that the nickel-cobalt precipitation rate in the nickel-cobalt precipitation reaction was 80%, the D50 particle size of the nickel-cobalt hydroxide product was 45-55 μm, the water content was 54%, the nickel content was 43.1%, the manganese content was 2.1%, and the magnesium content was 0.12%.

[0104] Example 12

[0105] The difference between this embodiment and Example 1 is that, based on the theoretical number of hydroxide ions required for nickel-cobalt precipitation in the mixed solution, the number of hydroxide ions in the alkaline precipitation inducer is 1.2 times the theoretical number of hydroxide ions.

[0106] Tests showed that the nickel-cobalt precipitation rate in the nickel-cobalt precipitation reaction was 98%, the D50 particle size of the nickel-cobalt hydroxide product was 45-55 μm, the water content was 55%, the nickel content was 41%, the manganese content was 4%, and the magnesium content was 1%.

[0107] Example 13

[0108] The difference between this embodiment and Embodiment 1 is that the alkali crystal slurry is continuously returned to the nickel-cobalt precipitation reaction step within 5 minutes to carry out the nickel-cobalt precipitation reaction.

[0109] Tests showed that the nickel-cobalt precipitation rate in the nickel-cobalt precipitation reaction was 83%, the D50 particle size of the nickel-cobalt hydroxide product was 55-60 μm, the water content was 53%, the nickel content was 42%, the manganese content was 2.5%, and the magnesium content was 0.4%.

[0110] Comparative Example 1

[0111] Add the first nickel-cobalt precipitation underflow (i.e., the underflow after nickel-cobalt precipitation, which accounts for 30% of the total nickel-cobalt precipitation underflow in the downstream process) to the above laterite nickel ore acid leaching solution for removing iron and aluminum, and stir and mix at 70°C for 3.0 h to complete the seed crystal pretreatment reaction and form the pretreated nickel-cobalt ore slurry.

[0112] Pretreated nickel-cobalt ore slurry was continuously added to a reactor via convection with a pre-prepared 20% sodium hydroxide aqueous solution to directly carry out the nickel-cobalt precipitation reaction. The reaction time was 3.0 h, and the reaction temperature was 60℃, yielding a nickel-cobalt precipitated ore slurry. This precipitated ore slurry was then continuously fed into a thickener for thickening and separation, yielding a nickel-cobalt precipitate underflow and a nickel-cobalt precipitate overflow. The nickel-cobalt precipitate underflow consists of a first nickel-cobalt precipitate underflow, a second nickel-cobalt precipitate underflow, and a third nickel-cobalt precipitate underflow. The third nickel-cobalt precipitate underflow was filtered and washed to obtain nickel-cobalt hydroxide product.

[0113] Tests showed that the nickel-cobalt precipitation rate in the nickel-cobalt precipitation reaction was 85%, the D50 particle size of the nickel-cobalt hydroxide product was 3-5 μm, the water content was 75%, the nickel content was 36%, the manganese content was 5%, and the magnesium content was 1.2%.

[0114] Comparative Example 2

[0115] The acid leaching solution for removing iron and aluminum from laterite nickel ore and the alkali-converting slurry prepared in the downstream process are continuously added to the reactor via convection to directly carry out the nickel-cobalt precipitation reaction. The reaction time is 3.0 h and the reaction temperature is 60℃, resulting in a nickel-cobalt precipitated slurry. The nickel-cobalt precipitated slurry is then continuously fed into a thickener for thickening and separation, yielding a nickel-cobalt precipitate underflow and a nickel-cobalt precipitate overflow. The nickel-cobalt precipitate underflow consists of a first nickel-cobalt precipitate underflow, a second nickel-cobalt precipitate underflow, and a third nickel-cobalt precipitate underflow. The third nickel-cobalt precipitate underflow is filtered and washed to obtain nickel-cobalt hydroxide product.

[0116] A 20% (w / w) alkaline precipitation inducer was prepared, consisting of sodium hydroxide and potassium hydroxide dissolved in water at a 4:4 (w / w) ratio. A second nickel-cobalt precipitate underflow, comprising 5% of the nickel-cobalt precipitate underflow, was continuously fed into an alkali-converting reactor. The alkaline precipitation inducer was added to initiate the alkali-converting reaction. The alkali-converting slurry contained in the precipitation inducer was 0.9 times the theoretical molar number of hydroxide ions required for nickel-cobalt precipitation in the mixed solution. The alkali-converting reaction was conducted at 70°C for 1 minute, yielding an alkali-converted slurry. This alkali-converted slurry was continuously returned to the nickel-cobalt precipitation reaction step to obtain the post-precipitated nickel-cobalt slurry.

[0117] Tests showed that the nickel-cobalt precipitation rate in the nickel-cobalt precipitation reaction was 89%, the D50 particle size of the nickel-cobalt hydroxide product was 45-55 μm, the water content was 55%, the nickel content was 39%, the manganese content was 7%, and the magnesium content was 2.5%.

[0118] As can be seen from the above description, the embodiments of this disclosure achieve the following technical effects:

[0119] The method for precipitating nickel-cobalt in this disclosure includes adding a first nickel-cobalt precipitate underflow to a nickel-cobalt-containing solution for a seed crystal pretreatment reaction. This involves pre-mixing a portion of the nickel-cobalt hydroxide precipitate as a seed crystal with the nickel-cobalt-containing solution, thereby allowing the magnesium and manganese in the nickel-cobalt hydroxide precipitate to undergo a thorough replacement reaction with the nickel and cobalt in the nickel-cobalt-containing solution. This process significantly removes the manganese and magnesium from the nickel-cobalt hydroxide precipitate, promotes the aggregation and precipitation of nickel and cobalt ions in the solution, forms a larger and more stable precipitate structure, improves the particle size and settling properties of the precipitate, and ultimately obtains a higher quality nickel-cobalt hydroxide product.

[0120] The above are merely preferred embodiments of this disclosure and are not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A method for precipitating nickel and cobalt from a nickel and cobalt containing solution, the cations in the nickel and cobalt containing solution comprising nickel ions, cobalt ions, magnesium ions and manganese ions, characterized in that, The method comprises: In step S100, seed pretreatment reaction is performed on the nickel-cobalt-containing solution by using a first nickel-cobalt precipitation underflow to form a pretreated nickel-cobalt ore slurry; In step S200, an alkaline precipitation inducer is added to a second nickel-cobalt precipitation underflow to perform a base conversion reaction and form a base conversion slurry; or, the alkaline precipitation inducer is added to a first nickel-cobalt precipitation overflow to perform a base conversion reaction and form a base conversion slurry; In step S300, the pretreated nickel-cobalt ore slurry and the base conversion slurry are continuously fed into a reactor to perform a nickel-cobalt precipitation reaction, thereby obtaining a nickel-cobalt precipitated ore slurry; In step S400, the nickel-cobalt precipitated ore slurry is continuously subjected to thickening separation treatment to obtain a nickel-cobalt precipitation underflow and a nickel-cobalt precipitation overflow; the nickel-cobalt precipitation underflow is composed of the first nickel-cobalt precipitation underflow, the second nickel-cobalt precipitation underflow and a third nickel-cobalt precipitation underflow; and the nickel-cobalt precipitation overflow includes the first nickel-cobalt precipitation overflow; In step S500, the third nickel-cobalt precipitation underflow is sequentially subjected to filtration and washing to obtain a nickel-cobalt hydroxide product.

2. The method for precipitating nickel and cobalt from a nickel and cobalt containing solution according to claim 1, characterized in that, In step S100, the seed pretreatment reaction is performed at a temperature of 25-100°C for 0.1-10 hours.

3. The method for precipitating nickel and cobalt from a nickel and cobalt containing solution according to claim 1 or 2, characterized in that, In step S100, the mass of the first nickel-cobalt precipitation underflow accounts for 1-99% of the total mass of the nickel-cobalt precipitation underflow.

4. The method of precipitating nickel and cobalt from a nickel and cobalt containing solution according to claim 1 or 2, characterized in that, In step S200, the total mass concentration of the alkaline precipitation inducer is 0.1-60%.

5. The method of precipitating nickel and cobalt from a nickel and cobalt containing solution according to claim 4, characterized in that, In step S200, the alkaline precipitation inducer is a mixture of an alkaline substance and water, wherein the alkaline substance is selected from any one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide and carbonates.

6. The method of precipitating nickel and cobalt from a nickel and cobalt containing solution according to claim 5, characterized in that, In step S200, the alkaline substance is a mixture of the sodium hydroxide and the potassium hydroxide, and the mass ratio of the sodium hydroxide to the potassium hydroxide is (1-4):(1-4).

7. The method of precipitating nickel and cobalt from a nickel and cobalt containing solution according to claim 1 or 2, characterized in that, The total number of moles of hydroxyl and / or carbonate in the alkaline precipitation inducer is 0.5-1.5 times the total number of moles of hydroxyl and / or carbonate required for nickel-cobalt precipitation in the pretreated nickel-cobalt ore slurry.

8. The method of precipitating nickel and cobalt from a nickel and cobalt containing solution according to claim 1 or 2, characterized in that, In step S200, the base conversion reaction is performed at a temperature of 25-100°C for 0.1-30 minutes.

9. The method of precipitating nickel and cobalt from a nickel and cobalt containing solution according to claim 1 or 2, characterized in that, In step S200, the mass of the first nickel-cobalt precipitation overflow accounts for 1-99% of the total mass of the nickel-cobalt precipitation overflow.

10. The method of precipitating nickel and cobalt from a nickel and cobalt containing solution according to claim 1 or 2, characterized in that, In step S200, the mass of the second nickel-cobalt precipitation underflow accounts for 1-99% of the total mass of nickel-cobalt precipitation underflow.

11. The method of precipitating nickel and cobalt from a nickel and cobalt containing solution according to claim 1 or 2, characterized in that, When the alkaline precipitation inducer is added to the first nickel-cobalt precipitation overflow to perform the base conversion reaction and form the base conversion slurry, the mass ratio of the first nickel-cobalt precipitation underflow, the second nickel-cobalt precipitation underfluid and the third nickel-cobalt precipitation underflow is (55-89):(10-40):(1-5).

12. The method of precipitating nickel and cobalt from a nickel and cobalt containing solution according to claim 1 or 2, characterized in that, The nickel-cobalt precipitation reaction is performed at a temperature of 50-70°C for 0.5-5 hours, and the nickel-cobalt precipitation rate in the nickel-cobalt precipitation reaction is 70-98%.

13. The method of precipitating nickel and cobalt from a nickel and cobalt containing solution according to claim 1 or 2, characterized in that, The cationic components in the nickel-cobalt-containing solution are as follows: nickel ions 0.1-120 g / L, cobalt ions 0.1-120 g / L, magnesium ions 0.5-25 g / L, and divalent manganese ions 0.5-10 g / L.

14. A nickel cobalt hydroxide product, characterized in that, The nickel-cobalt hydroxide product is prepared by the method for precipitating nickel-cobalt from the nickel-cobalt-containing solution according to any one of claims 1-12.

15. The nickel cobalt hydroxide product of claim 14, wherein, The D50 particle size of the nickel-cobalt hydroxide product is 20-60 μm, the water content is 45-55%, the nickel content is 39-44%, the manganese content is 2-4%, and the magnesium content is 0.05-1.0%.

Images