Method for activating magnesium oxide for nickel-cobalt deposition from alkaline solution and nickel-cobalt hydroxide product

Abstract

The application belongs to the technical field of hydrometallurgy, and discloses a method for activating magnesium oxide to precipitate nickel and cobalt in alkaline solution and a nickel cobalt hydroxide product. The method comprises the following steps: activating magnesium oxide by using alkaline solution to obtain activated precipitant slurry; mixing the activated precipitant slurry with free alkali solidification liquid to obtain mixed slurry, wherein the free alkali solidification liquid contains magnesium and manganese elements for solidifying free alkali; adding the mixed slurry into a solution containing nickel and cobalt to carry out nickel and cobalt precipitation reaction, thereby obtaining nickel and cobalt precipitated slurry; and carrying out post-treatment on the nickel and cobalt precipitated slurry to obtain the nickel cobalt hydroxide product. The application can reduce the content of magnesium and chlorine in the nickel cobalt hydroxide product, and can obtain nickel cobalt hydroxide with large particles and low water content, which is beneficial to subsequent processing procedures.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgical technology, specifically to the field of raw material pretreatment technology, and particularly relates to a method for activating magnesium oxide with alkaline solution to precipitate nickel cobalt and a nickel cobalt hydroxide product. Background Technology

[0002] The hydrometallurgical process for laterite nickel ore mainly includes acid leaching, slurry neutralization, neutralization and impurity removal, and nickel-cobalt precipitation. Therefore, the nickel-cobalt precipitation process is performed on the solution after neutralization and impurity removal. In existing technologies, calcium hydroxide and sodium hydroxide are commonly used as precipitants to precipitate nickel and cobalt from the solution to prepare MHP products.

[0003] Furthermore, some literature uses activated magnesium oxide as a precipitant for nickel and cobalt precipitation. However, the inventors of this application have discovered that high-temperature treatment is unavoidable during magnesium oxide preparation, leading to the deactivation of some magnesium oxide. This deactivation results in residues in the product, causing a high magnesium content in the MHP product, which in turn reduces the purity of the MHP product and affects subsequent processing. Moreover, activated magnesium oxide products prepared using the magnesium chloride ammonia method have a high chlorine content. This residual chlorine in the product results in a high chlorine content in the MHP, which is detrimental to subsequent refining processes.

[0004] Based on the above findings, this application proposes a method for recovering nickel and cobalt metal from a solution by activating magnesium oxide precipitation with an alkaline solution. Summary of the Invention

[0005] The purpose of this invention is to provide a method for activating magnesium oxide with an alkaline solution to precipitate nickel cobalt, in order to solve the problem of high magnesium and chlorine content in nickel cobalt hydroxide products.

[0006] The above objective can be achieved through the following technical solutions:

[0007] According to one aspect of the present invention, a method for activating magnesium oxide to precipitate nickel-cobalt using an alkaline solution is provided, comprising:

[0008] Magnesium oxide was activated using an alkaline solution to obtain an activated precipitant slurry;

[0009] The activated precipitant slurry is mixed with a free alkali curing liquid to obtain a mixed slurry; wherein the free alkali curing liquid contains magnesium and manganese elements for curing free alkali;

[0010] The mixed slurry is added to a solution containing nickel and cobalt to carry out a nickel and cobalt precipitation reaction, resulting in a nickel and cobalt precipitated slurry.

[0011] The nickel-cobalt slurry after precipitation is post-processed to obtain nickel-cobalt hydroxide product.

[0012] Preferably, the activation treatment time is 0.5 min to 8 h, and the activation treatment temperature is 25 ° C to 100 ° C.

[0013] Preferably, in the alkaline solution, the amount of alkali added is 0.1% to 99% of the mass of magnesium oxide.

[0014] Preferably, the concentration of the alkaline solution is 0.1% to 40%.

[0015] Preferably, the alkaline solution is at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide, and ammonium hydroxide solutions.

[0016] Preferably, the free alkali curing solution is one or more of the following: slurry after nickel-cobalt precipitation, solution after nickel-cobalt precipitation, and other solutions containing magnesium and manganese ions.

[0017] Preferably, the total molar amount of magnesium and manganese in the free alkali curing liquid is not less than twice the molar amount of hydroxide ions in the activated precipitant slurry.

[0018] Preferably, the molar amount of hydroxide ions in the activating precipitant slurry is 1.5 to 2.5 times the total molar amount of nickel and cobalt to be precipitated.

[0019] Preferably, the mixing time is 0.1 min to 1 h, and the mixing temperature is 25 °C to 100 °C.

[0020] Preferably, the reaction time for the nickel-cobalt immersion reaction is 0.5 h to 8 h, and the reaction temperature is 25 ° C to 100 ° C.

[0021] Preferably, post-processing includes:

[0022] The slurry or the filter cake obtained after pressure filtration and washing is washed; wherein, one or more of methods selected from method one and method two are used for washing treatment, method one is to use a nickel-cobalt containing solution for slurry stirring treatment, and method two is to use an acid solution for acid treatment;

[0023] The washed slurry is filtered to obtain the MHP product; and / or the washed slurry is returned as seed crystals to the nickel-cobalt immersion reaction step.

[0024] Preferably, the washing process takes 0.5 h to 8 h and the temperature is 25℃ to 100℃.

[0025] Preferably, the total nickel and cobalt content in the nickel-cobalt solution is 1 g / L to 100 g / L.

[0026] Preferably, the acid solution is one or more of sulfuric acid, hydrochloric acid, nitric acid, carbonic acid, oxalic acid, and citric acid.

[0027] Preferably, before the washing step, the process further includes: thickening the nickel-cobalt precipitate slurry to obtain a thickened slurry.

[0028] Preferably, the magnesium oxide is active magnesium oxide produced by a chloride system.

[0029] According to one aspect of the present invention, a nickel-cobalt hydroxide product is prepared by the alkaline solution activation method for precipitating nickel-cobalt oxide with magnesium oxide, having a D50 particle size of 30 μm to 50 μm, a moisture content of <50%, a magnesium content of <1%, and a chlorine content of <0.05%.

[0030] Beneficial effects: According to one embodiment of the present invention, the nickel-cobalt precipitation method adopts a process flow of magnesium oxide activation treatment - active precipitant slurry alkali conversion treatment - nickel-cobalt precipitation. First, magnesium oxide is activated by alkaline solution, then mixed with free alkali solidification liquid for alkali conversion, and finally the alkali-converted mixed slurry is added to a solution containing nickel and cobalt to carry out nickel-cobalt precipitation reaction, thereby reducing the magnesium and chlorine content in the nickel-cobalt hydroxide product. The nickel-cobalt hydroxide product obtained by the alkaline solution activation of magnesium oxide for nickel-cobalt precipitation has large particles and low moisture content, which is more conducive to the subsequent processes.

[0031] Compared with the prior art, some embodiments of the present invention also have the following advantages:

[0032] 1) Pretreatment of magnesium oxide with an alkaline solution is used to digest magnesium oxide and convert it into magnesium hydroxide. When magnesium oxide is produced by a chloride system, the chlorine element carried by magnesium oxide can also be released into the solution during the digestion and activation process. In addition, the alkaline solution has an activating effect on the surface of magnesium hydroxide, which improves the reactivity of magnesium hydroxide and solves the problem of residual deactivated magnesium oxide in MHP products. At the same time, it also reduces the residual chlorine in the product.

[0033] 2) The activated precipitant slurry obtained from the activation treatment is mixed with a free alkali solidification solution containing magnesium and manganese. The free alkali in the slurry reacts with the magnesium and manganese ions in the solidification solution to generate active magnesium hydroxide and manganese hydroxide. These, along with the magnesium hydroxide produced from the digestion and activation of magnesium oxide, are added to a solution containing nickel and cobalt. During mixing, a nickel-cobalt precipitation reaction occurs, generating nickel-cobalt hydroxide. The purpose of this is to solidify the free hydroxide ions into a solid alkali, achieving alkali conversion, and slowing down the reaction rate of nickel-cobalt hydroxide formation during nickel-cobalt precipitation, thus resulting in larger, lower-moisture-content newly generated nickel-cobalt hydroxide particles.

[0034] 3) Post-processing of nickel-cobalt hydroxide can yield nickel-cobalt hydroxide products with lower impurity content.

[0035] 4) By returning a portion of the post-processed slurry as seed crystals to the nickel-cobalt immersion reaction, the growth of newly generated MHP can be promoted, which is more conducive to subsequent processes.

[0036] 5) The MHP product obtained by activating magnesium oxide with alkaline solution to precipitate nickel and cobalt in this application has a larger particle size, lower water content, lower magnesium content and lower chlorine content. Detailed Implementation

[0037] The technical solution of the present invention will be clearly and completely described below with reference to embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0038] As described above, the inventors of this application recognize that high-temperature treatment is unavoidable during the preparation of magnesium oxide, leading to the deactivation of some magnesium oxide, which remains in the product, resulting in a high magnesium content in the MHP product. Furthermore, the activated magnesium oxide product prepared using the magnesium chloride ammonia method has a high chlorine content; this chlorine residue in the product also results in a high chlorine content in the MHP, which is detrimental to subsequent refining processes. Based on these findings, this application is filed.

[0039] One embodiment of this application provides a method for activating magnesium oxide with an alkaline solution to precipitate nickel and cobalt, comprising magnesium oxide activation treatment, alkali conversion treatment of the active precipitant slurry, nickel and cobalt precipitation, and post-treatment. Specifically, it includes the following steps:

[0040] Step S1: Magnesium oxide is activated using an alkaline solution to obtain an activated precipitant slurry;

[0041] Step S2: Mix the activated precipitant slurry with the free alkali solidification liquid to obtain a mixed slurry;

[0042] Step S3: The mixed slurry is added to a solution containing nickel and cobalt to carry out a nickel and cobalt precipitation reaction, resulting in a nickel and cobalt precipitated slurry.

[0043] Step S4 involves post-processing the nickel-cobalt slurry after precipitation to obtain nickel-cobalt hydroxide (MHP) product.

[0044] The above-described embodiments, through magnesium oxide activation treatment, active precipitant slurry alkali conversion treatment, nickel-cobalt precipitation, and post-treatment, reduce the magnesium and chlorine content in the MHP product, resulting in a nickel-cobalt hydroxide product with large particles, low moisture content, and low impurity content. Furthermore, the MHP product obtained by activating magnesium oxide with the alkaline solution of this application for nickel-cobalt precipitation has a D50 particle size of 30–50 μm, a moisture content of <50%, a magnesium content of <1%, and a chlorine content of <0.05%.

[0045] Considering the inconsistent activity of commercially produced magnesium oxide, which can lead to precipitation, resulting in high or fluctuating magnesium content in the product, and consequently, uncontrollable quality decline, this application addresses this issue by using an alkaline solution to digest and activate magnesium oxide, thereby improving its reactivity. Furthermore, for some chlorine-containing magnesium oxides, this process also reduces residual chlorine in the product. Consequently, the magnesium oxide used in step S1 can be active magnesium oxide produced by various methods. For example, it can be magnesium oxide prepared by the hydrometallurgical process of laterite nickel ore, active magnesium oxide prepared by the magnesium chloride ammonia process, or active magnesium oxide produced by a salt lake chloride system. The effect is particularly significant when using highly active magnesium oxide produced by a chloride system, reducing both magnesium and chlorine content simultaneously.

[0046] In some preferred embodiments, to obtain better activation effects, the amount of alkali added to the alkaline solution is 0.1% to 99% of the mass of magnesium oxide, for example, 0.1%, 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 99%, etc. More preferably, the amount of alkali added is 5% to 50% of the mass of magnesium oxide to ensure uniform reaction, improve product yield, and avoid reagent waste. Furthermore, the alkali concentration of the alkaline solution is 0.1% to 40%, for example, 0.1%, 1%, 5%, 10%, 20%, 30%, 40%, etc. More preferably, the alkali concentration is 1% to 20%, which can achieve a high conversion rate while reducing the possibility of particle agglomeration. The alkaline solution can be one of sodium hydroxide, potassium hydroxide, calcium hydroxide, or ammonium hydroxide.

[0047] In some preferred embodiments, to ensure activation effect while improving activation efficiency, the activation treatment time is controlled to be 0.5 min to 8 h, such as 0.5 min, 10 min, 30 min, 60 min, 90 min, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, etc. More preferably, the activation treatment time is 5 min to 5 h to avoid the particles becoming too large and affecting the product activity due to the long time. The activation treatment temperature is controlled to be room temperature to 100°C, such as 25°C, 60°C, 80°C, 100°C, etc. When the temperature is too high, it will lead to a reduction in the active sites of magnesium hydroxide and a decrease in activity. More preferably, the activation treatment temperature is 40 to 80°C, and a temperature less than or equal to 80°C is more conducive to the formation of magnesium hydroxide with a large surface area and high activity.

[0048] The purpose of adding an alkaline solution in this application is to activate magnesium oxide under alkaline conditions, rather than simply to precipitate nickel and cobalt. Using the aforementioned alkaline solution, based on the optimized activation conditions (alkali concentration and dosage, activation temperature, and time), the magnesium oxide is digested and activated, which is more conducive to improving the activity of magnesium hydroxide, thereby increasing the efficiency of magnesium oxide nickel and cobalt precipitation. This solves the problem of magnesium residue in MHP products due to magnesium oxide deactivation in existing technologies and overcomes the limitations of magnesium oxide application. Furthermore, the alkaline solution digests magnesium oxide while releasing chlorine into the solution, effectively reducing the chlorine content in the MHP product.

[0049] In step S2 of this application, the free alkali curing solution contains magnesium and manganese elements for curing the free alkali. The conversion to alkali is completed by the reaction of magnesium and manganese ions with the free alkali. The free alkali curing solution can be selected from one or more of the slurry / solution produced in the nickel-cobalt precipitation process (such as slurry after nickel-cobalt precipitation, solution after nickel-cobalt precipitation, etc.) and other solutions containing magnesium and manganese metal ions. By mixing the activated precipitant slurry after activation treatment with the free alkali curing solution, the free hydroxide ions are solidified into solid alkali, realizing the conversion to alkali. The resulting mixed slurry has high precipitation activity. When added to a solution containing nickel-cobalt for nickel-cobalt precipitation, the precipitation efficiency of nickel-cobalt in the solution can be improved. Furthermore, by first solidifying the free hydroxide ions into solid alkali before precipitating nickel-cobalt, the reaction rate of nickel-cobalt hydroxide formation during the nickel-cobalt precipitation process is slowed down, resulting in larger and lower water content newly formed nickel-cobalt hydroxide particles.

[0050] In some preferred embodiments, to achieve better curing results, the total molar number of magnesium and manganese metal elements in the free alkali curing solution is not less than twice the molar number of hydroxide ions in the activating precipitant slurry. For example, the total molar number of magnesium and manganese in the free alkali curing solution is 2, 2.5, or 3 times the molar number of hydroxide ions in the activating precipitant slurry, etc. Further, the molar number of hydroxide ions in the activating precipitant slurry is 1.5 to 2.5 times the molar number of nickel and cobalt to be precipitated, for example, 1.5, 1.6, 2, or 2.5 times, etc., to improve the nickel and cobalt precipitation efficiency.

[0051] By optimizing the total molar amounts of magnesium and manganese metal elements in the free alkali curing solution, the molar amounts of hydroxide ions in the activating precipitant slurry, and the molar amounts of nickel and cobalt to be precipitated, the alkali conversion is ensured to proceed stably and orderly, allowing nickel and cobalt ions in the solution to fully precipitate and generate large-particle nickel and cobalt hydroxide. At the same time, the magnesium and manganese content in the nickel and cobalt hydroxide product can be further reduced.

[0052] In some preferred embodiments, the mixing time during the alkali conversion is 0.1 min to 1 h, for example, 0.1 min, 3 min, 10 min, 20 min, 30 min, 40 min, 50 min, 1 h, etc., preferably 1 min to 30 min; the mixing temperature is room temperature to 100°C, for example, 25°C, 60°C, 80°C, 100°C, etc., more preferably, the mixing temperature is 40°C to 70°C. By controlling the mixing temperature and time, the alkali conversion reaction can proceed more stably and efficiently under more suitable conditions, resulting in higher precipitation activity of the mixed slurry, which is more conducive to improving the efficiency and quality of subsequent nickel-cobalt precipitation.

[0053] Step S3 of this application involves adding the mixed slurry obtained after alkali conversion to a solution containing nickel and cobalt, so that the nickel and cobalt ions in the solution can be stably and fully precipitated, and the reaction rate of nickel-cobalt hydroxide generated during the nickel-cobalt precipitation process can be slowed down, thereby making the newly generated nickel-cobalt hydroxide particles larger and with lower water content, which is more conducive to subsequent liquid-solid separation and other processing steps.

[0054] In some preferred embodiments, the reaction time for nickel-cobalt precipitation is 0.5 h to 8 h, for example, 0.5 h, 1 h, 3 h, 5 h, 8 h, etc., preferably 1 h to 6 h; the reaction temperature is room temperature to 100 °C, for example, 25 °C, 60 °C, 80 °C, 100 °C, etc., preferably 40 °C to 80 °C. The above reaction time and temperature are more conducive to the precipitation of nickel-cobalt from the mixed slurry, and can further improve the precipitation efficiency and quality of nickel-cobalt in the solution. After the nickel-cobalt precipitation reaction, post-processing yields nickel-cobalt hydroxide product.

[0055] In some preferred embodiments, to obtain nickel-cobalt hydroxide products with lower impurity content, the slurry or filter cake is washed with an acid solution and / or a nickel-cobalt-containing solution as a washing agent during post-processing. The filter cake refers to the filter cake obtained after further pressure filtration and washing of the slurry. When using a nickel-cobalt-containing solution for slurry washing with stirring, the total nickel-cobalt content in the solution is 1–100 g / L, for example, 1 g / L, 4 g / L, 20 g / L, 40 g / L, 60 g / L, 80 g / L, 100 g / L, etc. When using an acid solution for acid washing, the acid solution can be one of sulfuric acid, hydrochloric acid, nitric acid, carbonic acid, oxalic acid, or citric acid. One or more of the above treatment methods can be selected in combination, in any order. For example, a three-combination treatment can be used: sequential carbonic acid treatment, nickel-cobalt-containing solution slurry stirring, and oxalic acid treatment.

[0056] Furthermore, in order to improve the washing efficiency, the washing time is controlled to be 0.5 to 8 hours each time, such as 0.5 hours, 1 hour, 3 hours, 5 hours, 8 hours, etc., preferably 1 to 5 hours; the temperature is from room temperature to 100°C, such as 25°C, 60°C, 80°C, 100°C, etc., preferably 40 to 80°C.

[0057] In addition, for the slurry after washing, a portion can be filtered and washed to obtain nickel cobalt hydroxide (MHP) product, while the other portion can be returned to the nickel cobalt precipitation reaction step as seed crystals to promote the growth of newly formed MHP, thereby generating large-particle nickel cobalt hydroxide.

[0058] In some alternative embodiments, after the nickel-cobalt precipitation reaction and before the washing process, the process further includes: thickening the nickel-cobalt precipitate slurry to obtain a separated slurry. Thickening significantly reduces the water content of the nickel-cobalt hydroxide product, improving product quality and economic efficiency. Since the volume of the thickened slurry is small, the washing process is easier when performing the above-mentioned washing treatment on this separated slurry (or the filter cake obtained after further pressure filtration and washing). Of course, when the volume of the nickel-cobalt precipitate slurry is small, thickening may be omitted, and the nickel-cobalt precipitate slurry (or the filter cake after pressure filtration and washing) can be washed directly.

[0059] The present application will now be described in detail with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection of the present application.

[0060] Example 1

[0061] The magnesium oxide used in this example is selected from highly active magnesium oxide produced by a salt lake chloride system.

[0062] Specifically, the following steps are included:

[0063] 1) Magnesium oxide was digested and activated using sodium hydroxide alkaline solution for 10 minutes at a temperature of 60°C to obtain an activated precipitant slurry. The concentration of the sodium hydroxide alkaline solution was 5%, and the amount of alkali added was 10% of the mass of magnesium oxide.

[0064] 2) Mix the activated precipitant slurry with the free alkali solidification solution (the solution after nickel-cobalt precipitation and the slurry after nickel-cobalt precipitation) for 3 minutes at a temperature of 60°C to obtain the mixed slurry. The molar amount of hydroxide ions in the activated precipitant slurry is 1.6 times the total molar amount of nickel and cobalt to be precipitated, and the total molar amount of magnesium and manganese metals in the liquid phase of the free alkali solidification solution is twice the molar amount of hydroxide ions in the activated precipitant slurry. "Nickel and cobalt to be precipitated" includes the nickel and cobalt in the "solution containing nickel and cobalt" from step 3), as well as the nickel and cobalt in the free alkali solidification solution. Their total molar amount can be determined through chemical analysis and calculated based on the process pipeline flow rate.

[0065] 3) The mixed slurry was added to a solution containing nickel and cobalt and reacted for 3 hours at a temperature of 60°C to obtain a nickel-cobalt precipitated slurry. The nickel-cobalt precipitate solution contained 3 g / L nickel and 0.3 g / L cobalt.

[0066] 4) After the reaction, the nickel-cobalt precipitate slurry is pressure filtered and washed to obtain nickel-cobalt hydroxide filter cake.

[0067] 5) The nickel-cobalt hydroxide filter cake was subjected to slurry stirring treatment with a nickel-cobalt containing solution for 3 hours at a reaction temperature of 60°C. The total nickel-cobalt content in the nickel-cobalt containing solution was 4 g / L.

[0068] 6) After washing with a nickel-cobalt solution, filter and continue treatment with carbonic acid for 3 hours at a reaction temperature of 60°C.

[0069] 7) After carbonic acid treatment, the product is filtered and washed. This filtered and washed product is the MHP product. The MHP product contains 45% nickel, <0.02% chlorine, 50% water, 40μm D50 particle size, and <0.8% magnesium.

[0070] Example 2

[0071] The magnesium oxide used in this example is the same as in Example 1.

[0072] Specifically, the following steps are included:

[0073] 1) Magnesium oxide was digested and activated using potassium hydroxide alkaline solution for 20 minutes at a temperature of 50°C to obtain an activated precipitant slurry. The concentration of the potassium hydroxide alkaline solution was 5%, and the amount of alkali added was 20% of the mass of magnesium oxide.

[0074] 2) Mix the activated precipitant slurry with the free alkali solidification solution (the slurry after nickel-cobalt precipitation) for 10 minutes at a temperature of 50°C to obtain the mixed slurry. The molar amount of hydroxide ions in the activated precipitant slurry is 2.0 times the total molar amount of nickel and cobalt to be precipitated, and the total molar amount of magnesium and manganese metals in the liquid phase of the free alkali solidification solution is 3 times the molar amount of hydroxide ions in the activated precipitant slurry. "Nickel-cobalt to be precipitated" includes the nickel and cobalt in the "solution containing nickel and cobalt" from step 3), as well as the nickel and cobalt in the free alkali solidification solution. Their total molar amount can be determined through chemical analysis and calculated based on the process pipeline flow rate.

[0075] 3) The mixed slurry was added to a solution containing nickel and cobalt and reacted for 3 hours at a temperature of 60°C to obtain a nickel-cobalt precipitated slurry. The nickel-cobalt precipitate solution contained 2.5 g / L nickel and 0.4 g / L cobalt.

[0076] 4) After the reaction, the nickel-cobalt precipitated slurry is thickened to obtain a thickened slurry. 5) The thickened slurry is then subjected to a slurry-stirring treatment using a nickel-cobalt-containing solution for 4 hours at a reaction temperature of 50°C. The total nickel-cobalt content in the nickel-cobalt-containing solution is 4 g / L.

[0077] 6) After washing with a nickel-cobalt solution, filter and continue treatment with oxalic acid for 4 hours at a reaction temperature of 50°C.

[0078] 7) After oxalic acid treatment, the product is filtered and washed. A portion of the filtered and washed product is used as the MHP product, and the other portion is returned as seed crystals to the nickel-cobalt immersion reaction step. The MHP product contains 43% nickel, <0.02% chlorine, 48% water, 42μm D50 particle size, and <0.7% magnesium.

[0079] Example 3

[0080] The magnesium oxide used in this example is the same as in Example 1.

[0081] Specifically, the following steps are included:

[0082] 1) Magnesium oxide was digested and activated using sodium hydroxide alkaline solution for 10 minutes at a temperature of 30°C to obtain an activated precipitant slurry. The concentration of the sodium hydroxide alkaline solution was 5%, and the amount of alkali added was 10% of the mass of magnesium oxide.

[0083] 2) Mix the activated precipitant slurry with the free alkali solidification solution (containing magnesium and manganese ions) for 0.5 min at a temperature of 30°C to obtain the mixed slurry. The molar amount of hydroxide ions in the activated precipitant slurry is 1.6 times the total molar amount of nickel and cobalt to be precipitated, and the total molar amount of magnesium and manganese metal in the liquid phase of the free alkali solidification solution is twice the molar amount of hydroxide ions in the activated precipitant slurry.

[0084] 3) The mixed slurry was added to a solution containing nickel and cobalt and reacted for 2 hours at a temperature of 30°C to obtain a nickel-cobalt precipitated slurry. The nickel-cobalt precipitated solution was the same as in Example 1, containing 3 g / L nickel and 0.3 g / L cobalt.

[0085] 4) After the reaction, the nickel-cobalt precipitate slurry is pressure filtered and washed to obtain nickel-cobalt hydroxide filter cake.

[0086] 5) The nickel-cobalt hydroxide filter cake was subjected to slurry stirring treatment with a nickel-cobalt containing solution for 3 hours at a reaction temperature of 30°C. The total nickel-cobalt content in the nickel-cobalt containing solution was 4 g / L.

[0087] 6) After slurry mixing, the product is filtered and washed. This filtered and washed product is the MHP product. The MHP product contains 40% nickel, <0.02% chlorine, 50% water, 32μm D50 particle size, and <0.8% magnesium.

[0088] Comparative Example 1

[0089] The magnesium oxide in this comparative example is the same as in Example 1.

[0090] Specifically, the following steps are included:

[0091] 1) Magnesium oxide was digested and activated using sodium hydroxide alkaline solution for 0.3 min at a temperature of 150°C to obtain an activated precipitant slurry. The concentration of the sodium hydroxide alkaline solution was 5%, and the amount of alkali added was 0.1% of the mass of magnesium oxide.

[0092] 2) Mix the activated precipitant slurry with the free alkali solidification solution (the solution after nickel-cobalt precipitation and the slurry after nickel-cobalt precipitation) for 0.1 min at a temperature of 20°C to obtain the mixed slurry. The molar amount of hydroxide ions in the activated precipitant slurry is one time the total molar amount of nickel and cobalt to be precipitated, and the total molar amount of magnesium and manganese metals in the liquid phase of the free alkali solidification solution is one time the molar amount of hydroxide ions in the activated precipitant slurry. "Nickel and cobalt to be precipitated" includes the nickel and cobalt in the "solution containing nickel and cobalt" from step 3), as well as the nickel and cobalt in the free alkali solidification solution. Their total molar amount can be determined through chemical analysis and calculated based on the process pipeline flow rate.

[0093] 3) The mixed slurry was added to a solution containing nickel and cobalt and reacted for 3 hours at a temperature of 60°C to obtain a nickel-cobalt precipitated slurry. The nickel-cobalt precipitated solution was the same as in Example 1, containing 3 g / L nickel and 0.3 g / L cobalt.

[0094] 4) After the reaction, the nickel-cobalt precipitate slurry is pressure filtered and washed to obtain nickel-cobalt hydroxide filter cake.

[0095] 5) The nickel-cobalt hydroxide filter cake was acid-treated with carbonic acid for 3 hours at a reaction temperature of 60°C.

[0096] 6) After carbonation treatment, the product is filtered and washed. This filtered and washed product is the MHP product. The MHP product contains 28% nickel, 0.07% chlorine, 55% water, 20μm D50 particle size, and 1.3% magnesium.

[0097] Comparative Example 2

[0098] Specifically, the following steps are included:

[0099] 1) Prepare a 25% sodium hydroxide aqueous solution.

[0100] 2) Add an aqueous sodium hydroxide solution to a solution containing nickel and cobalt and react for 3 hours at a temperature of 60°C to obtain a nickel-cobalt precipitate slurry. The nickel-cobalt precipitate slurry is the same as in Example 1, with nickel at 3 g / L and cobalt at 0.3 g / L. The molar amount of hydroxide ions in the aqueous sodium hydroxide solution is 2.0 times the total molar amount of nickel and cobalt to be precipitated.

[0101] 3) After the reaction, the nickel-cobalt precipitate slurry is thickened and separated. After thickening and separation, it is filtered and washed to obtain nickel-cobalt hydroxide filter cake. This filtered and washed nickel-cobalt hydroxide filter cake is used as the MHP product. The MHP product contains 35% nickel, has a water content of 70%, and a D50 particle size of 10 μm.

[0102] The description of this invention is given for illustrative and descriptive purposes only and is not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A method for activating magnesium oxide with an alkaline solution to precipitate nickel and cobalt, characterized in that, include: Activated magnesium oxide produced by a chloride system is activated using an alkaline solution for 0.5 min to 8 h at a temperature of 25 °C to 100 °C to obtain an activated precipitant slurry. The alkaline solution contains 0.1% to 99% alkali by mass of magnesium oxide and has a concentration of 0.1% to 40%. The alkaline solution is at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide, and ammonium hydroxide solutions. The activated precipitant slurry is mixed with a free alkali curing liquid to obtain a mixed slurry; wherein the free alkali curing liquid contains magnesium and manganese elements for curing free alkali; The mixed slurry is added to a solution containing nickel and cobalt to carry out a nickel and cobalt precipitation reaction, resulting in a nickel and cobalt precipitated slurry. The nickel-cobalt slurry after precipitation is post-processed to obtain nickel-cobalt hydroxide product.

2. The method for activating magnesium oxide with alkaline solution to precipitate nickel and cobalt according to claim 1, characterized in that, The free alkali curing solution is one or more of the following: slurry after nickel-cobalt precipitation, solution after nickel-cobalt precipitation, and other solutions containing magnesium and manganese ions. The total molar amount of magnesium and manganese in the free alkali curing liquid is not less than twice the molar amount of hydroxide in the activated precipitant slurry. The molar amount of hydroxide ions in the activated precipitant slurry is 1.5 to 2.5 times the total molar amount of nickel and cobalt to be precipitated.

3. The method for activating magnesium oxide with alkaline solution to precipitate nickel and cobalt according to claim 1, characterized in that, The mixing time is 0.1 min to 1 h, and the mixing temperature is 25℃ to 100℃.

4. The method for activating magnesium oxide with alkaline solution to precipitate nickel and cobalt according to claim 1, characterized in that, When performing the nickel-cobalt immersion reaction, the reaction time is 0.5h to 8h and the reaction temperature is 25℃ to 100℃.

5. The method for activating magnesium oxide with alkaline solution to precipitate nickel and cobalt according to claim 1, characterized in that, Post-processing includes: The slurry or the filter cake obtained after pressure filtration and washing is washed; wherein, one or more of methods selected from method one and method two are used for washing treatment, method one is to use a nickel-cobalt containing solution for slurry stirring treatment, and method two is to use an acid solution for acid treatment; The washed slurry is filtered to obtain the MHP product; and / or the washed slurry is returned as seed crystals to the nickel-cobalt immersion reaction step.

6. The method for activating magnesium oxide with alkaline solution to precipitate nickel and cobalt according to claim 5, characterized in that, During the washing process, the treatment time is 0.5h to 8h, and the temperature is 25℃ to 100℃. The total nickel-cobalt content in the nickel-cobalt-containing solution is 1 g / L to 100 g / L; The acid solution is one or more of sulfuric acid, hydrochloric acid, nitric acid, carbonic acid, oxalic acid, and citric acid.

7. The method for activating magnesium oxide with alkaline solution to precipitate nickel and cobalt according to claim 5, characterized in that, Before the washing process, the process also includes thickening the nickel-cobalt slurry after precipitation to obtain a thickened slurry.

8. A nickel-cobalt hydroxide product, characterized in that, The magnesium oxide was prepared by alkaline solution activation and nickel-cobalt precipitation method according to any one of claims 1-7, and its D50 particle size is 30μm to 50μm, water content is <50%, magnesium content is <1%, and chlorine content is <0.05%.