Method for preparing battery-grade nickel-cobalt-manganese sulfate crystal from low-grade nickel matte

Abstract

A method for preparing a battery-grade nickel-cobalt-manganese sulfate crystal from low-grade nickel matte, comprising the following steps: S1, sequentially carrying out high-pressure leaching, iron and aluminum removal, and nickel-cobalt-manganese precipitation treatment on laterite-nickel ore to obtain underflow containing nickel-cobalt-manganese hydroxide, wherein the pH value of the underflow is 7-8; S2, after the low-grade nickel matte is subjected to oxygen pressure leaching by using sulfuric acid and oxygen, obtaining a leach slurry containing residual acid, adding the underflow into the leach slurry to obtain a mixed slurry, and using the underflow to adjust the pH value of the mixed slurry to be 3-5; and S3, carrying out filter pressing on the mixed slurry to obtain a filtrate and tailings, and carrying out nickel-cobalt-manganese co-extraction, concentration and crystallization on the filtrate to obtain a nickel-cobalt-manganese sulfate crystal. The nickel-cobalt-manganese utilization rate is high, impurities are few, reagent consumption and technological processes are reduced, and the transportation efficiency is high.

Description

A method for preparing battery-grade nickel cobalt manganese sulfate crystals from low-grade nickel matte Technical Field

[0001] The present invention relates to the technical field of hydrometallurgy, and in particular to a method for preparing battery-grade nickel cobalt manganese sulfate crystals from low-grade nickel matte. Background Art

[0002] Nickel, cobalt and manganese are important new energy materials, and laterite nickel ore is one of the main sources of nickel, cobalt and manganese metals. Among them, the pyrometallurgical smelting process is used due to its advantages such as simple operation and short process flow. The process is to prepare high-grade nickel matte through reduction roasting, high-temperature impurity removal and other steps. For example, the process of laterite nickel ore-electric furnace smelting (sulfurization)-low-grade nickel matte-converter blowing-high-grade nickel matte is widely adopted by various smelters. Specifically: the laterite nickel ore is dried and pre-reduced in a rotary kiln, and then smelted in an electric furnace. At the same time, a sulfiding agent is added to obtain low-grade nickel matte (Ni content of about 20%, iron content of about 65%), and then high-grade nickel matte (Ni content of about 60%, iron content of about 5%) is prepared through PS converter blowing. The obtained high-grade nickel matte is used as a crude product as a raw material in different fields such as stainless steel and battery materials. However, the focus of the pyrometallurgical process for high-grade laterite nickel ore is only on nickel. In the process of blowing from low-grade nickel matte to high-grade nickel matte, although the nickel content in the product increases, the cobalt and manganese associated with the laterite nickel ore are not taken into consideration, resulting in a large amount of resource waste. The huge energy consumption makes the cost of producing high-grade nickel matte by pyrometallurgy significantly higher than that of the wet process. Low-grade nickel matte is the primary product in the pyrometallurgical process. As a nickel-iron alloy, it also contains metals such as cobalt and manganese. Using low-grade nickel matte as a raw material to prepare a high-purity nickel-cobalt-manganese sulfate solution can significantly shorten the process flow and improve the utilization rate of nickel, cobalt and manganese metals. In the related art, after using low-grade nickel matte as a raw material to directly and selectively leach nickel, cobalt and manganese, the impurity iron content in the leachate is very high. Therefore, the pH of the solution after leaching needs to be adjusted with lime milk to preliminarily remove impurity ions, and then a single nickel sulfate, cobalt sulfate and manganese sulfate crystals are prepared through an extraction process. The process flow is complicated and the acid consumption is high; the utilization rate of nickel, cobalt and manganese is low.

[0003] In addition, low-grade laterite nickel ore can be used to produce nickel, cobalt and manganese hydroxide after high-pressure wet smelting and precipitation and impurity removal. Nickel, cobalt and manganese hydroxide is an intermediate product that can be further purified by wet smelting plants, making it another important means of obtaining nickel, cobalt and manganese. However, the filter cake of nickel, cobalt and manganese hydroxide contains about 50-55% water, which is costly to transport during transportation. Moreover, more than half of the water is water, which increases costs. During the purification process, acid needs to be added to dissolve the nickel, cobalt and manganese hydroxide again. After extraction, single nickel sulfate, cobalt sulfate and manganese sulfate solutions are prepared respectively. The additional sulfuric acid also increases reagent consumption, resulting in high losses of nickel, cobalt and manganese, and the process is complicated.

[0004] Therefore, it is necessary to provide a technical solution that can simultaneously solve the problems of low nickel, cobalt and manganese utilization, high reagent consumption, complex process and inconvenient transportation in the process of extracting nickel, cobalt and manganese from low-grade nickel matte and low-grade laterite nickel ore.

[0005] Summary of the Invention

[0006] In view of this, the present application provides a method for preparing battery-grade nickel cobalt manganese sulfate crystals from low-grade nickel matte, which has high nickel, cobalt and manganese utilization rate, few impurities, reduced reagent consumption and process flow, and high transportation efficiency.

[0007] In order to achieve the above technical objectives, this application adopts the following technical solutions:

[0008] The present application provides a method for preparing battery-grade nickel cobalt manganese sulfate crystals from low-grade nickel matte, comprising the following steps:

[0009] S1. The laterite nickel ore was sequentially subjected to high-pressure leaching, iron and aluminum removal, nickel, cobalt and manganese precipitation treatment to obtain an underflow containing nickel, cobalt and manganese hydroxides, the underflow having a pH value of 7-8;

[0010] S2. After the low nickel matte is oxygen-pressure leached using sulfuric acid and oxygen, a leaching slurry containing residual acid is obtained, the underflow is added to the leaching slurry to obtain a mixed slurry, and the pH value of the mixed slurry is adjusted to 3-5 using the underflow;

[0011] S3. The mixed slurry is filtered to obtain a filtrate and tailings, and the filtrate is subjected to nickel-cobalt-manganese co-extraction and concentrated crystallization to obtain nickel-cobalt-manganese sulfate crystals.

[0012] Preferably, in step S1, the process conditions for removing iron and aluminum are: controlling the temperature to 80-85° C. and the pH to 2-5.

[0013] Preferably, in step S1, the process conditions for precipitating nickel, cobalt and manganese are: controlling the temperature to be 70-80° C. and the pH to be 7-8.

[0014] Preferably, in step S1, the process conditions for high-pressure leaching are: a temperature of 250-260° C., a pressure of 4.5-5 MPa, and a high-pressure leaching time of 1 hour. Preferably, in step S2, the temperature for oxygen pressure leaching is 180-220° C., the pressure for oxygen pressure leaching is 2.5-3.3 MPa, the oxygen partial pressure for oxygen pressure leaching is 20-30%, and the oxygen pressure leaching time is 2-10 hours.

[0015] Preferably, in step S3, the extractant used for nickel-cobalt-manganese co-extraction is DY319 extractant.

[0016] Preferably, the particle size of the low nickel matte is 74-150 μm.

[0017] Preferably, in step S2, the acid-ore ratio of sulfuric acid to low-grade nickel matte is 0.025-0.625:1.

[0018] Preferably, in step S2, the pH value of the mixed slurry is adjusted to 5 using the underflow.

[0019] In a second aspect, the present application provides a battery-grade nickel cobalt manganese sulfate crystal.

[0020] The beneficial effects of this application are as follows:

[0021] This application solves the problem of too much iron in low-grade nickel matte, so that most of the iron is converted into ferric oxide and sulfuric acid through the hydrolysis reaction of oxygen pressure leaching, and the other part of the iron is converted into Fe in the leaching slurry. 3+ The bottom flow after high-pressure leaching of laterite nickel ore is adjusted to pH 3-5 to form ferric hydroxide. The ferric oxide and ferric hydroxide enter the slag phase to remove the iron impurities in the low-grade nickel matte.

[0022] The present application combines the low-grade nickel matte oxygen pressure leaching and laterite nickel ore high-pressure leaching processes, and combines the low-grade nickel matte oxygen pressure leaching slurry with the bottom flow of nickel, cobalt and manganese precipitated after high-pressure leaching of laterite nickel ore. This is not only beneficial for removing impurity iron in the low-grade nickel matte, but also can consume the residual acid in the low-grade nickel matte oxygen pressure leaching slurry during the iron removal process, and at the same time, the nickel, cobalt and manganese hydroxides in the bottom flow of the precipitated nickel, cobalt and manganese are dissolved again into nickel ions, manganese ions and cobalt ions and enter the liquid phase and merged with the liquid phase containing nickel, cobalt and manganese in the low-grade nickel matte, and then directly recover Ni, Co and Mn in the liquid phase through co-extraction; the utilization rate of nickel, cobalt and manganese in this scheme is high, which can reduce reagent consumption, minimize the use of filter presses, improve transportation efficiency, and shorten the process steps of subsequent treatment of nickel, cobalt and manganese hydroxides. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 is a process flow chart of the present application. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] The present application provides a method for preparing battery-grade nickel cobalt manganese sulfate crystals from low-grade nickel matte, comprising the following steps:

[0026] S1. The laterite nickel ore was sequentially subjected to high-pressure leaching, iron and aluminum removal, nickel, cobalt and manganese precipitation treatment to obtain an underflow containing nickel, cobalt and manganese hydroxides, the underflow having a pH value of 7-8;

[0027] S2. After the low nickel matte is oxygen-pressure leached using sulfuric acid and oxygen, a leaching slurry containing residual acid is obtained, the underflow is added to the leaching slurry to obtain a mixed slurry, and the pH value of the mixed slurry is adjusted to 2-5 using the underflow;

[0028] S3. The mixed slurry is filtered to obtain a filtrate and tailings, and the filtrate is subjected to nickel-cobalt-manganese co-extraction and concentrated crystallization to obtain nickel-cobalt-manganese sulfate crystals.

[0029] The specific process is shown in Figure 1. This scheme is formed by combining two processes; in step S1, laterite nickel ore is used as raw material, and high-pressure leaching is performed to obtain a first leachate, which contains Fe, Al, Mn, Ni, Co and other impurities, and then the first leachate is subjected to an iron-aluminum removal operation to obtain aluminum-iron slag and a second leachate, and iron and aluminum are precipitated and removed in the form of iron-aluminum slag. The second leachate contains Mn, Ni, Co and impurities, and then the second leachate is subjected to nickel-cobalt-manganese precipitation treatment to obtain a supernatant and an underflow precipitate. The underflow precipitate is a slurry containing nickel, cobalt and manganese hydroxide, and the pH of the underflow is 7-8; in step S2, low-matte nickel is used as raw material, and oxygen pressure leaching is performed under the action of oxygen and sulfuric acid to obtain a leaching slurry. The leaching slurry contains residual acid, a slurry slag phase, and a slurry liquid phase. The slurry slag phase includes ferric oxide obtained by oxygen pressure leaching hydrolysis, and the slurry liquid phase contains unhydrolyzed iron ions. The residual acid comes from oxygen pressure leaching. The sulfuric acid added before and the sulfuric acid produced by oxygen pressure leaching hydrolysis are extracted, and the bottom flow obtained in step S1 is mixed with the leaching slurry. The different pH values ​​of the bottom flow and the leaching slurry are used to adjust the mixing ratio of the bottom flow and the leaching slurry. The obtained mixture is a mixed slurry, and the pH value of the mixed slurry is 3-5; the mixed slurry is a mixture of solid phase and liquid phase after the reaction of the bottom flow and the leaching slurry, the solid phase components are mainly ferric oxide slag and ferric hydroxide slag, and the main components of the liquid phase are salt solutions of nickel, cobalt and manganese. The nickel, cobalt and manganese in the liquid phase come from low-matte nickel and laterite nickel ore. After step S2, nickel, cobalt and manganese hydroxide are converted into dissolved nickel, cobalt and manganese. Therefore, the content of nickel, cobalt and manganese in the liquid phase increases, which is beneficial to subsequent extraction and improves the extraction efficiency; in step S3, the solid phase and liquid phase in the mixed slurry are separated by filter press to obtain tailings and filtrate respectively, and the filtrate is subjected to nickel, cobalt and manganese co-extraction and concentrated crystallization to obtain nickel, cobalt and manganese sulfate crystals.

[0030] In the present application, the extraction of nickel, cobalt and manganese from low-grade nickel matte is combined with the process of treating the underflow of laterite nickel ore, which can solve the following problems at the same time: 1. The impurity iron content in low-grade nickel matte is too high, and the iron removal steps are complicated, which affects the purity of the finished nickel, cobalt and manganese products; 2. The utilization rates of nickel, cobalt and manganese in laterite nickel ore and low-grade nickel matte are low; 3. When the two processes are carried out separately, the consumption of reagents such as lime and sulfuric acid is too large; 4. The filter press is used too many times and the process is complicated; 5. There is too much water in the underflow products of nickel, cobalt and manganese hydroxide, and the transportation cost is high.

[0031] The principle is as follows: by combining the low nickel matte leaching and laterite nickel ore high pressure leaching process, the leaching slurry containing residual acid after low nickel matte oxygen pressure is combined with the bottom flow of nickel, cobalt and manganese precipitated after high pressure leaching of laterite nickel ore. The residual acid in the low nickel matte leaching slurry is consumed by the difference in acidity and alkalinity between the two, and the amount of bottom flow is adjusted to make the pH reach the precipitation of Fe 3+ The conditions are to form iron hydroxide to remove the impurities Fe dissolved in the leaching slurry. 3+ At the same time, the bottom flow of nickel, cobalt and manganese precipitated from laterite nickel ore (containing nickel, cobalt and manganese hydroxide, with a pH of 7-8) changes in pH after being mixed with the leaching slurry, and the nickel, cobalt and manganese hydroxides are dissolved again into the liquid phase of the mixed slurry to form nickel, cobalt and manganese ions for subsequent treatment, which overcomes the problem of excessive water in the bottom flow product of nickel, cobalt and manganese hydroxide that requires pressure filtration and transportation, and improves the efficiency of subsequent extraction of nickel, cobalt and manganese; the bottom flow is mixed with the leaching slurry to obtain a mixed slurry, the mixed slurry is pressure filtered to obtain a filtrate, and the nickel, cobalt and manganese in the filtrate can be directly recovered by co-extraction, while improving the utilization rate of nickel, cobalt and manganese in low-grade nickel matte and laterite nickel ore, reducing reagent consumption and improving transportation efficiency.

[0032] This application can minimize the use of filter presses. In the prior art, the subsequent steps of processing nickel cobalt manganese hydroxide require a filter press, and after the low-grade nickel oxide oxygen pressure leaching, the pH is adjusted and the impurities are removed, and they all need to be filtered to achieve the effect of solid-liquid separation; this application combines the two processes, and only needs to be filtered once after the pH value is adjusted, and nickel cobalt manganese is co-extracted in the filtrate, and then nickel cobalt manganese sulfate crystals can be directly prepared by crystallization, and then transported in this way. This not only avoids the problem of excessive water in the bottom flow product of nickel cobalt manganese hydroxide contained in laterite nickel ore, but also can directly trade nickel cobalt manganese sulfate as raw material, thereby improving the economic benefits of the enterprise.

[0033] In step S1, the process conditions for removing iron and aluminum are: controlling the temperature to 80-85°C and the pH to 2-5; the leachate is subjected to the above process to remove iron and aluminum, and after separation, iron-aluminum slag and a second leachate are obtained, and the second leachate contains Mn, Ni, Co and a small amount of unprecipitated iron ions and aluminum ions.

[0034] In step S1, the process conditions for precipitating nickel, cobalt and manganese are: controlling the temperature to 70-80°C and the pH to 7-8; the second leachate obtained after removing iron and aluminum is subjected to nickel, cobalt and manganese precipitation according to the above process to obtain an underflow precipitate containing nickel, cobalt and manganese hydroxides. At this time, the pH of the underflow is 7-8.

[0035] In step S1, the process conditions of high-pressure leaching are: 250-260° C., 4.5-5 MPa, and reaction for 1 hour; the equipment used is an autoclave, and a first leachate is obtained by high-pressure leaching and separation, and the first leachate contains Fe, Al, Mn, Ni, Co and other impurities.

[0036] In step S2, the temperature of the oxygen pressure leaching is 180-220°C, the pressure of the oxygen pressure leaching is 2.5-3.3 MPa, the oxygen partial pressure of the oxygen pressure leaching is 20-30%, and the oxygen pressure leaching time is 2-10 hours. Through oxygen pressure leaching, most of the iron in the low-grade nickel matte can be hydrolyzed to form ferric oxide in the leaching slurry, but a large amount of unhydrolyzed iron impurities still exist in the leaching slurry.

[0037] In step S3, the extractant used for nickel-cobalt-manganese co-extraction is DY319 extractant.

[0038] In step S2, the acid-ore ratio of sulfuric acid to low-grade nickel matte is 0.025-0.625:1; under this condition, it is ensured that Fe can undergo hydrolysis reaction to oxidize iron to the maximum extent.

[0039] The particle size of low nickel matte is 74-150μm.

[0040] In step S2, the pH value of the mixed slurry is adjusted to 5 by using the underflow. At this pH value, it is most favorable for Fe ions to form ferric hydroxide.

[0041] The present application provides a battery-grade nickel-cobalt-manganese sulfate crystal with high purity and low impurity iron content.

[0042] The present invention is further described below through specific examples.

[0043] Example 1

[0044] A method for preparing battery-grade nickel cobalt manganese sulfate crystals from low-grade nickel matte comprises the following steps:

[0045] S1. 100kg of laterite nickel ore was placed in an autoclave and reacted at 250°C and a pressure of 4.5Mpa for 1h. High-pressure leaching was performed. After standing, a first leachate was obtained. The pH of the first leachate was adjusted to 2, and the temperature was controlled to 80°C for iron and aluminum removal. After standing, iron-aluminum slag and a second leachate were obtained. The pH of the second leachate was adjusted to 8, and the temperature was controlled to 70°C for nickel, cobalt and manganese precipitation. After standing, a supernatant and an underflow precipitate were obtained. The underflow precipitate contained nickel, cobalt and manganese hydroxides and had a pH of 8.

[0046] S2. Ball-mill 100 kg of low-grade nickel matte to obtain low-grade nickel matte with a particle size of 150 μm, put sulfuric acid and the ball-milled low-grade nickel matte into an autoclave at an acid-ore ratio of 0.625:1, continue to add sulfuric acid and introduce oxygen, perform high-temperature oxygen pressure leaching, and perform hydrolysis reaction, wherein the temperature of oxygen pressure leaching is 220°C, the pressure of oxygen pressure leaching is 3.3 MPa, the oxygen partial pressure of oxygen pressure leaching is 30%, and the time of oxygen pressure leaching is 10 h. After the oxygen pressure leaching is completed, a leaching slurry containing residual acid is obtained, and the underflow is added to the leaching slurry to obtain a mixed slurry, and the amount of the underflow is adjusted until the pH value of the mixed slurry is 5;

[0047] S3. The mixed slurry is filter-filtered to obtain a filtrate and tailings, and DY319 extractant is added to the filtrate for nickel-cobalt-manganese co-extraction to obtain a nickel-cobalt-manganese sulfate solution. The nickel-cobalt-manganese sulfate solution is concentrated and crystallized to obtain nickel-cobalt-manganese sulfate crystals.

[0048] Example 2

[0049] A method for preparing battery-grade nickel cobalt manganese sulfate crystals from low-grade nickel matte, wherein the other steps are the same as those in Example 1, except that the temperature of the oxygen pressure leaching is 220°C, the pressure of the oxygen pressure leaching is 2.8 MPa, the oxygen partial pressure of the oxygen pressure leaching is 20%, and the time of the oxygen pressure leaching is 10 hours.

[0050] Example 3

[0051] A method for preparing battery-grade nickel cobalt manganese sulfate crystals from low-grade nickel matte, the other contents of which are the same as those in Example 1, except that in step S2, the pH value of the mixed slurry is 4.

[0052] Example 4

[0053] A method for preparing battery-grade nickel cobalt manganese sulfate crystals from low-grade nickel matte comprises the following steps:

[0054] S1. 100kg of laterite nickel ore was placed in an autoclave and subjected to high-pressure leaching at 260°C and a pressure of 5 MPa for 1h. After standing, a first leachate was obtained, and the pH of the first leachate was adjusted to 5. The temperature was controlled to 85°C for removing iron and aluminum. After standing, iron-aluminum slag and a second leachate were obtained. The pH of the second leachate was adjusted to 7. The temperature was controlled to 80°C for precipitation of nickel, cobalt and manganese. After standing, a supernatant and an underflow precipitate were obtained. The underflow precipitate contained nickel, cobalt and manganese hydroxides and had a pH of 7.

[0055] S2. Ball-mill 100 kg of low-grade nickel matte to obtain low-grade nickel matte with a particle size of 74 μm, put sulfuric acid and the ball-milled low-grade nickel matte into an autoclave at an acid-ore ratio of 0.025:1, continue to add sulfuric acid and introduce oxygen, perform high-temperature oxygen pressure leaching, and perform hydrolysis reaction, wherein the temperature of oxygen pressure leaching is 180°C, the pressure of oxygen pressure leaching is 2.5 MPa, the oxygen partial pressure of oxygen pressure leaching is 25%, and the time of oxygen pressure leaching is 2 h. After the oxygen pressure leaching is completed, a leaching slurry containing residual acid is obtained, the underflow is added to the leaching slurry to obtain a mixed slurry, and the amount of underflow is adjusted until the pH value of the mixed slurry is 3;

[0056] S3. The mixed slurry is filter-filtered to obtain a filtrate and tailings, and DY319 extractant is added to the filtrate for nickel-cobalt-manganese co-extraction to obtain a nickel-cobalt-manganese sulfate solution. The nickel-cobalt-manganese sulfate solution is concentrated and crystallized to obtain nickel-cobalt-manganese sulfate crystals.

[0057] Comparative Example 1

[0058] A method for preparing battery-grade nickel cobalt manganese sulfate crystals from low-grade nickel matte comprises the following steps:

[0059] K1. Ball-milling 100 kg of low-grade nickel matte to obtain low-grade nickel matte with a particle size of 150 μm, placing sulfuric acid and the ball-milled low-grade nickel matte into an autoclave at an acid-ore ratio of 0.625:1, continuously adding sulfuric acid and introducing oxygen to perform high-temperature oxygen pressure leaching, and performing a hydrolysis reaction, wherein the oxygen pressure leaching temperature is 220° C., the oxygen pressure leaching pressure is 3.3 MPa, the oxygen partial pressure is 30%, and the oxygen pressure leaching time is 10 h. After the oxygen pressure leaching is completed, a leaching slurry containing residual acid is obtained, and lime milk is added to adjust the pH to 4 to obtain a mixture;

[0060] K2. The mixture is filter-filtered to obtain a filtrate and tailings, and DY319 extractant is added to the filtrate for nickel-cobalt-manganese co-extraction to obtain a nickel-cobalt-manganese sulfate solution. The nickel-cobalt-manganese sulfate solution is concentrated and crystallized to obtain nickel-cobalt-manganese sulfate crystals.

[0061] Evaluation Test

[0062] The purity and iron impurity content of the nickel cobalt manganese sulfate crystals in Examples 1-3 and Comparative Example 1, as well as the recovery rate of nickel cobalt manganese, were tested; the test results are shown in Table 1.

[0063] Table 1 Product purity and utilization test results

[0064] In Table 1, when comparing Example 1 with Example 2, the reduction of oxygen partial pressure and oxygen dosage leads to a decrease in the total recovery rate of nickel, cobalt and manganese, which is mainly due to the reduction of oxygen content, which limits the conversion of Fe in nickel matte to Fe. 3+The conversion efficiency is low, and it cannot be hydrolyzed to produce sulfuric acid, thus affecting the leaching rate of Ni, Co, and Mn.

[0065] Comparing Example 1 with Example 3, the pH values ​​of the mixed slurry in step S2 are different, resulting in different degrees of iron ion precipitation, indicating that the iron impurity removal effect of Example 1 is better than that of Example 3.

[0066] Comparative Example 1 is compared with Example 3. The process of extracting nickel cobalt manganese sulfate from low nickel matte is carried out alone. The process conditions are the same, but it is not combined with the treatment process of the bottom flow from laterite nickel ore. Although higher purity nickel cobalt manganese sulfate crystals can also be prepared, the purity and recovery rate are slightly lower than those in Example 3. However, the whole process requires a large amount of lime milk for impurity removal, and the reagent cost is high.

[0067] In Examples 1-4, the purity of the obtained nickel cobalt manganese sulfate crystals is greater than 99%, and the recovery rate is greater than 90%, indicating that this solution has a good recovery rate for nickel cobalt manganese, with few impurities and high purity. From the perspective of the process flow, no additional reagents are used, which is conducive to reducing costs.

[0068] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing battery-grade nickel cobalt manganese sulfate crystals from low-grade nickel matte, characterized in that: The following steps are involved: S1. The laterite nickel ore is sequentially subjected to high-pressure leaching, iron and aluminum removal, and nickel, cobalt and manganese precipitation to obtain an underflow containing nickel, cobalt and manganese hydroxides, wherein the pH value of the underflow is 7-8; S2. After oxygen pressure leaching the low-grade nickel matte with sulfuric acid and oxygen, a leaching slurry containing residual acid is obtained, the underflow is added to the leaching slurry to obtain a mixed slurry, and the pH value of the mixed slurry is adjusted to 3-5 using the underflow; S3. The mixed slurry is filtered to obtain a filtrate and tailings, and the filtrate is subjected to nickel-cobalt-manganese co-extraction, concentration and crystallization to obtain nickel-cobalt-manganese sulfate crystals.

2. The method for preparing battery-grade nickel cobalt manganese sulfate crystals from low nickel matte according to claim 1, characterized in that: In step S1, the process conditions for removing iron and aluminum are: controlling the temperature to 80-85°C and the pH to 2-5.

3. The method for preparing battery-grade nickel cobalt manganese sulfate crystals from low nickel matte according to claim 1, characterized in that: In step S1, the process conditions for precipitating nickel, cobalt and manganese are: controlling the temperature to 70-80°C and the pH to 7-8.

4. The method for preparing battery-grade nickel cobalt manganese sulfate crystals from low nickel matte according to claim 1, characterized in that: In step S1, the process conditions of high-pressure leaching are: controlling the temperature to 250-260° C., the pressure to 4.5-5 MPa, and the high-pressure leaching time to 1 hour.

5. The method for preparing battery-grade nickel cobalt manganese sulfate crystals from low nickel matte according to claim 1, characterized in that: In step S2, the temperature of oxygen pressure leaching is 180-220°C, the pressure of oxygen pressure leaching is 2.5-3.3 MPa, the oxygen partial pressure of oxygen pressure leaching is 20-30%, and the time of oxygen pressure leaching is 2-10 hours.

6. The method for preparing battery-grade nickel cobalt manganese sulfate crystals from low nickel matte according to claim 1, characterized in that: In step S3, the extractant used for the nickel-cobalt-manganese co-extraction is DY319 extractant.

7. The method for preparing battery-grade nickel cobalt manganese sulfate crystals from low nickel matte according to claim 1, characterized in that: The particle size of the low nickel matte is 74-150 μm.

8. The method for preparing battery-grade nickel cobalt manganese sulfate crystals from low-grade nickel matte according to claim 1, characterized in that, in step S2, the acid-ore ratio of sulfuric acid to low-grade nickel matte is 0.025-0.625:

1.

9. The method for preparing battery-grade nickel cobalt manganese sulfate crystals from low nickel matte according to claim 1, characterized in that: In step S2, the pH value of the mixed slurry is adjusted to 5 using the underflow.

10. Battery-grade nickel-cobalt-manganese sulfate crystals obtained by the method according to any one of claims 1 to 9.

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