Method for extracting nickel-cobalt-manganese and chromium from laterite nickel ore

Abstract

A method for extracting nickel-cobalt-manganese and chromium from laterite nickel ore. The method comprises the following steps: subjecting laterite nickel ore to high-pressure acid leaching, so as to obtain a leachate; neutralizing the leachate, and subjecting same to solid-liquid separation, so as to obtain iron-aluminum slag and a solution from which iron and aluminum have been removed; adsorbing the solution, from which iron and aluminum have been removed, by using a resin, which has selectivity for hexavalent chromium, so as to obtain a chromium-removed solution and an adsorbed resin, wherein the adsorbed resin comprises chromium ions, and desorbing ions from the adsorbed resin by using a desorption solution, so as to obtain an enriched solution comprising chromium ions; and extracting the chromium-removed solution, so as to obtain an extracted solution and a nickel-cobalt-manganese raffinate, wherein the extracted solution comprises impurity metal ions.

Description

A method for extracting nickel, cobalt, manganese and chromium from laterite nickel ore Technical Field

[0001] The invention belongs to the technical field of laterite nickel ore processing, and in particular relates to a method for extracting nickel, cobalt, manganese and chromium from laterite nickel ore. Background Art

[0002] The production of nickel cobalt hydroxide from laterite nickel ore typically involves high-pressure acid leaching, which produces impurity metals such as hexavalent chromium. The presence of hexavalent chromium can affect the performance of the nickel cobalt hydroxide. Furthermore, hexavalent chromium is also present in the wastewater and residue produced by the high-pressure acid leaching process, potentially causing heavy metal pollution in the environment.

[0003] The existing method of removing chromium is usually to add a reducing agent in the high-pressure leaching stage to inhibit the chromium 6+ For example, patent CN113481365A provides a method for reducing hexavalent chromium in a high-pressure acid leaching process of laterite nickel ore. In the preparation stage of high-pressure acid leaching and / or during the high-pressure acid leaching process, a reducing agent is added to the system to reduce the hexavalent chromium during the high-pressure acid leaching process. Patent CN111498916A discloses a method for removing hexavalent chromium in the process of preparing nickel cobalt hydroxide from laterite nickel ore. In this method: before the high-pressure acid leaching step, the laterite nickel ore slurry is preheated, and before the preheating step, a first reducing agent is added to the laterite nickel ore slurry, and then the laterite nickel ore slurry to which the first reducing agent is added enters the high-pressure acid leaching step; or, a second reducing agent is added to the leachate obtained in the circulating leaching step, and then the residual ore neutralization step is entered.

[0004] The aforementioned technologies all involve adding reducing agents during the high-pressure leaching stage, which inhibits the hydrolytic removal of Fe during the leaching process. Therefore, there is a need for a method for co-processing laterite nickel ore without the addition of reducing agents, and for directly preparing a nickel-cobalt-manganese ternary precursor.

[0005] Summary of the Invention

[0006] To address the challenges currently faced in laterite nickel ore hydrometallurgy, the present invention aims to provide a method for extracting nickel, cobalt, manganese, and chromium from laterite nickel ore. This method, without the need for adding a reducing agent, allows for the direct separation and extraction of metallic chromium, nickel, cobalt, and manganese from a complex leachate.

[0007] To achieve the above object, the present invention is implemented through the following technical solutions:

[0008] A method for extracting nickel, cobalt, manganese and chromium from laterite nickel ore comprises the following steps:

[0009] (1) high pressure acid leaching is performed on the laterite nickel ore to obtain a leachate;

[0010] (2) neutralizing the leachate and obtaining iron-aluminum slag and iron-aluminum-removed liquid after solid-liquid separation;

[0011] (3) using hexavalent chromium adsorption resin to adsorb the iron and aluminum removal liquid to obtain the chromium removal liquid and the adsorbed resin, wherein the adsorbed resin contains chromium ions;

[0012] (4) using a desorption liquid to desorb the chromium ions in the adsorbed resin to obtain a chromium ion-containing enriched liquid; extracting the chromium-removed liquid to obtain an extracted liquid and a nickel-cobalt-manganese raffinate, wherein the extracted liquid contains impurity metal ions.

[0013] Preferably, in step (2), the pH of the neutralization reaction is 4 to 5, and the time is 1 to 4 hours.

[0014] Preferably, the resin in step (3) is a Cr-containing resin having a sulfonic acid group or a carboxyl group. 6+ Cation exchange resin with selective adsorption.

[0015] Preferably, the desorption liquid in step (4) is a dilute acid, more preferably sulfuric acid.

[0016] Preferably, the impurity metal ions in step (4) include Zn 2+ , Ca 2+ Mg 2+ .

[0017] Preferably, the extractant used to extract the chromium-removed liquid in step (4) is P204 or P507, the volume ratio of the organic phase to the aqueous phase during the extraction process is 1 to (5:1), the pH is 3-5, and the extraction time is 1-10 min.

[0018] Preferably, the above method further comprises electrochemically reducing and depositing the enriched solution containing chromium ions to obtain elemental chromium.

[0019] Preferably, the current density of electrochemical reduction deposition is 100-500A / m 2 , the electrolysis time is 1-5h, and the electrolysis temperature is 40-50℃.

[0020] Preferably, the above method further comprises adjusting the molar ratio of nickel, cobalt and manganese ions in the nickel, cobalt and manganese raffinate, and performing a nickel, cobalt and manganese precipitation operation to obtain a nickel, cobalt and manganese ternary precursor.

[0021] Preferably, the nickel-cobalt-manganese precipitation operation includes: contacting the nickel-cobalt-manganese raffinate after adjusting the molar ratio with a precipitant to react to obtain a nickel-cobalt-manganese ternary precursor. The precipitant is an alkaline solution, preferably ammonia water or sodium hydroxide.

[0022] The beneficial effects of the present invention are:

[0023] The present invention provides a method for extracting nickel, cobalt, manganese, and chromium from laterite nickel ore. The method utilizes a chromium ion adsorption resin to sequentially adsorb, desorb, and then electrodeposit hexavalent chromium in the leachate to separate and extract metallic chromium. Impurity ions are then extracted and separated from the chromium-removed solution to obtain a pure solution containing only nickel, cobalt, and manganese ions. This method effectively separates and recovers chromium from the leachate during the high-pressure acid leaching stage without the addition of a reducing agent, producing high-purity elemental chromium. Furthermore, further extraction of the chromium-removed solution yields a pure nickel, cobalt, and manganese solution for use in preparing nickel, cobalt, and manganese products. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings of the embodiments.

[0025] FIG1 is a flow chart of a method for extracting nickel, cobalt, manganese and chromium from laterite nickel ore according to the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] Under the high-temperature and high-pressure conditions of the acid leaching process for laterite nickel ore, the chromium in the nickel ore oxidizes to hexavalent chromium under the action of high-valent manganese minerals such as manganese dioxide. Existing technologies typically remove hexavalent chromium by adding reducing agents such as coal and sodium metabisulfite during the high-pressure acid leaching stage. However, this addition of reducing agents can inhibit the removal of iron from the leachate during the recovery of nickel, cobalt, and manganese products.

[0028] In order to solve this problem, an embodiment of the present invention provides a method for extracting nickel, cobalt, manganese and chromium from laterite nickel ore, as shown in FIG1 , comprising the following steps:

[0029] (1) High-pressure acid leaching is performed on the laterite nickel ore, wherein the leaching temperature is 180-270° C., the leaching time is 1-3 hours, and the acid-ore ratio is controlled to be 0.2-0.5 kg / t. No reducing agents such as sodium metabisulfite, sodium sulfite, and coal are added during the leaching process. After the leaching is completed, the leachate and leach residue are obtained by filtering. The leach residue can be directly landfilled or used for brick making;

[0030] (2) neutralizing the leachate with an alkaline compound at a pH of 4 to 5 for 1 to 4 hours, and obtaining iron-aluminum slag and a liquid after iron and aluminum removal after solid-liquid separation;

[0031] (3) Using Cr containing sulfonic acid or carboxyl groups 6+The cation exchange resin with selective adsorption absorbs the iron and aluminum removal liquid to obtain the chromium removal liquid and the adsorbed resin, and the adsorbed resin contains chromium ions;

[0032] (4) using dilute acid as a desorption liquid to desorb the chromium ions in the adsorbed resin to obtain a chromium ion-enriched solution; electrochemically reducing and depositing the chromium ion-enriched solution to obtain chromium element, and the current density of the electrochemical reduction deposition is 100-500A / m 2 , electrolysis time is 1-5h, electrolysis temperature is 40-50℃;

[0033] (5) Extracting the chromium-removed liquid with an extractant of P204 or P507, with an organic phase and aqueous phase volume ratio of 1 to (5:1), a pH of 3-5, and an extraction time of 1-10 min to obtain an extracted liquid and a nickel-cobalt-manganese raffinate. The extracted liquid contains Zn 2+ , Ca 2+ Mg 2+ and other impurity metal ions;

[0034] The nickel-cobalt-manganese ternary precursor is obtained by adjusting the molar ratio of nickel, cobalt, and manganese ions in the nickel-cobalt-manganese raffinate using analytically pure nickel sulfate, cobalt sulfate, and manganese sulfate. The molar ratio can be any of 1:1:1, 5:2:3, 6:2:2, and 8:1:1. The adjusted nickel-cobalt-manganese raffinate is then contacted with a precipitant to react. The precipitant is an alkaline solution, preferably aqueous ammonia and / or sodium hydroxide.

[0035] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below.

[0036] The main components of the laterite nickel ore used in the following examples include: Ni 1.67%, Co 0.08%, Mn 0.67%, Fe 37.11%, Al 3.83%, Cr 0.939%, Ca 0.13%, Mg 1.43%, and Zn 0.2-0.3%.

[0037] Chromium ion adsorption resin is prepared by Xi'an Lanxiao Technology New Materials Co., Ltd. and contains sulfonic acid groups and is chromium-sensitive. 6+ Cation exchange resin with selective adsorption.

[0038] Example 1

[0039] A method for extracting nickel, cobalt, manganese and chromium from laterite nickel ore comprises the following steps:

[0040] (1) mixing laterite nickel ore, water and 98% sulfuric acid, and performing high-pressure acid leaching in an autoclave, wherein the mass ratio of sulfuric acid to laterite nickel ore is 0.35 kg / t, the temperature in the autoclave is 250° C., the pressure is 4 MPa, and the leaching time is 1 h. After the leaching is completed, filtering is performed to obtain a leachate and a leach residue, wherein the Ni content in the leach residue is less than 0.05%, and the pH of the leachate is 0.53;

[0041] (2) adding dilute sodium hydroxide solution to the leachate to adjust the pH to 4.5, reacting for 2 hours, and filtering to obtain the iron and aluminum-free solution, wherein the residual iron and aluminum ion concentrations are both less than 5 ppm;

[0042] (3) Mix the iron and aluminum removal liquid with Cr 6+ The adsorption resin is contacted with the chromium removal liquid at a controlled flow rate of 1.5 BV / h. After adsorption is completed, the adsorbed resin and the chromium removal liquid are obtained. The hexavalent chromium content in the chromium removal liquid is measured to be less than 5 ppm. The adsorbed resin is desorbed with 5% sulfuric acid at a controlled flow rate of 2 BV / h to obtain a chromium ion-containing enriched liquid. The chromium ion-containing enriched liquid is subjected to electrochemical reduction deposition to obtain elemental chromium. The current density of the electrochemical reduction is 300 A / m 2 The electrolysis time is 5 hours, the electrolysis temperature is 40℃, the anode is a lead-based alloy plate, the cathode is a stainless steel plate, the cathode chromium stripping cycle is 48 hours, and the purity of the cathode stripped chromium metal is 99.8%.

[0043] (4) The chromium removal liquid was extracted with P204 as the extractant, the extraction pH was controlled at 3.5, the O / A ratio was 2:1, and the extraction time was 5 min to obtain the extracted liquid and the nickel, cobalt and manganese raffinate. The extracted liquid contained Zn 2+ , Ca 2+ Mg 2+ The content of impurity metal ions in the nickel-cobalt-manganese extract was measured to be less than 3 ppm. The molar ratio of nickel, cobalt, and manganese ions in the nickel-cobalt-manganese extract was adjusted to 5:2:3 using analytically pure nickel sulfate, cobalt sulfate, and manganese sulfate. The pH of the solution was adjusted to 11.2 using aqueous ammonia. The temperature was controlled at 60°C. After aging for 15 hours, the 523-type nickel-cobalt-manganese ternary precursor was obtained by filtration.

[0044] Example 2

[0045] A method for extracting nickel, cobalt, manganese and chromium from laterite nickel ore comprises the following steps:

[0046] (1) mixing laterite nickel ore, water and 98% sulfuric acid, and performing high-pressure acid leaching in an autoclave, wherein the mass ratio of sulfuric acid to laterite nickel ore is 0.35 kg / t, the temperature in the autoclave is 250° C., the pressure is 4 MPa, and the leaching time is 1 h. After the leaching is completed, filtering is performed to obtain a leachate and a leach residue, wherein the Ni content in the leach residue is less than 0.05%, and the pH of the leachate is 0.53;

[0047] (2) adding dilute sodium hydroxide solution to the leachate to adjust the pH to 5, reacting for 1 hour, filtering to obtain the iron and aluminum-removed solution, wherein the residual iron and aluminum ion concentrations are both less than 5 ppm;

[0048] (3) Mix the iron and aluminum removal liquid with Cr 6+ The adsorption resin is contacted with the chromium removal liquid at a controlled flow rate of 1 BV / h. After adsorption is completed, the adsorbed resin and the chromium removal liquid are obtained. The hexavalent chromium content in the chromium removal liquid is measured to be less than 5 ppm. The adsorbed resin is desorbed with 5% sulfuric acid at a controlled flow rate of 2 BV / h to obtain a chromium ion-containing enriched liquid. The chromium ion-containing enriched liquid is subjected to electrochemical reduction deposition to obtain elemental chromium. The current density of the electrochemical reduction is 500 A / m 2 , electrolysis time 1h, electrolysis temperature 50℃, anode uses lead-based alloy plate, cathode uses stainless steel plate, cathode chromium stripping cycle is 48h, and the purity of cathode stripped chromium metal is 99.6%.

[0049] (4) The chromium removal liquid was extracted with P204 as the extractant, the extraction pH was controlled at 5, the O / A ratio was 1:1, and the extraction time was 10 min to obtain the extracted liquid and the nickel, cobalt and manganese raffinate. The extracted liquid contained Zn 2+ , Ca 2+ Mg 2+ The content of impurity metal ions in the nickel-cobalt-manganese extract was measured to be less than 3 ppm. The molar ratio of nickel, cobalt, and manganese ions in the nickel-cobalt-manganese extract was adjusted to 6:2:2 using analytically pure nickel sulfate, cobalt sulfate, and manganese sulfate. The pH of the solution was adjusted to 11.5 using aqueous ammonia. The temperature was controlled at 50°C. After aging for 20 hours, the nickel-cobalt-manganese ternary precursor was obtained by filtration.

[0050] Example 3

[0051] A method for extracting nickel, cobalt, manganese and chromium from laterite nickel ore comprises the following steps:

[0052] (1) mixing laterite nickel ore, water and 98% sulfuric acid, and performing high-pressure acid leaching in an autoclave, wherein the mass ratio of sulfuric acid to laterite nickel ore is 0.35 kg / t, the temperature in the autoclave is 250° C., the pressure is 4 MPa, and the leaching time is 1 h. After the leaching is completed, filtering is performed to obtain a leachate and a leach residue, wherein the Ni content in the leach residue is less than 0.05%, and the pH of the leachate is 0.53;

[0053] (2) adding dilute sodium hydroxide solution to the leachate to adjust the pH to 4, reacting for 4 hours, and filtering to obtain a solution after iron and aluminum removal, wherein the residual iron and aluminum ion concentrations are both less than 5 ppm;

[0054] (3) Mix the iron and aluminum removal liquid with Cr 6+The adsorption resin is contacted with the chromium removal liquid at a controlled flow rate of 3BV / h. After adsorption is completed, the adsorbed resin and the chromium removal liquid are obtained. The hexavalent chromium content in the chromium removal liquid is measured to be less than 5ppm. The adsorbed resin is desorbed with 5% sulfuric acid at a controlled flow rate of 3BV / h to obtain a chromium ion-containing enriched liquid. The chromium ion-containing enriched liquid is subjected to electrochemical reduction deposition to obtain chromium element. The current density of the electrochemical reduction is 100A / m 2 The electrolysis time is 5 hours, the electrolysis temperature is 40℃, the anode is a lead-based alloy plate, the cathode is a stainless steel plate, the cathode chromium stripping cycle is 48 hours, and the purity of the cathode stripped chromium metal is 99.7%.

[0055] (4) The chromium removal liquid was extracted with P204 as the extractant, the extraction pH was controlled at 1, the O / A ratio was 5:1, and the extraction time was 1 min to obtain the extracted liquid and the nickel, cobalt and manganese raffinate. The extracted liquid contained Zn 2+ , Ca 2+ Mg 2+ The content of impurity metal ions in the nickel-cobalt-manganese extract was measured to be less than 3 ppm. The molar ratio of nickel, cobalt, and manganese ions in the nickel-cobalt-manganese extract was adjusted to 8:1:1 using analytically pure nickel sulfate, cobalt sulfate, and manganese sulfate. The pH of the solution was adjusted to 11.0 using aqueous ammonia. The temperature was controlled at 70°C. After aging for 10 hours, the nickel-cobalt-manganese ternary precursor was obtained by filtration.

[0056] The present invention's method for recovering chromium through electrodeposition avoids the extensive use of reducing agents and produces metallic chromium in elemental form, thereby increasing the added value of the entire process. The extraction process of the present invention directly prepares a nickel-cobalt-manganese ternary precursor, avoiding subsequent nickel-cobalt hydroxide (MHP) dissolution, extraction, and crystallization steps, shortening the process flow and reducing production costs. The entire process significantly reduces the emission of three wastes, has low equipment and operating requirements, and is suitable for industrial production.

[0057] It should be noted that the above embodiments all belong to the same inventive concept, and the description of each embodiment has its own focus. For any details not described in individual embodiments, reference may be made to the description in other embodiments.

[0058] The above-described embodiments merely illustrate the implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for extracting nickel, cobalt, manganese and chromium from laterite nickel ore, characterized in that: The following steps are involved: (1) high pressure acid leaching is performed on laterite nickel ore to obtain a leachate; (2) neutralizing the leaching solution, and obtaining iron-aluminum slag and iron-aluminum-removed liquid after solid-liquid separation; (3) using a hexavalent chromium adsorption resin to adsorb the iron and aluminum removal liquid to obtain a chromium removal liquid and an adsorbed resin; (4) using a desorption liquid to desorb the ions in the adsorbed resin to obtain an enriched liquid containing chromium ions; extracting the chromium-removed liquid to obtain an extracted liquid and a nickel-cobalt-manganese raffinate, wherein the extracted liquid contains impure metal ions.

2. The method for extracting nickel, cobalt, manganese and chromium from laterite nickel ore according to claim 1, characterized in that: The pH of the neutralization in step (2) is 4 to 5, and the time is 1 to 4 hours.

3. The method for extracting nickel, cobalt, manganese and chromium from laterite nickel ore according to claim 1, characterized in that: The resin in step (3) is a Cr-containing resin having a sulfonic acid group or a carboxyl group. 6+ Cation exchange resin with selective adsorption.

4. The method for extracting nickel, cobalt, manganese and chromium from laterite nickel ore according to claim 1, characterized in that: The desorption liquid in step (4) is dilute acid.

5. The method for extracting nickel, cobalt, manganese and chromium from laterite nickel ore according to claim 1, characterized in that: The impurity metal ions in step (4) include Zn 2+ , Ca 2+ Mg 2+ .

6. The method for extracting nickel, cobalt, manganese and chromium from laterite nickel ore according to claim 1, characterized in that: The extraction agent of step (4) is P204 or P507, the volume ratio of organic phase to aqueous phase during the extraction process is 1 to (5:1), the pH is 3-5, and the extraction time is 1-10 min.

7. The method for extracting nickel, cobalt, manganese and chromium from laterite nickel ore according to claim 1, characterized in that: The method also includes electrochemically reducing and depositing the enriched solution containing chromium ions to obtain chromium element.

8. The method for extracting nickel, cobalt, manganese and chromium from laterite nickel ore according to claim 7, characterized in that: The current density of the electrochemical reduction deposition is 100-500A / m 2 , the electrolysis time is 1-5h, and the electrolysis temperature is 40-50℃.

9. The method for extracting nickel, cobalt, manganese and chromium from laterite nickel ore according to claim 1, characterized in that: The method also includes adjusting the molar ratio of nickel, cobalt and manganese ions in the nickel, cobalt and manganese raffinate and performing a nickel, cobalt and manganese precipitation operation to obtain a nickel, cobalt and manganese ternary precursor.

10. The method for extracting nickel, cobalt, manganese and chromium from laterite nickel ore according to claim 9, characterized in that: The nickel-cobalt-manganese precipitation operation includes: contacting the nickel-cobalt-manganese raffinate with a precipitant to react to obtain a nickel-cobalt-manganese ternary precursor, wherein the precipitant is an alkaline solution.

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