WO2022179291A1 - Method for separating ferronickel from lateritic nickel ore leach solution and preparing iron phosphate, and application - Google Patents

Abstract

Disclosed in the present invention are a method for separating ferronickel from a lateritic nickel ore leach solution and preparing iron phosphate, and an application. The method comprises: adjusting the pH of a lateritic nickel ore leach solution to 0.5-1.5, dropwise adding a composite sulfide precipitant for reaction, adding a coagulating agent, and filtering to obtain nickel sulfide precipitates and a filtrate; then adding an oxidant and a phosphoric acid solution to the filtrate, adjusting the pH for reaction, and performing heating, concentration and crystallization to obtain iron phosphate. According to the present invention, a reaction process is controlled under a high acidity condition, and a reaction kinetics process is subtly controlled, so that one-step, efficient and low-cost separation of ferronickel is implemented, the separation effect is good, and the impurity content of iron phosphate is low.

Description

Method and application of separating ferronickel from laterite nickel ore leaching solution and preparing ferric phosphate technical field

The invention belongs to the technical field of laterite nickel ore hydrometallurgy, and particularly relates to a method and application for separating ferronickel from a laterite nickel ore leaching solution and preparing ferric phosphate.

Background technique

Laterite nickel ore resources are surface weathering crust deposits formed by weathering-leaching-sedimentation of nickel sulfide ore bodies. Aluminum, etc., have high usable value. At the same time, the world's laterite nickel ore resources are concentrated in the near equatorial regions, and most of them are close to the coast, which is convenient for transportation. In addition, the rapid development and progress of acid leaching technology of laterite nickel ore in recent years can further reduce its production cost.

The properties of nickel and iron are very similar and their sulfide solubility products are not much different. Therefore, the separation process of ferronickel is very difficult. Solvent extraction, ion exchange, electrolysis, etc. are often used in industrial practice.

Iron phosphate is mainly used to manufacture lithium iron phosphate battery materials, catalysts and ceramics.

How to obtain a more simple, efficient and low-cost method to separate ferronickel, and thereby prepare iron phosphate materials, needs further research and exploration.

SUMMARY OF THE INVENTION

The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a method and application for separating ferronickel from laterite nickel ore leaching solution and preparing ferric phosphate, which can reduce the cost of separation and make the process more efficient and simple.

According to one aspect of the present invention, a method for separating ferronickel from laterite nickel ore leaching solution is proposed, comprising the following steps:

(1) the pH of the laterite nickel ore leaching solution is adjusted to 0.5～1.5, the composite sulfide precipitant is added dropwise to react, and the coagulant is added, and filtered to obtain nickel sulfide precipitation and filtrate;

(2) in described filtrate, add oxidant and phosphoric acid solution, adjust pH after reaction, then heat and concentrate crystallization, obtain iron phosphate;

Wherein, the composite sulfide precipitating agent includes sulfide precipitating agent A and sulfide precipitating agent B, and the sulfide precipitating agent A is a mixture of sodium sulfide, potassium sulfide, lithium sulfide, ammonium sulfide, magnesium sulfide or hydrogen sulfide. One or more are prepared by mixing; the sulfide precipitant B is prepared by mixing one or more of sodium hydrosulfide, ammonium hydrosulfide or potassium hydrosulfide.

The whole process of the reaction is controlled under the condition of high acidity to inhibit the precipitation of iron sulfide. During the reaction, the thermodynamically unstable ferrous sulfide is quickly dissolved back into the solution and releases hydrogen sulfide gas, thereby realizing the separation of nickel and iron.

In some embodiments of the present invention, the ratio of the molar amount of sulfur in the composite sulfide precipitant to the molar amount of nickel in the laterite nickel ore leaching solution is (1-1.3):1

In some embodiments of the present invention, the composite sulfide precipitating agent is prepared by mixing the sulfide precipitating agent A and the sulfide precipitating agent B in a mass ratio of 1:(0.2-1.5).

In some embodiments of the present invention, the specific steps of step (1) are: adjusting the pH of the laterite nickel ore leaching solution to 0.5-1.5, and then adding the composite sulfide precipitant dropwise to react for 4-6 hours, and continuously adding during the period Compound sulfide precipitating agent and coagulant, and adding acid during the reaction to maintain the pH of the solution at 0.5-1.5.

In some embodiments of the present invention, in step (1), the coagulant is prepared by using alum and sodium polyacrylate in a molar ratio of (1-2):(1-2). Coagulants can further promote the formation of sulfide precipitates.

In some embodiments of the present invention, in step (1), the process of adjusting the pH of the laterite nickel ore leachate is: placing the laterite nickel ore leachate in a beaker, placing the beaker on a magnetic stirrer, adding a stirring magnet, Adjust the rotation speed to 100rpm～300rpm, and keep stirring, at the same time, add sodium bicarbonate solution dropwise to the laterite nickel ore leaching solution, and use a pH meter to monitor and control the pH of the solution in real time under constant stirring until the pH of the solution remains at within the range of 0.5 to 1.5.

In some embodiments of the present invention, in step (1), the filtration adopts Buchner funnel suction filtration.

In some embodiments of the present invention, in step (2), the oxidant is one of hydrogen peroxide, nitric acid, hypochlorous acid, oxygen or ozone; when the oxidant is hydrogen peroxide, the oxidant is The concentration of hydrogen oxide is 30% to 60%.

In some embodiments of the present invention, in step (2), the concentration of the phosphoric acid solution is 50% to 80%.

In some embodiments of the present invention, in step (2), the pH adjustment is to use at least one of concentrated ammonia water, ferric hydroxide or ferrous hydroxide to adjust the pH to 2-4.

In some embodiments of the present invention, in step (2), the reaction time is 3-5 h.

In some embodiments of the present invention, in step (2), the heating is heated to 85-110° C. at a heating rate of 3-5° C./min.

In some embodiments of the present invention, in step (2), after the concentrated crystallization, the process of washing the iron phosphate with deionized water is further included.

The present invention also provides an iron phosphate prepared by the above method.

The present invention also proposes a lithium iron phosphate, which is prepared from the raw materials including the above-mentioned iron phosphate.

The present invention also provides a method for preparing lithium iron phosphate, which includes the following steps: preparing a lithium carbonate solution and an ascorbic acid solution, dispersing the iron phosphate in water to obtain an iron phosphate suspension, and dispersing the iron phosphate suspension, The lithium carbonate solution and the ascorbic acid solution are evenly mixed, stirred, and then heated for reaction to obtain the lithium iron phosphate.

In some embodiments of the present invention, the stirring time is 2-4 hours.

In some embodiments of the present invention, the temperature of the heating reaction is 150-250° C., and the time is 20-30 h.

According to a preferred embodiment of the present invention, it has at least the following beneficial effects:

1. From the technical principle, the sulfide solubility products of nickel and iron are not much different, so the separation coefficient of the two sulfide precipitations is not large, but the present invention controls the reaction process under high acidity conditions, ingeniously. The reaction kinetics process is controlled, so as to realize one-step high-efficiency and low-cost separation of nickel and iron, with good separation effect and low impurity content of iron phosphate.

2. The sulfide precipitation method adopted in the present invention can not only be applied to the sulfuric acid system, but also can be applied to other systems such as hydrochloric acid, and has a wide range of applicability, so it has practical significance for the improvement of the enrichment process for the sulfide separation research of ferronickel.

3. The present invention prepares the precursor iron phosphate of lithium iron phosphate through a simple separation and preparation method, and finally prepares lithium iron phosphate, and its first charge-discharge specific capacity can reach more than 164mAh/g.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, wherein:

FIG. 1 is a SEM image of the iron phosphate prepared in Example 1 of the present invention.

Detailed ways

The concept of the present invention and the technical effects produced will be clearly and completely described below with reference to the embodiments, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts are all within the scope of The scope of protection of the present invention.

Example 1

The present embodiment utilizes the sulfidation method to separate ferronickel from the leaching solution of laterite nickel ore and prepares iron phosphate and lithium iron phosphate, and the specific process is:

(1) Preparation of composite sulfide precipitant: get sodium sulfide and potassium sulfide to mix and prepare sulfide precipitant A, get sodium hydrosulfide and ammonium hydrosulfide to mix and prepare sulfide precipitant B, mix sulfide precipitant A with sulfur The precipitant B is mixed and prepared into a composite sulfide precipitant, which is ready for use; at the same time, the solid alum and the solid sodium polyacrylate are prepared according to the molar ratio of 2:1 to prepare a coagulant to promote the precipitation process of the sulfide;

(2) Place the laterite nickel ore leaching solution in a beaker, place the beaker on a magnetic stirrer, add a stirring magnet, adjust the rotational speed to 100 rpm, and continuously stir, and at the same time, add hydrogen carbonate dropwise to the laterite nickel ore leaching solution sodium solution, and use a pH meter to monitor and control the pH of the solution in real time under constant stirring until the pH of the solution is maintained at about 0.5;

(3) At room temperature, slowly add the composite sulfide precipitant to the laterite nickel ore leaching solution dropwise, and continuously add acid to the solution to keep the pH of the solution at about 0.5;

(4) A coagulant is added during the reaction to further promote the formation of sulfide precipitation. The whole process of the reaction should be controlled under high acidity conditions to inhibit the precipitation of iron sulfide. During the reaction, the thermodynamically unstable ferrous sulfide will be quickly dissolved back into the solution and release hydrogen sulfide gas, thereby To achieve the separation of nickel and iron;

(5) React for 4 hours, and continuously add compound sulfide precipitant and coagulant under the condition that the pH of the solution is controlled to be about 0.5 to ensure that the precipitation reaction is complete. After the reaction is completed, the solution is filtered through a Buchner funnel. Obtain nickel sulfide precipitation and filtrate;

(6) adding hydrogen peroxide with a concentration of 30% and a phosphoric acid solution of 50% to the filtrate, adjusting the pH to 2 with concentrated ammonia, reacting for 3h, heating to 85°C at a heating rate of 3°C/min, and concentrating the crystallization, Wash the precipitate with deionized water to prepare iron phosphate, which is used as a precursor for preparing lithium iron phosphate for subsequent use;

(7) get an appropriate amount of lithium carbonate, ascorbic acid and dissolve in water respectively, obtain lithium carbonate solution and ascorbic acid solution, and disperse iron phosphate in water to obtain iron phosphate suspension, mix lithium carbonate solution, ascorbic acid solution and iron phosphate suspension After uniform, put it into the reaction kettle, continue to stir for 2 hours, then transfer the reaction kettle solution to a hydrothermal reaction oven, and react at 150 ° C for 20 hours to prepare lithium iron phosphate.

Fig. 1 is the SEM image of the iron phosphate prepared by the present embodiment, as can be seen from the figure, the prepared iron phosphate material has a regular morphology, uniform particle size, no obvious agglomeration, and is relatively fluffy and has pores, which is conducive to the follow-up Preparation of Lithium Iron Phosphate.

Example 2

The present embodiment utilizes the sulfidation method to separate ferronickel from the leaching solution of laterite nickel ore and prepares iron phosphate and lithium iron phosphate, and the specific process is:

(1) Preparation of composite sulfide precipitating agent: get potassium sulfide, lithium sulfide and ammonium sulfide and mix and prepare sulfide precipitating agent A, get sodium hydrosulfide, ammonium hydrosulfide and potassium hydrosulfide and mix and prepare sulfide precipitating agent B. Sulfide precipitating agent A and sulfide precipitating agent B are mixed to prepare a composite sulfide precipitating agent, which is ready for use; at the same time, solid alum and solid sodium polyacrylate are prepared in a molar ratio of 1:1 to prepare a coagulant to promote sulfide the precipitation process;

(2) Place the laterite nickel ore leaching solution in a beaker, place the beaker on a magnetic stirrer, add a stirring magnet, adjust the rotational speed to 200 rpm, and continuously stir, and at the same time, add hydrogen carbonate dropwise to the laterite nickel ore leaching solution sodium solution, and use a pH meter to monitor and control the pH of the solution in real time under constant stirring until the pH of the solution remains around 1;

(3) at room temperature, slowly add the composite sulfide precipitant to the laterite nickel ore leaching solution dropwise, and continuously add acid to the solution to keep the pH of the solution at about 1;

(4) A coagulant is added during the reaction to further promote the formation of sulfide precipitation. The whole process of the reaction should be controlled under high acidity conditions to inhibit the precipitation of iron sulfide. During the reaction, the thermodynamically unstable ferrous sulfide will be quickly dissolved back into the solution and release hydrogen sulfide gas, thereby To achieve the separation of nickel and iron;

(5) React for 5 hours, and continuously add compound sulfide precipitant and coagulant under the condition that the pH of the solution is controlled to be about 1 to ensure that the precipitation reaction is completed. After the reaction is completed, the solution is filtered through a Buchner funnel. Obtain nickel sulfide precipitation and filtrate;

(6) adding hydrogen peroxide with a concentration of 45% and a phosphoric acid solution of 65% to the filtrate, adjusting the pH to 3 with concentrated ammonia, reacting for 4h, heating to 100°C at a heating rate of 4°C/min, and concentrating the crystallization, Wash the precipitate with deionized water to prepare iron phosphate, which is used as a precursor for preparing lithium iron phosphate for subsequent use;

(7) get an appropriate amount of lithium carbonate, ascorbic acid and dissolve in water respectively, obtain lithium carbonate solution and ascorbic acid solution, and disperse iron phosphate in water to obtain iron phosphate suspension, mix lithium carbonate solution, ascorbic acid solution and iron phosphate suspension After uniform, put it into the reaction kettle, continue to stir for 3 hours, then transfer the reaction kettle solution to a hydrothermal reaction oven, and react at 200 ° C for 25 hours to prepare lithium iron phosphate.

Example 3

The present embodiment utilizes the sulfidation method to separate ferronickel from the leaching solution of laterite nickel ore and prepares iron phosphate and lithium iron phosphate, and the specific process is:

(1) Preparation of composite sulfide precipitating agent: get ammonium sulfide, magnesium sulfide and hydrogen sulfide to mix and prepare sulfide precipitating agent A, take ammonium hydrosulfide as sulfide precipitating agent B, mix sulfide precipitating agent A and sulfide precipitating agent B is mixed and prepared into a composite sulfide precipitation agent, which is ready for use; at the same time, solid alum and solid sodium polyacrylate are prepared according to the molar ratio of 1:2 to prepare a coagulant to promote the precipitation process of sulfide;

(2) Place the laterite nickel ore leaching solution in a beaker, place the beaker on a magnetic stirrer, add a stirring magnet, adjust the rotational speed to 300 rpm, and continuously stir, and at the same time, add hydrogen carbonate dropwise to the laterite nickel ore leaching solution sodium solution, and use a pH meter to monitor and control the pH of the solution in real time under constant stirring until the pH of the solution remains around 1.5;

(3) At room temperature, slowly add the composite sulfide precipitant to the laterite nickel ore leaching solution dropwise, and continuously add acid to the solution to keep the pH of the solution at about 1.5;

(4) A coagulant is added during the reaction to further promote the formation of sulfide precipitation. The whole process of the reaction should be controlled under high acidity conditions to inhibit the precipitation of iron sulfide. During the reaction, the thermodynamically unstable ferrous sulfide will be quickly dissolved back into the solution and release hydrogen sulfide gas, thereby To achieve the separation of nickel and iron;

(5) React for 6 hours, and continuously add compound sulfide precipitant and coagulant under the condition that the pH of the solution is controlled to be about 1.5 to ensure that the precipitation reaction is completed. After the reaction is completed, the solution is filtered through a Buchner funnel. Obtain nickel sulfide precipitation and filtrate;

(6) adding hydrogen peroxide with a concentration of 60% and a phosphoric acid solution of 80% to the filtrate, adjusting the pH to 4 with concentrated ammonia, reacting for 5h, heating to 110°C at a heating rate of 5°C/min, and concentrating the crystallization, Wash the precipitate with deionized water to prepare iron phosphate, which is used as a precursor for preparing lithium iron phosphate for subsequent use;

(7) get an appropriate amount of lithium carbonate, ascorbic acid and dissolve in water respectively, obtain lithium carbonate solution and ascorbic acid solution, and disperse iron phosphate in water to obtain iron phosphate suspension, mix lithium carbonate solution, ascorbic acid solution and iron phosphate suspension After uniform, put it into the reaction kettle, continue to stir for 4 hours, then transfer the reaction kettle solution to a hydrothermal reaction oven, and react at 250 ° C for 30 hours to prepare lithium iron phosphate.

Comparative ratio

This comparative example adopts the solvent extraction method to separate ferronickel from the leaching solution of laterite nickel ore and prepares iron phosphate and lithium iron phosphate. The difference from Example 1 is that the principle of separating ferronickel is different, and the specific process is:

Using laterite nickel ore leachate solution as raw material, with V(O): V(A)=3:1 P507 extractant (saponification rate 50%) in sulfuric acid system (control pH=2) to extract iron ions, at room temperature 3-stage countercurrent extraction is adopted, and after 10 minutes of reaction, the organic phase can be recycled to separate ferronickel; then phosphoric acid is added to react with iron to prepare ferric phosphate products; lithium carbonate solution, ascorbic acid solution and ferric phosphate suspension are mixed uniformly, put into a reaction kettle, fully stirred, and then transferred to a hydrothermal reaction oven to fully react to prepare lithium iron phosphate.

Finished product quality

Table 1 is the impurity element content of the iron phosphate products prepared by Examples 1-3 and Comparative Examples, and the specific data are obtained by ICP-AES equipment testing.

Impurity content in table 1 iron phosphate product

Impurity element content (%) Example 1 Example 2 Example 3 Comparative ratio

Al 0.004 0.001 0.006 0.03 Cu 0.005 0.0007 0.003 0.05 Cd 0.0004 0.0002 0.0005 0.004 Mg 0.005 0.002 0.004 0.02 Ni 0.02 0.006 0.03 0.14 Insolubles 0.006 0.002 0.008 0.26

It can be seen from Table 1 that the impurity content of the iron phosphate product prepared in Examples 1-3 is obviously lower than that of the comparative example, especially Example 2.

Electrochemical performance

Table 2 shows the electrochemical properties of lithium iron phosphate batteries prepared in Examples 1-3 and Comparative Examples, and the specific data are obtained by testing equipment such as electrochemical workstations.

Table 2 Comparison of electrochemical properties of lithium iron phosphate batteries

Electrochemical performance Example 1 Example 2 Example 3 Comparative ratio First charge-discharge specific capacity (mAh/g) 164.3 165.2 164.2 135.7 First charge-discharge efficiency (%) 95.8 97.6 96.1 92.3 1C cycle 1000 times discharge capacity retention rate (%) 97.7 98.6 97.9 88.9

It can be seen from Table 2 that the electrochemical performance of the lithium iron phosphate product prepared in Examples 1-3 is obviously better than that of the comparative example, especially Example 2.

The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned embodiments, and within the scope of knowledge possessed by those of ordinary skill in the art, various Variety. Furthermore, the embodiments of the present invention and features in the embodiments may be combined with each other without conflict.

Claims (10)

A method for separating ferronickel from laterite nickel ore leaching solution, is characterized in that, comprises the following steps: (1) the pH of the laterite nickel ore leaching solution is adjusted to 0.5～1.5, the composite sulfide precipitant is added dropwise to react, and the coagulant is added, and filtered to obtain nickel sulfide precipitation and filtrate; (2) in described filtrate, add oxidant and phosphoric acid solution, adjust pH after reaction, then heat and concentrate crystallization, obtain iron phosphate; Wherein, the composite sulfide precipitating agent includes sulfide precipitating agent A and sulfide precipitating agent B, and the sulfide precipitating agent A is a mixture of sodium sulfide, potassium sulfide, lithium sulfide, ammonium sulfide, magnesium sulfide or hydrogen sulfide. One or more are prepared by mixing; the sulfide precipitant B is prepared by mixing one or more of sodium hydrosulfide, ammonium hydrosulfide or potassium hydrosulfide. The method according to claim 1, wherein the specific steps of step (1) are: adjusting the pH of the laterite nickel ore leaching solution to 0.5-1.5, and then adding the composite sulfide precipitant dropwise to react for 4-6h , the compound sulfide precipitant and the coagulant are continuously added during the reaction, and acid is added to maintain the pH of the solution at 0.5 to 1.5 during the reaction. The method according to claim 1, characterized in that, in step (1), the coagulant is prepared by using alum and sodium polyacrylate in a molar ratio of (1-2): (1-2). The method according to claim 1, wherein in step (2), the oxidant is one of hydrogen peroxide, nitric acid, hypochlorous acid, oxygen or ozone; when the oxidant is hydrogen peroxide , the concentration of the hydrogen peroxide is 30% to 60%. The method according to claim 1, wherein in step (2), the pH adjustment is to adjust pH to 2-4 by at least one of concentrated ammonia water, ferric hydroxide or ferrous hydroxide. The method according to claim 1, characterized in that, in step (2), the reaction time is 3-5h. The method according to claim 1, wherein in step (2), the heating is heated to 85-110°C at a temperature increase rate of 3-5°C/min. A ferric phosphate, characterized in that it is prepared by the method of any one of claims 1-7. A lithium iron phosphate, characterized in that it is prepared from the raw material comprising the iron phosphate of claim 8. The preparation method of lithium iron phosphate according to claim 9, is characterized in that, comprises the following steps: prepare lithium carbonate solution and ascorbic acid solution, place described iron phosphate in water and disperse to obtain iron phosphate suspension, and described iron phosphate The suspension, the lithium carbonate solution and the ascorbic acid solution are evenly mixed, stirred, and then heated for reaction to obtain the lithium iron phosphate.

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