WO2022161087A1 - Method for separating nickel and iron from nickel-iron alloy and use - Google Patents

Abstract

The present invention belongs to the field of hydrometallurgy. Disclosed are a method for separating nickel and iron from a nickel-iron alloy and use. The method comprises the following steps: dissolving a nickel-iron alloy in an acid solution, filtering, and collecting the filtrate to obtain an acidic nickel-iron solution; adjusting the pH of the acidic nickel-iron solution, heating, stirring, adding iron powder, and continuing heating and stirring to obtain sponge nickel and nickel precipitation mother liquor; subjecting the nickel precipitation mother liquor to oxidation and iron precipitation to obtain iron hydroxide slag and an iron precipitation mother liquor; and dissolving sponge nickel in sulfuric acid, filtering, collecting the filtrate, raising the temperature, and adjusting the pH, so as to obtain a nickel sulfate solution. In the present invention, after the nickel-iron alloy is dissolved using the acid solution, nickel in the solution is displaced by iron powder to obtain the sponge nickel, the nickel precipitation mother liquor is oxidized to produce iron hydroxide, the nickel content is less than 0.4%, the iron precipitation mother liquor can be returned to a leaching section, and the sponge nickel can be subjected to acid dissolution, impurity removal, and evaporative crystallization to obtain a battery-grade nickel sulphate product.

Description

A kind of method and application of separating nickel and iron from nickel-iron alloy technical field

The invention belongs to the field of hydrometallurgy, and in particular relates to a method and application for separating nickel and iron from nickel-iron alloys.

Background technique

In recent years, with the rapid development of the lithium battery new energy industry, lithium ion batteries have been widely used in various electronic devices due to their high operating voltage, high energy density, low self-discharge, long life, and no memory effect. Unlike other types of chemical power systems, the positive and negative materials of lithium-ion batteries are still innovating and developing. According to the current market analysis, NCM/NCA (battery cathode material) ternary materials occupy more than 50% of the market share, and the demand for nickel is increasing day by day.

Worldwide, nickel production capacity is gradually in short supply. The supply of nickel sulfate is obviously insufficient. The ternary precursor factory purchases nickel raw materials such as nickel beans, nickel powder, nickel plates, MHP (mixed nickel cobalt hydroxide), etc., and obtains battery-grade nickel sulfate through processing and refining to alleviate the shortage of raw materials. condition. In order to solve the problem of insufficient nickel raw materials in battery materials, the development of new nickel raw materials to prepare battery-grade nickel sulfate has become an urgent problem to be solved. At present, nickel products in domestic and foreign markets are mostly produced in the form of elemental nickel and nickel-iron alloy, and a few are produced in the form of nickel sulfate and MHP. The process of preparing battery-grade nickel sulfate from elemental nickel is simple, directly adding sulfuric acid to dissolve, and simply removing impurities. But elemental nickel is expensive and not cost-effective. The nickel-iron alloy is not only abundant in supply, but also low in price, but because it contains a large amount of iron impurities, the separation requires a large amount of auxiliary material consumption, and there has been no good breakthrough in technology.

The related art discloses a method and system for extracting nickel oxide from laterite nickel ore. The involved method is to melt and granulate nickel-iron alloy, then perform selective oxidation roasting, and then perform ammonia leaching-ammonia-steaming-calcining treatment to obtain oxidation Nickel products. This process is feasible, which can improve the utilization value of nickel-iron alloy and reduce the production cost of nickel. However, due to the large consumption of auxiliary materials and high energy consumption, it is not easy to promote.

The related art also discloses using nickel-containing pig iron as a raw material, leaching ferronickel through a mixed acid of phosphoric acid and sulfuric acid/hydrochloric acid, obtaining a solution, adding an oxidant for oxidation, and adding lye to precipitate ferric phosphate to obtain a mixed solution of nickel sulfate and sodium sulfate/ammonium sulfate, The solution is then subjected to an extraction-stripping process to obtain a battery-grade nickel sulfate solution. The quality of the iron phosphate obtained by this process is poor and cannot reach the battery level, and the nickel sulfate has to go through the extraction-stripping process, which has high cost, low benefit and relatively high impurity content.

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 nickel and iron from nickel-iron alloy. The method obtains iron hydroxide by acid-dissolving nickel-iron alloy, replacing sponge nickel, oxidizing iron and washing slag; The battery grade nickel sulfate is obtained by evaporating and crystallization, the method has low energy consumption, low cost, simple process, and realizes the efficient resource utilization of nickel and iron.

To achieve the above object, the present invention adopts the following technical solutions:

A method for separating nickel and iron from nickel-iron alloy, comprising the steps of:

(1) nickel-iron alloy is dissolved in acid solution, filter, get filtrate, obtain acid nickel-iron solution;

(2) pH is adjusted by the acid nickel-iron solution, heating, stirring, adding iron powder and continuing to heat and stir to obtain nickel sponge and precipitation nickel mother liquor;

(3) carry out oxidizing and precipitating iron with described nickel-precipitating mother liquor, obtain ferric hydroxide slag and precipitating iron mother liquor;

(4) dissolving the nickel sponge in sulfuric acid, filtering, collecting the filtrate, heating up, adjusting the pH, and obtaining a nickel sulfate solution.

Preferably, in step (1), the nickel-iron alloy is obtained by reducing and roasting laterite nickel ore, and the nickel-iron alloy has a nickel content of 15% to 40% and an iron content of 60% to 85%; wherein, The total content of impurities is less than 2%.

Preferably, in step (1), the acid solution is at least one of sulfuric acid or hydrochloric acid.

Preferably, in step (1), the dissolving temperature is 20°C to 95°C, more preferably 50°C to 95°C, and more preferably 60°C to 85°C.

Preferably, in step (1), the concentration of H ⁺ in the acid solution is 1-12 mol/L, more preferably 2-8 mol/L, and more preferably 3-6 mol/L.

Preferably, in step (1), the solid-to-liquid ratio of the nickel-iron alloy to the acid solution is 1:(1-100) g/mL, more preferably 1:(1-50) g/mL, more preferably 1 : (1～30) g/mL.

Preferably, in step (2), the pH adjustment is to adjust the pH to 1.0-5.0, further preferably, the pH is 1.0-3.5, more preferably, the pH is 1.5-3.0.

More preferably, in step (2), the pH adjuster used in the process of adjusting the pH to 1.0-5.0 is at least one of nickel-iron alloy, sodium hydroxide, sodium carbonate or ammonia water. More preferably, the pH adjuster is a nickel-iron alloy. Reduce the generation of impurities and increase the leaching rate of nickel and iron.

Preferably, in step (2), the heating temperature is 30°C to 90°C, more preferably 50°C to 90°C, and more preferably 60°C to 80°C.

Preferably, in step (2), the stirring time is 0.5-20 h, more preferably 1-10 h, and more preferably 1-5 h.

Preferably, in step (2), the amount of iron powder added is 0.5 to 5 times the theoretical amount required for nickel replacement, more preferably 0.5 to 3 times, and more preferably 0.7 to 2 times.

Preferably, in step (2), the heating temperature is 30-100°C, more preferably 50-90°C, and more preferably 50-80°C.

Preferably, in step (3), the oxidant used in the process of oxidizing iron precipitation is at least one of hydrogen peroxide, oxygen, air, ozone or sodium persulfate.

Preferably, in step (3), the immersed iron mother liquor is an acidic solution containing ferric iron, and the immersed iron mother liquor is returned to step (1) to continue cyclic leaching, and can generate ferrous iron with iron in the nickel-iron alloy.

Preferably, in step (4), the sulfuric acid concentration is 0.1-10 mol/L, more preferably 0.5-8 mol/L, and more preferably 0.5-5 mol/L.

Preferably, in step (4), the temperature of the temperature increase is 30°C to 90°C, more preferably 50°C to 80°C, and more preferably 60°C to 80°C.

Preferably, in step (4), the pH adjustment is to adjust the pH to 2-6, more preferably 3-5, and more preferably 4-5.

Preferably, in step (4), the reagent for adjusting pH includes but is not limited to at least one of sodium carbonate, nickel carbonate, ammonium carbonate or sodium hydroxide.

Preferably, after step (4), it also includes a process of evaporating and crystallizing the nickel sulfate solution to obtain battery-grade nickel sulfate.

More preferably, the temperature of the evaporative crystallization is 30°C to 150°C, more preferably 30°C to 100°C, and more preferably 50°C to 90°C.

More preferably, the evaporative crystallization time is 1-20 h, more preferably 2-15 h, and more preferably 3-10 h.

The present invention also provides the application of the above method in recovering non-ferrous metals.

The present invention also provides the application of the above-mentioned method in the preparation of pigments, medicines or catalysts.

With respect to the prior art, the beneficial effects of the present invention are as follows:

1. the present invention uses acid solution to dissolve the nickel-iron alloy, replaces the nickel in the solution by iron powder to obtain sponge nickel, and generates iron hydroxide after the oxidation of the precipitation nickel mother liquor, and the nickel content in the iron hydroxide is lower than 0.4%, and the precipitation iron mother liquor is lower than 0.4%. Then it can be returned to the leaching section. After acid dissolution, impurity removal, and evaporation and crystallization, the sponge nickel can obtain battery-grade nickel sulfate products (the purity of nickel sulfate is above 99.5%). It exists in the form of ferric hydroxide and has certain economic value, and nickel is resourced to obtain battery-grade nickel sulfate.

2. The process of the invention is simple, the cost is low, the solution can be leached cyclically, the acid consumption is low, and the industrial application has great practicability.

Description of drawings

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

FIG. 1 is a process flow diagram of Embodiment 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 method for separating nickel and iron from nickel-iron alloy of the present embodiment includes the following steps:

(1) Weigh 200 g of nickel-iron alloy (iron: 63.28%, nickel: 35.51%, Co: 0.34%, Mn: 0.09%, Si: 0.27%, Cr: 0.05%, Ca: 0.006%, Mg: 0.004%, Cu : 0.03%, S: 0.21%, P: 0.03%), add 2.5mol/L sulfuric acid solution according to the solid-to-liquid ratio of 1:8 g/mL, dissolve at 80 °C, filter, and collect the filtrate to obtain acid nickel iron Leachate;

(2) Add the nickel-iron leaching solution obtained in step (1) at 80°C to adjust the pH of the solution to 1.5, adjust the pH for 2 hours, and add 0.8 times the theoretical amount of iron powder required to replace nickel at 70°C , filter to obtain sponge nickel and precipitation nickel mother liquor after the replacement;

(3) adding hydrogen peroxide to the precipitation nickel mother liquor obtained in step (2), ferric hydroxide can be generated by hydrolysis after oxidizing ferrous iron in the solution to ferric iron, filtering to obtain ferric hydroxide slag and precipitation iron mother liquor, and the obtained nickel The iron mother liquor returns to step (1) and continues to dissolve the nickel-iron alloy;

(4) adding 1.0mol/L sulfuric acid to the sponge nickel obtained in step (2) and dissolving, after filtration, obtain crude product nickel sulfate solution;

(5) at 70 DEG C, the crude product nickel sulfate solution that step (4) is obtained, adding mass concentration is that the sodium carbonate solution of 25% adjusts pH to about 4.0, and filters to obtain impurity removal slag and nickel sulfate solution;

(6) Evaporating and crystallizing the nickel sulfate solution obtained in step (5) at 80° C. for 8 hours to obtain battery-grade nickel sulfate crystals.

Fig. 1 is the process flow diagram of the embodiment of the present invention 1, can be obtained from Fig. 1, use acid solution to carry out acid-dissolving to nickel-iron alloy, after obtaining the acid nickel-iron solution with higher nickel-iron concentration, use iron powder to dissolve in the solution Nickel ions are replaced with sponge nickel, and the obtained nickel precipitation mother solution is oxidized to generate iron hydroxide slag; sponge nickel is dissolved in dilute sulfuric acid, impurity removal, and evaporative crystallization to prepare battery-grade nickel sulfate crystals.

Example 2

The method for separating nickel and iron from nickel-iron alloy of the present embodiment includes the following steps:

(1) Weigh 150 g of nickel-iron alloy (iron: 83.12%, nickel: 15.45%, Co: 0.51%, Mn: 0.05%, Si: 0.36%, Cr: 0.09%, Ca: 0.012%, Mg: 0.008%, Cu : 0.05%, S: 0.22%, P: 0.01%) according to the mass-solid-to-liquid ratio of 1:6g/mL, add 2.5mol/L sulfuric acid solution, dissolve at 85 ℃, filter, take the filtrate to obtain acid nickel iron leachate;

(2) adding sodium carbonate to the acidic nickel-iron leaching solution obtained in step (1) at 70° C. to adjust the pH of the solution to 1.8, adjusting the pH for 3 hours, and adding 0.9 times the theoretical amount of iron required to replace nickel at 60° C. Powder, filter to obtain sponge nickel and nickel sink mother liquor after replacement;

(3) oxygen is passed through the nickel precipitation mother liquor obtained in step (2), the ferrous iron in the solution can be oxidized to trivalent iron and then hydrolyzed to generate ferric hydroxide, and the ferric hydroxide slag and the precipitation iron mother liquor are obtained by filtration, and the obtained nickel The iron mother liquor returns to step (1) and continues to dissolve the nickel-iron alloy;

(4) adding 1.2mol/L sulfuric acid to the sponge nickel obtained in step (2) and dissolving, after filtration, obtain a crude product nickel sulfate solution;

(5) adding the crude product nickel sulfate solution obtained in step (4) at 80° C., adding mass concentration of 5% sodium hydroxide solution to adjust pH to about 4.5, and filtering to obtain impurity removal slag and nickel sulfate solution;

(6) Evaporating and crystallizing the nickel sulfate solution obtained in step (5) at 85° C. for 6 hours to obtain battery-grade nickel sulfate crystals.

Example 3

The method for separating nickel and iron from nickel-iron alloy of the present embodiment includes the following steps:

(1) Weigh 100 g of nickel-iron alloy (iron 67.22%, nickel 30.79%, Co: 0.47%, Mn: 0.08%, Si: 0.25%, Cr: 0.09%, Ca: 0.008%, Mg: 0.005%, Cu: 0.04 %, S: 0.29%, P: 0.05%) according to the solid-to-liquid ratio of 1:8 g/mL, add 2mol/L hydrochloric acid solution, dissolve at 65 ° C, filter, and take the filtrate to obtain acid nickel iron leachate;

(2) Add the acidic nickel-iron leaching solution obtained in step (1) at 80°C to adjust the pH of the solution to 2.0, adjust the pH for 4h, add 0.85 times the theoretical amount of iron powder required for nickel replacement at 65°C, and replace After finishing, filter to obtain sponge nickel and nickel sinking mother liquor;

(3) passing the precipitation nickel mother liquor obtained in step (2) into the air, the ferrous iron in the solution can be oxidized to ferric iron and then hydrolyzed to generate ferric hydroxide, and the ferric hydroxide slag and the precipitation iron mother liquor are obtained by filtration, and the ferronickel mother liquor Return to step (1) and continue to dissolve the nickel-iron alloy;

(4) adding 0.5mol/L sulfuric acid to the sponge nickel obtained in step (2) and dissolving, after filtration, obtain crude product nickel sulfate solution;

(5) adding the crude product nickel sulfate solution obtained in step (4) at 75° C., adding mass concentration of 30% ammonium carbonate solution to adjust pH to about 4.2, and filtering to obtain impurity removal residue and nickel sulfate solution;

(6) Evaporating and crystallizing the nickel sulfate solution obtained in step (5) at 90° C. for 3 hours to obtain battery-grade nickel sulfate crystals.

Example 4

The method for separating nickel and iron from nickel-iron alloy of the present embodiment includes the following steps:

(1) Weigh 120 g of nickel-iron alloy (iron: 83.12%, nickel: 15.45%, Co: 0.51%, Mn: 0.05%, Si: 0.36%, Cr: 0.09%, Ca: 0.012%, Mg: 0.008%, Cu : 0.05%, S: 0.22%, P: 0.01%) according to the solid-liquid ratio of 1:8g/mL, add 1.5mol/L hydrochloric acid solution, dissolve at 85 ℃, filter, collect the filtrate, and obtain acid nickel iron leachate;

(2) Add the nickel-iron leaching solution obtained in step (1) at 70°C to adjust the pH of the solution to 2.5, adjust the pH for 5h, add iron powder 1.0 times the theoretical amount required for nickel replacement at 70°C, and replace After finishing, filter to obtain sponge nickel and nickel sinking mother liquor;

(3) adding sodium persulfate to the nickel precipitation mother liquor obtained in step (2), after the ferrous iron in the solution can be oxidized to ferric iron and then hydrolyzed to generate ferric hydroxide, filtered to obtain ferric hydroxide slag and precipitation iron mother liquor, ferronickel Mother liquor returns to step (1) and continues to dissolve nickel-iron alloy;

(4) adding 1.5mol/L sulfuric acid to the sponge nickel obtained in step (2) and dissolving, after filtration, obtain crude product nickel sulfate solution;

(5) at 70 DEG C, the crude product nickel sulfate solution obtained in step (4) is added with nickel carbonate solution to adjust pH to about 4.5, and filtered to obtain impurity removal slag and nickel sulfate solution;

(6) Evaporating and crystallizing the nickel sulfate solution obtained in step (5) at 80° C. for 7 hours to obtain battery-grade nickel sulfate crystals.

Example 5

The method for separating nickel and iron from nickel-iron alloy of the present embodiment includes the following steps:

(1) Weigh 300 g of nickel-iron alloy (iron: 86.55%, nickel: 12.36%, Co: 0.29%, Mn: 0.09%, Si: 0.15%, Cr: 0.07%, Ca: 0.005%, Mg: 0.003%, Cu : 0.05%, S: 0.23%, P: 0.02%) according to the solid-liquid ratio of 1:8g/mL, add 2.0mol/L sulfuric acid solution, dissolve at 75 ° C for a period of time, and filter to obtain acid nickel-iron leachate;

(2) adding sodium hydroxide to the nickel-iron leaching solution obtained in step (1) at 75°C to adjust the pH of the solution to 2.7, adjusting the pH for 5h, and adding 0.9 times the theoretical amount of iron powder required to replace nickel at 60°C, After the replacement, filter to obtain sponge nickel and nickel sinking mother liquor;

(3) adding hydrogen peroxide to the precipitation nickel mother liquor obtained in step (2), ferrous iron in the solution can be oxidized to ferric iron and then hydrolyzed to generate ferric hydroxide, filtered to obtain ferric hydroxide slag and precipitation iron mother liquor, and the ferronickel mother liquor returns Step (1) continues to dissolve nickel-iron alloy;

(4) adding 0.8mol/L sulfuric acid to the sponge nickel obtained in step (2) and dissolving, after filtration, obtain a crude product nickel sulfate solution;

(5) at 60 DEG C, the crude product nickel sulfate solution obtained in step (4), adding a sodium carbonate solution with a mass concentration of 25% to adjust pH to about 5, and filtering to obtain impurity removal slag and nickel sulfate solution;

(6) Evaporating and crystallizing the nickel sulfate solution obtained in step (5) at 85° C. for 6 hours to obtain battery-grade nickel sulfate crystals.

Get the nickel sulfate solution that above-mentioned embodiment 1～3 makes and carry out impurity content analysis, the result is as shown in following table 1:

Elemental analysis (%) of nickel sulfate crystals prepared in Table 1 Examples 1-3

	Ni	Fe	Co	Mn	Cu	Al
Example 1	22.274	0.0008	0.0162	0.0015	0.0009	0.0006
Example 2	22.258	0.0007	0.0121	0.0009	0.0005	0.0003
Example 3	22.219	0.0008	0.0174	0.0013	0.0007	0.0007
Example 4	22.235	0.0009	0.0169	0.0011	0.0009	0.0007

Example 5	22.261	0.0007	0.0155	0.0008	0.0008	0.0005
	Ca	Mg	Cd	Cr	Zn	Pb
Example 1	0.0025	0.0011	0.0001	0.0001	0.0001	0.0000
Example 2	0.0016	0.0009	0.0000	0.0000	0.0000	0.0000
Example 3	0.0027	0.0010	0.0002	0.0001	0.0001	0.0000
Example 4	0.0020	0.0012	0.0001	0.0001	0.0002	0.0000
Example 5	0.0013	0.0008	0.0001	0.0000	0.0001	0.0000

As can be seen from Table 1, the various impurity contents of the nickel sulfate crystal obtained by the preparation method of the present invention all meet the industry standard of battery grade nickel sulfate.

Get the iron hydroxide slag that above-mentioned embodiment 1～3 makes and carry out element content analysis, the result is as shown in following table 2:

Table 2 Elemental analysis (%) of iron hydroxide slag prepared in Examples 1-3

As can be seen from Table 2, the nickel content in the iron hydroxide slag prepared in Examples 1-5 of the present invention is relatively low, all below 0.4%, the loss of nickel is very small, and the content of other elements is lower, especially copper and aluminum If it is lower than 0.01, the iron hydroxide slag can be used in industries such as pigments, medicines and catalysts after further impurity removal and purification.

Comparative Example 1

The method for preparing nickel sulfate solution and battery-grade iron phosphate from nickel-containing pig iron of this comparative example includes the following steps:

(1) Raw material pretreatment, nickel-containing pig iron is dried and crushed into powder, and sieved for component detection;

(2) acid leaching treatment, using mixed acid to carry out normal pressure acid leaching on the undersize obtained in step (1), and obtaining filtrate after solid-liquid separation, the acid leaching temperature is 50～90 ℃, and the acid leaching time is 3～8 hours ;

(3) precipitation treatment, under the condition of using a precipitant to maintain the pH value of the filtrate in step (2), adding an oxidant simultaneously to oxidize the ferrous iron in the filtrate, adopting a controlled crystallization method to prepare iron phosphate precipitation, and filtering and washing after the reaction Then obtain nickel-containing filtrate and iron phosphate precipitation;

(4) Drying treatment of ferric phosphate, the solid ferric phosphate is vacuum-dried at 90-120 °C to obtain battery-grade anhydrous ferric phosphate products;

(5) nickel-containing filtrate extraction treatment, collecting the nickel-containing filtrate in step (3), using the diluted extractant to extract nickel, standing, and separating to obtain a nickel-containing extraction organic phase and an impurity-containing raffinate.

Table 3: Performance test results of nickel sulfate solution prepared in Comparative Example 1

Ingredient content (g/L)	Ni	Fe	Co	Mg	Ca	Cr
Comparative Example 1	23.21	0.00397	0.0017	0.0373	0.0241	0.0095

Table 3 shows the nickel sulfate solution obtained in Comparative Example 1, in which the concentrations of Mg, Ca, and Cr are relatively high. There will be high content of impurity ions, which do not meet the standard of battery-grade nickel sulfate.

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)

1. A method for separating nickel and iron from nickel-iron alloy, is characterized in that, comprises the steps:

   (1) nickel-iron alloy is dissolved in acid solution, filter, get filtrate, obtain acid nickel-iron solution;

   (2) pH is adjusted by the acid nickel-iron solution, heating, stirring, adding iron powder and continuing to heat and stir to obtain sponge nickel and precipitation nickel mother liquor;

   (3) carry out oxidizing and precipitating iron with described nickel-precipitating mother liquor, obtain ferric hydroxide slag and precipitating iron mother liquor;

   (4) dissolving the nickel sponge in sulfuric acid, filtering, collecting the filtrate, heating up, adjusting the pH, and obtaining a nickel sulfate solution.
2. The method according to claim 1, wherein in step (1), the acid solution is at least one of sulfuric acid or hydrochloric acid; ^and the concentration of H in the acid solution is 1-12 mol/L.
3. The method according to claim 1, wherein in step (1), the solid-to-liquid ratio of the nickel-iron alloy and the acid solution is 1: (1-100) g/mL.
4. The method according to claim 1, wherein, in step (2), the pH adjustment is to adjust the pH to 1.0-5.0, and the pH regulator used in the pH adjustment process is nickel-iron alloy, sodium hydroxide , at least one of sodium carbonate or ammonia water.
5. The method according to claim 1, characterized in that, in step (2), the amount of iron powder added is 0.5 to 5 times the theoretical amount required for nickel replacement.
6. The method according to claim 1, wherein, in step (3), the oxidant used in the process of oxidizing precipitation iron is at least one of hydrogen peroxide, oxygen, air, ozone or sodium persulfate.
7. The method according to claim 1, characterized in that, in step (3), the immersed iron mother liquor is an acidic solution containing ferric iron, and the immersed iron mother liquor returns to step (1) to continue circulating leaching, which can be mixed with nickel Iron in ferroalloys produces ferrous iron.
8. The method according to claim 1, characterized in that, in step (4), the concentration of the sulfuric acid is 0.1-10 mol/L; in step (4), the temperature for increasing the temperature is 30°C-90°C.
9. The method according to claim 1, characterized in that, after step (4), it further comprises the process of evaporating and crystallizing the nickel sulfate solution to obtain battery-grade nickel sulfate; The time is 1 ~ 20h.
10. Application of the method of any one of claims 1-9 in recycling non-ferrous metals.

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