Method for producing nickel sulfate solution from low-nickel high-impurity nickel raw material

Abstract

The invention discloses a method for producing a nickel sulfate solution from a low-nickel high-impurity-nickel raw material, the method comprises the procedures of burdening, normal-pressure leaching, pressure leaching, two-stage pressure leaching and the like, a new kettle is added for pressure leaching, an oxygen introducing mode, a stirring device, a discharging system and the like are included, selective leaching of nickel is achieved, and the high-nickel low-iron low-copper nickel sulfate solution is obtained. The nickel leaching rate index of the solution reaches 93%; the finished nickel sulfate product contains more than or equal to 100g / L of nickel, less than or equal to 3g / L of copper and less than or equal to 1g / L of iron and meets the quality of the nickel sulfate solution for the battery; and copper, iron and precious metal are enriched in the second-stage pressure leaching tailings for external pyrogenic process treatment. The method has the advantages that the nickel leaching rate is high, and the content of copper and iron impurities in the nickel sulfate solution is low.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and in particular to a method for producing a nickel sulfate solution from a low-nickel and high-impurity nickel raw material. Background Art

[0002] Nickel sulfate is mainly used in the surface treatment industry and the power battery industry. It is the main nickel salt for electroplating nickel and chemical nickel plating, and is the main raw material for manufacturing power batteries. With the continuous excavation of nickel ore, the raw materials purchased by the production line for producing nickel sulfate are low-nickel and high-impurity raw materials. At present, the production of nickel sulfate from low-nickel and high-impurity nickel raw materials adopts normal pressure leaching and pressure leaching processes, which cannot achieve selective leaching of nickel. In addition, due to the low copper content and high proportion of alloy phase, hydrogen sulfide gas is easily generated and the solution delivery pipeline, valves, and pump facilities are blocked. Therefore, it is urgently required to further study and improve the method of preparing nickel sulfate solution from low-nickel and high-impurity materials in order to produce nickel sulfate solution for batteries. Summary of the invention

[0003] The object of the present invention is to provide a method for producing nickel sulfate solution from a low-nickel and high-impurity nickel raw material to solve the problems raised in the above background technology.

[0004] The present invention adopts the following technical solution: A method for producing a nickel sulfate solution from a low-nickel and high-impurity nickel raw material comprises the following steps: 1) One-stage normal pressure slurry batching stage: low-nickel high-impurity nickel raw material and self-produced nickel concentrate are mixed to obtain mixed raw material, the nickel content of the mixed raw material is controlled at more than 62%, to ensure the improvement of nickel leaching rate and inhibit the formation of iron, the mixed raw material and the first-stage pressurized leaching liquid are slurried to prepare a first-stage normal pressure slurry slurry with a concentration of 25%~35%; the chemical composition of the low-nickel high-impurity nickel raw material is: nickel 52~57%, copper ≤1%, iron 2~4%, cobalt 1~3%, and the chemical composition of the self-produced nickel concentrate is: nickel 64~70%, copper 3~6%, iron 2~5%, cobalt ≤3%.

[0005] 2) Normal pressure leaching stage: the first stage of normal pressure pulping slurry is subjected to the first stage of normal pressure leaching and the second stage of normal pressure leaching, the temperature of the first stage of normal pressure leaching is 70~90℃, and the pH of the leaching end point is 4.5~6.0; after the first stage of normal pressure leaching, the supernatant and the underflow are obtained after concentration and separation by a thickener; the supernatant after the first stage of normal pressure leaching is filtered by a filter press to obtain a finished nickel sulfate solution, the nickel sulfate solution contains ≥100g / L of nickel, ≤3g / L of copper, and ≤1g / L of iron; the first stage of normal pressure leaching uses a pressurized leaching liquid for pulping, and the leaching process precipitates copper and iron in the solution to obtain a finished nickel sulfate solution for batteries with copper and iron meeting the product quality requirements.

[0006] The second-stage pressure leaching solution and sulfuric acid are added to the bottom flow after the first-stage atmospheric pressure leaching concentration separation to prepare a second-stage atmospheric pressure slurry solution with a liquid-solid ratio of 7-11:1 and a pH of 0.5-1.0 for the second-stage atmospheric pressure leaching. The second-stage atmospheric pressure leaching temperature is 70-90°C, and the pH value at the leaching end point is 2.5-3.5; 3) Pressure leaching stage: The slurry of the second stage atmospheric leaching is subjected to the first stage pressure leaching and the second stage pressure leaching in the pressure autoclave; the temperature of the first stage pressure leaching is controlled at 140~180℃, the autoclave pressure is controlled at 0.55~0.85MPa, and the oxygen partial pressure is controlled at 0.15~0.50MPa for 4~6 hours; the slurry of the first stage pressure leaching is sent to the thickener for concentration and separation after cooling and pressure reduction to obtain the supernatant and the underflow, and the supernatant is filtered through the filter press to obtain the first stage pressure leaching The liquid is returned to the first normal pressure slurry batching stage for slurry batching, sulfuric acid and water are added to the thickener bottom flow for second stage pressure leaching, the second stage pressure leaching temperature is controlled at 100-180°C, the kettle pressure is at 0.3-0.8MPa, and the oxygen partial pressure is at 0.10-0.50MPa for 4-6 hours. The second stage pressure leaching slurry is cooled and decompressed, filtered to obtain the second stage pressure leaching liquid and the second stage pressure leaching tailings, and the second stage pressure leaching liquid is sent to the second stage normal pressure batching.

[0007] The composition of the first stage pressurized leaching solution is nickel 100~140g / L, copper ≤30g / L, iron ≤5g / L In the pressurized stage, metal sulfides are dissolved in an oxidizing atmosphere. The leaching conditions are controlled to selectively leach Cu, and most of the precious metals enter the final pressurized leaching residue; Oxygen supply method for pressure autoclave: The pressure autoclave adopts bottom oxygen supply to avoid pipe bending affecting the oxygen flow rate; high-pressure air is used to clear the oxygen pipeline, and the compressed air entering the autoclave can participate in the reaction without affecting the leaching effect.

[0008] In the present invention, in addition to the nickel sulfate solution, the second-stage pressure leaching liquid is separated by a filter press to obtain the second-stage pressure leaching residue, which is sent to the pyrometallurgical system for recovery.

[0009] In summary, this method uses high-nickel and high-copper materials, adds appropriate sulfuric acid and oxygen, adds a two-stage pressurized leaching process, controls the kettle temperature, kettle pressure and pH value, solves the problem that the raw materials with low nickel, low copper and high iron cannot achieve selective leaching of nickel, and eliminates the generation of hydrogen sulfide gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0011] The present invention will be further described below through specific implementation modes.

[0012] like Figure 1As shown, a method for producing a nickel sulfate solution from a low-nickel and high-impurity nickel raw material comprises the following steps: (1) Batching stage: Take a low-nickel, high-impurity raw material with a typical composition of 55.48% nickel, 0.018% copper, 3.23% iron and 1.37% cobalt, and mix it with self-produced nickel concentrate. The chemical composition of the mixed raw material is 63.35% nickel, 3.751% copper, 3.73% iron and 1.11% cobalt. The nickel grade of the mixed raw material is increased to 63.35%. The mixed raw material is mixed with the first-stage pressurized leaching liquid returned from the pressurization stage to prepare a first-stage atmospheric pressure pulping slurry with a concentration of 30%; (2) Normal pressure leaching stage: The normal pressure pulping slurry is sent to the normal pressure reaction tank for normal pressure leaching. The temperature of the reaction tank is 70~90℃, the pH of the first leaching end point is 4.5~6.0, and compressed air of 1200Nm is introduced. 3 / (h. tank), after leaching, send it to a thickener for concentration and separation to obtain a supernatant and an underflow, and then filter the supernatant through a filter press to obtain a nickel sulfate solution; the nickel sulfate solution contains nickel ≥100g / L, copper ≤3g / L, and iron ≤1g / L. The specific ingredients are: nickel 110.96g / L; copper 3.3g / L; iron 0.3g / L; cobalt 1.53g / L; lead 0.001g / L; zinc 0.32g / L; sodium 0.066g / L; pH 5.0~5.5.

[0013] The bottom flow after the first stage of atmospheric pressure leaching is added to the second stage of pressurized leaching liquid to form a second stage atmospheric pressure slurry with a liquid-solid ratio of 7-11:1 and a pH of 0.5-1.0. The second stage atmospheric pressure slurry contains copper: 0.5-3g / L, and is sent to the atmospheric pressure reaction tank for atmospheric pressure leaching. The temperature of the reaction tank is 70-90℃. The pH value of the second stage leaching end point is 2.5-3.5. Compressed air is introduced at 1000Nm 3 / (h. tank), after leaching, send to pressure kettle for pressure leaching; (3) Pressure leaching stage: The slurry from the second stage of normal pressure leaching is subjected to pressure leaching. The temperature of the first stage of pressure leaching is controlled at 140-180°C, the kettle pressure is controlled at 0.55-0.85MPa, and the oxygen partial pressure is controlled at 0.15-0.50MPa for 5 hours. The composition of the first stage of pressure leaching liquid is 100-140g / L nickel, ≤30g / L copper, and ≤5g / L iron. The first stage of pressure leaching slurry is cooled and depressurized in a flash evaporator and then sent to a thickener for concentration and separation to obtain a supernatant and an underflow. The supernatant is then passed through a The first-stage pressurized leaching liquid is filtered through a filter press and pumped to a first-stage normal pressure slurry tank through a pipeline for slurrying and batching; sulfuric acid and water are added to the underflow for second-stage pressurized leaching, and the second-stage pressurized leaching temperature is controlled at 100-180°C, the kettle pressure is at 0.3-0.8MPa, and the oxygen partial pressure is at 0.10-0.50MPa. The reaction takes 5 hours. The second-stage pressurized leaching slurry is cooled and decompressed by a flash tank, and then transported to a diaphragm filter press through a pipeline for filtration. The filtrate is transported to the second-stage normal pressure batching, and the filter residue is externally supplied to the pyrometallurgical system.

[0014] Oxygen supply method for autoclave: adopt bottom oxygen supply, and the oxygen flow rate of autoclave is controlled to <400m 3 / h, usually 240~290m 3 / h, the slurry flow rate into the kettle is 7.5m 3 / h, the oxygen consumption per unit slurry flow is 32~38.7m 3 The oxygen supply method of the old pressure kettle is to enter from the top and discharge from the bottom of the slurry in the kettle. The slurry flow rate into the kettle is 6.3m 3 / h, oxygen flow rate of autoclave is 250m 3 / h, and the oxygen consumption per unit slurry flow is 39.5m 3 The bottom oxygen supply method is significantly better than the top oxygen supply method. The newly added high-pressure air dredges the oxygen pipeline, with high purging pressure, long duration, good purging effect, and the compressed air entering the kettle can participate in the reaction without affecting the leaching effect.

[0015] Stirring method of autoclave: The first three compartments of the autoclave adopt six straight blade disc turbine stirring, which belongs to runoff strong stirring and is suitable for high-capacity and high-concentration slurry; the last compartment adopts three-blade stirring, which is suitable for reducing the viscosity of four-compartment slurry after leaching.

[0016] Autoclave discharge: The autoclave discharge adopts the flash valve discharge method, and the discharge first enters the pre-flash tank (0.35MPa) and then enters the flash tank for step-by-step flashing. The flash tank adopts the side discharge method, and a sewage pipe is set at the bottom. The frequency of leakage in the discharge pipe is significantly reduced.

Claims

1. A method for producing nickel sulfate solution from a low-nickel and high-mix nickel raw material, characterized in that: The following steps are involved: 1) One-stage atmospheric pressure slurry batching: low-nickel high-impurity nickel raw material and nickel concentrate are proportioned to obtain a mixed raw material, the nickel content of the mixed raw material is controlled to be above 62%, to ensure the improvement of nickel leaching rate and inhibit the formation of iron, the mixed raw material and the first-stage pressurized leaching liquid are configured to form a first-stage atmospheric pressure slurry with a concentration of 25%~35%; 2) Normal pressure leaching stage: the first stage of normal pressure pulping slurry is subjected to the first stage of normal pressure leaching and the second stage of normal pressure leaching, the temperature of the first stage of normal pressure leaching is 70-90°C, and the pH of the leaching end point is 4.5-6.0; after the first stage of normal pressure leaching, the supernatant and the underflow are obtained after concentration and separation by a thickener; the supernatant after the first stage of normal pressure leaching is filtered by a filter press to obtain a finished nickel sulfate solution, the nickel sulfate solution contains ≥100g / L nickel, ≤3g / L copper, and ≤1g / L iron; The second-stage pressure leaching solution and sulfuric acid are added to the bottom flow after the first-stage atmospheric pressure leaching concentration separation to prepare a second-stage atmospheric pressure slurry solution with a liquid-solid ratio of 7-11:1 and a pH of 0.5-1.0 for the second-stage atmospheric pressure leaching. The second-stage atmospheric pressure leaching temperature is 70-90°C, and the pH value at the leaching end point is 2.5-3.5; 3) Pressure leaching stage: The two-stage normal pressure leaching pulp is subjected to the first-stage pressure leaching and the second-stage pressure leaching in the pressure autoclave; the first-stage pressure leaching temperature is controlled at 140~180℃, the autoclave pressure is controlled at 0.55~0.85MPa, and the oxygen partial pressure is controlled at 0.15~0.50MPa for 4~6 hours; the first-stage pressure leaching pulp is sent to the thickener for concentration and separation after cooling and pressure reduction to obtain the supernatant and the underflow, and the supernatant is filtered through the filter press to obtain the first-stage pressure leaching liquid, which is returned to the first-stage normal pressure slurry batching stage for slurrying The process comprises the following steps: batching, adding sulfuric acid and water to the underflow for two-stage pressure leaching, controlling the temperature of the two-stage pressure leaching at 100-180°C, the kettle pressure at 0.3-0.8MPa, and the oxygen partial pressure at 0.10-0.50MPa for 4-6 hours, cooling and decompressing the two-stage pressure leaching slurry, filtering, obtaining a two-stage pressure leaching liquid and a two-stage pressure leaching tailing, and sending the two-stage pressure leaching liquid to the two-stage normal pressure batching; in the pressurization stage, the nickel sulfide which is difficult to be leached under normal pressure is dissolved under an oxidizing atmosphere, thereby improving the leaching rate of nickel; The composition of the first-stage pressurized leaching solution is 100-140 g / L nickel, ≤30 g / L copper, and ≤5 g / L iron.

2. A method for producing nickel sulfate solution from a low-nickel and high-mix nickel raw material as claimed in claim 1, characterized in that: In step 1), the chemical composition of the low-nickel and high-impurity nickel raw material is: nickel 52-57%, copper ≤1%, iron 2-4%, cobalt 1-3%; the chemical composition of the nickel concentrate is: nickel 64-70%, copper 3-6%, iron 2-5%, cobalt ≤3%, and the first-stage normal pressure fore liquid contains nickel ≥70g / L; the mass ratio of the low-nickel and high-impurity nickel raw material to the nickel concentrate is 2.5-3.5:

1.

3. A method for producing nickel sulfate solution from a low-nickel and high-mix nickel raw material as claimed in claim 1, characterized in that: In step 3), the oxygen supply method of the autoclave is bottom oxygen supply, and high-pressure air is used to clear the oxygen supply pipeline.

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