Process for inhibiting silicon leaching during high-pressure leaching of laterite-nickel ore

Abstract

Disclosed in the present invention is a process for inhibiting silicon leaching during high-pressure leaching of laterite-nickel ore. The process comprises the following steps: performing first-stage high-pressure acid leaching on a laterite-nickel ore mixed ore slurry, and then performing second-stage medium-pressure acid leaching, the temperature of the first-stage high-pressure acid leaching being 230-260℃, and the temperature of the second-stage medium-pressure acid leaching being 150-200℃. In the present invention, high-pressure acid leaching is performed on laterite-nickel ore at a temperature of 230-260℃ to ensure that valuable metal nickel and cobalt can be effectively leached out while impurity metals such as iron and aluminum can be hydrolyzed as much as possible, and then second-stage medium-pressure acid leaching is performed at a temperature of 150-200℃ to promote hydrolysis of silicon to the maximum extent and greatly reduce the content of impurity silicon in the liquid obtained after leaching, thereby greatly reducing the content of silicon in subsequent MHP products, and further greatly improving the efficiency of an acid leaching procedure during the preparation of nickel sulfate crystals.

Description

A process for inhibiting silicon leaching during high-pressure leaching of laterite nickel ore Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and in particular relates to a process for inhibiting silicon leaching during high-pressure leaching of laterite nickel ore. Background Art

[0002] With the continuous decline in the grade and reserves of nickel sulfide ores, the preparation of nickel intermediates by laterite nickel ore leaching process has become one of the main sources of nickel resources for positive electrode materials of new energy ternary batteries.

[0003] Commonly used industrial hydrometallurgical processes for laterite nickel ore refining can be categorized as atmospheric pressure leaching and high-pressure leaching, depending on the pressure used during the leaching process. High-pressure leaching offers high nickel and cobalt recovery rates and strong selectivity. In recent years, international laterite nickel ore development projects have frequently employed the hydrometallurgical process of pressure acid leaching, garnering significant attention.

[0004] Due to the high silicate content in laterite nickel ore, the current high-pressure leaching process temperature of laterite nickel ore is generally between 230 and 260°C, resulting in a certain amount of silicon residue in the liquid after high-pressure leaching, which is further retained in the nickel intermediate MHP. In the subsequent process of MHP atmospheric pressure leaching to prepare nickel sulfate crystals, the silicate in the solution combines with hydrogen ions to transform into water-insoluble silicic acid precipitates. At the same time, the silicic acid mostly exists in the solution in the form of hydrogel, making filtration extremely difficult, which will seriously affect the production efficiency of nickel sulfate in production.

[0005] Summary of the Invention

[0006] In view of the shortcomings of the prior art, the object of the present invention is to provide a process for inhibiting silicon leaching during high-pressure leaching of laterite nickel ore, thereby solving the problem of silicon residue in the liquid after high-pressure leaching.

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

[0008] A process for inhibiting silicon leaching during high-pressure leaching of laterite nickel ore comprises the following steps: subjecting a mixed slurry of the laterite nickel ore to a first-stage high-pressure acid leaching and then to a second-stage medium-pressure acid leaching; the temperature of the first-stage high-pressure acid leaching is 230-260° C., and the temperature of the second-stage medium-pressure acid leaching is 150-200° C.

[0009] Preferably, the temperature of the second-stage medium-pressure acid leaching is 190°C.

[0010] Preferably, the leaching pressure of the first stage high-pressure acid leaching is 2.8-4.9 MPa.

[0011] Preferably, the leaching time of one stage of high pressure acid leaching is 0.5 to 2 hours.

[0012] Preferably, the pH value is controlled at 0.5-1.0 during the high pressure acid leaching process.

[0013] Preferably, the leaching pressure of the second-stage medium-pressure acid leaching is 1.5-1.8 MPa.

[0014] Preferably, the leaching time of the second-stage medium-pressure acid leaching is 0.5-3 hours.

[0015] Preferably, before the second stage medium pressure acid leaching, the ore pulp after the first stage high pressure acid leaching is flashed.

[0016] Preferably, the flash evaporation is a single-stage flash evaporation or a multi-stage flash evaporation, and the temperature is lowered to 150-200°C.

[0017] Preferably, the solid weight concentration of the laterite nickel ore mixed slurry is 30% to 40%.

[0018] The beneficial effects of the present invention are:

[0019] The present invention performs high-pressure acid leaching on laterite nickel ore at a temperature of 230-260°C to ensure that valuable metals nickel and cobalt can be effectively leached, while impurity metals such as iron and aluminum can be hydrolyzed as much as possible. Subsequently, a second-stage medium-pressure acid leaching is performed at a temperature of 150-200°C to maximize the hydrolysis of silicon. The impurity silicon content in the leached liquid is significantly reduced after leaching, thereby significantly reducing the silicon content in the subsequent MHP product, thereby significantly improving the efficiency of the acid leaching process in the preparation of nickel sulfate crystals. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] 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.

[0021] FIG1 is a process flow chart of the present invention for inhibiting silicon leaching during high-pressure leaching of laterite nickel ore. DETAILED DESCRIPTION

[0022] 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.

[0023] Referring to FIG1 , the process for inhibiting silicon leaching during high-pressure leaching of laterite nickel ore provided by the present invention comprises the following steps:

[0024] S1. Subject the mixed laterite nickel ore slurry to a high-pressure acid leaching process at a temperature of 230-260°C, a pH of 0.5-1.0, a leaching pressure of 2.8-4.9 MPa, and a leaching time of 0.5-2 hours. This ensures that the valuable metals nickel and cobalt are effectively leached, while impurity metals such as iron and aluminum are hydrolyzed as much as possible to reduce the iron and aluminum leaching rate.

[0025] S2. Flash evaporate the pulp after the first stage high-pressure leaching and cool it to 150-200°C. Then, it enters the second stage high-pressure leaching tank, where the temperature is controlled at 150-200°C, the leaching time is 0.5-3h, and the leaching pressure is 1.5-1.8Mpa to maximize the hydrolysis of silicon.

[0026] 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.

[0027] The composition of the laterite nickel ore used in the following examples is: Ni 1.18%, Co 0.109%, Fe 42.98%, Al 3.4%, Mg 1.4%, and Si 8.63%.

[0028] Example 1

[0029] Laterite nickel ore undergoes washing, screening (to remove particles and lumps ≥3mm), grinding, magnetic separation to remove chromium concentrate, and cyclone to finally obtain a slurry with a 200-mesh screening rate ≥95%. The slurry is then thickened to a 38% slurry concentration in a thickener and enters the high-pressure leaching process.

[0030] The mixed slurry of laterite nickel ore was pumped into an autoclave, concentrated sulfuric acid was added and the pH value during the leaching process was controlled at 1.0, the leaching pressure was 3.3 MPa, the leaching was carried out for 1 hour, and the first-stage leaching was carried out at 230°C. The temperature was lowered for solid-liquid separation. The nickel leaching rate was 95.5%, the cobalt leaching rate was 95.4%, and the silicon content in the first-stage leachate was 491 mg / L.

[0031] The first-stage leachate was flashed, cooled to 150°C, and then entered the second-stage high-pressure leaching tank. The temperature was maintained at 150°C and the pressure was 1.5 MPa for 30 minutes. The temperature was then lowered for solid-liquid separation. The silicon content in the second-stage leachate was 128 mg / L. The second-stage leachate was then used to prepare the MHP product according to conventional processes, with a silicon content of 0.073%.

[0032] Example 2

[0033] The laterite nickel ore slurry used is the same as that in Example 1.

[0034] The mixed slurry of laterite nickel ore was pumped into an autoclave, concentrated sulfuric acid was added and the pH value during the leaching process was controlled at 1.0, the leaching pressure was 3.8 MPa, the leaching was carried out for 1 hour, and the first-stage leaching was carried out at 240°C. The temperature was lowered for solid-liquid separation. The nickel leaching rate was 95.8%, the cobalt leaching rate was 95.9%, and the silicon content in the first-stage leaching solution was 503 mg / L.

[0035] The first-stage leachate was flashed, cooled to 160°C, and then entered the second-stage high-pressure leach tank. The temperature was maintained at 160°C and the pressure was 1.5 MPa for 30 minutes. The leachate was then cooled for solid-liquid separation. The silicon content in the second-stage leachate was 121 mg / L. The second-stage leachate was then used to prepare an MHP product using conventional processes, with a silicon content of 0.069%.

[0036] Example 3

[0037] The laterite nickel ore slurry used is the same as that in Example 1.

[0038] The mixed slurry of laterite nickel ore was pumped into an autoclave, concentrated sulfuric acid was added and the pH value during the leaching process was controlled at 1.0, the leaching pressure was 4.5 MPa, the leaching was carried out for 1 hour, and the first-stage leaching was carried out at 255°C. The temperature was lowered for solid-liquid separation. The nickel leaching rate was 96.3%, the cobalt leaching rate was 96.5%, and the silicon content in the first-stage leaching solution was 532 mg / L.

[0039] The first-stage leachate was flashed, cooled to 170°C, and then entered the second-stage high-pressure leaching tank. The temperature was maintained at 170°C and the pressure was 1.6 MPa for 30 minutes. The temperature was then lowered for solid-liquid separation. The silicon content in the second-stage leachate was 115 mg / L. The second-stage leachate was then used to prepare the MHP product according to conventional processes, with a silicon content of 0.061%.

[0040] Example 4

[0041] The laterite nickel ore slurry used is the same as that in Example 1.

[0042] The mixed slurry of laterite nickel ore was pumped into an autoclave, concentrated sulfuric acid was added and the pH value during the leaching process was controlled at 1.0, the leaching pressure was 4.9 MPa, the leaching was carried out for 1 hour, and the first-stage leaching was carried out at 260°C. The temperature was lowered for solid-liquid separation. The nickel leaching rate was 96.5%, the cobalt leaching rate was 96.8%, and the silicon content in the first-stage leachate was 541 mg / L.

[0043] The first-stage leachate was flashed, cooled to 180°C, and then entered the second-stage high-pressure leach tank. The temperature was maintained at 180°C and the pressure was 1.6 MPa for 30 minutes. The leachate was then cooled for solid-liquid separation. The silicon content in the second-stage leachate was 118 mg / L. The second-stage leachate was then used to prepare an MHP product using conventional processes, with a silicon content of 0.063%.

[0044] Example 5

[0045] The laterite nickel ore slurry used is the same as that in Example 1.

[0046] The mixed slurry of laterite nickel ore was pumped into an autoclave, concentrated sulfuric acid was added and the pH value during the leaching process was controlled at 1.0, the leaching pressure was 4.5 MPa, the leaching was carried out for 1 hour, and the first stage leaching was carried out at 255°C. The temperature was lowered for solid-liquid separation. The nickel leaching rate was 96.3%, the cobalt leaching rate was 96.5%, and the silicon content in the first stage leachate was 532 mg / L.

[0047] The first-stage leachate was flashed, cooled to 190°C, and then entered the second-stage high-pressure leach tank. The temperature was maintained at 190°C and the pressure was 1.7 MPa for 30 minutes. The leachate was then cooled for solid-liquid separation. The silicon content in the second-stage leachate was 110 mg / L. The second-stage leachate was then used to prepare an MHP product using conventional processes, with a silicon content of 0.056%.

[0048] Example 6

[0049] The laterite nickel ore slurry used is the same as that in Example 1.

[0050] The mixed slurry of laterite nickel ore was pumped into an autoclave, concentrated sulfuric acid was added and the pH value during the leaching process was controlled at 1.0, the leaching pressure was 4.5 MPa, the leaching was carried out for 1 hour, and the first-stage leaching was carried out at 255°C. The temperature was lowered for solid-liquid separation. The nickel leaching rate was 96.3%, the cobalt leaching rate was 96.5%, and the silicon content in the first-stage leaching solution was 532 mg / L.

[0051] The first-stage leachate was flashed, cooled to 200°C, and then entered the second-stage high-pressure leaching tank. The temperature was controlled at 200°C and the pressure was 1.8 MPa. The leaching time was 30 minutes. The temperature was then lowered for solid-liquid separation. The silicon content in the second-stage leachate was 116 mg / L. The second-stage leachate was then used to prepare the MHP product according to conventional processes. The silicon content in the product was 0.062%.

[0052] Comparative Example 1

[0053] The laterite nickel ore slurry used was the same as in Example 1. The mixed laterite nickel ore slurry was pumped into an autoclave and subjected to high-pressure acid leaching with concentrated sulfuric acid. The leaching temperature was set at 255°C and the leaching pressure was set at 4.5 MPa for 1.5 hours. The temperature was then lowered for solid-liquid separation. The measured nickel leaching yield was 96.1%, the cobalt leaching yield was 96.4%, and the Si content in the leachate was 530 mg / L. The Si content of the final MHP product was 0.186%.

[0054] In summary, the present invention significantly reduces the silicon content in the laterite nickel ore leachate by performing two-stage leaching on the laterite nickel ore and rationally controlling the leaching temperature of the two-stage leaching, thereby significantly reducing the silicon content in the subsequent MHP product, thereby improving the efficiency of the acid leaching process in the preparation of nickel sulfate crystals.

[0055] 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.

[0056] 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 process for suppressing silicon leaching during the high-pressure leaching of laterite nickel ore, characterized in that, it comprises the following steps: Performing first-stage high-pressure acid leaching on the laterite nickel ore mixed pulp, and then performing second-stage medium-pressure acid leaching; the temperature of the first-stage high-pressure acid leaching is 230 - 260 °C, and the temperature of the second-stage medium-pressure acid leaching is 150 - 200 °C.

2. The process for suppressing silicon leaching during the high-pressure leaching of laterite nickel ore according to claim 1, characterized in that, the temperature of the second-stage medium-pressure acid leaching is 190 °C.

3. The process for suppressing silicon leaching during the high-pressure leaching of laterite nickel ore according to claim 1, characterized in that, the leaching pressure of the first-stage high-pressure acid leaching is 2.8 - 4.9 Mpa.

4. The process for suppressing silicon leaching during the high-pressure leaching of laterite nickel ore according to claim 1, characterized in that, the leaching time of the first-stage high-pressure acid leaching is 0.5 - 2 h.

5. The process for suppressing silicon leaching during the high-pressure leaching of laterite nickel ore according to claim 1, characterized in that, the pH during the first-stage high-pressure acid leaching is controlled at 0.5 - 1.

0.

6. The process for suppressing silicon leaching during the high-pressure leaching of laterite nickel ore according to claim 1, characterized in that, the leaching pressure of the second-stage medium-pressure acid leaching is 1.5 - 1.8 Mpa.

7. The process for suppressing silicon leaching during the high-pressure leaching of laterite nickel ore according to claim 1, characterized in that, the leaching time of the second-stage medium-pressure acid leaching is 0.5 - 3 h.

8. The process for suppressing silicon leaching during the high-pressure leaching of laterite nickel ore according to claim 1, characterized in that, before the second-stage medium-pressure acid leaching, it further includes flash evaporation of the pulp after the first-stage high-pressure acid leaching.

9. The process for suppressing silicon leaching during the high-pressure leaching of laterite nickel ore according to claim 8, characterized in that, the flash evaporation is single-stage flash evaporation or multi-stage flash evaporation, and the temperature is reduced to 150 - 200 °C.

10. The process for suppressing silicon leaching during the high-pressure leaching of laterite nickel ore according to claim 1, characterized in that, the solid weight concentration of the laterite nickel ore mixed pulp is 30% - 40%.

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