Method for extracting metals from saprolite lateritic nickel ore

Abstract

A method for extracting metals from saprolite lateritic nickel ore, comprising: subjecting saprolite lateritic nickel ore to ore dressing and ore milling, so as to obtain lateritic nickel ore powder; mixing the lateritic nickel ore powder, water, an acid and a reducing agent and performing normal-pressure acid leaching, so as to obtain a leaching residue and a leachate; adding a soluble fluoride salt and sodium salt into the leachate so as to obtain a silicon-aluminum residue and a silicon and aluminum-removed liquid; adding a phosphorus source into the silicon and aluminum-removed liquid, and performing solid-liquid separation to obtain ferric phosphate and a post-iron-precipitation liquid; performing primary cyclone electrolysis on the post-iron-precipitation liquid, so as to obtain a zinc-chromium alloy and a post-primary-cyclone-electrolysis liquid; performing secondary cyclone electrolysis on the post-primary-cyclone-electrolysis liquid, so as to obtain a nickel-cobalt alloy, manganese oxide and a post-secondary-cyclone-electrolysis liquid; and adding sodium carbonate into the post-secondary-cyclone-electrolysis liquid to perform a precipitation reaction, so as to obtain magnesium carbonate and a post-magnesium-precipitation liquid. The method achieves short-process separation and extraction of different valuable metal elements such as zinc, chromium, nickel, cobalt and manganese from saprolite lateritic nickel ore, and is an economical, efficient, green and environment-friendly extraction technique.

Description

A method for extracting metal from saprolitic laterite nickel ore Technical Field

[0001] The invention belongs to the technical field of laterite nickel ore hydrometallurgy, and in particular relates to a method for extracting metal from saprolite-type laterite nickel ore. Background Art

[0002] With the rapid development of new energy, ternary lithium batteries are a crucial component of the future new energy sector. As nickel is a key component of ternary lithium batteries, efficient nickel resource extraction technology has become crucial for the entire new energy industry. Laterite nickel ore is one of the main forms of nickel in nature, with enormous reserves.

[0003] Current processing methods for laterite nickel ore include pyrometallurgy and hydrometallurgy. For laterite nickel ore with a nickel grade below 1.3%, the basic process is based on hydrometallurgy, which includes mineral pretreatment, high-pressure leaching, neutralization and impurity removal, nickel-cobalt hydroxide precipitation (MHP), acid dissolution, extraction and crystallization, and ultimately, various nickel-cobalt products. Low-grade saprolite-type laterite nickel ore contains significant amounts of elements such as iron and magnesium. During these processes, iron is discarded as slag, and magnesium is discharged as entrained elements in wastewater, resulting in significant waste of resources.

[0004] At present, the process research for low-grade laterite nickel ore is based on the use of nickel and cobalt in the mineral as the basic starting point, but other valuable metals therein are not reasonably utilized. There are also reports that the iron concentrate is recovered by reducing roasting-magnetic separation of laterite nickel ore smelting slag, but due to the low added value of iron, it is often not economically beneficial. For example, patent No. CN 103526046 A discloses an additive for the reduction of humus-type laterite nickel ore and its application, which is obtained by adding an additive to the humus-type laterite nickel ore, crushing and grinding the ore after reduction to obtain a powder, and then obtaining a nickel-iron alloy by magnetic separation. Therefore, it is necessary to develop a method for extracting multiple valuable metals from saprolite-type laterite nickel ore.

[0005] Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for extracting metals from saprolitic laterite nickel ore. This method combines wet processing with electrochemical metallurgy to extract and recover elements such as iron and magnesium during the laterite nickel ore processing phase. This allows for a short-term, deep separation of different metal elements, improving the utilization rate of valuable metals in the laterite nickel ore.

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

[0008] A method for extracting metal from saprolitic laterite nickel ore comprises the following steps:

[0009] (1) beneficiating and grinding the saprolite-type laterite nickel ore to obtain laterite nickel ore powder;

[0010] (2) mixing laterite nickel ore powder, water, acid and a reducing agent to prepare a slurry, and then performing normal pressure acid leaching to obtain leaching residue and leachate;

[0011] (3) adding a soluble fluoride salt and a soluble sodium salt to the leachate to obtain a silicoaluminate slag and a silicoaluminate-free solution; the silicoaluminate slag contains sodium fluoroaluminate and sodium fluorosilicate;

[0012] (4) adding a phosphorus source to the liquid after silicon and aluminum removal, and performing solid-liquid separation to obtain iron phosphate and iron precipitation liquid;

[0013] (5) performing one-step cyclone electrolysis on the iron precipitation liquid to obtain a zinc-chromium alloy and a one-step cyclone electrolysis liquid;

[0014] (6) performing a second-step cyclone electrolysis on the liquid after the first-step cyclone electrolysis to obtain a nickel-cobalt alloy, manganese oxide, and a second-step cyclone electrolysis liquid;

[0015] (7) Sodium carbonate is added to the liquid after the second-step cyclonic electrolysis to carry out a precipitation reaction to obtain magnesium carbonate and magnesium precipitation liquid.

[0016] Preferably, the acid in step (2) is an organic acid or an inorganic acid, and the reducing agent is one or more of sodium sulfite, sodium bisulfite, sodium metabisulfite, iron powder, and ferrous sulfate.

[0017] Preferably, the concentration of the acid in step (2) is 1-3 mol / L, the amount of the reducing agent is 5-20 g / L, and the solid-liquid ratio of the slurry is 50-300 g / L.

[0018] Preferably, the leaching temperature of the normal pressure acid leaching in step (2) is 50-90° C., and the leaching time is 1-5 h.

[0019] Preferably, in step (3), the soluble fluoride salt is at least one of sodium fluoride, potassium fluoride, and ammonium fluoride; and the soluble sodium salt is at least one of sodium fluoride, sodium chloride, and sodium sulfate.

[0020] Preferably, in step (3), the amount of soluble fluoride salt used is 3-20 g / L, and the amount of soluble sodium salt used is 5-20 g / L; and the pH of the leachate is controlled to 1-3 using dilute alkali solution, and the reaction is carried out at room temperature for 0.5-3 hours.

[0021] Preferably, the phosphorus source in step (4) is one or more of phosphoric acid, sodium phosphate, ammonium dihydrogen phosphate, ammonium monohydrogen phosphate, and ammonium phosphate; and the molar ratio of the phosphorus source to the iron element in the leachate is (1-1.1):1.

[0022] Preferably, in the one-step cyclone electrolysis of step (5), the acidity of the solution after iron precipitation is 0.1-0.3 mol / L, the temperature is 30-40°C, and the current density is 400-600 A / m 2 , the electrolysis time is 5-10h.

[0023] Preferably, in the second-step cyclone electrolysis of step (6): the pH of the solution after the first-step cyclone electrolysis is controlled to be 2-4, the temperature to be 40-50°C, and the current density to be 100-200A / m 2 , the electrolysis time is 5-10h.

[0024] Preferably, the above method further comprises evaporating and concentrating the liquid after magnesium precipitation to obtain sodium sulfate, and reusing the sodium sulfate as sodium salt for silicon and aluminum removal in step (3).

[0025] The beneficial effects of the present invention are:

[0026] In response to the current situation of low resource recovery and utilization rate in saprolite-type laterite nickel ore, the present invention proposes a method for extracting metals from saprolite-type laterite nickel ore. The method realizes short-process deep separation and extraction of different valuable metal elements such as zinc, chromium, nickel, cobalt and manganese in saprolite-type laterite nickel ore through the steps of normal pressure acid leaching-silicon and aluminum removal-ferric phosphate precipitation-one-step cyclone electrolysis-two-step cyclone electrolysis-magnesium carbonate precipitation, and is an economical, efficient, green and environmentally friendly extraction process.

[0027] The present invention evaporates and concentrates the filtrate after magnesium extraction, crystallizes and precipitates sodium sulfate, and reuses the sodium sulfate in the silicon and aluminum removal step, thereby greatly reducing production costs and achieving a high degree of resource utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] 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.

[0029] FIG1 is a flow chart of a method for extracting metal from saprolite-type laterite nickel ore according to the present invention;

[0030] FIG2 is a SEM image of the iron phosphate prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0031] 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.

[0032] Referring to FIG1 , the method for extracting metal from saprolitic laterite nickel ore provided by the present invention comprises the following steps:

[0033] (1) beneficiating and grinding the saprolite-type laterite nickel ore to obtain laterite nickel ore powder;

[0034] (2) mixing laterite nickel ore powder, water, acid and reducing agent to prepare slurry, and then acid leaching at normal pressure at a temperature of 50-90°C for 1-5 hours to obtain leaching residue and leachate; wherein the acid concentration is 1-3 mol / L, the amount of reducing agent is 5-20 g / L, and the solid-liquid ratio of the slurry is 50-300 g / L.

[0035] The acid used in the atmospheric pressure acid leaching of the present invention is an organic acid or an inorganic acid commonly used in the art. For example, the inorganic acid can be one or more of sulfuric acid, phosphoric acid, nitric acid, and hydrochloric acid; the organic acid can be one or more of formic acid, oxalic acid, citric acid, acetic acid, and ascorbic acid; the reducing agent can be one or more of sodium sulfite, sodium bisulfite, sodium metabisulfite, iron powder, and ferrous sulfate.

[0036] (3) adding any one or more soluble fluoride salts such as sodium fluoride, potassium fluoride, ammonium fluoride, and soluble sodium salts such as sodium chloride, sodium fluoride, and sodium sulfate to the leachate, wherein the amount of the soluble fluoride salt is 3-20 g / L, and the amount of the soluble sodium salt is 5-20 g / L; and controlling the pH of the leachate to 1-3 with a dilute alkali solution, reacting at room temperature for 0.5-3 hours, so that aluminum precipitates in the form of cryolite and silicon precipitates in the form of sodium fluorosilicate, and obtaining silicon-aluminum slag and a liquid after removing silicon and aluminum after solid-liquid separation;

[0037] (4) adding a phosphorus source to the liquid after silicon and aluminum removal to carry out precipitation reaction, wherein the phosphorus source can be one or more of phosphoric acid, sodium phosphate, ammonium dihydrogen phosphate, ammonium monohydrogen phosphate, and ammonium phosphate, preferably sodium phosphate, and the molar ratio of the phosphorus source to the iron element in the leachate is (1-1.1):1, and after solid-liquid separation, iron phosphate and iron precipitation liquid are obtained;

[0038] The precipitation method for preparing ferric phosphate according to the present invention preferably adopts a "two-step process", that is, first precipitating to prepare crude ferric phosphate and then transforming and aging to prepare battery-grade ferric phosphate. The entire process parameters are controlled as follows: first, dilute sulfuric acid or dilute alkali solution is used to control the pH of the solution after silicon and aluminum removal to 1.8-2.0, and the phosphorus source and the iron in the solution are reacted at a temperature of 55-60°C for 2 hours. Then, the phosphorus source is added to the solution in an amount of 0.1 mol / L, the temperature is controlled at 85-90°C, the reaction is continued for 2 hours, and the battery-grade ferric phosphate is obtained by filtration and washing.

[0039] (5) performing one-step cyclone electrolysis on the iron precipitation solution to obtain a zinc-chromium alloy and a one-step cyclone electrolysis solution; wherein the conditions for the one-step cyclone electrolysis are: solution acidity 0.1-0.3 mol / L, temperature 30-40°C, current density 400-600 A / m 2The electrolysis time is 5-10h, the cathode is a crude zinc plate, and the anode is a lead-silver alloy plate. During the electrolysis process, zinc-chromium alloy is deposited on the cathode plate, and the cathode plate replacement cycle is 48h.

[0040] According to the present invention, after the one-step cyclone electrolysis, the zinc-chromium alloy deposited on the cathode plate can be further electrolytically refined by current means in the industry to obtain high-purity zinc.

[0041] (6) performing a second-step cyclone electrolysis on the liquid after the first-step cyclone electrolysis to obtain nickel-cobalt alloy, manganese oxide and the liquid after the second-step cyclone electrolysis; the conditions for the second-step cyclone electrolysis are: controlling the pH of the liquid after the first-step cyclone electrolysis to be 2-4, the temperature to be 40-50°C, and the current density to be 100-200A / m 2 The electrolysis time is 5-10h, the cathode is a stainless steel plate, the anode is a lead-silver alloy plate, and a diaphragm bag is placed. The Ni-Co alloy formed by cathode electrodeposition has a stripping cycle of 48h to obtain Ni-Co alloy, and MnO2 is collected in the anode diaphragm bag.

[0042] (7) Sodium carbonate was added to the solution after the second-step cyclone electrolysis to adjust the pH of the solution to 10-12, and the precipitation reaction was carried out at room temperature for 0.5 h. After solid-liquid separation, magnesium carbonate and magnesium precipitation solution were obtained.

[0043] (8) The solution after magnesium precipitation is evaporated and concentrated, and crystallized to obtain sodium sulfate, which is then reused as sodium salt for the silicon-aluminum removal in step (3).

[0044] 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.

[0045] The components of the saprolite-type laterite nickel ore used in the following examples are shown in Table 1:

[0046] Table 1 Composition of saprolitic laterite nickel ore

[0047] Example 1

[0048] A method for extracting metal from saprolitic laterite nickel ore comprises the following steps:

[0049] Saprolitic laterite nickel ore is beneficiated and ground to produce laterite nickel ore powder. The laterite nickel ore powder is then mixed with water, sulfuric acid, and sodium metabisulfite at a solid-to-liquid ratio of 200 g / L to produce a slurry containing 2 mol / L sulfuric acid and 10 g / L sodium metabisulfite. The slurry is heated to 80°C and stirred for 2 hours. After completion of the reaction, the leaching residue and leachate are filtered and obtained. The contents of metals such as Ni, Co, Mn, and Fe in the leaching residue are measured to be less than 0.05%, and the residual acid in the leachate is approximately 0.3 mol / L. The leached residue can be used as a brickmaking material or directly landfilled.

[0050] 10 g / L of NaF and 10 g / L of Na2SO4 were added to the leachate, and the pH was adjusted to 2 with a 10% NaOH solution. After reacting for 1 hour, the solution was filtered to obtain silicon-aluminum slag and a silicon-aluminum-free solution. The concentrations of residual aluminum and silicon in the silicon-aluminum-free solution were measured to be below 5 ppm. Sodium phosphate was further added to the silicon-aluminum-free solution to adjust the molar ratio P / Fe in the solution to 1.05. The "two-step method" was used for iron precipitation, and iron phosphate and a solution after iron precipitation were obtained by filtration. The Fe / P molar ratio in the iron phosphate was measured to be 0.975, and the content of impurity elements met the requirements of the battery-grade iron phosphate industry standard (HG / T4701-2021). The SEM image of the iron phosphate is shown in Figure 2.

[0051] The two-step cyclone electrolysis method is used to recover valuable metals from the iron precipitation liquid. The process parameters of the one-step cyclone electrolysis are as follows: the acidity of the iron precipitation liquid is controlled to be 0.2 mol / L, the solution temperature is 35 ° C, and the current density is 500 A / m 2 The electrolysis time is 8h, the cathode is a crude zinc plate, the anode is a lead-silver alloy plate, and zinc-chromium alloy is deposited on the cathode plate during the electrolysis process. The cathode plate replacement cycle is 48h. After the electrolysis is completed, the Zn content in the solution is measured. 2+ The concentration of Cr 3+ The concentration of Ni 2+ 、Co 2+ 、Mn 2+ The loss rate is below 1%. Then, the solution after the first-step cyclone electrolysis is subjected to a second-step cyclone electrolysis to obtain nickel-cobalt alloy, manganese oxide and the solution after the second-step cyclone electrolysis. The process parameters of the second-step cyclone electrolysis are as follows: adjust the solution pH to 3, the solution temperature to 50°C, and the current density to 150A / m 2 The electrolysis time is 8h, the cathode is a stainless steel plate, the anode is a lead-silver alloy plate, and a diaphragm bag is used. The Ni-Co alloy formed by cathode electrodeposition is stripped off in a cycle of 48h to obtain Ni-Co alloy, and MnO2 is collected in the anode diaphragm bag. After the electrolysis is completed, Ni in the solution 2+ 、Co 2+ The ion concentration dropped to below 50ppm, Mn 2+ The ion concentration dropped to below 10ppm;

[0052] Saturated sodium carbonate solution was added to the solution after the second-step cyclone electrolysis to adjust the solution pH to 11. After the reaction for 1 hour, MgCO3 was obtained by filtration. 2+ The concentration is reduced to below 20ppm; the existing industry process is used to evaporate and concentrate the liquid after magnesium precipitation to obtain sodium sulfate, and the sodium sulfate is reused in the silicon and aluminum removal section.

[0053] Example 2

[0054] A method for extracting metal from saprolitic laterite nickel ore comprises the following steps:

[0055] Saprolitic laterite nickel ore is beneficiated and ground to produce laterite nickel ore powder. The laterite nickel ore powder is then mixed with water, sulfuric acid, and sodium metabisulfite at a solid-to-liquid ratio of 200 g / L to produce a slurry containing 2 mol / L sulfuric acid and 10 g / L sodium metabisulfite. The slurry is heated to 80°C and stirred for 2 hours. After completion of the reaction, the leaching residue and leachate are filtered and obtained. The contents of metals such as Ni, Co, Mn, and Fe in the leaching residue are measured to be less than 0.05%, and the residual acid in the leachate is approximately 0.3 mol / L. The leached residue can be used as a brickmaking material or directly landfilled.

[0056] 10 g / L of NaF and 10 g / L of Na2SO4 were added to the leachate, and the pH was adjusted to 2 with a 10% NaOH solution. After reacting for 1 hour, the solution was filtered to obtain silica-alumina slag and a desiliconized and desiliconized liquid. The concentrations of residual aluminum and silicon in the desiliconized and desiliconized liquid were measured to be below 5 ppm. Sodium phosphate was further added to the desiliconized and desiliconized liquid to adjust the molar ratio P / Fe in the solution to 1.05. The "two-step method" was used for iron precipitation, and the iron phosphate and the desiliconized liquid were filtered. The Fe / P molar ratio in the iron phosphate was measured to be 0.975, and the content of impurity elements met the requirements of the battery-grade iron phosphate industry standard (HG / T4701-2021).

[0057] The two-step cyclone electrolysis method is used to recover valuable metals from the iron precipitation liquid. The process parameters of the one-step cyclone electrolysis are as follows: the acidity of the iron precipitation liquid is controlled to be 0.3 mol / L, the solution temperature is 35 ° C, and the current density is 600 A / m 2 The electrolysis time is 5h, the cathode is a crude zinc plate, the anode is a lead-silver alloy plate, and zinc-chromium alloy is deposited on the cathode plate during the electrolysis process. The cathode plate replacement cycle is 48h. After the electrolysis is completed, the Zn content in the solution is measured. 2+ The concentration of Cr 3+ The concentration of Ni 2+ 、Co 2+ 、Mn 2+ The loss rate is below 1%. Then, the solution after the first-step cyclone electrolysis is subjected to a second-step cyclone electrolysis to obtain nickel-cobalt alloy, manganese oxide and the solution after the second-step cyclone electrolysis. The process parameters of the second-step cyclone electrolysis are as follows: adjust the solution pH to 2, the solution temperature to 50°C, and the current density to 100A / m 2 The electrolysis time is 8h, the cathode is a stainless steel plate, the anode is a lead-silver alloy plate, and a diaphragm bag is used. The Ni-Co alloy formed by cathode electrodeposition is stripped off in a cycle of 48h to obtain Ni-Co alloy, and MnO2 is collected in the anode diaphragm bag. After the electrolysis is completed, Ni in the solution 2+ 、Co 2+ The ion concentration dropped to below 50ppm, Mn2+ The ion concentration dropped to below 10ppm;

[0058] Saturated sodium carbonate solution was added to the solution after the second-step cyclone electrolysis to adjust the solution pH to 11. After the reaction for 1 hour, MgCO3 was obtained by filtration. 2+ The concentration is reduced to below 20ppm; the existing industry process is used to evaporate and concentrate the liquid after magnesium precipitation to obtain sodium sulfate, and the sodium sulfate is reused in the aluminum silicon removal section.

[0059] Example 3

[0060] A method for extracting metal from saprolitic laterite nickel ore comprises the following steps:

[0061] Saprolitic laterite nickel ore is beneficiated and ground to produce laterite nickel ore powder. The laterite nickel ore powder is then mixed with water, sulfuric acid, and sodium metabisulfite at a solid-to-liquid ratio of 300 g / L to produce a slurry with a sulfuric acid concentration of 3 mol / L and a sodium metabisulfite concentration of 5 g / L. The slurry is heated to 50°C and stirred for 5 hours. After completion of the reaction, the leaching residue and leachate are filtered and obtained. The contents of metals such as Ni, Co, Mn, and Fe in the leaching residue are measured to be less than 0.05%, and the residual acid in the leachate is approximately 0.3 mol / L. The leached residue can be used as a brickmaking material or directly landfilled.

[0062] 20g / L of NaF and 10g / L of Na2SO4 were added to the leachate, and the pH was adjusted to 2 with a 10% NaOH solution. After reacting for 1 hour, the solution was filtered to obtain silica-alumina slag and a desiliconized and desiliconized liquid. The concentrations of residual aluminum and silicon in the desiliconized and desiliconized liquid were measured to be below 5ppm. Sodium phosphate was further added to the desiliconized and desiliconized liquid to adjust the molar ratio P / Fe in the solution to 1.05. The "two-step method" was used for iron precipitation, and the iron phosphate and the desiliconized liquid were filtered. The Fe / P molar ratio in the iron phosphate was measured to be 0.975, and the content of impurity elements met the requirements of the battery-grade iron phosphate industry standard (HG / T4701-2021).

[0063] The two-step cyclone electrolysis method is used to recover valuable metals from the iron precipitation liquid. The process parameters of the one-step cyclone electrolysis are as follows: the acidity of the iron precipitation liquid is controlled to be 0.1 mol / L, the solution temperature is 35 ° C, and the current density is 400 A / m 2 The electrolysis time is 10h, the cathode is a crude zinc plate, the anode is a lead-silver alloy plate, and zinc-chromium alloy is deposited on the cathode plate during the electrolysis process. The cathode plate replacement cycle is 48h. After the electrolysis is completed, the Zn content in the solution is measured. 2+ The concentration of Cr 3+ The concentration of Ni 2+ 、Co 2+ 、Mn 2+The loss rate is below 1%. Then, the solution after the first-step cyclone electrolysis is subjected to a second-step cyclone electrolysis to obtain nickel-cobalt alloy, manganese oxide and the solution after the second-step cyclone electrolysis. The process parameters of the second-step cyclone electrolysis are as follows: adjust the solution pH to 4, the solution temperature to 50°C, and the current density to 200A / m 2 The electrolysis time is 10h, the cathode is a stainless steel plate, the anode is a lead-silver alloy plate, and a diaphragm bag is used. The Ni-Co alloy formed by cathode electrodeposition is stripped off in a cycle of 48h to obtain Ni-Co alloy, and MnO2 is collected in the anode diaphragm bag. After the electrolysis is completed, Ni in the solution 2+ 、Co 2+ The ion concentration dropped to below 50ppm, Mn 2+ The ion concentration dropped to below 10ppm;

[0064] Saturated sodium carbonate solution was added to the solution after the second-step cyclonic electrolysis to adjust the solution pH to 11. After the reaction for 1 hour, MgCO3 was obtained by filtration. 2+ The concentration is reduced to below 20ppm; the existing industry process is used to evaporate and concentrate the liquid after magnesium precipitation to obtain sodium sulfate, and the sodium sulfate is reused in the aluminum silicon removal section.

[0065] The extraction rates of valuable metals from saprolitic laterite nickel ore in Examples 1 to 3 are shown in Table 2 below, where the extraction rates of Zn and Cr are the ratio of the mass of the Zn-Cr alloy stripped from the cathode plate of the first-step cyclone electrolysis to the total amount of Zn and Cr in the laterite nickel ore; and the extraction rates of Ni and Co are the ratio of the total mass of the Ni-Co alloy stripped from the cathode plate of the second-step cyclone electrolysis to the total amount of Ni and Co in the laterite nickel ore.

[0066] Table 2 Extraction rate of various valuable metals

[0067] As can be seen from the above table, through the process steps provided by the present invention, an effective extraction rate of Ni and Co exceeding 95%, an effective extraction rate of Mn exceeding 90%, and an effective extraction rate of Zn and Cr exceeding 98% in the whole process are achieved.

[0068] In summary, the present invention: (1) avoids the large amount of energy consumption caused by high-pressure leaching in the existing process by means of normal pressure leaching, thereby promoting carbon dioxide emission reduction.

[0069] (2) During the processing, the resource utilization of iron is realized simultaneously to prepare battery-grade iron phosphate, and magnesium is prepared into magnesium carbonate. No additional smelting slag recycling process is required, which greatly reduces the complexity of the process flow and has more economic cost advantages.

[0070] (3) The cyclone electrolysis technology was introduced into the field of laterite nickel ore smelting. The two-step cyclone electrolysis solved the problem of separation of zinc chromium and nickel cobalt manganese in the traditional smelting process, and obtained high-purity Zn-Cr alloy and Ni-Co alloy respectively. Manganese was extracted and utilized in the form of MnO2 at the same time.

[0071] 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.

[0072] 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 metal from saprolitic laterite nickel ore, characterized in that: The following steps are involved: (1) beneficiating and grinding the saprolite-type laterite-nickel ore to obtain laterite-nickel ore powder; (2) mixing laterite nickel ore powder, water, acid and a reducing agent to prepare a slurry, and then performing normal pressure acid leaching to obtain leaching residue and leaching liquid; (3) adding a soluble fluoride salt and a soluble sodium salt to the leachate to separate the solid and the liquid to obtain a silicoaluminate slag and a liquid after the silicoaluminate removal; the silicoaluminate slag contains sodium fluoroaluminate and sodium fluorosilicate; (4) adding a phosphorus source to the liquid after silicon and aluminum are removed, and performing solid-liquid separation to obtain iron phosphate and iron precipitation liquid; (5) subjecting the iron precipitation liquid to one-step cyclone electrolysis to obtain a zinc-chromium alloy and a one-step cyclone electrolysis liquid; (6) performing a second-step cyclone electrolysis on the first-step cyclone electrolysis solution to obtain a nickel-cobalt alloy, manganese oxide, and a second-step cyclone electrolysis solution; (7) adding sodium carbonate to the liquid after the two-step cyclonic electrolysis to carry out a precipitation reaction to obtain magnesium carbonate and a magnesium precipitation liquid.

2. The method for extracting metal from saprolite-type laterite nickel ore according to claim 1, characterized in that: In step (2), the acid is an organic acid or an inorganic acid, and the reducing agent is one or more of sodium sulfite, sodium bisulfite, sodium pyrosulfite, iron powder, and ferrous sulfate.

3. The method for extracting metal from saprolite-type laterite nickel ore according to claim 1, characterized in that: In step (2), the concentration of the acid is 1-3 mol / L, the amount of the reducing agent is 5-20 g / L, and the solid-liquid ratio of the slurry is 50-300 g / L.

4. The method for extracting metal from saprolite-type laterite nickel ore according to claim 1, characterized in that: The leaching temperature of the normal pressure acid leaching in step (2) is 50-90° C., and the leaching time is 1-5 h.

5. The method for extracting metal from saprolite-type laterite nickel ore according to claim 1, characterized in that: The soluble fluoride salt in step (3) is at least one of sodium fluoride, potassium fluoride and ammonium fluoride; the soluble sodium salt is at least one of sodium fluoride, sodium chloride and sodium sulfate.

6. The method for extracting metal from saprolite-type laterite nickel ore according to claim 1, characterized in that: In step (3), the amount of the soluble fluoride salt is 3-20 g / L, and the amount of the soluble sodium salt is 5-20 g / L; and the pH of the leaching solution is controlled to be 1-3 using a dilute alkali solution, and the reaction is carried out at room temperature for 0.5-3 hours.

7. The method for extracting metal from saprolite-type laterite nickel ore according to claim 1, characterized in that: The phosphorus source in step (4) is one or more of phosphoric acid, sodium phosphate, diammonium phosphate, monoammonium phosphate, and ammonium phosphate; the molar ratio of the phosphorus source to the iron element in the leaching solution is (1-1.1):

1.

8. The method for extracting metal from saprolite-type laterite nickel ore according to claim 1, characterized in that: In the one-step cyclone electrolysis of step (5), the acidity of the iron precipitation liquid is 0.1-0.3 mol / L, the temperature is 30-40°C, and the current density is 400-600 A / m 2 , the electrolysis time is 5-10h.

9. The method for extracting metal from saprolite-type laterite nickel ore according to claim 1, characterized in that: In the two-step cyclone electrolysis of step (6), the pH of the solution after the one-step cyclone electrolysis is controlled to be 2-4, the temperature to be 40-50°C, and the current density to be 100-200A / m 2 , the electrolysis time is 5-10h.

10. The method for extracting metal from saprolitic laterite nickel ore according to claim 1, characterized in that: The method also includes evaporating and concentrating the magnesium precipitation liquid to obtain sodium sulfate, and reusing the sodium sulfate as a sodium salt for silicon and aluminum removal in step (3).

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