A method for leaching high calcium magnesium alkaline gangue type nickel-cobalt-copper sulfide ore under neutral or alkaline conditions

Abstract

The application discloses a method for leaching high calcium magnesium alkaline gangue type nickel-cobalt-copper sulfide under neutral or alkaline conditions, which comprises the following steps: S1, collecting high calcium magnesium alkaline gangue type nickel-cobalt-copper sulfide ore, performing size-reducing, crushing and grinding treatment on the ore to obtain a sample; preparing a composite leaching agent; the composite leaching agent contains an oxidizing agent and a complexing agent / ligand; the pH value of the composite leaching agent is 7-12; S2, adding the sample obtained in the step S1 into the composite leaching agent according to a preset solid-liquid ratio, uniformly mixing, performing leaching reaction, and separating liquid and solid after the reaction to obtain a leaching solution rich in valuable metals. The application effectively realizes low-cost, green and efficient leaching of high calcium magnesium alkaline gangue type nickel-cobalt-copper sulfide, and can obtain a leaching solution with low calcium and magnesium impurity metal content and high nickel, cobalt and copper valuable metal content.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing and hydrometallurgical utilization, specifically relating to a method for leaching high-calcium-magnesium alkaline gangue-type nickel-cobalt-copper sulfide ores under neutral or alkaline conditions. Background Technology

[0002] Nickel, cobalt, and copper play a vital role in my country's modern industrial development, serving as indispensable elements for heavy industry, energy transportation, defense, and new energy battery industries. In recent years, the new energy battery industry has experienced rapid growth, with nickel and cobalt, as key cathode materials for lithium batteries, seeing increasing demand in the electric vehicle sector. Copper, as an excellent conductor of electricity, is also crucial for power transmission infrastructure. However, the global distribution of nickel, cobalt, and copper mineral resources is highly uneven. Nickel reserves are mainly located in Australia, Indonesia, and the Philippines, while cobalt reserves are concentrated in the Congo region, and cobalt is typically produced as a byproduct of copper, nickel, and other metals. Currently, most of the large nickel-cobalt-copper complex veins discovered in my country are sulfide deposits with high calcium and magnesium content, often mixed with large amounts of alkaline gangue, forming typical high-calcium, magnesium, and alkaline gangue-type sulfide nickel-cobalt-copper deposits. For example, the Jinchuan nickel-cobalt-copper sulfide vein in Gansu Province has MgO and CaO contents as high as approximately 30%. This uneven distribution of nickel-cobalt-copper resources has led to a severe shortage of these resources in my country, resulting in a long-term reliance on imports.

[0003] Traditional processes for extracting valuable metals from alkaline gangue-type nickel-cobalt-copper sulfide ores include beneficiation-pyrometallurgical processes and acidic hydrometallurgical processes. The beneficiation-pyrometallurgical process requires the ore to contain more than 20% valuable metals after flotation. However, calcium and magnesium ions readily dissolve during flotation, leading to the adsorption of intermediate substances such as calcium sulfate and magnesium hydroxide on the mineral surface, significantly impacting flotation performance. Furthermore, the high clay content and fine particle size of alkaline gangue-type nickel-cobalt-copper sulfide ores easily cause flotation slime to form a coating on the mineral surface, hindering the effective reaction between flotation reagents and minerals, resulting in excessive reagent consumption and a significant reduction in flotation efficiency. In recent years, with the continuous advancement of "dual-carbon" construction, hydrometallurgy has been gradually applied to the extraction of complex mineral resources due to its advantages in low cost, low carbon footprint, and environmental friendliness. Acidic hydrometallurgical processes, in particular, utilize the oxidation-reduction and bonding / complexation effects of acidic systems to leach valuable metal elements from ores. However, for high-calcium-magnesium alkaline gangue-type nickel-cobalt-copper sulfide ores, traditional acidic hydrometallurgical processes present challenges such as high acid consumption, passivation of the mineral leaching interface, and high calcium and magnesium content in the leachate. Furthermore, in acidic systems, potassium ferric sulfate readily forms on the ore surface, adsorbing large amounts of valuable metal ions from the leachate, leading to a decrease in leaching rate. Therefore, currently, neither traditional beneficiation-smelting processes nor acidic hydrometallurgical processes can achieve economical and green mining of high-calcium-magnesium alkaline gangue-type nickel-cobalt-copper sulfide ores, necessitating the research of new leaching systems to treat this type of resource. Summary of the Invention

[0004] The purpose of this invention is to provide a method for leaching high-calcium-magnesium alkaline gangue-type nickel-cobalt-copper sulfide under neutral or alkaline conditions, in order to solve the bottlenecks and challenges that are difficult to overcome in the current conventional acidic leaching system for high-calcium-magnesium alkaline gangue-type nickel-cobalt-copper sulfide ores, such as high sulfuric acid consumption, continuous deterioration of the permeability of the leaching pile, passivation of the leaching interface of valuable minerals, and excessively high calcium and magnesium content in the leachate.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for leaching high-calcium-magnesium alkaline gangue-type nickel-cobalt-copper sulfide ores under neutral or alkaline conditions, comprising the following steps:

[0007] S1. Collect high-calcium-magnesium alkaline gangue-type nickel-cobalt-copper sulfide ore, and process the ore by reduction, crushing, and grinding to obtain ore samples; prepare a composite leaching agent; the composite leaching agent contains an oxidizing agent and a complexing agent / ligand; the pH value of the composite leaching agent is 7-12;

[0008] S2. Add the mineral sample described in step S1 to the composite leaching agent according to the preset solid-liquid ratio, mix evenly, carry out the leaching reaction, and after the reaction is completed, separate the liquid and solid to obtain a leachate rich in valuable metals.

[0009] In step S1, the main characteristics of the high-calcium-magnesium alkaline gangue-type nickel-cobalt-copper sulfide ore are that the ore has a high content of calcium and magnesium elements (>10%), contains a large amount of alkaline minerals such as serpentine, chlorite, forsterite and dolomite, and in addition, the ore exhibits obvious high sulfur characteristics (>3%), and the valuable metals of nickel, cobalt and copper are mostly present in the form of sulfide ore.

[0010] Furthermore, in step S1, the crushing equipment includes conventional crushing equipment such as jaw crushers, gyratory crushers, cone crushers, and roller crushers, and the grinding equipment includes conventional grinding equipment such as ball mills, rod mills, and autogenous mills.

[0011] Furthermore, in step S1, the proportion of the mineral sample with a particle size of less than 0.074 mm is higher than 50%.

[0012] Further, in step S1, the oxidant includes at least one of the following oxidants that have oxidizing properties under neutral or alkaline conditions: persulfate, perdisulfate, permanganate, hydrogen peroxide, peracetic acid, sodium percarbonate, etc.; the complexing agent / ligand includes at least one of a series of small molecule ligands that have complexing / coordination effects under neutral or alkaline conditions: amino acids, citrate, malate, gluconate, ammonia, etc.

[0013] Further, in step S1, the concentration of the oxidant in the composite leaching agent is 0.05-0.5 mol / L, and the concentration of the complexing agent / ligand is 0.1-0.5 mol / L.

[0014] Further, in step S1, the preparation of the composite leaching agent includes: dissolving the oxidant and complexing agent / ligand in ultrapure water, mixing them evenly, and adjusting the pH value of the solution to 7-12 with an alkaline / acidic substance to obtain the composite leaching agent.

[0015] In hydrometallurgical processes, effectively transferring the target metal from the ore into the leachate is a crucial step in determining the feasibility of the leaching process. In the high-calcium, magnesium-alkaline gangue-type nickel-cobalt-copper sulfide of this invention, all elements are in a low-valence / reduced state. Oxidation is necessary to break chemical bonds (providing oxidants such as O2 / electron acceptors) to achieve the dissolution of valuable elements from the mineral. Therefore, this invention uses oxidants with oxidizing properties under neutral or alkaline conditions, such as sulfates, persulfates, permanganates, hydrogen peroxide, peracetic acid, and sodium percarbonate. These oxidants can destroy sulfides and mineral lattices in the ore without pre-acidification, thereby increasing the dissolution rate of the ore. Furthermore, preventing the precipitation of valuable metal ions under neutral or alkaline conditions is also a key factor affecting leaching performance. This invention uses a series of small-molecule complexes, such as amino acids, citric acid, and gluconic acid, to complex the valuable metal elements in the leachate, thereby forming stable complexes in the solution. For example, under alkaline conditions, glycine ligands can selectively complex nickel, cobalt, and copper metal elements, thereby achieving efficient separation of valuable metal elements from ores.

[0016] Further, in step S2, the solid-liquid ratio of the mineral sample to the composite leaching agent is 1 g:(100-1) mL, the leaching temperature is 15-80℃, and the leaching time is 12-96 h. The higher the solid-liquid ratio, the higher the temperature, and the longer the leaching time, the more significantly the leaching effect is promoted. Uniform mixing of the system can be achieved through one or more methods such as stirring, shaking, and aeration. Specifically, the stirring or shaking speed is 10-1000 rpm, and the aeration rate is 1.0-3.0 m³ / s. 3 / min (based on 100m) 3 Leachate calculation).

[0017] Further, in step S2, the liquid-solid separation method includes gravity sedimentation, centrifugation, and filtration. Specifically, the gravity sedimentation method has a settling time of 0.5–2 hours; the centrifugation method has a rotation speed of 2000–10000 rpm, a time of 2–10 minutes, and a temperature of 15–35°C; and the filtration method uses filter paper for separation through qualitative analysis.

[0018] The principle of this invention:

[0019] This invention addresses the problems of high acid consumption, high calcium and magnesium content in the leachate, and passivation of the leaching interface in current acidic leaching systems for high-calcium-magnesium alkaline gangue nickel-cobalt-copper sulfide ores. It constructs a leaching system based on a combined oxidation-complexation / coordination reaction principle under neutral or alkaline conditions. On one hand, this leaching system utilizes the oxidizing properties (E0.05) of strong oxidants such as persulfate, potassium permanganate, and hydrogen peroxide. RHE (Persulfate) = 1.77–2.1 V, E RHE(KMnO4)=0.588V, E RHE (H2O2) = 1.8V) and free radicals generated by activation by transition metal ions (E RHE (SO4 - ·)=2.5~3.1V, E RHE The oxidizing property of (·OH)=2.8V) allows for the removal of sulfides (E) in the ore without the need for pre-acidification. RHE The oxidation process (SO₄²⁻) at -0.445V leads to the destruction of the mineral matrix and crystal lattice. In this reaction, the oxidizing chemical or free radical donates oxygen ions and unpaired electrons, which accept electrons from the sulfide, removing it to form sulfate ions (SO₄²⁻). 2- Other sulfide oxide products. Reactions of other elements in the mineral matrix and crystal lattice also involve electron transfer, leading to the destruction of the matrix and crystal lattice, thus achieving the dissolution of valuable elements. On the other hand, by introducing small molecule complexing agents such as amino acids, citric acid, and gluconic acid, various stable complexes can be formed with valuable metal ions in neutral or alkaline leachates, such as Me(Gly). i Z+ Me(CA) i Z+ andMe(GA) i Z+ Specifically, small molecule complexing agents (usually oxygen, nitrogen, or sulfur) donate lone pairs of electrons to form complexes with transition metal ions. Since transition metal ions typically have unfilled d orbitals that can accommodate these electrons, these electrons interact with the empty orbitals of the metal ions to form stable metal-ligand coordination bonds. Once the coordination bond between the metal and the ligand is formed, the transition metal ion is surrounded by the ligand, forming a stable complex. Finally, solid-liquid separation is used to transfer valuable metal elements such as nickel, cobalt, and copper from high-calcium, magnesium-rich alkaline gangue-type sulfide ores (solid phase) to a leaching solution with low impurity content (liquid phase).

[0020] This invention has at least the following technical effects:

[0021] (1) This invention effectively avoids the problems of low recovery rate, high production cost and serious environmental pollution faced by high calcium and magnesium alkaline gangue type nickel cobalt copper sulfide ores in the traditional flotation-pyrometallurgical process.

[0022] (2) The present invention effectively solves the problems of high acid consumption and passivation of valuable mineral leaching interface in traditional acidic hydrometallurgical processes for high-calcium magnesium alkaline gangue-type nickel-cobalt-copper sulfide ores.

[0023] (3) This invention effectively achieves low-cost, green and environmentally friendly, and efficient leaching of high-calcium and magnesium alkaline gangue-type nickel-cobalt-copper sulfide ores, and can obtain leachate with low calcium and magnesium impurity metal content and high nickel, cobalt and copper valuable metal content. Detailed Implementation

[0024] To make the technical objectives, technical solutions, and technical effects of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art in conjunction with the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] The weights of the relevant components mentioned in the embodiments of this invention can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this invention is within the scope disclosed in the embodiments of this invention. Specifically, the weights mentioned in the embodiments of this invention can be well-known units of mass in the chemical industry, such as μg, mg, g, and kg.

[0026] The high-calcium-magnesium alkaline gangue-type nickel-cobalt-copper sulfide ore in the following examples was selected from Jinchuan No. 2 Mine in Jinchuan District, Jinchang City, Gansu Province. Its main characteristics are high calcium and magnesium content (>10%), large amount of alkaline minerals such as serpentine, chlorite, forsterite and dolomite, and obvious high sulfur content (>3%). Most of the valuable metals such as nickel, cobalt and copper are present as sulfide minerals.

[0027] Example 1

[0028] High-calcium, magnesium-rich alkaline gangue-type nickel-cobalt-copper sulfide ore from the mining area was collected, dried, and preserved. It was then mixed and reduced using a "quartering method," followed by crushing and grinding with a jaw crusher and vibratory mill to obtain a sample with a particle size of less than 0.074 mm accounting for more than 60%. 5g of the ore sample, 2g of ammonium persulfate, and 2g of glycine were placed in a 250mL conical flask containing 100mL of ultrapure water and stirred thoroughly. The pH of the leaching system was then adjusted to 9.0 using a 1M sodium hydroxide / hydrochloric acid solution to obtain an alkaline leaching system. The leaching system was placed in a constant-temperature shaker at 180rpm and 60℃. The pH of the leaching system was readjusted to 9.0 at 2h, 6h, 24h, and 48h of leaching, for a total reaction time of 72h. After the reaction, the leaching system was separated into liquid and solid phases by high-speed centrifugation at 5000rpm and 25℃ to obtain the leachate. Tests showed that the leaching rate of calcium and magnesium impurities was less than 30% throughout the leaching process, while the leaching rates of valuable metals such as nickel, cobalt, and copper were 98.1%, 89.8%, and 83.1%, respectively.

[0029] Comparative Example 1

[0030] The leaching of the same mineral sample as in Example 1 was performed using a conventional acidic method. 5g of mineral sample was leached in a 250mL Erlenmeyer flask at a liquid-to-solid ratio of 20:1, with a sulfuric acid leaching agent dosage of 0.45g / g. The leaching time was 24 hours, with the shaker speed set at 180rpm and the temperature at 60℃. After the reaction, the leaching system was separated into liquid and solid phases by high-speed centrifugation at 5000rpm and the temperature at 25℃. Throughout the leaching process, the leaching rates of calcium and magnesium impurities were >70%, while the leaching rates of nickel, cobalt, and copper were 28.4%, 11.3%, and 31.9%, respectively.

[0031] Comparative Example 2

[0032] 5g of the same mineral sample as in Example 1 and 2g of glycine were placed in a 250mL Erlenmeyer flask containing 100mL of ultrapure water and stirred until homogeneous. The pH of the leaching system was then adjusted to 9.0 using a 1M sodium hydroxide / hydrochloric acid solution to obtain an alkaline leaching system. The leaching system was placed in a constant-temperature shaker at 180rpm and 60℃. The pH of the leaching system was readjusted to 9.0 at 2h, 6h, 24h, and 48h of leaching, for a total reaction time of 72h. After the reaction, the leaching system was separated into liquid and solid phases by high-speed centrifugation at 5000rpm and 25℃ to obtain the leachate. The leaching rates of calcium and magnesium impurities were <30%, while the leaching rates of nickel, cobalt, and copper were 31.1%, 19.9%, and 17.3%, respectively.

[0033] Comparative Example 3

[0034] 5g of the same mineral sample as in Example 1 and 2g of ammonium persulfate were placed in a 250mL Erlenmeyer flask containing 100mL of ultrapure water and stirred until homogeneous. The pH of the leaching system was then adjusted to 9.0 using a 1M sodium hydroxide / hydrochloric acid solution to obtain an alkaline leaching system. The leaching system was placed in a constant-temperature shaker at 180rpm and 60℃. The pH of the leaching system was readjusted to 9.0 at 2h, 6h, 24h, and 48h of leaching, for a total reaction time of 72h. After the reaction, the leaching system was separated into liquid and solid phases by high-speed centrifugation at 5000rpm and 25℃ to obtain the leachate. Throughout the leaching process, the leaching rates of calcium and magnesium impurities were >40%, and the leaching rates of nickel, cobalt, and copper were 21.3%, 28.5%, and 12.8%, respectively.

[0035] As can be seen from Examples 1 and Comparative Examples 1-3, compared with the traditional acidic leaching system (Comparative Example 1), the leaching method based on the oxidation-complexation / coordination principle under alkaline conditions (Example 1) can effectively leach valuable metals in high-calcium-magnesium alkaline gangue sulfide ores. However, using only the complexation / coordination leaching system (Comparative Example 2) or the oxidation leaching system (Comparative Example 3) cannot efficiently leach valuable metals from high-calcium-magnesium alkaline gangue sulfide ores. This is because the former only involves complexation / coordination, which cannot effectively destroy the ore matrix and crystal structure, making it difficult to leach valuable metals; while the latter, although it can effectively oxidize and destroy ore sulfides, easily forms hydroxide precipitates under alkaline conditions, thus reducing the leaching rate of valuable metals.

[0036] Example 2

[0037] 5g of the same mineral sample as in Example 1, 2g of potassium persulfate, and 2g of glycine were placed in a 250mL Erlenmeyer flask containing 100mL of ultrapure water and stirred until homogeneous. The pH of the leaching system was then adjusted to 9.0 using a 1M sodium hydroxide / hydrochloric acid solution to obtain an alkaline leaching system. The leaching system was placed in a constant-temperature shaker at 180rpm and 60℃. The pH of the leaching system was readjusted to 9.0 at 2h, 6h, 24h, and 48h of leaching, for a total reaction time of 72h. After the reaction, the leaching system was separated into liquid and solid phases by high-speed centrifugation at 5000rpm and 25℃ to obtain the leachate. Testing showed that the leaching rates of calcium and magnesium impurities were <30%, while the leaching rates of nickel, cobalt, and copper were 78.5%, 81.2%, and 81.6%, respectively.

[0038] Comparative Example 4

[0039] 5g of the same mineral sample as in Example 1 and 2g of potassium persulfate were placed in a 250mL Erlenmeyer flask containing 100mL of ultrapure water and stirred until homogeneous. The pH of the leaching system was then adjusted to 9.0 using a 1M sodium hydroxide / hydrochloric acid solution to obtain an alkaline leaching system. The leaching system was placed in a constant-temperature shaker at 180rpm and 60℃. The pH of the leaching system was readjusted to 9.0 at 2h, 6h, 24h, and 48h of leaching, for a total reaction time of 72h. After the reaction, the leaching system was separated into liquid and solid phases by high-speed centrifugation at 5000rpm and 25℃ to obtain the leachate. Testing showed that the leaching rates of calcium and magnesium impurities were >30%, while the leaching rates of nickel, cobalt, and copper were 8.1%, 11.4%, and 17.4%, respectively.

[0040] Example 3

[0041] High-calcium, magnesium-rich alkaline gangue-type nickel-cobalt-copper sulfide ore from the mining area was collected, dried, and preserved. It was then mixed and reduced using a "quartering method," followed by crushing and grinding with a jaw crusher and vibratory mill to obtain a sample with a particle size of less than 0.074 mm accounting for more than 60%. 5g of the ore sample, 5g of sodium percarbonate, and 2g of glycine were placed in a 250mL conical flask containing 100mL of ultrapure water and stirred thoroughly. The pH of the leaching system was then adjusted to 9.0 using a 1M sodium hydroxide / hydrochloric acid solution to obtain an alkaline leaching system. The leaching system was placed in a constant-temperature shaker at 180rpm and 60℃. The pH of the leaching system was readjusted to 9.0 at 2h, 6h, 24h, and 48h of leaching, for a total reaction time of 72h. After the reaction, the leaching system was separated into liquid and solid phases by high-speed centrifugation at 5000rpm and 25℃ to obtain the leachate. Tests showed that the leaching rate of calcium and magnesium impurities was less than 30% throughout the leaching process, while the leaching rates of valuable metals such as nickel, cobalt, and copper were 73.4%, 80.4%, and 81.3%, respectively.

[0042] Comparative Example 5

[0043] 5g of the same mineral sample as in Example 3 and 5g of sodium percarbonate were placed in a 250mL Erlenmeyer flask containing 100mL of ultrapure water and stirred until homogeneous. The pH of the leaching system was then adjusted to 9.0 using a 1M sodium hydroxide / hydrochloric acid solution to obtain an alkaline leaching system. The leaching system was placed in a constant-temperature shaker at 180rpm and 60℃. The pH of the leaching system was readjusted to 9.0 at 2h, 6h, 24h, and 48h of leaching, for a total reaction time of 72h. After the reaction, the leaching system was separated into liquid and solid phases by high-speed centrifugation at 5000rpm and 25℃ to obtain the leachate. Testing showed that the leaching rates of calcium and magnesium impurities were <30%, while the leaching rates of nickel, cobalt, and copper were 22.1%, 31.2%, and 25.3%, respectively.

[0044] Example 4

[0045] High-calcium, magnesium-rich alkaline gangue-type nickel-cobalt-copper sulfide ore from the mining area was collected, dried, and preserved. It was then mixed and reduced using a "quartering method," followed by crushing and grinding with a jaw crusher and vibratory mill to obtain a sample with a particle size of less than 0.074 mm accounting for more than 60%. 5g of the ore sample, 2g of ammonium persulfate, and 4g of ammonium citrate were placed in a 250mL conical flask containing 100mL of ultrapure water and stirred thoroughly. The pH of the leaching system was then adjusted to 9.0 using a 1M sodium hydroxide / hydrochloric acid solution to obtain an alkaline leaching system. The leaching system was placed in a constant-temperature shaker at 180rpm and 60℃. The pH of the leaching system was readjusted to 9.0 at 2h, 6h, 24h, and 48h of leaching, for a total reaction time of 72h. After the reaction, the leaching system was separated into liquid and solid phases by high-speed centrifugation at 5000rpm and 25℃ to obtain the leachate. Tests showed that the leaching rate of calcium and magnesium impurities was less than 30% throughout the leaching process, while the leaching rates of nickel, cobalt, and copper were 84.4%, 87.8%, and 75.6%, respectively.

[0046] Comparative Example 6

[0047] 5g of the same mineral sample as in Example 4 and 4g of ammonium citrate were placed in a 250mL Erlenmeyer flask containing 100mL of ultrapure water and stirred until homogeneous. The pH of the leaching system was then adjusted to 9.0 using a 1M sodium hydroxide / hydrochloric acid solution to obtain an alkaline leaching system. The leaching system was placed in a constant-temperature shaker at 180rpm and 60℃. The pH of the leaching system was readjusted to 9.0 at 2h, 6h, 24h, and 48h of leaching, for a total reaction time of 72h. After the reaction, the leaching system was separated into liquid and solid phases by high-speed centrifugation at 5000rpm and 25℃ to obtain the leachate. Testing showed that the leaching rates of calcium and magnesium impurities were <40%, while the leaching rates of nickel, cobalt, and copper were 23.1%, 31.4%, and 29.7%, respectively.

[0048] Example 5

[0049] High-calcium, magnesium-rich alkaline gangue-type nickel-cobalt-copper sulfide ore from the mining area was collected, dried, and preserved. It was then mixed and reduced using a "quartering method," followed by crushing and grinding with a jaw crusher and vibratory mill to obtain a sample with a particle size of less than 0.074 mm accounting for more than 60%. 5g of the ore sample, 2g of potassium persulfate, and 4g of ammonium citrate were placed in a 250mL conical flask containing 100mL of ultrapure water and stirred thoroughly. The pH of the leaching system was then adjusted to 9.0 using a 1M sodium hydroxide / hydrochloric acid solution to obtain an alkaline leaching system. The leaching system was placed in a constant-temperature shaker at 180rpm and 60℃. The pH of the leaching system was readjusted to 9.0 at 2h, 6h, 24h, and 48h of leaching, for a total reaction time of 72h. After the reaction, the leaching system was separated into liquid and solid phases by high-speed centrifugation at 5000rpm and 25℃ to obtain the leachate. Tests showed that the leaching rate of calcium and magnesium impurities was less than 30% throughout the leaching process, while the leaching rates of valuable metals such as nickel, cobalt, and copper were 78.1%, 90.4%, and 85.3%, respectively.

[0050] Example 6

[0051] High-calcium, magnesium-rich alkaline gangue-type nickel-cobalt-copper sulfide ore from the mining area was collected, dried, and preserved. It was then mixed and reduced using a "quartering method," followed by crushing and grinding with a jaw crusher and vibratory mill to obtain a sample with a particle size of less than 0.074 mm accounting for more than 60%. 5g of the ore sample, 5g of sodium percarbonate, and 4g of ammonium citrate were placed in a 250mL conical flask containing 100mL of ultrapure water and stirred thoroughly. The pH of the leaching system was then adjusted to 9.0 using a 1M sodium hydroxide / hydrochloric acid solution to obtain an alkaline leaching system. The leaching system was placed in a constant-temperature shaker at 180rpm and 60℃. The pH of the leaching system was readjusted to 9.0 at 2h, 6h, 24h, and 48h of leaching, for a total reaction time of 72h. After the reaction, the leaching system was separated into liquid and solid phases by high-speed centrifugation at 5000rpm and 25℃ to obtain the leachate. Tests showed that the leaching rate of calcium and magnesium impurities was less than 30% throughout the leaching process, while the leaching rates of valuable metals such as nickel, cobalt, and copper were 76.8%, 89.8%, and 81.6%, respectively.

[0052] Example 7

[0053] 5g of the same mineral sample as in Example 1, 2g of ammonium persulfate, and 2g of glycine were placed in a 250mL Erlenmeyer flask containing 100mL of ultrapure water and stirred until homogeneous. The pH of the leaching system was then adjusted to 7.0 using a 1M sodium hydroxide / hydrochloric acid solution to obtain a neutral leaching system. The leaching system was placed in a constant-temperature shaker at 180rpm and 25℃. The pH of the leaching system was readjusted to 7.0 at 2h, 6h, and 12h of leaching, for a total reaction time of 24h. After the reaction, the leaching system was separated into liquid and solid phases by high-speed centrifugation at 5000rpm and 25℃ to obtain the leachate. Testing showed that the leaching rates of calcium and magnesium impurities were <30%, while the leaching rates of nickel, cobalt, and copper were 83.6%, 81.1%, and 79.7%, respectively.

[0054] Example 8

[0055] 5g of the same mineral sample as in Example 1, 2g of ammonium persulfate, and 2g of glycine were placed in a 250mL Erlenmeyer flask containing 100mL of ultrapure water and stirred until homogeneous. The pH of the leaching system was then adjusted to 12.0 using a 1M sodium hydroxide / hydrochloric acid solution to obtain an alkaline leaching system. The leaching system was placed in a constant-temperature shaker at 180rpm and 70℃. The pH of the leaching system was readjusted to 12.0 at 2h, 6h, 24h, 48h, and 72h of leaching, for a total reaction time of 96h. After the reaction, the leaching system was separated into liquid and solid phases by high-speed centrifugation at 5000rpm and 25℃ to obtain the leachate. Testing showed that the leaching rates of calcium and magnesium impurities were <30%, while the leaching rates of nickel, cobalt, and copper were 71.0%, 67.4%, and 69.9%, respectively.

Claims

1. A method for leaching high-calcium-magnesium alkaline gangue-type nickel-cobalt-copper sulfide ores under neutral or alkaline conditions, comprising the following steps: S1. Collect high-calcium-magnesium alkaline gangue-type nickel-cobalt-copper sulfide ore, and perform reduction, crushing, and grinding on the ore to obtain ore samples; A composite leaching agent is prepared; the composite leaching agent contains an oxidizing agent and a complexing agent / ligand; the pH value of the composite leaching agent is 7 to 12; S2. Add the mineral sample described in step S1 to the composite leaching agent according to the preset solid-liquid ratio, mix evenly, carry out the leaching reaction, and after the reaction is completed, separate the liquid and solid to obtain a leachate rich in valuable metals. In step S1, the oxidant is an oxidizing agent that has oxidizing properties under neutral or alkaline conditions, including one or more of persulfate, perdisulfate, permanganate, hydrogen peroxide, peracetic acid, and sodium percarbonate; the complexing agent / ligand is a small molecule ligand that has complexing / coordination effects under neutral or alkaline conditions, including one or more of amino acids, citrate, malate, and gluconate; in the composite leaching agent, the concentration of the oxidant is 0.05 ~ 0.5 mol / L, and the concentration of the complexing agent / ligand is 0.1 ~ 0.5 mol / L.

2. The method of claim 1, wherein, In step S1, the preparation of the composite leaching agent includes: dissolving the oxidant and complexing agent / ligand in ultrapure water, mixing them evenly, and adjusting the pH of the solution to 7-12 with an alkaline / acidic substance to obtain the composite leaching agent.

3. The method of claim 1, wherein, In step S1, the crushing equipment includes at least one of a jaw crusher, a gyratory crusher, a cone crusher, and a roller crusher; the grinding equipment includes at least one of a ball mill, a rod mill, and an autogenous mill; and the proportion of the ore sample with a particle size of less than 0.074 mm is higher than 50%.

4. The method according to claim 1, characterized in that, In step S2, the solid-liquid ratio of the mineral sample to the composite leaching agent is 1g:(100~1)mL; the leaching temperature of the leaching reaction is 15~80℃, and the leaching time is 12~96h.

5. The method according to claim 1, characterized in that, The step S2, the system is mixed uniformly through one or more of stirring, shaking, aeration mode, the specific stirring or shaking speed is 10 ~ 1000 rpm, the aeration amount is between 1.0 ~ 3.0 m 3 / min.

6. The method according to claim 1, characterized in that, In step S2, the liquid-solid separation method includes gravity sedimentation, centrifugal separation, and filtration separation.

7. The method according to claim 6, characterized in that, In step S2, the gravity sedimentation method has a settling time of 0.5 to 2 hours; the centrifugation method has a rotation speed of 2000 to 10000 rpm, a time of 2 to 10 minutes, and a temperature of 15 to 35 ℃; and the filtration method uses filter paper for separation through qualitative analysis.