Wet leaching method for low-copper high-grade matte nickel

Abstract

The invention provides a wet leaching method for low-copper high-grade matte nickel. The wet leaching method for the low-copper high-grade matte nickel comprises the steps that first-stage normal-pressure leaching and solid-liquid separation are conducted on the low-copper high-grade matte nickel, second-stage normal-pressure leaching and solid-liquid separation are conducted on an obtained first slag phase, and second-stage normal-pressure leaching liquid and a second slag phase are obtained; then, after the second slag phase is subjected to size mixing, first-stage oxygen pressure leaching is conducted, solid-liquid separation is conducted, and total first-stage oxygen pressure leaching liquid and leaching slag are obtained; and then, copper removal treatment is conducted on at least one of the second-section normal-pressure leaching liquid and the total first-section oxygen pressure leaching liquid, and the normal-pressure leaching step is conducted again. The wet leaching method of the low-copper high-grade matte nickel comprises two-stage normal pressure leaching and one-stage pressure leaching, the process is simplified, the cost is low, the leaching rate of nickel and cobalt is high, reaction conditions are easy to control, and the problem that copper is accumulated in a system can be solved in time.

Description

Technical Field

[0001] The present invention relates to the field of hydrometallurgy, and in particular, to a method for wet leaching of low-copper nickel matte. Background Art

[0002] At present, nickel matte prepared from general sulfide ores generally has the characteristic of high Cu content, and the Cu grade is mostly between 1.5% and 40%. The wet leaching of such nickel matte usually adopts a treatment process of two-stage atmospheric pressure and two-stage pressure, and industrialization has been achieved. The existing process usually introduces copper in the liquid phase into the slag during oxygen pressure leaching, leaches most of Ni / Co during the first-stage pressure leaching by controlling the reaction conditions, and then recovers the remaining nickel and cobalt during the second-stage pressure leaching.

[0003] Nickel matte prepared from laterite nickel ore has the characteristics of high Ni grade (>60%) and low Cu grade (<0.5%), and at the same time, high contents of metallic nickel and metallic iron. If the original process for treating high-copper nickel matte is adopted, problems such as low recovery rates of nickel and cobalt will occur. During the oxygen pressure leaching reaction, copper remains in the solution due to its low content and inability to enter the slag, and circulates with the production system, resulting in the continuous accumulation of copper in the production system. The second-stage pressure leaching cannot achieve the expected effect due to the high nickel ion concentration. In addition, the existing process has a long flow and a high cost for autoclaves. Summary of the Invention

[0004] The main object of the present invention is to provide a method for wet leaching of low-copper nickel matte to solve the problems in the prior art that there is a lack of a wet leaching process suitable for low-copper nickel matte and the existing process has a high cost.

[0005] To achieve the above object, according to one aspect of the present invention, a method for wet leaching of low-copper nickel matte is provided. The copper content in the low-copper nickel matte is 0.01 - 1.5 wt%, the nickel content is 50 - 85 wt%, and the cobalt content is 0.3 - 3 wt%. The method includes: Step S1, performing first-stage atmospheric leaching and solid-liquid separation on the low-copper nickel matte to obtain a first-stage atmospheric leaching solution and a first slag phase; Step S2, performing second-stage atmospheric leaching and solid-liquid separation on the first slag phase to obtain a second-stage atmospheric leaching solution and a second slag phase; Step S3, slurrying the second slag phase and then performing first-stage oxygen pressure leaching to obtain a slurry. Then, performing solid-liquid separation on the slurry to obtain a total first-stage oxygen pressure leaching solution and a leaching residue; wherein, S4, performing copper removal treatment on at least one of the second-stage atmospheric leaching solution and the total first-stage oxygen pressure leaching solution, and then dividing the total first-stage oxygen pressure leaching solution into a first part of the first-stage oxygen pressure leaching solution and a second part of the first-stage oxygen pressure leaching solution, returning the first part of the first-stage oxygen pressure leaching solution and the second-stage atmospheric leaching solution to Step S1 to participate in the first-stage atmospheric leaching, and returning the second part of the first-stage oxygen pressure leaching solution to Step S2 to participate in the second-stage atmospheric leaching.

[0006] Furthermore, the copper removal treatment is carried out using a reducing agent at a treatment temperature of 50 - 99 °C for a time of 3 - 20 min; preferably, the dosage of the reducing agent is 0.2 - 10 times the weight of copper ions in the liquid phase.

[0007] Furthermore, in step S1, it includes: performing a first-stage atmospheric leaching treatment on low-copper nickel matte using an oxidizing gas, sulfuric acid, a second-stage atmospheric leaching solution, and a first part of the first-stage oxygen pressure leaching solution.

[0008] Furthermore, in step S1, the temperature of the first-stage atmospheric leaching is 50 - 99 °C, the time is 3 - 20 h, the liquid-solid ratio is (4 - 15):1, and the final pH is 5.0 - 6.0; preferably, the oxidizing gas is one or more of air, oxygen, and oxygen-enriched gas, and the volume content of oxygen in the oxygen-enriched gas is 35 - 60%.

[0009] Furthermore, in step S2, performing a second-stage atmospheric leaching treatment on the first slag phase using an oxidizing gas, sulfuric acid, and a second part of the first-stage oxygen pressure leaching solution.

[0010] Furthermore, in step S2, the temperature of the second-stage atmospheric leaching is 50 - 99 °C, the time is 3 - 20 h, the liquid-solid ratio is (4 - 15):1, and the final pH is 0.5 - 2.5; preferably, the oxidizing gas is one or more of air, oxygen, and oxygen-enriched gas, and the volume content of oxygen in the oxygen-enriched gas is 35 - 60%.

[0011] Furthermore, in step S3, the weight ratio of the first part of the first-stage oxygen pressure leaching solution to the second part of the first-stage oxygen pressure leaching solution is (1:3) - (3:1).

[0012] Furthermore, in step S3, the temperature of the first-stage oxygen pressure leaching is 130 - 230 °C, the time is 1 - 10 h, the oxygen partial pressure is 0.05 - 2 MPa, and the liquid-solid ratio is (4 - 30):1.

[0013] Furthermore, in step S4, through the copper removal treatment, a crude copper product with a copper grade of 60 - 97% is obtained.

[0014] Furthermore, in step S3, water is used for pulp mixing treatment.

[0015] The existing hydrometallurgical leaching process for high-ice nickel usually combines two-stage atmospheric pressure + two-stage pressure treatment. According to the material characteristics of the low-copper high-ice nickel to be processed, the present invention improves it to two-stage atmospheric pressure and one-stage pressure leaching, simplifying the process and saving costs. At the same time, the present invention also has the following advantages: By performing solid-liquid separation on the first pulp obtained after two-stage atmospheric pressure leaching and adjusting the pulp of the second slag phase obtained after two-stage atmospheric pressure leaching, the leaching rates of nickel and cobalt are greatly improved; In the one-stage oxygen pressure leaching, there is no need to consider suppressing the leaching of copper, and only the leaching rates of nickel and cobalt need to be considered, so the reaction conditions are easy to control; By introducing a process for copper removal treatment, the problem of copper accumulation in the system is solved. Detailed implementation manners

[0016] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0017] Term explanation:

[0018] Leaching rate: During the leaching process, the weight ratio of the target substance dissolved by the solvent from the solid raw material and transferred to the liquid phase.

[0019] Liquid-solid ratio: The ratio between the amount of liquid used when treating solid materials and the amount of the solid materials. In this application, the unit of the liquid-solid ratio is mL / g.

[0020] To solve the problems in the prior art as described above, the present invention provides a hydrometallurgical leaching method for low-copper high-ice nickel. The copper content in the low-copper high-ice nickel is 0.01 - 1.5 wt%, the nickel content is 50 - 85 wt%, and the cobalt content is 0.3 - 3 wt%. The method includes: Step S1, performing one-stage atmospheric pressure leaching and solid-liquid separation on the low-copper high-ice nickel to obtain a one-stage atmospheric pressure leaching solution and a first slag phase; Step S2, performing two-stage atmospheric pressure leaching and solid-liquid separation on the first slag phase to obtain a two-stage atmospheric pressure leaching solution and a second slag phase; Step S3, adjusting the pulp of the second slag phase and then performing one-stage oxygen pressure leaching to obtain a pulp; Then, performing solid-liquid separation on the pulp to obtain a total one-stage oxygen pressure leaching solution and a leaching residue; Step S4, performing copper removal treatment on at least one of the two-stage atmospheric pressure leaching solution and the total one-stage oxygen pressure leaching solution. Then, dividing the total one-stage oxygen pressure leaching solution into a first part of the one-stage oxygen pressure leaching solution and a second part of the one-stage oxygen pressure leaching solution, returning the first part of the one-stage oxygen pressure leaching solution and the two-stage atmospheric pressure leaching solution to Step S1 to participate in the one-stage atmospheric pressure leaching, and returning the second part of the one-stage oxygen pressure leaching solution to Step S2 to participate in the two-stage atmospheric pressure leaching.

[0021] The existing hydrometallurgical leaching process for high-ice nickel usually combines two-stage atmospheric pressure + two-stage pressure treatment. According to the material characteristics of the high-ice nickel to be processed, the present invention improves it to two-stage atmospheric pressure and one-stage pressure leaching, simplifying the process and saving costs. At the same time, the present invention also has the following advantages: By performing solid-liquid separation on the pulp obtained after two-stage atmospheric pressure leaching and adjusting the pulp of the second slag phase obtained after two-stage atmospheric pressure leaching, the leaching rates of nickel and cobalt are greatly increased; In one-stage oxygen pressure leaching, there is no need to consider inhibiting the leaching of copper, and only the leaching rates of nickel and cobalt need to be considered, so the reaction conditions are easy to control; By introducing a process for copper removal treatment, the problem of copper accumulation in the system is solved.

[0022] In actual operation, low-copper high-ice nickel is mostly obtained from laterite nickel ore. In addition to the above-mentioned copper, nickel, and cobalt, it may also contain the metal phase of nickel, the metal phase of cobalt, iron, the metal phase of iron, aluminum, and other inevitable impurities. In the present invention, unless otherwise specified, the "metal phase of a certain element" refers to the compound phase containing that element; the contents of the aforementioned copper, nickel, and cobalt are included in the content of that metal in their corresponding metal phases.

[0023] Specifically, during one-stage atmospheric pressure leaching, a nickel-cobalt solution with less impurities (i.e., one-stage atmospheric pressure leaching solution) is obtained, while copper, aluminum, iron, etc. remain in the slag phase; in two-stage atmospheric pressure leaching, the metal phases of nickel, cobalt, iron, etc. are deeply removed, enabling the second slag phase after two-stage atmospheric pressure leaching to safely enter the autoclave for one-stage oxygen pressure leaching; in one-stage oxygen pressure leaching, nickel and cobalt are further efficiently leached, and at the same time, iron is controlled in the leaching residue.

[0024] It should be emphasized that the present invention specifically provides copper removal treatment for at least one of the two-stage atmospheric pressure leaching solution and the total one-stage oxygen pressure leaching solution to reduce the circulation of copper elements in the system with the solution.

[0025] In a preferred embodiment, in low-copper high-ice nickel, the nickel content is 50-85 wt%, the nickel metal phase content is 40-50%, the iron content is 4-5.5%, the iron metal phase content is 2-3.5%, the cobalt content is 1-2.5 wt%, the cobalt metal phase content is 0.8-1.5%, the copper content is 0.1-0.5 wt%, and the aluminum content is 0.05-0.2%.

[0026] To better solve the problem of copper accumulation, in a preferred embodiment, the copper removal treatment is carried out using a reducing agent, the treatment temperature is 50 - 99 °C, and the time is 3 - 20 min; preferably, the dosage of the reducing agent is 0.2 - 10 times the weight of copper ions in the liquid phase; more preferably, the reducing agent is iron powder. Iron powder can provide a better reduction effect and has the advantages of less dosage and mild reaction conditions. In actual operation, technicians should provide a closed environment for this process flow to better improve the reaction rate. If it is impossible to provide a fully sealed environment due to on-site equipment limitations and air or oxygen is mixed in, the consumption of the reducing agent will increase. It should be noted that if the treatment temperature is too high or the time is too long, it may lead to increased energy consumption, more side reactions, and increased costs. If the temperature is too low or the time is too short, it may affect the copper removal efficiency, and may also lead to waste of resources, affect subsequent process steps, and prolong the production cycle.

[0027] In a preferred embodiment, in step S1, the first-stage atmospheric leaching includes: subjecting low-copper nickel matte to first-stage atmospheric leaching treatment using an oxidizing gas, sulfuric acid, second-stage atmospheric leaching solution, and a first part of the first-stage oxygen pressure leaching solution. Under the above conditions, the leaching rates of nickel and cobalt can be more effectively increased, while the dissolution of other impurity metals is reduced, ensuring the smooth progress of subsequent treatment steps and product quality.

[0028] To better improve the leaching effect of nickel and cobalt, in a preferred embodiment, in step S1, the temperature of the first-stage atmospheric leaching is 50 - 99 °C, the time is 3 - 20 h, the liquid-solid ratio is (4 - 15):1, and the final pH is 5.0 - 6.0. If the temperature of the first-stage atmospheric leaching is too high, it may accelerate the chemical reactions in the solution and even promote the dissolution of impurity metals (such as iron and aluminum), thus affecting the leaching selectivity and the efficiency of subsequent treatment steps; too low temperature may lead to a slow reaction rate, a decrease in the leaching rates of nickel and cobalt, and an extended leaching time. If the time of the first-stage atmospheric leaching is too long, it may lead to excessive leaching of nickel and cobalt, while increasing energy consumption and production costs; too short time may not fully leach nickel and cobalt, resulting in reduced leaching efficiency and output. If the liquid-solid ratio of the first-stage atmosphere is too high, it may increase the treatment cost, including the consumption of acid solution and other leaching agents, and may also reduce the leaching selectivity due to solution supersaturation; too low liquid-solid ratio may limit the contact area of reactants, affecting the reaction rate and the leaching efficiency of nickel and cobalt. If the final pH of the first-stage atmosphere is too high, it may lead to a decrease in the solubility of nickel and cobalt, affecting the leaching effect; too low pH value may promote the precipitation of sulfates, affecting the difficulty and cost of subsequent treatment.

[0029] In a preferred embodiment, the oxidizing gas is one or more of air, oxygen, and oxygen-rich gas, and the volume content of oxygen in the oxygen-rich gas is 35 - 60%.

[0030] In a preferred embodiment, in step S2, the two-stage atmospheric leaching includes: subjecting the first slag phase to two-stage atmospheric leaching treatment using an oxidizing gas, sulfuric acid, and the second part of the first-stage pressure leaching solution.

[0031] Under the above conditions, nickel and cobalt can be further efficiently leached, while preventing the dissolution of excessive impurity metals, creating more favorable conditions for subsequent pressure leaching and copper removal treatment.

[0032] Similarly, in order to better improve the effect of removing metal phases such as nickel, cobalt, and iron, in a preferred embodiment, in step S2, the temperature of the two-stage atmospheric leaching is 50-99 °C, the time is 3-20 h, the liquid-solid ratio is (4-15):1, and the final pH is 0.5-2.5; preferably, the oxidizing gas is one or more of air, oxygen, and oxygen-enriched gas, and the volume content of oxygen in the oxygen-enriched gas is 35-60%.

[0033] In a preferred embodiment, in step S3, the weight ratio of the first part of the first-stage pressure leaching solution to the second part of the first-stage pressure leaching solution is (1:3)-(3:1). Dividing the total first-stage pressure leaching solution into two parts and returning them to the previous steps according to the above ratio can further optimize resource utilization, improve the leaching rate of nickel and cobalt, and more effectively control the dissolution and accumulation of impurity metals, ensuring the efficiency and economy of the entire leaching process.

[0034] In order to better improve the effect of pressure leaching, in a preferred embodiment, in step S3, the temperature of the first-stage pressure leaching is 130-230 °C, the time is 1-10 h, the oxygen partial pressure is 0.05-2 MPa, and the liquid-solid ratio is (4-30):1. If the temperature of the first-stage pressure leaching is too high, it may accelerate the side reactions in the solution, causing oxidative losses of target metals such as nickel and cobalt, reducing their recovery rates, and increasing energy consumption and production costs; if too low, the reaction rate may slow down, affecting the leaching efficiency of nickel and cobalt and the production cycle. If the time of the first-stage pressure leaching is too long, it may lead to unnecessary energy consumption and increase production costs. At the same time, it may cause the metal ion concentration in the solution to be too high due to too long leaching time, affecting the efficiency of subsequent treatment steps; if too short, metals such as nickel and cobalt may not be completely dissolved, affecting the quality and output of the final product.

[0035] If the partial pressure of oxygen in a stage of oxygen pressure leaching is too high, it may increase the pressure load of the equipment, resulting in an increase in equipment costs. At the same time, it may accelerate equipment corrosion. If it is too low, it may not provide sufficient oxidation ability to promote the dissolution of metals, affecting the leaching efficiency. At the same time, it may lead to an overly slow reaction rate and an extended production cycle. If the liquid-solid ratio in a stage of oxygen pressure leaching is too high, it may cause waste of acid solution and other leaching agents, increasing unnecessary costs. At the same time, it may affect the dissolution rate and selectivity of metals due to the overly dilute solution. If it is too low, it may limit the contact area between reactants, affecting the reaction rate. At the same time, it may lead to solution concentration, which is not conducive to subsequent separation and treatment.

[0036] In a preferred embodiment, in step S4, through copper removal treatment, a crude copper product with a copper grade of 60-97% is obtained. In the above preferred embodiment, the present invention can obtain more products with added value.

[0037] In a preferred embodiment, in step S3, water is used for pulp mixing treatment. The process of pulp mixing is well-known to those skilled in the art and will not be elaborated here.

[0038] The following further describes the present application in detail with specific embodiments, which should not be construed as limiting the scope claimed by the present application.

[0039] Unless otherwise specifically explained, "%" all refers to "wt%".

[0040] Example 1

[0041] Taking a certain laterite nickel ore to produce nickel matte as the implementation object, the nickel content in the nickel matte is 71%, the nickel metal phase content is 45%, the iron content is 4.3%, the iron metal phase content is 2.1%, the cobalt content is 2.3%, the cobalt metal phase content is 1.09%, the copper content is 0.17%, and the aluminum content is 0.09%.

[0042] In step S1, using an oxidizing gas (air), sulfuric acid, the second-stage atmospheric leaching solution, and the first part of the first-stage oxygen pressure leaching solution, this nickel matte is subjected to the first-stage atmospheric leaching. The reaction temperature is 90 °C, air is introduced, the liquid-solid ratio is 8:1, the reaction time is 10 hours, the final pH value is controlled to be 5.7, and the acid-to-ore ratio is 200 Kg / t. Then, solid-liquid separation is carried out to obtain the first-stage atmospheric leaching solution and the first slag phase. The leaching rates of nickel and cobalt are 15% and 12% respectively. The concentrations of aluminum, iron, and copper ions in the first-stage atmospheric leaching solution are lower than 10 mg / L.

[0043] Step S2: Use an oxidizing gas (air), sulfuric acid, and the second part of the first-stage oxygen pressure leaching solution to perform second-stage atmospheric pressure leaching on the first slag phase. The reaction temperature is 90 °C, air is introduced, the liquid-solid ratio is 8:1, the reaction time is 10 hours, the final pH value is controlled at 1.1, and then solid-liquid separation is carried out to obtain the second-stage atmospheric pressure leaching solution and the second slag phase. After leaching, the leaching rates of nickel and cobalt are 51.9% and 60.2% respectively, the copper ion concentration in the leaching solution is 230 mg / L, and the iron ion concentration is 4501 mg / L. Return the second-stage atmospheric pressure leaching solution to the first-stage atmospheric pressure leaching step.

[0044] Step S3: Mix the second slag phase and water according to a mass ratio of 1:10, perform pulp preparation, enter the autoclave, the reaction temperature is 170 °C, the oxygen partial pressure is 0.4 MPa, the reaction time is 3 hours, and perform first-stage oxygen pressure leaching to obtain a pulp; then perform solid-liquid separation on the pulp to obtain the total first-stage oxygen pressure leaching solution and the leaching residue; divide the total first-stage oxygen pressure leaching solution into two parts, and the weight ratio of the first part of the first-stage oxygen pressure leaching solution to the second part of the first-stage oxygen pressure leaching solution is 1:1. Return the first part of the first-stage oxygen pressure leaching solution for first-stage atmospheric pressure leaching, and return the second part of the first-stage oxygen pressure leaching solution for second-stage atmospheric pressure leaching. The total leaching rates of nickel and cobalt are 99.5% and 98.7% respectively, the total copper leaching rate is 92.1%, the iron grade in the slag is 42%, and the iron into slag rate is 87%.

[0045] Among them, copper ions accumulate continuously in the system. When the copper ion concentration in the second-stage atmospheric pressure leaching solution accumulates to 4.5 g / L, use iron powder with a dosage 1 times that of the reduced copper ions to perform copper removal treatment at 75 °C for 10 min to obtain a crude copper product with a copper grade of 93.4%, and the copper removal rate is 70.1%.

[0046] Example 2

[0047] Perform hydrometallurgical leaching on the same nickel matte as in Example 1.

[0048] Step S1: Use an oxidizing gas (air), sulfuric acid, the second-stage atmospheric pressure leaching solution, and the first part of the first-stage oxygen pressure leaching solution to perform first-stage atmospheric pressure leaching on this nickel matte. The reaction temperature is 85 °C, air is introduced, the liquid-solid ratio is 8:1, the reaction time is 10 hours, the final pH value is controlled at 6.0, the acid-ore ratio is 200 Kg / t, and solid-liquid separation is carried out to obtain the first-stage atmospheric pressure leaching solution and the first slag phase. The leaching rates of nickel and cobalt are 16% and 11.3% respectively, and the concentrations of aluminum, iron, and copper ions in the first-stage atmospheric pressure leaching solution are less than 10 mg / L.

[0049] Step S2: Use oxidizing gas (air), sulfuric acid, and the second part of the first-stage oxygen pressure leaching solution to perform second-stage atmospheric pressure leaching on the first slag phase at a reaction temperature of 85°C, introduce air, with a liquid-solid ratio of 8:1, a reaction time of 8 hours, control the final pH value to be 1.3, then perform solid-liquid separation to obtain the second-stage atmospheric pressure leaching solution and the second slag phase; the removal rate of the metal phase exceeds 99%, and the leaching rates of nickel and cobalt after leaching are 50.1% and 59.4% respectively, the copper ion concentration in the leaching solution is 242 mg / L, and the iron ion concentration is 4301 mg / L. Return the second-stage atmospheric pressure leaching solution for first-stage atmospheric pressure leaching.

[0050] Step S3: Mix the second slag phase with water according to a mass ratio of 1:9 for pulp making, then enter the autoclave, with a reaction temperature of 180°C, an oxygen partial pressure of 0.3 MPa, and a reaction time of 5 hours for first-stage oxygen pressure leaching to obtain pulp; then perform solid-liquid separation on the pulp to obtain the total first-stage oxygen pressure leaching solution and the leaching residue; return the first part of the first-stage oxygen pressure leaching solution for first-stage atmospheric pressure leaching, and return the second part of the first-stage oxygen pressure leaching solution (the weight ratio of the first part of the first-stage oxygen pressure leaching solution to the second part of the first-stage oxygen pressure leaching solution is 1:3) for second-stage atmospheric pressure leaching. The total leaching rates of nickel and cobalt are 99.4% and 98.2% respectively, the total leaching rate of copper is 90.3%, the iron grade in the slag is 45%, and the iron into the slag rate is 89%.

[0051] Among them, copper ions continuously accumulate in the system. When the copper ion concentration in the second-stage atmospheric pressure leaching solution accumulates to 5 g / L, use iron powder with a dosage 1 time that of reducing the copper ions for copper removal, perform copper removal treatment at 99°C for 3 minutes to obtain a crude copper product with a copper grade of 90.4%, and the copper removal rate is 73.3%.

[0052] Example 3

[0053] Taking a certain laterite nickel ore to produce ferronickel as the implementation object, the nickel content in the ferronickel is 65%, the nickel metal phase content is 49%, the iron content is 5.3%, the iron metal phase content is 3.1%, the cobalt content is 1.3%, the cobalt metal phase content is 0.9%, the copper content is 0.21%, and the aluminum content is 0.13%.

[0054] Step S1: Use oxidizing gas (air), sulfuric acid, the second-stage atmospheric pressure leaching solution, and the first part of the first-stage oxygen pressure leaching solution to perform first-stage atmospheric pressure leaching on this ferronickel at a reaction temperature of 75°C, introduce air, with a liquid-solid ratio of 8:1, a reaction time of 10 hours, control the final pH value to be 5.8, and the acid-ore ratio to be 310 Kg / t, then perform solid-liquid separation to obtain the first-stage atmospheric pressure leaching solution and the first slag phase. The leaching rates of nickel and cobalt are 29% and 25% respectively, and the concentrations of aluminum, iron, and copper ions in the first-stage atmospheric pressure leaching solution are less than 10 mg / L.

[0055] Step S2: Using an oxidizing gas (air), sulfuric acid, and the second part of the first-stage oxygen pressure leaching solution, perform second-stage atmospheric pressure leaching on the first slag phase. The reaction temperature is 85°C, air is introduced, the liquid-solid ratio is 8:1, the reaction time is 10 hours, and the final pH value is controlled at 1.5. Then, perform solid-liquid separation to obtain the second-stage atmospheric pressure leaching solution and the second slag phase. After leaching, the leaching rates of nickel and cobalt are 45% and 53% respectively, the removal rate of the metal phase exceeds 99%, the copper ion concentration in the leaching solution is 242 mg / L, and the iron ion concentration is 4301 mg / L. Return the second-stage atmospheric pressure leaching solution for first-stage atmospheric pressure leaching.

[0056] Step S3: Mix the second slag phase and water according to a mass ratio of 1:9, perform pulp mixing, enter the autoclave, with a reaction temperature of 200°C, an oxygen partial pressure of 0.5 MPa, and a reaction time of 5 hours for first-stage oxygen pressure leaching to obtain pulp. Then, perform solid-liquid separation on the pulp to obtain the total first-stage oxygen pressure leaching solution and the leaching residue. Return the first part of the first-stage oxygen pressure leaching solution for first-stage atmospheric pressure leaching, and return the second part of the first-stage oxygen pressure leaching solution (the weight ratio of the first part of the first-stage oxygen pressure leaching solution to the second part of the first-stage oxygen pressure leaching solution is 3:1) for second-stage atmospheric pressure leaching. The total leaching rates of nickel and cobalt are 99.92% and 99.1% respectively, the total leaching rate of copper is 95.2%, the iron grade in the slag is 47.3%, and the iron into slag rate is 89%.

[0057] Copper ions continuously accumulate in the system. When the copper ion concentration in the second-stage atmospheric pressure leaching solution accumulates to 5 g / L, use iron powder with a dosage 1.2 times that of the reduced copper ions to remove copper. Perform copper removal treatment at 50°C for 20 minutes to obtain a crude copper product with a copper grade of 85.1% and a copper removal rate of 82.1%.

[0058] Example 4

[0059] The difference from Example 1 is that

[0060] For the first-stage atmospheric pressure leaching, the reaction temperature is 50°C, the liquid-solid ratio is 4:1, the final pH is 5.0, and the reaction time is 3 h.

[0061] For the second-stage atmospheric pressure leaching, the reaction temperature is 50°C, the liquid-solid ratio is 4:1, the final pH is 0.5, and the reaction time is 3 h.

[0062] For the first-stage oxygen pressure leaching, the temperature is 130°C, the time is 10 h, the oxygen partial pressure is 0.05 MPa, and the liquid-solid ratio is 4:1.

[0063] After leaching, together with the first-stage and second-stage atmospheric pressure leaching, the total leaching rates of nickel and cobalt are 98.3% and 95.9% respectively, the total leaching rate of copper is 93.6%, the iron grade in the slag is 50.3%, and the iron into slag rate is 93%.

[0064] Copper ions continuously accumulate in the system. When the concentration of copper ions in the total first-stage oxygen pressure leaching solution accumulates to 5.5 g / L, iron powder with a dosage 1.25 times that of the reduced copper ions is used for copper removal, obtaining a crude copper product with a copper grade of 91.3% and a copper removal rate of 87.2%.

[0065] Example 5

[0066] The difference from Example 4 is that

[0067] The temperature of the first-stage oxygen pressure leaching is 230 °C, the time is 1 h, the oxygen partial pressure is 2 MPa, and the liquid-solid ratio is 30:1.

[0068] After leaching, together with the first-stage and second-stage atmospheric pressure leaching, the total leaching rates of nickel and cobalt are 97.6% and 96.1% respectively, the total leaching rate of copper is 93.6%, the iron grade in the slag is 51.3%, and the iron entering the slag rate is 93.6%.

[0069] Copper ions continuously accumulate in the system. When the concentration of copper ions in the total first-stage oxygen pressure leaching solution accumulates to 5.5 g / L, iron powder with a dosage 9 times that of the reduced copper ions is used for copper removal, obtaining a crude copper product with a copper grade of 86.3% and a copper removal rate of 89.3%.

[0070] Comparative Example 1

[0071] The low-copper nickel matte of the present invention is processed using a conventional two-stage atmospheric pressure + two-stage oxygen pressure process.

[0072] It can be analyzed that compared with the two-stage atmospheric pressure + one-stage oxygen pressure process of the present application, this comparative example has one more oxygen pressure treatment process, increasing the process flow and equipment investment, and thus increasing the safety risk and production cost.

[0073] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0074] According to the material characteristics of the low-copper nickel matte to be processed, the present invention is improved to two-stage atmospheric pressure and one-stage pressure leaching, simplifying the process and saving costs. At the same time, the present invention also has the following advantages: by performing solid-liquid separation on the first pulp obtained after the second-stage atmospheric pressure leaching and adjusting the pulp of the second slag phase obtained after the second-stage atmospheric pressure leaching, the leaching rates of nickel and cobalt are greatly improved; in the first-stage oxygen pressure leaching, there is no need to consider suppressing the leaching of copper, and only the leaching rates of nickel and cobalt need to be considered, so the reaction conditions are easy to control; by introducing a copper removal treatment process, the problem of copper accumulation in the system is solved. Compared with the traditional process, the present invention provides a wet leaching method for low-copper nickel matte. It has low cost and high leaching rates of nickel and cobalt.

[0075] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A wet leaching method for low-copper nickel matte, wherein the copper content in the low-copper nickel matte is 0.01 - 1.5 wt%, the nickel content is 50 - 85 wt%, and the cobalt content is 0.3 - 3 wt%. It is characterized in that, The method includes: Step S1: subject the low - copper nickel matte to first - stage atmospheric leaching and solid - liquid separation to obtain a first - stage atmospheric leaching solution and a first slag phase; Step S2: subject the first slag phase to second - stage atmospheric leaching and solid - liquid separation to obtain a second - stage atmospheric leaching solution and a second slag phase; Step S3: after slurrying the second slag phase, conduct first - stage oxygen - pressure leaching to obtain a pulp; then conduct solid - liquid separation on the pulp to obtain a total first - stage oxygen - pressure leaching solution and a leaching residue; Step S4: conduct copper removal treatment on at least one of the second - stage atmospheric leaching solution and the total first - stage oxygen - pressure leaching solution. Then, divide the total first - stage oxygen - pressure leaching solution into a first - part first - stage oxygen - pressure leaching solution and a second - part first - stage oxygen - pressure leaching solution. Return the first - part first - stage oxygen - pressure leaching solution and the second - stage atmospheric leaching solution to Step S1 to participate in the first - stage atmospheric leaching, and return the second - part first - stage oxygen - pressure leaching solution to Step S2 to participate in the second - stage atmospheric leaching.

2. The low - copper nickel matte wet leaching method according to claim 1, wherein: The copper removal treatment is carried out using a reducing agent, the treatment temperature is 50 - 99 °C, and the time is 3 - 20 min; Preferably, the dosage of the reducing agent is 0.2 - 10 times the weight of copper ions in the liquid phase.

3. The low-copper nickel matte hydrometallurgical leaching method according to claim 1 or 2, characterized in that, In Step S1, The first - stage atmospheric leaching includes: subjecting the low - copper nickel matte to the first - stage atmospheric leaching treatment using an oxidizing gas, sulfuric acid, the second - stage atmospheric leaching solution, and the first - part first - stage oxygen - pressure leaching solution.

4. The low-copper high-ice-nickel hydrometallurgical leaching method according to claim 3, characterized in that, In Step S1, The temperature of the first - stage atmospheric leaching is 50 - 99 °C, the time is 3 - 20 h, the liquid - to - solid ratio is (4 - 15):1, and the end - point pH is 5.0 - 6.0; Preferably, the oxidizing gas is one or more of air, oxygen, and oxygen - rich gas, and the volume content of oxygen in the oxygen - rich gas is 35 - 60%.

5. The low-copper nickel matte hydrometallurgical leaching method according to any one of claims 1 to 4, characterized in that, In Step S2, The second - stage atmospheric leaching includes: subjecting the first slag phase to the second - stage atmospheric leaching treatment using an oxidizing gas, sulfuric acid, and the second - part first - stage oxygen - pressure leaching solution.

6. The wet leaching method of low-copper nickel matte according to claim 5, characterized in that, In Step S2, The temperature of the second - stage atmospheric leaching is 50 - 99 °C, the time is 3 - 20 h, the liquid - to - solid ratio is (4 - 15):1, and the end - point pH is 0.5 - 2.5; Preferably, the oxidizing gas is one or more of air, oxygen, and oxygen - rich gas, and the volume content of oxygen in the oxygen - rich gas is 35 - 60%.

7. The wet leaching method of low - copper nickel matte according to any one of claims 1 to 6, characterized in that, In Step S3, The weight ratio of the first - part first - stage oxygen - pressure leaching solution to the second - part first - stage oxygen - pressure leaching solution is (1:3) - (3:1).

8. The low-copper nickel matte hydrometallurgical leaching method according to any one of claims 1 to 7, characterized in that, In Step S3, The temperature of the first - stage oxygen - pressure leaching is 130 - 230 °C, the time is 1 - 10 h, the oxygen partial pressure is 0.05 - 2 MPa, and the liquid - to - solid ratio is (4 - 30):

1.

9. The low-copper matte nickel hydrometallurgical leaching method according to any one of claims 1 to 8, characterized in that, In Step S4, Through the copper removal treatment, a crude copper product with a copper grade of 60 - 97% is obtained.

10. The low - copper nickel matte wet leaching method according to any one of claims 1 to 9, wherein: In Step S3, water is used for the slurrying treatment.