A method for catalytic oxidation and stepwise precipitation of laterite nickel ore leaching solution

Abstract

This application provides a method for catalytic oxidation-stepwise precipitation of lateritic nickel ore leaching solution, relating to the field of hydrometallurgy. The method includes: adding a catalytic oxidant and a first neutralizing agent to the lateritic nickel ore leaching solution to obtain a first filtrate and iron slag; adding a catalytic oxidant, a second neutralizing agent, and a first agglomerating agent to the first filtrate to obtain a second filtrate and a second precipitate; adding a third neutralizing agent and a first reducing agent to the second filtrate to obtain a nickel-cobalt precipitate and a third filtrate; adding a fourth neutralizing agent and a second reducing agent to the third filtrate to obtain a fourth precipitate and a fourth filtrate; mixing the second precipitate with the third reducing agent and performing reduction leaching; adding a second agglomerating agent and a fifth neutralizing agent to obtain a silicon-aluminum precipitate and a manganese-scandium filtrate; extracting the manganese-scandium filtrate, with manganese entering the raffinate; adding a catalytic oxidant and a sixth neutralizing agent to the raffinate to obtain manganese oxide. This application enables stepwise element recovery, offering advantages such as recovering a wide variety of elements and minimizing resource waste.

Description

Technical Field

[0001] This application relates to the field of hydrometallurgy, and more particularly to a method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution. Background Technology

[0002] In recent years, with the rapid development of the energy industry, the demand for nickel and cobalt has been increasing, and laterite nickel ore has become one of the important raw materials for nickel and cobalt extraction. At present, the mainstream process for wet processing of laterite nickel ore is the high-pressure acid leaching process to prepare nickel and cobalt precipitate intermediates, namely: laterite nickel ore—ore beneficiation—high-pressure acid leaching—circulating leaching and pre-neutralization—CCD washing—iron and aluminum removal—nickel and cobalt precipitation to obtain nickel and cobalt intermediates. The leaching residue and iron and aluminum slag are washed by CCD and neutralized by tailings before being sent to deep-sea landfill or stored after pressure filtration.

[0003] Specifically, laterite nickel ore leaching solutions contain various elements such as iron, aluminum, manganese, magnesium, nickel, cobalt, scandium, and silicon. Currently, only nickel and cobalt are mainly recovered, while other elements are mostly removed as impurity ions and rarely recovered. The recovery of nickel and cobalt primarily involves first neutralizing and removing iron and aluminum using a two-stage calcium oxide process. After iron and aluminum removal, alkaline substances such as sodium hydroxide or magnesium hydroxide are added to the solution to precipitate nickel and cobalt, forming nickel-cobalt intermediates. After nickel and cobalt precipitation, limestone is used to neutralize and precipitate manganese and magnesium ions. The resulting iron-aluminum slag and manganese-magnesium slag are combined to form relatively stable tailings, which are then sent to deep-sea landfills or filtered and stockpiled. While this method can recover valuable nickel and cobalt from laterite nickel ore leaching solutions, other elements are mostly discharged as waste residue without being recycled, resulting in resource waste and environmental pollution. Summary of the Invention

[0004] The purpose of this application is to provide a method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution to solve the above-mentioned problems.

[0005] This application utilizes catalytic oxidation followed by stepwise precipitation to preferentially separate iron, manganese, aluminum, silicon, and scandium ions from the nickel-cobalt system in the form of iron slag and manganese-aluminum-silicon-scandium multi-element concentrates. The manganese-aluminum-silicon-scandium multi-element concentrates are then subjected to reducing acid dissolution to precipitate and remove silicon and aluminum impurities. Further scandium extraction and catalytic oxidation precipitation of manganese yield iron slag, silicon-aluminum precipitate, manganese oxide, and high-quality nickel-cobalt hydroxide, respectively. Scandium is then introduced into the extraction system, achieving stepwise precipitation and extraction of elements, improving the recovery rate of scandium and manganese, and realizing the comprehensive utilization of multiple elements.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] This application provides a method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution, comprising:

[0008] (1) Add a catalytic oxidant to the laterite nickel ore leaching solution, and add a first neutralizing agent to control the pH of the system, so that the Fe in the laterite nickel ore leaching solution is reduced. 2+ Complete catalytic oxidation and precipitation, followed by solid-liquid separation, yielded the first filtrate and iron slag.

[0009] (2) Add a catalytic oxidant, a second neutralizing agent and a first flocculant to the first filtrate, and control the pH of the system to reduce the concentration of Mn in the first filtrate. 2+ Complete catalytic oxidation simultaneously causes manganese, silicon, aluminum, and scandium ions to aggregate and co-precipitate. After solid-liquid separation, a second filtrate and a second precipitate are obtained.

[0010] (3) Add a third neutralizing agent and a first reducing agent to the second filtrate to adjust the pH of the solution to 6.7~7.1, so that the nickel and cobalt ions in the second filtrate precipitate. After solid-liquid separation, nickel and cobalt precipitate and third filtrate are obtained.

[0011] (4) Add a fourth neutralizing agent and a second reducing agent to the third filtrate, adjust the pH of the solution to 7.9~9.6, so that the nickel and cobalt ions in the third filtrate precipitate, and obtain a fourth precipitate and a fourth filtrate after solid-liquid separation; return the fourth precipitate to step (3) and mix it with the solution before the precipitation reaction in step (3);

[0012] (5) The second precipitate is mixed with the third reducing agent and reduced and leached under low acid conditions to leach manganese, aluminum, silicon, and scandium in the second precipitate. The second agglomerating agent and the fifth neutralizing agent are added to adjust the pH of the solution to 3.8~4.9 to precipitate silicon and aluminum ions. After solid-liquid separation, silicon and aluminum precipitate residue and manganese and scandium filtrate are obtained.

[0013] (6) Extract the manganese scandium filtrate so that scandium in the manganese scandium filtrate enters the extraction system and manganese in the manganese scandium filtrate enters the raffinate;

[0014] (7) Add a catalytic oxidant and a sixth neutralizing agent to the raffinate, control the pH of the system so that the manganese ions are completely catalytically oxidized to manganese oxide, and separate the solid and liquid to obtain manganese oxide precipitate residue and manganese-precipitated nickel-cobalt solution. The manganese-precipitated nickel-cobalt solution is returned to step (3) and mixed with the solution before the precipitation reaction in step (3).

[0015] According to embodiments of this application, the catalytic oxidant includes at least one of the following: a mixture of SO2 and air, flue gas containing sulfur dioxide, and a mixture of a solid additive capable of releasing SO2 and air. The solid additive includes one or more of metabisulfite, sulfite, bisulfite, and thiosulfate.

[0016] Furthermore, the volume of SO2 in the catalytic oxidant accounts for 0.42~4.2% of the total gas volume in the catalytic oxidant;

[0017] And / or, the reaction times of steps (1), (2), and (7) are the same or different, and are independently selected from 5 min to 600 min;

[0018] And / or, the reaction temperatures of steps (1), (2), and (7) are the same or different, and are independently selected from 5 to 99 °C.

[0019] Furthermore, in step (1), the addition of the catalytic oxidant makes the redox potential in step (1) 450mv-600mv;

[0020] And / or, in step (2), the addition of the catalytic oxidant makes the redox potential in step (2) higher than 600 mV;

[0021] And / or, in step (7), the addition of the catalytic oxidant makes the redox potential in step (7) higher than 600 mV.

[0022] Furthermore, in step (1), the addition of the first neutralizing agent controls the pH of the system in step (1) to be 2.7-3.2;

[0023] And / or, in step (2), the addition of the second neutralizing agent controls the pH of the system in step (2) to be 3.3-6.2.

[0024] And / or, in step (7), the addition of the sixth neutralizing agent controls the pH of the system in step (7) to be 3.7-5.6.

[0025] Furthermore, the first neutralizing agent includes at least one of calcium oxide, calcium hydroxide, calcium carbonate, calcium bicarbonate, magnesium oxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water;

[0026] The second, third, fourth, fifth, and sixth neutralizing agents independently include at least one of magnesium oxide, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia.

[0027] Furthermore, the first flocculant and the second flocculant independently include at least one of gelatin, guar gum, and plant gum.

[0028] Furthermore, in step (2), the mass of the first coalescing agent accounts for 0.02-20% of the total mass of the reaction system in step (2);

[0029] And / or, in step (5), the mass of the second coalescing agent accounts for 0.02-20% of the total mass of the reaction system in step (5).

[0030] Furthermore, the first reducing agent, the second reducing agent, and the third reducing agent independently include any one of sulfur dioxide, sodium metabisulfite, sodium sulfite, thiosulfate, and hydrogen.

[0031] Furthermore, the addition of the first reducing agent makes the redox potential in step (3) lower than 400mV;

[0032] And / or, the addition of the second reducing agent makes the redox potential in step (4) lower than 400 mV;

[0033] And / or, the addition of the third reducing agent makes the redox potential in step (5) lower than 350 mV;

[0034] Furthermore, in step (5), the low acid condition refers to a pH of 0.2-3.2.

[0035] Compared with the prior art, the beneficial effects of this application include:

[0036] 1. This application provides a method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution, which efficiently oxidizes iron and manganese ions step by step through catalytic oxidation, thereby achieving the precipitation and separation of iron and manganese.

[0037] 2. This application provides a method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution. By replacing the conventional two-stage neutralization and iron / aluminum removal process with a one-stage iron removal and two-stage multi-element centralized precipitation process, manganese, aluminum, silicon, and scandium ions in the solution are preferentially concentrated and co-precipitated, separating them from the nickel-cobalt smelting system in advance. This avoids manganese, silicon, aluminum, and scandium elements from entering the nickel-cobalt process, significantly reducing the content of impurities such as manganese, silicon, aluminum, and scandium in the nickel-cobalt hydroxide product. In addition, manganese and scandium with recycling value are separated from iron slag without recycling value in advance, improving the enrichment degree of scandium. This application has the technical advantages of advancing the impurity removal process, achieving a higher impurity removal rate, removing more types of impurities, and realizing centralized recovery of impurities.

[0038] 3. The method of catalytic oxidation-step precipitation of laterite nickel ore leaching solution provided in this application can make nickel and cobalt in the nickel-cobalt precipitate have all +2 valence by adding reducing agent and controlling atmosphere precipitation in two stages of step (3) and step (4), thus avoiding the formation of high-valence nickel and cobalt. In the subsequent acid dissolution refining process of nickel-cobalt precipitate, only acid needs to be added, and no reducing agent is required, which reduces the burden on subsequent nickel-cobalt refining.

[0039] 4. The present application provides a method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution, which oxidizes manganese into manganese oxide precipitate by catalytic oxidation of scandium extraction residue (extraction residue), thereby realizing the recovery of manganese ions.

[0040] 5. The present application provides a method for catalytic oxidation-step precipitation of laterite nickel ore leaching solution. By returning the manganese precipitation solution (sixth filtrate) to step (3) and mixing it with the solution before the precipitation reaction in step (3) to precipitate nickel and cobalt again, the recycling of nickel and cobalt ions is achieved, and the loss of nickel and cobalt is avoided.

[0041] In summary, the processing method of this application can achieve the separation and recovery of iron, silicon, aluminum, scandium, manganese, nickel and cobalt, recovering a wide variety of elements with minimal resource waste. Moreover, this application also has the advantages of thorough element separation, high enrichment rate, and low impurity content in nickel and cobalt hydroxide products. Attached Figure Description

[0042] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0043] Figure 1 This is a flowchart of the catalytic oxidation-step precipitation process of laterite nickel ore leaching solution in this application. Detailed Implementation

[0044] To better illustrate the technical solution provided in this application, the technical solution will be described in its entirety before the embodiments, as follows:

[0045] This application provides a method for treating laterite nickel ore leaching solution, including:

[0046] (1) Add a catalytic oxidant to the laterite nickel ore leaching solution, and add a first neutralizing agent to control the pH of the system, so that the Fe in the laterite nickel ore leaching solution is reduced. 2+ Complete catalytic oxidation and precipitation, followed by solid-liquid separation, yielded the first filtrate and iron slag.

[0047] (2) Add a catalytic oxidant, a second neutralizing agent and a first flocculant to the first filtrate, and control the pH of the system to reduce the concentration of Mn in the first filtrate. 2+ Complete catalytic oxidation simultaneously causes manganese, silicon, aluminum, and scandium ions to aggregate and co-precipitate. After solid-liquid separation, a second filtrate and a second precipitate are obtained.

[0048] (3) Add the third neutralizing agent and the first reducing agent to the second filtrate to adjust the pH of the solution to 6.7~7.1, so that the nickel and cobalt ions in the second filtrate precipitate. After solid-liquid separation, nickel and cobalt precipitate and the third filtrate are obtained.

[0049] (4) Add the fourth neutralizing agent and the second reducing agent to the third filtrate, adjust the pH of the solution to 7.9~9.6, so that the nickel and cobalt ions in the third filtrate precipitate. After solid-liquid separation, the fourth precipitate and the fourth filtrate are obtained. Return the fourth precipitate to step (3) and mix it with the solution before the precipitation reaction in step (3).

[0050] (5) Mix the second precipitate with the third reducing agent and reduce and leach under low acid conditions to leach manganese, aluminum, silicon, and scandium in the second precipitate. Add the second agglomerating agent and the fifth neutralizing agent to adjust the pH of the solution to 3.8~4.9 to precipitate silicon and aluminum ions. After solid-liquid separation, obtain silicon and aluminum precipitate residue and manganese and scandium filtrate.

[0051] (6) Extract the manganese scandium filtrate so that scandium in the manganese scandium filtrate enters the extraction system and manganese in the manganese scandium filtrate enters the raffinate;

[0052] (7) Add a catalytic oxidant and a sixth neutralizing agent to the raffinate, control the pH of the system so that the manganese ions are completely catalytically oxidized to manganese oxides, and separate the solid and liquid to obtain manganese oxide precipitate residue and manganese-precipitated nickel-cobalt solution. The manganese-precipitated nickel-cobalt solution is returned to step (3) and mixed with the solution before the precipitation reaction in step (3).

[0053] This application enables the separation of iron through step (1), the transfer and precipitation of manganese through steps (2) and (7), and the preparation of nickel-cobalt precipitates with low impurity content through steps (3) and (4). Scandium can be enriched and separated through step (6), and silicon-aluminum can be separated through directional aggregation through step (5). In summary, the processing method of this application can obtain various materials such as iron slag, silicon-aluminum precipitates, manganese oxides, and nickel-cobalt precipitates, and allows scandium to enter the extraction system, achieving the separation and enrichment of multiple elements including iron, manganese, nickel-cobalt, scandium, and silicon-aluminum.

[0054] Specifically, both steps (3) and (4) aim to precipitate nickel-cobalt ions. The difference is that the pH in step (3) is lower than that in step (4). Under lower pH conditions, the nickel-cobalt precipitate formed has a lower impurity content. Higher pH conditions allow residual nickel-cobalt ions in the solution to be transferred more fully to the precipitate, but higher pH results in a higher impurity content in the precipitate. This application employs a stepwise precipitation method and transfers the fourth precipitate formed under high pH conditions to step (3) for reprocessing. This method is beneficial for obtaining a nickel-cobalt precipitate with low impurity content and allows for control of crystal particle size during the precipitation process.

[0055] According to embodiments of this application, the catalytic oxidant includes at least one of the following: a mixture of SO2 and air, flue gas containing sulfur dioxide, and a mixture of a solid additive capable of releasing SO2 and air. The solid additive includes one or more of metabisulfite, sulfite, bisulfite, and thiosulfate.

[0056] Furthermore, metabisulfites include, but are not limited to, sodium metabisulfite; sulfites include, but are not limited to, sodium sulfite; bisulfites include, but are not limited to, sodium bisulfite; and thiosulfates include, but are not limited to, sodium thiosulfate.

[0057] The volume of SO2 in the catalytic oxidant accounts for 0.42-4.2% of the total gas volume in the catalytic oxidant; when the above conditions are met, the catalytic oxidant has a high oxidation effect. If the above catalytic oxidant is not added, a more stringent pH requirement is required, and the formed precipitate is prone to contain more impurities. This application, by adding the above catalytic oxidant, can oxidize metal ions, and the oxidized metal ions can form a precipitate with fewer impurities under relatively mild pH conditions.

[0058] For example, in the catalytic oxidant, the volume of SO2 accounts for 0.42%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, or 4.2% of the total gas volume in the catalytic oxidant.

[0059] Specifically, the addition of a catalytic oxidant in step (1) is beneficial to the Fe in the laterite nickel ore leaching solution. 2+ Oxidized to Fe 3+ This allows for the separation of iron ions under relatively mild pH conditions. Adding a catalytic oxidant in step (2) facilitates the separation of Mn from the first filtrate. 2+ Oxidation facilitates the formation of manganese precipitate under milder conditions. Adding a catalytic oxidant in step (7) helps to oxidize manganese ions in the raffinate and reduces the pH requirement for manganese ion precipitation.

[0060] And / or, the reaction times of steps (1), (2), and (7) are the same or different, and are independently selected from 5 min to 600 min;

[0061] For example, the reaction time for steps (1), (2), and (7) can be 5 min, 30 min, 60 min, 90 min, 120 min, 150 min, 180 min, 210 min, 240 min, 270 min, 300 min, 330 min, 360 min, 390 min, 420 min, 450 min, 480 min, 510 min, 540 min, 570 min, or 600 min.

[0062] And / or, the reaction temperatures of steps (1), (2), and (7) are the same or different, and are independently selected from 5 to 99 °C.

[0063] For example, the reaction temperatures in steps (1), (2), and (7) can be 5℃, 10℃, 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, and 99℃.

[0064] According to an embodiment of this application, in step (1), the addition of the catalytic oxidant makes the redox potential in step (1) 450mv-600mv;

[0065] And / or, in step (2), the addition of the catalytic oxidant makes the redox potential in step (2) higher than 600 mV;

[0066] And / or, in step (7), the addition of the catalytic oxidant makes the redox potential in step (7) higher than 600 mV.

[0067] According to an embodiment of this application, the addition of the first neutralizing agent controls the pH of the system in step (1) to be 2.7-3.2;

[0068] And / or, in step (2), the addition of the second neutralizing agent controls the pH of the system in step (2) to be 3.3-6.2;

[0069] And / or, in step (7), the addition of the sixth neutralizing agent controls the pH of the system in step (7) to be 3.7-5.6.

[0070] According to an embodiment of this application, the first neutralizing agent includes at least one of calcium oxide, calcium hydroxide, calcium carbonate, calcium bicarbonate, magnesium oxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water.

[0071] The second, third, fourth, fifth, and sixth neutralizing agents independently include at least one of magnesium oxide, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia.

[0072] The first, second, third, fourth, fifth, and sixth neutralizing agents are used to adjust the pH value of the solution. This application allows for adjustment of the pH value of the solution by varying the dosage of different neutralizing agents, ensuring that the pH value meets the precipitation pH requirements of different metal ions, thus enabling the separation of elements such as iron, nickel, cobalt, manganese, silicon, aluminum, and scandium from laterite nickel ore leaching solutions.

[0073] According to embodiments of this application, the first coalescing agent and the second coalescing agent independently comprise at least one of gelatin, guar gum, and plant gum.

[0074] According to an embodiment of this application, in step (2), the mass of the first coalescing agent accounts for 0.02-20% of the total mass of the reaction system in step (2);

[0075] And / or, in step (5), the mass of the second coalescing agent accounts for 0.02-20% of the total mass of the reaction system in step (5).

[0076] According to embodiments of this application, the first reducing agent, the second reducing agent, and the third reducing agent independently include any one of sulfur dioxide, sodium metabisulfite, sodium sulfite, thiosulfate, and hydrogen.

[0077] According to an embodiment of this application, the addition of the first reducing agent makes the redox potential in step (3) lower than 400mV;

[0078] The addition of the first reducing agent can avoid Ni in step (3). 2+ and Co 2+ Oxidized to Ni 3+ and Co 3+ This is beneficial to Ni 2+ and Co 2+ It is converted into Ni(OH)2 and Co(OH)2. The nickel-cobalt hydroxide precipitate obtained in step (3) has a low content of manganese, magnesium and silicon impurities.

[0079] And / or, the addition of a second reducing agent makes the redox potential in step (4) lower than 400 mV;

[0080] The addition of the second reducing agent can avoid Ni in step (4). 2+ and Co 2+ Oxidized to Ni 3+ and Co 3+ This, in turn, facilitates the removal of residual Ni 2+ and Co 2+ It is converted into Ni(OH)2 and Co(OH)2.

[0081] Furthermore, the fourth filtrate contains magnesium ions. The fourth filtrate can be transferred to the water treatment process.

[0082] And / or, the addition of a third reducing agent makes the redox potential in step (5) lower than 350 mV;

[0083] According to an embodiment of this application, in step (5), the low acid condition refers to a pH of 0.2-3.2.

[0084] According to an embodiment of this application, in step (6), the extraction of the manganese scandium filtrate includes continuous extraction; further, continuous extraction includes countercurrent extraction.

[0085] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0086] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0087] Example 1

[0088] like Figure 1 As shown, this embodiment provides a method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution, specifically including the following steps:

[0089] (1) Elemental analysis was performed on 2L of acid leaching solution of laterite nickel ore from smelting enterprises in Indonesia. The composition is shown in Table 1.

[0090] Table 1. Composition of laterite nickel ore leaching solution

[0091]

[0092] A mixture of SO2 and air, comprising 2% SO2 by volume, was introduced into the leaching solution of the aforementioned laterite nickel ore, and 20% calcium oxide emulsion was added to maintain the pH at 2.8 for Fe. 2+ Catalytic oxidation was carried out. After the system potential reached 450mv or higher, calcium oxide emulsion was added to control the pH to 3.1 for iron ion precipitation. The resulting slurry was filtered to obtain precipitate (iron slag) and first filtrate. The content of each component in the first filtrate was analyzed, as shown in Table 2. As can be seen from Table 2, the iron removal rate in step (1) reached more than 99%, and the residual iron content in the solution was 0.08mg / L.

[0093] Table 2 Composition of the first filtrate

[0094]

[0095] (2) Continue to pass a mixture of SO2 and air with a volume ratio of 2% SO2 into the first filtrate to make the redox potential in this step higher than 610 mV; and add 10% sodium carbonate solution to maintain the pH at 5.1 relative to Mn. 2+ Catalytic oxidation was carried out for 6 hours, and then 10% sodium carbonate solution was added to the solution to control the pH to 6.1. 1g of gelatin (the mass of the added gelatin accounts for 0.05% of the total mass of the material in step (2)) was added to carry out agglomeration and precipitation. The resulting slurry was filtered to obtain the second precipitate and the second filtrate. The content of each component in the second filtrate was analyzed and shown in Table 3. As can be seen from Table 3, the removal rate of manganese in step (2) was 99.83%, the removal rate of silicon was 99.85%, the removal rate of aluminum was 99.80%, and the removal rate of scandium was 99.27%.

[0096] Table 3. Composition of the second filtrate

[0097]

[0098] (3) Sulfur dioxide gas is introduced into the second filtrate to make the redox potential in this step lower than 400 mV, and 10% sodium carbonate is added to control the pH to 6.7, so that Ni 2+ and Co 2+ The precipitates are Ni(OH)2 and Co(OH)2. After reacting for 2 hours, the resulting slurry is filtered to obtain nickel-cobalt precipitates and a third filtrate. The content of each component in the third filtrate is analyzed, as shown in Table 4. As can be seen from Table 4, the nickel precipitation rate in step (3) is 50.05%, and the cobalt precipitation rate is 49.50%.

[0099] Table 4. Composition of the third filtrate

[0100]

[0101] Table 5. Composition of Nickel-Cobalt Precipitates

[0102]

[0103] Valence state analysis of nickel and cobalt in nickel-cobalt precipitates showed that the content of +3 valent nickel in the precipitates was less than 0.04%, and the content of +3 valent cobalt in the precipitates was less than 0.05%.

[0104] (4) Sulfur dioxide gas is introduced into the third filtrate to make the redox potential in this step lower than 400mV, and 10% sodium carbonate is added to control the pH to 9.4, so as to remove the residual Ni. 2+ and Co 2+The precipitate is converted into Ni(OH)2 and Co(OH)2. The resulting slurry is filtered to obtain a fourth precipitate and a fourth filtrate. The fourth precipitate is mixed with the solution before the precipitation reaction in step (3), and the fourth filtrate is sent to the water treatment process. The content of each component in the fourth filtrate is analyzed, as shown in Table 6. As can be seen from Table 6, the final precipitation rate of nickel in step (4) is 99.64%, and the precipitation rate of cobalt is 99.22%.

[0105] Table 6 Composition of the fourth filtrate

[0106]

[0107] (5) The second precipitate was mixed with water to form a slurry, and sulfur dioxide gas was introduced to make the redox potential in this step lower than 350 mV; reduction leaching was carried out under low acid conditions of pH=0.2. After complete leaching, 15 g of gelatin (the mass of the added gelatin accounts for 0.75% of the total mass of the material in step (5)) and 10% sodium carbonate were added, and the pH was slowly adjusted to 4.8 to agglomerate and precipitate silicon and aluminum, obtaining silicon and aluminum precipitate and manganese scandium filtrate. After drying, the silicon and aluminum precipitate was analyzed to have a silicon content of 26.23%.

[0108] (6) The manganese-scandium filtrate is sent to a multi-stage continuous countercurrent extraction system for scandium recovery. Scandium in the solution is extracted and recovered, while manganese in the solution is not extracted and remains in the raffinate.

[0109] (7) A mixture of SO2 and air with a volume ratio of 2% SO2 is introduced into the raffinate to make the redox potential in this step higher than 650mV; and 10% sodium carbonate is added to maintain the pH at 5.6 relative to Mn. 2+ Catalytic oxidation was performed to obtain manganese oxide and the sixth filtrate. The manganese content in the sixth filtrate was 0.24 mg / L, and the manganese content in the manganese oxide was 43.22%. The sixth filtrate was mixed with the solution before the precipitation reaction in step (3) to return the nickel and cobalt ions in the solution to the precipitate.

[0110] Example 2

[0111] like Figure 1 As shown, this embodiment provides a method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution, specifically including the following steps:

[0112] Lateritic nickel ore provided by a mine in Southeast Asia was crushed, finely ground, and then subjected to high-pressure acid leaching to obtain lateritic nickel ore leachate, the composition of which is shown in Table 7.

[0113] Table 7 Composition of Laterite Nickel Ore Leachate

[0114]

[0115] The above-mentioned laterite nickel ore leaching solution was pumped into a stirred tank. Sodium metabisulfite solution and air were injected into the tank, with the flow rates controlled to ensure that the volume of released SO2 accounted for 1.45% of the total volume of released SO2 and air. Then, 10% limestone emulsion was added, and the pH was controlled at 2.7-3.0 to adjust the Fe... 2+ After catalytic oxidation, when the system potential reaches 520mv or higher, limestone emulsion is added to control the pH to 3.2 for iron ion precipitation. The resulting slurry is separated into solid and liquid components using a filter press to obtain precipitate (iron slag) and first filtrate. The content of each component in the first filtrate is analyzed, as shown in Table 8. As can be seen from Table 8, the iron removal rate in step (1) reaches 99.65%, and the residual iron content in the solution is 0.023g / L.

[0116] Table 8 Composition of the first filtrate

[0117]

[0118] (2) Pump the first filtrate into a stirred tank, inject sodium metabisulfite solution and air into the tank, control the flow rate of sodium metabisulfite solution and air to make the volume of released SO2 account for 1.45% of the total volume of released SO2 and air, add 10% lime slurry to maintain pH at 4.5, and after the redox potential in this step reaches 700mV, perform catalytic oxidation for 3h, then add 10% lime slurry to control pH to reach 6.2, and add guar gum to perform agglomeration and precipitation, the amount of guar gum added is 0.5g / L. -溶液 (The mass of the added guar gum accounts for 0.05% of the total mass of the material in step (2)). The obtained slurry is subjected to solid-liquid separation using a filter press to obtain the second precipitate and the second filtrate. The content of each component in the second filtrate is analyzed, as shown in Table 9. As can be seen from Table 9, the manganese removal rate in step (2) is 98.19%, the silicon removal rate is 90.20%, the aluminum removal rate is 99.34%, and the scandium removal rate is 99.94%.

[0119] Table 9 Composition of the second filtrate

[0120]

[0121] (3) Pump the second filtrate into a stirred tank and add sodium metabisulfite solution dropwise, controlling the amount added to keep the redox potential below 380 mV in this step, thus suppressing Ni 2+ and Co 2+The oxidation was carried out, and 10% sodium hydroxide solution was added to control the pH to 6.9, so that nickel and cobalt ions were precipitated in the form of divalent, i.e., Ni(OH)2 and Co(OH)2 were formed. After the reaction was carried out for 4 hours, the slurry was separated into solid and liquid by a filter press to obtain nickel and cobalt precipitate and third filtrate. The content of each component in the third filtrate was analyzed, as shown in Table 10. As can be seen from Table 10, the nickel precipitation rate in step (3) was 44.33%, and the cobalt precipitation rate was 52.94%.

[0122] Table 10 Composition of the Third Filtrate

[0123]

[0124] (4) Pump the third filtrate into a stirred tank, add sodium metabisulfite solution dropwise, and control the amount added so that the redox potential in this step is below 380mV to suppress Ni 2+ and Co 2+ The oxidation was carried out, and a 10% sodium hydroxide solution was added to control the pH to 9.5, thus removing the residual Ni. 2+ and Co 2+ All the precipitate was converted into Ni(OH)2 and Co(OH)2. The resulting slurry was subjected to solid-liquid separation using a filter press to obtain the fourth precipitate and the fourth filtrate. The fourth precipitate was mixed with the solution before the precipitation reaction in step (3), and the fourth filtrate was sent to the magnesium recovery process. The content of each component in the fourth filtrate was analyzed, as shown in Table 11. As can be seen from Table 11, the final precipitation rate of nickel in step (4) was 99.91%, and the precipitation rate of cobalt was 97.06%.

[0125] Table 11 Composition of the fourth filtrate

[0126]

[0127] (5) Mix the second precipitate with water to form a slurry, add sodium metabisulfite solution dropwise to make the redox potential in this step lower than 300mv; carry out reduction leaching under low acid conditions of pH=0.4. After complete leaching, add 24g of guar gum (the mass of the added guar gum accounts for 0.05% of the total mass of the material in step (5)) and 10% limestone emulsion and slowly adjust the pH to 4.9 to carry out agglomeration and precipitation of silica and aluminum. Use a filter press to separate the solid and liquid of the obtained slurry to obtain silica and aluminum precipitate and manganese scandium filtrate. The silica removal rate reaches 95.53% and the aluminum removal rate is 98.46%.

[0128] (6) The manganese-scandium filtrate is sent to a multi-stage continuous countercurrent extraction system for scandium recovery. Scandium in the solution is extracted and recovered, while manganese in the solution is not extracted and remains in the raffinate.

[0129] (7) Inject sodium metabisulfite solution and air into the raffinate, controlling the flow rate of the sodium metabisulfite solution and air to ensure that the volume of released SO2 accounts for 1.45% of the total volume of released SO2 and air. Add 10% sodium carbonate to maintain the pH at 5.6, so that the redox potential in this step is higher than 710 mV, which is beneficial to Mn. 2+ Catalytic oxidation precipitation was carried out, and the obtained slurry was separated into solid and liquid by a filter press to obtain manganese oxide and sixth filtrate. The manganese content in the sixth filtrate was 0.17 mg / L, and the manganese content in the manganese oxide was 33.42%. The sixth filtrate was mixed with the solution before the precipitation reaction in step (3), and the nickel and cobalt ions in the solution were returned to the precipitate of nickel and cobalt.

[0130] Example 3

[0131] This embodiment provides a method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution, with the same raw materials as in Example 1, and the composition is shown in Table 12.

[0132] Table 12 Composition of Laterite Nickel Ore Leachate

[0133]

[0134] (1) Pump the above solution into a cubic reaction vessel, introduce flue gas containing sulfur dioxide into the vessel, the volume of SO2 in the flue gas accounting for 2.4% of the total volume of the flue gas, and then add 10% of highly active magnesium oxide emulsion, controlling the pH to 2.8 for Fe 2+ Catalytic oxidation was carried out, and after the system potential reached above 500mv, the pH was adjusted to 3.2 to precipitate iron ions. The slurry was filtered to obtain precipitate (iron slag) and first filtrate. The content of each component in the first filtrate was sampled and analyzed, as shown in Table 13. As can be seen from Table 13, the iron content in the solution of step (1) decreased from 3431mg / L to 4.2mg / L, and the iron removal rate reached 99.88%.

[0135] Table 13 Composition of the first filtrate

[0136]

[0137] (2) The first filtrate was pumped into a cubic reaction tank, and flue gas containing sulfur dioxide was introduced into the tank. The volume of SO2 in the flue gas accounted for 2.4% of the total volume of the flue gas. 10% magnesium oxide emulsion was added to maintain the pH at 5.3. After the redox potential in this step reached 620 mV, catalytic oxidation was carried out for 4 hours. Then, 10% lime slurry was added to control the pH to reach 6.2, and guar gum was added to carry out agglomeration and precipitation. The amount of guar gum added was 0.25 g / L. -溶液(The mass of the added guar gum accounts for 0.025% of the total mass of the material in step (2)). The obtained slurry is separated into solid and liquid by a filter press to obtain the second precipitate and the second filtrate. The contents of each component in the second filtrate are analyzed by sampling, as shown in Table 14. As can be seen from Table 14, the manganese removal rate in step (2) is 98.29%, the silicon removal rate is 98.63%, the aluminum removal rate is 99.67%, and the scandium removal rate is 98.09%.

[0138] Table 14 Composition of the Second Filtrate

[0139]

[0140] (3) Pump the second filtrate into a cubic reaction vessel, introduce SO2 gas into the vessel to remove oxidizing substances from the reaction vessel, control the introduction rate to keep the redox potential below 340 mV in this step, and suppress Ni 2+ and Co 2+ The oxidation was carried out, and 20% sodium carbonate solution was added to control the pH to 7.0, so that nickel and cobalt ions were precipitated in the form of divalent, i.e., Ni(OH)2 and Co(OH)2 were formed. After the reaction was carried out for 2 hours, the slurry was separated into solid and liquid by a filter press to obtain nickel and cobalt precipitate and third filtrate. The content of each component in the third filtrate was analyzed by sampling, as shown in Table 15. As can be seen from Table 15, the nickel precipitation rate in step (3) was 63.40%, and the cobalt precipitation rate was 60.57%.

[0141] Table 15 Composition of the Third Filtrate

[0142]

[0143] Table 16 Composition Table of Nickel-Cobalt Hydroxide Products

[0144]

[0145] (4) Pump the third filtrate into a cubic reaction vessel, introduce SO2 gas into the vessel to remove oxidizing substances, and control the introduction rate to keep the redox potential below 340 mV in this step to suppress Ni 2+ and Co 2+ The oxidation was carried out, and a 20% sodium carbonate solution was added to control the pH to 9.6, thus removing the residual Ni. 2+ and Co 2+ All the precipitate was converted into Ni(OH)2 and Co(OH)2. The resulting slurry was subjected to solid-liquid separation using a filter press to obtain the fourth precipitate and the fourth filtrate. The fourth precipitate was mixed with the solution before the precipitation reaction in step (3), and the fourth filtrate was sent to the magnesium recovery process. The content of each component in the fourth filtrate was analyzed by sampling, as shown in Table 17. As can be seen from Table 17, the nickel precipitation rate in step (4) was 99.57%, and the cobalt precipitation rate was 99.57%.

[0146] Table 17 Composition of the fourth filtrate

[0147]

[0148] (5) The second precipitate is mixed with water to form a slurry. Flue gas containing sulfur dioxide is introduced into the tank to make the redox potential in this step lower than 320 mV. Reduction leaching is carried out under low acid conditions of pH=1.2. After complete leaching, guar gum is added to promote agglomeration and precipitation. The amount of guar gum added is 2.5 g / L. -溶液 (The mass of the added guar gum accounts for 0.25% of the total mass of the material in step (5)). 10% limestone emulsion is added and the pH is slowly adjusted to 4.9 to agglomerate and precipitate silicon and aluminum. The resulting slurry is separated into solid and liquid by a filter press to obtain silicon and aluminum precipitate and manganese and scandium filtrate. The silicon removal rate reaches 96.23% and the aluminum removal rate is 97.35%.

[0149] (6) The manganese-scandium filtrate is sent to a multi-stage continuous countercurrent extraction system for scandium recovery. Scandium in the solution is extracted and recovered, while manganese in the solution is not extracted and remains in the raffinate.

[0150] (7) Flue gas containing sulfur dioxide is introduced into the raffinate. The volume of SO2 in the flue gas accounts for 2.4% of the total volume of the flue gas. 10% sodium carbonate is added to maintain the pH at 5.4, so that the redox potential in this step is higher than 680mV, which is beneficial to Mn. 2+ Catalytic oxidation precipitation was carried out, and the obtained slurry was separated into solid and liquid by a filter press to obtain manganese oxide and sixth filtrate. The manganese content in the sixth filtrate was 1.2 mg / L, and the manganese content in the manganese oxide was 34.68%. The sixth filtrate was mixed with the solution before the precipitation reaction in step (3), and the nickel and cobalt ions in the solution were returned to the precipitate of nickel and cobalt.

[0151] Comparative Example 1

[0152] This comparative example provides a method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution. The difference from Example 1 is that the volume of SO2 in steps (1), (2), and (7) accounts for 18% of the volume of the SO2 and air mixture. After the reaction, the iron content in the first filtrate was 3412 mg / L and the manganese content in the second filtrate was 3104 mg / L.

[0153] In Comparative Example 1, the volume of SO2 in the SO2-air mixture was too large, failing to catalytically oxidize and remove the iron and manganese ions.

[0154] Comparative Example 2

[0155] This comparative example provides a method for catalytic oxidation-step precipitation of laterite nickel ore leaching solution. The difference from Example 1 is that oxygen is introduced in steps (1), (2) and (7). After the reaction is completed, the iron content in the first filtrate is 143 mg / L and the manganese content in the second filtrate is 3078 mg / L.

[0156] Comparative Example 2 did not use the type of catalytic oxidant specified in this application. After step (2), it failed to catalytically oxidize manganese ions and remove them.

[0157] Comparative Example 3

[0158] This comparative example provides a method for catalytic oxidation-step precipitation of laterite nickel ore leaching solution. The difference from Example 1 is that in step (2), the pH is adjusted to 3.0 and the first agglomerating agent gelatin is not added. After the reaction is completed, the second filtrate is sampled and analyzed to find that the silicon content is 100.23 mg / L, the aluminum content is 3486 mg / L, and the manganese content is 3076 mg / L.

[0159] In Comparative Example 3, the pH of step (2) was not controlled as required, and the first coalescing agent was not added. After step (2) was completed, the silicon, aluminum and manganese ions in the solution were not removed from the nickel-cobalt system. These ions were transferred into the nickel-cobalt precipitate, which increased the impurity content in the nickel-cobalt hydroxide product.

[0160] Comparative Example 4

[0161] This comparative example provides a method for catalytic oxidation-stepwise precipitation of lateritic nickel ore leaching solution. The difference from Example 1 is that: in step (3), no first reducing agent was added; in step (4), no second reducing agent was added to control the system potential. After the reaction, the valence states of nickel and cobalt in the fourth precipitate obtained in step (4) were analyzed. The Ni content in the nickel-cobalt hydroxide product... 3+ The content is 2.3%, Co 3+ The content is 3.5%.

[0162] In Comparative Example 4, no first reducing agent was added in step (3) and no second reducing agent was added in step (4). That is, the system potential was not controlled in steps (3) and (4) of Comparative Example 4. After step (4) was completed, some nickel and cobalt precipitated in the +3 valence, and the nickel and cobalt in the nickel hydroxide product were not controlled to be all in the +2 valence.

[0163] Comparative Example 5

[0164] This comparative example provides a method for catalytic oxidation-step precipitation of laterite nickel ore leaching solution. The difference from Example 1 is that in step (1), the pH is directly adjusted to 6.0. During the reaction process, the solution becomes slurry and gelled, making it difficult to settle and filter.

[0165] In Comparative Example 5, the pH was too high in step (1). After step (1) was completed, iron, manganese, silicon, aluminum, scandium and other elements precipitated together, forming a variety of colloidal substances such as iron hydroxide colloid, aluminum hydroxide colloid, and silica gel. The solid-liquid separation was extremely difficult, and the stepwise extraction of elements could not be achieved.

[0166] Comparative Example 6

[0167] This comparative example provides a method for catalytic oxidation-step precipitation of laterite nickel ore leaching solution. The difference from Example 1 is that: in step (5), the second agglomerating agent gelatin was not added, and the pH was directly adjusted to 4.9. After the reaction was completed, the silicon content in the solution was 90.43 mg / L, which is relatively high. The silicon was not removed, and the slurry was difficult to filter.

[0168] Comparative Example 6 did not add the second agglomerating agent gelatin in step (5); after step (5) was completed, silicon failed to precipitate with aluminum, and the formed aluminum hydroxide did not agglomerate, making solid-liquid separation extremely difficult and causing difficulties for the subsequent recovery of scandium and manganese.

[0169] Comparative Example 7

[0170] This comparative example provides a method for catalytic oxidation-step precipitation of laterite nickel ore leaching solution. The difference from Example 1 is that sulfur dioxide gas, a reducing agent, was not added in step (5). That is, the system potential was not controlled in step (5) of Comparative Example 7. After acid leaching, a large amount of solid residue remained undissolved, and the scandium leaching rate was only 28.33% and the manganese leaching rate was 19.86%.

[0171] In step (5) of the comparative example, sulfur dioxide gas, a reducing agent, was not added to control the system potential; scandium and manganese failed to dissolve efficiently, and the recovery and utilization of scandium and manganese were not achieved.

[0172] Comparative Example 8

[0173] This comparative example provides a method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution. The difference from Example 1 is that the sixth filtrate in step (7) is not returned to the solution before the precipitation reaction in step (3) for mixing, but is directly discharged or input into other processes, causing resource waste and pollution problems, and disrupting the element flow of the process. Analysis of the sixth filtrate revealed a nickel content of 0.57 g / L and a cobalt content of 0.24 g / L.

[0174] In Comparative Example 8, the sixth filtrate in step (7) was not returned to step (3), and the nickel and cobalt ions in the sixth filtrate could not be recovered, resulting in a waste of resources.

[0175] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0176] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution, characterized in that, include: (1) Add a catalytic oxidant to the laterite nickel ore leaching solution, and add a first neutralizing agent to control the pH of the system, so that the Fe in the laterite nickel ore leaching solution is reduced. 2+ Complete catalytic oxidation and precipitation, followed by solid-liquid separation, yielded the first filtrate and iron slag. (2) Add a catalytic oxidant, a second neutralizing agent and a first flocculant to the first filtrate, and control the pH of the system to reduce the concentration of Mn in the first filtrate. 2+ Complete catalytic oxidation simultaneously causes manganese, silicon, aluminum, and scandium ions to aggregate and co-precipitate. After solid-liquid separation, a second filtrate and a second precipitate are obtained. (3) Add a third neutralizing agent and a first reducing agent to the second filtrate to adjust the pH of the solution to 6.7~7.1, so that the nickel and cobalt ions in the second filtrate precipitate. After solid-liquid separation, nickel and cobalt precipitate and third filtrate are obtained. (4) Add a fourth neutralizing agent and a second reducing agent to the third filtrate, adjust the pH of the solution to 7.9~9.6, so that the nickel and cobalt ions in the third filtrate precipitate, and obtain a fourth precipitate and a fourth filtrate after solid-liquid separation; return the fourth precipitate to step (3) and mix it with the solution before the precipitation reaction in step (3); (5) The second precipitate is mixed with the third reducing agent and reduced and leached under low acid conditions to leach manganese, aluminum, silicon, and scandium in the second precipitate. The second agglomerating agent and the fifth neutralizing agent are added to adjust the pH of the solution to 3.8~4.9 to precipitate silicon and aluminum ions. After solid-liquid separation, silicon and aluminum precipitate residue and manganese and scandium filtrate are obtained. (6) Extract the manganese scandium filtrate so that scandium in the manganese scandium filtrate enters the extraction system and manganese in the manganese scandium filtrate enters the raffinate; (7) Add a catalytic oxidant and a sixth neutralizing agent to the raffinate, control the pH of the system so that the manganese ions are completely catalytically oxidized to manganese oxide, and separate the solid and liquid to obtain manganese oxide precipitate residue and manganese-precipitated nickel-cobalt solution. The manganese-precipitated nickel-cobalt solution is returned to step (3) and mixed with the solution before the precipitation reaction in step (3).

2. The method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution according to claim 1, characterized in that, The catalytic oxidant includes at least one of the following: a mixture of SO2 and air, flue gas containing sulfur dioxide, and a mixture of a solid additive capable of releasing SO2 and air. The solid additive includes one or more of metabisulfite, sulfite, bisulfite, and thiosulfate. The volume of SO2 in the catalytic oxidant accounts for 0.42% to 4.2% of the total gas volume in the catalytic oxidant. And / or, the reaction times of steps (1), (2), and (7) are the same or different, and are independently selected from 5 min to 600 min; And / or, the reaction temperatures of steps (1), (2), and (7) are the same or different, and are independently selected from 5 to 99 °C.

3. The method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution according to claim 1, characterized in that, In step (1), the addition of the catalytic oxidant makes the redox potential in step (1) 450mv-600mv; And / or, in step (2), the addition of the catalytic oxidant makes the redox potential in step (2) higher than 600 mV; And / or, in step (7), the addition of the catalytic oxidant makes the redox potential in step (7) higher than 600 mV.

4. The method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution according to claim 1, characterized in that, In step (1), the addition of the first neutralizing agent controls the pH of the system in step (1) to be 2.7-3.2; And / or, in step (2), the addition of the second neutralizing agent controls the pH of the system in step (2) to be 3.3-6.2; And / or, in step (7), the addition of the sixth neutralizing agent controls the pH of the system in step (7) to be 3.7-5.

6.

5. The method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution according to claim 1, characterized in that, The first neutralizing agent includes at least one of calcium oxide, calcium hydroxide, calcium carbonate, calcium bicarbonate, magnesium oxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water; The second, third, fourth, fifth, and sixth neutralizing agents independently include at least one of magnesium oxide, sodium hydroxide, calcium hydroxide, potassium hydroxide, magnesium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia.

6. The method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution according to claim 1, characterized in that, The first flocculant and the second flocculant independently include at least one of gelatin, guar gum, and plant gum.

7. The method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution according to claim 1, characterized in that, In step (2), the mass of the first coalescing agent accounts for 0.02-20% of the total mass of the reaction system in step (2); And / or, in step (5), the mass of the second coalescing agent accounts for 0.02-20% of the total mass of the reaction system in step (5).

8. The method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution according to claim 1, characterized in that, The first reducing agent, the second reducing agent, and the third reducing agent independently include any one of sulfur dioxide, sodium metabisulfite, sodium sulfite, thiosulfate, and hydrogen.

9. The method for catalytic oxidation-stepwise precipitation of laterite nickel ore leaching solution according to claim 1, characterized in that, The addition of the first reducing agent makes the redox potential in step (3) lower than 400mV; And / or, the addition of the second reducing agent makes the redox potential in step (4) lower than 400 mV; And / or, the addition of the third reducing agent makes the redox potential in step (5) lower than 350 mV.

10. The method for catalytic oxidation-stepwise precipitation of lateritic nickel ore leaching solution according to any one of claims 1-9, characterized in that, In step (5), the low acid condition refers to a pH of 0.2-3.2.

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