A comprehensive utilization method for laterite nickel ore

Abstract

This disclosure relates to a comprehensive utilization method for laterite nickel ore, comprising the following steps: (1) beneficiating laterite nickel ore to obtain chromium concentrate, low-nickel low-magnesium ore and high-nickel high-magnesium ore; (2) pulping low-nickel low-magnesium ore to obtain slurry, leaching the slurry, neutralizing, continuously countercurrent washing, solid-liquid separation to obtain filtrate and filter residue, neutralizing and removing impurities from the filtrate to obtain iron-aluminum slag and a solution containing nickel and cobalt, precipitating nickel and cobalt to obtain nickel-cobalt hydroxide; (3) crushing, screening, drying, calcining, adding gypsum, smelting to obtain low-grade nickel matte, and then oxidizing and blowing to obtain high-grade nickel matte; (4) adding the filter residue and iron-aluminum slag obtained in step (2) into a sulfuric acid solution, filtering to obtain filtrate and filter residue, evaporating and concentrating the obtained filtrate to obtain a water treatment coagulant, separating gypsum from the obtained filter residue and reusing it in the smelting process of step (3).

Description

Technical Field

[0001] This disclosure belongs to the field of laterite nickel ore metallurgical technology, and specifically relates to a comprehensive utilization method for laterite nickel ore. Background Technology

[0002] In recent years, with the continuous promotion and popularization of new energy electric vehicles and consumer electronics products, the global demand for lithium-ion rechargeable batteries has experienced explosive growth, leading to a surge in demand for nickel and nickel-based compounds—key materials for lithium-ion rechargeable batteries. Currently, the market supply of nickel products is mainly based on laterite nickel ore, accounting for over 65%.

[0003] The smelting of laterite nickel ore mainly falls into two categories: pyrometallurgical and hydrometallurgical processes. Conventional pyrometallurgical processes primarily employ the rotary kiln pre-reduction-electric furnace (RKEF) process. The advantages of this process are high-quality nickel-iron products and a relatively simple process flow; the disadvantages are high energy consumption, its suitability only for processing high-grade laterite nickel ore, and its inability to recover cobalt. Hydrometallurgical processes mainly utilize high-pressure acid leaching. High-pressure acid leaching has significant advantages in processing low-grade laterite nickel ore with high cobalt and iron content, and it consumes less energy; the disadvantages are higher plant construction costs, and the need for regular maintenance of the autoclave equipment due to corrosion and scaling during production. Therefore, both existing pyrometallurgical and hydrometallurgical processes have significant shortcomings in the smelting of laterite nickel ore. Summary of the Invention

[0004] This disclosure aims to address at least one of the technical problems existing in the related art. To this end, this disclosure proposes a comprehensive utilization method for laterite nickel ore. Based on the process characteristics of pyrometallurgical and hydrometallurgical processes, this method rationally optimizes the process flow, treats the iron and aluminum slag generated in hydrometallurgical processes and uses it as raw material for pyrometallurgical processes and water treatment, turning the iron and aluminum slag, which was originally treated as hazardous waste, into a valuable resource, improving its economic utilization value and reducing environmental pollution.

[0005] The above-mentioned technical objective of this disclosure is achieved through the following technical solution:

[0006] A comprehensive utilization method for laterite nickel ore includes the following steps:

[0007] (1) The laterite nickel ore is beneficiated to obtain chromium concentrate, low-nickel low-magnesium ore and high-nickel high-magnesium ore, wherein the chromium concentrate contains ≥20wt% chromium, the low-nickel low-magnesium ore contains ≤1.5wt% nickel and ≤3wt% magnesium, and the high-nickel high-magnesium ore contains ≥1.5wt% nickel and >3wt% magnesium.

[0008] (2) Hydrometallurgical process: The low-nickel and low-magnesium ore obtained in step (1) is slurried to obtain a slurry. The slurry is leached, neutralized, continuously countercurrent washed, and solid-liquid separated to obtain a filtrate and a filter residue. The filtrate is neutralized and impurities are removed to obtain iron-aluminum slag and a solution containing nickel and cobalt. Nickel and cobalt are precipitated to obtain nickel-cobalt hydroxide.

[0009] (3) Pyrometallurgical process: The high-nickel and high-magnesium ore obtained in step (1) is crushed, screened, dried, calcined, gypsum is added, and smelted to obtain low-grade nickel matte, which is then oxidized and blown to obtain high-grade nickel matte.

[0010] (4) Add the filter residue and iron-aluminum slag obtained in step (2) into sulfuric acid solution, filter to obtain filtrate and filter residue, evaporate and concentrate the obtained filtrate to obtain water treatment coagulant, and separate gypsum from the obtained filter residue for reuse in the smelting process of step (3).

[0011] In one embodiment, in step (1), the mineral processing is carried out by one of the following: trough washing machine, spiral chute, or shaking table.

[0012] In one embodiment, in step (2), the solid content of the slurry is 30wt%-40wt%, and the mass ratio of particles with a particle size of 8μm to the total solids is >80%.

[0013] In one embodiment, the high-nickel high-magnesium ore has a moisture content of 30wt%-40wt%, and the particle size of the crushed high-nickel high-magnesium ore is less than 25mm.

[0014] In one embodiment, in step (2), the leaching includes oxygen pressure leaching or high pressure leaching.

[0015] In one embodiment, the oxygen pressure leaching temperature is 170-185°C, the leaching pressure is 1.8-2.0 MPa, and the leaching time is 0.5-2.0 h.

[0016] In one embodiment, the high-pressure leaching temperature is 250-260°C, the leaching pressure is 4.3-5.2 MPa, and the leaching time is 0.5-2.0 h.

[0017] In one embodiment, in step (2), the neutralization before continuous countercurrent washing refers to adding limestone slurry for neutralization, and the pH value after neutralization with limestone slurry is 1.5-2.0.

[0018] In one embodiment, in step (2), the continuous countercurrent washing refers to using a thickener for six or seven stages of countercurrent washing, wherein the overflow from the first stage thickener enters the iron and aluminum removal process, and the underflow from the final stage thickener enters the tailings neutralization process for treatment.

[0019] In one embodiment, in step (2), the neutralization and impurity removal refers to adding limestone slurry and a mixed gas containing SO2 to the filtrate for neutralization and impurity removal, controlling the pH of the reaction to be 3.5-4.5 and the reaction temperature to be 55-65℃.

[0020] In one embodiment, in step (2), the mixed gas is a mixture of compressed air and SO2 gas, wherein the volume percentage of SO2 in the mixed gas is 0.5%-1%, and the pressure of the mixed gas is 0.2-0.5 MPa.

[0021] In one embodiment, in step (2), magnesium oxide is added to a nickel-cobalt containing solution to precipitate nickel-cobalt, and the pH of the reaction is controlled to be 6.5-7.5.

[0022] In one embodiment, in step (3), the drying temperature is 350-400°C, and the high-nickel high-magnesium ore has a moisture content of 20wt%-22wt% after drying.

[0023] In one embodiment, in step (3), a reducing agent and limestone are added during calcination to obtain calcined sand. The reducing agent is at least one of semi-coke and anthracite.

[0024] In one embodiment, in step (3), the calcination is carried out in a rotary kiln, the calcination temperature is 750-850℃, the calcination time is 1-3h, and the temperature of the calcined sand when it leaves the kiln after calcination is 700-750℃.

[0025] In one embodiment, in step (3), the mass ratio of the high-nickel high-magnesium ore, reducing agent and limestone added during calcination is 100:(5-10):(1-10).

[0026] In one embodiment, in step (3), the smelting is carried out in a side-blown furnace, specifically by adding calcined sand into the side-blown furnace while simultaneously adding sulfur, reducing agent and gypsum by side-blowing.

[0027] In one embodiment, in step (3), the melting temperature is 1500-1600℃ and the melting time is 2-3h.

[0028] In one embodiment, in step (3), the mass ratio of calcined sand: sulfur: reducing agent: gypsum added during the smelting is 100:(2-10):(5-10):(5-10).

[0029] In one embodiment, in step (3), the nickel content in the obtained low-grade nickel matte is 12wt%-30wt%.

[0030] In one embodiment, in step (3), after the low-grade nickel matte is smelted and removed from the furnace, the temperature is 1400-1500°C.

[0031] In one embodiment, in step (3), high-grade nickel matte is produced by intermittent blowing in a converter via ladle or by continuous operation using a top-blown furnace.

[0032] In one embodiment, in step (3), the temperature of the oxidation blowing is 1300-1400℃ and the blowing time is 6-8h.

[0033] In one embodiment, in step (3), the nickel content in the obtained high-grade nickel matte is 60wt%-75wt%.

[0034] In one embodiment, in step (3), the blowing slag produced during the blowing process is returned to the smelting process for the preparation of low-grade nickel matte. The nickel content in the blowing slag is 0.6 wt%-1.5 wt%.

[0035] In one embodiment, in step (3), the high-temperature flue gas generated in the side-blown furnace in the smelting process is returned to the rotary kiln in the calcination process as a heat source, and the temperature of the high-temperature flue gas generated in the smelting process is 1100-1300℃.

[0036] In one embodiment, in step (3), the flue gas after the heat utilization of the calcination process is discharged after being treated with limestone desulfurization.

[0037] In one embodiment, in step (3), the gypsum slag left after the rotary kiln flue gas treatment in the calcination process is dried and added to the side-blown furnace in the smelting process to participate in the sulfidation and slag formation of low-grade nickel matte.

[0038] In one embodiment, in step (4), the concentration of the sulfuric acid solution is 10wt%-30wt%.

[0039] In one embodiment, a method for the comprehensive utilization of laterite nickel ore includes the following steps:

[0040] (1) The laterite nickel ore is beneficiated to obtain chromium concentrate, low-nickel low-magnesium ore and high-nickel high-magnesium ore, wherein the chromium concentrate contains ≥20wt% chromium, the low-nickel low-magnesium ore contains ≤1.5wt% nickel and ≤3wt% magnesium, and the high-nickel high-magnesium ore contains ≥1.5wt% nickel and >3wt% magnesium.

[0041] (2) Hydrometallurgical process: The low-nickel and low-magnesium ore obtained in step (1) is slurried to obtain slurry, and then oxygen pressure leaching or high pressure leaching is performed. Limestone slurry is added for neutralization, and then continuous countercurrent washing is performed. Solid-liquid separation is performed to obtain filtrate and filter residue. Limestone slurry and mixed gas containing SO2 are added to the filtrate to obtain iron-aluminum slag and nickel-cobalt-containing solution. Magnesium oxide is added to the nickel-cobalt-containing solution to obtain nickel-cobalt hydroxide.

[0042] (3) Pyrometallurgical process: The high-nickel and high-magnesium ore obtained in step (1) is crushed, screened, dried, and then a reducing agent and limestone are added. The calcined ore is then calcined to obtain calcined sand. Then, a reducing agent, sulfur and gypsum are added and smelted to obtain low-grade nickel matte. Finally, the low-grade nickel matte is oxidized and blown to obtain high-grade nickel matte.

[0043] (4) Add the filter residue and iron-aluminum slag obtained in step (2) into sulfuric acid solution, filter to obtain filtrate and filter residue, evaporate and concentrate the obtained filtrate to obtain water treatment coagulant, and separate gypsum from the obtained filter residue for reuse in the smelting process of step (3).

[0044] The beneficial effects of this disclosure are:

[0045] (1) This disclosure discloses a comprehensive utilization method for laterite nickel ore. The method involves beneficiation of the laterite nickel ore, employing different smelting methods for laterite nickel ore with varying nickel content, thereby reducing production costs and improving production stability. Chromium concentrate can be sold directly, low-nickel and low-magnesium ore is processed into slurry for hydrometallurgical processing, and high-nickel and high-magnesium ore is sent to pyrometallurgical processing. In hydrometallurgical processing, the slurry undergoes high-pressure acid leaching or oxygen pressure leaching, leaching neutralization, continuous countercurrent washing, neutralization and impurity removal, and nickel-cobalt precipitation to obtain nickel-cobalt hydroxide. In pyrometallurgical processing, the laterite nickel ore undergoes drying in a drying kiln, calcination in a rotary kiln, smelting in a side-blown furnace, and oxidation smelting in a converter or top-blown furnace to obtain high-grade nickel matte. Simultaneously, the process is optimized based on the characteristics of both hydrometallurgical and pyrometallurgical processes.

[0046] The filtrate after continuous countercurrent washing in hydrometallurgical processes has a pH of around 3 and an Fe ion concentration of 3-5 g / L. This disclosure employs a hydrolysis method to remove Fe. Compared to iron removal using sodium ferrous sulfate, hydrolysis produces less slag. When removing iron and aluminum from the filtrate, the pH is controlled at 3.5-4.5, and the temperature at 55-65℃. Limestone slurry is added to neutralize the H2 produced during the hydrolysis reaction. + The reaction is as follows:

[0047] 2FeSO4+O2+2H2O=2FeOOH+2H2SO4;

[0048] Al2(SO4)3+6H2O=2Al(OH)3+3H2SO4;

[0049] H2SO4+CaCO3=CaSO4+H2O+CO2;

[0050] The main components of iron-aluminum slag are FeOOH, Al(OH)3, and CaSO4. In the past, the iron-aluminum slag produced was treated as hazardous waste, which required a lot of manpower, material resources, and financial resources. In this invention, dilute sulfuric acid is added to the iron-aluminum slag. The iron and aluminum dissolve into sulfates, and the insoluble CaSO4 (gypsum) is separated into solid and liquid and dried before being added to the oxygen-enriched side-blown furnace smelting process. At high temperature, CaSO4 decomposes into calcium oxide and sulfur dioxide, which participate in the low-grade nickel matte sulfidation. At the same time, calcium oxide is used as a slag-forming agent. The iron and aluminum sulfate solution is evaporated and concentrated and used as a coagulant for water treatment. The small amount of nickel and cobalt carried in the iron-aluminum slag enters the water treatment process together with the iron and aluminum sulfate solution and enters the recycling process.

[0051] (2) This disclosure adopts hydrometallurgical and pyrometallurgical processes to produce high-grade nickel matte according to the different nickel contents in laterite nickel ore. The pyrometallurgical process uses oxygen-enriched side-blown process to produce high-grade nickel matte, which replaces the traditional RKEF smelting of nickel-iron. Compared with the oxygen-enriched side-blown process, it has lower energy consumption and lower requirements for the grade of laterite nickel ore. The high-grade nickel matte product has higher economic value in subsequent production. At the same time, the process is optimized according to the process characteristics of pyrometallurgical and hydrometallurgical processes. The iron and aluminum slag produced in hydrometallurgical process is separated. The calcium sulfate obtained is dried and added to the oxygen-enriched side-blown furnace to participate in the sulfidation and slag formation of low-grade nickel matte. The iron and aluminum are converted into sulfate solution as a coagulant for the smelter water treatment. The gypsum slag produced after flue gas desulfurization in hydrometallurgical process is also added to the oxygen-enriched side-blown furnace for utilization. This method realizes the comprehensive utilization of resources, improves the mining value of laterite nickel ore, and reduces product costs. Attached Figure Description

[0052] Figure 1 This is a flowchart illustrating Embodiment 1 of the present disclosure. Detailed Implementation

[0053] The present disclosure will be further described below with reference to specific embodiments.

[0054] Example 1:

[0055] A comprehensive utilization method for laterite nickel ore, such as Figure 1 As shown, it includes the following steps:

[0056] (1) Laterite nickel ore is beneficiated by a trough washing machine to obtain chromium concentrate, low-nickel low-magnesium ore and high-nickel high-magnesium ore. Among them, the chromium content of the chromium concentrate is ≥20wt% and can be sold directly. The mass proportion of the components of the low-nickel low-magnesium ore is shown in Table 1-1 below:

[0057] Table 1-1: Composition of Low-Nickel, Low-Magnesium Ores

[0058]

[0059] The mass percentages of components in high-nickel, high-magnesium ores are shown in Table 1-2 below:

[0060] Table 1-2: Composition of high-nickel, high-magnesium ores

[0061]

[0062] (2) Hydrometallurgical process: The low-nickel and low-magnesium ore obtained in step (1) is prepared into a slurry with a solid content of 35%. The particles with a particle size of 8 μm account for more than 80% of the total solid mass. The slurry is leached under high pressure at 250℃ and 4.5 MPa for 1 hour. After high pressure leaching, limestone slurry is added to neutralize the excess acid in the leaching process. After neutralization, the pH value is controlled at 1.5. After six-stage continuous countercurrent washing, the solid and liquid are separated to obtain filtrate and filter residue. Limestone slurry and a mixed gas composed of compressed air and SO2 are added to the filtrate. The volume ratio of SO2 in the mixed gas is 0.8%, the pressure of the mixed gas is 0.3 MPa, the pH of the reaction is controlled at 4, and the reaction temperature is 60℃ to obtain iron-aluminum slag and a nickel-cobalt-containing solution. Magnesium oxide is added to the nickel-cobalt-containing solution, and the pH of the reaction is controlled at 7 to obtain nickel-cobalt intermediate products. The mass ratio of the components of the nickel-cobalt intermediate products is shown in Table 1-3 below.

[0063] Table 1-3: Composition of Nickel-Cobalt Intermediate Products

[0064]

[0065] (3) Pyrometallurgical smelting: The high-nickel and high-magnesium ore obtained in step (1) has a moisture content of 35 wt%. The high-nickel and high-magnesium ore is crushed to a particle size of less than 20 mm, screened, and then dried in a drying kiln to remove free water and some crystal water. The moisture content of the dried ore is 20%. After drying, semi-coke and limestone are added. The high-nickel and high-magnesium ore: semi-coke: limestone are added to a rotary kiln for calcination at a mass ratio of 100:10:5. The calcination temperature is 800℃ and the calcination time is 2 hours. The pre-reduction produces roasted sand, which is then fed into an oxygen-enriched side-blown furnace. Gypsum separated from the iron-aluminum slag in the wet smelting process and gypsum slag produced by flue gas desulfurization are added, along with sulfur and semi-coke for smelting at a temperature of 1550℃. The process takes 3 hours to obtain low-grade nickel matte, in which the mass ratio of calcined sand: semi-coke: sulfur: gypsum is 100:10:6:8. The low-grade nickel matte is transferred to a converter through a ladle for oxidation blowing to obtain high-grade nickel matte. The oxidation blowing temperature is 1300℃ and the blowing time is 8 hours. The blowing slag is returned to the oxygen-enriched side-blown furnace. The nickel content in the blowing slag is 1.0wt%. The high-temperature flue gas generated in the side-blown furnace during the smelting process is returned to the rotary kiln in the calcination process as a heat source. The temperature of the high-temperature flue gas generated in the smelting process is around 1200℃. The flue gas after heat utilization in the calcination process is discharged after limestone desulfurization treatment. The mass percentage of the components of the obtained high-grade nickel matte is shown in Table 1-4 below.

[0066] Table 1-4: Composition of High-Nickel Matte Products

[0067]

[0068] (4) Add the filter residue and iron-aluminum slag obtained in step (2) to a sulfuric acid solution with a concentration of 20wt%, filter to obtain filtrate and filter residue, evaporate and concentrate the obtained filtrate to obtain water treatment coagulant, and separate gypsum from the obtained filter residue for reuse in the smelting process of step (3).

[0069] In Example 1, the hydrometallurgical recovery rate of nickel was 94%, while the pyrometallurgical recovery rate was 90%.

[0070] Example 2:

[0071] A comprehensive utilization method for laterite nickel ore includes the following steps:

[0072] (1) Laterite nickel ore is beneficiated by spiral sluice to obtain chromium concentrate, low-nickel low-magnesium ore and high-nickel high-magnesium ore. Among them, the chromium content of the chromium concentrate is ≥20wt% and can be sold directly. The mass proportion of the components of the low-nickel low-magnesium ore is shown in Table 2-1 below:

[0073] Table 2-1: Composition of Low-Nickel, Low-Magnesium Ores

[0074]

[0075] The mass percentage of components in high-nickel, high-magnesium ores is shown in Table 2-2 below:

[0076] Table 2-2: Composition of high-nickel, high-magnesium ores

[0077]

[0078] (2) Hydrometallurgical process: The low-nickel and low-magnesium ore obtained in step (1) is prepared into a slurry with a solid content of 35%. The particles with a particle size of 8 μm account for more than 80% of the total solid mass. The ore is leached under oxygen pressure at 180℃ and 1.8 MPa for 1 hour. After high-pressure leaching, limestone slurry is added to neutralize the excess acid in the leaching process. After neutralization, the pH value is controlled at 1.5. After six-stage continuous countercurrent washing, the solid and liquid are separated to obtain filtrate and filter residue. Limestone slurry and a mixed gas composed of compressed air and SO2 are added to the filtrate. The volume ratio of SO2 in the mixed gas is 0.8%, the pressure of the mixed gas is 0.3 MPa, the pH of the reaction is controlled at 4, and the reaction temperature is 60℃ to obtain iron-aluminum slag and a nickel-cobalt-containing solution. Magnesium oxide is added to the nickel-cobalt-containing solution, and the pH of the reaction is controlled at 7 to obtain nickel-cobalt intermediate products. The mass ratio of the components of the nickel-cobalt intermediate products is shown in Table 2-3 below.

[0079] Table 2-3: Composition of Nickel-Cobalt Intermediate Products

[0080]

[0081] (3) Pyrometallurgical smelting: The high-nickel and high-magnesium ore obtained in step (1) has a moisture content of 35 wt%. The high-nickel and high-magnesium ore is crushed to a particle size of less than 20 mm, screened, and then dried in a drying kiln to remove free water and some crystal water. The moisture content of the dried ore is 20%. After drying, semi-coke and limestone are added. The high-nickel and high-magnesium ore: semi-coke: limestone are added to a rotary kiln for calcination at a mass ratio of 100:10:5. The calcination temperature is 800℃ and the calcination time is 2 hours. The pre-reduction produces roasted sand, which is then fed into an oxygen-enriched side-blown furnace. Gypsum separated from the iron-aluminum slag in the wet smelting process and gypsum slag produced by flue gas desulfurization are added, along with sulfur and semi-coke for smelting at a temperature of 1550℃. The process takes 3 hours to obtain low-grade nickel matte, in which the mass ratio of calcined sand: semi-coke: sulfur: gypsum is 100:10:6:8. The low-grade nickel matte is transferred to a converter through a ladle for oxidation blowing to obtain high-grade nickel matte. The oxidation blowing temperature is 1400℃ and the blowing time is 6 hours. The blowing slag is returned to the oxygen-enriched side-blown furnace. The nickel content in the blowing slag is 1.0wt%. The high-temperature flue gas generated in the side-blown furnace during the smelting process is returned to the rotary kiln in the calcination process as a heat source. The temperature of the high-temperature flue gas generated in the smelting process is around 1200℃. The flue gas after heat utilization in the calcination process is desulfurized by limestone and then discharged. The mass percentage of the components of the obtained high-grade nickel matte is shown in Table 2-4 below.

[0082] Table 2-4: Composition of High-Nickel Matte Products

[0083]

[0084] (4) Add the filter residue and iron-aluminum slag obtained in step (2) to a sulfuric acid solution with a concentration of 20wt%, filter to obtain filtrate and filter residue, evaporate and concentrate the obtained filtrate to obtain water treatment coagulant, and separate gypsum from the obtained filter residue for reuse in the smelting process of step (3).

[0085] In Example 2, the hydrometallurgical recovery rate of nickel was 93.5%, while the pyrometallurgical recovery rate was 89%.

Claims

1. A comprehensive utilization method of laterite nickel ore, characterized in that: Includes the following steps: (1) The laterite nickel ore is beneficiated to obtain chromium concentrate, low-nickel low-magnesium ore and high-nickel high-magnesium ore, wherein the chromium concentrate contains ≥20wt% chromium, the low-nickel low-magnesium ore contains ≤1.5wt% nickel and ≤3wt% magnesium, and the high-nickel high-magnesium ore contains ≥1.5wt% nickel and >3wt% magnesium. (2) Hydrometallurgical process: The low-nickel and low-magnesium ore obtained in step (1) is slurried to obtain a slurry. The slurry is leached, neutralized, continuously countercurrent washed, and solid-liquid separated to obtain a filtrate and a filter residue. The filtrate is neutralized and impurities are removed to obtain iron-aluminum slag and a solution containing nickel and cobalt. Nickel and cobalt are precipitated to obtain nickel-cobalt hydroxide. (3) Pyrometallurgical process: The high-nickel and high-magnesium ore obtained in step (1) is crushed, screened, dried, calcined, gypsum is added, and smelted to obtain low-grade nickel matte, which is then oxidized and blown to obtain high-grade nickel matte. (4) Add the filter residue and iron-aluminum slag obtained in step (2) to sulfuric acid solution, filter to obtain filtrate and filter residue, evaporate and concentrate the obtained filtrate to obtain water treatment coagulant, separate gypsum from the obtained filter residue and reuse it in the smelting process of step (3); In step (2), the neutralization and impurity removal refers to adding limestone slurry and mixed gas containing SO2 to the filtrate for neutralization and impurity removal, controlling the pH of the reaction to be 3.5-4.5 and the reaction temperature to be 55-65℃; In step (2), the mixed gas is a mixture of compressed air and SO2 gas, the volume percentage of SO2 in the mixed gas is 0.5%-1%, and the pressure of the mixed gas is 0.2-0.5MPa; In step (3), the high temperature flue gas generated by the side-blown furnace in the smelting process is returned to the rotary kiln in the calcination process as a heat source, and the temperature of the high temperature flue gas generated in the smelting process is 1100-1300℃.

2. The method for comprehensive utilization of laterite nickel ore according to claim 1, characterized in that: In step (1), the mineral processing is carried out by one of the following methods: trough washing machine, spiral chute, or shaking table.

3. The comprehensive utilization method of laterite nickel ore according to claim 1, characterized in that: In step (2), the solid content of the slurry is 30wt%-40wt%, and the mass ratio of particles with a particle size of 8um to the total solids is >80%.

4. The comprehensive utilization method of laterite nickel ore according to claim 1, characterized in that: The high-nickel and high-magnesium ore has a moisture content of 30wt%-40wt% and a particle size of less than 25mm after crushing.

5. The comprehensive utilization method of laterite nickel ore according to claim 1, characterized in that: In step (2), the leaching includes oxygen pressure leaching or high pressure leaching.

6. The method for comprehensive utilization of laterite nickel ore according to claim 5, characterized in that: The oxygen pressure leaching temperature is 170-185℃, the leaching pressure is 1.8-2.0MPa, and the leaching time is 0.5-2.0h.

7. A method for comprehensive utilization of laterite nickel ore according to claim 5, characterized in that: The high-pressure leaching temperature is 250-260℃, the leaching pressure is 4.3-5.2MPa, and the leaching time is 0.5-2.0h.

8. The method for comprehensive utilization of laterite nickel ore according to claim 1, characterized in that: In step (2), the neutralization before continuous countercurrent washing refers to adding limestone slurry for neutralization, and the pH value after neutralization with limestone slurry is 1.5-2.

0.

9. A method for comprehensive utilization of laterite nickel ore according to claim 1, characterized in that: The continuous countercurrent washing refers to using a thickener for six or seven stages of countercurrent washing, in which the overflow from the first stage thickener goes into the iron and aluminum removal process, and the underflow from the final stage thickener goes into the tailings neutralization process for treatment.

10. A method for comprehensive utilization of laterite nickel ore according to claim 1, characterized in that: In step (2), magnesium oxide is added to the nickel-cobalt-containing solution to precipitate nickel-cobalt, and the pH of the reaction is controlled to be 6.5-7.

5.

11. A method for comprehensive utilization of laterite nickel ore according to claim 1, characterized in that: In step (3), the drying temperature is 350-400℃, and the moisture content of the high-nickel and high-magnesium ore after drying is 20wt%-22wt%.

12. The method for comprehensive utilization of laterite nickel ore according to claim 1, characterized in that: In step (3), a reducing agent and limestone are added during calcination to obtain calcined sand. The reducing agent is at least one of semi-coke and anthracite.

13. A method for comprehensive utilization of laterite nickel ore according to claim 1, characterized in that: In step (3), the calcination is carried out in a rotary kiln at a temperature of 750-850℃ for 1-3 hours.

14. The method for comprehensive utilization of laterite nickel ore according to claim 1, characterized in that: In step (3), the mass ratio of high-nickel and high-magnesium ore, reducing agent and limestone added during calcination is 100: (5-10): (1-10).

15. A method for comprehensive utilization of laterite nickel ore according to claim 12, characterized in that: In step (3), the smelting is carried out in a side-blown furnace, specifically by adding calcined sand into the side-blown furnace and simultaneously adding sulfur, reducing agent and gypsum through side blowing.

16. A method for comprehensive utilization of laterite nickel ore according to claim 1, characterized in that: In step (3), the melting temperature is 1500-1600℃ and the melting time is 2-3h.

17. A method for comprehensive utilization of laterite nickel ore according to claim 15, characterized in that: In step (3), the mass ratio of calcined sand, sulfur, reducing agent and gypsum added during smelting is 100: (2-10): (5-10): (5-10).

18. A method for comprehensive utilization of laterite nickel ore according to claim 1, characterized in that: In step (3), the nickel content in the obtained low-grade nickel matte is 12wt%-30wt%.

19. A method for comprehensive utilization of laterite nickel ore according to claim 1, characterized in that: In step (3), high-grade nickel matte is produced by intermittent blowing in a converter via ladle or by continuous operation using a top-blown furnace.

20. A method for comprehensive utilization of laterite nickel ore according to claim 1, characterized in that: In step (3), the temperature of the oxidation blowing is 1300-1400℃ and the blowing time is 6-8h.

21. A method for comprehensive utilization of laterite nickel ore according to claim 1, characterized in that: In step (3), the nickel content in the obtained high-grade nickel matte is 60wt%-75wt%.

22. The method for comprehensive utilization of laterite nickel ore according to claim 1, characterized in that: In step (3), the slag produced by blowing is returned to the smelting process to prepare low-grade nickel matte, and the nickel content in the slag is 0.6wt%-1.5wt%.

23. The method for comprehensive utilization of laterite nickel ore according to claim 1, characterized in that: In step (3), the flue gas after the heat utilization of the calcination process is discharged after being treated by limestone desulfurization.

24. The method for comprehensive utilization of laterite nickel ore according to claim 1, characterized in that: In step (3), the gypsum slag left after the rotary kiln flue gas treatment in the calcination process is dried and added to the side-blown furnace in the smelting process to participate in the sulfidation and slag formation of low-grade nickel matte.

25. A method for comprehensive utilization of laterite nickel ore according to claim 1, characterized in that: In step (4), the concentration of the sulfuric acid solution is 10wt%-30wt%.

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