A method for recovering nickel and cobalt from laterite nickel ores

Abstract

The application discloses a method for recovering nickel and cobalt from laterite nickel ore, and the method comprises the following steps in sequence: grinding, pre-neutralization, synergistic pressure acid leaching, iron and aluminum removal, and nickel and cobalt precipitation. The method is targeted at the characteristics of laterite nickel ore and pyrite, and through the pre-neutralization and leaching steps, the acid and heat in the reaction process of the pyrite are fully utilized, thereby greatly reducing the steam heat source (saving 40% to 80%) and the amount of sulfuric acid (saving 80% to 99%) and improving the resource utilization rate of iron slag (the iron content is greater than 60%, which can be directly used as a raw material for ironmaking).

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgical technology, specifically relating to a method for recovering nickel and cobalt from laterite nickel ore. Background Technology

[0002] In low-grade lateritic nickel ore (Ni 0.8%–1.5%, Fe 40%–50%), nickel is isomorphously dissolved in the goethite (α-FeOOH) lattice, accompanied by extremely high iron content. This leads to two major challenges for traditional hydrometallurgical processes: 1. Existing high-pressure sulfuric acid leaching (HPAL) processes suffer from high acid and steam consumption (currently, each ton of low-grade lateritic nickel ore requires 250–500 kg of sulfuric acid and 1300–2500 t of steam). Furthermore, during the conversion of hematite, goethite (α-FeOOH) exhibits low reactivity in sulfuric acid, requiring excessive acid to disrupt its lattice and release nickel. This results in the formation of low-value iron slag (Fe content <60%) and high steam consumption during acid leaching. 2. The economic and environmental challenges of iron slag, particularly the high concentration of Fe in the leachate. 3+ Under high temperature and pressure, it hydrolyzes into amorphous FeOOH or hematite (Fe2O3). The resulting iron slag is difficult to utilize as a raw material for ironmaking due to its low grade and high impurities (high S content >2%).

[0003] To reduce acid consumption and improve the utilization rate of iron slag resources, existing technologies attempt to reduce goethite to magnetite (Fe3O4) using hydrogen or biomass to enhance the reaction efficiency of acid leaching. However, the investment in reduction equipment is high and the degree of reduction is difficult to control. In addition, ferrous sulfate is introduced, which to some extent increases the iron content in the leaching residue. However, the introduction of excessive sulfate will also increase the cost of subsequent neutralization. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide a method for recovering nickel and cobalt from laterite nickel ore with low acid consumption, low steam consumption, and high comprehensive utilization value of iron resources.

[0005] This invention provides a method for recovering nickel and cobalt from laterite nickel ore, comprising the following steps:

[0006] (1) Grinding: Lateritic nickel ore and pyrite are crushed and ground separately to obtain lateritic nickel ore powder and pyrite powder respectively;

[0007] (2) Pre-neutralization: After mixing the laterite nickel ore powder with the leaching solution in step (3), pre-neutralization is carried out. After pre-neutralization, neutralization residue and neutralization solution are obtained.

[0008] (3) Co-pressurized acid leaching: The neutralized residue from step (2), the pyrite powder from step (1), the nickel-cobalt precipitation solution from step (5), and concentrated sulfuric acid are mixed and slurryed to obtain a slurry; the slurry is added to the reactor, and steam and oxygen are introduced for co-pressurized acid leaching. After the leaching reaction is completed, the slurry is cooled and depressurized by three-stage flash evaporation, and then the liquid and solid are separated to obtain leaching residue and leaching solution; the leaching solution is returned to step (2) for pre-neutralization;

[0009] (4) Iron and aluminum removal: Add a neutralizing agent to the neutralized solution in step (2) and control the pH to 1.5~2 to carry out the neutralization reaction to remove iron and aluminum, and obtain iron and aluminum removal solution and iron and aluminum slag;

[0010] (5) Nickel-cobalt precipitation: Add a neutralizing agent to the iron-aluminum removal solution in step (4), control the pH to 8~8.5, and carry out a neutralization reaction. After the reaction is complete, separate the liquid and solid to obtain nickel-cobalt precipitation solution and nickel-cobalt slag. The nickel-cobalt precipitation solution is returned to step (3) for synergistic pressure acid leaching.

[0011] Preferably, before the method is run, after step (1), laterite nickel ore powder, pyrite powder, concentrated sulfuric acid and water are mixed to make a slurry; the slurry is added to the reactor, and steam and oxygen are introduced for synergistic pressurized acid leaching. After the leaching reaction is completed, the slurry is cooled and depressurized by three-stage flash evaporation, and then the liquid and solid are separated to obtain leaching residue and leaching liquid; the leaching liquid is returned to step (2) for pre-neutralization; after the neutralized liquid is processed by steps (4) and (5), nickel-cobalt precipitate solution is generated and returned to step (3).

[0012] More preferably, the amount of pyrite powder added is 8-18% of the mass of lateritic nickel ore powder, the amount of concentrated sulfuric acid added is 8-12% of the mass of lateritic nickel ore, and the liquid-solid ratio of the slurry is (1.5-2) mL:1g.

[0013] More preferably, the temperature of the synergistic pressure pickling is 245~260℃, the pressure of the synergistic pressure pickling is 4.0~5.0 MPa, and the time of the synergistic pressure pickling is 50~100 min.

[0014] Preferably, in step (1), the particle size of the laterite nickel ore powder and pyrite powder ground to a particle size of less than 100 mesh accounts for 90% or more.

[0015] Preferably, in step (2), the pre-neutralization temperature is 60~80℃, the pre-neutralization time is 1~3h, and the concentration of sulfuric acid in the neutralization solution is controlled to be 10~15g / L.

[0016] Preferably, in step (3), the amount of pyrite powder added is 10-20% of the mass of lateritic nickel ore, the amount of concentrated sulfuric acid added is 0.5%-5% of the mass of lateritic nickel ore, and the liquid-solid ratio of the slurry is (1.5-2) mL:1g.

[0017] Preferably, in step (3), the temperature of the synergistic pressurized acid leaching is 245~260℃, the pressure of the synergistic pressurized acid leaching is 4.0~5.0 MPa, the time of the synergistic pressurized acid leaching is 50~100 min, and the oxygen flow rate per kilogram of lateritic nickel ore during the synergistic pressurized acid leaching process is 2.0~2.5 Nm³. 3 The concentration of sulfuric acid in the leachate is 40~50g / L.

[0018] Preferably, in step (3), 5-10% of the leaching residue is returned to the slurry.

[0019] Preferably, in steps (4) and (5), the neutralizing agent is one or more of calcium carbonate and calcium oxide.

[0020] Preferably, in step (4), the neutralization reaction temperature is 80~90℃ and the neutralization reaction time is 1.5~3h.

[0021] Preferably, in step (4), 70-80% of the iron-aluminum slag is returned to the neutralization liquid.

[0022] Preferably, in step (5), the neutralization reaction temperature is 80~90℃ and the neutralization reaction time is 1.5~3h.

[0023] Preferably, in step (5), 60% to 70% of the nickel-cobalt slag is returned to the iron-aluminum removal liquid.

[0024] The concentrated sulfuric acid used in this invention has a mass concentration of 98%.

[0025] The gas volume unit Nm in this invention 3 It represents the volume in cubic meters at 1 standard atmosphere.

[0026] The above-described one or more technical solutions of the present invention can achieve at least one of the following beneficial effects:

[0027] (1) The method of recovering nickel and cobalt from laterite nickel ore of the present invention can make better use of the heat released by the endogenous sulfuric acid in pyrite and the generated sulfuric acid, thereby significantly reducing the amount of steam heat source and sulfuric acid used.

[0028] (2) The leaching residue obtained by the method of recovering nickel and cobalt from laterite nickel ore of the present invention is mainly composed of Fe2O3 mineral phase, with an iron content of more than 60wt% and a sulfur content of less than 1wt%, and can be directly used as raw material for ironmaking to realize the resource utilization of solid waste.

[0029] (3) In the method of the present invention, the leaching residue and iron-aluminum slag are returned as seed crystals, which inhibits the formation of amorphous iron phase, avoids scale adhesion in the reactor, reduces maintenance costs, and improves the solid-liquid separation effect.

[0030] (4) In the method of the present invention, based on the characteristics of laterite nickel ore and pyrite, through pre-neutralization, leaching and other steps, the acid and heat in the reaction process of pyrite are fully utilized, thereby greatly reducing the amount of steam heat source (saving 40%~80%) and sulfuric acid (saving 80%~99%) and improving the resource utilization rate of iron slag (iron content greater than 60%, which can be directly used as raw material for ironmaking). Attached Figure Description

[0031] Figure 1 This is a process flow diagram after the method of the present invention has been running stably. Detailed Implementation

[0032] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention. Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in this invention are commercially available or can be prepared by existing methods.

[0033] This invention provides a method for recovering nickel and cobalt from laterite nickel ore, comprising the following steps:

[0034] (1) Grinding: Lateritic nickel ore and pyrite are crushed and ground separately to obtain lateritic nickel ore powder and pyrite powder respectively;

[0035] (2) Pre-neutralization: After mixing the laterite nickel ore with the leaching solution in step (3), pre-neutralization is carried out. After pre-neutralization, neutralization residue and neutralization solution are obtained.

[0036] (3) Co-pressurized acid leaching: The neutralized residue from step (2), the pyrite powder from step (1), the nickel-cobalt precipitation solution from step (5), and sulfuric acid are mixed and slurryed to obtain a slurry; the slurry is pumped into the reactor, and steam and oxygen are introduced for co-pressurized acid leaching. After the leaching reaction is completed, the slurry is cooled and depressurized by three-stage flash evaporation, and then the liquid and solid are separated to obtain leaching residue and leaching solution; the leaching solution is returned to step (2) for pre-neutralization;

[0037] (4) Iron and aluminum removal: Add a neutralizing agent to the neutralized solution in step (2) and control the pH to 1.5~2 to carry out the neutralization reaction to remove iron and aluminum, and obtain iron and aluminum removal solution and iron and aluminum slag;

[0038] (5) Nickel-cobalt precipitation: Add a neutralizing agent to the iron-aluminum removal solution in step (4), control the pH to 8~8.5, and carry out a neutralization reaction. After the reaction is complete, separate the liquid and solid to obtain nickel-cobalt precipitation solution and nickel-cobalt slag. The nickel-cobalt precipitation solution is returned to step (3) for synergistic pressure acid leaching.

[0039] The method in this invention, through pre-neutralization and synergistic pressurized acid leaching with pyrite, can precisely control the orientation of iron elements, obtaining leaching residue with hematite (Fe2O3) as the main mineral phase and an iron content greater than 60%. This leaching residue can be directly used as a raw material for iron smelting. The specific mechanism is as follows: In the pre-neutralization step, some alkaline substances in the laterite nickel ore powder are consumed, reducing the competition between these alkaline substances and the target acid (used for leaching nickel-cobalt-iron) in the subsequent pressurized acid leaching. In the synergistic pressurized acid leaching step, under the high-temperature, high-pressure, and highly oxidizing environment, the dissolved ferrous ions (Fe2O3)... 2+ It is rapidly oxidized into ferric ions (Fe3+). 3+ ); Fe 3+ Under high temperature and low acidity conditions, hydrolysis and precipitation reaction preferentially occur: 2Fe 3+ + 3H₂O → Fe₂O₃ (hematite) + 6H₂O + Therefore, this invention can obtain leaching residue mainly composed of hematite. Compared with other iron precipitation forms (such as goethite FeOOH, jaundice KFe3(SO4)2(OH)6, etc.), hematite has advantages such as high crystallinity, fewer impurities (S, Al, Si, etc.), high iron content (theoretically up to 70%), easy dehydration, and good filtration performance, which are beneficial to the subsequent recycling of leaching residue.

[0040] Furthermore, in this invention, the laterite nickel ore undergoes a pre-neutralization step, consuming some alkaline substances. Therefore, the amount of sulfuric acid added in the synergistic pressurized acid leaching reactor is low, and with a low initial sulfuric acid content, pyrite (FeS2) undergoes an oxidative decomposition reaction under high temperature and high pressure, producing sulfuric acid and heat. The specific reaction process is as follows:

[0041] 4FeS2 + 15O2 + 2H2O → 2Fe2(SO4)3 + 2H2SO4 + heat

[0042] Fe2(SO4)3 + 3H2O → Fe2O3 (hematite) + 3H2SO4

[0043] Overall reaction: 4FeS2 + 15O2 + 8H2O → 2Fe2O3 (hematite) + 8H2SO4 + heat

[0044] The sulfuric acid (H2SO4) generated in the reaction directly contributes to the leaching of valuable metals such as nickel, cobalt, and iron in laterite nickel ore, thereby reducing the consumption of sulfuric acid. This oxidation reaction is a strongly exothermic reaction, which can generate a large amount of heat, significantly increasing the temperature of the leaching system itself, thus reducing steam consumption; the generated ferric sulfate will further hydrolyze to produce hematite, mainly Fe2O3.

[0045] Regarding the process innovation of this invention, by returning the pre-neutralization slag to the leaching system, the utilization of sulfuric acid generated from pyrite is maximized, significantly reducing the consumption of purchased sulfuric acid. Simultaneously, the large amount of reaction heat released by pyrite oxidation is directly used to maintain the high leaching temperature, drastically reducing the external steam supply required to maintain the leaching temperature. This deep integration and full utilization of pyrite reaction products (acid and heat) in pre-neutralization and leaching processes ultimately achieves a significant reduction in steam heat sources (saving 40%~80%), sulfuric acid consumption (saving 80%~99%), and improved resource utilization of iron slag (iron content greater than 60%, S < 1%, can be directly used as ironmaking raw material).

[0046] By controlling the recovery method of the present invention, the endogenous heat and endogenous sulfuric acid of pyrite can be fully utilized, thereby reducing the consumption of steam and sulfuric acid while ensuring the leaching effect of nickel.

[0047] The method in this invention allows for the further recovery of nickel and cobalt from the precipitated nickel-cobalt solution, thereby increasing the recovery rate of nickel and cobalt. Furthermore, it can reduce the use of fresh water and save water.

[0048] Before the method is run, after step (1), laterite nickel ore powder, pyrite powder, concentrated sulfuric acid and water are mixed to make a slurry. The slurry is added to the reactor and steam and oxygen are introduced for synergistic pressurized acid leaching. After the leaching reaction is completed, the slurry is cooled and depressurized by three-stage flash evaporation and then separated into liquid and solid to obtain leaching residue and leaching solution. The leaching solution is returned to step (2) for pre-neutralization. After the neutralized solution is processed through steps (4) and (5), nickel-cobalt precipitate solution is generated and returned to step (3).

[0049] More preferably, the amount of pyrite powder added is 8-18% of the mass of lateritic nickel ore powder, the amount of sulfuric acid added is 8-12% of the mass of lateritic nickel ore, and the liquid-solid ratio of the slurry is (1.5-2) mL:1g.

[0050] Further preferably, the synergistic pressure pickling temperature is 245~260℃, the synergistic pressure pickling pressure is 4.0~5.0 MPa, and the synergistic pressure pickling time is 50~100 min.

[0051] Preferably, in step (1), the particle size of the laterite nickel ore powder and pyrite powder ground to a particle size of less than 100 mesh accounts for 90% or more.

[0052] Preferably, in step (2), the pre-neutralization temperature is 60~80℃, the pre-neutralization time is 1~3h, and the concentration of sulfuric acid in the neutralization solution is controlled to be 10~15g / L.

[0053] Preferably, in step (3), the amount of pyrite powder added is 10-20% of the mass of lateritic nickel ore, the amount of concentrated sulfuric acid added is 0.5%-5% of the mass of lateritic nickel ore, and the liquid-solid ratio of the slurry is (1.5-2) mL:1g.

[0054] By controlling the amount of pyrite powder added, the consumption of sulfuric acid and steam can be reduced while ensuring the leaching effect of nickel. At the same time, it can ensure that the iron slag generated in the reactor during the synergistic pressurized acid leaching process has an iron content of more than 60%, which is conducive to the high-value recovery of iron resources.

[0055] Preferably, in step (3), the temperature of the co-pressurized acid leaching is 245~260℃, the pressure of the co-pressurized acid leaching is 4.0~5.0 MPa, the time of the co-pressurized acid leaching is 50~100 min, and the concentration of sulfuric acid in the leaching solution is 40~50 g / L; in the co-pressurized acid leaching, the oxygen flow rate per kilogram of lateritic nickel ore is 2.0~2.5 Nm³. 3 .

[0056] Preferably, in step (3), 5-10% of the leaching residue is returned to the slurry.

[0057] In this invention, the leaching residue is partially returned and can be used as seed crystals, which inhibits the formation of amorphous iron phase, effectively preventing iron slag from adhering and scaling in the reactor, reducing maintenance costs, and improving solid-liquid separation efficiency.

[0058] Preferably, in steps (4) and (5), the neutralizing agent is one or more of calcium carbonate and calcium oxide.

[0059] Preferably, in step (4), the neutralization reaction temperature is 80~90℃ and the neutralization reaction time is 1.5~3h.

[0060] Preferably, in step (4), 70-80% of the iron-aluminum slag is returned to the neutralization liquid.

[0061] In this invention, the iron and aluminum slag is partially recycled and can be used as seed crystals, which inhibits the formation of amorphous iron and aluminum hydroxides, promotes their nucleation and growth, and enhances the solid-liquid separation effect.

[0062] Preferably, in step (5), the neutralization reaction temperature is 80~90℃ and the neutralization reaction time is 1.5~3h.

[0063] Preferably, in step (5), 60% to 70% of the nickel-cobalt slag is returned to the iron-aluminum removal liquid.

[0064] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0065] The process flow of a method for recovering nickel and cobalt from laterite nickel ore in this invention after stable operation is as follows: Figure 1 As shown, the specific steps can be found in the embodiments.

[0066] The mass percentage (wt%) of the relevant components in the laterite nickel ore and pyrite used in the embodiments of the present invention can be seen in Tables 1 and 2.

[0067] Table 1 Laterite Nickel Ore

[0068]

[0069] Table 2 Pyrite

[0070]

[0071] Example 1

[0072] (1) Laterite nickel ore and pyrite are crushed and ground separately until the mineral particle size is below 100 mesh, accounting for 90% or more, to obtain laterite nickel ore powder and pyrite powder.

[0073] (2) Pre-neutralization: After mixing the laterite nickel ore powder with the leaching solution produced in step (3), the pre-neutralization reaction is carried out at 70°C for 2 hours. After the reaction is completed, the solid and liquid are separated to obtain the neutralization residue and the neutralization solution (the concentration of H2SO4 in the neutralization solution is about 12 g / L).

[0074] (3) The neutralization residue, pyrite powder, nickel-cobalt precipitation solution from step (5), and concentrated sulfuric acid are mixed and prepared into a slurry at a liquid-to-solid ratio of 1.74 mL: 1 g to obtain a slurry (wherein: the amount of pyrite added is 20% of the mass of lateritic nickel ore, and the amount of concentrated sulfuric acid added is 3% of the mass of lateritic nickel ore); the slurry is pumped into a reactor, and steam and oxygen are introduced for synergistic pressurized acid leaching, wherein: the oxygen consumption per kilogram of lateritic nickel ore is 2 Nm³. 3 The acid leaching temperature was 255℃, the acid leaching pressure was 4.5 MPa, and the acid leaching time was 60 min. After acid leaching, the slurry underwent three-stage flash evaporation to cool and depressurize, followed by liquid-solid separation. The resulting leaching residue (8 wt% of which was returned to the slurry as seed crystals) and leachate were returned to step (2) for pre-neutralization. The Fe content in the leaching residue was approximately 63.4 wt%, and the S content was 0.85 wt%. The H2SO4 concentration in the leachate was approximately 45 g / L. In this step, the leaching rates of nickel and cobalt were 95.5% and 95.4%, respectively.

[0075] (4) Add CaCO3 to the neutralized solution obtained in step (2), adjust the pH of the neutralized solution to 1.8, and carry out the reaction, wherein: the reaction temperature is 85℃ and the reaction time is 2h; after the reaction is completed, the solid and liquid are separated to obtain iron-aluminum removal solution (the concentration of Fe in the iron-aluminum removal solution is about 5mg / L and the concentration of Al is about 3mg / L) and iron-aluminum slag (the content of Ni in the iron-aluminum slag is about 0.006wt%, the content of Fe is about 1.2wt%, and the content of Al is about 9.95wt%), return 75wt% of the iron-aluminum slag to the neutralized solution as seed crystals, and the rest are stored.

[0076] (5) Add CaCO3 to the iron-aluminum removal solution in step (4), adjust the pH to 8.2, and carry out the reaction. The reaction temperature is controlled at 85℃ and the reaction time is 2h. After the reaction is completed, liquid-solid separation is performed to obtain nickel-cobalt precipitated solution and nickel-cobalt slag. The nickel-cobalt precipitated solution is returned to the acid leaching process in step (3). 65wt% of the nickel-cobalt slag is returned to the iron-aluminum removal solution as seed crystals, and the rest is sent for subsequent nickel-cobalt recovery. The Ni content in the nickel-cobalt slag is about 22.52wt%, the Ni recovery rate is 95.2%, the Co content is 4.42wt%, and the Co recovery rate is 94.66%. The Ni and Co contents in the nickel-cobalt precipitated solution are about 2mg / L and 3mg / L, respectively.

[0077] At the initial stage of the method operation, after step (1), lateritic nickel ore powder, pyrite powder, concentrated sulfuric acid, and water are mixed and prepared into a slurry at a liquid-to-solid ratio of 1.67 mL:1 g to obtain a slurry (wherein: the amount of pyrite added is 20% of the mass of lateritic nickel ore, and the amount of concentrated sulfuric acid added is 10% of the mass of lateritic nickel ore); the slurry is pumped into the reactor, and steam and oxygen are introduced for synergistic pressurized acid leaching, wherein: the oxygen consumption per kilogram of lateritic nickel ore is 2 Nm³. 3 The acid leaching temperature was 255℃, the acid leaching pressure was 4.5 MPa, and the acid leaching time was 60 min. After acid leaching, the slurry underwent three-stage flash evaporation to reduce temperature and pressure. After liquid-solid separation, the resulting leaching residue (8 wt% of the leaching residue was returned to the slurry as seed crystals) and leachate (the H2SO4 concentration in the leachate was approximately 45 g / L) were produced. The leachate was returned to step (2) for pre-neutralization. The resulting neutralized solution was processed through steps (4) and (5) to produce nickel-cobalt precipitated solution, which was then returned to step (3). Subsequent processes were carried out in a cycle according to steps (1) to (5).

[0078] After the system is running stably, in this embodiment, the final acid consumption per ton of laterite nickel ore is 30 kg, and the steam consumption is 360 t.

[0079] Comparative Example 1

[0080] (1) Laterite nickel ore and pyrite are crushed and ground separately until the mineral particle size is below 100 mesh, and 90% or more are ground to obtain laterite nickel ore powder and pyrite powder.

[0081] (2) Co-pressurized acid leaching: Lateritic nickel ore powder, pyrite powder, concentrated sulfuric acid, and water are mixed and prepared into a slurry at a liquid-to-solid ratio of 1.9 mL:1 g (wherein: the amount of pyrite added is 10% of the mass of lateritic nickel ore, and the amount of concentrated sulfuric acid added is 20% of the mass of lateritic nickel ore); the prepared slurry is pumped into the reactor, and steam and oxygen are introduced for co-pressurized acid leaching, wherein: the oxygen consumption per kilogram of lateritic nickel ore is 3.2 Nm³. 3 The acid leaching temperature was 255℃, the acid leaching pressure was 4.5 MPa, and the acid leaching time was 60 min. After acid leaching, the slurry underwent three-stage flash evaporation for cooling and depressurization, followed by liquid-solid separation. The resulting leaching residue (8 wt% of which was returned to the slurry as seed crystals) and leachate were obtained. The leaching residue contained approximately 50.3 wt% Fe and 6.8 wt% S; the leachate contained approximately 35 g / L of H₂SO₄. In this step, the leaching rates of nickel and cobalt were 94.6% and 93.8%, respectively.

[0082] (3) Add CaCO3 to the leachate in step (2), control the pH to 1.8, and carry out the reaction. The reaction temperature is 85℃ and the reaction time is 2h. After the reaction is complete, the solid and liquid are separated to obtain iron-aluminum removal solution (the concentration of Fe in the iron-aluminum removal solution is about 12.2mg / L and the concentration of Al is about 14.7mg / L) and iron-aluminum slag (the content of Ni in the iron-aluminum slag is about 0.010wt%, the content of Fe is about 0.86wt%, and the content of Al is about 7.05wt%). Return 75wt% of the iron-aluminum slag to the neutralization solution as seed crystals, and store the rest.

[0083] (4) Add CaCO3 to the iron and aluminum removal liquid in step (3), control the pH to 8.2, and carry out the reaction. The reaction temperature is 85℃ and the reaction time is 2h. After the reaction is completed, the liquid and solid are separated to obtain nickel-cobalt precipitate liquid and nickel-cobalt slag. 65wt% of the nickel-cobalt slag is returned to the iron and aluminum removal liquid as seed crystals, and the rest is sent to the subsequent recovery of nickel and cobalt. The Ni content in the nickel-cobalt slag is about 22.56wt%, the Ni recovery rate is about 93.6%, the Co content is about 4.21wt%, and the Co recovery rate is about 92.5%.

[0084] After the system is running stably, in this embodiment, the final acid consumption per ton of laterite nickel ore is 200 kg, and the steam consumption is 1565 t.

[0085] In Comparative Example 1, Ni and Co were recovered from laterite nickel ore using existing processes. It can be seen that the acid consumption and steam consumption are both high, and the iron content in the leaching residue is low while the sulfur content is high, which is not conducive to the subsequent recovery of the leaching residue.

[0086] Comparative Example 2

[0087] (1) Laterite nickel ore and pyrite are crushed and ground separately until the mineral particle size is below 100 mesh, accounting for 90% or more, to obtain laterite nickel ore powder and pyrite powder.

[0088] (2) The lateritic nickel ore powder, pyrite powder, the nickel-cobalt precipitation solution from step (4), and concentrated sulfuric acid are mixed and prepared into a slurry at a liquid-to-solid ratio of 1.74 mL: 1 g to obtain a slurry (wherein: the amount of pyrite added is 20% of the mass of the lateritic nickel ore, and the amount of concentrated sulfuric acid added is 3% of the mass of the lateritic nickel ore); the slurry is pumped into a reactor, and steam and oxygen are introduced for synergistic pressurized acid leaching, wherein: the oxygen consumption per kilogram of lateritic nickel ore is 3.8 Nm³. 3 The acid leaching temperature was 255℃, the acid leaching pressure was 4.5 MPa, and the acid leaching time was 60 min. After acid leaching, the slurry underwent three-stage flash evaporation for cooling and depressurization, followed by liquid-solid separation. The resulting leaching residue (8 wt% of which was returned to the slurry as seed crystals) and leachate were obtained. The leaching residue contained approximately 57.9 wt% Fe and 8.3 wt% S; the leachate contained approximately 47 g / L of H₂SO₄. In this step, the leaching rates of nickel and cobalt were 76.8% and 77.2%, respectively.

[0089] (3) Add CaCO3 to the leachate obtained in step (2), adjust the pH of the neutralization solution to 1.8, and carry out the reaction, wherein: the reaction temperature is 85℃ and the reaction time is 2h; after the reaction is completed, the solid and liquid are separated to obtain iron-aluminum removal solution (the concentration of Fe in the iron-aluminum removal solution is about 8.2mg / L and the concentration of Al is about 18.5mg / L) and iron-aluminum slag (the content of Ni in the iron-aluminum slag is about 0.065wt%, the content of Fe is about 1.87wt%, and the content of Al is about 8.95wt%), return 75wt% of the iron-aluminum slag to the neutralization solution as seed crystals, and the rest are stored.

[0090] (4) Add CaCO3 to the iron-aluminum removal solution in step (3), adjust the pH to 8.2, and carry out the reaction. The reaction temperature is controlled at 85℃ and the reaction time is 2h. After the reaction is completed, liquid-solid separation is carried out to obtain nickel-cobalt precipitated solution and nickel-cobalt slag. The nickel-cobalt precipitated solution is returned to the synergistic pressure acid leaching process in step (2). 65wt% of the nickel-cobalt slag is returned to the iron-aluminum removal solution for use as seed crystals, and the rest is sent for subsequent nickel-cobalt recovery. The Ni content in the nickel-cobalt slag is about 18.68wt%, and the Ni recovery rate is 75.8%. The Co content is about 3.63wt%, and the Co recovery rate is 76%.

[0091] At the beginning of the method operation, water is used in step (2) to replace the nickel-cobalt immersion solution in step (2), and the subsequent processes are carried out in a cycle according to steps (1) to (4).

[0092] After the system is running stably, in this embodiment, the final acid consumption per ton of laterite nickel ore is 30 kg, and the steam consumption is 1655 t.

[0093] In Comparative Example 2, although the acid consumption was reduced without pre-neutralization, the steam consumption remained high, and the synergistic effect of oxygen pressure acid leaching was poor, resulting in low recovery rates of Ni and Co. Furthermore, the leaching residue had a high sulfur content, which was not conducive to the subsequent recovery of the leaching residue.

[0094] Example 2

[0095] (1) Laterite nickel ore and pyrite are crushed and ground separately until the mineral particle size is below 100 mesh, accounting for 90% or more, to obtain laterite nickel ore powder and pyrite powder.

[0096] (2) Pre-neutralization: After mixing the laterite nickel ore powder with the leachate produced in step (3), the pre-neutralization reaction is carried out at 60°C for 3 hours. After the reaction is completed, the solid and liquid are separated to obtain the neutralization residue and the neutralization liquid (the concentration of H2SO4 in the neutralization liquid is about 15 g / L).

[0097] (3) The neutralization residue, pyrite powder, nickel-cobalt precipitation solution from step (5), and concentrated sulfuric acid are mixed and prepared into a slurry at a liquid-to-solid ratio of 1.57 mL: 1 g to obtain a slurry (wherein: the amount of pyrite added is 10% of the mass of lateritic nickel ore, and the amount of concentrated sulfuric acid added is 5% of the mass of lateritic nickel ore); the slurry is pumped into a reactor, and steam and oxygen are introduced for synergistic pressurized acid leaching, wherein: the oxygen consumption per kilogram of lateritic nickel ore is 2.2 Nm³. 3 The acid leaching temperature was 245℃, the acid leaching pressure was 5.0 MPa, and the acid leaching time was 100 min. After acid leaching, the slurry underwent three-stage flash evaporation to cool and depressurize, followed by liquid-solid separation. The resulting leaching residue (5 wt% of which was returned to the slurry as seed crystals) and leachate were returned to step (2) for pre-neutralization. The Fe content in the leaching residue was approximately 61.68 wt%, and the S content was 0.75 wt%. The H2SO4 concentration in the leachate was approximately 50 g / L. In this step, the leaching rates of nickel and cobalt were 96.7% and 96.5%, respectively.

[0098] (4) Add CaCO3 to the neutralized solution obtained in step (2), adjust the pH of the neutralized solution to 1.5, and carry out the reaction, wherein: the reaction temperature is 90℃ and the reaction time is 1.5h; after the reaction is completed, the solid and liquid are separated to obtain iron-aluminum removal solution (the concentration of Fe in the iron-aluminum removal solution is about 3.8mg / L and the concentration of Al is about 2.7mg / L) and iron-aluminum slag (the Ni content in the iron-aluminum slag is about 0.009wt%, the Fe content is about 1.18wt%, and the Al content is about 9.63wt%), return 80wt% of the iron-aluminum slag to the neutralized solution as seed crystals, and the rest are stored.

[0099] (5) Add CaCO3 to the iron-aluminum removal solution in step (4), adjust the pH to 8.5, and carry out the reaction. The reaction temperature is controlled at 90℃ and the reaction time is 1.5h. After the reaction is completed, liquid-solid separation is carried out to obtain nickel-cobalt precipitated solution and nickel-cobalt slag. The nickel-cobalt precipitated solution is returned to the acid leaching process in step (3). 70wt% of the nickel-cobalt slag is returned to the iron-aluminum removal solution for use as seed crystals, and the rest is sent for subsequent nickel-cobalt recovery. The Ni content in the nickel-cobalt slag is about 20.81wt%, the Ni recovery rate is 96.4%, the Co content is 4.06wt%, and the Co recovery rate is 95.3%. The Ni and Co contents in the nickel-cobalt precipitated solution are about 1.8mg / L and 2.6mg / L, respectively.

[0100] At the initial stage of the method operation, after step (1), lateritic nickel ore powder, pyrite powder, concentrated sulfuric acid, and water are mixed and prepared into a slurry at a liquid-to-solid ratio of 1.82 mL:1 g to obtain a slurry (wherein: the amount of pyrite added is 10% of the mass of lateritic nickel ore, and the amount of concentrated sulfuric acid added is 12% of the mass of lateritic nickel ore); the slurry is pumped into the reactor, and steam and oxygen are introduced for synergistic pressurized acid leaching, wherein: the oxygen consumption per kilogram of lateritic nickel ore is 2.2 Nm³. 3 The acid leaching temperature was 245℃, the acid leaching pressure was 5.0 MPa, and the acid leaching time was 100 min. After acid leaching, the slurry underwent three-stage flash evaporation to reduce temperature and pressure. After liquid-solid separation, the resulting leaching residue (8 wt% of the leaching residue was returned to the slurry as seed crystals) and leaching solution (the leaching solution contained approximately 50 g / L of H2SO4) were produced. The leaching solution was returned to step (2) for pre-neutralization. The resulting neutralized solution was then processed through steps (4) and (5) to produce nickel-cobalt precipitated solution, which was returned to step (3). Subsequent processes were carried out in a cycle according to steps (1) to (5).

[0101] After the system is running stably, in this embodiment, the final acid consumption per ton of laterite nickel ore is 50 kg, and the steam consumption is 680 t.

[0102] Example 3

[0103] (1) Laterite nickel ore and pyrite are crushed and ground separately until the mineral particle size is below 100 mesh, accounting for 90% or more, to obtain laterite nickel ore powder and pyrite powder.

[0104] (2) Pre-neutralization: After mixing the laterite nickel ore powder with the leaching solution produced in step (3), the pre-neutralization reaction is carried out at 80°C for 1 hour. After the reaction is completed, the solid and liquid are separated to obtain the neutralization residue and the neutralization solution (the concentration of H2SO4 in the neutralization solution is about 10 g / L).

[0105] (3) The neutralization residue, pyrite powder, nickel-cobalt precipitation solution from step (5), and concentrated sulfuric acid are mixed and prepared into a slurry at a liquid-to-solid ratio of 2 mL:1 g to obtain a slurry (wherein: the amount of pyrite added is 15% of the mass of lateritic nickel ore, and the amount of concentrated sulfuric acid added is 4% of the mass of lateritic nickel ore); the slurry is pumped into the reactor, and steam and oxygen are introduced for synergistic pressurized acid leaching, wherein: the oxygen consumption per kilogram of lateritic nickel ore is 2.5 Nm³. 3 The acid leaching temperature was 260℃, the acid leaching pressure was 5.0 MPa, and the acid leaching time was 50 min. After acid leaching, the slurry underwent three-stage flash evaporation to cool and depressurize, followed by liquid-solid separation. The resulting leaching residue (10 wt% of which was returned to the slurry as seed crystals) and leachate were returned to step (2) for pre-neutralization. The Fe content in the leaching residue was approximately 62.62 wt%, and the S content was 0.75 wt%. The H2SO4 concentration in the leachate was approximately 40 g / L. In this step, the leaching rates of nickel and cobalt were 95.2% and 96.7%, respectively.

[0106] (4) Add CaCO3 to the neutralized solution obtained in step (2), adjust the pH of the neutralized solution to 2.0, and carry out the reaction, wherein: the reaction temperature is 80℃ and the reaction time is 3h; after the reaction is completed, the solid and liquid are separated to obtain iron-aluminum removal solution (the concentration of Fe in the iron-aluminum removal solution is about 4.2mg / L and the concentration of Al is about 3.5mg / L) and iron-aluminum slag (the content of Ni in the iron-aluminum slag is about 0.039wt%, the content of Fe is about 2.43wt%, and the content of Al is about 12.3wt%), return 70wt% of the iron-aluminum slag to the neutralized solution as seed crystals, and the rest are stored.

[0107] (5) Add CaCO3 to the iron-aluminum removal solution in step (4), adjust the pH to 8.0, and carry out the reaction. The reaction temperature is controlled at 80℃ and the reaction time is 3h. After the reaction is completed, liquid-solid separation is carried out to obtain nickel-cobalt precipitated solution and nickel-cobalt slag. The nickel-cobalt precipitated solution is returned to the acid leaching process in step (3). 60wt% of the nickel-cobalt slag is returned to the iron-aluminum removal solution for use as seed crystals, and the rest is sent for subsequent nickel-cobalt recovery. The Ni content in the nickel-cobalt slag is about 23.75wt%, the Ni recovery rate is 93.9%, the Co content is 4.73wt%, and the Co recovery rate is 95.2%. The Ni and Co contents in the nickel-cobalt precipitated solution are about 2.2mg / L and 3.1mg / L, respectively.

[0108] At the initial stage of the method operation, after step (1), lateritic nickel ore powder, pyrite powder, concentrated sulfuric acid, and water are mixed and prepared into a slurry at a liquid-to-solid ratio of 1.74 mL:1 g (wherein: the amount of pyrite added is 15% of the mass of lateritic nickel ore, and the amount of concentrated sulfuric acid added is 8% of the mass of lateritic nickel ore); the slurry is pumped into the reactor, and steam and oxygen are introduced for synergistic pressurized acid leaching, wherein: the oxygen consumption per kilogram of lateritic nickel ore is 2.5 Nm³. 3The acid leaching temperature was 260℃, the acid leaching pressure was 5.0 MPa, and the acid leaching time was 50 min. After acid leaching, the slurry underwent three-stage flash evaporation to reduce temperature and pressure. After liquid-solid separation, the resulting leaching residue (8 wt% of the leaching residue was returned to the slurry as seed crystals) and leaching solution (the leaching solution contained approximately 40 g / L of H2SO4) were produced. The leaching solution was returned to step (2) for pre-neutralization. The resulting neutralized solution was then processed through steps (4) and (5) to produce a nickel-cobalt precipitate solution, which was returned to step (3). Subsequent processes were carried out in a cycle according to steps (1) to (5).

[0109] After the system is running stably, in this embodiment, the final acid consumption per ton of laterite nickel ore is approximately 40 kg, and the steam consumption is approximately 566 t.

[0110] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or additions made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for recovering nickel and cobalt from laterite nickel ore, characterized in that, Includes the following steps: (1) Grinding: Lateritic nickel ore and pyrite are crushed and ground separately to obtain lateritic nickel ore powder and pyrite powder respectively; (2) Pre-neutralization: After mixing the laterite nickel ore powder with the leaching solution in step (3), pre-neutralization is carried out. After pre-neutralization, neutralization residue and neutralization solution are obtained. (3) Co-pressurized acid leaching: The neutralized residue from step (2), the pyrite powder from step (1), the nickel-cobalt precipitation solution from step (5), and concentrated sulfuric acid are mixed and slurryed to obtain a slurry; the slurry is added to the reactor, and steam and oxygen are introduced for co-pressurized acid leaching. After the leaching reaction is completed, the slurry is cooled and depressurized by three-stage flash evaporation, and then the liquid and solid are separated to obtain leaching residue and leaching solution; the leaching solution is returned to step (2) for pre-neutralization; (4) Iron and aluminum removal: Add a neutralizing agent to the neutralized solution in step (2) and control the pH to 1.5~2 to carry out the neutralization reaction to remove iron and aluminum, and obtain iron and aluminum removal solution and iron and aluminum slag; (5) Nickel-cobalt precipitation: Add a neutralizing agent to the iron-aluminum removal solution in step (4), control the pH to 8~8.5, and carry out a neutralization reaction. After the reaction is complete, separate the liquid and solid to obtain nickel-cobalt precipitation solution and nickel-cobalt slag. The nickel-cobalt precipitation solution is returned to step (3) for synergistic pressure acid leaching.

2. The method for recovering nickel and cobalt from laterite nickel ore according to claim 1, characterized in that, Before the method is run, after step (1), laterite nickel ore powder, pyrite powder, concentrated sulfuric acid and water are mixed to make a slurry; the slurry is added to the reactor, and steam and oxygen are introduced for synergistic pressurized acid leaching. After the leaching reaction is completed, the slurry is cooled and depressurized by three-stage flash evaporation, and then the liquid and solid are separated to obtain leaching residue and leaching solution; the leaching solution is returned to step (2) for pre-neutralization. After passing through steps (4) and (5), the neutralized liquid produces a nickel-cobalt precipitate solution, which returns to step (3).

3. The method for recovering nickel and cobalt from laterite nickel ore according to claim 2, characterized in that, The amount of pyrite powder added is 8-18% of the mass of lateritic nickel ore powder, and the amount of concentrated sulfuric acid added is 8-12% of the mass of lateritic nickel ore; the liquid-solid ratio of the slurry is (1.5-2) mL: 1 g; The temperature of the synergistic pressure pickling is 245~260℃, the pressure of the synergistic pressure pickling is 4.0~5.0 MPa, and the time of the synergistic pressure pickling is 50~100 min.

4. The method for recovering nickel and cobalt from laterite nickel ore according to claim 1, characterized in that, In step (1), the proportion of the laterite nickel ore powder and pyrite powder ground to a particle size of less than 100 mesh is 90% or more.

5. The method for recovering nickel and cobalt from laterite nickel ore according to claim 1, characterized in that, In step (2), the pre-neutralization temperature is 60~80℃, the pre-neutralization time is 1~3h, and the concentration of sulfuric acid in the neutralized solution is 10~15g / L.

6. The method for recovering nickel and cobalt from laterite nickel ore according to claim 1, characterized in that, In step (3), the amount of pyrite powder added is 10-20% of the mass of lateritic nickel ore, and the amount of concentrated sulfuric acid added is 0.5-5% of the mass of lateritic nickel ore; the liquid-solid ratio of the slurry is (1.5-2) mL:1g.

7. The method for recovering nickel and cobalt from laterite nickel ore according to claim 1 or 6, characterized in that, In step (3), the temperature of the synergistic pressurized acid leaching is 245~260℃, the pressure of the synergistic pressurized acid leaching is 4.0~5.0 MPa, the time of the synergistic pressurized acid leaching is 50~100 min, and the oxygen flow rate per kilogram of lateritic nickel ore is 2~2.5 Nm³. 3 The concentration of sulfuric acid in the leachate is 40~50g / L.

8. The method for recovering nickel and cobalt from laterite nickel ore according to claim 1, characterized in that, In steps (4) and (5), the neutralizing agent is one or more of calcium carbonate and calcium oxide.

9. The method for recovering nickel and cobalt from laterite nickel ore according to claim 1 or 8, characterized in that, In step (4), the neutralization reaction temperature is 80~90℃ and the neutralization reaction time is 1.5~3h.

10. The method for recovering nickel and cobalt from laterite nickel ore according to claim 1 or 8, characterized in that, In step (5), the neutralization reaction temperature is 80~90℃ and the neutralization reaction time is 1.5~3h.

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