Method for recovering nickel and cobalt from laterite-nickel ore

Abstract

The invention discloses a method for recovering nickel and cobalt from laterite-nickel ore. The method sequentially comprises the steps of ore grinding, pre-neutralization, synergistic pressure acid leaching, iron and aluminum removal and nickel and cobalt precipitation. According to the method, acid and heat in the pyrite reaction process are fully utilized through the steps of pre-neutralization, leaching and the like according to the characteristics of the laterite-nickel ore and the pyrite, so that a steam heat source is greatly reduced (40%-80% of the steam heat source is saved), the use amount of sulfuric acid is reduced (80%-99% of the sulfuric acid is saved), and the resource utilization rate of the iron slag is increased (the iron content is larger than 60%, and the iron slag can be directly used as an ironmaking raw material).

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and in particular relates to a method for recovering nickel and cobalt from laterite nickel ore. Background Art

[0002] In low-grade laterite nickel ore (Ni 0.8%-1.5%, Fe 40%-50%), nickel is solid-dissolved in the goethite (α-FeOOH) lattice in an isomorphous form, and is accompanied by an ultra-high iron content, resulting in two core challenges for the traditional wet process: First, the existing sulfuric acid high-pressure acid leaching (HPAL) process has the problem of high acid and steam consumption (in the existing industry, each ton of low-grade laterite nickel ore requires 250kg-500kg of sulfuric acid and 1300-2500 t of steam). In addition, during the conversion process of hematite, goethite (α-FeOOH) has low reactivity in sulfuric acid, and excessive acid is required to destroy its lattice to release nickel. As a result, this type of process not only generates low-value iron slag (Fe content <60%), but also consumes a large amount of steam during the acid leaching process. Second, the economic and environmental dilemma of iron slag. In the leachate, high concentration of Fe 3+ It is hydrolyzed into amorphous FeOOH or hematite (Fe2O3) under high temperature and high pressure. The generated iron slag is difficult to be recycled as a raw material for ironmaking due to its low grade and high impurities (S content is high > 2%).

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

[0004] In view of this, the object of the present 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] The present invention provides a method for recovering nickel and cobalt from laterite nickel ore, comprising the following steps: (1) Grinding: crushing and grinding laterite nickel ore and pyrite to obtain laterite nickel ore powder and pyrite powder respectively; (2) Pre-neutralization: mixing the laterite nickel ore powder with the leachate in step (3), and then pre-neutralizing the mixture to obtain neutralized slag and neutralized liquid; (3) Synergistic pressure acid leaching: the neutralized slag in step (2), the pyrite powder in step (1), the nickel-cobalt precipitation solution in step (5), and concentrated sulfuric acid are mixed and slurried to obtain a pulp; the pulp is added to a reactor, steam and oxygen are introduced to perform synergistic pressure acid leaching; after the leaching reaction is completed, the pulp is subjected to three-stage flash evaporation for cooling and pressure reduction, and liquid-solid separation is performed to obtain a leaching slag and a leachate; the leachate is returned to step (2) for pre-neutralization; (4) Iron and aluminum removal: adding a neutralizing agent to the neutralized solution of step (2), controlling the pH to be 1.5-2 to carry out a neutralization reaction to remove iron and aluminum, and obtaining an iron and aluminum removal solution and iron and aluminum slag; (5) nickel-cobalt precipitation: a neutralizing agent is added to the iron-aluminum removal solution in step (4), and the pH is controlled to be 8-8.5 to carry out a neutralization reaction. After the reaction is completed, the nickel-cobalt precipitation solution and nickel-cobalt slag are obtained by liquid-solid separation; the nickel-cobalt precipitation solution is returned to step (3) for coordinated pressurized acid leaching.

[0006] Preferably, before the method is run, after step (1), laterite nickel ore powder, pyrite powder, concentrated sulfuric acid and water are mixed to prepare pulp to obtain ore pulp; the ore pulp is added to a reactor, steam and oxygen are introduced to carry out coordinated pressurized acid leaching, and after the leaching reaction is completed, the ore pulp is subjected to three-stage flash evaporation to reduce temperature and pressure, and liquid-solid separation is performed to obtain leaching residue and leachate; the leachate is returned to step (2) for pre-neutralization; the neutralized liquid is subjected to steps (4) and (5) to produce nickel-cobalt precipitation liquid, which is returned to step (3).

[0007] Further preferably, the amount of pyrite powder added is 8-18% of the mass of the laterite nickel ore powder, and the amount of concentrated sulfuric acid added is 8-12% of the mass of the laterite nickel ore; the liquid-to-solid ratio of the slurry is (1.5-2) mL:1 g.

[0008] More preferably, the temperature of the coordinated pressure acid leaching is 245-260° C., the pressure of the coordinated pressure acid leaching is 4.0-5.0 MPa, and the time of the coordinated pressure acid leaching is 50-100 min.

[0009] Preferably, in step (1), the laterite nickel ore powder and the pyrite powder are ground to a particle size of 90% or more below 100 mesh.

[0010] Preferably, in step (2), the pre-neutralization temperature is 60-80° C., the pre-neutralization time is 1-3 h, and the concentration of sulfuric acid in the neutralization solution is controlled to be 10-15 g / L.

[0011] Preferably, in step (3), the amount of pyrite powder added is 10-20% of the mass of the laterite nickel ore, and the amount of concentrated sulfuric acid added is 0.5-5% of the mass of the laterite nickel ore; the liquid-to-solid ratio of the slurry is (1.5-2) mL:1 g.

[0012] Preferably, in step (3), the temperature of the synergistic pressure acid leaching is 245-260°C, the pressure of the synergistic pressure acid leaching is 4.0-5.0 MPa, the time of the synergistic pressure acid leaching is 50-100 min, and the oxygen intake per kilogram of laterite nickel ore during the synergistic pressure acid leaching is 2.0-2.5 Nm 3 , leaching until the concentration of sulfuric acid in the leachate is 40~50g / L.

[0013] Preferably, in step (3), 5-10% of the leached residue is returned to the slurry.

[0014] Preferably, in steps (4) and (5), the neutralizing agent is one or more of calcium carbonate and calcium oxide.

[0015] Preferably, in step (4), the neutralization reaction temperature is 80-90° C., and the neutralization reaction time is 1.5-3 h.

[0016] Preferably, in step (4), 70-80% of the iron-aluminum slag is returned to the neutralization solution.

[0017] Preferably, in step (5), the neutralization reaction temperature is 80-90° C., and the neutralization reaction time is 1.5-3 h.

[0018] Preferably, in step (5), 60% to 70% of the nickel-cobalt slag is returned to the iron-removing aluminum liquid.

[0019] The mass concentration of the concentrated sulfuric acid used in the present invention is 98%.

[0020] The unit of gas volume in the present invention is Nm 3 Indicates the cubic volume under 1 standard atmosphere pressure.

[0021] The above one or more technical solutions of the present invention can achieve at least one of the following beneficial effects: (1) The method of recovering nickel and cobalt from laterite nickel ore of the present invention can better utilize 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.

[0022] (2) The leaching residue obtained by the method for recovering nickel and cobalt from laterite nickel ore of the present invention is mainly present in the Fe2O3 mineral phase, with an iron content greater than 60wt% and a sulfur content less than 1wt%. It can be directly used as an ironmaking raw material to realize solid waste resource utilization.

[0023] (3) In the method of the present invention, the leached slag and the iron-aluminum slag are partially returned as crystal seeds, thereby suppressing the formation of amorphous iron phase, avoiding adhesion and scaling in the reactor, reducing maintenance costs, and improving the solid-liquid separation effect.

[0024] (4) The method of the present invention takes into account the characteristics of laterite nickel ore and pyrite, and through pre-neutralization, leaching and other steps, fully utilizes the acid and heat in the pyrite reaction process, thereby significantly reducing the use of steam heat source (saving 40% to 80%) and sulfuric acid (saving 80% to 99%) and improving the resource utilization rate of iron slag (the iron content is greater than 60%, and it can be directly used as an ironmaking raw material). BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a process flow chart of the method of the present invention after stable operation. DETAILED DESCRIPTION

[0026] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the scope of the present invention. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0027] The present invention provides a method for recovering nickel and cobalt from laterite nickel ore, comprising the following steps: (1) Grinding: crushing and grinding laterite nickel ore and pyrite to obtain laterite nickel ore powder and pyrite powder respectively; (2) Pre-neutralization: mixing the laterite nickel ore with the leachate from step (3), and then pre-neutralizing the mixture to obtain neutralized slag and neutralized liquid; (3) Synergistic pressure acid leaching: the neutralized slag in step (2), the pyrite powder in step (1), the nickel-cobalt precipitation solution in step (5), and sulfuric acid are mixed and slurried to obtain a pulp; the pulp is pumped into a reactor, steam and oxygen are introduced to perform synergistic pressure acid leaching; after the leaching reaction is completed, the pulp is subjected to three-stage flash evaporation for cooling and pressure reduction, and liquid-solid separation is performed to obtain leaching slag and leachate; the leachate is returned to step (2) for pre-neutralization; (4) Iron and aluminum removal: adding a neutralizing agent to the neutralized solution of step (2), controlling the pH to be 1.5-2 to carry out a neutralization reaction to remove iron and aluminum, and obtaining an iron and aluminum removal solution and iron and aluminum slag; (5) nickel-cobalt precipitation: a neutralizing agent is added to the iron-aluminum removal solution in step (4), and the pH is controlled to be 8-8.5 to carry out a neutralization reaction. After the reaction is completed, the nickel-cobalt precipitation solution and nickel-cobalt slag are obtained by liquid-solid separation; the nickel-cobalt precipitation solution is returned to step (3) for coordinated pressurized acid leaching.

[0028] In the method of the present invention, the direction of the iron element can be precisely controlled through the pre-neutralization and pyrite co-pressure acid leaching steps, and the leaching slag with hematite (Fe2O3) as the main mineral phase and an iron content greater than 60% can be obtained. The leaching slag can be directly used as an ironmaking raw material. The specific mechanism is: in the pre-neutralization step, part of the alkaline substances in the laterite nickel ore powder is consumed, reducing the competitive consumption of the alkaline substances with the target acid (used to leach nickel, cobalt and iron) in the subsequent pressurized acid leaching. In the co-pressure acid leaching step, under the strong oxidizing environment of high temperature and pressure, the dissolved divalent iron ions (Fe 2+ ) is rapidly oxidized to ferric ions (Fe 3+ );Fe 3+ Under high temperature and low acidity conditions, hydrolysis and precipitation reactions occur first: 2Fe 3+ + 3H2O → Fe2O3 (hematite) + 6H + Thus, the present invention can produce a leaching residue primarily composed of hematite. Compared to other iron precipitates (such as goethite (FeOOH) and jarosite (KFe3(SO4)2(OH)6), hematite has advantages such as high crystallinity, less impurity (S, Al, Si, etc.), high iron content (theoretically up to 70%), easy dehydration, and good filtration properties, thus facilitating the subsequent recovery of leaching residue.

[0029] In addition, in the present invention, the laterite nickel ore is pre-neutralized, which consumes some alkaline substances; therefore, the amount of sulfuric acid added in the co-pressurized acid leaching reactor is low, and when the initial sulfuric acid content is low, pyrite (FeS2) undergoes an oxidative decomposition reaction under high temperature and high pressure, which can produce sulfuric acid and heat. The specific reaction process is as follows: 4FeS2+15O2+2H2O→2Fe2(SO4)3+2H2SO4+heat Fe2(SO4)3+ 3H2O → Fe2O3(hematite)+3H2SO4 Overall reaction: 4FeS2+15O2+8H2O→2Fe2O3(hematite)+8H2SO4+heat The sulfuric acid (H2SO4) generated by the reaction directly contributes to the leaching of valuable metals such as nickel, cobalt, and iron from the laterite nickel ore, thereby reducing sulfuric acid consumption. This oxidation reaction is highly exothermic, generating a large amount of heat, which significantly increases the temperature of the leaching system itself, thereby reducing steam consumption. The generated iron sulfate further hydrolyzes to form hematite, which is mainly composed of Fe2O3.

[0030] The process innovation of this method maximizes the utilization of sulfuric acid produced by pyrite by returning the pre-neutralization slag to the leaching system, significantly reducing the consumption of purchased sulfuric acid. Furthermore, the substantial heat released by pyrite oxidation is directly used to maintain high leaching temperatures, significantly reducing the external steam supply required to maintain leaching temperatures. This deep integration and full utilization of pyrite reaction products (acid and heat) across pre-neutralization and leaching ultimately achieves significant reductions in steam heat sources (saving 40%-80%), sulfuric acid usage (saving 80%-99%), and improved resource utilization of iron slag (with an iron content greater than 60% and sulfuric acid less than 1%), enabling direct use as an ironmaking raw material.

[0031] 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 nickel leaching effect.

[0032] In the method of the present invention, the nickel-cobalt precipitation solution is returned to further recover nickel and cobalt, thereby improving the recovery rate of nickel and cobalt; and the use of new water can also be reduced, thereby saving water.

[0033] Before the method is run, after step (1), laterite nickel ore powder, pyrite powder, concentrated sulfuric acid and water are mixed to prepare pulp to obtain ore pulp; the ore pulp is added to a reactor, steam and oxygen are introduced to carry out coordinated pressurized acid leaching, and after the leaching reaction is completed, the ore pulp is subjected to three-stage flash evaporation to reduce temperature and pressure, and liquid-solid separation is carried out to obtain leaching residue and leachate; the leachate is returned to step (2) for pre-neutralization; the neutralized liquid is subjected to steps (4) and (5) to produce nickel-cobalt precipitation liquid, which is returned to step (3).

[0034] Further preferably, the amount of pyrite powder added is 8-18% of the mass of the laterite nickel ore powder, the amount of sulfuric acid added is 8-12% of the mass of the laterite nickel ore; and the liquid-to-solid ratio of the slurry is (1.5-2) mL:1 g.

[0035] More preferably, the collaborative pressure pickling temperature is 245-260° C., the collaborative pressure pickling pressure is 4.0-5.0 MPa, and the collaborative pressure pickling time is 50-100 min.

[0036] Preferably, in step (1), the laterite nickel ore powder and the pyrite powder are ground to a particle size of 90% or more below 100 mesh.

[0037] Preferably, in step (2), the pre-neutralization temperature is 60-80° C., the pre-neutralization time is 1-3 h, and the concentration of sulfuric acid in the neutralization solution is controlled to be 10-15 g / L.

[0038] Preferably, in step (3), the amount of pyrite powder added is 10-20% of the mass of the laterite nickel ore, and the amount of concentrated sulfuric acid added is 0.5-5% of the mass of the laterite nickel ore; the liquid-to-solid ratio of the slurry is (1.5-2) mL:1 g.

[0039] By controlling the amount of pyrite powder added, the consumption of sulfuric acid and steam can be reduced while ensuring the nickel leaching effect. At the same time, it can ensure that the iron slag generated in the reactor during the coordinated pressurized acid leaching process has an iron content greater than 60%, which is conducive to the high-value recovery of iron resources.

[0040] Preferably, in step (3), the temperature of the synergistic pressure acid leaching is 245-260°C, the pressure of the synergistic pressure acid leaching is 4.0-5.0 MPa, the time of the synergistic pressure acid leaching is 50-100 min, and the concentration of sulfuric acid in the leachate is 40-50 g / L; in the synergistic pressure acid leaching, the oxygen introduction rate per kilogram of laterite nickel ore is 2.0-2.5 Nm 3 .

[0041] Preferably, in step (3), 5-10% of the leached residue is returned to the slurry.

[0042] In the present invention, the leached slag is partially returned and can be used as a crystal seed, thereby suppressing the formation of an amorphous iron phase, effectively preventing the iron slag from adhering to and scaling the reactor, reducing maintenance costs, and improving the solid-liquid separation effect.

[0043] Preferably, in steps (4) and (5), the neutralizing agent is one or more of calcium carbonate and calcium oxide.

[0044] Preferably, in step (4), the neutralization reaction temperature is 80-90° C., and the neutralization reaction time is 1.5-3 h.

[0045] Preferably, in step (4), 70-80% of the iron-aluminum slag is returned to the neutralization solution.

[0046] In the present invention, part of the iron-aluminum slag is returned and can be used as crystal seeds, thereby suppressing the generation of amorphous iron and aluminum hydroxides, facilitating their nucleation and growth, and enhancing the solid-liquid separation effect.

[0047] Preferably, in step (5), the neutralization reaction temperature is 80-90° C., and the neutralization reaction time is 1.5-3 h.

[0048] Preferably, in step (5), 60% to 70% of the nickel-cobalt slag is returned to the iron-removing aluminum liquid.

[0049] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0050] The process flow of the method for recovering nickel and cobalt from laterite nickel ore after stable operation of the present invention is as follows: Figure 1 The specific steps can be found in the embodiments.

[0051] The mass percentages (wt%) of the relevant components in the laterite nickel ore and pyrite used in the embodiments of the present invention can be found in Tables 1 and 2.

[0052] Table 1 Laterite nickel ore Table 2 Pyrite Example 1 (1) The laterite nickel ore and pyrite are crushed and ground separately until the mineral particle size is below 100 mesh and accounts for 90% or more, thereby obtaining laterite nickel ore powder and pyrite powder.

[0053] (2) Pre-neutralization: The laterite nickel ore powder is mixed with the leachate produced in step (3), and a 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 a neutralized slag and a neutralized liquid (the concentration of H2SO4 in the neutralized liquid is about 12 g / L).

[0054] (3) The neutralized slag, pyrite powder, the nickel-cobalt precipitation solution in step (5) and concentrated sulfuric acid are mixed at a liquid-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 laterite nickel ore, and the amount of concentrated sulfuric acid added is 3% of the mass of the laterite nickel ore); the slurry is pumped into a reactor, and steam and oxygen are introduced for coordinated pressurized acid leaching, wherein: the oxygen consumption per kilogram of laterite nickel ore is 2 Nm 3 The acid leaching temperature was 255°C, the acid leaching pressure was 4.5 MPa, and the acid leaching time was 60 min. After the acid leaching was completed, the slurry was cooled and depressurized by three-stage flash evaporation, and liquid-solid separation was performed. The leaching residue (8 wt% of the leaching residue was returned to the slurry as a seed crystal) and the leachate were produced. The leachate was 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 nickel and cobalt leaching rates were 95.5% and 95.4%, respectively.

[0055] (4) CaCO3 was added to the neutralized solution obtained in step (2), and the pH of the neutralized solution was adjusted to 1.8, and the reaction was carried out, wherein: the reaction temperature was 85°C and the reaction time was 2 h; after the reaction was completed, the solid-liquid separation was carried out to obtain iron-removing aluminum liquid (the concentration of Fe in the iron-removing aluminum liquid was about 5 mg / L, and the concentration of Al was about 3 mg / L) and iron-aluminum slag (the content of Ni in the iron-aluminum slag was about 0.006 wt%, the content of Fe was about 1.2 wt%, and the content of Al was about 9.95 wt%), and 75 wt% of the iron-aluminum slag was returned to the neutralized solution as a seed crystal, and the rest was stored.

[0056] (5) CaCO3 is added to the de-ironification and aluminum removal solution in step (4), and the pH is adjusted to 8.2, and a reaction is carried out, wherein: the reaction temperature is controlled to 85°C and the reaction time is 2 hours; after the reaction is completed, liquid-solid separation is carried out to obtain nickel-cobalt precipitation solution and nickel-cobalt slag; wherein: the nickel-cobalt precipitation solution is returned to the acid leaching process in step (3); 65wt% nickel-cobalt slag is returned to the de-ironification and aluminum removal solution for use as a crystal seed, and the rest is sent for subsequent nickel and cobalt recovery. The Ni content in the nickel-cobalt slag is approximately 22.52wt%, and 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 precipitation solution are approximately 2mg / L and 3mg / L, respectively.

[0057] At the beginning of the method operation, after step (1), laterite nickel ore powder, pyrite powder, concentrated sulfuric acid and water are mixed at a liquid-solid ratio of 1.67 mL:1 g to obtain a slurry (wherein: the amount of pyrite added is 20% of the mass of the laterite nickel ore, and the amount of concentrated sulfuric acid added is 10% of the mass of the laterite nickel ore); the slurry is pumped into a reactor, and steam and oxygen are introduced to perform coordinated pressurized acid leaching, wherein: the oxygen consumption per kilogram of laterite nickel ore is 2 Nm 3 The acid leaching temperature is 255°C, the acid leaching pressure is 4.5 MPa, and the acid leaching time is 60 min. After acid leaching, the pulp is subjected to three-stage flash evaporation to reduce temperature and pressure. After liquid-solid separation, the leaching residue (8wt% of the leaching residue is returned to the pulp as a seed crystal) and the leachate (the H2SO4 concentration in the leachate is about 45g / L) are produced. The leachate is returned to step (2) for pre-neutralization. The neutralized solution produced is subjected to steps (4) and (5) to produce a nickel-cobalt precipitation solution, which is returned to step (3). The subsequent process is carried out in a cycle according to steps (1) to (5).

[0058] After the system runs stably, the final acid consumption per ton of laterite nickel ore in this embodiment is 30 kg, and the steam consumption is 360 t.

[0059] Comparative Example 1 (1) The laterite nickel ore and pyrite are crushed and ground separately until the mineral particle size is below 100 mesh and the proportion thereof is 90% or more, thereby obtaining laterite nickel ore powder and pyrite powder.

[0060] (2) Synergistic pressure acid leaching: Laterite nickel ore powder, pyrite powder, concentrated sulfuric acid and water are mixed at a liquid-solid ratio of 1.9 mL:1 g to obtain a slurry (wherein: the amount of pyrite added is 10% of the mass of the laterite nickel ore, and the amount of concentrated sulfuric acid added is 20% of the mass of the laterite nickel ore); the adjusted slurry is pumped into the reactor, and steam and oxygen are introduced for synergistic pressure acid leaching, where: the oxygen consumption per kilogram of laterite nickel ore is 3.2 Nm 3 The acid leaching temperature is 255℃, the acid leaching pressure is 4.5Mpa, and the acid leaching time is 60min. After the acid leaching technology, the slurry is cooled and depressurized by three-stage flash evaporation, and the liquid-solid separation is carried out to produce leaching residue (8wt% leaching residue is returned to the slurry as a seed crystal) and leachate. The Fe content in the leaching residue is about 50.3wt%, and the S content is 6.8wt%; the H2SO4 concentration in the leachate is about 35g / L. In this step: the nickel and cobalt leaching rates are 94.6% and 93.8% respectively. (3) CaCO3 was added to the leachate in step (2), the pH was controlled to 1.8, and the reaction was carried out, wherein the reaction temperature was 85°C and the reaction time was 2 h; after the reaction was completed, the solid-liquid separation was carried out to obtain iron-removing aluminum liquid (the concentration of Fe in the iron-removing aluminum liquid was about 12.2 mg / L, and the concentration of Al was about 14.7 mg / L) and iron-aluminum slag (the content of Ni in the iron-aluminum slag was about 0.010 wt%, the content of Fe was about 0.86 wt%, and the content of Al was about 7.05 wt%), 75 wt% of the iron-aluminum slag was returned to the neutralization liquid as a seed crystal, and the rest was stored.

[0061] (4) CaCO3 was added to the de-ironing aluminum liquid in step (3), and the pH was controlled to 8.2 to carry out the reaction, wherein: the reaction temperature was 85°C and the reaction time was 2 h; after the reaction, the nickel-cobalt precipitate liquid and nickel-cobalt slag were obtained by liquid-solid separation; 65 wt% of the nickel-cobalt slag was returned to the de-ironing aluminum liquid for use as a crystal seed, and the rest was sent to the subsequent recovery of nickel and cobalt. The Ni content in the nickel-cobalt slag was about 22.56 wt%, and the Ni recovery rate was about 93.6%. The Co content was about 4.21 wt%, and the Co recovery rate was about 92.5%.

[0062] After the system runs stably, the final acid consumption per ton of laterite nickel ore in this embodiment is 200 kg, and the steam consumption is 1565 t.

[0063] In Comparative Example 1, Ni and Co were recovered from laterite nickel ore according to the existing process. It can be seen that the acid consumption and steam consumption were both high, and the iron content in the leaching residue was low and the sulfur content was high, which was not conducive to the subsequent recovery of the leaching residue.

[0064] Comparative Example 2 (1) The laterite nickel ore and pyrite are crushed and ground separately until the mineral particle size is below 100 mesh and accounts for 90% or more, thereby obtaining laterite nickel ore powder and pyrite powder.

[0065] (2) Mixing the laterite nickel ore powder, pyrite powder, the nickel-cobalt precipitation solution in step (4) and concentrated sulfuric acid at a liquid-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 laterite nickel ore, and the amount of concentrated sulfuric acid added is 3% of the mass of the laterite nickel ore); pumping the slurry into a reactor, introducing steam and oxygen for coordinated pressurized acid leaching, wherein: the oxygen consumption per kilogram of laterite nickel ore is 3.8 Nm 3 The acid leaching process was carried out at a temperature of 255°C, a pressure of 4.5 MPa, and a leaching time of 60 minutes. After leaching, the slurry was cooled and depressurized through three stages of flash evaporation for liquid-solid separation. This produced a leaching residue (8wt% of the leaching residue was returned to the slurry as seed crystals) and a leachate. The Fe content in the leaching residue was approximately 57.9wt%, and the S content was 8.3wt%. The H2SO4 concentration in the leachate was approximately 47g / L. In this step, the nickel and cobalt leaching rates were 76.8% and 77.2%, respectively.

[0066] (3) CaCO3 is added to the leachate obtained in step (2), the pH of the neutralization solution is adjusted to 1.8, and the reaction is carried out, wherein: the reaction temperature is 85°C and the reaction time is 2 h; after the reaction is completed, the solid and liquid are separated to obtain iron-removing aluminum liquid (the concentration of Fe in the iron-removing aluminum liquid is about 8.2 mg / L, and the concentration of Al is about 18.5 mg / L) and iron-aluminum slag (the content of Ni in the iron-aluminum slag is about 0.065 wt%, the content of Fe is about 1.87 wt%, and the content of Al is about 8.95 wt%), and 75 wt% of the iron-aluminum slag is returned to the neutralization solution as a seed crystal, and the rest is stored.

[0067] (4) CaCO3 is added to the de-ironification and aluminum removal solution in step (3), and the pH is adjusted to 8.2, and a reaction is carried out, wherein: the reaction temperature is controlled to 85°C and the reaction time is 2 hours; after the reaction is completed, liquid-solid separation is carried out to obtain a nickel-cobalt precipitation solution and a nickel-cobalt slag; wherein: the nickel-cobalt precipitation solution is returned to the coordinated pressurized acid leaching process in step (2); 65wt% of the nickel-cobalt slag is returned to the de-ironification and aluminum removal solution for use as a crystal seed, and the rest is sent to subsequent nickel and cobalt recovery. The nickel content in the nickel-cobalt slag is approximately 18.68wt%, and the Ni recovery rate is 75.8%; the Co content is approximately 3.63wt%, and the Co recovery rate is 76%.

[0068] At the beginning of the method operation, water is used in step (2) to replace the nickel-cobalt precipitation solution in step (2), and the subsequent process is carried out in a cycle according to steps (1) to (4).

[0069] After the system runs stably, the final acid consumption per ton of laterite nickel ore in this embodiment is 30 kg, and the steam consumption is 1655 t.

[0070] In Comparative Example 2, no pre-neutralization was performed. Although the acid consumption was reduced, the steam consumption was still high, and the synergistic oxygen pressure acid leaching effect was poor, resulting in a low recovery rate of Ni and Co. Moreover, the sulfur content in the leached residue was high, which was not conducive to the subsequent recovery of the leached residue.

[0071] Example 2 (1) The laterite nickel ore and pyrite are crushed and ground separately until the mineral particle size is below 100 mesh and accounts for 90% or more, thereby obtaining laterite nickel ore powder and pyrite powder.

[0072] (2) Pre-neutralization: The laterite nickel ore powder is mixed with the leachate produced in step (3), and a 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 a neutralized slag and a neutralized liquid (the concentration of H2SO4 in the neutralized liquid is about 15g / L).

[0073] (3) The neutralized slag, pyrite powder, the nickel-cobalt precipitation solution in step (5) and concentrated sulfuric acid are mixed 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 the laterite nickel ore, and the amount of concentrated sulfuric acid added is 5% of the mass of the laterite nickel ore); the slurry is pumped into a reactor, and steam and oxygen are introduced for coordinated pressurized acid leaching, wherein: the oxygen consumption per kilogram of laterite nickel ore is 2.2 Nm 3 The acid leaching temperature was 245°C, the acid leaching pressure was 5.0 MPa, and the acid leaching time was 100 min. After the acid leaching was completed, the slurry was cooled and depressurized by three-stage flash evaporation, and liquid-solid separation was performed. The leaching residue (5 wt% of the leaching residue was returned to the slurry as a seed crystal) and the leachate were produced. The leachate was 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 nickel and cobalt leaching rates were 96.7% and 96.5%, respectively.

[0074] (4) CaCO3 was added to the neutralized solution obtained in step (2), and the pH of the neutralized solution was adjusted to 1.5, and the reaction was carried out, wherein: the reaction temperature was 90°C and the reaction time was 1.5 h; after the reaction was completed, the solid-liquid separation was carried out to obtain iron-removing aluminum liquid (the concentration of Fe in the iron-removing aluminum liquid was about 3.8 mg / L, and the concentration of Al was about 2.7 mg / L) and iron-aluminum slag (the content of Ni in the iron-aluminum slag was about 0.009 wt%, the content of Fe was about 1.18 wt%, and the content of Al was about 9.63 wt%), and 80 wt% of the iron-aluminum slag was returned to the neutralized solution as a seed crystal, and the rest was stored.

[0075] (5) CaCO3 is added to the de-ironification and aluminum removal solution in step (4), and the pH is adjusted to 8.5, and a reaction is carried out, wherein: the reaction temperature is controlled to 90°C and the reaction time is 1.5 hours; after the reaction is completed, liquid-solid separation is carried out to obtain a nickel-cobalt precipitation solution and a nickel-cobalt slag; wherein: the nickel-cobalt precipitation solution is returned to the acid leaching process in step (3); 70wt% of the nickel-cobalt slag is returned to the de-ironification and aluminum removal solution for use as a crystal seed, and the rest is sent for subsequent nickel and cobalt recovery. The Ni content in the nickel-cobalt slag is approximately 20.81wt%, and 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 precipitation solution are approximately 1.8mg / L and 2.6mg / L, respectively.

[0076] At the beginning of the method operation, after step (1), laterite nickel ore powder, pyrite powder, concentrated sulfuric acid and water are mixed at a liquid-solid ratio of 1.82 mL:1 g to obtain a slurry (wherein: the amount of pyrite added is 10% of the mass of the laterite nickel ore, and the amount of concentrated sulfuric acid added is 12% of the mass of the laterite nickel ore); the slurry is pumped into a reactor, and steam and oxygen are introduced for coordinated pressurized acid leaching, wherein: the oxygen consumption per kilogram of laterite nickel ore is 2.2 Nm 3 The acid leaching temperature is 245°C, the acid leaching pressure is 5.0 MPa, and the acid leaching time is 100 min. After acid leaching, the pulp is subjected to three-stage flash evaporation to reduce temperature and pressure. After liquid-solid separation, the leaching residue (8wt% of the leaching residue is returned to the pulp as a seed crystal) and the leachate (the H2SO4 in the leachate is about 50g / L) are produced. The leachate is returned to step (2) for pre-neutralization. The neutralized solution produced is subjected to steps (4) and (5) to produce a nickel-cobalt precipitation solution, which is returned to step (3). The subsequent process is carried out in a cycle according to steps (1) to (5).

[0077] After the system runs stably, the final acid consumption per ton of laterite nickel ore in this embodiment is 50 kg, and the steam consumption is 680 t.

[0078] Example 3 (1) The laterite nickel ore and pyrite are crushed and ground separately until the mineral particle size is below 100 mesh and accounts for 90% or more, thereby obtaining laterite nickel ore powder and pyrite powder.

[0079] (2) Pre-neutralization: The laterite nickel ore powder is mixed with the leachate produced in step (3), and then pre-neutralized at 80°C for 1 hour. After the reaction is completed, the solid and liquid are separated to obtain neutralized slag and neutralized liquid (the concentration of H2SO4 in the neutralized liquid is about 10 g / L).

[0080] (3) The neutralized slag, pyrite powder, the nickel-cobalt precipitation solution in step (5) and concentrated sulfuric acid are mixed at a liquid-solid ratio of 2 mL:1 g to obtain a slurry (wherein: the amount of pyrite added is 15% of the mass of the laterite nickel ore, and the amount of concentrated sulfuric acid added is 4% of the mass of the laterite nickel ore); the slurry is pumped into a reactor, and steam and oxygen are introduced for coordinated pressurized acid leaching, wherein: the oxygen consumption per kilogram of laterite nickel ore is 2.5 Nm 3 The acid leaching temperature was 260°C, the acid leaching pressure was 5.0 MPa, and the acid leaching time was 50 min. After the acid leaching was completed, the slurry was cooled and depressurized by three-stage flash evaporation, and liquid-solid separation was performed. The leaching residue (10 wt% of the leaching residue was returned to the slurry as a seed crystal) and the leaching liquid were produced. The leaching liquid was 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 leaching liquid was approximately 40 g / L. In this step, the nickel and cobalt leaching rates were 95.2% and 96.7%, respectively.

[0081] (4) CaCO3 was added to the neutralized solution obtained in step (2), and the pH of the neutralized solution was adjusted to 2.0, and the reaction was carried out, wherein: the reaction temperature was 80°C and the reaction time was 3 h; after the reaction was completed, the solid-liquid separation was carried out to obtain iron-removing aluminum liquid (the concentration of Fe in the iron-removing aluminum liquid was about 4.2 mg / L, and the concentration of Al was about 3.5 mg / L) and iron-aluminum slag (the content of Ni in the iron-aluminum slag was about 0.039 wt%, the content of Fe was about 2.43 wt%, and the content of Al was about 12.3 wt%), and 70 wt% of the iron-aluminum slag was returned to the neutralized solution as a seed crystal, and the rest was stored.

[0082] (5) CaCO3 is added to the de-ironification and aluminum removal solution in step (4), the pH is adjusted to 8.0, and a reaction is carried out, wherein: the reaction temperature is controlled to 80°C and the reaction time is 3 hours; after the reaction is completed, liquid-solid separation is carried out to obtain a nickel-cobalt precipitation solution and a nickel-cobalt slag; wherein: the nickel-cobalt precipitation solution is returned to the acid leaching process in step (3); 60wt% of the nickel-cobalt slag is returned to the de-ironification and aluminum removal solution for use as a seed crystal, and the rest is sent for subsequent nickel and cobalt recovery. The Ni content in the nickel-cobalt slag is approximately 23.75wt%, and 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 precipitation solution are approximately 2.2mg / L and 3.1mg / L, respectively.

[0083] At the beginning of the method operation, after step (1), laterite nickel ore powder, pyrite powder, concentrated sulfuric acid and water are mixed at a liquid-solid ratio of 1.74 mL:1 g to obtain a slurry (wherein: the amount of pyrite added is 15% of the mass of the laterite nickel ore, and the amount of concentrated sulfuric acid added is 8% of the mass of the laterite nickel ore); the slurry is pumped into a reactor, and steam and oxygen are introduced for coordinated pressurized acid leaching, wherein: the oxygen consumption per kilogram of laterite nickel ore is 2.5 Nm 3The acid leaching temperature is 260°C, the acid leaching pressure is 5.0 MPa, and the acid leaching time is 50 min. After acid leaching, the pulp is subjected to three-stage flash evaporation to reduce temperature and pressure. After liquid-solid separation, the leaching residue (8wt% of the leaching residue is returned to the pulp as a seed crystal) and the leachate (the H2SO4 in the leachate is about 40g / L) are produced. The leachate is returned to step (2) for pre-neutralization. The neutralized solution produced is subjected to steps (4) and (5) to produce a nickel-cobalt precipitation solution, which is returned to step (3). The subsequent process is carried out in a cycle according to steps (1) to (5).

[0084] After the system runs stably, in this embodiment, the final acid consumption per ton of laterite nickel ore is about 40 kg, and the steam consumption is about 566 t.

[0085] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the present invention and implement it accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent variations or additions based on the spirit and substance of the present invention are intended to be encompassed 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: The following steps are involved: (1) Grinding: crushing and grinding laterite nickel ore and pyrite to obtain laterite nickel ore powder and pyrite powder respectively; (2) Pre-neutralization: mixing the laterite nickel ore powder with the leachate in step (3), and then pre-neutralizing the mixture to obtain neutralized slag and neutralized liquid; (3) Synergistic pressure acid leaching: the neutralized slag in step (2), the pyrite powder in step (1), the nickel-cobalt precipitation solution in step (5), and concentrated sulfuric acid are mixed and slurried to obtain a pulp; the pulp is added to a reactor, steam and oxygen are introduced to perform synergistic pressure acid leaching; after the leaching reaction is completed, the pulp is subjected to three-stage flash evaporation for cooling and pressure reduction, and liquid-solid separation is performed to obtain a leaching slag and a leachate; the leachate is returned to step (2) for pre-neutralization; (4) Iron and aluminum removal: adding a neutralizing agent to the neutralized solution of step (2), controlling the pH to 1.5-2 to carry out a neutralization reaction to remove iron and aluminum, and obtaining an iron and aluminum removal solution and iron and aluminum slag; (5) nickel-cobalt precipitation: a neutralizing agent is added to the iron-aluminum removal solution in step (4), and the pH is controlled to be 8-8.5 to carry out a neutralization reaction. After the reaction is completed, the nickel-cobalt precipitation solution and nickel-cobalt slag are obtained by liquid-solid separation; the nickel-cobalt precipitation solution is returned to step (3) for coordinated pressurized acid leaching.

2. The method for recovering nickel and cobalt from laterite nickel ore according to claim 1, wherein: Before the method is run, after step (1), laterite nickel ore powder, pyrite powder, concentrated sulfuric acid and water are mixed to prepare pulp to obtain ore pulp; the ore pulp is added to a reactor, steam and oxygen are introduced to carry out coordinated pressurized acid leaching, and after the leaching reaction is completed, the ore pulp is subjected to three-stage flash evaporation, cooling and pressure reduction, and liquid-solid separation to obtain leaching residue and leachate; the leachate is returned to step (2) for pre-neutralization; After the neutralization liquid passes through steps (4) and (5), a nickel-cobalt precipitation liquid is produced and returned to step (3).

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

4. The method for recovering nickel and cobalt from laterite nickel ore according to claim 1, wherein: In step (1), the laterite nickel ore powder and the pyrite powder are ground to a particle size of 90% or more below 100 mesh.

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

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

7. The method for recovering nickel and cobalt from laterite nickel ore according to claim 1 or 6, wherein: In the step (3), the temperature of the synergistic pressure acid leaching is 245-260°C, the pressure of the synergistic pressure acid leaching is 4.0-5.0 MPa, the time of the synergistic pressure acid leaching is 50-100 min, and the oxygen introduction rate per kilogram of laterite nickel ore is 2-2.5 Nm 3 , leaching until 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, wherein: 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, wherein: In the step (4), the neutralization reaction temperature is 80-90° C., and the neutralization reaction time is 1.5-3 h.

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

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