A method for enriching nickel and cobalt by low-carbon reduction, sulfidation and roasting of laterite nickel ore

Abstract

A method for enriching nickel and cobalt by low-carbon reduction, sulfidation, and roasting of laterite nickel ore comprises the following steps: drying, presulfidation, and crushing: drying, presulfiding, and crushing the laterite nickel ore into laterite nickel ore powder; roasting: roasting the laterite nickel ore powder with a reducing agent and a sulfiding agent in a roasting furnace to produce roasted sand and flue gas; fine grinding: grinding the roasted sand into a fine roasted sand powder; and flotation: separating the metal sulfides and gangue components in the roasted sand fine powder through a flotation process. The present invention replaces carbonaceous reducing agents and fuels with hydrogen, avoiding the production of carbon dioxide during the smelting process. The roasting flue gas is recycled, increasing hydrogen and sulfur utilization and reducing flue gas processing volume. Flotation is used to separate valuable metal sulfides and gangue components, avoiding the high-temperature melting of the laterite nickel ore to form matte and slag, thereby reducing energy consumption. The flotation nickel concentrate, with a grade of 10-30%, can be used as cold material for nickel matte blowing to regulate the heat balance of nickel matte blowing. The present invention offers the advantages of cleanliness, low energy consumption, and high efficiency.

Description

Technical Field

[0001] The present invention relates to a method for utilizing laterite nickel ore, and in particular to a method for enriching nickel and cobalt by reducing, sulfiding and roasting laterite nickel ore. Background Art

[0002] Nickel and cobalt energy metals are important raw materials for batteries, and their extraction processes and technologies are becoming key areas of future competition. Due to the lack of breakthroughs in nickel sulfide ore exploration, the deterioration of traditional mining resources, and the continued decline in the supply of high-quality nickel sulfide ore, laterite nickel ore resources have become an increasingly important raw material for nickel extraction. Laterite nickel ore is primarily composed of nickel, iron, and cobalt oxides, as well as gangue components such as silicon dioxide, calcium oxide, and magnesium oxide. The valuable metals in laterite nickel ore are oxides, making them difficult to concentrate through flotation. Metallurgical techniques are required to separate the gangue components from the valuable metals.

[0003] Conventional processing processes for laterite nickel ore can be broadly categorized into hydrometallurgy (bioleaching, high-pressure acid leaching, atmospheric-pressure ammonia leaching, etc.) and pyrometallurgy (RKEF, blast furnace smelting, reduction-sulfidation smelting of nickel matte, etc.). The pyrometallurgical process for laterite nickel ore requires the use of carbonaceous fuels and reducing agents to convert metal oxides into sulfides that enter the matte, while gangue components enter the slag. This results in high energy consumption and significant carbon dioxide emissions. The hydrometallurgical process, on the other hand, converts metal oxides into sulfates that enter the leachate, from which the metals are then separated. This process is lengthy, requires significant equipment investment, and produces large amounts of solid waste, including leaching residue.

[0004] CN 114540612 A discloses a pyrolysis-sulfidation beneficiation method for laterite nickel ore, as well as metal sulfides and their applications. The method comprises the following steps: S1) optionally drying the laterite nickel ore to obtain dry laterite nickel ore; S2) heating the dry laterite nickel ore with a sulfiding agent to react to obtain a sulfide mixed ore; S3) crushing and grinding the sulfide mixed ore to obtain fine ore, which is then fed to a beneficiation process to separate the metal sulfides and remaining tailings. This method involves drying the laterite nickel ore to remove free water, then adding a sulfiding agent and heating together to convert the nickel-cobalt oxides in the laterite nickel ore into sulfides. The method then utilizes currently established nickel-cobalt sulfide flotation technology to enable beneficiation of the laterite nickel ore under certain conditions, thereby reducing the amount of slag formed by gangue in downstream smelting processes. This method involves sulfiding dried laterite nickel ore, which requires simultaneous operation under high oxygen potential and high sulfur potential conditions. When there is a lack of reducing agent in the system, the SO2 partial pressure in the sulfidation reaction atmosphere must exceed 1atm. The reaction conditions are relatively harsh and the sulfidation efficiency is low.

[0005] CN 111635997 A discloses a method for smelting nickel-iron alloy by directly reducing and smelting laterite nickel ore using hydrogen: S1: mixing the laterite nickel ore with a flux and water to obtain a raw material mixture; S2: granulating the raw material mixture to obtain pellets with a particle size of less than 1 cm; S3: drying the pellets; S4: adding the dried pellets to an electric arc furnace and introducing hydrogen for reduction smelting to obtain a nickel-iron alloy melt, which is then cooled to obtain the nickel-iron alloy. This method eliminates the need for a pre-reduction and roasting step of the laterite nickel ore and directly performs liquid-phase reduction smelting to obtain a nickel-iron alloy with a high nickel content, simplifying the processing process and reducing energy consumption. Using hydrogen for reduction smelting, the resulting water vapor is directly volatilized, resulting in a high nickel grade of the nickel-iron alloy, reaching a nickel grade of over 18.86%. This method uses hydrogen to reduce laterite nickel ore to produce nickel-iron alloy. To obtain a molten metal, the reaction temperature is as high as 1400-1650°C and the energy consumption is high. The nickel-iron alloy product is suitable for the production of low-value products such as stainless steel. If the nickel-iron alloy is to be converted into nickel-iron sulfide for the manufacture of nickel sulfate and cobalt sulfate required for new energy vehicle batteries, it needs to be reheated, melted, and sulfurized for transformation, which is a long process and high energy consumption.

[0006] Therefore, it is urgent to develop a new processing technology for laterite nickel ore to achieve clean, short-process and efficient processing of laterite nickel ore. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a low-energy method for enriching nickel and cobalt by low-carbon reduction sulfidation roasting of laterite nickel ore.

[0008] The technical solution adopted by the present invention to solve the technical problem is as follows: a method for enriching nickel and cobalt by low-carbon reduction, sulfidation and roasting of laterite nickel ore, comprising the following steps:

[0009] (1) Drying, pre-sulfurization and crushing: drying, pre-sulfurizing and crushing the laterite nickel ore into laterite nickel ore powder;

[0010] (2) roasting: roasting the laterite nickel ore powder together with a reducing agent and a sulfiding agent in a roasting furnace to obtain roasted sand and flue gas;

[0011] (3) Fine grinding: Grind the roasted sand into fine powder; grinding allows the sulfide and gangue to be fully dissociated, facilitating flotation;

[0012] (4) Flotation: The metal sulfide and gangue components in the roasted sand fine powder are separated by flotation process.

[0013] Preferably, in step (1), particles smaller than 0.1 mm account for 50-90% of the laterite nickel ore powder, and the water content of the laterite nickel ore powder is ≤3 wt%.

[0014] Preferably, in step (2), the roasting method is fluidized roasting.

[0015] Preferably, in step (2), the reducing agent is hydrogen.

[0016] More preferably, in step (2), the amount of hydrogen used for roasting each ton of laterite nickel ore powder is 50-100m 3 .

[0017] Preferably, in step (2), the vulcanizing agent is sulfur.

[0018] More preferably, in step (2), the weight of sulfur is 10-30% of the weight of the laterite nickel ore powder.

[0019] Preferably, in step (2), the calcination temperature is 500-900° C., and the calcination time is 2-4 hours.

[0020] Roasting is the process of sulfiding the iron, nickel and cobalt metal oxides in the pellets into sulfides under the action of reducing agents and sulfiding agents, while the gangue minerals such as silicon dioxide, calcium oxide and magnesium oxide remain unchanged, generating roasted sand and flue gas. The main reactions of roasting are as follows:

[0021] Fe2O3+H2(g)=2FeO+H2O(g) (1)

[0022] FeO+H2(g)=Fe+H2O(g) (2)

[0023] NiO+H2(g)=Ni+H2O(g) (3)

[0024] CoO+H2(g)=Co+H2O(g) (4)

[0025] 2Fe+S2(g)=2FeS (5)

[0026] 3Ni+S2(g)=Ni3S2 (6)

[0027] 9Co+4S2(g)=Co9S8 (7)

[0028] 4FeO+3S2(g)=4FeS+2SO2(g) (8)

[0029] H2(g)+S2(g)=H2S(g) (9)

[0030] Preferably, the flue gas obtained in step (2) is returned to step (1) to participate in drying and pre-sulfurization.

[0031] The flue gas obtained in step (2) is a high-temperature reducing sulfur-containing flue gas containing components such as SO2 and H2S. Returning to step (1), the waste heat can be used to remove moisture from the laterite nickel ore, and at the same time, the laterite nickel ore is pre-reduced and pre-sulfurized, thereby improving the utilization rate of the reducing agent and the sulfiding agent and reducing the roasting flue gas processing volume. The main reactions are as follows:

[0032] FeO+H2S(g)=FeS+H2O(g) (10)

[0033] 9NiO+7H2S(g)=3Ni3S2+7H2O(g)+SO2(g) (11)

[0034] 27CoO+25H2S(g)=3Co9S8+25H2O(g)+SO2(g) (12)

[0035] Preferably, the proportion of particles with a particle size of less than 0.074 mm in the roasted sand fine powder is greater than 70%.

[0036] Preferably, in step (4), the reagent used in the flotation is one or more of butyl xanthate, butylamine black medicine, BK303, and thiamine ester.

[0037] Preferably, in step (4), the dosage of the reagent used in the flotation is 30-100 g / t.

[0038] The concentrate foam obtained by flotation is metal sulfide, i.e. nickel concentrate, and the tailings are gangue components.

[0039] The present invention performs a coordinated reduction and sulfidation on dried laterite nickel ore. From a thermodynamic perspective, reduction and sulfidation proceed simultaneously, first reducing some oxides to elemental metals, which then combine with a sulfiding agent to form sulfides. This significantly reduces the oxygen potential of the reaction system, making reaction conditions easier to achieve and improving sulfidation efficiency. The present invention proposes a coordinated reduction and sulfidation process for laterite nickel ore. This process can achieve sulfidation transformation of nickel, cobalt, and iron metal oxides in the laterite nickel ore at relatively low temperatures, and separates sulfides from gangue components through flotation. This process is simple, low-cost, and the metal sulfide products directly connect to the new energy industry, resulting in high value.

[0040] In the present invention, laterite nickel ore is dried and crushed to obtain laterite nickel ore powder; the laterite nickel ore powder is reduced with hydrogen and sulfurized in a fluidized bed, thereby converting the nickel, cobalt, and iron oxides in the laterite nickel ore into nickel, cobalt, iron sulfides and flue gas; finally, flotation is used to separate the sulfides in the roasted sand from gangue components such as silicon, calcium, and magnesium to obtain nickel sulfide concentrate and tailings. The present invention uses hydrogen as a reducing agent to convert nickel, cobalt, and iron into sulfide in a solid phase state, and uses flotation to separate sulfides from gangue components, thereby avoiding the high-temperature smelting and slag-making processes of traditional laterite nickel ore smelting methods. This method uses non-carbonaceous cleaning, low processing temperature, simple process, low energy consumption, and no carbon emissions, thus achieving clean, low-consumption, and short-process processing of laterite nickel ore.

[0041] Beneficial effects of the present invention:

[0042] The present invention addresses the shortcomings of laterite nickel flotation, such as the difficulty in flotation, high energy consumption, and high pollution in conventional metallurgical processes, and proposes a new method for reduction roasting, sulfidation transformation, and flotation separation. Hydrogen is used instead of carbonaceous reducing agents and fuels to avoid the generation of carbon dioxide during the smelting process. The roasting flue gas is recycled, which improves the utilization rate of hydrogen and sulfur and reduces the amount of flue gas to be treated. The flotation method is used to separate the valuable metal sulfides and gangue components, avoiding the high-temperature melting of laterite nickel ore to form matte and slag, thereby reducing energy consumption. The flotation nickel concentrate has a grade of 10-30% and can be used as cold material for nickel matte blowing to adjust the heat balance of nickel matte blowing. The present invention has the advantages of being clean, low-consumption, and highly efficient. DETAILED DESCRIPTION

[0043] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] The raw materials used in the examples of the present invention were all obtained through conventional commercial channels.

[0045] Example 1

[0046] Take 1 kg of laterite nickel ore, and its mineral composition is NiO, CoO, Fe2O3, and H2O with mass percentages of 2.03%, 0.13%, 35.71%, and 32.76%, respectively.

[0047] The method for enriching nickel and cobalt by low-carbon reduction and sulfidation roasting of laterite nickel ore in this embodiment comprises the following steps:

[0048] (1) Drying, pre-sulfurization, and crushing: drying the laterite nickel ore to a water content of 3 wt %, introducing a high-temperature sulfur-containing gas for pre-sulfurization, and then crushing the ore into particles with a size of less than 0.1 mm, accounting for 80%, to obtain laterite nickel ore powder;

[0049] (2) Calcination: Add laterite nickel ore powder into a fluidized bed calciner, inject hydrogen at a rate of 500 mL / min (a total of 90 L of hydrogen), add 200 g of sulfur, control the calcination temperature at 500° C., and calcine for 3 h to obtain calcine and flue gas;

[0050] (3) Fine grinding: grinding the calcined sand until the particles with a particle size of less than 0.074 mm account for 80% to obtain calcined sand fine powder;

[0051] (4) Flotation: The roasted sand fine powder is subjected to a two-coarse three-fine three-sweep flotation process to separate the metal sulfide and gangue components. The flotation agent used is butyl xanthate, and the amount of agent used for each flotation is 30-100g / t. The obtained metal sulfide is nickel concentrate. The nickel content in the nickel concentrate is 10%, the Co content is 0.8%, the Ni recovery rate is 90%, and the Co recovery rate is 89%.

[0052] The flue gas obtained in step (2) is returned to step (1) to participate in drying and pre-sulfurization.

[0053] Example 2

[0054] Take 5 kg of laterite nickel ore, whose mineral composition is NiO, CoO, Fe2O3, and H2O with mass percentages of 2.03%, 0.13%, 35.71%, and 32.76% respectively.

[0055] The method for enriching nickel and cobalt by low-carbon reduction and sulfidation roasting of laterite nickel ore in this embodiment comprises the following steps:

[0056] (1) Drying, pre-sulfurization, and crushing: a high-temperature sulfur-containing gas is introduced into the laterite nickel ore to dry and pre-sulfurize the laterite nickel ore until the pre-sulfurized moisture content is less than 3 wt %, and then the ore is crushed into particles with a size of less than 0.1 mm, accounting for 90%, to obtain laterite nickel ore powder;

[0057] (2) Calcination: The pellets were added into a fluidized bed calciner, with a hydrogen injection rate of 100 L / h (a total of 300 L of hydrogen), a sulfur addition amount of 0.5 kg, a calcination temperature of 700° C., and a calcination time of 3 h to obtain calcine and flue gas;

[0058] (3) Fine grinding: grinding the calcined sand until the particles with a particle size of less than 0.074 mm account for 85% to obtain calcined sand fine powder;

[0059] (4) Flotation: The roasted sand fine powder is subjected to a two-coarse three-fine three-sweep flotation process to separate the metal sulfide and gangue components. The flotation agent used is butylamine black medicine. The amount of the agent used for each flotation is 30-100g / t. The obtained metal sulfide is nickel concentrate. The nickel concentrate has a Ni content of 20% and a Co content of 0.2%. The Ni recovery rate is 92% and the Co recovery rate is 90%.

[0060] The flue gas obtained in step (2) is returned to step (1) to participate in drying and pre-sulfurization.

[0061] Example 3

[0062] Take 10 kg of laterite nickel ore, whose mineral composition is NiO, CoO, Fe2O3, and H2O with mass percentages of 2.03%, 0.13%, 35.71%, and 32.76%, respectively.

[0063] The method for enriching nickel and cobalt by low-carbon reduction and sulfidation roasting of laterite nickel ore in this embodiment comprises the following steps:

[0064] (1) Drying, pre-sulfurization, and crushing: The high-temperature sulfur-containing flue gas obtained from the previous production batch is introduced into the laterite nickel ore to dry and pre-sulfurize the laterite nickel ore until the moisture content of the laterite nickel ore is less than 3 wt%, and then the laterite nickel ore is crushed into particles with a size of less than 0.1 mm, accounting for 60%, to obtain laterite nickel ore powder;

[0065] (2) Calcination: The pellets were added into a fluidized bed calciner, with a hydrogen injection rate of 350 L / h (a total of 700 L of hydrogen), a sulfur addition amount of 2.5 kg, a calcination temperature of 900° C., and a calcination time of 2 h to obtain calcine and flue gas;

[0066] (3) Fine grinding: grinding the calcined sand until the particles with a particle size of less than 0.074 mm account for 70% to obtain calcined sand fine powder;

[0067] (4) Flotation: The roasted sand fine powder is subjected to a two-coarse, three-fine, and three-sweep flotation process to separate the metal sulfide and gangue components. The flotation agent used is thiamine ester, and the amount of the agent used for each flotation is 30-100g / t. The obtained metal sulfide is nickel concentrate. The nickel content in the nickel concentrate is 15%, the Co content is 1%, the Ni recovery rate is 88%, and the Co recovery rate is 86%.

[0068] The flue gas obtained in step (2) is returned to step (1) to participate in drying and pre-sulfurization.

Claims

1. A method for enriching nickel and cobalt by low-carbon reduction, sulfidation and roasting of laterite nickel ore, characterized in that: The following steps are involved: (1) Drying, pre-sulfurization and crushing: drying, pre-sulfurizing and crushing the laterite nickel ore into laterite nickel ore powder; (2) Calcination: The laterite nickel ore powder is calcined together with a reducing agent and a sulfiding agent in a calcining furnace to obtain calcined sand and flue gas; the reducing agent is hydrogen; the sulfiding agent is sulfur; the calcination method is fluidized bed calcination; the calcination temperature is 500-900°C; the flue gas obtained is returned to step (1) to participate in drying and pre-sulfurization; (3) Fine grinding: Grind the roasted sand into fine powder; (4) Flotation: The metal sulfide and gangue components in the roasted sand fine powder are separated by flotation process.

2. The method for enriching nickel and cobalt by low-carbon reduction, sulfidation and roasting of laterite nickel ore according to claim 1, characterized in that: In step (1), particles smaller than 0.1 mm account for 50-90% of the laterite nickel ore powder, and the water content of the laterite nickel ore powder is less than 3 wt%.

3. The method for enriching nickel and cobalt by low-carbon reduction, sulfidation and roasting of laterite nickel ore according to claim 1 or 2, characterized in that: In step (2), the amount of hydrogen used for roasting each ton of laterite nickel ore powder is 50-100m 3 The weight of sulfur is 10-30% of the weight of the laterite nickel ore powder.

4. The method for enriching nickel and cobalt by low-carbon reduction, sulfidation and roasting of laterite nickel ore according to any one of claims 1 to 3, characterized in that: In step (2), the roasting time is 2 to 4 hours.

5. The method for enriching nickel and cobalt by low-carbon reduction, sulfidation and roasting of laterite nickel ore according to any one of claims 1 to 4, characterized in that: In step (3), the proportion of particles with a particle size of less than 0.074 mm in the roasted sand fine powder is greater than 70%.

6. The method for enriching nickel and cobalt by low-carbon reduction, sulfidation and roasting of laterite nickel ore according to any one of claims 1 to 5, characterized in that: In step (4), the reagent used for flotation is one or more of butyl xanthate, butylamine black medicine, BK303, and thiamine ester.

7. The method for enriching nickel and cobalt by low-carbon reduction, sulfidation and roasting of laterite nickel ore according to claim 6, characterized in that: In step (4), the dosage of the reagent used in the flotation is 30-100 g / t.