All-component comprehensive utilization method of limonite type laterite-nickel ore

Abstract

The invention discloses an all-component comprehensive utilization method for limonite type laterite-nickel ore, and belongs to the technical field of mineral processing and metallurgy. According to the method, multi-stage preheating and selective reduction are combined, accurate regulation and control of ore phase conversion are achieved by optimizing temperature and atmosphere conditions, metallic nickel and cobalt generated through reduction form a stable complex in the ammonia leaching process, and magnetite serves as an indissolvable magnetic phase to be left in slag. The reaction temperature is effectively reduced, the energy consumption is reduced, and the gas-solid mass transfer efficiency and the heat transfer efficiency are remarkably improved. The mineral structure is regulated and controlled through selective reduction, the adverse effects of excessive reduction, sintering, follow-up leaching difficulty and the like of iron oxide in the high-temperature roasting process of a traditional rotary kiln are avoided, and efficient selective leaching of nickel and cobalt and recovery and enrichment of magnetic iron ore are achieved. And meanwhile, the nickel and cobalt leaching efficiency is remarkably improved, interference of iron impurities on a leaching solution is reduced, and an economical and feasible new technical path is provided for resource comprehensive utilization and green metallurgy development of the limonite type laterite-nickel ore.

Description

Technical Field

[0001] The invention belongs to the technical field of mineral processing and metallurgy, and in particular relates to a method for comprehensive utilization of all components of limonitic laterite nickel ore. Background Art

[0002] Nickel is a strategic metal widely used in defense, aerospace, and energy sectors. It is a key raw material for the production of stainless steel, nickel-based plating materials, and power batteries. By 2024, global nickel reserves exceeded 130 million tons, of which 54% comprised laterite nickel ore, 35% comprised sulfide nickel ore, and the remaining 11% comprised of seabed minerals. With the gradual depletion of sulfide nickel ore resources and the continuous rise in nickel demand, laterite nickel ore has become a primary target for nickel resource development. However, laterite nickel ores can be categorized as serpentine-type and limonite-type based on their primary mineral composition. Limonite-type laterite nickel ore is characterized by high iron content and low nickel content, and its efficient and comprehensive utilization remains a significant challenge. Existing laterite nickel ore processing techniques primarily include rotary kiln drying, pre-reduction, and electric furnace smelting (RKEF) and high-pressure acid leaching (HPAL). The RKEF process is suitable for serpentine-type laterite nickel ore. Its characteristic process involves rotary kiln drying and pre-reduction followed by direct electric furnace smelting to produce nickel-iron alloys. However, the RKEF process is less adaptable to limonitic laterite nickel ores with high iron content. During the smelting process, a large amount of iron resources are converted into waste slag, making it impossible to effectively recover iron resources. In addition, the pre-reduction and smelting processes require high energy consumption, which increases production costs. The HPAL process is mainly targeted at limonitic laterite nickel ores. Limonitic laterite nickel ores can effectively recover nickel and cobalt by leaching sulfuric acid under high temperature and high pressure conditions, and form nickel-cobalt hydroxide precipitates (MHP). In summary, the existing RKEF and HPAL processes have not yet taken into account the efficient utilization of iron resources and the green and low-carbon process requirements, which has restricted the comprehensive resource development of limonitic laterite nickel ores.

[0003] Patent CN117385174A discloses a method for purifying laterite nickel ore. This method uses high-temperature and high-pressure sulfuric acid leaching on limonitic laterite nickel ore. After leaching, an oxidizing slurry rich in high-valent cobalt and manganese oxides is introduced to replace compressed air to oxidize divalent iron to trivalent iron. The selective precipitation and separation of iron, aluminum, and scandium is achieved by regulating the pH. The aluminum-scandium slag enters the subsequent extraction process, while the nickel and cobalt remain in the solution and are further neutralized and precipitated to form a nickel-cobalt hydroxide product (MHP). The nickel-cobalt slurry in the tailings is oxidized and recycled for the front-end reaction to reduce oxidant consumption. Although this process reduces oxidant consumption through a cyclic oxidation process, its high-temperature and high-pressure operation significantly increases equipment investment and energy consumption. In addition, iron resources are not effectively recovered, and acidic tailings are directly discharged, which not only wastes resources but also poses a pollution risk to the environment. Patent CN106086469A discloses a method for extracting nickel oxide from laterite nickel ore. First, the laterite nickel ore is subjected to direct reduction-grinding and magnetic separation to obtain nickel iron powder. The nickel iron powder is then subjected to selective oxidation and roasting. Taking advantage of the greater affinity of iron for oxygen than nickel, the metallic iron is oxidized to Fe3O4. During the selective oxidation and roasting, the metallic nickel is not oxidized. The roasted product is then subjected to an ammonia leaching-ammonia distillation-calcination process to obtain a nickel oxide product. The nickel recovery rate can reach over 90%, achieving efficient nickel recovery. However, this method has a long process flow, involving multiple steps such as pelletizing, high-temperature reduction-grinding-magnetic separation, reoxidation, ammonia leaching-ammonia distillation-calcination, etc. The process is lengthy and the operation is complicated. The equipment investment and operating costs are significantly increased. The reduction temperature is as high as 1250℃ to 1320℃, which consumes a lot of energy and has a high production cost, which seriously restricts the industrial application of this process. While the aforementioned methods have made significant progress in improving nickel and cobalt recovery efficiency, with nickel and cobalt recovery rates exceeding 90%, and exhibiting advantages in energy-saving recycling and impurity separation, they still suffer from numerous technical drawbacks: First, the high iron content in the leaching residue prevents effective iron recovery, resulting in resource waste. Second, the harsh operating conditions of high temperature and high pressure significantly increase equipment investment and operating energy consumption. Third, the direct discharge of untreated acidic tailings increases the difficulty of waste treatment and poses an environmental risk. Furthermore, scaling in the sulfuric acid medium seriously impacts system stability, further reducing system availability and accelerating equipment wear.

[0004] Therefore, there is an urgent need to develop a low-temperature, low-pressure, and process-simplified method for the comprehensive utilization of all components of limonitic laterite nickel ore. By optimizing the process flow and regulating the reaction conditions, while achieving effective recovery of nickel and cobalt, it is possible to take into account the efficient recovery of iron resources and the reduction of acidic tailings, thereby improving the comprehensive utilization rate of resources and reducing the environmental load. Summary of the Invention

[0005] Aiming at the problems of long process flow, low iron resource recovery rate and acidic tailings discharge in the existing limonitic laterite nickel ore processing process, the present invention proposes a technically feasible and economically reasonable method for comprehensive utilization of all components of limonitic laterite nickel ore through selective reduction-ammonia leaching-magnetic separation.

[0006] To achieve the above object, the present invention adopts the following scheme:

[0007] A method for comprehensive utilization of all components of limonitic laterite nickel ore comprises the following steps:

[0008] Step 1. crushing the limonitic laterite nickel ore;

[0009] Step 2. The crushed laterite nickel ore is sequentially passed through a primary cyclone preheater and a secondary cyclone preheater for preheating and drying to obtain a preheated material;

[0010] Step 3. The preheated material is fed into the main suspension roasting furnace, where it is suspended under the action of high-temperature flue gas and heated to further remove bound water to obtain a heated material; the high-temperature flue gas temperature is 600°C to 900°C;

[0011] Step 4. The heated material is subjected to a primary gas-solid separation. The separated solid material undergoes a reduction reaction under the action of the reducing gas. After the reaction is completed, a secondary gas-solid separation is performed to obtain the reduced material and excess reducing gas;

[0012] Step 5. After the reduced material is quenched with water and cooled, a mixed solution of ammonia water and ammonium salt is added to perform ammonia leaching at normal pressure. The slurry obtained after leaching is filtered to obtain nickel-cobalt leaching solution and ammonia leaching residue;

[0013] Step 6. The ammonia leached residue is ball-milled and then subjected to weak magnetic separation to obtain iron concentrate and magnetic separation tailings.

[0014] In the above step 2, the crushed limonitic laterite nickel ore is subjected to two-stage preheating and drying treatment in sequence; the preheating temperature is controlled at 300°C to 450°C and is divided into two stages:

[0015] The temperature of the first-stage cyclone preheater is 300℃~350℃. The free water in the ore particles is first vaporized and discharged to achieve preliminary drying. The main reaction formula of this process is:

[0016] H2O (l) = H2O (g) (1)

[0017] The temperature of the secondary cyclone preheater is 350℃~450℃, the crystal water in the ore is further decomposed, and part of the goethite is converted into hematite (Fe2O3), accompanied by the release of water vapor. The main reaction formula of this process is:

[0018] 2FeO(OH) = Fe2O3 + H2O (2)

[0019] In the above step 2, during the preheating and drying process, the crushed laterite nickel ore material enters the first cyclone preheater and the second cyclone preheater in sequence with the air flow under negative pressure, wherein the ratio of the air volume flow rate to the mass flow rate of the crushed laterite nickel ore is controlled at 0.10m 3 / kg~0.30m 3 / kg to ensure sufficient gas-solid contact and optimize heat transfer. By properly controlling the temperature and gas flow ratio, the moisture in the mineral is gradually removed, creating a suitable physical and chemical environment for the subsequent reduction reaction.

[0020] In the above step 3, the preheated material enters the main suspension roasting furnace, and the air and gas introduced from the bottom of the furnace are burned to generate high-temperature flue gas to heat the suspended material, and the obtained heated material temperature is 650℃~700℃.

[0021] In step 4 above, the heated material undergoes a primary gas-solid separation, and the resulting high-temperature flue gas enters a multi-stage cyclone preheater for heat recovery. The resulting solid material undergoes a reduction reaction with the reducing gas, followed by a secondary gas-solid separation to produce reduced material and excess reducing gas. The excess reducing gas is then used to preheat the main suspension roasting furnace. This staged preheating method allows the high-temperature gas to exchange heat with the cooler material in a step-by-step manner, maximizing flue gas waste heat recovery and achieving gradient utilization and efficient transfer of thermal energy.

[0022] In the above step 4, the solid material enters the reduction reaction stage under the action of gravity, the reducing gas is introduced, the reduction temperature is regulated to 500° C. to 600° C., and the reaction time is controlled to 15 min to 30 min.

[0023] In the above step 4, the reducing gas is a mixed gas of hydrogen (H2), carbon monoxide (CO) and nitrogen (N2). The gas flow rate is 0.10m 3 / kg~0.40m 3 / kg. The reducing gas, measured by volume, has a combined H2 and CO concentration of 20% to 40%, including 15% to 25% H2 and 5% to 15% CO. The remainder, N2, is used for gas dilution and fluidization stabilization to ensure the reducing properties of the reaction atmosphere. After the reduction reaction is complete, the material is discharged with the airflow, and the unreacted reducing gas is separated and recycled back to the preceding heating system as fuel, achieving a closed-loop utilization of gas resources.

[0024] In the above step 4, the main chemical reaction formula of the reduction reaction is as follows:

[0025] 3Fe2O3 + CO / H2 = 2Fe3O4 + CO2 / H2O (3)

[0026] CoO + CO / H2 = Co + CO2 / H2O (4)

[0027] NiO + CO / H2 = Ni + CO2 / H2O (5)

[0028] In the above step 5, air is introduced after the atmospheric pressure ammonia leaching reaction for 30 minutes, and the air flow rate is controlled at 1.0 L / min-3.0 L / min.

[0029] In the above step 5, the ammonium salt is at least one of ammonium sulfate, ammonium carbonate, and ammonium bicarbonate.

[0030] In the above step 5, the liquid-to-solid ratio of the mixed solution to the reducing material is (2-4): 1 mL / g.

[0031] In the above step 5, the normal pressure ammonia leaching reaction time is 60 min to 120 min; the stirring speed is 200 r / min to 600 r / min, and the pH value of the slurry is 9.5 to 11.5.

[0032] In the above step 5, the main reaction formula of the ammonia leaching reaction is:

[0033] 2Ni + O2 + 2(n-2)NH3 + 2(NH4)2CO3 = 2[Ni(NH3) n ]CO3+2H2O (6)

[0034] 2Co + O2 + 2(n-2)NH3+2(NH4)2CO3 = 2[Co(NH3) n ]CO3+2H2O (7)

[0035] 4[Co(NH3) n ] 2+ + O2+4NH 4+ = 4[Co(NH3) n ] 3+ + 4NH3+2H2O (8)

[0036] The basic principle of the present invention is that, in response to the problem that the components of limonitic laterite nickel ore are complex and difficult to separate, a method is proposed, which includes multi-stage cyclone preheating and drying, fluidized selective reduction roasting, atmospheric pressure ammonia leaching and wet magnetic separation recovery, to achieve efficient and coordinated recycling of all components of nickel, cobalt and iron. In the preheating and fluidized reduction roasting stages, multi-stage fluidized drying and dehydration effectively removes moisture from the ore, thereby improving the efficiency of the reduction reaction; through precise control of the reaction atmosphere during the fluidized selective reduction process, iron oxides such as goethite (FeO(OH)) are selectively reduced to artificial magnetite (Fe3O4) with strong magnetism and not easily soluble in ammonia water, avoiding over-reduction to metallic iron and ensuring the magnetic stability of the Fe3O4 ore phase. At the same time, nickel and cobalt oxides are reduced to a metallic state, and the nickel-cobalt metallization rate can reach more than 95%, providing an active reaction material state basis for the selective complexation of nickel and cobalt in subsequent ammonia leaching. In the ammonia leaching stage, an ammonia water / ammonium salt mixed system is used, and under suitable pH conditions, metallic nickel and cobalt are respectively complexed with ammonia to form Ni(NH3)6 2+ With Co(NH3)3 2+ The complex enters the solution, while Fe3O4 does not participate in the complex reaction and is stably retained in the leaching residue, thereby achieving effective separation of nickel, cobalt and iron, reducing the interference of iron impurities on the leachate, and enhancing the selective extraction efficiency of nickel and cobalt; in the magnetic separation stage, the magnetite Fe3O4 in the ammonia leaching residue can be efficiently enriched by adjusting the magnetic field intensity to produce magnetic iron concentrate, which can be used as a raw material for ironmaking; the magnetic separation tailings can be used as an auxiliary raw material for cement production due to their stable chemical properties and environmental friendliness, realizing high-value recovery of iron resources and resource utilization of tailings.

[0037] Compared to existing high-pressure acid leaching processes for treating limonitic laterite nickel ore, the present invention combines graded preheating with selective reduction to effectively lower reaction temperatures, reduce energy consumption, and significantly improve gas-solid mass and heat transfer efficiency. This process optimizes temperature and atmosphere distribution to selectively reduce iron oxides to magnetic Fe₃O₄, maintaining the stability of the magnetic ore phase. This effectively avoids the adverse effects of excessive reduction of iron oxides to metallic iron during traditional high-temperature rotary kiln roasting, enabling precise control of ore phase transformation. The reduced metallic nickel and cobalt undergo a complexation reaction during ammonia leaching, significantly improving nickel and cobalt leaching efficiency. Meanwhile, magnetite remains in the slag as an insoluble magnetic phase, reducing interference from iron impurities in the leachate. Through selective reduction, the selective leaching of nickel and cobalt and the enrichment of magnetic iron ore are mutually promoted, effectively avoiding the risks of difficult temperature control and excessive reduction of iron oxides during rotary kiln roasting. Furthermore, this method boasts high energy efficiency, enabling waste heat recovery and recycling of excess reducing gas, creating a closed-loop energy and tail gas resource system, effectively reducing production energy consumption and costs. Through the coordinated optimization of multi-stage reaction paths, the mineral structure regulation and step-by-step recovery were strengthened, and a systematic recovery process path for nickel, cobalt and iron resources was formed, providing an economically feasible new technology path for the comprehensive resource utilization and green metallurgical development of limonitic laterite nickel ore. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The present invention is a schematic diagram of the process flow of a method for comprehensive utilization of all components of limonitic laterite nickel ore. DETAILED DESCRIPTION

[0039] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments. Those skilled in the art should understand that the embodiments are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0040] To further describe the present invention, the method of the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0041] The low-grade limonitic laterite nickel ore used in the embodiments of the present invention has a Ni grade of 0.5% to 1.3%, contains TFe 40% to 50% by weight, Co 0.1% to 0.3%, SiO2 4% to 12.5%, Al2O3 5% to 13%, CaO 0.25% to 6%, MgO 0.5% to 5%, and contains ≤15% water.

[0042] In the embodiment of the present invention, the multi-stage cyclone preheating temperature is controlled at 300°C to 450°C, and the reduction temperature is maintained at 650°C to 700°C.

[0043] The reducing gas in the embodiment of the present invention is a mixed gas of H2, CO and nitrogen.

[0044] In the embodiment of the present invention, the ammonia leaching reaction system adopts an ammonia water-ammonium sulfate solution, and the required oxygen source is the air.

[0045] Example 1:

[0046] A comprehensive utilization method of all components of limonitic laterite nickel ore, the process flow chart of which is as follows Figure 1 The specific operation method is as follows:

[0047] Step 1. Place limonitic laterite nickel ore in a silo for crushing. The limonitic laterite nickel ore has a Ni grade of 0.53% and contains, by weight, 44.05% TFe, 0.14% Co, 4.74% SiO2, 10.23% Al2O3, 5.68% CaO, and 1.75% MgO. The crushed laterite nickel ore has a solid particle size of ≤1.5 mm, of which the particle size less than 0.074 mm accounts for 45% of the total mass and contains 12.66% water by mass.

[0048] Step 2: Feed the laterite nickel ore in the silo into the multi-stage cyclone preheating and drying system through a screw feeder. The ratio of the gas volume flow rate of the cyclone preheating system to the mass flow rate of the mixed material is 0.10m 3 / kg; start the Roots blower to form a negative pressure in the bag dust collector, cyclone dust collector, first-level cyclone preheater, second-level cyclone preheater, suspension roasting main furnace, and high-temperature separation cyclone; under negative pressure conditions, the material is fed into the first-level cyclone preheater to be preheated to 300°C to obtain first-level preheated material, and the first-level preheated material is then fed into the second-level cyclone preheater to be preheated to 350°C to obtain second-level preheated material.

[0049] Step 3. The secondary preheating material enters through the feed port at the bottom of the suspension roasting main furnace, and air and gas are introduced from the bottom of the roasting main furnace. Under the action of high-temperature flue gas and negative pressure generated by combustion, the secondary preheating material is in a suspended state in the suspension roasting main furnace and is further heated to 650°C to obtain heated material.

[0050] Step 4. The heated material follows the airflow from the discharge pipe at the top of the suspended main furnace into the high-temperature separation cyclone; after gas-solid separation, the heated material enters the fluidized reduction reactor under the action of gravity, and the high-temperature flue gas enters the secondary cyclone preheater. A nitrogen and coal gas mixture is introduced into the bottom of the reduction reactor. The solid material is in a fluidized motion state under the action of nitrogen and coal gas, and contacts the reducing gas in the fluidized reduction reactor for reduction reaction. The temperature of the material during the reduction reaction is 500°C, and the reaction time is 30 minutes; the ratio of the volume flow of the reducing gas entering the fluidized reduction reactor to the mass flow of the solid material is 0.40m 3 / kg. The total volume concentration of H2 and CO in the reducing gas is 40%, with H2 and CO at 25% and 15% respectively, and the remainder being N2. The reaction products flow out of the discharge port of the fluidized reduction reactor along with the airflow and enter the cyclone separator along with the airflow. After gas-solid separation, the reduced material and excess reduced gas are separated and enter the burner for further combustion.

[0051] Step 5. The reduced material enters a water quenching cooling pool, is cooled to room temperature by water quenching, and then enters a leaching tank. A mixed solution of ammonia water and ammonium sulfate system is configured, and the liquid-solid ratio with the solid reduced material is 3:1, the total ammonia concentration is 6 mol / L, the molar concentration ratio of ammonium ion to sulfate ion is 2:1, the stirring speed is 400r / min, and air is started after the reaction for 30min. The air flow rate is 1.5L / min, and the ammonia leaching reaction is carried out for 120min. After the reaction is completed, the slurry pH is measured to be 9.8. After the leaching is completed, the nickel-cobalt leachate and the leaching residue are filtered. The leaching rate of nickel is 96.22%, and the leaching rate of cobalt is 95.10%.

[0052] Step 6: After the leached residue is ground to a -0.074 mm content of 80%, magnetic separation is performed under a magnetic separator field intensity of 100 kA / m to obtain a magnetic concentrate with a TFe content of 55.49% and a recovery rate of 83.12%.

[0053] Example 2:

[0054] The process flow of this embodiment is the same as that of embodiment 1, except that:

[0055] Step 1. A limonitic laterite nickel ore having a Ni grade of 1.28%, containing by mass 49.82% TFe, 0.21% Co, 7.12% SiO2, 5.12% Al2O3, 0.25% CaO, and 0.73% MgO, wherein the particle size of the solid portion is ≤1.5 mm, of which the portion with a particle size less than 0.074 mm accounts for 50% of the total mass, and the water content is 14.61% by mass;

[0056] Step 2. The material temperature after preheating in the first-stage cyclone preheater is 350°C; the material temperature after preheating in the second-stage cyclone preheater is 450°C; the ratio of the gas volume flow rate of the multi-stage cyclone preheating system to the mass flow rate of the mixed material is 0.30m 3 / kg;

[0057] Step 3. The preheated material is further heated to 700°C in the main suspension roasting furnace;

[0058] Step 4. The temperature of the material during the reduction reaction in the reduction reactor is 600°C, and the reduction time is 15 minutes; the ratio of the volume flow rate of the reducing gas entering the reduction reactor to the mass flow rate of the solid material is 0.30m 3 / kg. The total volume concentration of H2 and CO in the reducing gas is 34%, the volume concentration of H2 is 22%, the volume concentration of CO is 12%, and the balance is N2;

[0059] Step 5. A mixed solution of aqueous ammonia and ammonium sulfate was prepared, with a liquid-to-solid ratio of 4:1 to the solid reducing material, a total ammonia concentration of 5 mol / L, a molar concentration ratio of ammonium to sulfate of 3:1, a stirring speed of 500 r / min, and air flow of 1.5 L / min after 30 minutes of reaction. The ammonia leaching reaction was carried out for 60 minutes. After the reaction, the slurry pH was measured to be 9.5, the nickel leaching rate was 95.88%, and the cobalt leaching rate was 94.63%;

[0060] Step 6: The leached residue was ground to a -0.074 mm particle size of 90%. Under a magnetic separation field strength of 150 kA / m, magnetic separation was performed to obtain a magnetic concentrate with a TFe content of 56.52% and a recovery rate of 82.11%.

[0061] Example 3:

[0062] The process flow of this embodiment is the same as that of embodiment 1, except that:

[0063] Step 1. The limonitic laterite nickel ore has a Ni grade of 1.17%, contains, by mass, 46.90% TFe, 0.26% Co, 12.01% SiO2, 5.01% Al2O3, 4.88% CaO, and 1.27% MgO. The particle size of the solid portion is ≤1.5 mm, of which the portion with a particle size less than 0.074 mm accounts for 55% of the total mass. The water content is 12.60% by mass.

[0064] Step 2. The material temperature after preheating in the first-stage cyclone preheater is 325°C; the material temperature after preheating in the second-stage cyclone preheater is 425°C. The ratio of the gas volume flow rate of the multi-stage cyclone preheating system to the mass flow rate of the mixed material is 0.20m 3 / kg;

[0065] Step 3. The preheated material is further heated to 680°C in the suspension roasting main furnace;

[0066] Step 4. The temperature of the material during the reduction reaction in the reduction reactor is 550°C, and the reduction time is 22 minutes; the ratio of the volume flow rate of the reducing gas entering the reduction reactor to the mass flow rate of the solid material is 0.25m 3 / kg. The total volume concentration of H2 and CO in the reducing gas is 30%, the volume concentration of H2 is 20%, the volume concentration of CO is 10%, and the balance is N2;

[0067] Step 5. A mixed solution of aqueous ammonia and ammonium sulfate was prepared, with a liquid-to-solid ratio of 5:1 to the solid reducing material, a total ammonia concentration of 7 mol / L, a molar concentration ratio of ammonium to sulfate of 4:1, a stirring speed of 600 r / min, and air flow of 1.5 L / min after 30 minutes of reaction. The ammonia leaching reaction was carried out for 100 minutes. After the reaction, the slurry pH was measured to be 11.5, the nickel leaching rate was 97.11%, and the cobalt leaching rate was 96.09%;

[0068] Step 6: The leached residue is ground to a -0.074 mm particle size of 85%. Under a magnetic separation field strength of 120 kA / m, magnetic separation is performed to obtain a magnetic concentrate with a TFe content of 55.97% and a recovery rate of 82.98%.

[0069] Example 4:

[0070] The process flow of this embodiment is the same as that of embodiment 1, except that:

[0071] Step 1. The limonitic laterite nickel ore has a Ni grade of 0.87%, contains, by mass, 42.59% TFe, 0.19% Co, 5.66% SiO2, 12.88% Al2O3, 0.98% CaO, and 3.88% MgO. The particle size of the solid portion is ≤1.5 mm, of which the portion with a particle size less than 0.074 mm accounts for 60% of the total mass. The water content is 13.42% by mass.

[0072] Step 2. The temperature of the material after preheating in the first-stage cyclone preheater is 350°C; the temperature of the material after preheating in the second-stage cyclone preheater is 450°C. The ratio of the gas volume flow rate of the multi-stage cyclone preheating system to the mass flow rate of the mixed material is 0.15m 3 / kg;

[0073] Step 3. The preheated material is further heated to 650°C in the suspension roasting main furnace;

[0074] Step 4. The temperature of the material during the reduction reaction in the reduction reactor is 580°C, and the reduction time is 18 minutes; the ratio of the volume flow rate of the reducing gas entering the reduction reactor to the mass flow rate of the solid material is 0.10m 3 / kg. The total volume concentration of H2 and CO in the reducing gas is 20%, the volume concentration of H2 is 15%, the volume concentration of CO is 5%, and the balance is N2;

[0075] Step 5. A mixed solution of aqueous ammonia and ammonium sulfate was prepared, with a liquid-to-solid ratio of 3:1 to the solid reducing material, a total ammonia concentration of 6 mol / L, a molar concentration ratio of ammonium to sulfate of 2:1, a stirring speed of 200 r / min, and air flow of 1.5 L / min after 30 minutes of reaction. The ammonia leaching reaction was carried out for 90 minutes. After the reaction, the slurry pH was measured to be 9.8, the nickel leaching rate was 94.88%, and the cobalt leaching rate was 93.92%;

[0076] Step 6: The leached residue is ground to a -0.074 mm particle size of 90%. Under a magnetic separation field strength of 200 kA / m, magnetic separation is performed to obtain a magnetic concentrate with a TFe content of 57.88% and a recovery rate of 81.23%.

[0077] While the embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to the embodiments described above. Various modifications may be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof may be combined with one another unless there is a conflict.

Claims

1. A method for comprehensive utilization of all components of limonitic laterite nickel ore, characterized in that: The following steps are involved: Step 1. crushing the limonitic laterite nickel ore; Step 2. The crushed laterite nickel ore is sequentially passed through a primary cyclone preheater and a secondary cyclone preheater for preheating and drying to obtain a preheated material; Step 3. The preheated material is fed into the main suspension roasting furnace, where it is suspended under the action of high-temperature flue gas and heated to further remove bound water to obtain a heated material; the high-temperature flue gas temperature is 600°C to 900°C; Step 4. The heated material is subjected to a primary gas-solid separation. The separated solid material undergoes a reduction reaction under the action of the reducing gas. After the reaction is completed, a secondary gas-solid separation is performed to obtain the reduced material and excess reducing gas; Step 5. After the reduced material is quenched with water and cooled, a mixed solution of ammonia water and ammonium salt is added to perform ammonia leaching at normal pressure. The slurry obtained after leaching is filtered to obtain nickel-cobalt leaching solution and ammonia leaching residue; Step 6. The ammonia leached residue is ball-milled and then subjected to weak magnetic separation to obtain iron concentrate and magnetic separation tailings.

2. The method for comprehensive utilization of all components of limonitic laterite nickel ore according to claim 1, characterized in that: In step 2, during the preheating and drying process, the crushed laterite nickel ore material enters the first-stage cyclone preheater and the second-stage cyclone preheater in sequence with the air flow under negative pressure, wherein the ratio of the air volume flow rate to the mass flow rate of the crushed laterite nickel ore is controlled at 0.10m 3 / kg~0.30m 3 / kg.

3. The method for comprehensive utilization of all components of limonitic laterite nickel ore according to claim 1, characterized in that: In step 2, the preheating and drying temperature is 300°C to 450°C.

4. The method for comprehensive utilization of all components of limonitic laterite nickel ore according to claim 3, characterized in that: Preheating and drying is divided into two stages, wherein the temperature in the first-stage cyclone preheater is 300℃~350℃, and the temperature in the second-stage cyclone preheater is 350℃~450℃.

5. The method for comprehensive utilization of all components of limonitic laterite nickel ore according to claim 1, characterized in that: In step 3, the air and gas introduced into the bottom of the suspension roasting main furnace are burned, and the high-temperature flue gas generated heats the suspended material, and the obtained heated material temperature is 650°C to 700°C.

6. The method for comprehensive utilization of all components of limonitic laterite nickel ore according to claim 1, characterized in that: In step 4, the reduction temperature is 500° C. to 600° C., and the reduction time is 15 min to 30 min.

7. The method for comprehensive utilization of all components of limonitic laterite nickel ore according to claim 1, characterized in that: In step 4, the flow rate of reducing gas is 0.10m 3 / kg~0.40m 3 / kg; The reducing gas is a mixed gas of H2, CO and N2, with a volume concentration of H2 of 15% to 25%, CO of 5% to 15% and the balance of N2.

8. The method for comprehensive utilization of all components of limonitic laterite nickel ore according to claim 7, characterized in that: The sum of the volume concentrations of H2 and CO is 20% to 40%.

9. The method for comprehensive utilization of all components of limonitic laterite nickel ore according to claim 1, characterized in that: In step 5, the ammonium salt is at least one of ammonium sulfate, ammonium carbonate, and ammonium bicarbonate; the liquid-to-solid ratio of the mixed solution to the reducing material is (2-4): 1 mL / g; The reaction time of atmospheric pressure ammonia leaching is 60min~120min; the stirring speed is 200r / min~600r / min; The pH value of the slurry is 9.5-11.

5.

10. The method for comprehensive utilization of all components of limonitic laterite nickel ore according to claim 1, characterized in that: In step 5, air is introduced after the atmospheric pressure ammonia leaching reaction for 30 minutes, and the air flow rate is controlled at 1.0 L / min-3.0 L / min.

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