Method for extracting iron ore concentrate from laterite-nickel ore hydrometallurgical slag

Abstract

The invention belongs to the technical field of slag recycling, and discloses a method for extracting iron ore concentrate from laterite-nickel ore hydrometallurgical slag, which comprises the following steps: heating biomass to 350-600 DEG C in a nitrogen atmosphere for treatment, heating to 350-600 DEG C in a carbon dioxide atmosphere for treatment, cooling, crushing and sieving to obtain biomass charcoal; the laterite-nickel ore hydrometallurgical slag, biomass charcoal and an additive are mixed and then subjected to reduction roasting, and a roasted product is obtained; and adding a dispersing agent into the roasted product, carrying out ball milling, and carrying out size mixing and magnetic separation to obtain iron ore concentrate. The process for extracting the iron ore concentrate from the biomass charcoal is developed for the laterite-nickel ore hydrometallurgical slag, has the advantages of being short in process, low in cost, environmentally friendly, good in recovery effect and the like, and has a positive effect on solving the environmental problems caused by long-term stockpiling, landfill and the like of the laterite-nickel ore hydrometallurgical slag.

Description

Technical Field

[0001] The present application belongs to the technical field of slag recycling and utilization, and specifically relates to a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag. Background Art

[0002] Nickel is a strategic reserve metal with a wide range of applications and a crucial role in society and the economy. As a primary material for new energy battery production, the demand for nickel resources is increasing with the rapid development of the new energy industry.

[0003] With the massive consumption of nickel sulfide ore resources, these resources are gradually becoming depleted, and the international community has begun to focus its nickel resource development efforts on laterite nickel ore resources. Currently, the treatment of laterite nickel ore mainly relies on hydrometallurgical processes, which can achieve good treatment results for low-grade ores. However, laterite nickel ore produces a large amount of metallurgical slag during the hydrometallurgical process. Currently, the treatment of metallurgical slag mainly involves tailings dam accumulation, underground filter press backfill, and deep-sea landfill, which pose problems such as high treatment costs, environmental pollution, and waste of resources. The chemical composition of laterite nickel ore hydrometallurgical slag is complex, but its iron content exceeds 40%. Therefore, recovering and reusing iron resources from laterite nickel ore hydrometallurgical slag is an effective solution.

[0004] At present, the reduction roasting-magnetic separation process is mainly used to recover iron concentrate from laterite nickel ore hydrometallurgical slag. Specifically, a reducing agent is added to the metallurgical slag and roasted under high temperature, and then the iron concentrate is separated by magnetic separation. For the recycling of laterite nickel ore hydrometallurgical slag, coal, coke, and natural gas are currently used as reducing agents; however, according to the principle of reduction roasting, other carbon substances can also be used as reducing agents. Compared with non-renewable petrochemical resources such as coal and coke, biomass carbon has the characteristics of wide distribution, low price and environmental protection. Therefore, it is of great significance to use biomass carbon to recover iron concentrate from laterite nickel ore hydrometallurgical slag. However, existing studies have shown that the reducing agent is the key factor that determines the roasting effect and thus affects the iron recovery efficiency. In addition, the inventor's previous research has shown that the preparation conditions of biomass carbon are crucial to the iron recovery efficiency. Summary of the Invention

[0005] In view of this, the present application aims to provide a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, which uses biochar as a reducing agent and improves roasting and magnetic separation operations under biochar conditions to achieve efficient recovery of iron.

[0006] The technical solutions of this application are as follows: A method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag comprises the following steps: S1. The biomass is first heated to 350-600°C in a nitrogen atmosphere for 80-160 min, cooled naturally, and then heated to 350-600°C in a carbon dioxide atmosphere for 40-70 min, cooled naturally, and ground and sieved to obtain biochar; S2, reducing and roasting the mixture of laterite nickel ore hydrometallurgical slag, biochar and additives to obtain a roasted product; S3. Add a dispersant to the roasted product, add water after ball milling to obtain an intermediate slurry, and dry it after magnetic separation to obtain iron concentrate.

[0007] Preferably, in the above method, step S1 includes the following process: S11, preliminarily crushing the biomass, washing with water to remove impurities, and drying at 90-100° C. for 400-520 min, wherein the biomass is one or more of coconut shells, wheat straw, corn stalks, bamboo, rice straw, peanut shells, and tree branches (such as various fruit tree branches); S12. Under nitrogen atmosphere, heat to 350-600°C at a heating rate of 1-5°C / min for 80-160 min, and cool naturally to room temperature (15-35°C); S13, in a carbon dioxide atmosphere, heating to 350-600°C at a heating rate of 1-5°C / min for activation treatment for 40-70 min, and then naturally cooling to room temperature; S14, after grinding, passing through a 40-300 mesh sieve, washing with water to remove impurities, and then drying at 110-120° C. for 680-800 minutes to obtain biochar.

[0008] Preferably, in the above method, the amount of biochar added is 2-5 wt% of the mass of the laterite nickel ore hydrometallurgical slag.

[0009] Preferably, in the above method, the additive is Na2CO3 and / or NaOH; more preferably, the amount of the additive added is 4-6 wt% of the mass of the laterite nickel ore hydrometallurgical slag.

[0010] Preferably, in the above method, step S2 is performed by ball milling to mix the materials; more preferably, the ball milling time is 30-120 min.

[0011] Preferably, in the above method, the reduction calcination is carried out in an argon atmosphere at a temperature of 3-6°C / min up to 500-900°C for 30-180 min.

[0012] More preferably, the argon gas introduction rate is 1-5 mL / min.

[0013] Preferably, in the above method, the dispersant used in step S2 is one or more of sodium metaphosphate, sodium hexametaphosphate, water glass, caustic starch, and salinized water glass (i.e., a mixture of water glass and aluminum sulfate), and the amount of the dispersant added is 3-5 wt% of the mass of the roasted product.

[0014] Preferably, in the above method, in step S3, water in an amount of 4-6 times the mass of the solid material is added for slurry adjustment, thereby obtaining an intermediate slurry.

[0015] Preferably, in the above method, the intensity of magnetic separation is 1000-3000 Gs.

[0016] Compared with the prior art, the present invention has the following advantages: The chemical composition of laterite nickel ore hydrometallurgical slag is relatively complex, containing multiple mineral types and a high content of the harmful impurity S. This application optimizes the biochar preparation process for the extraction of iron concentrate from laterite nickel ore hydrometallurgical slag. The resulting biochar has a calorific value comparable to that of commercial carbon sources and offers advantages such as stable performance, low sulfur content, and the absence of heavy metals. More importantly, compared to other carbon sources (such as coke and coal), the biochar provided in this application has comparable or even superior iron recovery performance.

[0017] In the preparation process of the biochar of the present application, the biomass is subjected to a carbonization process under a nitrogen atmosphere, and its organic components are converted into inorganic carbon after high-temperature treatment; then the pore structure is regulated and improved through carbon dioxide activation treatment, which is conducive to further improving the iron recovery effect; the present application uses carbon dioxide as an activating agent, the process flow is relatively simple, and the waste gas generated is mainly CO2 and water vapor, which has little pollution to the environment, and the final biochar product has a high specific surface area, a developed pore structure, and a wide range of applications.

[0018] The present application adds Na2CO3 and / or NaOH as additives during the roasting process, which can reduce the melting point and save energy consumption. At the same time, it is beneficial for some substances in the slag to react to form sulfides, which are convenient for removal through the subsequent magnetic separation process, and ultimately further improve the purity of the iron concentrate. At the same time, the inventor found during the experiment that compared with nitrogen, the use of argon as an inert gas is more conducive to improving the purity of the iron concentrate.

[0019] Based on the biochar used as a reducing agent in this application, this application provides a certain carbon source and reduces the roasting temperature during the roasting process by mixing a certain amount of Na2CO3 and / or NaOH as additives. In combination with an argon atmosphere, it can effectively ensure the iron recovery effect. In addition, the addition of a dispersant during the magnetic separation step can effectively ensure the uniform dispersion of particulate matter in the liquid medium, preventing its precipitation and agglomeration.

[0020] This application is the first to use biochar in the reduction roasting of laterite nickel ore hydrometallurgical slag to recover iron. The recovery effect is comparable to or even better than that of coal or other reducing agents prepared with coal as raw materials (such as coke). In addition, biochar is more environmentally friendly, has lower cost and higher cost-effectiveness.

[0021] The method of the present application can recover iron concentrate products from laterite nickel ore hydrometallurgical slag, and the obtained non-magnetic material can be used to produce building materials or cement products, thereby improving the resource utilization rate and economic benefits of laterite nickel ore, and playing a positive role in solving the environmental problems caused by the long-term storage and landfill of laterite nickel ore hydrometallurgical slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a process flow chart of the method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag provided in this application. DETAILED DESCRIPTION

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The term "comprise" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusions.

[0024] In view of the resource utilization of laterite nickel ore hydrometallurgical slag, this application hopes to use biomass charcoal to replace existing reducing agents such as coal and coke, and explore a more environmentally friendly way to recycle laterite nickel ore hydrometallurgical slag. Figure 1 As shown, the present application provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, comprising the following steps: (1) Preparation of biochar: The biomass is first heated to 350-600°C in a nitrogen atmosphere for 80-160 min, cooled naturally, then heated to 350-600°C in a carbon dioxide atmosphere for 40-70 min, cooled naturally, and ground and sieved to obtain biochar; (2) Reduction roasting: mixing laterite nickel ore hydrometallurgical slag, biochar and additives, and then reducing roasting under a certain atmosphere to obtain a roasted product; (3) Magnetic separation: After adding a dispersant to the roasted product and ball milling, water is added to prepare an intermediate slurry. The intermediate slurry is magnetically separated at a specific magnetic separation intensity, and the magnetic and non-magnetic substances are obtained after filtering and drying.

[0025] Based on the characteristics of laterite nickel ore hydrometallurgical slag, this application uses biomass raw materials and sequentially undergoes high-temperature treatment under nitrogen atmosphere and carbon dioxide atmosphere to obtain biomass carbon that can effectively reduce iron in laterite nickel ore hydrometallurgical slag. Based on the biomass carbon, the reduction roasting conditions (such as additives and their types, heating conditions, reaction atmosphere, etc.) and magnetic separation conditions (such as dispersants and magnetic separation intensity) are improved, thereby achieving the purpose of replacing conventional reducing agents with biomass carbon, and the recovery effect of this scheme has industrial value.

[0026] The technical solution of the present application will be described clearly and completely below in conjunction with specific embodiments. It should be understood that the embodiments described herein are only used to illustrate and explain the present application and are not intended to limit the present application.

[0027] The composition of the laterite nickel ore hydrometallurgical slag (using sulfuric acid as the leaching medium) used in the following examples and comparative examples is shown in Table 1.

[0028] Table 1 Analysis of main components of laterite nickel ore hydrometallurgical slag

[0029] If no specific techniques or conditions are specified in the following examples, the procedures were carried out in accordance with the techniques or conditions described in the literature in the field or in accordance with the product instructions; if no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0030] Example 1 A method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag comprises the following steps: (1) Preparation of biochar.

[0031] Biochar is prepared from coconut shells as biomass raw materials through the following process: ① Crushed the coconut shell to less than 3 cm, removed surface impurities with deionized water, and then dried at 100°C for 480 min; ② Under nitrogen atmosphere, heat to 500℃ at a heating rate of 5℃ / min and anneal for 120 min, then cool naturally to room temperature; ③ In a carbon dioxide atmosphere, heat the sample to 450°C at a heating rate of 5°C / min for 60 min, and then cool the sample naturally to room temperature. ④ Grind with a ball mill, pass through a 200-mesh sieve, rinse with deionized water three times to remove impurities, and then dry at 120°C for 720 min to obtain biochar.

[0032] (2) Reduction roasting.

[0033] Laterite nickel ore hydrometallurgical slag, 3 wt% biochar and 5 wt% Na2CO3 were uniformly ball milled in a ball mill for 70 min. The milled material was placed in an atmosphere furnace and heated to 700℃ at an argon flow rate of 3 mL / min and a heating rate of 5℃ / min for 120 min for reduction roasting to obtain a roasted product.

[0034] (3) Magnetic separation.

[0035] 4 wt% sodium metaphosphate was added to the roasted product and ball milled for 30 min. Then, slurry was adjusted and the amount of water added was 5 times the mass of the solid material to obtain an intermediate slurry. The intermediate slurry was magnetically separated at a magnetic separation intensity of 2000 Gs, and magnetic and non-magnetic substances were obtained after filtration and drying. The magnetic substance was the iron concentrate product.

[0036] Example 2 Different from Example 1, the biochar in this example uses corn stalks as raw material, and the preparation process is as follows: ① Crush the corn stalks to less than 3 cm, remove surface impurities with deionized water, and then dry them at 90°C for 500 min; ② Under nitrogen atmosphere, heat to 400℃ at a heating rate of 3℃ / min for 120 min, and then cool naturally to room temperature; ③ In a carbon dioxide atmosphere, heat the sample to 550°C at a heating rate of 3°C / min for 60 min, and then cool the sample naturally to room temperature. ④ Grind with a ball mill, pass through a 300-mesh sieve, rinse with deionized water three times to remove impurities, and then dry at 120°C for 720 min to obtain biochar.

[0037] Example 3 Different from Example 1, step (2) in this example is specifically as follows: Laterite nickel ore hydrometallurgical slag, 4 wt% biochar and 5 wt% additives (Na2CO3 to NaOH mass ratio of 1:1) were uniformly ball milled in a ball mill for 100 min. The milled material was placed in an atmosphere furnace and heated to 600℃ with an argon flow rate of 3 mL / min and a heating rate of 3℃ / min for 180 min for reduction roasting to obtain the roasted product.

[0038] Comparative Example 1 Different from Example 1, this example uses coke as a reducing agent and includes the following steps: (1) Reduction roasting.

[0039] Laterite nickel ore hydrometallurgical slag, 3 wt% coke and 5 wt% Na2CO3 were uniformly ball milled in a ball mill for 70 min. The milled material was placed in an atmosphere furnace, heated to 700℃ at an argon flow rate of 3 mL / min and a heating rate of 5℃ / min, and then reduction roasted for 120 min to obtain a calcined product.

[0040] (2) Magnetic separation.

[0041] 4 wt% sodium metaphosphate was added to the roasted product and ball milled for 30 min. Then, slurry was adjusted and the amount of water added was 5 times the mass of the solid material to obtain an intermediate slurry. The intermediate slurry was magnetically separated at a magnetic separation intensity of 2000 Gs, and magnetic and non-magnetic substances were obtained after filtration and drying. The magnetic substance was the iron concentrate product.

[0042] Comparative Example 2 Different from Example 1, the preparation process of biochar in this example is as follows: ① Crushed the coconut shell to less than 3 cm, removed surface impurities with deionized water, and then dried at 100°C for 480 min; ② Under nitrogen atmosphere, heat to 500℃ at a heating rate of 5℃ / min and anneal for 120 min, then cool naturally to room temperature; ③ Grind with a ball mill, pass through a 200-mesh sieve, rinse with deionized water three times to remove impurities, and then dry at 120°C for 720 min to obtain biochar.

[0043] Comparative Example 3 Different from Example 1, step (2) in this example does not contain additives, and specifically comprises: Laterite nickel ore hydrometallurgical slag and 3 wt% biochar were uniformly ball-milled in a ball mill for 70 min. The milled material was placed in an atmosphere furnace and heated to 700°C at an argon flow rate of 3 mL / min and a heating rate of 5°C / min for 120 min for reduction roasting to obtain a roasted product.

[0044] Comparative Example 4 Different from Example 1, step (2) in this example is specifically as follows: Laterite nickel ore hydrometallurgical slag, 3 wt% biochar and 5 wt% Na2CO3 were uniformly ball milled in a ball mill for 70 min. The milled material was placed in an atmosphere furnace and heated to 700°C for 120 min at a nitrogen flow rate of 3 mL / min and a heating rate of 5°C / min to obtain a calcined product.

[0045] The iron ore concentrates obtained in each embodiment and comparative example were analyzed, and their yields and purities were calculated, as shown in Table 2.

[0046] Table 2 Recovery effects under different treatment methods

[0047] From the above results, it can be seen that the biochar prepared by the special method of the present application combined with the iron concentrate extraction method of the present application can better realize the recovery of iron concentrate from laterite nickel ore hydrometallurgical slag, and this method has the characteristics of environmental friendliness, low cost, and high cost performance, and has good application prospects.

[0048] It should be noted that the above embodiments are only part of the embodiments of this application rather than all the embodiments, and are only used to illustrate the technical solutions of this application rather than to limit them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

Claims

1. A method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, characterized in that: The following steps are involved: S1. The biomass is first heated to 350-600°C in a nitrogen atmosphere for 80-160 min, cooled naturally, and then heated to 350-600°C in a carbon dioxide atmosphere for 40-70 min, cooled naturally, and ground and sieved to obtain biochar; S2, reducing and roasting the mixture of laterite nickel ore hydrometallurgical slag, biochar and additives to obtain a roasted product; S3. Add a dispersant to the roasted product, add water to prepare the slurry after ball milling, separate by magnetic separation and dry to obtain the iron ore concentrate.

2. The method according to claim 1, characterized in that Step S1 is specifically as follows: S11, preliminarily crushing the biomass, washing with water to remove impurities, and then drying at 90-100°C for 400-520 min; S12, under nitrogen atmosphere, heating to 350-600°C at 1-5°C / min for 80-160 min, and then naturally cooling to room temperature; S13, in a carbon dioxide atmosphere, heating to 350-600°C at 1-5°C / min for activation treatment for 40-70 min, and then naturally cooling to room temperature; S14, after grinding, passing through a 40-300 mesh sieve, washing with water to remove impurities, and then drying at 110-120° C. for 680-800 min to obtain biochar.

3. The method according to claim 2, characterized in that The biomass is one or more of coconut shells, wheat straw, corn straw, bamboo, rice straw, peanut shells and tree branches.

4. The method according to claim 1, wherein The amount of the biomass charcoal added is 2-5 wt% of the mass of the laterite nickel ore hydrometallurgical slag.

5. The method according to claim 1, wherein The additive is Na2CO3 and / or NaOH.

6. The method according to claim 5, wherein The amount of the additive added is 4-6 wt% of the mass of the laterite nickel ore hydrometallurgical slag.

7. The method according to claim 1, characterized in that The mixing method in step S2 is ball milling.

8. The method according to claim 1, wherein The reduction roasting in step S2 is as follows: in an argon atmosphere, the temperature is raised to 500-900° C. at a rate of 3-6° C. / min and the reduction roasting is performed for 30-180 min.

9. The method according to claim 1, wherein The dispersant is one or more of sodium metaphosphate, sodium hexametaphosphate, water glass, caustic starch, and salinized water glass, and the amount of the dispersant added is 3-5 wt% of the mass of the roasted product.

10. The method according to claim 1, wherein The intensity of the magnetic separation is 1000-3000 Gs.

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