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

Abstract

The invention relates to a method for extracting iron ore concentrate from laterite-nickel ore hydrometallurgical slag. The extraction method comprises the following steps: (1) heating biomass to 350-600 DEG C in a nitrogen atmosphere, carbonizing for 80-160 minutes, heating to 350-600 DEG C in a carbon dioxide atmosphere, activating for 40-70 minutes, grinding and sieving to obtain biomass charcoal; (2) mixing laterite-nickel ore hydrometallurgical slag, an additive and the biomass charcoal obtained in the step (1), and performing reduction roasting in an argon atmosphere to obtain a roasted product; and mixing and ball-milling the obtained roasted product and a dispersing agent, adding water for size mixing, and drying after magnetic separation to obtain iron ore concentrate. According to the method, the modified biomass charcoal is used as a reducing agent, roasting and magnetic separation operations are improved under the biomass charcoal condition, and efficient recovery of the iron ore concentrate is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of slag recycling, and in particular 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 plays an extremely important role in social economy. As the main material for the preparation of new energy batteries, the demand for nickel resources is also increasing with the rapid development of the new energy industry.

[0003] With the massive consumption of nickel sulfide ore resources, nickel sulfide ore resources are gradually becoming exhausted, and the international community has begun to invest in laterite nickel ore resources for nickel resource development. At present, the treatment of laterite nickel ore is mainly based on hydrometallurgical technology, which can have a good treatment effect on low-grade ores. However, laterite nickel ore will produce a large amount of metallurgical slag during the hydrometallurgical process, and the current treatment of metallurgical slag mainly adopts tailings dam accumulation, underground filter press backfill and deep sea landfill, which has problems such as high treatment cost, environmental pollution and waste of resources. The chemical composition of laterite nickel ore hydrometallurgical slag is complex, but its iron content exceeds 40%. Therefore, recycling 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 wet metallurgical slag. For example, CN116926312A discloses a method for preparing high-grade iron concentrate by microwave roasting of laterite nickel ore wet leaching slag, wherein the laterite nickel ore wet leaching slag and calcium-containing additives are uniformly mixed and then put into a microwave roasting furnace in the form of powder or pellets for microwave reduction roasting, and then the obtained microwave reduction roasting product is ground and magnetically separated to obtain a high-grade iron concentrate.

[0005] For the recycling of laterite nickel ore hydrometallurgical slag, coal, coke and natural gas are currently used as reducing agents, and the reducing agent is the key factor that determines the roasting effect and thus affects the iron recovery efficiency. For example, CN110616315A discloses a method for preparing nickel-iron concentrate from laterite nickel ore, comprising: drying and crushing the laterite nickel ore, mixing it with coal powder to make pellets; drying the pellets, mixing it with coal particles, and roasting it to obtain a reduction product; grinding the reduction product, and then subjecting it to at least one magnetic separation to obtain nickel-iron concentrate. Compared with non-renewable petrochemical resources such as coal and coke, biomass charcoal has the characteristics of wide distribution, low price and ecological environmental protection, so it is of great significance to use biomass charcoal to recover iron concentrate from laterite nickel ore hydrometallurgical slag. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, using biochar as a reducing agent and improving roasting and magnetic separation operations under biochar conditions, thereby achieving efficient recovery of iron concentrate.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, the extraction method comprising the following steps:

[0009] (1) heating the biomass to 350-600° C. in a nitrogen atmosphere, carbonizing the biomass for 80-160 min, then heating the biomass to 350-600° C. in a carbon dioxide atmosphere, activating the biomass for 40-70 min, and grinding and sieving the biomass charcoal;

[0010] (2) mixing the laterite nickel ore hydrometallurgical slag, additives and the biomass charcoal obtained in step (1) with an argon atmosphere and reducing roasting the mixture to obtain a roasted product; the obtained roasted product is mixed with a dispersant, ball-milled, and then water is added to prepare a slurry, and then magnetically separated and dried to obtain an iron ore concentrate.

[0011] The method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag provided by the present invention first optimizes the preparation process of biomass charcoal, and through the carbonization process under a nitrogen atmosphere, the biomass is subjected to high-temperature treatment, and its organic components are converted into inorganic carbon; then, through carbon dioxide activation treatment, its pore structure is regulated and improved, which is conducive to further improving the purity of iron concentrate. Compared with carbon sources such as coke and coal, the biomass charcoal provided by the present application has a comparable or even better iron concentrate recovery effect; combined with the use of additives, it can reduce the melting point and save energy consumption; in addition, adding a dispersant in the magnetic separation step can effectively ensure that the particulate matter is evenly dispersed in the liquid medium to prevent its precipitation and agglomeration.

[0012] Preferably, step (1) specifically includes:

[0013] (a) crushing the biomass, washing it with water and drying it at 90-100° C. for 400-520 min;

[0014] (b) in a nitrogen atmosphere, heating to 350-600° C. at a rate of 1-5° C. / min, carbonizing for 80-160 min, and naturally cooling to room temperature;

[0015] (c) in a carbon dioxide atmosphere, heating to 350-600° C. at a rate of 1-5° C. / min, activating for 40-70 min, and naturally cooling to room temperature;

[0016] (d) After grinding, the mixture is sieved through a 40-300 mesh sieve, washed with water, and dried at 110-120° C. for 680-800 min to obtain biochar.

[0017] The drying temperature in step (a) is 90-100° C., for example, 90° C., 92° C., 95° C., 98° C. or 100° C., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0018] The drying time in step (a) is 400-520 min, for example, 400 min, 450 min, 480 min, 500 min or 520 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0019] The heating rate in step (b) under a nitrogen atmosphere is 1-5°C / min, for example, 1°C / min, 2°C / min, 3°C / min, 4°C / min or 5°C / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] The temperature endpoint of the heating in the nitrogen atmosphere in step (b) is 350-600°C, for example, 350°C, 400°C, 450°C, 500°C, 550°C, 580°C or 600°C, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 500-600°C.

[0021] The carbonization treatment time in step (b) is 80-160 min, for example, 80 min, 100 min, 120 min, 150 min or 160 min, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 100-150 min.

[0022] When the temperature and time of the carbonization treatment are within the preferred range, a better iron recovery effect can be obtained.

[0023] The room temperature in step (b) is 15-35°C, for example, 15°C, 20°C, 25°C, 30°C or 35°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] The heating rate in step (c) under a carbon dioxide atmosphere is 1-5°C / min, for example, 1°C / min, 2°C / min, 3°C / min, 4°C / min or 5°C / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] The temperature endpoint of the heating in the carbon dioxide atmosphere in step (c) is 350-600°C, for example, 350°C, 450°C, 500°C, 550°C or 600°C, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 450-550°C.

[0026] The activation treatment time in step (c) is 40-70 min, for example, 40 min, 50 min, 55 min, 60 min or 70 min, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 50-60 min.

[0027] When the temperature and time of the activation treatment are within the preferred range, a better iron concentrate recovery effect can be obtained.

[0028] The room temperature in step (c) is 15-35°C, for example, 15°C, 20°C, 25°C, 30°C or 35°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] The mesh size of the sieving in step (d) is 40-300 mesh, for example, 40 mesh, 100 mesh, 200 mesh, 250 mesh or 300 mesh, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0030] The drying temperature in step (d) is 110-120°C, for example, 110°C, 112°C, 115°C, 118°C or 120°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0031] The drying time in step (d) is 680-800 min, for example, 680 min, 700 min, 720 min, 750 min or 800 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0032] Preferably, the biomass in step (1) comprises any one of coconut shells, wheat straws, corn straws, bamboo, rice straws, peanut shells or tree branches, or a combination of at least two of them. Typical but non-limiting combinations include a combination of coconut shells and wheat straws, a combination of corn straws, bamboo, rice straws and peanut shells, or a combination of coconut shells, wheat straws, corn straws, bamboo, rice straws, peanut shells and tree branches.

[0033] Preferably, the tree branches comprise fruit tree branches.

[0034] Preferably, the amount of biochar added in step (2) is 2-5wt% of the mass of laterite nickel ore hydrometallurgical slag, for example, it can be 2wt%, 3wt%, 3.5wt%, 4wt% or 5wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 3-4wt%.

[0035] Preferably, the amount of the additive added in step (2) is 4-6wt% of the mass of the laterite nickel ore hydrometallurgical slag, for example, it can be 4wt%, 4.5wt%, 5wt%, 5.5wt% or 6wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] Preferably, the additive in step (2) comprises Na2CO3 and / or NaOH, preferably a combination of Na2CO3 and NaOH.

[0037] Preferably, the mass ratio of Na2CO3 to NaOH is 1:(0.7-1.2), for example, it can be 1:0.7, 1:0.9, 1:1, 1:1.1 or 1:1.2, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] The present invention can reduce the melting point and save energy by adding Na2CO3 and / or NaOH as additives during the roasting process. At the same time, it is beneficial for some substances in the slag to react to generate sulfides, which are convenient for removal through the subsequent magnetic separation process, and finally further improve the purity of the iron ore concentrate.

[0039] Preferably, the mixing method in step (2) is ball milling for 30-120 min, for example, 30 min, 50 min, 70 min, 100 min or 120 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0040] Preferably, the reduction roasting in step (2) is: in an argon atmosphere, heating to 500-900° C. at a rate of 3-6° C. / min, and reduction roasting for 30-180 min.

[0041] The heating rate of the reduction roasting is 3-6°C / min, for example, 3°C / min, 4°C / min, 5°C / min or 6°C / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0042] The temperature end point of the reduction roasting is 500-900°C, for example, 500°C, 600°C, 700°C, 800°C or 900°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0043] The reduction roasting time is 30-180 min, for example, 30 min, 60 min, 100 min, 120 min or 180 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0044] Preferably, the introduction rate of argon gas is 1-5 mL / min, for example, 1 mL / min, 2 mL / min, 3 mL / min, 4 mL / min or 5 mL / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0045] Compared with nitrogen, using argon as an inert gas is more conducive to improving the purity of iron ore concentrate.

[0046] Preferably, the amount of the dispersant added in step (2) is 3-5wt% of the mass of the calcined product, for example, it can be 3wt%, 3.5wt%, 4wt%, 4.5wt% or 5wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] Preferably, the dispersant in step (2) includes any one of sodium metaphosphate, sodium hexametaphosphate, water glass, caustic starch or salinized water glass, or a combination of at least two of them. Typical but non-limiting combinations include a combination of sodium metaphosphate and sodium hexametaphosphate, a combination of water glass, caustic starch and salinized water glass, or a combination of sodium metaphosphate, sodium hexametaphosphate, water glass, caustic starch and salinized water glass.

[0048] The "salted water glass" refers to a mixture of water glass and aluminum sulfate.

[0049] Preferably, the amount of water used for slurrying in step (2) is 4-6 times the total mass of the calcined product and the dispersant, for example, it can be 4 times, 5 times or 6 times, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0050] Preferably, the intensity of the magnetic separation in step (2) is 1000-3000 Gs, for example, it can be 1000 Gs, 1500 Gs, 2000 Gs, 2500 Gs or 3000 Gs, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0051] As a preferred technical solution of the extraction method of the present invention, the extraction method comprises the following steps:

[0052] (1) The biomass is crushed, washed with water, and dried at 90-100°C for 400-520min; then, the temperature is increased to 350-600°C at a rate of 1-5°C / min in a nitrogen atmosphere, carbonized for 80-160min, and naturally cooled to room temperature; then, the temperature is increased to 350-600°C at a rate of 1-5°C / min in a carbon dioxide atmosphere, activated for 40-70min, and naturally cooled to room temperature; after grinding, the biomass is sieved through a 40-300 mesh sieve, washed with water, and dried at 110-120°C for 680-800min to obtain biochar;

[0053] (2) ball-milling the laterite nickel ore hydrometallurgical slag, the additive and the biomass carbon obtained in step (1) for 30-120 min, then heating to 500-900° C. at a rate of 3-6° C. / min under an argon atmosphere with a flow rate of 1-5 mL / min, and reduction roasting for 30-180 min to obtain a roasted product; the amount of the biomass carbon added is 2-5 wt% of the mass of the laterite nickel ore hydrometallurgical slag; the amount of the additive added is 4-6 wt% of the mass of the laterite nickel ore hydrometallurgical slag; the additive comprises Na2CO3 and / or NaOH, preferably a combination of Na2CO3 and NaOH, and the mass ratio of Na2CO3 to NaOH is 1:(0.7-1.2);

[0054] The obtained roasted product is mixed with a dispersant and ball-milled, and then water is added to prepare the slurry. After magnetic separation at an intensity of 1000-3000 Gs, the slurry is dried to obtain an iron concentrate. The amount of the dispersant added is 3-5wt% of the mass of the roasted product. The amount of water used for the slurry preparation is 4-6 times the total mass of the roasted product and the dispersant.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] (1) The method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag provided by the present invention first optimizes the preparation process of biomass charcoal, and through the carbonization process under a nitrogen atmosphere, the organic components of the biomass 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 purity of the iron concentrate. The calorific value of the prepared biomass charcoal is equivalent to that of commercial carbon sources, and has the advantages of stable performance, low sulfur content, and no heavy metals; more importantly, compared with carbon sources such as coke and coal, the biomass charcoal provided by the present application has a comparable or even better iron concentrate recovery effect.

[0057] (2) The present invention uses carbon dioxide as an activating agent, and the process flow is relatively simple. The waste gas generated is mainly carbon dioxide and water vapor, which has little pollution to the environment. In addition, the final biochar product has a high specific surface area, a developed pore structure, and a wide range of applications.

[0058] (3) The present invention can reduce the melting point and save energy by adding Na2CO3 and / or NaOH as additives during the roasting process. 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 ore concentrate. At the same time, compared with nitrogen, the use of argon as an inert gas is more conducive to improving the purity of the iron ore concentrate. In addition, adding a dispersant in the magnetic separation step can effectively ensure that the particulate matter is evenly dispersed in the liquid medium to prevent its precipitation and agglomeration.

[0059] (4) The present invention 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 long-term storage and landfill of laterite nickel ore hydrometallurgical slag.

[0060] (5) The extraction method provided by the present invention can better realize the recovery of iron concentrate from laterite nickel ore hydrometallurgical slag, and at the same time has the characteristics of being environmentally friendly, low cost, and high cost performance, and has good application prospects. DETAILED DESCRIPTION

[0061] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0062] In view of the resource utilization of laterite nickel ore hydrometallurgical slag, the present invention hopes to use biomass charcoal to replace existing reducing agents such as coal and coke, and explore a more environmentally friendly resource utilization method for laterite nickel ore hydrometallurgical slag. The present invention provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, and the extraction method comprises the following steps:

[0063] (1) The biomass is crushed, washed with water, and dried at 90-100°C for 400-520min; then, the temperature is increased to 350-600°C at a rate of 1-5°C / min in a nitrogen atmosphere, carbonized for 80-160min, and naturally cooled to room temperature; then, the temperature is increased to 350-600°C at a rate of 1-5°C / min in a carbon dioxide atmosphere, activated for 40-70min, and naturally cooled to room temperature; after grinding, the biomass is sieved through a 40-300 mesh sieve, washed with water, and dried at 110-120°C for 680-800min to obtain biochar;

[0064] (2) ball-milling the laterite nickel ore hydrometallurgical slag, the additive and the biomass carbon obtained in step (1) for 30-120 min, then heating to 500-900° C. at a rate of 3-6° C. / min under an argon atmosphere with a flow rate of 1-5 mL / min, and reduction roasting for 30-180 min to obtain a roasted product; the amount of the biomass carbon added is 2-5 wt% of the mass of the laterite nickel ore hydrometallurgical slag; the amount of the additive added is 4-6 wt% of the mass of the laterite nickel ore hydrometallurgical slag; the additive comprises Na2CO3 and / or NaOH, preferably a combination of Na2CO3 and NaOH, and the mass ratio of Na2CO3 to NaOH is 1:(0.7-1.2);

[0065] The obtained roasted product is mixed with a dispersant and ball-milled, and then water is added to prepare the slurry. After magnetic separation at an intensity of 1000-3000 Gs, the slurry is dried to obtain an iron concentrate. The amount of the dispersant added is 3-5wt% of the mass of the roasted product. The amount of water used for the slurry preparation is 4-6 times the total mass of the roasted product and the dispersant.

[0066] Based on the characteristics of laterite nickel ore hydrometallurgical slag, the present invention adopts biomass raw materials, and sequentially undergoes high-temperature treatment under a nitrogen atmosphere and a carbon dioxide atmosphere to obtain biomass charcoal that can effectively reduce iron in the laterite nickel ore hydrometallurgical slag. Based on the biomass charcoal, additives and their types, heating conditions, reduction roasting conditions such as a reaction atmosphere, and magnetic separation conditions such as a dispersant and magnetic separation intensity are improved, thereby achieving the purpose of replacing conventional reducing agents with biomass charcoal, and the recovery effect of the present invention has industrial value.

[0067] 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.

[0068] Table 1

[0069]

[0070] If no specific techniques or conditions are specified in the following examples, all of them are carried out according to the techniques or conditions described in the literature in the field or according to the product instructions; if the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be obtained commercially.

[0071] Example 1

[0072] This embodiment provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, the extraction method comprising the following steps:

[0073] (1) The coconut shell was crushed to less than 3 cm, washed with deionized water to remove surface impurities, and dried at 95°C for 480 min; then heated to 550°C at a rate of 3°C / min in a nitrogen atmosphere, carbonized for 120 min, and naturally cooled to room temperature; then heated to 500°C at a rate of 3°C / min in a carbon dioxide atmosphere, activated for 55 min, and naturally cooled to room temperature; after grinding, the coconut shell was sieved with a 200-mesh sieve, rinsed with deionized water three times to remove impurities, and then dried at 115°C for 720 min to obtain biochar;

[0074] (2) ball-milling the laterite nickel ore hydrometallurgical slag, Na2CO3, NaOH and the biomass carbon obtained in step (1) for 70 minutes, then heating to 700°C at a rate of 5°C / min under an argon atmosphere with a flow rate of 3 mL / min, and reduction roasting for 120 minutes to obtain a roasted product; the amount of the biomass carbon added is 3.5wt% of the mass of the laterite nickel ore hydrometallurgical slag; the total amount of Na2CO3 and NaOH added is 5wt% of the mass of the laterite nickel ore hydrometallurgical slag; the mass ratio of Na2CO3 to NaOH is 1:1;

[0075] The obtained roasted product is mixed with sodium metaphosphate and ball-milled for 30 minutes, and then water is added to prepare the slurry. After magnetic separation at an intensity of 2000 Gs, the mixture is dried to obtain an iron concentrate. The amount of sodium metaphosphate added is 4wt% of the mass of the roasted product. The amount of water used for the slurry preparation is 5 times the total mass of the roasted product and the sodium metaphosphate.

[0076] Example 2

[0077] This embodiment provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, the extraction method comprising the following steps:

[0078] (1) The corn stalks were crushed to less than 3 cm, washed with deionized water to remove surface impurities, and dried at 90°C for 520 min; then heated to 500°C at a rate of 1°C / min in a nitrogen atmosphere, carbonized for 150 min, and naturally cooled to room temperature; then heated to 450°C at a rate of 1°C / min in a carbon dioxide atmosphere, activated for 60 min, and naturally cooled to room temperature; after grinding, the stalks were sieved with 300 mesh, rinsed with deionized water three times to remove impurities, and then dried at 110°C for 800 min to obtain biochar;

[0079] (2) ball-milling the laterite nickel ore hydrometallurgical slag, Na2CO3, NaOH and the biomass carbon obtained in step (1) for 30 minutes, then heating to 500°C at a rate of 3°C / min under an argon atmosphere with a flow rate of 1 mL / min, and reduction roasting for 180 minutes to obtain a roasted product; the amount of the biomass carbon added is 3wt% of the mass of the laterite nickel ore hydrometallurgical slag; the total amount of Na2CO3 and NaOH added is 4wt% of the mass of the laterite nickel ore hydrometallurgical slag; the mass ratio of Na2CO3 to NaOH is 1:0.7;

[0080] The obtained roasted product is mixed with sodium hexametaphosphate and ball-milled, and then water is added to prepare the slurry. After magnetic separation at an intensity of 1000 Gs, the mixture is dried to obtain an iron concentrate. The amount of sodium hexametaphosphate added is 3wt% of the mass of the roasted product. The amount of water used for the slurry preparation is 4 times the total mass of the roasted product and the sodium hexametaphosphate.

[0081] Example 3

[0082] This embodiment provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, the extraction method comprising the following steps:

[0083] (1) The rice straw was crushed to less than 3 cm, washed with deionized water to remove surface impurities, and dried at 100°C for 400 min; then, the temperature was increased to 580°C at a rate of 5°C / min in a nitrogen atmosphere, carbonized for 100 min, and naturally cooled to room temperature; then, the temperature was increased to 550°C at a rate of 5°C / min in a carbon dioxide atmosphere, activated for 50 min, and naturally cooled to room temperature; after grinding, the rice straw was sieved with a 40-mesh sieve, rinsed with deionized water three times to remove impurities, and then dried at 120°C for 680 min to obtain biochar;

[0084] (2) ball-milling the laterite nickel ore hydrometallurgical slag, Na2CO3, NaOH and the biomass carbon obtained in step (1) for 120 min, then heating to 900°C at a rate of 6°C / min under an argon atmosphere with a flow rate of 5 mL / min, and reduction roasting for 30 min to obtain a roasted product; the amount of the biomass carbon added is 4 wt% of the mass of the laterite nickel ore hydrometallurgical slag; the total amount of Na2CO3 and NaOH added is 6 wt% of the mass of the laterite nickel ore hydrometallurgical slag; the mass ratio of Na2CO3 to NaOH is 1:1.2;

[0085] The obtained roasted product is mixed with water glass and ball-milled, and then water is added to prepare the slurry. After magnetic separation at an intensity of 3000 Gs, the mixture is dried to obtain an iron concentrate. The amount of water glass added is 5wt% of the mass of the roasted product. The amount of water used for the slurry preparation is 6 times the total mass of the roasted product and the water glass.

[0086] Example 4

[0087] This embodiment provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, which is different from Example 1 in that, except for adjusting the temperature of the carbonization treatment in step (1) to 350° C., the rest is the same as Example 1.

[0088] Example 5

[0089] This embodiment provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, which is different from Example 1 in that, except for adjusting the temperature of the carbonization treatment in step (1) to 600° C., the rest is the same as Example 1.

[0090] Example 6

[0091] This embodiment provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, which is different from Example 1 in that, except for adjusting the temperature of the activation treatment in step (1) to 350° C., the rest is the same as Example 1.

[0092] Example 7

[0093] This embodiment provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, which is different from Example 1 in that, except for adjusting the temperature of the activation treatment in step (1) to 600° C., the rest is the same as Example 1.

[0094] Example 8

[0095] This embodiment provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, which is different from Example 1 in that, except for adjusting the amount of biomass charcoal added in step (2) to 2wt% of the mass of the laterite nickel ore hydrometallurgical slag, the rest is the same as Example 1.

[0096] Example 9

[0097] This embodiment provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, which is different from Example 1 in that, except for adjusting the amount of biomass charcoal added in step (2) to 5wt% of the mass of the laterite nickel ore hydrometallurgical slag, the rest is the same as Example 1.

[0098] Example 10

[0099] This embodiment provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, which is different from Example 1 in that, except for replacing the Na2CO3 and NaOH in step (2) with a single Na2CO3, the rest is the same as Example 1.

[0100] Embodiment 11

[0101] This embodiment provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, which is different from Example 1 in that, except for replacing the equal mass of Na2CO3 and NaOH in step (2) with a single NaOH, the rest is the same as Example 1.

[0102] Comparative Example 1

[0103] This comparative example provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, which differs from Example 1 in that step (1) is omitted, and the mass of biomass charcoal in step (2) is replaced by coke, and the rest is the same as Example 1.

[0104] Comparative Example 2

[0105] This comparative example provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, which is different from Example 1 in that there is no activation treatment step in step (1), and the rest is the same as Example 1.

[0106] Comparative Example 3

[0107] This comparative example provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, which differs from Example 1 in that no additive is added in step (2), and the rest is the same as Example 1.

[0108] Comparative Example 4

[0109] This comparative example provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, which differs from Example 1 in that the reduction roasting in step (2) is carried out under a nitrogen atmosphere, and the rest is the same as Example 1.

[0110] Comparative Example 5

[0111] This comparative example provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, which is different from Example 1 in that, except for adjusting the temperature of the carbonization treatment in step (1) to 300° C., the rest is the same as Example 1.

[0112] Comparative Example 6

[0113] This comparative example provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, which is different from Example 1 in that, except for adjusting the temperature of the carbonization treatment in step (1) to 650° C., the rest is the same as Example 1.

[0114] Comparative Example 7

[0115] This comparative example provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, which is different from Example 1 in that, except for adjusting the temperature of the activation treatment in step (1) to 300° C., the rest is the same as Example 1.

[0116] Comparative Example 8

[0117] This comparative example provides a method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, which is different from Example 1 in that, except for adjusting the temperature of the activation treatment in step (1) to 650° C., the rest is the same as Example 1.

[0118] The yield of the iron concentrate obtained in Examples 1-11 and Comparative Examples 1-8 was calculated by (the mass of the target substance after magnetic separation / the initial mass of the laterite nickel ore metallurgical slag)*100%, and the purity was calculated by (the mass of the target substance after magnetic separation / the mass of the substance after magnetic separation)*100%. The results are shown in Table 2.

[0119] Table 2

[0120]

[0121]

[0122] It can be seen from Table 2 that the extraction method provided by the present invention can better realize the recovery of iron concentrate from laterite nickel ore hydrometallurgical slag, and the method is environmentally friendly, low cost, high cost performance, etc., and has good application prospects.

[0123] By comparing Example 1 with Examples 4-7 and Comparative Examples 5-8, it can be seen that when the temperature of the carbonization treatment or activation treatment is within the preferred range, a higher iron concentrate purity can be obtained, and when the temperature exceeds the limited range, the iron concentrate purity will be significantly reduced; by comparing Example 1 with Examples 8 and 9, it can be seen that when the amount of biochar added is within the preferred range, a higher iron concentrate purity can be obtained; by comparing Example 1 with Examples 10 and 11, it can be seen that the use of a compound additive, compared with a single additive, the iron concentrate purity obtained after reduction roasting and magnetic separation is higher.

[0124] By comparing Example 1 with Comparative Example 1, it can be seen that when coke is used as a reducing agent, the purity of the iron concentrate is significantly reduced; by comparing Example 1 with Comparative Example 2, it can be seen that there is no activation treatment step in the preparation of biochar, and its pore structure cannot be optimized, thereby reducing the purity of the iron concentrate; by comparing Example 1 with Comparative Example 3, it can be seen that without adding additives, the purity of the iron concentrate cannot be further improved; by comparing Example 1 with Comparative Example 4, it can be seen that the reduction roasting is carried out under a nitrogen atmosphere, and the purity of the obtained iron concentrate is reduced compared to that in an argon atmosphere.

[0125] In summary, the method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag provided by the present invention first optimizes the preparation process of biomass charcoal, and through the carbonization process under a nitrogen atmosphere, the biomass is subjected to high-temperature treatment, and its organic components are converted into inorganic carbon; then, through carbon dioxide activation treatment, its pore structure is regulated and improved, which is conducive to further improving the purity of iron concentrate. The calorific value of the prepared biomass charcoal is equivalent to that of commercial carbon sources, and has the advantages of stable performance, low sulfur content, and no heavy metals; more importantly, compared with carbon sources such as coke and coal, the biomass charcoal provided by this application has a comparable or even better iron concentrate recovery effect.

[0126] The present invention uses carbon dioxide as an activating agent, has a relatively simple process flow, generates waste gas mainly composed of carbon dioxide and water vapor, 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.

[0127] The present invention can reduce the melting point and save energy by adding Na2CO3 and / or NaOH as additives during the roasting process. At the same time, it is beneficial for some substances in the slag to react to generate sulfides, which are convenient for removal through the subsequent magnetic separation process, and finally further improve the purity of the iron ore concentrate. At the same time, compared with nitrogen, the use of argon as an inert gas is more conducive to improving the purity of the iron ore concentrate. In addition, adding a dispersant in the magnetic separation step can effectively ensure that the particulate matter is evenly dispersed in the liquid medium to prevent its precipitation and agglomeration.

[0128] The present invention 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 long-term storage and landfill of laterite nickel ore hydrometallurgical slag.

[0129] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for extracting iron concentrate from laterite nickel ore hydrometallurgical slag, characterized in that: The extraction method comprises the following steps: (1) heating the biomass to 350-600° C. in a nitrogen atmosphere, carbonizing the biomass for 80-160 min, then heating the biomass to 350-600° C. in a carbon dioxide atmosphere, activating the biomass for 40-70 min, and grinding and sieving the biomass charcoal; (2) mixing the laterite nickel ore hydrometallurgical slag, additives and the biomass charcoal obtained in step (1) with an argon atmosphere and reducing roasting the mixture to obtain a roasted product; the obtained roasted product is mixed with a dispersant, ball-milled, and then water is added to prepare a slurry, and then magnetically separated and dried to obtain an iron ore concentrate.

2. The extraction method according to claim 1, characterized in that Step (1) specifically includes: (a) crushing the biomass, washing it with water and drying it at 90-100° C. for 400-520 min; (b) in a nitrogen atmosphere, heating to 350-600° C. at a rate of 1-5° C. / min, carbonizing for 80-160 min, and naturally cooling to room temperature; (c) in a carbon dioxide atmosphere, heating to 350-600° C. at a rate of 1-5° C. / min, activating for 40-70 min, and naturally cooling to room temperature; (d) After grinding, the mixture is sieved through a 40-300 mesh sieve, washed with water, and dried at 110-120° C. for 680-800 min to obtain biochar.

3. The extraction method according to claim 1 or 2, characterized in that The temperature end point of the heating in the nitrogen atmosphere in step (1) is 500-600° C., and the carbonization treatment is performed for 100-150 minutes.

4. The extraction method according to any one of claims 1 to 3, characterized in that The end point of the heating in the carbon dioxide atmosphere in step (1) is 450-550° C., and the activation treatment is performed for 50-60 minutes.

5. The extraction method according to any one of claims 1 to 4, characterized in that The biomass in step (1) comprises any one of coconut shells, wheat straw, corn straw, bamboo, rice straw, peanut shells or tree branches, or a combination of at least two thereof; Preferably, the amount of biomass charcoal added in step (2) is 2-5wt% of the mass of the laterite nickel ore hydrometallurgical slag, preferably 3-4wt%.

6. The extraction method according to any one of claims 1 to 5, characterized in that The amount of the additive added in step (2) is 4-6wt% of the mass of the laterite nickel ore hydrometallurgical slag; Preferably, the additive in step (2) comprises Na2CO3 and / or NaOH, preferably a combination of Na2CO3 and NaOH; Preferably, the mass ratio of Na2CO3 to NaOH is 1:(0.7-1.2).

7. The extraction method according to any one of claims 1 to 6, characterized in that The mixing method in step (2) is ball milling for 30-120 minutes; Preferably, the reduction roasting in step (2) is: heating to 500-900° C. at a rate of 3-6° C. / min under an argon atmosphere, and reduction roasting for 30-180 min; Preferably, the introduction rate of argon gas is 1-5 mL / min.

8. The extraction method according to any one of claims 1 to 7, characterized in that The amount of the dispersant added in step (2) is 3-5wt% of the mass of the calcined product; Preferably, the dispersant in step (2) comprises any one of sodium metaphosphate, sodium hexametaphosphate, water glass, caustic starch or salinized water glass, or a combination of at least two thereof.

9. The extraction method according to any one of claims 1 to 8, characterized in that The amount of water used in the step (2) for slurry preparation is 4-6 times the total mass of the roasted product and the dispersant; Preferably, the intensity of the magnetic separation in step (2) is 1000-3000 Gs.

10. The extraction method according to claim 1, characterized in that The extraction method comprises the following steps: (1) The biomass is crushed, washed with water, and dried at 90-100°C for 400-520min; then, the temperature is increased to 350-600°C at a rate of 1-5°C / min in a nitrogen atmosphere, carbonized for 80-160min, and naturally cooled to room temperature; then, the temperature is increased to 350-600°C at a rate of 1-5°C / min in a carbon dioxide atmosphere, activated for 40-70min, and naturally cooled to room temperature; after grinding, the biomass is sieved through a 40-300 mesh sieve, washed with water, and dried at 110-120°C for 680-800min to obtain biochar; (2) ball-milling the laterite nickel ore hydrometallurgical slag, the additive and the biomass carbon obtained in step (1) for 30-120 min, then heating to 500-900° C. at a rate of 3-6° C. / min under an argon atmosphere with a flow rate of 1-5 mL / min, and reduction roasting for 30-180 min to obtain a roasted product; the amount of the biomass carbon added is 2-5 wt% of the mass of the laterite nickel ore hydrometallurgical slag; the amount of the additive added is 4-6 wt% of the mass of the laterite nickel ore hydrometallurgical slag; the additive comprises Na2CO3 and / or NaOH, preferably a combination of Na2CO3 and NaOH, and the mass ratio of Na2CO3 to NaOH is 1:(0.7-1.2); The obtained roasted product is mixed with a dispersant and ball-milled, and then water is added to prepare the slurry. After magnetic separation at an intensity of 1000-3000 Gs, the slurry is dried to obtain an iron concentrate. The amount of the dispersant added is 3-5wt% of the mass of the roasted product. The amount of water used for the slurry preparation is 4-6 times the total mass of the roasted product and the dispersant.

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