Method for recovering laterite-nickel ore leaching residues

Abstract

The recovery method of the laterite-nickel ore leaching residues comprises the following steps that S1, in the presence of a first reducing agent, the laterite-nickel ore leaching residues are roasted, and roasted sand and sulfur-containing tail gas are obtained; s2, in the presence of a second reducing agent, smelting the roasted product obtained in the step S1 to obtain molten iron, smelting slag and coal gas; the laterite-nickel ore leaching residues are in a dry state; the smelting slag is a MgO-Al2O3-SiO2-FeO slag system, and the smelting slag is a MgO-Al2O3-SiO2 The ratio of the total mass of fixed carbon in the first reducing agent to the total mass of sulfur in the laterite-nickel ore leaching residues is 0.35-0.50. According to the recycling method, iron and sulfur in the laterite-nickel ore leaching residues can be comprehensively recycled under the condition that extra flux is not needed, resource utilization of the laterite-nickel ore high-pressure leaching residues is achieved under the condition that the overall process cost is low, and large-scale industrial use is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgical waste recycling, and in particular relates to a method for recycling laterite nickel ore leaching slag. Background Art

[0002] With the rapid development of the new energy industry and the increasing scarcity of nickel sulfide ore resources, laterite nickel ore has become the main source of nickel supply. Hydrometallurgy is a common process for processing laterite nickel ore. Specifically, it uses high-pressure acid leaching to extract valuable metals such as nickel and cobalt from laterite nickel ore. The commonly used acid leaching now uses sulfuric acid, which will produce a large amount of laterite nickel ore leaching slag that is difficult to handle; and the laterite nickel ore hydrochloric acid and nitric acid high-pressure acid leaching process, which is more convenient for leaching slag treatment, is still in the experimental stage. At present, the obtained laterite nickel ore leaching slag is usually directly stored, but this will cause a serious threat to the ecological environment of the storage site, and will also increase the environmental protection pressure and operating costs of enterprises. Iron in laterite nickel ore leaching slag is a macro element, with an iron content of up to 60%, which is a potential source of iron resources in the iron and steelmaking industry. However, in the laterite nickel ore leaching slag, the mineral particle size is extremely fine, the minerals are intermixed and coexist, the sulfur content is high, and the magnetic difference of the minerals is small. The iron recovery rate of the iron concentrate selected by the conventional beneficiation process is low and the impurity content of the concentrate is high. In the prior art, there are two process routes for processing laterite nickel ore leaching slag to recover iron. One is centered on magnetic separation, and the final product is iron concentrate, but the iron concentrate selected by this process has low iron concentrate grade, high sulfur content, and low overall iron recovery rate. The other is centered on smelting, and the final product is molten iron, but in this process, flux needs to be added to adjust the slag shape and melting point, which is costly, requires large slag volume, and consumes high energy. Summary of the invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the defects of low recovery rate, high impurity content, high cost, high energy consumption, etc. when processing laterite nickel ore leaching residue to recover iron in the prior art, thereby providing a method for recovering laterite nickel ore leaching residue.

[0004] To this end, the present invention provides the following technical solutions.

[0005] The invention provides a method for recovering laterite nickel ore leaching slag, comprising the following steps: S1: roasting the laterite nickel ore leaching slag in the presence of a first reducing agent to obtain roasted sand and sulfur-containing tail gas; S2: smelting the roasted sand obtained in S1 in the presence of a second reducing agent to obtain molten iron, smelting slag and coal gas; the laterite nickel ore leaching slag is in a dry state; the smelting slag is a MgO-Al2O3-SiO2-FeO slag system; the ratio of the total mass of fixed carbon in the first reducing agent to the total mass of sulfur in the laterite nickel ore leaching slag is 0.35-0.50.

[0006] Optionally, in step S1, before roasting the laterite nickel ore leaching slag, a step of granulating the laterite nickel ore leaching slag is included. Granulation can increase the air permeability during roasting, facilitate ore feeding and ore discharge during operation, help desulfurization, and reduce the generation of smoke during the smelting process.

[0007] Optionally, a binder is added to the laterite nickel ore leaching residue for granulation, and the amount of the binder added is 0.5% to 1% of the mass of the laterite nickel ore leaching residue; further optionally, the binder includes at least one of bentonite, polyvinyl alcohol, and flour.

[0008] Optionally, in step S1, the roasting temperature is 850-900°C and the time is 15-45min. When the roasting temperature is lower than 850°C, the desulfurization rate of the leached slag is low; when the roasting temperature is higher than 900°C, the increased temperature has little effect on the desulfurization rate of the leached slag, but it will increase the energy consumption of the desulfurization section of the leached slag. When the roasting time is between 15 and 45min, the desulfurization rate of the leached slag can reach more than 98% under a weak reducing atmosphere, but extending the roasting time will also increase the energy consumption of the desulfurization section of the leached slag. When the roasting time is about 30min, the fixed carbon of the first reducing agent is basically reacted completely, and at the same time, the leached slag is reduced to produce part of FeO. During the reduction smelting process, the presence of FeO in the roasted sand is conducive to reducing the formation temperature of the initial liquid phase. As the reduction smelting temperature increases, the amount of liquid phase generated in the system increases; as the reduction reaction proceeds, the FeO content increases step by step, and the liquid phase viscosity decreases accordingly.

[0009] Optionally, in step S2, the smelting temperature is 1450-1550° C. and the smelting time is 15-45 min.

[0010] Optionally, in step S2, the second reducing agent includes a solid reducing agent and / or a gaseous reducing agent; when the amount of the second reducing agent is only measured as the solid reducing agent, the amount of the second reducing agent is 14% to 22% of the mass of the roasted sand; when the amount of the second reducing agent is only measured as the gaseous reducing agent, under standard atmospheric pressure, the volume mass ratio of the amount of the second reducing agent introduced to the roasted sand is 200 to 300 m 3 / t.

[0011] Optionally, the first reducing agent includes at least one of coal powder, coke, lignite, and activated carbon.

[0012] Optionally, the particle size of the first reducing agent is ≤1 mm. Since the particle size of the laterite nickel ore leaching residue itself is less than 200 mesh, a smaller particle size of the first reducing agent is conducive to uniform mixing of the laterite nickel ore leaching residue and the first reducing agent.

[0013] Optionally, the second reducing agent includes at least one of coal powder, coke, lignite, activated carbon, hydrogen, natural gas, methane, and coal gas; optionally, the particle size of the coal powder, coke, lignite, and activated carbon is ≤5mm; further optionally, the fixed carbon content of the coal powder, coke, lignite, and activated carbon is greater than 75%.

[0014] Optionally, the roasted sand obtained in step S1 is directly transported from the equipment for roasting to the equipment for smelting.

[0015] Optionally, the method further includes the step of removing dust from the sulfur-containing tail gas to obtain roasting dust and sulfur-containing flue gas; optionally, the roasting dust is used as a raw material in a roasting step; optionally, the sulfur-containing flue gas is used to prepare sulfuric acid.

[0016] Optionally, the method further includes a step of purifying the coal gas, wherein the purified coal gas is used to provide heat for the roasting in step S1 and / or is used as a second reducing agent.

[0017] Optionally, the laterite nickel ore leaching residue is the sulfur-containing iron slag produced after nickel and cobalt are extracted from limonite-type laterite nickel ore using a high-pressure acid leaching process. The laterite nickel ore leaching residue can be purchased or obtained by processing laterite nickel ore by itself. Typically, the specific process flow for processing laterite nickel ore includes: using limonite-type laterite nickel ore as raw material and sulfuric acid as leaching agent; laterite nickel ore particle size 60-150 mesh, acid-ore ratio 250-300g / kg, liquid-solid volume mass ratio 2.5:1-3.5:1 (unit: mL / g); laterite nickel ore is mixed with sulfuric acid solution and placed in an autoclave. High-pressure acid leaching: leaching temperature 230-260℃, pressure 4-5MPa, stirring rate 400-650r / min, leaching time 1-1.5h, and ore pulp is obtained after the leaching reaction is completed. Slurry flash evaporation: When the slurry is cooled to below 60°C, solid-liquid separation is carried out to obtain leaching solution and laterite nickel ore leaching residue. Washing and drying: After washing, the laterite nickel ore leaching residue is dried at a drying temperature of 100-120°C and a drying time of 2-5 hours; drying the laterite nickel ore leaching residue is mainly to remove its free water, and its free water content is about 20%-30%.

[0018] Optionally, in step S1, the equipment for roasting includes a roasting kiln or a rotary kiln.

[0019] Optionally, in step S2, the equipment for smelting includes a side-blown furnace or an electric furnace.

[0020] In the recovery method provided by the present invention, the sulfur content in the laterite nickel ore leaching residue is 1.0% to 4.0%, the calcium content is less than 0.5%, and the iron content is 40% to 60%.

[0021] In the recovery method provided by the present invention, the obtained sulfur-containing flue gas can be used to produce sulfuric acid, the obtained molten iron can be directly used for steelmaking, and the obtained smelting slag can be used to prepare green building materials.

[0022] The beneficial effects of the present invention are:

[0023] The invention provides a method for recovering laterite nickel ore leaching slag, comprising the following steps: S1: roasting the laterite nickel ore leaching slag in the presence of a first reducing agent to obtain roasted sand and sulfur-containing tail gas; S2: smelting the roasted sand obtained in S1 in the presence of a second reducing agent to obtain molten iron, smelting slag and coal gas; the laterite nickel ore leaching slag is in a dry state; the smelting slag is a MgO-Al2O3-SiO2-FeO slag system; the ratio of the total mass of fixed carbon in the first reducing agent to the total mass of sulfur in the laterite nickel ore leaching slag is 0.35-0.50. The present recovery method can comprehensively recover iron and sulfur in laterite nickel ore leaching slag without the need for additional flux, and the desulfurization rate of laterite nickel ore leaching slag roasting is greater than 95%, the grade of the obtained molten iron is greater than 96%, the sulfur content is less than 0.03%, the iron recovery rate is greater than 85%, and the iron content in the smelting slag is less than 5%; the obtained sulfur-containing flue gas can be used to make sulfuric acid, the obtained molten iron can be directly used for steelmaking, and the obtained smelting slag can be used to prepare green building materials, realizing the resource utilization of laterite nickel ore high-pressure leaching slag under the condition of low overall process cost, which is convenient for large-scale industrial use. The present recovery method is aimed at laterite nickel ore leaching slag, and by controlling the amount of the first reducing agent added during the roasting process, the laterite nickel ore leaching slag can be fully desulfurized, and the sulfur content in the roasted sand is controlled to be low. At the same time, there is a certain amount of FeO in the roasted sand. During the reduction smelting process, the presence of FeO in the roasted sand is beneficial to lowering the formation temperature of the initial liquid phase; using FeO as an alkaline component to participate in slag making and constructing a MgO-Al2O3-SiO2-FeO slag system smelting slag can reduce the melting point and viscosity of the slag, so that the smelting step does not require the addition of additional flux, reducing the amount of slag, reducing energy consumption in the overall process, and improving the economic efficiency of resource recovery of leached slag.

[0024] In the method for recovering laterite nickel ore leaching residue provided by the present invention, the roasted sand obtained in step S1 is directly transported from the roasting equipment to the smelting equipment, which can effectively avoid heat loss and reduce heat input during the reduction smelting process.

[0025] The method for recovering laterite nickel ore leaching residue provided by the present invention further includes a step of purifying the coal gas, and the purified coal gas is used to provide heat for the roasting in step S1, thereby achieving full utilization of the product in the process flow.

[0026] The method for recovering laterite nickel ore leaching residue provided by the present invention also includes the step of removing dust from the sulfur-containing tail gas to obtain roasting dust and sulfur-containing flue gas; the roasting dust is used as a raw material in the granulation step to achieve further recovery of iron and sulfur. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 The process flow chart of the method for recovering laterite nickel ore leaching residue in Example 1 of the present invention is shown. DETAILED DESCRIPTION

[0029] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0030] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0031] Experimental raw materials

[0032] Laterite nickel ore high-pressure leaching residue: the laterite nickel ore high-pressure leaching residue directly purchased is the sulfur-containing iron slag produced after nickel and cobalt are extracted from limonite-type laterite nickel ore using a high-pressure acid leaching process. It contains 41.75% iron, 2.11% chromium, 6.10% silicon, 3.94% aluminum, 0.70% magnesium, and 3.57% sulfur. The iron is mainly produced in the form of hematite, with a distribution rate of 98.63%, and the sulfur mainly exists in the form of sulfate, with a distribution rate of 94.96%; it is dried before use.

[0033] Anthracite: fixed carbon content 78.39%.

[0034] Coke: fixed carbon content 86.46%.

[0035] Blue carbon: fixed carbon content 77.28%.

[0036] Coke powder: fixed carbon content 86.20%.

[0037] Data calculation and testing

[0038] The calculation formula of desulfurization rate (η1) is as follows:

[0039]

[0040] Where: η1 is the desulfurization rate, %; S0 is the mass fraction of sulfur in the high-pressure leaching residue of laterite nickel ore, %; S1 is the mass fraction of sulfur in the roasted sand sample, %.

[0041] The calculation formula of iron recovery rate (η2) is as follows:

[0042]

[0043] In the formula: η2 is the recovery rate of iron, %; m1 is the mass of the metal obtained by roasted sand reduction smelting, g; w1 is the percentage of iron in the metal obtained by roasted sand reduction smelting, %; m0 is the mass of roasted sand, g; w0 is the total iron content in roasted sand, %.

[0044] The determination of sulfur content in roasted sand shall refer to GB223.72-2008, and the determination of FeO content shall refer to GB / T14506.14-2010; the determination of iron content in molten iron shall refer to GB / T 223.70-2008, the determination of sulfur content shall refer to GB223.72-2008, and the determination of iron content in smelting slag shall refer to GB / T 6730.6-2016.

[0045] Example 1

[0046] This embodiment provides a method for recovering laterite nickel ore leaching residue, and its flow diagram is shown in Figure 1 , specifically including the following steps:

[0047] (1) Take the high-pressure leaching residue of laterite nickel ore and 1.7% of its mass anthracite (crushed to a particle size of about 0.5 mm), then add 0.6% of its mass flour to mix, and use a disc ball making machine to make balls (inclination angle 45°, speed 30r / min), the whole ball making process is controlled within 20 minutes, the amount of water added is controlled to be 17% (calculated as the percentage of the mass of water to the laterite nickel ore), and the obtained green balls are dried in a 110°C blast drying oven for 7 hours to obtain dry balls. The dry balls are sent to a roasting kiln and roasted at 900°C for 45 minutes to obtain roasted sand and sulfur-containing tail gas; the sulfur-containing tail gas is dedusted to obtain roasting dust and sulfur-containing flue gas, and the roasting dust is returned to the roasting kiln as a raw material to participate in the roasting process.

[0048] (2) The roasted sand obtained in (1) is quickly transferred to a side-blown furnace, and 16% by weight of anthracite (crushed to a particle size of ≤5 mm) is added thereto. The furnace is smelted at 1500°C for 20 minutes to obtain molten iron, smelting slag and coal gas. The coal gas is purified and used to supplement the heat of the roasting kiln in (1).

[0049] The roasted sand obtained in step (1) has a sulfur content of 0.039% and a FeO content of 0.13%.

[0050] The molten iron obtained in step (2) has an iron content of 98.81% and a sulfur content of 0.017%.

[0051] The iron content in the smelting slag obtained in step (2) is 3.78%.

[0052] The smelting slag obtained in step (2) belongs to the MgO-Al2O3-SiO2-FeO slag system.

[0053] The iron recovery rate is 91.52%, and the desulfurization rate of the laterite nickel ore leaching residue roasting is 98.91%.

[0054] The sulfur-containing flue gas obtained can be used to produce sulfuric acid, the molten iron can be directly used in the steelmaking process, and the smelting slag can be used as a raw material for building materials after water quenching.

[0055] Example 2

[0056] This embodiment provides a method for recovering laterite nickel ore leaching residue, and its flow diagram is shown in Figure 1 , specifically including the following steps:

[0057] (1) Take the high-pressure leaching residue of laterite nickel ore and 2.0% of anthracite (crushed to a particle size of about 0.5 mm), add 0.5% of polyvinyl alcohol, and mix them. Use a disc pelletizer to make balls (inclination angle 45°, rotation speed 30r / min), the whole ball making process is controlled within 20 minutes, the amount of water added is controlled to be 17% (the mass of water accounts for the percentage of laterite nickel ore), and the obtained green balls are dried in a 110°C blast drying oven for 7 hours to obtain dry balls. The dry balls are sent to a roasting kiln and roasted at 850°C for 45 minutes to obtain roasted sand and sulfur-containing tail gas; the sulfur-containing tail gas is dedusted to obtain roasting dust and sulfur-containing flue gas, and the roasting dust is returned to the roasting kiln as a raw material to participate in the roasting process.

[0058] (2) The roasted sand obtained in (1) is quickly transferred to a side-blown furnace, and 15% by weight of anthracite (crushed to a particle size of ≤1 mm) is added thereto. The furnace is smelted at 1500°C for 40 minutes to obtain molten iron, smelting slag and coal gas. The coal gas is purified and used to supplement the heat of the roasting kiln in (1).

[0059] The roasted sand obtained in step (1) has a sulfur content of 0.097% and a FeO content of 1.31%.

[0060] The molten iron obtained in step (2) has an iron content of 98.19% and a sulfur content of 0.020%.

[0061] The iron content in the smelting slag obtained in step (2) is 4.58%.

[0062] The smelting slag obtained in step (2) belongs to the MgO-Al2O3-SiO2-FeO slag system.

[0063] The iron recovery rate is 90.85%, and the desulfurization rate of the laterite nickel ore leaching residue roasting is 97.28%.

[0064] The sulfur-containing flue gas obtained can be used to produce sulfuric acid, the molten iron can be directly used in the steelmaking process, and the smelting slag can be used as a raw material for building materials after water quenching.

[0065] Example 3

[0066] This embodiment provides a method for recovering laterite nickel ore leaching residue, and its flow diagram is shown in Figure 1 , specifically including the following steps:

[0067] (1) Take the high-pressure leaching residue of laterite nickel ore and 1.8% of anthracite (crushed to a particle size of about 0.5 mm), add 0.7% of bentonite, mix, and use a disc pelletizer to make balls (inclination angle 45°, rotation speed 30r / min), the whole ball making process is controlled within 20 minutes, the amount of water added is controlled to be 17% (the percentage of water mass to laterite nickel ore), and the obtained green balls are dried in a 110°C blast drying oven for 7 hours to obtain dry balls. The dry balls are sent to a roasting kiln and roasted at 900°C for 30 minutes to obtain roasted sand and sulfur-containing tail gas; the sulfur-containing tail gas is dedusted to obtain roasting dust and sulfur-containing flue gas, and the roasting dust is returned to the roasting kiln as a raw material to participate in the roasting process.

[0068] (2) The roasted sand obtained in (1) is quickly transferred to a side-blown furnace, and 16% by weight of anthracite (crushed to a particle size of ≤1 mm) is added thereto. The furnace is smelted at 1450° C. for 20 min to obtain molten iron, smelting slag and coal gas. The coal gas is purified and used to supplement the heat of the roasting kiln in (1).

[0069] The roasted sand obtained in step (1) has a sulfur content of 0.035% and a FeO content of 0.20%.

[0070] The molten iron obtained in step (2) has an iron content of 96.91% and a sulfur content of 0.019%.

[0071] The iron content in the smelting slag obtained in step (2) is 4.06%.

[0072] The smelting slag obtained in step (2) belongs to the MgO-Al2O3-SiO2-FeO slag system.

[0073] The iron recovery rate is 89.85%, and the desulfurization rate of the laterite nickel ore leaching residue roasting is 99.02%.

[0074] The sulfur-containing flue gas obtained can be used to produce sulfuric acid, the molten iron can be directly used in the steelmaking process, and the smelting slag can be used as a raw material for building materials after water quenching.

[0075] Example 4

[0076] This embodiment provides a method for recovering laterite nickel ore leaching residue, and its flow diagram is shown in Figure 1 , specifically including the following steps:

[0077] (1) Take the high-pressure leaching residue of laterite nickel ore and 2.2% of anthracite (crushed to a particle size of about 0.5 mm), add 0.8% of bentonite, mix, and use a disc ball making machine to make balls (inclination angle 45°, speed 30r / min), the whole ball making process is controlled within 20 minutes, the amount of water added is controlled to be 16-18% (the mass of water accounts for the percentage of laterite nickel ore), and the obtained green balls are dried in a 110°C blast drying oven for 6-8 hours to obtain dry balls. The dry balls are sent to a roasting kiln and roasted at 870°C for 25 minutes to obtain roasted sand and sulfur-containing tail gas; the sulfur-containing tail gas is dedusted to obtain roasting dust and sulfur-containing flue gas, and the roasting dust is returned to the roasting kiln as a raw material to participate in the roasting process.

[0078] (2) The roasted sand obtained in (1) is quickly transferred to a side-blown furnace, and 16% by weight of anthracite (crushed to a particle size of ≤1 mm) is added thereto. The furnace is smelted at 1450° C. for 20 min to obtain molten iron, smelting slag and coal gas. The coal gas is purified and used to supplement the heat of the roasting kiln in (1).

[0079] The roasted sand obtained in step (1) has a sulfur content of 0.102% and a FeO content of 3.80%.

[0080] The molten iron obtained in step (2) has an iron content of 96.72% and a sulfur content of 0.029%.

[0081] The iron content in the smelting slag obtained in step (2) is 4.21%.

[0082] The smelting slag obtained in step (2) belongs to the MgO-Al2O3-SiO2-FeO slag system.

[0083] The iron recovery rate is 89.86%, and the desulfurization rate of the laterite nickel ore leaching residue roasting is 97.14%.

[0084] The sulfur-containing flue gas obtained can be used to produce sulfuric acid, the molten iron can be directly used in the steelmaking process, and the smelting slag can be used as a raw material for building materials after water quenching.

[0085] Example 5

[0086] This embodiment provides a method for recovering laterite nickel ore leaching residue, and its flow diagram is shown in Figure 1 , specifically including the following steps:

[0087] (1) Take the high-pressure leaching residue of laterite nickel ore and 1.5% of coke (crushed to a particle size of about 0.5 mm) by weight, add 1.0% of bentonite by weight and mix, and use a disc pelletizer to make balls (inclination angle 45°, rotation speed 30r / min), the whole ball making process is controlled within 20 minutes, the amount of water added is controlled to be 17% (the mass of water accounts for the percentage of laterite nickel ore), and the obtained green balls are dried in a 110°C blast drying oven for 7 hours to obtain dry pellets. The dry pellets are sent to a roasting kiln and roasted at 900°C for 15 minutes to obtain roasted sand and sulfur-containing tail gas; the sulfur-containing tail gas is dedusted to obtain roasting dust and sulfur-containing flue gas, and the roasting dust is returned to the roasting kiln as a raw material to participate in the roasting process.

[0088] (2) The roasted sand obtained in (1) is quickly transferred to a side-blown furnace, and 22% by weight of blue carbon (crushed to a particle size of ≤5 mm) is added thereto. The furnace is smelted at 1450°C for 45 minutes to obtain molten iron, smelting slag and coal gas. The coal gas is purified and used to supplement the heat of the roasting kiln in (1).

[0089] The roasted sand obtained in step (1) has a sulfur content of 0.036% and a FeO content of 0.18%.

[0090] The molten iron obtained in step (2) has an iron content of 96.12% and a sulfur content of 0.028%.

[0091] The iron content in the smelting slag obtained in step (2) is 4.78%.

[0092] The smelting slag obtained in step (2) belongs to the MgO-Al2O3-SiO2-FeO slag system.

[0093] The iron recovery rate is 89.49%, and the desulfurization rate of the laterite nickel ore leaching residue roasting is 98.99%.

[0094] The sulfur-containing flue gas obtained can be used to produce sulfuric acid, the molten iron can be directly used in the steelmaking process, and the smelting slag can be used as a raw material for building materials after water quenching.

[0095] Example 6

[0096] This embodiment provides a method for recovering laterite nickel ore leaching residue, and its flow diagram is shown in Figure 1 , specifically including the following steps:

[0097] (1) Take the high-pressure leaching residue of laterite nickel ore and 2.3% of its mass of blue carbon (crushed to a particle size of about 0.5 mm), then add 0.7% of its mass of bentonite to mix, and use a disc ball making machine to make balls (inclination angle 45°, speed 30r / min), the whole ball making process is controlled within 20 minutes, the amount of water added is controlled to be 17% (the mass of water accounts for the percentage of laterite nickel ore), and the obtained green balls are dried in a 110°C blast drying oven for 7 hours to obtain dry pellets. The dry pellets are sent to a roasting kiln and roasted at 875°C for 45 minutes to obtain roasted sand and sulfur-containing tail gas; the sulfur-containing tail gas is dedusted to obtain roasting dust and sulfur-containing flue gas, and the roasting dust is returned to the roasting kiln as a raw material to participate in the roasting process.

[0098] (2) The roasted sand obtained in (1) is quickly transferred to a side-blown furnace, and coke powder (particle size ≤ 1 mm) of 14% by weight is added thereto. The roasted sand is smelted at 1550°C for 15 minutes to obtain molten iron, smelting slag and coal gas. The coal gas is purified and used to supplement the heat of the roasting kiln in (1).

[0099] The roasted sand obtained in step (1) has a sulfur content of 0.089% and a FeO content of 3.71%.

[0100] The molten iron obtained in step (2) has an iron content of 97.32% and a sulfur content of 0.026%.

[0101] The iron content of the smelting slag obtained in step (2) is 3.91%.

[0102] The smelting slag obtained in step (2) belongs to the MgO-Al2O3-SiO2-FeO slag system.

[0103] The iron recovery rate is 90.19%, and the desulfurization rate of the laterite nickel ore leaching residue roasting is 97.51%.

[0104] The sulfur-containing flue gas obtained can be used to produce sulfuric acid, the molten iron can be directly used in the steelmaking process, and the smelting slag can be used as a raw material for building materials after water quenching.

[0105] Example 7

[0106] This embodiment provides a method for recovering laterite nickel ore leaching residue, which specifically comprises the following steps:

[0107] (1) Take the high-pressure leaching residue of laterite nickel ore and 2.0% of anthracite (crushed to a particle size of about 0.5 mm) by weight, add 0.5% of bentonite by weight and mix, and use a disc ball making machine to make balls (inclination angle 45°, speed 30r / min), the whole ball making process is controlled within 20 minutes, the amount of water added is controlled to be 17% (the mass of water accounts for the percentage of laterite nickel ore), and the obtained green balls are dried in a 110°C blast drying oven for 7 hours to obtain dry balls. The dry balls are sent to a roasting kiln and roasted at 850°C for 45 minutes to obtain roasted sand and sulfur-containing tail gas; the sulfur-containing tail gas is dedusted to obtain roasting dust and sulfur-containing flue gas, and the roasting dust is returned to the roasting kiln as a raw material to participate in the roasting process.

[0108] (2) The roasted sand obtained in (1) is quickly transferred to a side-blown furnace, and a liquid having a volume mass ratio of 200 m 3 / t of natural gas is smelted at 1550℃ for 15min to obtain molten iron, smelting slag and coal gas. The coal gas is purified and used to supplement the heat of the roasting kiln in (1).

[0109] The roasted sand obtained in step (1) has a sulfur content of 0.097% and a FeO content of 1.31%.

[0110] The molten iron obtained in step (2) has an iron content of 96.17% and a sulfur content of 0.023%.

[0111] The iron content in the smelting slag obtained in step (2) is 4.85%.

[0112] The smelting slag obtained in step (2) belongs to the MgO-Al2O3-SiO2-FeO slag system.

[0113] The iron recovery rate is 89.15%, and the desulfurization rate of the laterite nickel ore leaching residue roasting is 97.28%.

[0114] The sulfur-containing flue gas obtained can be used to produce sulfuric acid, the molten iron can be directly used in the steelmaking process, and the smelting slag can be used as a raw material for building materials after water quenching.

[0115] Example 8

[0116] This embodiment provides a method for recovering laterite nickel ore leaching residue, which specifically comprises the following steps:

[0117] (1) Take the high-pressure leaching residue of laterite nickel ore and 2.0% of anthracite (crushed to a particle size of about 0.5 mm), add 1.0% of bentonite, mix, and use a disc pelletizer to make balls (inclination angle 45°, rotation speed 30r / min), the whole ball making process is controlled within 20 minutes, the amount of water added is controlled to be 17% (the mass of water accounts for the percentage of laterite nickel ore), and the obtained green balls are dried in a 110°C blast drying oven for 7 hours to obtain dry balls. The dry balls are sent to a roasting kiln and roasted at 850°C for 45 minutes to obtain roasted sand and sulfur-containing tail gas; the sulfur-containing tail gas is dedusted to obtain roasting dust and sulfur-containing flue gas, and the roasting dust is returned to the roasting kiln as a raw material to participate in the roasting process.

[0118] (2) The roasted sand obtained in (1) is quickly transferred to a side-blown furnace, and a liquid having a volume mass ratio of 300 m 3 / t of coal gas is smelted at 1550℃ for 15min to obtain molten iron, smelting slag and coal gas. The coal gas is purified and returned for use as the second reducing agent.

[0119] The roasted sand obtained in step (1) has a sulfur content of 0.097% and a FeO content of 1.31%.

[0120] The molten iron obtained in step (2) has an iron content of 97.24% and a sulfur content of 0.027%.

[0121] The iron content in the smelting slag obtained in step (2) is 2.47%.

[0122] The smelting slag obtained in step (2) belongs to the MgO-Al2O3-SiO2-FeO slag system.

[0123] The iron recovery rate is 90.10%, and the desulfurization rate of the laterite nickel ore leaching residue roasting is 97.28%.

[0124] The sulfur-containing flue gas obtained can be used to produce sulfuric acid, the molten iron can be directly used in the steelmaking process, and the smelting slag can be used as a raw material for building materials after water quenching.

[0125] Comparative Example 1

[0126] This comparative example provides a method for recovering laterite nickel ore leaching residue. Compared with Example 5, the only difference is that in step (1), coke accounting for 1% of the mass of the laterite nickel ore high-pressure leaching residue is used.

[0127] The roasted sand obtained in step (1) has a sulfur content of 0.58% and an FeO content that is not detected.

[0128] The molten iron obtained in step (2) has an iron content of 95.17% and a sulfur content of 0.928%.

[0129] The iron content of the smelting slag obtained in step (2) is 5.03%.

[0130] The smelting slag obtained in step (2) belongs to the MgO-Al2O3-SiO2-FeO slag system.

[0131] The iron recovery rate is 88.47%, and the desulfurization rate of the laterite nickel ore leaching residue roasting is 83.75%.

[0132] Comparative Example 2

[0133] This comparative example provides a method for recovering laterite nickel ore leaching residue. Compared with Example 6, the only difference is that in step (1), 3.5% of the mass of blue carbon of laterite nickel ore high-pressure leaching residue is used.

[0134] The roasted sand obtained in step (1) has a sulfur content of 0.47% and a FeO content of 15.10%.

[0135] The molten iron obtained in step (2) has an iron content of 95.34% and a sulfur content of 0.787%.

[0136] The iron content in the smelting slag obtained in step (2) is 4.58%.

[0137] The smelting slag obtained in step (2) belongs to the MgO-Al2O3-SiO2-FeO slag system.

[0138] The iron recovery rate is 87.67%, and the desulfurization rate of the laterite nickel ore leaching residue roasting is 86.83%.

[0139] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the protection scope of the invention.

Claims

1. A method for recovering laterite nickel ore leaching residue, characterized in that: The steps include: S1: roasting laterite nickel ore leaching residue in the presence of a first reducing agent to obtain roasted sand and sulfur-containing tail gas; S2: In the presence of a second reducing agent, smelting the roasted sand obtained in S1 to obtain molten iron, smelting slag and coal gas; The laterite nickel ore leaching residue is in a dry state; The smelting slag is a MgO-Al2O3-SiO2-FeO slag system; The total mass ratio of the fixed carbon in the first reducing agent to the total mass ratio of the sulfur in the laterite nickel ore leaching residue is 0.35 to 0.

50.

2. The recycling method according to claim 1, characterized in that: In the step S1, before roasting the laterite nickel ore leaching residue, a step of granulating the laterite nickel ore leaching residue is included; optionally, a binder is added to the laterite nickel ore leaching residue for granulation, and the amount of the binder added is 0.5% to 1% of the mass of the laterite nickel ore leaching residue; further optionally, the binder includes at least one of bentonite, polyvinyl alcohol, and flour.

3. The recovery method according to claim 1 or 2, characterized in that: In the step S1, the calcination temperature is 850-900°C and the calcination time is 15-45 minutes; And / or, in step S2, the smelting temperature is 1450-1550° C. and the smelting time is 15-45 min.

4. The recycling method according to any one of claims 1 to 3, characterized in that: In step S2, the second reducing agent includes a solid reducing agent and / or a gaseous reducing agent; When the amount of the second reducing agent is measured only as a solid reducing agent, the amount of the second reducing agent is 14% to 22% of the mass of the roasted sand; When the amount of the second reducing agent is measured only as a gaseous reducing agent, the volume mass ratio of the amount of the second reducing agent introduced to the roasted sand is 200 to 300 m 3 / t.

5. The recycling method according to any one of claims 1 to 4, characterized in that: The first reducing agent includes at least one of coal powder, coke, blue carbon, and activated carbon; optionally, the particle size of the first reducing agent is ≤1 mm; And / or, the second reducing agent includes at least one of coal powder, coke, lignite, activated carbon, hydrogen, natural gas, methane, and coal gas; optionally, the particle size of the coal powder, coke, lignite, and activated carbon is ≤5mm; further optionally, the fixed carbon content of the coal powder, coke, lignite, and activated carbon is ≥75%.

6. The recycling method according to any one of claims 1 to 5, characterized in that: The roasted sand obtained in step S1 is directly transported from the roasting equipment to the smelting equipment.

7. The recycling method according to any one of claims 1 to 6, characterized in that: The method further comprises the step of removing dust from the sulfur-containing tail gas to obtain roasting dust and sulfur-containing flue gas; optionally, the roasting dust is used as a raw material in a roasting step; optionally, the sulfur-containing flue gas is used to prepare sulfuric acid.

8. The recycling method according to any one of claims 1 to 7, characterized in that: The method further comprises a step of purifying the coal gas, wherein the purified coal gas is used to provide heat for the roasting in step S1 and / or is used as a second reducing agent.

9. The recycling method according to any one of claims 1 to 8, characterized in that: The laterite nickel ore leaching residue is a sulfur-containing iron slag produced after nickel and cobalt are extracted from limonite-type laterite nickel ore using a high-pressure acid leaching process.

10. The recycling method according to any one of claims 1 to 9, characterized in that: In the step S1, the equipment for roasting includes a roasting kiln or a rotary kiln; And / or, in step S2, the equipment for smelting includes a side-blown furnace or an electric furnace.

Images