Method and system for resource utilization of laterite nickel ore leaching tailings

Abstract

The invention discloses a method and system for resource utilization of laterite nickel ore leaching tailings. The method comprises: mixing the laterite nickel ore leaching tailings with a flux to obtain a mixed material; subjecting the mixed material to smelting slag desulfurization to obtain molten slag and flue gas containing SO2; and mixing the molten slag with a reducing agent to perform reduction and iron extraction to obtain molten iron, iron extraction slag and coal gas. The method can solve the environmental hazard problem of laterite nickel ore leaching tailings, comprehensively utilize the valuable elements such as iron and sulfur therein, generate considerable economic benefits, and has low energy consumption, low production cost, simple process, easy operation, suitable for large-scale production, and high practical value.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste utilization, and specifically relates to a method and system for resource utilization of laterite nickel ore leaching tailings. Background Art

[0002] Nickel has the characteristics of high mechanical strength, good ductility, high temperature resistance, and high chemical stability. It is widely used in stainless steel, new energy and other fields, and has become an indispensable metal in today's society. In recent years, with the advancement of technology, the use of pressurized sulfuric acid leaching process to treat high-iron and low-magnesium laterite nickel ore to recover nickel and cobalt has attracted much attention, and its production capacity has increased year by year.

[0003] The biggest bottleneck of wet leaching of laterite nickel ore is the large amount of tailings. The iron in the tailings is mainly in the form of hematite. Due to its high water content, low grade and high sulfur content, it cannot be sold directly to steel mills as an ironmaking raw material. There is currently no industrial example of comprehensive recycling and utilization. It is basically treated in a stockpiling manner, which has extremely high environmental safety risks. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, one purpose of the present invention is to provide a method and system for resource utilization of laterite nickel ore leaching tailings, which can not only solve the environmental protection hidden dangers of laterite nickel ore leaching tailings, but also comprehensively utilize valuable elements such as iron and sulfur therein to generate considerable economic benefits.

[0005] In a first aspect of the present invention, the present invention proposes a method for resource utilization of laterite nickel ore leaching tailings. According to an embodiment of the present invention, the method comprises:

[0006] (1) mixing the laterite nickel ore leaching tailings with a flux to obtain a mixed material;

[0007] (2) subjecting the mixed material to slag desulfurization to obtain slag and SO 2 of smoke;

[0008] (3) The molten slag is mixed with a reducing agent to reduce and extract iron, so as to obtain molten iron, iron-extracting slag and coal gas.

[0009] According to the method for resource utilization of laterite nickel ore leaching tailings of the above embodiment of the present invention, the laterite nickel ore leaching tailings are used as raw materials to solve the environmental protection potential problems of laterite nickel ore leaching tailings, the laterite nickel ore leaching tailings are mixed with a flux to obtain a mixed material, and the mixed material is melted and slag-made and desulfurized to obtain molten slag and SO-containing 2 The flue gas contains SO 2The flue gas can be used for acid production, realizing the comprehensive utilization of sulfur in the tailings of laterite nickel ore leaching. The slag can be reduced to extract iron to obtain molten iron, iron slag and coal gas. The molten iron can be used for steelmaking, realizing the comprehensive utilization of iron in the tailings of laterite nickel ore leaching. The iron slag can be used to prepare building materials, and the coal gas can be used as fuel, thereby generating objective economic benefits. In addition, mixing the tailings of laterite nickel ore leaching with flux before molten slag desulfurization can directly adjust the internal structure and chemical composition of the slag, improve the metallurgical properties of the slag, reduce the temperature of reduction and iron extraction, and facilitate the subsequent reduction and iron extraction. In addition, the molten slag desulfurization and the reduction iron extraction are carried out separately. On the one hand, since the heat required for molten slag desulfurization is more, the heat required for reduction iron extraction is less, which can reduce energy consumption and reduce production and operation costs. On the other hand, the use of a weak reducing atmosphere for desulfurization and melting is conducive to the decomposition of gypsum, and solves the problem that the reducing agent ratio range is narrow during conventional reduction desulfurization (too much or too little reducing agent is not conducive to desulfurization), it is difficult to adapt to the problem of fluctuations in the composition of the tailings of laterite nickel ore leaching, and the problem of adhesion caused by the excessively high reduction desulfurization temperature. Therefore, the method can solve the environmental protection hidden dangers of the tailings of laterite nickel ore leaching, comprehensively utilize the valuable elements such as iron and sulfur therein, generate considerable economic benefits, and have low energy consumption, low production cost, simple process, easy operation, suitable for large-scale production, and high practical value.

[0010] In addition, the method for resource utilization of laterite nickel ore leaching tailings according to the above embodiment of the present invention may also have the following additional technical features:

[0011] In some embodiments of the present invention, the laterite nickel ore leaching tailings are pre-dried before being mixed with flux, which is beneficial for subsequent batching and transportation.

[0012] In some embodiments of the present invention, in step (1), the laterite nickel ore leaching tailings are mixed with the flux and then dried and crushed, thereby improving the efficiency of subsequent slag-making and desulfurization and reducing the energy consumption of chemical materials.

[0013] In some embodiments of the present invention, in step (1), the flux contains CaO and MgO, which is beneficial to the reduction and extraction of iron.

[0014] In some embodiments of the present invention, in step (1), the mixing ratio of the laterite nickel ore leaching tailings and the flux is based on the ratio of CaO to SiO in the iron ore slag. 2 The mass ratio of MgO to MgO is (0.9-1.2):1, and the content of MgO in the iron extraction slag is 6wt%-10wt%. This is conducive to the reduction of iron.

[0015] In some embodiments of the present invention, in step (2), the temperature of the molten slag desulfurization is 1500°C-1550°C.

[0016] In some embodiments of the present invention, during the molten slag desulfurization process, the ends of the first fuel spray gun and the mixture spray gun are extended below the slag, thereby facilitating the molten slag desulfurization.

[0017] In some embodiments of the present invention, the combustion-supporting air used by the first fuel spray gun includes oxygen-enriched air, the oxygen concentration of the oxygen-enriched air is not less than 65 vol%, and the air excess coefficient is 0.95-0.98.

[0018] In some embodiments of the present invention, in step (3), the temperature of the reduction and iron extraction is 1400°C-1500°C.

[0019] In some embodiments of the present invention, during the reduction and iron extraction process, the tip of the second fuel lance is extended below the slag layer, thereby facilitating the reduction and iron extraction process.

[0020] In some embodiments of the present invention, supplementary heat is provided for the reduction and iron production via a third fuel injection gun and / or an electrode.

[0021] In some embodiments of the present invention, when the third fuel spray gun is used to provide supplementary heat for the reduction and iron extraction, the end of the third fuel spray gun is extended below the slag layer, and the volume of CO in the reaction system accounts for 1:1 of CO and CO. 2 The total volume content is not less than 80%. This can improve the reduction effect and reduce the iron content of the iron slag.

[0022] In some embodiments of the present invention, the mixed material is preheated before being subjected to smelting slag desulfurization, thereby improving the efficiency of subsequent smelting slag desulfurization and reducing the energy consumption of the material.

[0023] In some embodiments of the present invention, the temperature of the preheated mixed material is 500° C.-650° C. This can improve the efficiency of subsequent slag-making desulfurization, reduce the energy consumption of the smelting material, and avoid premature decomposition of sulfate.

[0024] In a second aspect of the present invention, the present invention proposes a system for resource utilization of laterite nickel ore leaching tailings. According to an embodiment of the present invention, the system comprises:

[0025] A mixing device, the mixing device having a laterite nickel ore leaching tailings inlet, a flux inlet and a mixed material outlet, and being suitable for mixing the laterite nickel ore leaching tailings with the flux to obtain a mixed material;

[0026] A smelting slag desulfurization device, the smelting slag desulfurization device having a mixed material inlet, a slag outlet and a flue gas outlet, the mixed material inlet is connected to the mixed material outlet, and is suitable for smelting slag desulfurization of the mixed material to obtain slag and SO 2 of smoke;

[0027] The reduction device comprises a slag inlet, a reducing agent inlet, a molten iron outlet, an iron-removing slag outlet, and a coal gas outlet. The slag inlet is connected to the slag outlet and is suitable for mixing the slag with the reducing agent to reduce and extract iron, so as to obtain molten iron, iron-removing slag and coal gas.

[0028] According to the system for resource utilization of laterite nickel ore leaching tailings of the above embodiment of the present invention, the laterite nickel ore leaching tailings are used as raw materials to solve the environmental hazards of laterite nickel ore leaching tailings. A mixing device is used to mix the laterite nickel ore leaching tailings with a flux to obtain a mixed material. The mixed material is subjected to molten slag desulfurization by a molten slag desulfurization device to obtain molten slag and SO-containing 2 The flue gas contains SO 2 The flue gas can be used for acid production, realizing the comprehensive utilization of sulfur in the laterite nickel ore leaching tailings. The slag can be reduced and iron-extracted by a reduction device to obtain molten iron, iron-extracted slag and coal gas. The obtained molten iron can be used for steelmaking, realizing the comprehensive utilization of iron in the laterite nickel ore leaching tailings. The obtained iron-extracted slag can be used to prepare building materials, and the obtained coal gas can be used as fuel, thereby generating objective economic benefits. In addition, a laterite nickel ore leaching tailings inlet, a flux inlet and a mixed material outlet are set on the mixing device, and a mixed material inlet connected to the mixed material outlet is set on the molten slag desulfurization device. The laterite nickel ore leaching tailings are mixed with the flux before the molten slag desulfurization, which can directly adjust the internal structure and chemical composition of the slag, improve the metallurgical properties of the slag, reduce the temperature of the reduction and iron extraction, and facilitate the subsequent reduction and iron extraction. In addition, the molten slag desulfurization and reduction iron extraction are carried out in different equipments. On the one hand, since the molten slag desulfurization requires more heat and the reduction iron extraction requires less heat, it can reduce energy consumption and reduce production and operation costs. On the other hand, the use of weak reducing atmosphere for desulfurization and melting is conducive to the decomposition of gypsum, and solves the problem of narrow reducing agent ratio range (too much or too little reducing agent is not conducive to desulfurization) in conventional reduction desulfurization, and it is difficult to adapt to the problem of fluctuation of the composition of laterite nickel ore leaching tailings, and the problem of adhesion caused by excessively high reduction desulfurization temperature. Therefore, the use of this system can solve the environmental protection hidden dangers of laterite nickel ore leaching tailings, comprehensively utilize the valuable elements such as iron and sulfur therein, generate considerable economic benefits, and have low energy consumption, low production cost, easy operation, suitable for large-scale production, and high practical value.

[0029] In addition, the system for resource utilization of laterite nickel ore leaching tailings according to the above embodiment of the present invention may also have the following additional technical features:

[0030] In some embodiments of the present invention, the system further comprises a pre-drying treatment device, the pre-drying treatment device having a laterite nickel ore leaching tailings inlet and a dried leaching tailings outlet, the dried leaching tailings outlet is connected to the laterite nickel ore leaching tailings inlet, and is suitable for pre-drying the laterite nickel ore leaching tailings before mixing the laterite nickel ore leaching tailings with flux, thereby facilitating subsequent batching and transportation.

[0031] In some embodiments of the present invention, the system further comprises a drying and crushing device, the drying and crushing device having an inlet for materials to be processed and an outlet for materials after drying and crushing, the inlet for materials to be processed is connected to the outlet for the mixed material, the outlet for materials after drying and crushing is connected to the inlet for the mixed material, and is suitable for drying and crushing the mixed material in advance before supplying the mixed material to the molten slag desulfurization device, and supplying the obtained dried and crushed mixed material to the molten slag desulfurization device. Thereby, the efficiency of subsequent molten slag desulfurization is improved and the energy consumption of chemical materials is reduced.

[0032] In some embodiments of the present invention, the system further includes: a preheating device, the preheating device having a mixed material inlet, a preheated material outlet and a preheated tail gas outlet, the mixed material inlet is connected to the mixed material outlet, the preheated material outlet is connected to the mixed material inlet, and is suitable for preheating the mixed material before supplying the mixed material to the molten slag desulfurization device, and supplying the obtained preheated mixed material to the molten slag desulfurization device; a dust collecting device, the dust collecting device having a preheated tail gas inlet, a dust collecting outlet and a tail gas outlet after dust collection, the preheated tail gas inlet is connected to the preheated tail gas outlet, the dust collecting outlet is connected to the mixed material inlet, and the tail gas outlet after dust collection is connected to the pre-drying treatment device. This is conducive to improving the efficiency of subsequent molten slag desulfurization and reducing the energy consumption of chemical materials.

[0033] In some embodiments of the present invention, the molten slag desulfurization device comprises: a molten slag desulfurization device body, which includes a furnace and a slag zone from top to bottom; a mixture material spray gun, the end of which extends into the slag zone; a first fuel spray gun, the end of which extends into the slag zone; a secondary air port, which is arranged in the furnace; a flue, which is connected to the furnace; and a slag outlet, which is arranged on the side wall of the slag zone. Thus, the comprehensive utilization of sulfur in the tailings of laterite nickel ore leaching is achieved.

[0034] In some embodiments of the present invention, the molten slag desulfurization device further comprises a flue gas waste heat recovery device, and the flue gas waste heat recovery device is connected to the flue, thereby improving the heat utilization rate of the entire process and reducing energy consumption.

[0035] In some embodiments of the present invention, the reduction device comprises: a reduction device body, wherein a reduction zone, a carburizing zone and a settling zone are arranged horizontally along the inner edge of the reduction device body, a partition wall is arranged between the carburizing zone and the settling zone, and there is a distance between the bottom end of the partition wall and the bottom of the reduction device body; a slag inlet, wherein the slag inlet is arranged in the reduction zone; a reducing agent spray gun, wherein the reducing agent spray gun is arranged in the reduction zone; a second fuel spray gun, wherein the second fuel spray gun is arranged in the reduction zone and the end of the second fuel spray gun extends below the slag layer of the reduction zone; a carburizing agent spray gun, wherein the carburizing agent spray gun is arranged in the carburizing zone and the end of the carburizing agent spray gun extends below the slag layer of the carburizing zone; and a supplementary heat device, wherein the supplementary heat device is arranged in the carburizing zone and the settling zone. Thus, the comprehensive utilization of the iron element in the tailings of laterite nickel ore leaching is achieved.

[0036] In some embodiments of the present invention, the system further comprises a coal gas utilization device, which is connected to the coal gas outlet, the pre-drying device, the preheating device and the molten slag desulfurization device, and is suitable for collecting the coal gas generated in the reduction device and supplying it to at least one of the pre-drying device, the preheating device and the molten slag desulfurization device for use as fuel. This can improve the utilization efficiency of the coal gas and the heat utilization rate of the entire process, thereby reducing energy consumption.

[0037] In some embodiments of the present invention, the distance between the top of the slag zone and the bottom of the slag-making desulfurization device body is not less than 800 mm, the distance between the end of the mixture spray gun and the top of the slag zone is not less than 200 mm, and the distance between the end of the first fuel spray gun and the top of the slag zone is not less than 200 mm. This is conducive to improving the melting efficiency.

[0038] In some embodiments of the present invention, the distance between the end of the second fuel lance and the top of the slag layer is not less than 200 mm, and the lance is located above the molten iron layer.

[0039] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0041] Figure 1This is a schematic flow chart of a method for resource utilization of laterite nickel ore leaching tailings according to an embodiment of the present invention;

[0042] Figure 2 This is a schematic diagram of a system structure for resource utilization of laterite nickel ore leaching tailings according to an embodiment of the present invention;

[0043] Figure 3 This is one of the structural schematic diagrams of a molten slag desulfurization device according to an embodiment of the present invention;

[0044] Figure 4 This is a second structural schematic diagram of a molten slag desulfurization device according to an embodiment of the present invention;

[0045] Figure 5 is a schematic structural diagram of a molten slag desulfurization device according to another embodiment of the present invention;

[0046] Figure 6 This is a schematic diagram of a system structure for resource utilization of laterite nickel ore leaching tailings according to another embodiment of the present invention;

[0047] Figure 7 is one of the structural schematic diagrams of a reduction device according to an embodiment of the present invention;

[0048] Figure 8 is a second structural schematic diagram of a reduction device according to an embodiment of the present invention;

[0049] Fig. 9 This is a schematic diagram of a system structure for resource utilization of laterite nickel ore leaching tailings according to another embodiment of the present invention;

[0050] Fig.10 This is a schematic diagram of a system structure for resource utilization of laterite nickel ore leaching tailings according to another embodiment of the present invention;

[0051] Fig.11 This is a schematic diagram of a system structure for resource utilization of laterite nickel ore leaching tailings according to another embodiment of the present invention;

[0052] Fig.12 This is a schematic diagram of a system structure for resource utilization of laterite nickel ore leaching tailings according to another embodiment of the present invention;

[0053] Fig.13 The present invention is a schematic diagram of a system structure for resource utilization of laterite nickel ore leaching tailings according to another embodiment of the present invention. DETAILED DESCRIPTION

[0054] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0055] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0056] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0057] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0059] In the first aspect of the present invention, the present invention provides a method for resource utilization of laterite nickel ore leaching tailings. According to an embodiment of the present invention, reference is made to Figure 1 , the method comprising:

[0060] S100: Mixing the laterite nickel ore leaching tailings with flux

[0061] In this step, the laterite nickel ore leaching tailings are mixed with a flux to obtain a mixed material. Specifically, the laterite nickel ore leaching tailings can be tailings (with a water content of 30wt%-45wt%) after filter pressing of a laterite nickel ore wet leaching system. Based on the laterite nickel ore leaching tailings dry basis, the calcium content in the laterite nickel ore leaching tailings is not more than 8wt%, the iron content is 25wt%-50wt%, and the sulfur content is 3wt%-10wt%. The flux contains CaO and MgO, which can be pure CaO and pure MgO, or various materials rich in CaO and MgO, such as limestone, dolomite, steel slag, and high-magnesium laterite. By mixing the laterite nickel ore leaching tailings with the flux, the internal structure and chemical composition of the subsequently obtained slag can be adjusted, the metallurgical properties of the slag can be improved, the temperature of reduction iron extraction can be reduced, and the reduction iron extraction can be carried out. In addition, the mixing ratio of the laterite nickel ore leaching tailings and the flux can be adjusted according to the ratio of CaO to SiO in the iron extraction slag obtained by reduction iron extraction. 2 The mass ratio is (0.9-1.2):1, and the content of MgO in the iron slag is 6wt%-10wt%.

[0062] According to an embodiment of the present invention, before the laterite nickel ore leaching tailings are mixed with the flux, the laterite nickel ore leaching tailings are pre-dried in advance, and the water content of the pre-dried laterite nickel ore leaching tailings is 15wt%-20wt%, and it neither raises dust nor sticks, which is conducive to subsequent batching and transportation. The pre-drying can be carried out using a drying kiln and a dust collecting device. The drying kiln can use a steam dryer for indirect heat exchange (steam temperature ≥120°C) or a rotary drying kiln for direct heat exchange. For example, when a steam dryer is used, the heat source can be the steam generated in the subsequent melting slag desulfurization step and the flue gas waste heat recovery process in the reduction iron extraction step, and the steam temperature is ≥120°C; when a rotary kiln is used, a downstream drying kiln is preferably used, the hot air temperature is ≤700°C, the tail gas temperature is 105°C-120°C, and the rotary kiln heat source can use coal powder, coal gas or high-temperature tail gas.

[0063] S200: Desulfurization of the mixed material by melting slag

[0064] In this step, the mixed material is melted and slag-formed to desulfurize, so as to obtain slag and SO 2Specifically, the ends of the first fuel spray gun and the mixture spray gun are extended below the slag, and the oxygen-enriched air and fuel enter below the slag through the first fuel spray gun for submerged combustion to provide heat for melting the mixture. The specific chemical reaction equation includes C a H b O c N d S e +O 2 →CO+H 2 O+N 2 +SO 2 ,CO+O 2 →CO 2 ↑, the mixed material enters the bottom of the slag through the mixed material spray gun, and decomposes at 1500℃-1550℃ under the action of combustion heat (CaCO 3 →CaO+CO 2 ↑), desulfurization (Al 2 (SO 4 ) 3 +CO→Al 2 O 3 +CO 2 ↑+SO 2 ↑, Fe 2 (SO 4 ) 3 +CO→Fe 2 O 3 +CO 2 ↑+SO 2 ↑, CaSO 4 +CO → CaO + CO 2 ↑+SO 2 ↑), melting and slag forming reaction (FeO+SiO 2 →2FeO·SiO 2 , Fe 2 O 3 +CaO→CaO·Fe 2 O 3 ), and obtain high-temperature slag of about 1500℃ and SO 2 flue gas. Therefore, using a weak reducing atmosphere for desulfurization and melting is conducive to the decomposition of gypsum, and solves the problems of narrow reducing agent ratio range in conventional reduction desulfurization (too much or too little reducing agent is not conducive to desulfurization), difficulty in adapting to the fluctuation of the composition of the tailings from laterite nickel ore leaching, and the problem of adhesion caused by excessively high reduction desulfurization temperature. Specifically, the first fuel spray gun can use fuels such as coal gas, coal powder, fuel oil, and natural gas. The combustion-supporting wind used can include oxygen-enriched air with an oxygen concentration of not less than 65 vol%, the excess air coefficient can be 0.95-0.98, and the slag type can be FeO-Fe 3 O4 -CaO-SiO 2 -MgO-Al 2 O 3 , has very good fluidity at the melting temperature of the mixed material.

[0065] According to an embodiment of the present invention, in order to improve the subsequent reduction efficiency, an appropriate amount of reducing agent may be added to the above-mentioned mixed material to perform preliminary reduction. The specific chemical reaction equation includes: Fe 2 O 3 +CO→Fe 3 O 4 +CO 2 ↑, Fe 3 O 4 +CO → FeO + CO 2 ↑.

[0066] According to an embodiment of the present invention, SO 2 The flue gas is blown into the secondary air for secondary combustion, 2 The CO in the flue gas is burned cleanly. Specifically, the SO 2 O in the smoke 2 The content of can be controlled between 2 vol% and 4 vol%. The inventors found that if O 2 If the content is too low, the secondary combustion will not be complete. 2 If the content is too high, the flue gas volume will increase and SO 2 Transformed into SO 3 The present invention reduces the SO content after secondary combustion by 2 O in the smoke 2 The content of in the above range can not only make the secondary combustion reaction complete, but also reduce the amount of flue gas and SO 2 Transformed into SO 3 proportion.

[0067] According to an embodiment of the present invention, the above-mentioned SO 2 The flue gas can first be cooled to below 1200℃ and generate steam by recovering waste heat in the flue gas waste heat boiler, and then cooled to about 200℃ by the flue gas heat exchanger to generate hot air of 700℃-800℃, and finally sent to the acid plant after dust collection treatment, thereby realizing the comprehensive utilization of sulfur element in the tailings of laterite nickel ore leaching. The steam generated by recovering waste heat in the flue gas waste heat boiler can be used to pre-dry the tailings after pressure filtration of the laterite nickel ore wet leaching system. The 700℃-800℃ hot air obtained after heat exchange in the flue gas heat exchanger can be used as a heat source for preheating the mixed material. The insufficient part can be supplemented by burning coal gas, coal powder, fuel oil or other fuels, thereby improving the thermal utilization rate of the entire process and reducing energy consumption.

[0068] According to an embodiment of the present invention, before the molten slag desulfurization, the mixture obtained by mixing the laterite nickel ore leaching tailings with the flux can be dried and crushed, thereby reducing the particle size of the mixture, increasing the relative area of ​​the mixture, and removing free water from the mixture. Part of the gypsum in the laterite nickel ore leaching tailings is also dehydrated to become hemihydrate gypsum and CaSO 4 (H 2 O→H 2 O↑, CaSO 4 ·2H 2 O→CaSO 4 0.5H 2 O+H 2 O↑120℃-150℃, CaSO 4 0.5H 2 O→CaSO 4 +H 2 O↑≥165℃), thereby improving the efficiency of subsequent molten slag desulfurization and reducing the energy consumption of chemical materials. At the same time, it can homogenize the mixed materials, which is beneficial to the reduction and iron extraction. Specifically, the water content of the laterite nickel ore leaching tailings after drying and crushing can be no more than 2wt%, the particle size can be no more than 2mm, the flux particle size can be no more than 2mm, and the heat source for drying and crushing can be coal gas, pulverized coal, fuel oil or other fuels. And the drying and crushing can use a crusher, a powder pneumatic lifting device and a dust collecting device. The crusher can use a ball mill, a vertical mill, a wind-sweeping mill and a hammer crusher and other equipment that takes into account both crushing and drying. The powder pneumatic lifting device can use an air lifting pump, and the dust collecting device can use a bag dust collector. The hot air temperature at the crusher inlet can be 600℃-800℃, the bag tail gas temperature can be 120℃-150℃, and the air-to-material ratio is ≥200Nm 3 / t (the specific amount is calculated based on the heat balance of the moisture content of the wet material and the hot air temperature), the air flow velocity of the powder pneumatic lifting device is 4-10m / s (if it is too low, the dry slag particle size is too fine and the smoke rate is too high during melting; if the velocity is too high, on the one hand, the dry slag particle size is too coarse and the pipeline grinding is large, on the other hand, the system resistance is large and the energy consumption is high), the material stays in the powder pneumatic lifting device for ≥2s, and the crusher heat source can be gas. When gas is insufficient, other fuels such as pulverized coal and fuel oil can also be used.

[0069] According to an embodiment of the present invention, before the mixed material is subjected to smelting slag desulfurization, the mixed material may be preheated in advance to complete rapid preheating and decomposition and to perform moderate temperature increase. The specific chemical reaction equation includes: 2 O→H 2 O↑, CaSO 4 ·2H 2 O→CaSO 4 +H 2O↑, CaSO 4 0.5H 2 O→CaSO 4 +H 2 O↑, Fe(OH) 3 →Fe 2 O 3 +H 2 O↑, Al(OH) 3 →Al 2 O 3 +H 2 O↑, Ca(OH) 2 →CaO+H 2 O↑, CaMgC 2 O 6 →CaCO 3 +MgO+H 2 O↑, thereby improving the efficiency of subsequent molten slag desulfurization and reducing the energy consumption of chemical materials.

[0070] Specifically, preheating can be performed using a 3-5 stage cyclone preheater and an electrostatic precipitator. The preheating method can be countercurrent heat exchange. The heat source for preheating can be the 700°C-800°C hot air generated in the waste heat recovery process of the subsequent slag-making and desulfurization steps. The insufficient part is supplemented by burning coal gas, coal powder, fuel oil and other fuels. The hot air temperature at the inlet of the cyclone preheater is 700°C-800°C. The temperature of the mixed material after preheating can be 500°C-650°C. The temperature of the tail gas after preheating is ≤200°C. The tail gas is discharged after dust removal by the electrostatic precipitator, and the collected smoke dust is returned to the cyclone preheater. The tail gas after dust removal can be used as a heat source for pre-drying to reduce the energy consumption of pre-drying. In addition, the inventors found that if the hot air temperature used for preheating is too high, it will cause some sulfates (the decomposition temperature of aluminum sulfate is 685°C) to decompose prematurely, which is not conducive to the subsequent SO 2 If the temperature of the hot air used for preheating is too low, the temperature of the mixed material will be too low, which is not conducive to improving the efficiency of subsequent molten slag desulfurization and reducing the energy consumption of the chemical material. The present invention controls the temperature of the hot air used for preheating within the above range, which can not only improve the efficiency of subsequent molten slag desulfurization and reduce the energy consumption of the chemical material, but also avoid premature decomposition of sulfate, thereby facilitating the subsequent SO 2 In addition, hot air can be used to preheat the mixed material to produce high-temperature tail gas, which can be used to pre-dry the tailings after filter pressing in the laterite nickel ore wet leaching system, making full use of waste heat and reducing energy consumption.

[0071] S300: Mix slag with reducing agent to reduce iron

[0072] In this step, the molten slag is mixed with the reducing agent to reduce and extract iron, so as to obtain molten iron, iron extracting slag and coal gas. Specifically, the end of the reducing agent spray gun and the end of the second fuel spray gun are extended below the slag layer, and the oxygen-enriched air and fuel enter the slag layer through the second fuel spray gun for submerged combustion to provide heat for reducing and extracting iron. The specific chemical reaction equation includes C a H b O c N d S e +O 2 →CO+H 2 O+N 2 +SO 2 ,CO+O 2 →CO 2 ↑, the reducing agent enters the lower part of the slag layer through the reducing agent spray gun, mixes with the slag and is reduced to iron at 1400℃-1500℃. Under the action of the reducing agent, the iron oxide in the slag is reduced to metallic iron, and molten iron, iron slag and coal gas are obtained. The specific chemical reaction equation includes: Fe 3 O 4 +CO → FeO + CO 2 ↑, FeO+C→Fe+CO↑, CaO+SiO 2 →2CaO·SiO 2 The molten iron will settle at the bottom of the furnace due to its relatively high density, thus being separated from the iron-extracting slag. The discharge temperature of the molten iron can be 1400℃-1500℃, and the discharge temperature of the iron-extracting slag can be 1450℃-1550℃. The iron content of the iron-extracting slag is ≤5%. The molten iron can be used for steelmaking, thereby realizing the comprehensive utilization of the iron element in the tailings of laterite nickel ore leaching. The iron-extracting slag can be used as a raw material for building materials after water crushing; and, since more heat is required for molten slag desulfurization and less heat is required for reduction and iron extraction, separating molten slag desulfurization from reduction and iron extraction can reduce energy consumption and reduce production and operation costs.

[0073] Specifically, the reduction and iron extraction can be carried out by using a reduction and iron extraction furnace, the reducing agent can be anthracite or crushed coke, the particle size can be 2mm-5mm, the fixed carbon content is ≥70%, and the reducing agent consumption per ton of molten iron is not less than 300kg. At the same time, during the reduction and iron extraction process, the carburizing agent can be sprayed into the molten iron layer to improve the carburizing efficiency. The carburizing agent can be anthracite or crushed coke, and the reduction and iron extraction can be CaO-SiO 2 -MgO-Al 2 O 3 Slag system, through the flux added during the preheating process, controls the CaO and SiO content in the iron slag 2The mass ratio of MgO to ZnO is (0.9-1.2):1, and the content of MgO in the iron slag is 6wt%-10wt%. The viscosity of the iron slag is less than 0.8Pa·s at 1450°C, and it has very good fluidity.

[0074] According to an embodiment of the present invention, the end of the second fuel spray gun can be located 200m below the upper surface of the slag layer and above the molten iron surface. The second fuel spray gun can use high calorific value fuels such as pulverized coal, natural gas, and fuel oil. The combustion-supporting air used can include oxygen-enriched air with an oxygen concentration of not less than 65vol%. The inventors have found that by controlling the excess air coefficient, the volume of CO in the reaction system can be 2.5 times that of CO and 1.5 times that of CO. 2 The total volume content is not less than 80%, which is beneficial to improve the reduction effect and reduce the iron content of the iron slag.

[0075] According to an embodiment of the present invention, during the reduction and iron extraction process, supplementary heat can be provided by a third fuel spray gun and / or an electrode. When supplementary heat is provided by the third fuel spray gun, the end of the third fuel spray gun is extended below the slag layer, and oxygen-enriched air and fuel enter the slag layer through the third fuel spray gun for submerged combustion to supplement heat for reduction and iron extraction; when supplementary heat is provided by the electrode, the end of the electrode is extended below the slag layer to supplement heat for reduction and iron extraction. Specifically, the third fuel spray gun can use high calorific value fuels such as pulverized coal, natural gas, and fuel oil, and the combustion-supporting wind used can include oxygen-enriched air with an oxygen concentration of not less than 65 vol%, and the inventors have found that by controlling the excess air coefficient so that the volume of CO in the reaction system accounts for 1:1 of the total volume of CO and CO 2 The total volume content is not less than 80%, which can improve the reduction effect and reduce the iron content of the iron slag.

[0076] According to an embodiment of the present invention, the coal gas obtained by reduction and iron extraction is collected through negative pressure, and clean coal gas can be obtained after waste heat recovery, cooling and dust removal. Most of the clean coal gas is used as fuel for slag melting and desulfurization, and the rest is used as a heat source for preheating and drying and crushing. The steam generated by waste heat recovery can be used to pre-dry the tailings after pressure filtration in the laterite nickel ore wet leaching system, thereby improving the utilization efficiency of the coal gas (compared with conventional coal gas power generation) and the thermal utilization rate of the entire process, thereby reducing energy consumption. In addition, the coal gas can be used for waste heat recovery, cooling and dust removal by a coal gas utilization device. The coal gas utilization device can adopt a coal gas waste heat boiler, a cooling dust collecting device, a pressurized fan, a coal gas storage tank and a torch. After the coal gas comes out of the reduction iron-raising furnace, it is cooled to about 850℃-1000℃ through the flue of the coal gas waste heat boiler, and then it is quenched to below 200℃ through the cooling dust collecting device. The quenched coal gas is pressurized by a fan and sent to the coal gas storage tank, which can be used as fuel for pre-drying, preheating, desulfurization and melting steps.

[0077] Thus, the method for resource utilization of laterite nickel ore leaching tailings of the present invention can solve the environmental hidden danger problem of laterite nickel ore leaching tailings, comprehensively utilize the valuable elements such as iron and sulfur therein, produce considerable economic benefits, less energy consumption, low production cost, simple process, easy to operate, suitable for large-scale production, and have high practical value. In addition, by pre-drying, drying crushing, preheating, melting slag desulfurization, and reduction iron extraction are carried out separately, making full use of the advantages of each stage, using the steam or tail gas of the preheating process generated by melting slag desulfurization and reduction iron extraction waste heat recovery to pre-dry, using the coal gas generated by reduction iron extraction to carry out drying crushing, preheating, melting slag desulfurization, and achieve high efficiency utilization of coal gas (compared to conventional coal gas power generation). It should be noted that the method can also be used for laterite nickel ore production of ferronickel, replacing rotary kiln ore furnace (RKEF) process.

[0078] In a second aspect of the present invention, the present invention provides a system for resource utilization of laterite nickel ore leaching tailings. Figure 2 The system includes: a mixing device 100, a molten slag desulfurization device 200 and a reduction device 300.

[0079] According to an embodiment of the present invention, referring to Figure 2 The mixing device 100 has a laterite nickel ore leaching tailings inlet 101, a flux inlet 102 and a mixed material outlet 103, and is suitable for mixing the laterite nickel ore leaching tailings with the flux to obtain a mixed material. Specifically, the laterite nickel ore leaching tailings has a water content of 15wt%-20wt%, which is neither dusty nor sticky, and is conducive to subsequent batching and transportation. Based on the laterite nickel ore leaching tailings dry basis, the calcium content in the laterite nickel ore leaching tailings is not more than 8wt%, the iron content is 25wt%-50wt%, and the sulfur content is 3wt%-10wt%. The flux contains CaO and MgO. When the system is working, the laterite nickel ore leaching tailings are fed into the mixing device 100 through the laterite nickel ore leaching tailings inlet 101, and at the same time, the flux is The flux inlet 102 is fed into the mixing device 100, and the laterite nickel ore leaching tailings and the flux are mixed in the mixing device 100 to obtain a mixed material, which is discharged from the mixed material outlet 103. The laterite nickel ore leaching tailings are mixed with the flux before smelting slag desulfurization, which can directly adjust the internal structure and chemical composition of the subsequently obtained slag, improve the metallurgical properties of the slag, reduce the temperature of iron reduction, and facilitate the reduction of iron. The ratio of the laterite nickel ore leaching tailings and the flux can be adjusted according to the ratio of CaO and SiO in the iron-extracting slag obtained by iron reduction. 2 The mass ratio is (0.9-1.2):1, and the content of MgO in the iron slag is 6wt%-10wt%.

[0080] According to an embodiment of the present invention, referring to Figure 3-4The smelting slag desulfurization device 200 has a mixed material inlet 201, a slag outlet 202 and a flue gas outlet 203. The mixed material inlet 201 is connected to the mixed material outlet 103 and is suitable for smelting the mixed material to desulfurize the mixed material so as to obtain slag and SO 2 Specifically, the molten slag desulfurization device 200 may include a molten slag desulfurization device body 204, a mixture material spray gun 205, a first fuel spray gun 206, a secondary air port 207 and a flue 208. The molten slag desulfurization device body 204 includes a furnace 2041 and a slag zone 2042 from top to bottom. The mixture material spray gun 205 is provided with a mixture material inlet 201. The ends of the mixture material spray gun 205 and the first fuel spray gun 206 both extend into the slag zone 2042. The secondary air port 207 is provided in the furnace 2041. The flue 208 is connected to the furnace 2041. The flue 208 is provided with a flue gas outlet 203. The slag outlet 202 is provided on the side wall of the slag zone 2042. The oxygen-enriched air and the fuel enter the bottom of the slag through the first fuel spray gun 206 for submerged combustion to provide heat for the melting of the mixture. The specific chemical reaction equation includes C a H b O c N d S e +O 2 →CO+H 2 O+N 2 +SO 2 ,CO+O 2 →CO 2 ↑, the mixed material enters below the slag through the mixed material spray gun 205, and decomposes at 1500℃-1550℃ under the action of the combustion heat (CaCO 3 →CaO+CO 2 ↑), desulfurization (Al 2 (SO 4 ) 3 +CO→Al 2 O 3 +CO 2 ↑+SO 2 ↑, Fe 2 (SO 4 ) 3 +CO→Fe 2 O 3 +CO 2 ↑+SO 2 ↑, CaSO 4 +CO → CaO + CO 2 ↑+SO 2 ↑), melting and slag forming reaction (FeO+SiO 2 →2FeO·SiO 2 , Fe 2O 3 +CaO→CaO·Fe 2 O 3 ), and obtain high-temperature slag of about 1500℃ and SO 2 Therefore, reduction can be carried out separately from desulfurization and melting, and desulfurization and melting can be carried out in a weak reducing atmosphere, which is conducive to the decomposition of gypsum, and solves the problems of narrow reducing agent ratio range (too much or too little reducing agent is not conducive to desulfurization) in conventional reduction desulfurization, difficulty in adapting to the fluctuation of the tailings composition of laterite nickel ore leaching, and the problem of adhesion caused by excessively high reduction desulfurization temperature. The obtained high-temperature slag is discharged through the slag outlet 202, containing SO 2 The flue gas enters the furnace 2041, and secondary air is blown into the furnace 2041 through the secondary air port 207 to make the SO 2 The flue gas is then discharged through the flue gas outlet 203 after secondary combustion, ensuring that the SO 2 O in the smoke 2 The content of SO is between 2vol% and 4vol%, which can make the 2 The CO in the flue gas is burned cleanly and the flue gas volume and SO are reduced. 2 Transformed into SO 3 proportion.

[0081] According to an embodiment of the present invention, the distance between the top of the slag zone 2042 and the bottom of the molten slag desulfurization device body 204 is not less than 800 mm, so as to avoid damaging the furnace bottom when the slag is stirred to improve the reaction efficiency. The distance between the end of the mixing material spray gun 205 and the top of the slag zone 2042 is not less than 200 mm, and the distance between the end of the first fuel spray gun 206 and the top of the slag zone 2042 is not less than 200 mm. The mixed material is pneumatically transported to the molten slag desulfurization device body through the mixing material spray gun 205. The oxygen-enriched air and fuel are injected into the slag zone 2042 below the top 200mm below the top 200mm below the top 200mm below the top 204 through the first fuel injection gun 206 for submerged combustion, providing heat for the melting of the mixed material to improve the melting efficiency. The first fuel injection gun 206 can use high calorific value fuels such as pulverized coal, natural gas, and fuel oil. The combustion-supporting air used can include oxygen-enriched air with an oxygen concentration of not less than 65vol%, the excess air coefficient can be 0.95-0.98, and the flux slag type can be FeO-Fe 3 O 4 -CaO-SiO 2 -MgO-Al 2 O 3 , has very good fluidity at the melting temperature of the mixed material.

[0082] According to an embodiment of the present invention, in order to improve the reduction efficiency, an appropriate amount of reducing agent may be added to the above-mentioned mixed material. The specific chemical reaction equation includes: Fe 2 O 3 +CO→Fe 3 O 4 +CO 2 ↑, Fe 3 O 4 +CO → FeO + CO 2 ↑.

[0083] According to an embodiment of the present invention, the main body 204 of the molten slag making and desulfurization device can be a molten pool smelting furnace, which can include a furnace bottom 2043, a furnace wall 2044 and a furnace top 2045. The furnace wall 2044 is arranged around the furnace bottom 2043, and the furnace top 2045 is covered on the furnace wall 2044. The furnace bottom 2043 can be an insulating structure, and the furnace wall 2044 can be a water jacket embedded refractory brick structure. The slag outlet 202 and the secondary air port 207 are both arranged on the furnace wall 2044. The slag outlet 202 can be a siphon port, and the end of the mixing material spray gun 205 and the end of the first fuel spray gun 206 can pass through the furnace wall 2044 and extend into the molten pool smelting furnace. When the slag is stirred, the mixing material spray gun 205 and the first fuel spray gun 206 can be lifted. At the same time, the use of a molten pool smelting furnace for oxygen-enriched molten pool smelting can utilize low-priced lignite, thereby reducing costs. It can be understood that, referring to Figure 5 The end of the mixing material spray gun 205 can also pass through the furnace top 2045 and extend into the molten pool smelting furnace.

[0084] According to an embodiment of the present invention, referring to Figure 6 The molten slag desulfurization device 200 further includes a connected flue gas waste heat recovery device 21 and an electrostatic precipitator (not shown). The flue gas waste heat recovery device 21 is connected to the flue gas outlet 203 on the flue 208. Specifically, the flue gas waste heat recovery device 21 may include a connected flue gas waste heat boiler (not shown) and a flue gas heat exchanger (not shown). The SO 2 The flue gas can first be recovered by the flue gas waste heat boiler and cooled to below 1200℃ to generate steam, then cooled to about 200℃ by the flue gas heat exchanger and generate hot air of 700℃-800℃, and finally sent to the acid plant after dust collection by the electric precipitator, thereby realizing the comprehensive utilization of sulfur element in the tailings of laterite nickel ore leaching. The steam generated by recovering the waste heat from the flue gas waste heat boiler can be used to pre-dry the tailings after pressure filtration of the laterite nickel ore wet leaching system. The 700℃-800℃ hot air obtained after heat exchange in the flue gas heat exchanger can be used as a heat source for preheating the mixed material. The insufficient part can be supplemented by burning coal gas, coal powder, fuel oil or other fuels, thereby improving the thermal utilization rate of the entire process and reducing energy consumption.

[0085] According to an embodiment of the present invention, referring to Figure 7-8 The reduction device 300 includes a slag inlet 301, a reducing agent inlet 302, a molten iron outlet 303, an iron-removing slag outlet 304 and a gas outlet 305. The slag inlet 301 is connected to the slag outlet 202 and is suitable for mixing the slag with the reducing agent to reduce and extract iron, so as to obtain molten iron, iron-removing slag and gas. Specifically, the reduction device 300 may include a reduction device body 306, a reducing agent spray gun 307, a second fuel spray gun 308, a carburizing agent spray gun 309 and a supplementary heat device 310. A reduction zone 3061, a carburizing zone 3062 and a settling zone 3063 are horizontally arranged along the inner edge of the reduction device body 306. A partition wall 3064 is arranged between the carburizing zone 3062 and the settling zone 3063. There is a distance between the bottom end of the partition wall 3064 and the bottom of the reduction device body 306. The slag inlet 301, the reducing agent spray gun 307 and the second fuel spray gun 308 are all arranged in the reduction zone 3061, and the ends of the reducing agent spray gun 307 and the second fuel spray gun 308 are both extended below the slag layer 3066 of the reduction zone 3061. The reducing agent spray gun 307 is provided with a reducing agent spray gun. The inlet 302 is provided, the carburizing agent spray gun 309 is provided in the carburizing zone 3062 and the end of the carburizing agent spray gun 309 extends below the slag layer 3066 of the carburizing zone 3062, the supplementary heat device 310 is provided in the carburizing zone 3062 and the settling zone 3063, the molten iron outlet 303 is provided in the molten iron layer 3065 of the settling zone 3063, the iron slag outlet 304 is provided in the slag layer 3066 of the settling zone 3063, the slag inlet 301 can be connected to the slag outlet 202 through a flow channel (not shown), and the high-temperature slag of about 1500°C is continuously added to the reduction zone 3061 of the reduction device body 306 through the flow channel, and the oxygen-enriched air and the fuel enter the slag layer 3066 of the reduction zone 3061 through the second fuel spray gun 308 for submerged combustion. The specific chemical reaction equation includes C a H b O c N d S e +O 2 →CO+H 2 O+N 2 +SO 2 ,CO+O 2 →CO 2 ↑, the reducing agent is sprayed into the slag layer 3066 below the reduction zone 3061 through the reducing agent spray gun 307, mixed with the high-temperature slag and reduced at 1400℃-1500℃ for iron extraction. Under the action of the reducing agent, the iron oxides in the slag are reduced to metallic iron, and molten iron, iron extraction slag and coal gas are obtained. The specific chemical reaction equation includes: Fe 3 O 4 +CO → FeO + CO 2 ↑, FeO+C→Fe+CO↑, CaO+SiO2 →2CaO·SiO 2 The obtained molten iron and iron slag flow to the carburizing zone 3062. The molten iron gradually settles to the bottom of the furnace due to its relatively high density, thereby separating from the iron slag to form a molten iron layer 3065 and a slag layer 3066. The airflow sprayed by the carburizing agent spray gun 309 can spray the carburizing agent into the molten iron layer 3065, thereby improving the carburizing efficiency. The molten iron and part of the iron slag in the carburizing zone 3062 can flow into the settling zone 3063 through the bottom of the partition wall 3064. The partition wall 3064 can reduce the fluctuation of the settling zone 3063, which is beneficial to improving the separation effect of the molten iron and the iron slag. During the iron extraction process, supplementary heat can be provided by the supplementary heat device 308, and the molten iron in the sedimentation area 3063 is discharged from the molten iron outlet 303 and can be used for steelmaking, thereby realizing the comprehensive utilization of the iron element in the laterite nickel ore leaching tailings, and the iron extraction slag is discharged from the iron extraction slag outlet 304, which can be used as a building material raw material after water crushing, and the obtained coal gas is discharged from the coal gas outlet 305; and, since more heat is required for molten slag desulfurization and less heat is required for reduction iron extraction, performing molten slag desulfurization and reduction iron extraction in different equipment can reduce energy consumption and reduce production and operation costs.

[0086] According to an embodiment of the present invention, the reduction and extraction of iron can be carried out by using CaO-SiO 2 -MgO-Al 2 O 3 Slag system, through the flux added during the preheating process, controls the CaO and SiO content in the iron slag 2 The mass ratio of MgO to MgO is (0.9-1.2):1, and the content of MgO in the iron slag is 6wt%-10wt%. The viscosity of the iron slag is less than 0.8Pa·s at 1450°C, and it has very good fluidity. Specifically, the residence time of the iron slag in the settling zone 3043 is ≥30min to reduce its iron content. The discharge temperature of the molten iron can be 1400°C-1500°C, and the discharge temperature of the iron slag can be 1450°C-1550°C.

[0087] According to an embodiment of the present invention, the reduction device body 306 may be a molten pool smelting furnace, the furnace bottom is an insulating structure, the furnace wall at the molten iron layer 3065 is a refractory structure, the slag layer 3066 and the furnace wall above the slag layer 3066 are a water jacket embedded refractory brick structure, and the partition wall 3064 may be a water-cooled wall. In addition, the reduction device body 306 may maintain a slight positive pressure, thereby preventing excessive air leakage from reducing the purity of the obtained coal gas.

[0088] According to an embodiment of the present invention, the distance between the end of the second fuel spray gun 308 and the top of the slag layer 3066 is not less than 200 mm, and the second fuel spray gun 308 is located above the molten iron layer. The second fuel spray gun can use high calorific value fuels such as pulverized coal, natural gas, and fuel oil. The combustion-supporting air used can include oxygen-enriched air with an oxygen concentration of not less than 65 vol%. The excess air coefficient is controlled so that the volume of CO in the reaction system accounts for 1:1 of the CO and CO 2 The content of the total volume is not less than 80%, which can improve the reduction effect and reduce the iron content of the iron slag. The reducing agent can be anthracite or crushed coke, the particle size can be 2mm-5mm, the fixed carbon content is ≥70%, and the amount of reducing agent used for producing each ton of molten iron is not less than 300kg. The carburizing agent can be anthracite or crushed coke.

[0089] According to an embodiment of the present invention, the supplementary heat device 310 may include a third fuel spray gun and / or an electrode. When supplementary heat is provided by the third fuel spray gun, the end of the third fuel spray gun is extended below the slag layer 3066, and oxygen-enriched air and fuel enter the slag layer 3066 through the third fuel spray gun for submerged combustion to provide supplementary heat for iron reduction. When supplementary heat is provided by the electrode, the end of the electrode is extended below the slag layer 3066 to provide supplementary heat for iron reduction. Specifically, the third fuel spray gun may use high calorific value fuels such as pulverized coal, natural gas, and fuel oil, and the combustion-supporting air used may include oxygen-enriched air with an oxygen concentration of not less than 65 vol%, and the inventors have found that by controlling the excess air coefficient so that the volume of CO in the reaction system accounts for 1:1 of the total volume of CO and CO 2 The total volume content is not less than 80%, which can improve the reduction effect and reduce the iron content of the iron slag.

[0090] According to an embodiment of the present invention, referring to Fig. 9 The system further includes a pre-drying treatment device 400 and a first dust collecting device (not shown). The pre-drying treatment device 400 has a laterite nickel ore leaching tailings inlet 401, a dried leaching tailings outlet 402 and a pre-drying tail gas outlet 403. The dried leaching tailings outlet 402 is connected to the laterite nickel ore leaching tailings inlet 101, and the pre-drying tail gas outlet 403 is connected to the first dust collecting device, and is suitable for pre-drying the laterite nickel ore leaching tailings before mixing the laterite nickel ore leaching tailings with the flux. Specifically, the tailings after pressure filtration of the laterite nickel ore wet leaching system have a water content of 30wt%-45wt%, and the tailings are sent to the pre-drying treatment device 400 through the laterite nickel ore leaching tailings inlet 401. Under the action of the heat source, part of the water in the tailings after pressure filtration of the laterite nickel ore wet leaching system can be removed to obtain laterite nickel ore leaching tailings with a water content of 15wt%-20wt%. The laterite nickel ore leaching tailings with a water content of 15wt%-20wt% are neither dusty nor sticky, which is conducive to subsequent batching and transportation. The tail gas generated in the pre-drying treatment enters the first dust collecting device through the pre-drying tail gas outlet 403 for dust removal and then is discharged.

[0091] According to an embodiment of the present invention, the pre-drying treatment device 400 can adopt a steam dryer or a rotary drying kiln. When a steam dryer is adopted, the pre-drying treatment device 400 can be connected to the flue gas waste heat recovery device 21, and the heat exchange method is indirect heat exchange. The heat source can be the steam generated in the waste heat recovery process of the flue gas obtained by the molten slag desulfurization device 200, and the temperature is ≥120°C. When a rotary kiln type drying kiln is adopted, direct heat exchange is performed, preferably a co-current drying kiln, the hot air temperature is ≤700°C, the exhaust gas temperature is 105°C-120°C, and the first dust collecting device can be a bag dust collector.

[0092] According to an embodiment of the present invention, referring to Fig.10 The above system also includes a drying and crushing device 500, which has an inlet 501 for materials to be processed and an outlet 502 for dried and crushed materials. The inlet 501 for materials to be processed is connected to the outlet 103 for mixed materials, and the outlet 502 for dried and crushed materials is connected to the inlet 201 for mixed materials. The system is suitable for drying and crushing the mixed materials before supplying them to the molten slag desulfurization device 200, and supplying the obtained dried and crushed mixed materials to the molten slag desulfurization device 200. Specifically, the drying and crushing device 500 may include a drying and crushing device body (not shown), a powder pneumatic lifting device (not shown) and a second dust collecting device (not shown) connected in sequence. The drying and crushing device body has an inlet 501 for materials to be processed, and the second dust collecting device has an outlet 502 for materials after drying and crushing. The mixed material enters the drying and crushing device body through the inlet 501 for materials to be processed, and is crushed under the action of mechanical force, and is quickly mixed and dried by hot air at the same time. The dried and crushed mixed material is sent to the second dust collecting device by the powder pneumatic lifting device to be collected, and the dried and crushed mixed material is obtained. The mixed material collected in the second dust collecting device is supplied to the molten slag desulfurization device 200 through the outlet 502 for materials after drying and crushing. In this way, the particle size of the mixed material can be reduced, the comparative area of ​​the mixed material can be increased, and the free water in the mixed material can be removed. Part of the gypsum in the tailings of laterite nickel ore leaching is also dehydrated to become hemihydrate gypsum and CaSO 4 (CaSO 4 ·2H 2 O→CaSO 4 0.5H 2 O+H 2 O↑, CaSO 4 0.5H 2 O→CaSO 4 +H 2 O↑), thereby improving the efficiency of subsequent molten slag desulfurization and reducing the energy consumption of chemical materials. At the same time, it can homogenize the mixed materials, which is beneficial to the reduction and iron extraction.

[0093] Specifically, the hot air temperature used in the drying and crushing device can be 600℃-800℃, the tail gas temperature of the second dust collecting device can be 120℃-150℃, and the air-to-material ratio is ≥200Nm 3 / t (the specific amount is calculated based on the heat balance of the water content of the mixed material and the hot air temperature). The air flow velocity of the powder pneumatic lifting device can be 4m / s-10m / s, so as to avoid the dry slag particles being too fine, resulting in too high a smoke rate during melting, or the dry slag particles being too coarse, resulting in large pipe wear, large system resistance, and high energy consumption. The material stays in the pneumatic lifting device for not less than 2s, and the water content of the mixed material after drying and crushing is not more than 2wt%, and the particle size is not more than 2mm.

[0094] It should be noted that those skilled in the art can select the specific types of the drying and crushing device body, the powder pneumatic lifting device and the second dust collecting device according to actual needs. For example, the drying and crushing device body can be a ball mill, a vertical mill, an air-sweeping mill or a hammer crusher, etc., which are equipment that takes into account both crushing and drying. The powder pneumatic lifting device can be an air lifting pump, and the second dust collecting device can be a bag dust collector.

[0095] According to an embodiment of the present invention, referring to Fig.11 The system further includes a preheating device 600 and a third dust collecting device 61. The preheating device 600 has a mixed material inlet 601, a preheated material outlet 602 and a preheated exhaust gas outlet 603. The mixed material inlet 601 is connected to the mixed material outlet 103, and the preheated material outlet 602 is connected to the mixed material inlet 201. The system is suitable for preheating the mixed material before supplying the mixed material to the molten slag desulfurization device 200, and supplying the obtained preheated mixed material to the molten slag desulfurization device 200; the third dust collecting device 61 has a preheated exhaust gas inlet 611, a dust collecting outlet 612 and a dust-collected exhaust gas outlet 613. The preheated exhaust gas inlet 611 is connected to the preheated exhaust gas outlet 603, the dust collecting outlet 612 is connected to the mixed material inlet 601, and the dust-collected exhaust gas outlet 613 is connected to the pre-drying treatment device 400. Specifically, the mixed material is sent to the preheating device 600 through the mixed material inlet 601 to complete rapid preheating and decomposition, and to increase the temperature appropriately to obtain the preheated mixed material and preheated tail gas. The specific chemical reaction equation includes: CaSO 4 ·2H 2 O→CaSO 4 +H 2 O↑, CaSO 4 0.5H 2 O→CaSO 4 +H 2 O↑, Fe(OH) 3 →Fe 2 O 3 +H 2O↑, Al(OH) 3 →Al 2 O 3 +H 2 O↑, Ca(OH) 2 →CaO+H 2 O↑, CaMgC 2 O 6 →CaCO 3 +MgO+H 2 O↑, the obtained preheated mixed material is supplied to the molten slag desulfurization device 200 through the preheated material outlet 602, thereby improving the efficiency of subsequent molten slag desulfurization and reducing the energy consumption of chemical materials, and the obtained preheated exhaust gas enters the third dust collecting device 61 through the preheated exhaust gas inlet 611 for dust removal to obtain dust-collected exhaust gas and smoke, and the obtained dust-collected exhaust gas is sent to the pre-drying treatment device 400 through the dust-collected exhaust gas outlet 613 as a heat source for pre-drying treatment, which can fully utilize the waste heat, thereby reducing energy consumption, and the obtained smoke is returned to the preheating device 600 from the dust collecting outlet 612, thereby improving the resource utilization rate of laterite nickel ore leaching tailings. According to a specific embodiment of the present invention, refer to Fig.12 The mixed material inlet 601 can be connected to the dried and crushed material outlet 502, thereby further preheating the dried and crushed mixed material, thereby improving the efficiency of subsequent molten slag desulfurization and reducing the energy consumption of chemical materials.

[0096] According to an embodiment of the present invention, the third dust collecting device 61 may be an electrostatic precipitator, the preheating device 600 may be a cyclone preheater, the preheating method may be countercurrent heat exchange, and the heat source may be SO-containing water obtained by molten slag desulfurization. 2 The flue gas generates hot air of 700℃-800℃ in the waste heat recovery process, and the obtained preheated tail gas temperature is ≤200℃, and the temperature of the preheated mixed material can be 500℃-650℃. It should be noted that those skilled in the art can select the number of cyclone preheaters according to actual needs, for example, 3-5 levels.

[0097] According to an embodiment of the present invention, referring to Fig.13The system further includes a coal gas utilization device 31, which is connected to the coal gas outlet 305, the pre-drying device 400, the pre-heating device 600 and the molten slag desulfurization device 200, and is suitable for collecting the coal gas generated in the reduction device and supplying it to at least one of the pre-drying device 400, the pre-heating device 600 and the molten slag desulfurization device 200 for use as fuel. Specifically, the coal gas utilization device 31 may include a coal gas waste heat boiler (not shown), a cooling dust collection device (not shown), a pressurized fan (not shown) and a coal gas storage tank (not shown) connected in sequence. The coal gas discharged from the coal gas outlet 305 is collected by negative pressure, cooled to about 850°C-1000°C by a coal gas waste heat boiler, and then quenched to below 200°C by a cooling dust collecting device to obtain clean coal gas. The quenched coal gas is pressurized by a fan and sent to a coal gas storage tank for use as fuel by the pre-drying treatment device 400, the preheating device 600 and the molten slag desulfurization device 200. The steam generated by the coal gas waste heat boiler can be used to pre-dry the tailings after pressure filtration of the laterite nickel ore wet leaching system, thereby improving the utilization efficiency of the coal gas (compared with conventional coal gas power generation) and the thermal utilization rate of the entire process, thereby reducing energy consumption.

[0098] It should be noted that the fly ash generated by the above system can also be mixed with laterite nickel ore leaching tailings and flux for smelting slag desulfurization and reduction iron extraction, thereby further improving the resource utilization rate of laterite nickel ore leaching tailings.

[0099] Thus, the system of resource utilization of laterite nickel ore leaching tailings of the present invention can solve the environmental hidden danger problem of laterite nickel ore leaching tailings, comprehensively utilize the valuable elements such as iron and sulfur therein, produce considerable economic benefits, less energy consumption, and low production cost. In addition, by pre-drying, drying and crushing, preheating, molten slag desulfurization, and reduction iron extraction are respectively carried out in different equipments, the advantages of each stage are fully utilized, and the steam or tail gas of the preheating process generated by the waste heat recovery of molten slag desulfurization and reduction iron extraction is pre-dried, and the coal gas generated by reduction iron extraction is dried and crushed, preheated, and molten slag desulfurization is carried out, realizing the high efficiency utilization of coal gas (compared to conventional coal gas power generation). It should be noted that the system can also be used for laterite nickel ore production of ferronickel, replacing the rotary kiln ore furnace (RKEF) process.

[0100] The present invention is described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0101] Example 1

[0102] The tailings after filter pressing of a 20t laterite nickel ore wet leaching system (wet basis water content 35wt%, dry basis components: Ca5.1wt%, Fe32.5wt%, S7.2wt%, Si6.0wt%, Al2.5wt%) are dried to a water content of 18% using a steam dryer to obtain 15.85t of laterite nickel ore leaching tailings, consuming 4.55t of saturated steam at 180°C. The laterite nickel ore leaching tailings are dust-free and non-sticky.

[0103] 200kg / h of laterite nickel ore leaching tailings, 5.1kg / h of limestone powder, 32.8kg / h of dolomite powder and 4.9kg / h of fly ash are added into the drying and crushing device, and 166Nm of hot air at 700℃ is introduced. 3 / h, drying time 2.5s, to obtain 208.3kg / h of dry tailings (i.e. the mixed material after drying and crushing) with a water content of 1.8%.

[0104] 208.3kg / h of dry tailings are added to the preheating device for preheating, and at the same time, 153.3Nm of heat exchange hot air at 750℃ generated by the molten slag desulfurization device is introduced. 3 / h, coal powder 6.6kg / h, combustion air 143.8Nm 3 / h. 194.6 kg / h of hot roasted sand (i.e. preheated mixed material) at 600°C was obtained.

[0105] Hot baked sand 194.6kg / h, oxygen-enriched air 36.8Nm 3 / h(including O 2 70vol%), gas 114.2Nm 3 / h is sprayed into the molten pool surface (i.e. the top of the slag zone) in the molten slag desulfurization device at a height of 200mm. The excess air coefficient is controlled to be 0.97, the melting temperature is 1500℃, and the molten pool depth (i.e. the distance between the top of the slag zone and the bottom of the molten slag desulfurization device body) is 900mm. The hot baked sand undergoes decomposition, desulfurization, melting and slagging reactions under the action of the combustion heat, and produces 143.6kg / h of high-temperature slag. The slag composition is (mass fraction): TFe 34.4%, CaO 16.3%, SiO 2 15.8%, Al 2 O 3 6.9%, MgO 5.2%, S 0.1%, the slag fluidity is very good. In addition, the secondary air 39.2Nm 3 / h, and obtain 1450℃ high temperature flue gas 178.6Nm 3 / h(including O 2 3.0 vol%, SO 24.1vol%), cooled to about 1150℃ by flue gas waste heat boiler, then cooled to about 180℃ by flue gas heat exchanger and sent to acid making system to obtain hot air of about 750℃ 153.3Nm 3 / h (used for preheating of dry tailings).

[0106] 143.6kg / h of high-temperature slag is added to the reduction zone of the reduction device through the flow channel. In addition, 16.2kg / h of anthracite is added through the reducing agent spray gun, and 38.2kg / h of bituminous coal and 54.4Nm of combustion air are blown into the second fuel spray gun. 3 / h(including O 2 70vol%), the high-temperature molten slag flowing into the reduction device reacts with the added reducing agent at 1400℃-1450℃, and the iron oxides therein are reduced to metallic iron and carburized. The slag and iron are separated in the sedimentation zone, the sedimentation time is ≥30min, the power consumption of the sedimentation zone is 11.2kW, the molten iron discharge temperature is about 1450℃, and the iron slag discharge temperature is about 1500℃. The fluidity of the molten iron and the iron slag is very good. 47.9kg / h of molten iron (grade 94.6%, containing 0.2% S, containing 4.0% C) and 86.9kg / h of iron slag (Fe content is 5.5wt%, CaO and SiO 2 The mass ratio is 1.0, the MgO content is 8.4wt%, and the Al 2 O 3 The content is 12.8wt%, and the viscosity is less than 0.8Pa·s at 1450°C).

[0107] The coal gas obtained from the reduction device is cooled to about 850°C by the coal gas waste heat boiler, and then quenched to about 180°C, and used for preheating after dust removal and pressurization. The coal gas obtained is 122.1Nm 3 / h(CO: 51.2 vol%, H 2 : 9.6 vol%).

[0108] The sulfur recovery rate of the laterite nickel ore leaching tailings treatment process is 97.8%, the comprehensive Fe recovery rate is 92.3%, and the coal consumption per ton of iron is 1.3kg / t (including 337kg / t of anthracite and 935kg / h of bituminous coal).

[0109] Example 2

[0110] The laterite nickel ore leaching tailings 200 kg / h and dolomite powder 39.5 kg / h after drying in Example 1 were added into the drying and crushing device, and 205.1 Nm of hot air at 600 ° C was introduced. 3 / h, drying time 2.5s, to obtain 210kg / h of dry tailings (i.e. the mixed material after drying and crushing) with a water content of 1.5%.

[0111] 210kg / h of dry tailings are added to the preheating device for preheating, and at the same time, 217.9Nm of 700℃ heat exchange hot air generated by the molten slag desulfurization device is introduced 3 / h, coal powder 3.3kg / h, combustion air 94.4Nm 3 / h. 195.6 kg / h of hot roasted sand (i.e. preheated mixed material) at 500°C was obtained.

[0112] Hot baked sand 195.6kg / h, oxygen-enriched air 56.8Nm 3 / h(including O 2 65vol%), bituminous coal 10kg / h, coal gas 112.4Nm 3 / h is sprayed into the molten pool surface (i.e. the top of the slag zone) in the molten slag desulfurization device at a height of 200mm. The excess air coefficient is controlled to be 0.95, the melting temperature is 1500℃, and the molten pool depth (i.e. the distance between the top of the slag zone and the bottom of the molten slag desulfurization device body) is 800mm. The hot baked sand undergoes decomposition, desulfurization, melting and slagging reactions under the action of the combustion heat, and produces 144.8kg / h of high-temperature slag. The slag composition is (mass fraction): TFe 34.2%, CaO 15.9%, SiO 2 15.8%, Al 2 O 3 7%, MgO6%, S 0.1%, the slag fluidity is very good. In addition, the secondary air 71.9Nm 3 / h, and obtain 1445℃ high temperature flue gas 236.2Nm 3 / h(including O 2 4.0 vol%, SO 2 3.1vol%), cooled to about 1150℃ by flue gas waste heat boiler, then cooled to about 180℃ by flue gas heat exchanger and sent to acid making system to obtain hot air of about 700℃ 217.9Nm 3 / h (used for preheating of dry tailings).

[0113] 144.8kg / h of high-temperature slag is added to the reduction zone of the reduction device through the flow channel, and 16.3kg / h of anthracite is added through the reducing agent spray gun, and 32.4kg / h of bituminous coal and 52.4Nm of combustion air are blown into the second fuel spray gun. 3 / h(including O 265vol%), the high-temperature molten slag flowing into the reduction device reacts with the added reducing agent at 1400℃-1450℃, and the iron oxides therein are reduced to metallic iron and carburized. The slag and iron are separated in the sedimentation zone, the sedimentation time is ≥30min, the power consumption of the sedimentation zone is 14.1kW, the molten iron discharge temperature is about 1480℃, and the iron slag discharge temperature is about 1550℃. The fluidity of the molten iron and the iron slag is very good. 47.6kg / h of molten iron (grade 94.2%, containing 0.1% S, containing 4.5% C) and 88.3kg / h of iron slag (Fe content is 6.0wt%, CaO and SiO 2 The mass ratio is 0.9, the MgO content is 9.8wt%, and the Al 2 O 3 The content is 12.7wt%, and the viscosity is less than 0.8Pa·s at 1450°C).

[0114] The coal gas obtained from the reduction device is cooled to about 850°C by the coal gas waste heat boiler, and then quenched to about 180°C. After dust removal and pressurization, it is used for preheating and immersion melting. The coal gas obtained is 112.4Nm 3 / h(CO: 47.2 vol%, H 2 :8.2 vol%).

[0115] The sulfur recovery rate of the laterite nickel ore leaching tailings treatment process is 98.1%, the comprehensive Fe recovery rate is 91.2%, and the coal consumption per ton of iron is 1.3t / t (including 343kg / t of anthracite and 959kg / h of bituminous coal).

[0116] Example 3

[0117] The dried laterite nickel ore leaching tailings 200 kg / h, limestone powder 22.5 kg / h, and dolomite powder 25.3 kg / h after Example 1 were added into the drying and crushing device, and 800 ° C hot air 141.1 Nm 3 / h, drying time 2.5s, to obtain 218kg / h of dry tailings (i.e. the mixed material after drying and crushing) with a water content of 1.95%.

[0118] 218kg / h of dry tailings are added to the preheating device for preheating, and at the same time, the 800℃ heat exchange hot air 102.6Nm generated by the molten slag desulfurization device is introduced 3 / h, gas 30.7Nm 3 / h, combustion air 149.8Nm 3 / h. 204.2 kg / h of hot roasted sand (i.e. preheated mixed material) at 650°C was obtained.

[0119] Hot baked sand 204.2kg / h, oxygen-enriched air 27.5Nm 3 / h(including O 280vol%), gas 86.7Nm 3 / h is sprayed into the molten pool surface (i.e. the top of the slag zone) in the molten slag desulfurization device at a height of 200mm below the surface. The excess air coefficient is controlled to be 0.98, the melting temperature is 1500℃, and the molten pool depth (i.e. the distance between the top of the slag zone and the bottom of the molten slag desulfurization device body) is 1000mm. The hot baked sand undergoes decomposition, desulfurization, melting and slagging reactions under the action of the combustion heat, and produces 149.4kg / h of high-temperature slag. The slag composition is (mass fraction): TFe 33.1%, CaO 19.8%, SiO 2 15.4%, Al 2 O 3 6.5%, MgO 3.9%, S 0.1%, slag fluidity is very good. In addition, secondary air 19.4Nm 3 / h, and obtain 1475℃ high temperature flue gas 129Nm 3 / h(including O 2 2.0 vol%, SO 2 5.6vol%), cooled to about 1150℃ by flue gas waste heat boiler, then cooled to about 180℃ by flue gas heat exchanger and sent to acid making system to obtain hot air of about 800℃ 102.6Nm 3 / h (used for preheating of dry tailings).

[0120] 149.4kg / h of high-temperature slag is added to the reduction zone of the reduction device through the flow channel, and 16.1kg / h of anthracite is added through the reducing agent spray gun, and 44.2kg / h of bituminous coal and 52.4Nm of combustion air are blown into the second fuel spray gun. 3 / h(including O 2 80vol%), the high-temperature molten slag flowing into the reduction device reacts with the added reducing agent at 1400℃-1450℃, and the iron oxides therein are reduced to metallic iron and carburized. The slag and iron are separated in the sedimentation zone, the sedimentation time is ≥30min, the power consumption of the sedimentation zone is 8.5kW, the molten iron discharge temperature is about 1410℃, and the iron slag discharge temperature is about 1450℃. The fluidity of the molten iron and the iron slag is very good. 48.1kg / h of molten iron (grade 94.9%, containing 0.2% S, containing 3.7% C) and 92.8kg / h of iron slag (Fe content is 5.0wt%, CaO and SiO 2 The mass ratio is 1.2, the MgO content is 6.3wt%, and the Al 2 O 3 The content is 11.9wt%, and the viscosity is less than 0.8Pa·s at 1450°C).

[0121] The coal gas obtained from the reduction device is cooled to about 850°C by the coal gas waste heat boiler, and then quenched to about 180°C. After dust removal and pressurization, it is used for preheating and immersion melting. The coal gas obtained is 128.2Nm 3 / h(CO: 56.7 vol%, H 2 : 11.3 vol%).

[0122] The sulfur recovery rate of the laterite nickel ore leaching tailings treatment process is 97.4%, the comprehensive Fe recovery rate is 92.9%, and the coal consumption per ton of iron is 1.3kg / t (including 335kg / t of anthracite and 920kg / h of bituminous coal).

[0123] It can be seen from Examples 1-3 that the method for resource utilization of laterite nickel ore leaching tailings of the present invention can solve the environmental protection potential problem of laterite nickel ore leaching tailings, comprehensively utilize valuable elements such as iron and sulfur therein, generate considerable economic benefits, and has low energy consumption, low production cost, simple process, easy operation, suitable for large-scale production, and high practical value.

[0124] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0125] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for resource utilization of laterite nickel ore leaching tailings, characterized in that: include: (1) mixing the laterite nickel ore leaching tailings with a flux to obtain a mixed material; (2) subjecting the mixed material to smelting, slagging and desulfurization to obtain molten slag and flue gas containing SO2; (3) mixing the slag with a reducing agent to reduce and extract iron, so as to obtain molten iron, iron-extracting slag and coal gas; Before mixing the laterite nickel ore leaching tailings with flux, pre-drying the laterite nickel ore leaching tailings; In step (1), the laterite nickel ore leaching tailings are mixed with the flux and then dried and crushed; Before subjecting the mixed material to smelting slag desulfurization, the mixed material is preheated; The temperature of the preheated mixed material is 500°C-650°C; In step (2), during the molten slag desulfurization process, the ends of the first fuel spray gun and the mixed material spray gun are extended below the slag; In step (2), the combustion-supporting air used by the first fuel spray gun includes oxygen-enriched air, the oxygen concentration of the oxygen-enriched air is not less than 65 vol%, and the air excess coefficient is 0.95-0.

98.

2. The method according to claim 1, characterized in that In step (1), the flux contains CaO and MgO.

3. The method according to claim 1, characterized in that In step (1), the mixing ratio of the laterite nickel ore leaching tailings and the flux is based on the mass ratio of CaO to SiO2 in the iron ore slag being (0.9-1.2):1, and the content of MgO in the iron ore slag being 6wt%-10wt%.

4. The method according to claim 1, characterized in that: In step (2), the temperature of the molten slag desulfurization is 1500°C-1550°C.

5. The method according to claim 1, characterized in that: In step (3), the temperature of the reduction and iron extraction is 1400°C-1500°C.

6. The method according to claim 1, characterized in that In step (3), during the iron reduction process, the tip of the second fuel lance is extended below the slag layer.

7. The method according to claim 1, characterized in that In step (3), supplementary heat is provided for the reduction and iron extraction through a third fuel injection gun and / or an electrode.

8. The method according to claim 1, characterized in that: In step (3), when the third fuel spray gun is used to provide supplementary heat for the reduction and iron extraction, the end of the third fuel spray gun is extended below the slag layer, and the volume of CO in the reaction system accounts for no less than 80% of the total volume of CO and CO2.

9. A system for implementing the method for resource utilization of laterite nickel ore leaching tailings according to any one of claims 1 to 8, characterized in that: include: A mixing device, the mixing device having a laterite nickel ore leaching tailings inlet, a flux inlet and a mixed material outlet, and being suitable for mixing the laterite nickel ore leaching tailings with the flux to obtain a mixed material; A smelting slag desulfurization device, the smelting slag desulfurization device having a mixed material inlet, a slag outlet and a flue gas outlet, the mixed material inlet is connected to the mixed material outlet, and is suitable for smelting slag desulfurization of the mixed material to obtain slag and flue gas containing SO2; A reduction device, the reduction device comprising a slag inlet, a reducing agent inlet, a molten iron outlet, an iron-removing slag outlet, and a coal gas outlet, the slag inlet being connected to the slag outlet and being suitable for mixing the slag with the reducing agent to reduce and extract iron, so as to obtain molten iron, iron-removing slag and coal gas; The pre-drying treatment device also includes a laterite nickel ore leaching tailings inlet and a dried leaching tailings outlet, the dried leaching tailings outlet is connected to the laterite nickel ore leaching tailings inlet, and is suitable for pre-drying the laterite nickel ore leaching tailings before mixing the laterite nickel ore leaching tailings with a flux; The system further comprises a drying and crushing device, wherein the drying and crushing device comprises an inlet for materials to be processed and an outlet for dried and crushed materials, wherein the inlet for materials to be processed is connected to the outlet for the mixed material, and the outlet for dried and crushed materials is connected to the inlet for the mixed material, and is suitable for drying and crushing the mixed material in advance before supplying the mixed material to the molten slag desulfurization device, and supplying the obtained dried and crushed mixed material to the molten slag desulfurization device; A preheating device, the preheating device having a mixed material inlet, a preheated material outlet and a preheated tail gas outlet, the mixed material inlet is connected to the mixed material outlet, the preheated material outlet is connected to the mixed material inlet, and is suitable for preheating the mixed material before supplying the mixed material to the molten slag desulfurization device, and supplying the obtained preheated mixed material to the molten slag desulfurization device; A dust collecting device, the dust collecting device having a preheating tail gas inlet, a dust collecting outlet and a tail gas outlet after dust collection, the preheating tail gas inlet is connected to the preheating tail gas outlet, the dust collecting outlet is connected to the mixed material inlet, and the tail gas outlet after dust collection is connected to the pre-drying treatment device; The molten slag desulfurization device comprises: A slag-making and desulfurization device body, wherein the slag-making and desulfurization device body includes a furnace and a slag zone from top to bottom; A mixing material spray gun, the end of which extends into the slag zone; a first fuel spray gun, a distal end of the first fuel spray gun extending into the slag zone; A secondary air inlet, the secondary air inlet being arranged in the furnace; a flue, the flue being in communication with the furnace; A slag outlet, the slag outlet being arranged on a side wall of the slag zone; The reduction device comprises: A reduction device body, wherein a reduction zone, a carburizing zone and a sedimentation zone are arranged horizontally along the inner edge of the reduction device body, a partition wall is arranged between the carburizing zone and the sedimentation zone, and a distance exists between the bottom end of the partition wall and the bottom of the reduction device body; a slag inlet, the slag inlet being arranged in the reduction zone; A reducing agent spray gun, wherein the reducing agent spray gun is arranged in the reducing area; a second fuel spray gun, the second fuel spray gun being arranged in the reduction zone and the end of the second fuel spray gun extending below the slag layer in the reduction zone; A carburizing agent spray gun, wherein the carburizing agent spray gun is arranged in the carburizing zone and the end of the carburizing agent spray gun extends below the slag layer in the carburizing zone; A supplementary heat device is provided in the carburizing zone and the settling zone.

10. The system according to claim 9, characterized in that The molten slag desulfurization device also includes a flue gas waste heat recovery device, and the flue gas waste heat recovery device is connected to the flue.

11. The system according to claim 9, characterized in that It also includes a coal gas utilization device, which is connected to the coal gas outlet, the pre-drying treatment device, the preheating device and the molten slag desulfurization device, and is suitable for collecting the coal gas generated in the reduction device and supplying it to at least one of the pre-drying treatment device, the preheating device and the molten slag desulfurization device for use as fuel.

12. The system according to claim 9, characterized in that The distance between the top of the slag zone and the bottom of the molten slag desulfurization device body is not less than 800 mm, the distance between the end of the mixing material spray gun and the top of the slag zone is not less than 200 mm, and the distance between the end of the first fuel spray gun and the top of the slag zone is not less than 200 mm.

13. The system according to claim 9, characterized in that The distance between the end of the second fuel spray gun and the top of the slag layer in the reduction zone is not less than 200 mm, and the end of the second fuel spray gun is located above the molten iron layer.

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