Composite powder preparation system for laterite-nickel ore oxygen-enriched side-blown smelting and blowing method

Abstract

The invention discloses a composite powder preparation system and injection method for laterite-nickel ore oxygen-enriched side-blown smelting, and the method comprises the following steps: S1, firstly preparing pulverized coal with the particle size of less than 74 microns, then mixing and contacting with sulfur with the particle size of 10 mm, and forming a plurality of effective contact points attached with micron-sized pulverized coal on the surface of the sulfur, thereby reducing the contact resistance and constructing a charge conduction path; therefore, surface static charges generated in the sulfur grinding process are led out in time, and static accumulation of sulfur is weakened. Meanwhile, in the process of the step 2, the particle size of the sulfur is ground to be smaller than 74 microns, and the particle size of the mixed powder meeting the requirements of the subsequent injection process is prepared. Therefore, the problems that in the closed pneumatic conveying process, sulfur fine powder is prone to particle adsorption and agglomeration, and materials are blocked in a pipeline are solved, and the safety accident that electric spark discharge is prone to occurring between cloth bags, and the sulfur powder is ignited is avoided. Through two-step grinding of the pulverized coal and the sulfur, the contact resistance is reduced through different particle size mixing, and a remarkable effect is brought by a process of constructing a charge conduction path.

Description

Technical Field

[0001] This invention relates to the technical field of pyrometallurgical industry for nickel, and particularly to a composite powder preparation system and injection method for oxygen-enriched side-blown smelting of laterite nickel ore. Background Technology

[0002] Sulfur plays an indispensable role in the modern nickel pyrometallurgical industry. As a key smelting medium, it combines with metals in molten minerals at high temperatures to form nickel matte (Ni3S2-FeS). The high-density nickel matte sinks under gravity and accumulates at the bottom of the molten pool, thus achieving the smelting and enrichment of nickel metal.

[0003] However, sulfur, as a hazardous chemical, is flammable and explosive, making it difficult to store and transport. In the smelting industry, the methods of transporting and charging sulfur into furnaces have undergone several iterations. In traditional processes, sulfur is directly added to the smelting furnace in the form of coarse granules. This method is inefficient, results in poor working conditions for workers, and leads to uneven distribution of sulfur in the furnace. A large amount of sulfur is directly extracted with the flue gas under the negative pressure inside the furnace, resulting in significant losses. Subsequent smelting processes involve pre-mixing and roasting sulfur-containing minerals (such as pyrite) with concentrates before adding them to the smelting furnace, which improves the working environment in front of the furnace. However, the sulfidation efficiency of the minerals is still low, and additional desulfurization equipment is required in the roasting area. Furthermore, impurities brought in by sulfur-containing minerals increase the smelting burden. Some factories utilize the low melting point of sulfur (115-119 ℃) to heat and melt it into a more fluid liquid state, which is then transported into the furnace through pipelines. However, in actual operation, temperature control is difficult. When the temperature inside the pipeline approaches 160 ℃, the crystal structure of the sulfur monomers changes, the viscosity increases dramatically, and the pipelines become frequently blocked. Moreover, high-temperature sulfur delivery causes severe corrosion of the pipelines, posing safety hazards.

[0004] Through long-term practice and process improvement, sulfur powder injection technology has been gradually applied in the smelting industry. Modern advanced nickel smelting processes such as flash furnaces and oxygen-enriched side-blown furnaces use a silo pump-type dense-phase injection method to add sulfur into the smelting furnace, achieving a revolutionary improvement in sulfur addition efficiency. This process relies on a sulfur lance connected to the smelting furnace body to inject fine sulfur powder into the furnace at a speed of 100-300 m / s, allowing the sulfur to directly act on the high-temperature melt while simultaneously achieving uniform agitation of the molten pool. During this process, the metal sulfidation reaction is complete, sulfur utilization is high, no impurity metals are introduced, and the closed-loop transportation ensures a clean workshop environment, representing a milestone innovation in the smelting industry.

[0005] The application of sulfur injection technology in the smelting industry has significantly improved the efficiency of sulfur charging into the furnace and the sulfur reaction rate. At the same time, the closed-loop transportation has also significantly improved the working environment in the workshop.

[0006] However, in practical applications, sulfur itself has a very high resistivity ( The sulfur powder has a strong tendency to accumulate static electricity. During closed pneumatic conveying, fine sulfur powder is prone to particle adsorption and agglomeration, which increases viscosity and causes frequent blockages in the pipeline. The outlet pipeline of the silo pump and the front spray gun of the side-blown furnace are the most severely affected areas, requiring frequent shutdowns for cleaning and affecting smelting production efficiency. At the same time, static electricity accumulation also causes a significant potential difference between adjacent filter bags in the dust collector. When the accumulated voltage exceeds the air breakdown threshold, electric spark discharge can easily occur between the filter bags, igniting the sulfur powder and causing safety accidents. In addition, the local high temperature of the system caused by friction during the grinding process also poses certain safety hazards.

[0007] Therefore, this patent aims to provide a novel technical method to reduce the static electricity accumulation of sulfur during closed conveying and dust collection, thereby reducing the safety risks of sulfur preparation and injection in the smelting industry, reducing the frequency of material blockage in production, and improving the efficiency of nickel oxygen-enriched side-blown smelting. Summary of the Invention

[0008] In order to overcome the shortcomings of the above-mentioned technologies, this invention provides a sulfur-pulverized coal composite powder preparation process for nickel oxygen-enriched side-blown smelting systems, which optimizes the sulfur powder preparation and injection process by utilizing micron-level pulverized coal doping technology.

[0009] The technical solution of the present invention: A system for preparing composite powder for oxygen-enriched side-blown smelting of laterite nickel ore, comprising a coal powder grinding equipment, a sulfur mixing and grinding equipment, and an oxygen-enriched side-blown smelting equipment. The coal powder grinding equipment includes a vertical coal mill, a first bag filter, and a first silo pump. The sulfur mixing and grinding equipment includes a coal powder silo, a sulfur silo, an impact mill, a second bag filter, and a second silo pump. Hot air is introduced into the vertical lower part of the vertical coal mill to grind coal into pulverized coal with a particle size of <74μm. The pulverized coal is carried out by the rising hot air and collected by the first bag dust collector before falling into the first silo pump. A pneumatic conveying pipeline is provided between the first silo pump and the pulverized coal silo. The coal powder silo and sulfur silo are each equipped with a silo weighing scale and a feed pipe connected to the impact mill. The silo weighing scale controls the mass ratio of pulverized coal and sulfur in the coal powder silo and sulfur silo to be fed into the impact mill at (0.7-1.5):1. The impact mill grinds mixed powder with a particle size of < 74 μm, which is collected by the rising airflow into the second bag dust collector and then falls into the second chamber pump. The oxygen-enriched side-blown smelting equipment includes a pre-furnace baghouse dust collector, a sulfur finished product storage silo, a fluidized bed silo, a silo-type injection silo, and an oxygen-enriched side-blown furnace. A pneumatic conveying pipeline is installed between the second silo-type pump and the pre-furnace baghouse dust collector. After the pre-furnace baghouse dust collector collects the finished product mixed powder, the finished product mixed powder falls into the pre-furnace sulfur finished product storage silo for storage, and then enters the fluidized bed silo where it is atomized by nitrogen gas and sent to the silo-type injection silo. Relying on nitrogen gas at a pressure of 6-7 bar, the powder is transported in a dense phase to the primary tuyeres of the oxygen-enriched side-blown furnace to participate in the smelting reaction.

[0010] A further feature of the present invention is that a nitrogen closed-loop gas path is provided between the impact mill, the second bag filter, and the second chamber pump, and all of them operate under a nitrogen atmosphere.

[0011] A further feature of the present invention is that the coal powder silo, sulfur silo, and sulfur finished product storage silo are all equipped with an oxygen content monitoring device, a nitrogen flow atomization device, and a nitrogen replenishment device. When the oxygen content monitoring device detects that the oxygen content has reached a preset threshold, the nitrogen flow atomization device and the nitrogen replenishment device are activated.

[0012] A further feature of the present invention is that the coal powder grinding equipment also includes a raw coal bunker and a quantitative coal feeder, which quantitatively feeds coal powder to the vertical coal mill.

[0013] A further feature of the present invention is that each bag of the second bag filter and the furnace front bag filter is grounded to prevent static electricity.

[0014] A further feature of the present invention is that the silo-type blown powder hopper is provided with 6 blown outlets and connected to 6 furnace front spray guns. The finished mixed powder is fed into the oxygen-enriched side-blown furnace from the blown powder hopper through the furnace front spray guns at a pressure of 6-7 bar.

[0015] A further feature of the present invention is that the coal powder grinding equipment, the sulfur mixing and grinding equipment, and the oxygen-enriched side-blown smelting equipment are respectively located in different workshops.

[0016] The technical solution of this invention: a method for preparing and injecting composite powder for oxygen-enriched side-blown smelting of laterite nickel ore, characterized by comprising the following steps: S1. Coal powder preparation: Select raw coal blocks with a particle size of 10 mm and quantitatively feed them into the vertical coal mill. While grinding the raw coal blocks, high-temperature hot air is introduced from the vertical bottom to dry the coal. The high-temperature hot air is used as an upward airflow to carry out the ground coal powder, which is then screened by a separator and collected and stored by the first bag dust collector. The particle size of the finished coal powder is controlled to be <74μm.

[0017] S2. Preparation of mixed powder: Coal powder with a particle size of <74μm is mixed with sulfur with a particle size of 10 mm at a mass ratio of (0.7 - 1.5):1 in an impact mill. The coal powder with a particle size of <74μm and the sulfur with a particle size of 10 mm are mixed and contacted, forming numerous micron-sized effective contact points of coal powder on the sulfur surface, reducing contact resistance and constructing charge conduction pathways, thereby timely discharging the surface static charge generated during the sulfur grinding process and weakening the static accumulation of sulfur. The impact mill utilizes the principle of high-speed centrifugation to allow the impacting components in the grinding chamber to mix, collide, rub, and crush the mixed powder, pulverizing the mixed powder to a particle size of < 74 μm. The pulverized powder is carried by the rising airflow to the classification zone. Powder with the required particle size enters the second bag dust collector with the rising airflow and is collected, while particles with an excessively large particle size continue to be returned to the grinding chamber for further pulverization. The impact mill and bag filter dust collector are both operated under a nitrogen atmosphere. The finished product airflow after grinding enters the second bag dust collector connected to the impact mill. The finished mixed powder is intercepted and collected by the bag, and the nitrogen gas returns to the impact mill through the return pipe, forming a closed loop. S3. Injection: The finished mixed powder enters the chamber pump through a pneumatic butterfly valve and is transported to the smelting workshop under a pressure of 6-7 bar using a dense nitrogen phase. After entering the smelting workshop, the finished mixed powder is collected by the bag dust collector at the top of the injection system, falls into the sulfur finished product storage silo in front of the furnace for storage, then enters the fluidized silo to be atomized by nitrogen flow, and is sent to the silo-type injection silo. Finally, relying on nitrogen at a pressure of 6-7 bar, it is transported in a dense phase to the primary tuyeres of the oxygen-enriched side-blown furnace to participate in the smelting reaction.

[0018] A further feature of the present invention is that in step S1, the coal powder is anthracite powder ground from anthracite coal, and the ignition point of the mixed powder is higher than that of sulfur due to the addition and mixing of the anthracite powder.

[0019] Using the above technical solution, in terms of raw material grinding, the volatile hydrocarbons contained in micron-sized pulverized coal can form a uniform oily coating layer on the surface of sulfur particles, improving the lubrication performance of the mixture; at the same time, the extremely fine coal powder particles can effectively construct charge conduction pathways, which can promptly remove the surface static charge generated during the sulfur grinding process, significantly weakening the static electricity accumulation effect. In terms of smelting injection, sulfur is used in conjunction with pulverized coal of 200 mesh (approximately 74 μm) or smaller. The large specific surface area of ​​the mixed flux allows for rapid reaction with the melt (main reactions: C + O2 → CO2, 2C + CO2 → 2CO), ensuring the release of enormous energy within a very short residence time and compensating for the heat loss during the endothermic reaction of sulfur gasification (2S → S2). Furthermore, the rapid combustion of fine coal effectively consumes oxygen, creating a low-oxygen potential environment that allows sulfur to react more effectively with precious metals (Ni, Co, etc.) dispersed in the slag, forming stable nickel matte. This effectively prevents the loss of sulfur dioxide (S2 + 2O2 → 2SO2) from direct contact between gaseous sulfur and oxygen. Therefore, leveraging these characteristics, this patent provides a safer and more efficient grinding and injection method for nickel metal smelting.

[0020] The beneficial effects of this invention are: a. Sulfur-pulverized coal mixed grinding, relying on the lubricating properties of the oily surface of pulverized coal, can effectively reduce the frequency of material blockage in equipment and pipelines, significantly improve conveying efficiency, keep equipment clean, and reduce the risk of spontaneous combustion of accumulated material; b. The ignition point of sulfur is between 230 and 260 ℃, while the ignition point of anthracite powder is above 450 ℃. The addition of pulverized coal increases the overall ignition point of the mixture, reducing the risk of combustion caused by local high temperature in the equipment. c. Sulfur is mostly pulverized using impact mills, whose pulverizing chambers are mainly composed of metal components. The collision between the metal components and the sulfur generates a large amount of static electricity, which cannot be released through a good conductor. A large amount of sulfur powder carrying static electricity is very likely to generate spark discharge. Micron-sized coal powder is an excellent conductor, and the charge is relatively easy to conduct. Its static electricity accumulation capacity is weak. The addition of coal powder can conduct away the accumulated charge on the surface of the raw material, greatly reducing the risk of static electricity explosion caused by accumulated charge. d. The flammability of sulfur itself makes its industrial drying difficult. By mixing it with pulverized coal, the moisture content of the mixture can be reduced, preventing the materials from sticking together and improving the combustion efficiency after entering the furnace, thus reducing the extra heat consumption of smelting. e. In the nickel smelting process, the sulfidation reaction of sulfur on the target metal needs to be carried out under high-temperature reducing conditions. Powdered coal provides a large amount of heat during combustion, while also providing an excellent reducing environment. The carbon in the powdered coal can reduce oxide minerals such as NiO, FeO, Fe2O3, and Fe3O4 to elemental metals, making them more likely to combine with sulfur monomers to form nickel matte, producing the target product. This improves sulfur utilization and significantly enhances overall smelting efficiency. f. Sulfur monomers have a strong corrosive effect on equipment. The reducing environment created by pulverized coal can inhibit the generation of oxidizing acidic gases such as SO2 and SO3, thus protecting equipment and pipelines and extending system life. g. Pulverized coal is an essential flux for nickel oxygen-enriched side-blown smelting. The use of sulfur-pulverized coal mixture in the injection process will not introduce impurities into the furnace.

[0021] h. Simply mixing coal powder and sulfur makes it difficult to construct a charge conduction pathway, especially when the particle sizes of the two are similar. Because both surfaces have microscopic protrusions and depressions, the actual contact area is only 0.1% to 1% of the macroscopic area. When current is squeezed through these small contact points, the resistance will increase significantly.

[0022] Therefore, in step S1, coal powder with a particle size <74μm is first prepared, and then mixed and contacted with sulfur with a particle size of 10 mm. By forming numerous effective contact points on the sulfur surface where micron-sized coal powder adheres, the contact resistance is reduced and a charge conduction pathway is constructed, thereby timely dissipating the surface static charge generated during the sulfur grinding process and weakening the static accumulation of sulfur. At the same time, in step 2, the sulfur particle size is also ground to <74μm, resulting in a mixed powder particle size that meets the requirements of the subsequent injection process.

[0023] This avoids the problem of sulfur powder particles adsorbing and agglomerating and the problem of material blockage in the pipeline during the closed pneumatic conveying process, and avoids the safety accident of electric spark discharge between the bags that could ignite the sulfur powder.

[0024] These are all significant effects brought about by the process of reducing contact resistance and building charge conduction pathways through two-step grinding of coal powder and sulfur and mixing of different particle sizes, which cannot be achieved by a simple process of mixing coal powder and sulfur with pre-ground particle size in one step. Attached Figure Description

[0025] Figure 1 The structure of this embodiment of the invention Figure 1 ; Among them, the raw coal bunker 1, vertical coal mill 2, first bag dust collector 3, first silo pump 4, pulverized coal silo 5, sulfur silo 6, impact mill 7, second bag dust collector 8, second silo pump 9, front bag dust collector 10, sulfur finished product storage silo 11, fluidized material silo 12, silo-type injection silo 13, and oxygen-enriched side-blown furnace 14.

[0026] To better illustrate this embodiment, some parts in the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the actual size of the product. Furthermore, the accompanying drawings are for illustrative purposes only and should not be construed as limiting this patent. Detailed Implementation

[0027] To make the technical solution and advantages of this application clearer, the technical solution of this application will be described in a clearer and more complete manner below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only some embodiments of this application, and are only used to explain this application, not to limit this application. It should be noted that, for ease of description, only the parts related to this application are shown in the accompanying drawings. Other related parts can be referred to the general design. In the absence of conflict, the embodiments and technical features in the embodiments of this application can be combined with each other to obtain new embodiments.

[0028] The invention will now be described in detail with reference to the accompanying drawings, such as... Figure 1 As shown, a composite powder preparation system for oxygen-enriched side-blown smelting of laterite nickel ore includes a coal powder grinding equipment, a sulfur mixing and grinding equipment, and an oxygen-enriched side-blown smelting equipment. The coal powder grinding equipment includes a vertical coal mill 2, a first bag filter 3, and a first silo pump 4. The sulfur mixing and grinding equipment includes a coal powder silo 5, a sulfur silo 6, an impact mill 7, a second bag filter 8, and a second silo pump 9. Hot air is introduced into the vertical lower part of the vertical coal mill 2 to grind coal into pulverized coal with a particle size of <74μm. The pulverized coal is carried out by the rising hot air and collected by the first bag dust collector 3 before falling into the first silo pump 4. A pneumatic conveying pipeline is provided between the first silo pump 4 and the pulverized coal silo 5. The coal powder silo 5 and sulfur silo 6 are each equipped with a silo weighing scale and a feed pipe connected to the impact mill 7. The silo weighing scale controls the mass ratio of pulverized coal and sulfur in the coal powder silo 5 and sulfur silo 6 to be fed into the impact mill 7 at (0.7 - 1.5):1. The impact mill 7 grinds mixed powder with a particle size of < 74 μm, which is collected by the rising airflow into the second bag dust collector and then falls into the second chamber pump. The oxygen-enriched side-blown smelting equipment includes a pre-furnace baghouse dust collector 10, a sulfur finished product storage silo 11, a fluidized bed silo 12, a silo-type injection silo 13, and an oxygen-enriched side-blown furnace 14. A pneumatic conveying pipeline is provided between the second silo-type pump and the pre-furnace baghouse dust collector 10. After the pre-furnace baghouse dust collector 10 intercepts and collects the finished product mixed powder, the finished product mixed powder falls into the pre-furnace sulfur finished product storage silo for storage, and then enters the fluidized bed silo 12 to be atomized by nitrogen flow and sent to the silo-type injection silo 13. Relying on nitrogen at a pressure of 6-7 bar, the powder is transported in a dense phase to the primary tuyeres of the oxygen-enriched side-blown furnace 14 to participate in the smelting reaction.

[0029] A nitrogen closed-loop gas path is provided between the impact mill 7 and the second bag dust collector 8, and both operate under a nitrogen atmosphere.

[0030] The coal powder silo 5, sulfur silo 6, and sulfur finished product storage silo 11 are all equipped with an oxygen content monitoring device, a nitrogen flow atomization device, and a nitrogen replenishment device. When the oxygen content monitoring device detects that the oxygen content has reached a preset threshold, the nitrogen flow atomization device and the nitrogen replenishment device are activated.

[0031] The coal powder grinding equipment also includes a raw coal bunker 1 and a quantitative coal feeder, which quantitatively feeds coal powder to the vertical coal mill 2.

[0032] Each bag in the second bag dust collector 8 and the furnace front bag dust collector 10 is grounded to prevent static electricity.

[0033] A further feature of the present invention is that the silo-type blown material silo 13 is provided with 6 blown outlets and connected to 6 furnace front spray guns. The finished mixed powder is fed from the blown material silo into the oxygen-enriched side-blown furnace 14 at a pressure of 6-7 bar through the furnace front spray guns.

[0034] A further feature of the present invention is that the coal powder grinding equipment, the sulfur mixing and grinding equipment, and the oxygen-enriched side-blown smelting equipment are respectively located in different workshops.

[0035] The technical solution of this invention: a method for preparing and injecting composite powder for oxygen-enriched side-blown smelting of laterite nickel ore, characterized by comprising the following steps: S1. Coal powder preparation: Select raw coal blocks with a particle size of 10 mm and quantitatively feed them into the vertical coal mill 2. While grinding the raw coal blocks, high-temperature hot air is introduced from the vertical bottom to dry the coal. The high-temperature hot air is used as an upward airflow to carry out the ground coal powder, which is then screened by a separator and collected and stored by the first bag dust collector 3. The particle size of the finished coal powder is controlled to be <74μm.

[0036] S2. Preparation of mixed powder: Coal powder with a particle size of <74μm is mixed with sulfur with a particle size of 10 mm at a mass ratio of (0.7 - 1.5):1 in an impact mill 7. The coal powder with a particle size of <74μm and the sulfur with a particle size of 10 mm are mixed and contacted, forming numerous micron-sized effective contact points of coal powder on the sulfur surface, reducing contact resistance and constructing charge conduction pathways, thereby timely discharging the surface static charge generated during the sulfur grinding process and weakening the static accumulation of sulfur. The impact mill 7 utilizes the principle of high-speed centrifugation to allow the impacting parts in the grinding chamber to mix, collide, rub, and crush the mixed powder, pulverizing the mixed powder to a particle size of < 74 μm. The pulverized powder is carried by the rising airflow to the classification zone. Powder with the required particle size enters the second bag dust collector with the rising airflow and is collected, while particles with excessively large particle sizes continue to return to the grinding chamber for further pulverization. The impact mill 7 and the bag filter dust collector are both operated under a nitrogen atmosphere. The finished product airflow after grinding enters the second bag dust collector connected to the impact mill 7. The finished mixed powder is intercepted and collected by the bag, and the nitrogen gas returns to the impact mill 7 through the return pipe, forming a closed loop. S3. Injection: The finished mixed powder enters the chamber pump through a pneumatic butterfly valve and is transported to the smelting workshop under a pressure of 6-7 bar using a dense nitrogen phase. After entering the smelting workshop, the finished mixed powder is collected by the bag dust collector at the top of the injection system, falls into the sulfur finished product storage silo in front of the furnace for storage, and then enters the fluidized silo 12 to be atomized by nitrogen flow. It is then sent to the silo-type injection silo 13, and finally transported to the primary tuyer of the oxygen-enriched side-blown furnace 14 under a pressure of 6-7 bar by nitrogen in a dense phase to participate in the smelting reaction.

[0037] A further feature of the present invention is that in step S1, the coal powder is anthracite powder ground from anthracite coal, and the ignition point of the mixed powder is higher than that of sulfur due to the addition and mixing of the anthracite powder.

[0038] Using the above technical solution, in terms of raw material grinding, the volatile hydrocarbons contained in micron-sized pulverized coal can form a uniform oily coating layer on the surface of sulfur particles, improving the lubrication performance of the mixture; at the same time, the extremely fine coal powder particles can effectively construct charge conduction pathways, which can promptly remove the surface static charge generated during the sulfur grinding process, significantly weakening the static electricity accumulation effect. In terms of smelting injection, sulfur is used in conjunction with pulverized coal of 200 mesh (approximately 74 μm) or smaller. The large specific surface area of ​​the mixed flux allows for rapid reaction with the melt (main reactions: C + O2 → CO2, 2C + CO2 → 2CO), ensuring the release of enormous energy within a very short residence time and compensating for the heat loss during the endothermic reaction of sulfur gasification (2S → S2). Furthermore, the rapid combustion of fine coal effectively consumes oxygen, creating a low-oxygen potential environment that allows sulfur to react more effectively with precious metals (Ni, Co, etc.) dispersed in the slag, forming stable nickel matte. This effectively prevents the loss of sulfur dioxide (S2 + 2O2 → 2SO2) from direct contact between gaseous sulfur and oxygen. Therefore, leveraging these characteristics, this patent provides a safer and more efficient grinding and injection method for nickel metal smelting.

[0039] The specific plan is as follows: Raw coal lumps with a particle size of approximately 10 mm are conveyed by a belt conveyor into the raw coal silo 1 of the pulverized coal workshop for storage. They are then metered and quantitatively fed into the vertical coal mill via a metering belt, falling onto the rotating grinding disc. Multiple installed grinding rollers crush the material. Simultaneously, high-temperature hot air is introduced from below to dry the coal. Qualified fine powder is carried upwards by the hot air and collected after being screened by a separator. Coarse powder falls back onto the grinding disc for regrinding, ultimately controlling the particle size of the finished pulverized coal to <74μm. The finished particles are collected by a bag filter connected to the rear of the vertical mill and then fall into a silo pump below, which then sends them through a pneumatic conveying pipeline to the pulverized coal storage silo in the sulfur workshop.

[0040] Inside the sulfur workshop, a coal-to-sulfur raw material silo with a volume ratio of 5:2 is set up. The two silo feed pipes are connected to two feed inlets on the side of the impact mill 7. Coal (raw material particle size < 74 μm) and sulfur (raw material particle size ≈ 10 mm) are fed into the impact mill 7 through the feed pipes, mixing in the mill at a mass ratio of (0.7 - 1.5):1. The impact mill utilizes the principle of high-speed centrifugation, allowing the impact components in the grinding chamber to mix, collide, rub, and crush the raw material particles, pulverizing coarse particles to a set particle size (finished product particle size < 74 μm) in a short time. The pulverized particles are carried by the rising airflow to the classification zone. Powder with the required particle size enters the dust collector with the rising airflow and is collected, while particles with excessively large sizes continue to be returned to the grinding chamber for further pulverization. The finished product airflow enters the bag filter dust collector behind the mill, where the solid finished product is trapped and collected by the filter bags. Nitrogen returns to the impact mill 7 through a return pipe, forming a closed loop. The solid finished material enters the silo pump through a pneumatic butterfly valve, and is then further processed at 6 - At a pressure of 7 bar, the nitrogen gas is transported to the smelting workshop in a dense phase. After entering the smelting workshop, the finished powder is collected by the bag dust collector at the top of the injection system, falls into the sulfur finished product storage silo in front of the furnace, and then enters the fluidized bed silo 12 to be atomized by nitrogen gas. It is then sent to the bin-type injection silo 13 and finally transported to the primary tuyeres of the oxygen-enriched side-blown furnace 14 in a dense phase at a pressure of 6-7 bar to participate in the smelting reaction.

[0041] The beneficial effects of this invention are: a. Sulfur-pulverized coal mixed grinding, relying on the lubricating properties of the oily surface of pulverized coal, can effectively reduce the frequency of material blockage in equipment and pipelines, significantly improve conveying efficiency, keep equipment clean, and reduce the risk of spontaneous combustion of accumulated material; b. The ignition point of sulfur is between 230 and 260 ℃, while the ignition point of anthracite powder is above 450 ℃. The addition of pulverized coal increases the overall ignition point of the mixture, reducing the risk of combustion caused by local high temperature in the equipment. c. Sulfur is mostly pulverized using impact mills, whose pulverizing chambers are mainly composed of metal components. The collision between the metal components and the sulfur generates a large amount of static electricity, which cannot be released through a good conductor. A large amount of sulfur powder carrying static electricity is very likely to generate spark discharge. Micron-sized coal powder is an excellent conductor, and the charge is relatively easy to conduct. Its static electricity accumulation capacity is weak. The addition of coal powder can conduct away the accumulated charge on the surface of the raw material, greatly reducing the risk of static electricity explosion caused by accumulated charge. d. The flammability of sulfur itself makes its industrial drying difficult. By mixing it with pulverized coal, the moisture content of the mixture can be reduced, preventing the materials from sticking together and improving the combustion efficiency after entering the furnace, thus reducing the extra heat consumption of smelting. e. In the nickel smelting process, the sulfidation reaction of sulfur on the target metal needs to be carried out under high-temperature reducing conditions. Powdered coal provides a large amount of heat during combustion, while also providing an excellent reducing environment. The carbon in the powdered coal can reduce oxide minerals such as NiO, FeO, Fe2O3, and Fe3O4 to elemental metals, making them more likely to combine with sulfur monomers to form nickel matte, producing the target product. This improves sulfur utilization and significantly enhances overall smelting efficiency. f. Sulfur monomers have a strong corrosive effect on equipment. The reducing environment created by pulverized coal can inhibit the generation of oxidizing acidic gases such as SO2 and SO3, thus protecting equipment and pipelines and extending system life. g. Pulverized coal is an essential flux for nickel oxygen-enriched side-blown smelting. The use of sulfur-pulverized coal mixture in the injection process will not introduce impurities into the furnace.

[0042] The design of this device and method eliminates the need for large equipment and water tanks, expanding transportation options. Water replacement and oxygenation are completed within the live animal bags 1, and the stacking of transport frames 2 prevents collisions and compression between the live animal bags 1, improving the utilization of transport space. The technical solution of this application has now been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent modifications or substitutions to the relevant technical features, and the technical solutions resulting from these modifications or substitutions will all fall within the scope of protection of this application.

Claims

1. A system for preparing composite powder for oxygen-enriched side-blown smelting of laterite nickel ore, characterized in that: The equipment includes a coal powder grinding equipment, a sulfur mixing and grinding equipment, and an oxygen-enriched side-blown smelting equipment. The coal powder grinding equipment includes a vertical coal mill, a first bag filter, and a first silo pump. The sulfur mixing and grinding equipment includes a coal powder silo, a sulfur silo, an impact mill, a second bag filter, and a second silo pump. Hot air is introduced into the vertical lower part of the vertical coal mill to grind coal into pulverized coal with a particle size of <74μm. The pulverized coal is carried out by the rising hot air and collected by the first bag dust collector before falling into the first silo pump. A pneumatic conveying pipeline is provided between the first silo pump and the pulverized coal silo. The coal powder silo and sulfur silo are each equipped with a silo weighing scale and a feed pipe connected to the impact mill. The silo weighing scale controls the mass ratio of pulverized coal and sulfur in the coal powder silo and sulfur silo into the impact mill to be (0.7 - 1.5):

1. The impact mill grinds mixed powder with a particle size of < 74 μm, which is collected by the rising airflow into the second bag dust collector and then falls into the second chamber pump. The oxygen-enriched side-blown smelting equipment includes a furnace-front baghouse dust collector, a sulfur finished product storage silo, a fluidized bed silo, a silo-type injection silo, and an oxygen-enriched side-blown furnace, which are connected in sequence by pipelines. A pneumatic conveying pipeline is provided between the second silo-type pump and the furnace-front baghouse dust collector. After the furnace-front baghouse dust collector intercepts and collects the finished product mixed powder, the finished product mixed powder falls into the furnace-front sulfur finished product storage silo for storage. Then, it enters the fluidized bed silo through the pipeline, is atomized by nitrogen gas, and is then fed into the silo-type injection silo. Relying on nitrogen gas at a pressure of 6-7 bar, it is transported in a dense phase to the primary tuyeres of the oxygen-enriched side-blown furnace to participate in the smelting reaction.

2. The system for preparing composite powder for oxygen-enriched side-blown smelting of laterite nickel ore according to claim 1, characterized in that: A nitrogen closed-loop gas path is provided between the impact mill, the second bag filter, and the second chamber pump, and all of them operate under a nitrogen atmosphere.

3. The system for preparing composite powder for oxygen-enriched side-blown smelting of laterite nickel ore according to claim 1, characterized in that: The coal powder silo, sulfur silo, and sulfur finished product storage silo are all equipped with an oxygen content monitoring device, a nitrogen flow atomization device, and a nitrogen replenishment device. When the oxygen content monitoring device detects that the oxygen content has reached a preset threshold, the nitrogen flow atomization device and the nitrogen replenishment device are activated.

4. The system for preparing composite powder for oxygen-enriched side-blown smelting of laterite nickel ore according to claim 1, characterized in that: The coal grinding equipment also includes a raw coal bunker and a quantitative coal feeder, which quantitatively feeds coal powder to the vertical coal mill.

5. The system for preparing composite powder for oxygen-enriched side-blown smelting of laterite nickel ore according to claim 1, characterized in that: Each bag in the second baghouse dust collector and the furnace front baghouse dust collector is grounded to prevent static electricity.

6. The system for preparing composite powder for oxygen-enriched side-blown smelting of laterite nickel ore according to claim 1, characterized in that: The silo-type blown powder hopper is equipped with 6 blown outlets and connected to 6 furnace front spray guns. The finished mixed powder is fed into the oxygen-enriched side-blown furnace from the blown powder hopper through the furnace front spray guns at a pressure of 6-7 bar.

7. A system for preparing composite powder for oxygen-enriched side-blown smelting of laterite nickel ore according to any one of claims 1-6, characterized in that: The coal powder grinding equipment, sulfur mixing and grinding equipment, and oxygen-enriched side-blown smelting equipment are respectively located in different workshops.

8. A method for preparing and injecting composite powder for oxygen-enriched side-blown smelting of laterite nickel ore, characterized in that: Includes the following steps, S1. Coal powder preparation: Select raw coal blocks with a particle size of 10 mm and quantitatively feed them into the vertical coal mill. While grinding the raw coal blocks, high-temperature hot air is introduced from the vertical bottom to dry the coal. The high-temperature hot air is used as an upward airflow to carry out the ground coal powder, which is then screened by a separator and collected and stored by the first bag dust collector. The particle size of the finished coal powder is controlled to be <74μm. S2. Preparation of mixed powder: Coal powder with a particle size of <74μm is mixed with sulfur with a particle size of 10 mm at a mass ratio of (0.7 - 1.5):1 in an impact mill. The coal powder with a particle size of <74μm and the sulfur with a particle size of 10 mm are mixed and contacted, forming numerous micron-sized effective contact points of coal powder on the sulfur surface, reducing contact resistance and constructing charge conduction pathways, thereby timely discharging the surface static charge generated during the sulfur grinding process and weakening the static accumulation of sulfur. The impact mill utilizes the principle of high-speed centrifugation to allow the impacting components in the grinding chamber to mix, collide, rub, and crush the mixed powder, pulverizing the mixed powder to a particle size of < 74 μm. The pulverized powder is carried by the rising airflow to the classification zone. Powder with the required particle size enters the second bag dust collector with the rising airflow and is collected, while particles with an excessively large particle size continue to be returned to the grinding chamber for further pulverization. The impact mill and bag filter dust collector are both operated under a nitrogen atmosphere. The finished product airflow after grinding enters the second bag dust collector connected to the impact mill. The finished mixed powder is intercepted and collected by the bag, and the nitrogen gas returns to the impact mill through the return pipe, forming a closed loop. S3. Injection: The finished mixed powder enters the chamber pump through a pneumatic butterfly valve and is transported to the smelting workshop under a pressure of 6-7 bar using a dense nitrogen phase. After entering the smelting workshop, the finished mixed powder is collected by the bag dust collector at the top of the injection system, falls into the sulfur finished product storage silo in front of the furnace for storage, then enters the fluidized silo to be atomized by nitrogen flow, and is sent to the silo-type injection silo. Finally, relying on nitrogen at a pressure of 6-7 bar, it is transported in a dense phase to the primary tuyeres of the oxygen-enriched side-blown furnace to participate in the smelting reaction.

9. The method for preparing and injecting composite powder for oxygen-enriched side-blown smelting of laterite nickel ore according to claim 8, characterized in that: In step S1, the coal powder is anthracite powder ground from anthracite coal. The ignition point of the mixed powder is higher than that of sulfur due to the addition and mixing of the anthracite powder.

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