Atomized iron powder and production method thereof

Abstract

The invention relates to the technical field of powder metallurgy and ironmaking, in particular to atomized iron powder and a production method thereof, and the atomized iron powder is obtained through the steps of ironmaking, atomization, magnetic separation, dehydration, drying, cooling and screening in sequence. In the step of iron making, at least one of sintered ore, pellet ore and lump ore is smelted into molten iron, the temperature of the molten iron is 1600-1750 DEG C, and the content of MFe in the molten iron is larger than or equal to 94.0% according to the mass percent; in the step of atomization, molten iron is atomized through high-pressure water to obtain a water-powder mixture, a circular seam-shaped nozzle is used for atomization, the water pressure is 10-20 MPa, and the water flow is 250-900 Nm < 3 > / h. According to the iron and steel industry molten iron price advantage and process advantage, the molten iron is directly atomized, the atomized iron powder is produced, the method is simple, the additive requirement for producing sulfate process titanium dioxide and Bayer process aluminum oxide can be met, and the production cost can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical fields of powder metallurgy and iron smelting, and particularly relates to an atomized iron powder and a production method thereof. Background Art

[0002] Metal iron powder plays a versatile role in chemical production. It has strong reducibility and can be used as a reducing agent in many redox reactions to promote the reaction in the desired direction. For example, iron powder is widely used in the production of titanium white by the sulfuric acid method. The addition of iron powder can greatly improve the reduction efficiency during titanium white production and reduce production costs. The performance requirements for iron powder used in the sulfuric acid method for titanium white are: MFe≥85%, Sn≤0.01%, Cr≤0.10%, Cu≤0.50%, H2O≤1.0%, and the iron powder is divided into three grades of 85, 88, and 90 according to the MFe content. The higher the grade, the more beneficial it is to the production of titanium white by the sulfuric acid method; during the production of alumina by the Bayer process, by adding metal iron powder, less or even no lime needs to be added, which can increase the iron element content in red mud (the tailings of alumina production by the Bayer process), so as to achieve the purpose of resource utilization of the originally difficult-to-use red mud. The requirements for metal iron powder used in the Bayer process for alumina are: MFe≥90%, metallization rate≥85%, and the mass ratio of -200 mesh size particles≥90%.

[0003] Depending on the production process, metallic iron powder mainly includes reduced iron powder and atomized iron powder. Comparatively speaking, atomized iron powder has higher purity and a higher selling price. There are two conventional production processes for reduced iron powder. One is to use a tunnel kiln and a reduction furnace to reduce iron concentrate powder and mill scale, and obtain primary reduced iron powder through magnetic separation and crushing. Then, through secondary reduction, crushing, and screening, secondary reduced iron powder is obtained. Both primary reduced iron powder and secondary reduced iron powder can meet the requirements of 90-quality iron powder for sulfuric acid process titanium dioxide and metallic iron powder for Bayer process alumina. However, this process has complex procedures, long production time, and high energy consumption, so the production cost is high and the product selling price is high. The other is to use secondary resources with high iron content such as steelmaking converter sludge. After reduction, the surface impurities and oxides are stripped from the metallic iron through ball milling, followed by magnetic separation and classification to obtain the product. Limited by the low purity of the raw materials, the product quality is low, which can meet the requirements of low-quality iron powder for sulfuric acid process titanium dioxide (with poor usage effect), but cannot meet the requirements of metallic iron powder for Bayer process alumina. Traditional atomized iron powder is obtained by melting high-purity scrap steel and cast iron in an electric furnace, followed by refining in a refining furnace, atomization, magnetic separation, drying, cooling, and screening to obtain atomized raw powder, and then reduction to obtain atomized iron powder. Both atomized raw powder and atomized iron powder can meet the requirements of 90-quality iron powder for sulfuric acid process titanium dioxide and metallic iron powder for Bayer process alumina. However, the raw materials used in this process are expensive, the procedures are complex, and the energy consumption is high. Therefore, its production cost is even higher than that of reduced iron powder, and the price is also more expensive. Moreover, traditional atomized iron powder is high-purity iron powder for powder metallurgy products. Whether atomized raw powder or atomized iron powder is used in the production of sulfuric acid process titanium dioxide, it is a case of over-quality. Considering cost, most enterprises producing sulfuric acid process titanium dioxide choose primary reduced iron powder as the reducing agent. Similarly, for cost reasons, Bayer process alumina enterprises also choose primary reduced iron powder as an additive.

[0004] In order to reduce the production cost while ensuring the product quality of sulfuric acid process titanium dioxide, Bayer process alumina, etc., developing atomized iron powder with a simple preparation method, low cost, and excellent quality has become an urgent problem to be solved in the current chemical industry. Summary of the Invention

[0005] In the iron and steel industry, hot metal is the common name for high-purity liquid iron obtained through physical and chemical reactions of various iron ores, fuels, and fluxes in a blast furnace. Its iron content is over 94% (mostly between 94% - 97%), and the temperature is above 1500°C. The price of hot metal is generally 200 - 300 yuan / ton lower than that of scrap steel. The cost of melting scrap steel into 1500°C molten steel in an electric furnace is 800 - 900 yuan / ton. Aiming at the technical problems of high cost and complex processes in the existing processes for preparing reduced iron powder and atomized iron powder, and high cost when applied to sulfuric acid process titanium dioxide and Bayer process alumina, the present invention provides a production method of low-cost atomized iron powder. Based on the price advantage of hot metal in the iron and steel industry, it is proposed to directly atomize the ordinary hot metal smelted from sinter, pellet, or / and lump ore to produce an atomized iron powder. The method is simple, which can not only meet the raw material requirements of sulfuric acid process titanium dioxide and Bayer process alumina, but also reduce the production cost.

[0006] The technical solution of the present invention is as follows: First, the present invention provides a production method of atomized iron powder, which obtains atomized iron powder through the steps of ironmaking, atomization, magnetic separation, dehydration, drying, cooling, and screening in sequence; among them, ironmaking is to smelt at least one of sinter, pellet, and lump ore into hot metal, the temperature of the hot metal is 1600 - 1750°C, and by mass percentage, the MFe content in the hot metal ≥ 94.0%; atomization is that the hot metal is atomized by high-pressure water to obtain a water-powder mixture. An annular slit nozzle is used for atomization, the water pressure is 10 - 20 MPa, and the water flow rate is 250 - 900 Nm 3 / h.

[0007] Further, ironmaking is to smelt sinter, pellet, lump ore, and coke in a blast furnace into hot metal.

[0008] Further, magnetic separation is to preliminarily separate the water-powder mixture with a wet magnetic separator to obtain wet iron powder with a water content of 25% - 30%.

[0009] Further, dehydration is to dehydrate the wet iron powder obtained by magnetic separation with a filter press to obtain wet iron powder with a water content of 10% - 15%.

[0010] Further, drying is to dry the wet iron powder with a water content of 10% - 15% obtained after dehydration to obtain atomized raw powder; the water content of the atomized raw powder ≤ 1.0%, and the dried atomized raw powder ≤ 100°C.

[0011] Further, a drum dryer is used as the drying equipment; the heat source of the drum dryer is the low-temperature waste gas with a temperature range of 150°C - 250°C generated by a sintering ring cooler.

[0012] The low-temperature waste gas generated by the sintering ring cooler of the steel mill is used as the drying heat source, realizing the efficient utilization of the low-temperature waste gas and reducing the drying cost.

[0013] Further, screening is to screen the atomized raw powder obtained by drying. The material passing through the sieve is the atomized iron powder.

[0014] Further, it includes the following steps: (1) Ironmaking: After proportioning sinter, pellet, lump ore and coke, they are put into the blast furnace for reaction to generate molten iron and slag. The molten iron and slag are separated, and the molten iron flows into the molten iron ladle. By mass percentage, MFe in the molten iron ≥ 95.5%, and the temperature of the molten iron in the molten iron ladle is 1600 - 1750 °C; (2) Atomization: The molten iron flows into the atomization device and is atomized by high-pressure water to obtain a water-powder mixture; The high-pressure water atomization uses an annular slit nozzle, the water pressure is 10 - 15 MPa, and the water flow rate is 250 - 500 Nm 3 / h; (3) Magnetic separation: The water-powder mixture is preliminarily separated by a wet magnetic separator to obtain wet iron powder with a water content of 25% - 30%; (4) Dewatering: The wet iron powder obtained by magnetic separation is dewatered by a filter press to obtain wet iron powder with a water content of 10% - 15%; (5) Drying: The wet iron powder obtained by dewatering is dried by a drum dryer to make its water content ≤ 1.0% to obtain atomized raw powder with a temperature ≤ 100 °C; The heat source of the drum dryer adopts the low-temperature waste gas generated by the sintering ring cooler with a temperature range of 150 °C - 250 °C; (6) Screening: The dried atomized raw powder is screened with a 40-mesh sieve, and the material passing through the sieve is the atomized iron powder; In the atomized iron powder, MFe ≥ 90%, Sn ≤ 0.01%, Cr ≤ 0.10%, Cu ≤ 0.50%, H2O ≤ 1.0%, which is used as the atomized iron powder for sulfuric acid process titanium dioxide.

[0015] Further, it includes the following steps: (1) Ironmaking: After proportioning sinter, pellet, lump ore and coke, they are put into the blast furnace for reaction to generate molten iron and slag. The molten iron and slag are separated, and the molten iron flows into the molten iron ladle. By mass percentage, MFe in the molten iron ≥ 94.0%, and the temperature of the molten iron in the molten iron ladle is 1600 - 1750 °C; (2) Atomization: The molten iron flows into the atomization device and is atomized by high-pressure water to obtain a water-powder mixture; The high-pressure water atomization uses an annular slit nozzle, the water pressure is 13 - 20 MPa, and the water flow rate is 400 - 900 Nm 3 / h; (3) Magnetic separation: The water-powder mixture is preliminarily separated by a wet magnetic separator to obtain wet iron powder with a water content of 25% - 30%; (4) Dehydration: The wet iron powder obtained by magnetic separation is dehydrated by a filter press to obtain wet iron powder with a water content of 10%-15%. (5) Drying: The wet iron powder obtained by dehydration is dried by a drum dryer to reduce its water content to ≤1.0% and obtain atomized raw powder with a temperature ≤100°C. The heat source of the drum dryer is the low-temperature waste gas with a temperature range of 150°C - 250°C generated by a sintering ring cooler. (6) Screening: The dried atomized raw powder is screened with a 200-mesh sieve, and the material passing through the sieve is atomized iron powder. In the atomized iron powder, the mass ratio of MFe ≥ 90.0%, the metallization rate ≥ 85.0%, and the mass ratio of the -200 mesh size fraction ≥ 90%. It is used as atomized iron powder for Bayer process alumina.

[0016] In the second aspect, the present invention provides an atomized iron powder prepared by the above production method.

[0017] The beneficial effects of the present invention are as follows: Aiming at the problems of complex processes and high costs in the preparation of reduced iron powder and atomized iron powder in the existing production methods, the present invention creatively proposes a production method of atomized iron powder through a series of processes such as atomization of ordinary molten iron smelted from sinter, pellet, or / and lump ore, combining the price advantage of molten iron in the iron and steel industry. The prepared atomized iron powder can be used in the production of sulfuric acid process titanium dioxide and Bayer process alumina, as atomized iron powder for sulfuric acid process titanium dioxide and atomized iron powder for Bayer process alumina, with low cost and meeting the production requirements. On the one hand, the raw material cost is reduced: directly using ordinary molten iron (iron content 94%-97%, temperature ≥1500°C) smelted in blast furnaces in the iron and steel industry as raw materials, compared with the production method of melting scrap steel (the cost of melting scrap steel is 800 - 900 yuan / ton), taking full advantage of the price advantage of molten iron which is 200 - 300 yuan / ton lower than that of scrap steel, significantly reducing the raw material cost. On the other hand, the production process is simplified and energy is saved and efficiency is increased across industries: the molten iron obtained by smelting is directly atomized, eliminating the processes of remelting and refining scrap steel or iron blocks in the traditional method, reducing energy consumption and equipment investment, and solving the problems of complex processes and high costs in the existing preparation process of atomized iron powder. The present invention provides a low-cost and high-quality production method of atomized iron powder for the sulfuric acid process titanium dioxide and Bayer process alumina fields, with significant industrial application value. Specific Embodiments

[0018] To enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0019] In the following embodiments, the ratio range of sintered ore: pellet ore: lump ore is 70%-80%: 10%-20%: 10%-20%, and coke is added according to the specific situation of blast furnace ironmaking.

[0020] Example 1 A production method of atomized iron powder includes the steps of ironmaking, atomization, magnetic separation, dehydration, drying, cooling, and screening. The specific operation steps are as follows: (1) Ironmaking: Charge sintered ore, pellet ore, lump ore, and coke according to the conventional ratio in ironmaking in the steel industry, and then input them into the furnace from the top of the blast furnace. After a series of physical and chemical reactions, molten iron and slag are generated and discharged from the taphole at the bottom of the blast furnace and flow into the main trough. After the molten iron and slag are separated, the molten iron flows into the molten iron ladle through the iron trough, and the slag flows into the slag treatment line through the slag trough. The chemical composition of the molten iron in the molten iron ladle is MFe 95.5%, Sn 0.009%, Cr 0.09%, Cu 0.02%, and the balance is C and some inevitable impurities. The temperature of the molten iron in the molten iron ladle is 1600°C; (2) Atomization: The molten iron flows from the taphole at the bottom of the molten iron ladle to the tundish, and then flows into the iron inlet of the atomization device from the taphole at the bottom of the tundish, and a water-powder mixture is obtained through high-pressure water atomization; High-pressure water atomization uses an annular slit nozzle, the water pressure is 10 MPa, and the water flow rate is 250 Nm 3 / h; (3) Magnetic separation: Use a wet magnetic separator to preliminarily separate the water-powder mixture to obtain wet iron powder with a water content of 30%; (4) Dehydration: Use a filter press to dehydrate the wet iron powder with a water content of 30% to obtain wet iron powder with a water content of 15%; (5) Drying: Use a drum dryer to dry the wet iron powder with a water content of 15% and reduce its water content to 1.00% to obtain atomized raw powder with a temperature of 100°C; The heat source of the drum dryer uses low-temperature waste gas generated by the sintering ring cooler in the steel plant with a temperature range of 150°C - 250°C; (6) Screening: Screen the atomized raw powder with a temperature of 100°C with a 40-mesh sieve, and the material passing through the sieve is the atomized iron powder.

[0021] The atomized iron powder prepared by using this production method can be used as the raw material for titanium white production by the sulfuric acid method, and its quality meets the requirements of atomized iron powder for titanium white by the sulfuric acid method. Its specific chemical component content is: MFe 90.9%, Sn 0.01%, Cr 0.09%, Cu 0.03%, H2O 1.00%. The mass ratio of the atomized iron powder passing through the 40-mesh sieve (-40 mesh powder yield) is 98.8%, and the utilization rate is high.

[0022] The cost of scrap steel is generally 200 yuan / ton - 300 yuan / ton higher than that of hot metal, and the production cost of melting scrap steel in an electric furnace and heating it up to 1600°C, which is the same as that of hot metal, is about 800 yuan / ton - 1000 yuan / ton. The -40 mesh powder yield (the ratio of the undersize powder passing through the 40-mesh sieve to the total atomized raw powder) is calculated at 98.8%. The cost of the atomized iron powder for titanium white by the sulfuric acid method with low cost obtained by the production method provided by the present invention is 1012 yuan / ton - 1315 yuan / ton lower than that obtained by the traditional production method of the same quality, and 500 yuan / ton - 800 yuan / ton lower than the production cost of the traditional reduced iron powder of the same quality. Using the production method provided by the present invention saves the energy consumption of melting scrap steel and iron blocks. Using the low-temperature waste gas of the steel plant as the drying heat source realizes the efficient utilization of the low-temperature waste gas and reduces the drying cost. It is a production method with low cost, high quality, higher scale, energy saving, and circular economy.

[0023] Example 2 A production method of atomized iron powder includes the steps of ironmaking, atomization, magnetic separation, dehydration, drying, cooling, and screening. The specific operation steps are as follows: (1) Ironmaking: Charge sinter, pellet, lump ore, and coke in the conventional proportion for ironmaking in the iron and steel field, and then put them into the furnace from the top of the blast furnace. After a series of physical and chemical reactions, hot metal and slag are generated and discharged from the taphole at the bottom of the blast furnace and flow into the main trough. After the hot metal and slag are separated, the hot metal flows into the hot metal ladle through the iron trough, and the slag flows into the slag treatment line through the slag trough. The chemical composition of the hot metal in the hot metal ladle is MFe 95.4%, Sn 0.008%, Cr 0.06%, Cu 0.02%, and the balance is C and some inevitable impurities. The temperature of the hot metal in the hot metal ladle is 1680°C; (2) Atomization: The hot metal flows from the taphole at the bottom of the hot metal ladle to the tundish, and then flows into the iron inlet of the atomization device from the taphole at the bottom of the tundish, and a water-powder mixture is obtained through high-pressure water atomization; High-pressure water atomization uses an annular slit nozzle, the water pressure is 13 MPa, and the water flow rate is 350 Nm 3 / h; (3) Magnetic separation: Use a wet magnetic separator to preliminarily separate the water-powder mixture to obtain wet iron powder with a water content of 28%; (4) Dehydration: Use a filter press to dehydrate the wet iron powder with a water content of 28% to obtain wet iron powder with a water content of 13%; (5) Drying: Use a drum dryer to dry the wet iron powder with a water content of 13% and reduce its water content to 0.76% to obtain atomized raw powder at a temperature of 86°C. The heat source of the drum dryer uses low-temperature waste gas with a temperature range of 150°C - 250°C generated by the sintering ring cooler of the steel plant. (6) Screening: Screen the atomized raw powder at a temperature of 86°C with a 40-mesh sieve, and the material passing through the sieve is the atomized iron powder.

[0024] The atomized iron powder prepared by using this production method can be used as the raw material for sulfuric acid process titanium dioxide production, and its quality meets the requirements of atomized iron powder for sulfuric acid process titanium dioxide. Its specific chemical component content is: MFe 90.6%, Sn 0.009%, Cr 0.06%, Cu 0.02%, H2O 0.76%. The mass ratio of the atomized iron powder passing through the 40-mesh particle size screening (-40-mesh powder yield) is 98.5%, and the utilization rate is high.

[0025] The cost of scrap steel is generally 200 yuan / ton - 300 yuan / ton higher than that of hot metal, and the production cost of melting scrap steel in an electric furnace and heating it up to 1680°C, which is the same as that of hot metal, is about 860 yuan / ton - 1100 yuan / ton. Calculated based on the -40-mesh powder yield (the ratio of the powder passing through the 40-mesh sieve to the total atomized raw powder) of 98.5%, the cost of the atomized iron powder obtained by the production method provided by the present invention is 1076 yuan / ton - 1421 yuan / ton lower than that obtained by the traditional production method of the same quality, and 500 yuan / ton - 900 yuan / ton lower than the production cost of traditional reduced iron powder of the same quality. Using the production method provided by the present invention saves the energy consumption of melting scrap steel and iron blocks. Using the low-temperature waste gas of the steel plant as the drying heat source realizes the efficient utilization of low-temperature waste gas and reduces the drying cost. It is a production method with low cost, high quality, higher scale, energy saving, and circular economy.

[0026] Example 3 A production method of atomized iron powder, including the steps of ironmaking, atomization, magnetic separation, dehydration, drying, cooling, and screening. The specific operation steps are as follows: (1) Ironmaking: Charge sinter, pellet, lump ore, and coke in the conventional proportion for ironmaking in the steel industry, and then feed them into the furnace from the top of the blast furnace. After a series of physical and chemical reactions, hot metal and slag are generated and discharged from the taphole at the bottom of the blast furnace and flow into the main trough. After the hot metal and slag are separated, the hot metal flows into the hot metal ladle through the iron trough, and the slag flows into the slag treatment line through the slag trough. The chemical composition of the hot metal in the hot metal ladle is MFe 95.7%, Sn 0.007%, Cr 0.04%, Cu 0.03%, and the balance is C and some inevitable impurities. The temperature of the hot metal in the hot metal ladle is 1750°C. (2) Atomization: The molten iron flows from the tapping hole at the bottom of the molten iron ladle to the tundish, and then from the tapping hole at the bottom of the tundish into the iron inlet of the atomization device, and a water-powder mixture is obtained through high-pressure water atomization; the high-pressure water atomization uses an annular slit nozzle, the water pressure is 15 MPa, and the water flow rate is 500 Nm 3 / h; (3) Magnetic separation: The water-powder mixture is preliminarily separated by a wet magnetic separator to obtain wet iron powder with a water content of 25%; (4) Dewatering: The wet iron powder with a water content of 25% is dewatered by a filter press to obtain wet iron powder with a water content of 10%; (5) Drying: The wet iron powder with a water content of 10% is dried by a drum dryer to reduce its water content to 0.53% to obtain atomized raw powder at a temperature of 52°C; the heat source of the drum dryer uses low-temperature waste gas with a temperature range of 150°C - 250°C generated by the sintering ring cooler in the steel plant; (6) Screening: The atomized raw powder at a temperature of 52°C is screened with a 40-mesh sieve, and the material passing through the sieve is the atomized iron powder.

[0027] The atomized iron powder prepared by using this production method can be used as a raw material for the production of titanium dioxide by the sulfuric acid method. Its quality meets the requirements of atomized iron powder for the sulfuric acid method of titanium dioxide. Its specific chemical component content is: MFe 90.6%, Sn 0.007%, Cr 0.05%, Cu 0.04%, H2O 0.53%. The mass ratio of the atomized iron powder passing through the 40-mesh particle size screening (-40-mesh powder yield) is 98.5%, and the utilization rate is high.

[0028] The cost of scrap steel is generally 200 yuan / ton - 300 yuan / ton higher than that of molten iron, and the production cost of melting scrap steel in an electric furnace and heating it up to 1750°C, which is the same as that of molten iron, is about 900 yuan / ton - 1200 yuan / ton. Calculated according to a -40-mesh powder yield (the ratio of the powder passing through the 40-mesh sieve to the total atomized raw powder) of 98.5%, the cost of the atomized iron powder obtained by the production method provided by the present invention is 1116 yuan / ton - 1522 yuan / ton lower than that obtained by the traditional production method of the same quality, and 600 yuan / ton - 1000 yuan / ton lower than the production cost of traditional reduced iron powder of the same quality. Using the production method provided by the present invention saves the energy consumption of melting scrap steel and iron blocks. Using the low-temperature waste gas in the steel plant as the drying heat source realizes the efficient utilization of low-temperature waste gas and reduces the drying cost. It is a production method with low cost, high quality, higher scale, energy saving, and circular economy.

[0029] Example 4 A production method of atomized iron powder includes the steps of ironmaking, atomization, magnetic separation, dewatering, drying, cooling, and screening. The specific operation steps are as follows: (1)Ironmaking: The sinter, pellet, lump ore and coke are proportioned according to the conventional ratio in ironmaking in the iron and steel industry, and then charged into the furnace from the top of the blast furnace. After a series of physical and chemical reactions, hot metal and slag are generated and discharged from the taphole at the bottom of the blast furnace and flow into the main trough. After the separation of hot metal and slag, the hot metal flows into the hot metal ladle through the iron trough, and the slag flows into the slag treatment line through the slag trough. The mass ratio of MFe in the hot metal is 95.5%, and the temperature of the hot metal in the hot metal ladle is 1600 °C; (2)Atomization: The hot metal flows from the taphole at the bottom of the hot metal ladle to the tundish, and then flows into the iron inlet of the atomization device from the taphole at the bottom of the tundish, and a water-powder mixture is obtained through high-pressure water atomization; The high-pressure water atomization uses an annular slit nozzle, the water pressure is 13 MPa, and the water flow rate is 400 Nm 3 / h; (3)Magnetic separation: The water-powder mixture is preliminarily separated by a wet magnetic separator to obtain wet iron powder with a water content of 30%; (4)Dewatering: The wet iron powder with a water content of 30% is dewatered by a filter press to obtain wet iron powder with a water content of 15%; (5)Drying: The wet iron powder with a water content of 15% is dried by a drum dryer to reduce its water content to 1.00% to obtain atomized raw powder with a temperature of 100 °C; The heat source of the drum dryer uses low-temperature waste gas with a temperature range of 150 °C - 250 °C generated by the sintering annular cooler in the steel plant; (6)Screening: The atomized raw powder with a temperature of 100 °C is screened with a 200-mesh sieve, and the undersize is the atomized iron powder.

[0030] The atomized iron powder prepared by using this production method can be used as the raw material for Bayer process alumina, and its quality meets the requirements of atomized iron powder for Bayer process alumina. The mass ratio of MFe is 91.5%, the metallization rate is 85.9%, H2O is 1.00%, and the mass ratio of the atomized iron powder passing through the 200-mesh particle size screening (-200-mesh powder yield) is 90.5%.

[0031] The cost of scrap steel is generally 200 - 300 yuan per ton higher than that of hot metal. The production cost of melting scrap steel in an electric furnace and heating it up to 1600 °C, the same temperature as hot metal, is about 800 - 1000 yuan per ton. The -200 mesh powder yield (the ratio of the powder passing through a 200-mesh sieve to the total atomized raw powder) is calculated at 90.5%. The cost of the atomized iron powder obtained by the production method provided by the present invention is 1104 - 1436 yuan per ton lower than that obtained by the traditional production method of the same quality, and 600 - 900 yuan per ton lower than the production cost of the traditional reduced iron powder of the same quality. Using the production method provided by the present invention saves the energy consumption of melting scrap steel and iron blocks. Using the low-temperature waste gas from the steel plant as the drying heat source realizes the efficient utilization of the low-temperature waste gas and reduces the drying cost. It is a production method with low cost, high quality, higher scale, energy saving, and circular economy.

[0032] Example 5 A production method of atomized iron powder, comprising the steps of ironmaking, atomization, magnetic separation, dehydration, drying, cooling, and screening. The specific operation steps are as follows: (1) Ironmaking: Charge sinter, pellet, lump ore, and coke into the furnace from the top of the blast furnace according to the conventional ratio in the ironmaking field of the steel industry. After a series of physical and chemical reactions, hot metal and slag are generated and discharged from the tapping hole at the bottom of the blast furnace and flow into the main trough. After the separation of hot metal and slag, the hot metal flows into the hot metal ladle through the iron trough, and the slag flows into the slag treatment line through the slag trough. The mass ratio of MFe in the hot metal is 95.3%, and the temperature of the hot metal in the hot metal ladle is 1680 °C; (2) Atomization: The hot metal flows from the tapping hole at the bottom of the hot metal ladle to the tundish, and then flows into the iron inlet of the atomization device from the tapping hole at the bottom of the tundish, and a water-powder mixture is obtained through high-pressure water atomization; The high-pressure water atomization uses an annular slit nozzle, the water pressure is 17 MPa, and the water flow rate is 650 Nm 3 / h; (3) Magnetic separation: Use a wet magnetic separator to preliminarily separate the water-powder mixture to obtain wet iron powder with a water content of 28%; (4) Dehydration: Use a filter press to dehydrate the wet iron powder with a water content of 28% to obtain wet iron powder with a water content of 13%; (5) Drying: Use a drum dryer to dry the wet iron powder with a water content of 13% and reduce its water content to 0.87% to obtain atomized raw powder at a temperature of 84 °C; The heat source of the drum dryer uses low-temperature waste gas with a temperature range of 150 °C - 250 °C generated by the sintering ring cooler of the steel plant; (6) Screening: Screen the atomized raw powder at a temperature of 84 °C with a 200-mesh sieve, and the material passing through the sieve is the atomized iron powder.

[0033] The atomized iron powder prepared by using this production method can be used as the raw material for alumina by the Bayer process, and its quality meets the requirements of atomized iron powder for alumina by the Bayer process. The mass ratio of MFe is 91.0%, the metallization rate is 86.2%, H2O is 0.87%, and the mass ratio of the atomized iron powder passing through the 200-mesh particle size screening (-200-mesh powder yield) is 90.6%.

[0034] The cost of scrap steel is generally 200 yuan / ton - 300 yuan / ton higher than that of hot metal, and the production cost of melting scrap steel in an electric furnace and heating it up to 1680°C, which is the same as that of hot metal, is about 860 yuan / ton - 1100 yuan / ton. The -200-mesh powder yield (the ratio of the undersize powder passing through the 200-mesh sieve to the total atomized green powder) is calculated at 90.6%. The cost of the atomized iron powder obtained by the production method provided by the present invention is 1169 yuan / ton - 1545 yuan / ton lower than that obtained by the traditional production method of the same quality, and 650 yuan / ton - 1000 yuan / ton lower than the production cost of the traditional reduced iron powder of the same quality. Using the production method provided by the present invention saves the energy consumption of melting scrap steel and iron blocks, uses the low-temperature waste gas of the steel plant as the drying heat source to achieve the efficient utilization of the low-temperature waste gas and reduce the drying cost, and is a production method with low cost, high quality, higher scale, energy saving, and circular economy.

[0035] Example 6 A production method of atomized iron powder includes the steps of ironmaking, atomization, magnetic separation, dehydration, drying, cooling, and screening. The specific operation steps are as follows: (1) Ironmaking: Charge sinter, pellet, lump ore, and coke in the conventional proportion for ironmaking in the iron and steel field, then input them into the furnace from the top of the blast furnace. After a series of physical and chemical reactions, hot metal and slag are generated and discharged from the tapping hole at the bottom of the blast furnace and flow into the main trough. After the hot metal and slag are separated, the hot metal flows into the hot metal ladle through the iron trough, and the slag flows into the slag treatment line through the slag trough. The mass ratio of MFe in the hot metal is 95.5%, and the temperature of the hot metal in the hot metal ladle is 1750°C; (2) Atomization: The hot metal flows from the tapping hole at the bottom of the hot metal ladle to the tundish, and then flows into the iron inlet of the atomization device from the tapping hole at the bottom of the tundish, and a water-powder mixture is obtained through high-pressure water atomization; High-pressure water atomization uses an annular slit nozzle, the water pressure is 20 MPa, and the water flow rate is 900 Nm 3 / h; (3) Magnetic separation: Use a wet magnetic separator to preliminarily separate the water-powder mixture to obtain wet iron powder with a water content of 25%; (4) Dehydration: Use a filter press to dehydrate the wet iron powder with a water content of 25% to obtain wet iron powder with a water content of 10%; (5) Drying: The wet iron powder with a water content of 10% is dried using a drum dryer, reducing its water content to 0.66% to obtain atomized raw powder at a temperature of 60°C. The heat source of the drum dryer is the low-temperature waste gas with a temperature range of 150°C - 250°C generated by the sintering ring cooler of the steel plant. (6) Screening: The atomized raw powder at a temperature of 60°C is screened using a 200-mesh sieve, and the material passing through the sieve is the atomized iron powder.

[0036] The atomized iron powder prepared by using this production method can be used as the raw material for Bayer process alumina, and its quality meets the requirements of the atomized iron powder for Bayer process alumina. The mass ratio of MFe is 90.7%, the metallization rate is 86.5%, H2O is 0.66%, and the mass ratio of the atomized iron powder passing through the 200-mesh particle size screening (-200-mesh powder yield) is 90.5%.

[0037] The cost of scrap steel is generally 200 - 300 yuan / ton higher than that of hot metal, and the production cost of melting scrap steel in an electric furnace and heating it up to 1750°C, which is the same as that of hot metal, is about 900 - 1200 yuan / ton. Calculated based on the -200-mesh powder yield (the ratio of the powder passing through the 200-mesh sieve to the total atomized raw powder) of 90.5%, the cost of the atomized iron powder obtained by the production method provided by the present invention is 1215 - 1657 yuan / ton lower than that obtained by the traditional production method of the same quality, and 700 - 1100 yuan / ton lower than the production cost of the traditional reduced iron powder of the same quality. Using the production method provided by the present invention saves the energy consumption of melting scrap steel and iron blocks, uses the low-temperature waste gas of the steel plant as the drying heat source to achieve the efficient utilization of the low-temperature waste gas and reduce the drying cost. It is a production method with low cost, high quality, higher scale, energy saving, and circular economy.

[0038] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, those of ordinary skill in the art can make various equivalent modifications or substitutions to the embodiments of the present invention, and all such modifications or substitutions should be within the scope of the present invention. / Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention.

Claims

1. A production method of atomized iron powder, characterized in that, Atomized iron powder is obtained through the steps of iron smelting, atomization, magnetic separation, dehydration, drying, cooling and screening in sequence; among them, iron smelting is to smelt at least one of sinter, pellet and lump ore into molten iron, the temperature of the molten iron is 1600-1750 °C, and by mass percentage, the MFe content in the molten iron is ≥94.0%; atomization is that the molten iron is atomized by high-pressure water to obtain a water-powder mixture, an annular slit nozzle is used for atomization, the water pressure is 10-20 MPa, and the water flow rate is 250-900 Nm 3 / h.

2. The production method of atomized iron powder according to claim 1, characterized in that, Ironmaking is to smelt sinter, pellet, lump ore and coke into hot metal in a blast furnace.

3. The production method of atomized iron powder according to claim 1, characterized in that, Magnetic separation is to preliminarily separate the water-powder mixture with a wet magnetic separator to obtain wet iron powder with a water content of 25%-30%.

4. The production method of atomized iron powder according to claim 3, characterized in that, Dewatering is to dewater the wet iron powder obtained by magnetic separation with a filter press to obtain wet iron powder with a water content of 10%-15%.

5. The production method of atomized iron powder according to claim 4, characterized in that, Drying is to dry the wet iron powder with a water content of 10%-15% obtained after dewatering to obtain atomized raw powder; the water content of the atomized raw powder ≤1.0%, and the dried atomized raw powder ≤100°C.

6. The production method of atomized iron powder according to claim 5, characterized in that, The drying equipment uses a drum dryer; the heat source of the drum dryer uses low-temperature waste gas with a temperature range of 150°C-250°C generated by a sintering ring cooler.

7. The production method of atomized iron powder according to claim 5, characterized in that, Screening is to screen the atomized raw powder obtained by drying, and the material passing through the screen is atomized iron powder.

8. The production method of atomized iron powder according to claim 1, characterized in that, It includes the following steps: (1) Ironmaking: After proportioning sinter, pellet, lump ore and coke, put them into the blast furnace, react to generate hot metal and slag, separate the hot metal and slag, and the hot metal flows into the hot metal ladle. By mass percentage, MFe in the hot metal ≥95.5%, and the temperature of the hot metal in the hot metal ladle is 1600-1750°C; (2) Atomization: The molten iron flows into the atomization device and is atomized by high-pressure water to obtain a water-powder mixture; the high-pressure water atomization uses an annular slit nozzle, the water pressure is 10-15 MPa, and the water flow rate is 250-500 Nm 3 / h; (3) Magnetic separation: Use a wet magnetic separator to preliminarily separate the water-powder mixture to obtain wet iron powder with a water content of 25%-30%; (4) Dewatering: Use a filter press to dewater the wet iron powder obtained by magnetic separation to obtain wet iron powder with a water content of 10%-15%; (5) Drying: Use a drum dryer to dry the wet iron powder obtained after dewatering, with its water content ≤1.0% to obtain atomized raw powder with a temperature ≤100°C; the heat source of the drum dryer uses low-temperature waste gas with a temperature range of 150°C-250°C generated by a sintering ring cooler; (6) Screening: Screen the dried atomized raw powder with a 40-mesh sieve, and the material passing through the screen is atomized iron powder; In the atomized iron powder, MFe≥90%, Sn≤0.01%, Cr≤0.10%, Cu≤0.50%, H2O≤1.0%, which is used as atomized iron powder for sulfuric acid process titanium dioxide.

9. The production method of atomized iron powder according to claim 1, characterized in that, It includes the following steps: (1) Ironmaking: After proportioning sinter, pellet, lump ore and coke, put them into the blast furnace, react to generate hot metal and slag, separate the hot metal and slag, and the hot metal flows into the hot metal ladle. By mass percentage, MFe in the hot metal ≥94.0%, and the temperature of the hot metal in the hot metal ladle is 1600-1750°C; (2) Atomization: The molten iron flows into the atomization device and is atomized by high-pressure water to obtain a water-powder mixture; the high-pressure water atomization uses an annular slit nozzle, the water pressure is 13 - 20 MPa, and the water flow rate is 400 - 900 Nm 3 / h; (3) Magnetic separation: Use a wet magnetic separator to preliminarily separate the water-powder mixture to obtain wet iron powder with a water content of 25%-30%; (4) Dewatering: Use a filter press to dewater the wet iron powder obtained by magnetic separation to obtain wet iron powder with a water content of 10%-15%; (5) Drying: Use a drum dryer to dry the wet iron powder obtained after dewatering, with its water content ≤1.0% to obtain atomized raw powder with a temperature ≤100°C; the heat source of the drum dryer uses low-temperature waste gas with a temperature range of 150°C-250°C generated by a sintering ring cooler; (6) Screening: Screen the dried atomized raw powder with a 200-mesh sieve, and the material passing through the screen is atomized iron powder; The mass proportion of MFe in the atomized iron powder is ≥90.0%, the metallization rate is ≥85.0%, and the mass proportion of the -200 mesh size is ≥90%, which is used as the atomized iron powder for Bayer process alumina.

10. An atomized iron powder, characterized in that, It is prepared by the production method of the atomized iron powder according to any one of claims 1-9.