Hydrogen-based magnetocaloric rotary kiln type iron ore fines direct reduction device

Abstract

This invention relates to the field of metallurgical equipment technology, specifically disclosing a hydrogen-based magnetothermal rotary kiln direct reduction device for iron ore powder. The device includes a feed hopper connected to a feeding screw to deliver iron ore powder into the rotary kiln; the head of the rotary kiln is connected to a kiln head hood, and the discharge hopper is also connected to the kiln head hood. A discharge screw is connected to the kiln head hood to facilitate the discharge of reduced iron powder. The discharge screw is water-cooled to lower the temperature of the reduction product. An induction coil heating system is arranged on the outside of the rotary kiln to provide the heat required for the reduction reaction. The invention features annular storage grooves distributed within the rotary kiln, and spiral grooves axially arranged on the inner wall of the preheating zone at the kiln tail end to transport iron ore powder to the reduction zone in the middle of the kiln. The number of annular storage grooves in the reduction zone in the middle of the kiln is less than the number of spiral grooves axially arranged on the inner wall of the preheating zone at the kiln tail end, thereby reducing the speed at which iron ore powder is transported to the cooling zone at the kiln head end, increasing the residence time of the iron ore powder and reduction product within the kiln, and ensuring a complete reduction reaction.

Description

Technical Field

[0001] This invention relates to the field of metallurgical equipment technology, and in particular to a hydrogen-based magnetothermal rotary kiln direct reduction device for iron ore powder. Background Technology

[0002] In the metallurgical industry, the reduction of iron oxides is a crucial step in the production of metallic iron. Existing hydrogen reduction technologies, such as shaft furnaces, fluidized bed processes, and smelting reduction methods, each have their shortcomings. While shaft furnaces are simple to operate, they suffer from poor heat and mass transfer, resulting in low reduction efficiency and stringent requirements for raw material particle size and shape. Fluidized bed processes offer good heat and mass transfer, but the bed is unstable during operation, leading to frequent material entrainment, fluctuations in product quality and yield, and high maintenance costs. Smelting reduction methods are energy-intensive, operate at high temperatures, and incur high equipment investment and operating costs, while also generating significant amounts of heat and gas, necessitating additional environmental protection measures. Rotary kilns, as continuous reaction devices, offer advantages such as large throughput, stable operation, and uniform reaction. However, traditional rotary kilns are primarily used in high-temperature roasting or calcination processes. Although coal-based rotary kiln iron reduction technology is widely used, the harmful gases produced by coal combustion severely pollute the environment, resulting in high energy consumption, low utilization rates, and unstable product quality, making it difficult to meet the production requirements of high-purity metallic iron.

[0003] Therefore, developing a rotary kiln device specifically for hydrogen reduction of iron ore powder can not only fully utilize the advantages of rotary kilns, but also effectively solve the shortcomings of existing technologies, and has important industrial application value and broad market prospects. Summary of the Invention

[0004] In view of the above situation, the purpose of this invention is to provide a hydrogen-based magnetothermal rotary kiln direct reduction device for iron ore powder, which aims to achieve efficient reduction of iron oxides and sustainable utilization of resources by optimizing the equipment structure and operating conditions, so as to meet the dual requirements of environmental protection and high efficiency in modern metallurgical industry.

[0005] To achieve the above objectives, the technical solution adopted by this invention is as follows: A hydrogen-based magnetothermal rotary kiln direct reduction device for iron ore powder is provided, comprising: a feed hopper, a feeding screw, a rotary kiln, lifting fan blades, a rotating shaft, a built-in motor, a water cooling device, a rotary kiln head cover, a discharge hopper, a discharge screw, and an induction coil heating system. The feed hopper is connected to the feeding screw, which feeds the iron ore powder into the rotary kiln. The head of the rotary kiln is connected to the kiln head cover, the discharge hopper is connected to the kiln head cover, and the discharge screw is connected to the kiln head cover to facilitate the discharge of reduced iron powder. The discharge screw is water-cooled to reduce the temperature of the reduction product. The induction coil heating system is arranged outside the rotary kiln to provide the heat required for the reduction reaction. A water cooling device is installed radially outside the rotary kiln head to the built-in motor.

[0006] The rotary kiln has three equidistant circular storage grooves distributed axially in the preheating zone at the kiln tail end, which are used as storage tanks for iron ore powder. Six spiral grooves are axially arranged on the inner wall of the preheating zone at the kiln tail end to transport iron ore powder to the reduction zone in the middle of the kiln.

[0007] The rotary kiln has six equidistant circular storage grooves distributed axially in the reduction zone at the middle of the kiln, which serve as storage tanks for iron ore powder and reduction products. There are four spiral grooves axially arranged on the inner wall of the reduction zone at the middle of the kiln, which is fewer than the six spiral grooves axially arranged on the inner wall of the preheating zone at the tail end of the kiln. This reduces the speed at which iron ore powder is transported to the cooling zone at the head end of the kiln, increases the residence time of iron ore powder and reduction products in the kiln, and ensures that the reduction reaction is fully carried out.

[0008] The rotary kiln has three equidistant annular storage grooves axially distributed in the cooling zone at the kiln head end, which serve as storage troughs for the reduction products. Eight spiral grooves are axially arranged on the inner wall of the cooling zone at the kiln head end, which is more than the four spiral grooves axially arranged in the reduction zone at the middle of the kiln and the six spiral grooves axially arranged in the preheating zone at the kiln tail end. This increases the speed at which the reduction products are transported to the discharge end of the kiln head, reduces the residence time of the reduction products in the kiln, and ensures that the reduction products are smoothly discharged from the rotary kiln.

[0009] The rotary kiln has a storage groove with a height equal to twice that of other storage grooves, located between the end of the preheating zone at the kiln tail and the reduction zone at the kiln middle. This groove is used to store iron ore powder transferred from the preheating zone at the kiln tail, thus solving the problem of iron ore powder transfer speed caused by the different number of spiral grooves between the preheating zone at the kiln tail and the reduction zone at the kiln middle.

[0010] The rotary kiln has three support arm structures fixed to the inner side of its tail end by welding. The support arms are distributed in a 120° circumferential direction and are used to support the rotating shaft.

[0011] The rotary kiln has four support arm structures fixed at the end of the cooling zone by welding. The support arms are distributed in a 90° circumferential direction and are used to support the rotating shaft.

[0012] The rotor of the built-in motor is connected to the rotating shaft near the head end of the rotary kiln. The motor stator winding is fixed to the inner wall of the rotary kiln and surrounds the built-in motor rotor. The motor stator core is fixed to the inner wall of the rotary kiln and surrounds the motor stator winding. The motor unit is completely placed in the rotary kiln, eliminating the need for an external transmission device, reducing energy loss, and saving the sealing process for connecting the rotating shaft and the rotary kiln.

[0013] The rotation direction of the built-in motor rotor is opposite to that of the rotary kiln. The vertical distance between the inner diameter of the motor stator winding and the discharge spiral at the kiln tail section and the axis of the rotary kiln is equal, ensuring that the reduction products transmitted from the spiral groove in the cooling zone at the kiln head can be discharged smoothly.

[0014] The lifting fan blades are fixed axially along the rotation axis by welding, corresponding to three equidistant annular storage grooves in the preheating zone at the kiln tail, six equidistant annular storage grooves in the reduction zone at the kiln middle, and three equidistant annular storage grooves in the cooling zone at the kiln head. These blades are used to lift iron ore powder or reduction products from the annular grooves, and are distributed circumferentially at 120°. The rotation direction of the rotation axis is opposite to that of the rotary kiln, increasing the relative speed between the tip of the lifting fan blades and the grooves on the inner wall of the rotary kiln, promoting the lifting of iron ore powder, accelerating the reduction reaction, and preventing material adhesion.

[0015] The beneficial effects of this invention are: by optimizing the structural design and motor arrangement, the reduction efficiency is improved and the product quality is guaranteed; by distributing annular storage grooves in the rotary kiln and axially setting spiral grooves on the inner wall of the preheating zone at the kiln tail end, iron ore powder is conveyed to the reduction zone in the middle of the kiln; the number of annular storage grooves in the reduction zone in the middle of the kiln is less than the number of spiral grooves axially set on the inner wall of the preheating zone at the kiln tail end, so as to reduce the speed of conveying iron ore powder to the cooling zone at the kiln head end, increase the residence time of iron ore powder and reduction products in the kiln, and ensure that the reduction reaction is fully carried out. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the rotary kiln device for hydrogen reduction of iron ore powder according to the present invention. Figure 2 This is a schematic diagram of the cross-sectional structure of the rotary kiln of the present invention; Figure 3 This is a schematic diagram of the rotating shaft of the present invention.

[0017] In the diagram: 1. Feed hopper; 2. Rotary kiln; 2-1. Cross support structure; 2-2. Trident support structure; 2-3. (Kiln tail end) Circular storage groove; 2-4. (Kiln tail end) Spiral groove; 2-5. Storage groove twice the height; 2-6. (Kiln middle end) Circular storage groove; 2-7. (Kiln middle end) Spiral groove; 2-8. (Kiln head end) Spiral groove; 2-9. (Kiln head end) Circular storage groove; 3. Induction coil; 4. Motor stator winding; 5. Motor stator core; 6. Water cooling device; 7. Rotary kiln head cover; 8. ; 9. Discharge screw; 11. Motor rotor; 12. Rotating shaft; 12-1. Lifting fan blades; 13. Feeding screw; Detailed Implementation

[0018] The following examples illustrate this embodiment.

[0019] like Figure 1-2As shown, this application provides a hydrogen-based magnetothermal rotary kiln direct reduction device for iron ore powder. The bottom of its feed hopper is connected to a feeding screw to ensure that the iron ore powder can continuously and uniformly enter the rotary kiln, which is driven by a motor. The feeding screw is made of high-temperature resistant material and, driven by the motor, transports the iron ore powder from the feed hopper to the rotary kiln inlet. The main body of the rotary kiln is a cylindrical structure with radially arranged grooves on its inner wall for storing iron ore powder and extending the residence time. An induction coil heating system is installed on the outer wall of the rotary kiln, with the induction coils distributed in a spiral pattern to ensure uniform heat transfer. The outlet at the head end of the rotary kiln is connected to the rotary kiln head cover. The rotary kiln head hood is connected to the discharge hopper, and the discharge screw conveys the reduced iron powder to the collection device. The induction coil heating system adopts high-frequency induction heating technology. The induction coils are arranged around the outer wall of the rotary kiln and controlled in sections to ensure uniform temperature in different areas. The temperature inside the rotary kiln can be controlled between 700℃ and 900℃ to meet the reduction reaction requirements of iron ore powder. The temperature inside the rotary kiln is monitored by thermocouples, and the power of the induction coils is adjusted in real time to ensure temperature stability. A water cooling device is installed on the outer side of the radial rotary kiln head with the built-in motor rotor to prevent the high temperature inside the rotary kiln from affecting the normal operation of the motor.

[0020] like Figure 3 As shown, the rotating shaft is mounted on the three-pronged support structure at the tail end and the cross support structure at the head end of the rotary kiln via bearings; the material lifting fan blades are fixed to the rotating shaft by welding, with a set of 3 blades, distributed circumferentially at 120° and along the axial direction of the rotating shaft, to ensure that the material is fully lifted in the rotary kiln.

[0021] The built-in motor rotor is installed inside the rotary kiln head and is directly connected to the rotating shaft via a coupling; the motor stator core and motor stator winding are installed on the inner wall of the rotary kiln head and surround the built-in motor rotor circumferentially; the motor unit is completely placed in the rotary kiln, eliminating the need for an external transmission device, reducing energy loss, and saving the sealing process for connecting the rotating shaft and the rotary kiln.

[0022] The built-in motor rotor rotates in the opposite direction to the rotary kiln. The vertical distance between the inner diameter of the motor stator winding and the discharge spiral at the kiln tail section and the axis of the rotary kiln is equal, ensuring that the reduction products transmitted from the spiral groove in the cooling zone at the kiln head can be discharged smoothly. The lifting fan blades rotate synchronously with the rotating shaft, and the rotation direction of the rotating shaft is opposite to that of the rotary kiln. This increases the relative speed between the end of the lifting fan blades and the groove in the inner wall of the rotary kiln, ensuring that the iron ore powder is fully scattered, accelerating the reduction reaction, and preventing material adhesion.

[0023] like Figure 2As shown, the rotary kiln has three equidistant axially distributed annular storage grooves in the preheating zone at the kiln tail end, serving as storage tanks for iron ore powder. Six spiral grooves are axially arranged on the inner wall of the preheating zone at the kiln tail end to convey iron ore powder to the reduction zone in the middle of the kiln. In the reduction zone in the middle of the kiln, six equidistant axially distributed annular storage grooves are used as storage tanks for iron ore powder and reduction products. Four spiral grooves are axially arranged on the inner wall of the reduction zone in the middle of the kiln, fewer than the six spiral grooves axially arranged in the preheating zone at the kiln tail end. This reduces the speed at which iron ore powder is conveyed to the cooling zone at the kiln head end, increasing the residence time of the iron ore powder and reduction products in the kiln, ensuring a complete reduction reaction. Three annular storage grooves are equidistantly distributed in the cooling zone at the kiln head end. The annular storage groove, used as a storage tank for reduction products, has eight spiral grooves axially arranged on the inner wall of the cooling zone at the kiln head. This number is greater than the four spiral grooves axially arranged in the reduction zone at the middle of the kiln and the six spiral grooves axially arranged in the preheating zone at the kiln tail. This increases the speed at which reduction products are transported to the discharge end of the kiln head, reduces the residence time of reduction products in the kiln, and ensures that reduction products are smoothly discharged from the rotary kiln. At the end of the preheating zone at the kiln tail and between the reduction zone at the middle of the kiln, there is a storage groove with a height equal to twice that of the other storage grooves. This is used to store iron ore powder transferred from the preheating zone at the kiln tail, thus solving the problem of iron ore powder transfer speed caused by the different number of spiral grooves in the preheating zone at the kiln tail and the reduction zone at the middle of the kiln.

[0024] The lifting fan blades are fixed axially along the rotation axis by welding, corresponding to three equidistant circular storage grooves in the preheating zone at the kiln tail end, six equidistant circular storage grooves in the reduction zone at the kiln middle end, and three equidistant circular storage grooves in the cooling zone at the kiln head end. They are used to lift iron ore powder or reduction products from the circular grooves, and are distributed circumferentially at 120°.

[0025] Three support arm structures are welded to the inner side of the tail end of the rotary kiln. The support arms are distributed circumferentially at 120° and are used to support the rotating shaft. Four support arm structures are welded to the end of the cooling zone of the rotary kiln. The support arms are distributed circumferentially at 90° and are used to support the rotating shaft. Operating procedures

[0026] Feeding: Dry iron ore powder with TFe=7% and particle size of -200 mesh is fed into the feed hopper. The iron ore powder is then fed into the tail end of the rotary kiln through the feed hopper and the feeding screw. Heating and reduction: Start the induction coil heating system to raise the temperature inside the rotary kiln to the set value (e.g., 800 ℃), and at the same time, introduce hydrogen gas (e.g., flow rate of 10 L / min) from the rotary kiln head cover, with the hydrogen gas flow direction opposite to the material conveying direction; Mixing and lifting: Start the motor to drive the rotary kiln at a speed of 1 rad / min, start the built-in motor to drive the rotating shaft and lifting fan blades at a speed of 1 rad / min, keep the rotation direction of the rotary kiln and the lifting fan blades opposite to ensure that the iron ore powder is fully spread; Discharge: The reduced iron powder is conveyed to the collection device through the discharge screw, and the discharge screw is cooled by water cooling.

[0027] Through the above embodiments, the present invention provides an efficient and reliable rotary kiln device for hydrogen reduction of iron ore powder, which can significantly improve reduction efficiency, reduce energy consumption, and improve product quality.

Claims

1. A hydrogen-based magnetothermal rotary kiln direct reduction device for iron ore powder, characterized in that, It includes a feed hopper, a feeding screw, a rotary kiln, a rotating shaft, a built-in motor, a water cooling device, a rotary kiln head cover, a discharge hopper, a discharge screw, and an induction coil heating system; wherein, the feed hopper is connected to the feeding screw, the feeding screw is connected to the rotary kiln, the rotary kiln head is connected to the rotary kiln head cover, the rotary kiln head cover is connected to the discharge hopper, the discharge hopper is connected to the discharge screw, the induction coil heating system is distributed on the outside of the rotary kiln, and the lifting fan blades are fixed along the axial direction of the rotating shaft; The rotary kiln is arranged horizontally; the inner wall of the rotary kiln is radially provided with annular grooves and axially provided with spiral grooves to transfer iron ore powder and reduction products from the kiln tail to the kiln head; the tail end and the head end of the rotary kiln are respectively fixed to two sets of support arm structures on the inner side of the rotary kiln by welding to support the rotating shaft; the rotor of the built-in motor is connected to the rotating shaft near the head end of the rotary kiln, and a water cooling device is provided on the outer side of the kiln head of the built-in motor. The rotary kiln has annular storage grooves equidistantly distributed axially in the preheating zone at the kiln tail end, which serve as storage troughs for iron ore powder; and spiral grooves are axially arranged on the inner wall of the preheating zone at the kiln tail end to transport iron ore powder material to the reduction zone in the middle of the kiln. The rotary kiln has annular storage grooves equidistantly distributed axially in the reduction zone at the middle of the kiln, which serve as storage tanks for iron ore powder and reduction products; and spiral grooves are axially arranged on the inner wall of the reduction zone at the middle of the kiln. The rotary kiln has annular storage grooves equidistantly distributed axially in the cooling zone at the kiln head end, which serve as storage tanks for reduction products, and spiral grooves axially arranged on the inner wall of the cooling zone at the kiln head end.

2. The hydrogen-based magnetothermal rotary kiln direct reduction device for iron ore powder according to claim 1, characterized in that, The rotary kiln has three annular storage grooves equidistantly distributed axially in the preheating zone at the kiln tail end; six annular storage grooves equidistantly distributed axially in the reduction zone at the kiln middle end; three annular storage grooves equidistantly distributed axially in the cooling zone at the kiln head end; and a storage groove with a height equal to twice that of the other storage grooves is provided between the end of the preheating zone at the kiln tail end and the reduction zone at the kiln middle end.

3. The hydrogen-based magnetothermal rotary kiln direct reduction device for iron ore powder according to claim 1, characterized in that, The rotary kiln has six spiral grooves axially arranged on the inner wall of the preheating zone at the kiln tail end and four spiral grooves axially arranged on the inner wall of the reduction zone at the kiln middle end. The number of spiral grooves is less than the six spiral grooves axially arranged on the inner wall of the preheating zone at the kiln tail end, which reduces the speed at which iron ore powder is conveyed to the cooling zone at the kiln head end. The cooling zone at the kiln head end has eight spiral grooves axially arranged on the inner wall. The number of spiral grooves is greater than the four spiral grooves axially arranged on the inner wall of the reduction zone at the kiln middle end and the six spiral grooves axially arranged on the inner wall of the preheating zone at the kiln tail end, which increases the speed at which the reduction product is conveyed to the discharge end at the kiln head end. The spiral groove of the preheating section runs through the kiln tail section, and the spiral groove of the cooling section extends along the kiln head section to the front of the built-in motor.

4. The hydrogen-based magnetothermal rotary kiln direct reduction device for iron ore powder according to claim 1, characterized in that, The rotating shaft has its lifting fan blades fixed along the axial direction of the rotating shaft and distributed in a circumferential 120° pattern. These blades correspond to three equidistant circular storage grooves in the preheating zone at the kiln tail end, six equidistant circular storage grooves in the reduction zone at the kiln middle end, and three equidistant circular storage grooves in the cooling zone at the kiln head end.

5. The hydrogen-based magnetothermal rotary kiln direct reduction device for iron ore powder according to claim 1, characterized in that, The rotor of the built-in motor is connected to the rotating shaft near the head end of the rotary kiln. The motor stator winding is fixed to the inner wall of the rotary kiln and surrounds the built-in motor rotor. The motor stator core is fixed to the inner wall of the rotary kiln and surrounds the motor stator winding. The motor unit is completely placed in the rotary kiln. The rotation direction of the built-in motor rotor is opposite to that of the rotary kiln, and the vertical distance between the inner diameter of the motor stator winding and the discharge spiral at the kiln tail section and the axis of the rotary kiln is equal.

6. The hydrogen-based magnetothermal rotary kiln direct reduction device for iron ore powder according to claim 1, characterized in that, Three support arm structures are fixed to the inner side of the tail end of the rotary kiln by welding. The support arms are distributed in a 120° circumferential direction to support the rotating shaft.

7. The hydrogen-based magnetothermal rotary kiln direct reduction device for iron ore powder according to claim 1, characterized in that, At the end of the rotary kiln cooling zone, four support arm structures are fixed by welding. The support arms are distributed circumferentially at 90° and are used to support the rotating shaft.

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