Iron red preparation system based on electromagnetic heating rotary kiln

Abstract

The utility model relates to iron red preparation technical field, especially based on a kind of iron red preparation system of electromagnetic heating rotary kiln, including rotary kiln and respectively connecting its entrance and outlet raw material feeding device, tail gas treatment device, the kiln body of rotary kiln is by the magnetically permeable layer, stainless steel layer and heat preservation insulating layer sequentially connected from inside to outside, at least one group of electromagnetic induction coil that spiral arrangement exists spacing between electromagnetic induction coil and kiln body outer wall when being electrified with magnetically permeable layer generates electromagnetic induction, spiral guide plate is also spirally arranged on the inner wall of magnetically permeable layer, when kiln body rotates, internal raw material is guided by spiral guide plate from the entrance of rotary kiln to export.The utility model's rotary kiln rotates, and electromagnetic heating directly acts on kiln body, internal raw material is guided by spiral guide plate from the entrance of rotary kiln to export, and heat efficiency is as high as 90% or more, compared with traditional gas heating, and energy utilization rate is improved and pollution is reduced.

Description

Technical Field

[0001] This utility model relates to the field of iron oxide preparation technology, and in particular to an iron oxide preparation system based on an electromagnetically heated rotary kiln. Background Technology

[0002] High-purity iron oxide red can be used as a raw material for preparing high-grade permanent magnet ferrite pre-sintered materials, and can also be applied in industries such as coatings, lithium iron phosphate, inks, rubber, and ceramics, showing broad application prospects. Traditional iron oxide red preparation methods mainly include wet methods (such as the ferrous sulfate oxidation method) and dry methods (such as the rotary kiln calcination method). Among them, the rotary kiln calcination method has the advantages of simple process and high output, but traditional rotary kilns use gas or coal for heating, which has problems such as high energy consumption, high pollution, easy oxidation, and low temperature control accuracy.

[0003] Electromagnetic heating technology boasts advantages such as high efficiency, energy saving, and environmental friendliness, but it is not yet widely applied in the preparation of iron oxide red in rotary kilns. Therefore, there is an urgent need to develop an iron oxide red preparation system and method based on electromagnetically heated rotary kilns to improve energy utilization, reduce pollution emissions, and optimize product quality. Utility Model Content

[0004] To address the above technical issues, this invention provides an iron oxide red preparation system based on an electromagnetically heated rotary kiln. Electromagnetic induction coils are spirally arranged outside the kiln, and a spiral guide plate is installed inside the kiln. When the rotary kiln rotates, electromagnetic heating directly acts on the kiln body, and the raw materials inside are guided from the inlet to the outlet of the rotary kiln along the spiral guide plate. The thermal efficiency is as high as 90% or more, saving more than 30% energy compared to traditional gas heating.

[0005] The iron oxide red preparation system based on electromagnetic heating rotary kiln in this scheme includes a rotary kiln and a raw material feeding device and a tail gas treatment device connected to its inlet and outlet, respectively. The kiln body is composed of a magnetic conductive layer, a stainless steel layer and a heat insulation layer connected sequentially from the inside to the outside. At least one set of electromagnetic induction coils that generate electromagnetic induction with the magnetic conductive layer when energized are spirally arranged on the outside of the kiln body, and there is a gap between the electromagnetic induction coils and the outer wall of the kiln body. A spiral guide plate is also spirally arranged on the inner wall of the magnetic conductive layer so that the raw material inside is guided from the inlet to the outlet of the rotary kiln along the spiral guide plate when the kiln body rotates.

[0006] Furthermore, the electromagnetic induction coils are arranged in four groups from the inlet to the outlet of the rotary kiln. The first group is the preheating section, the second and third groups are both reaction sections, and the fourth group is the heat preservation section. Each group of electromagnetic induction coils is equipped with a high-temperature thermocouple.

[0007] Furthermore, the raw material feeding device includes a feeding bin and a screw feeder connected thereto, with the end of the screw feeder away from the feeding bin connected to the inlet of the rotary kiln.

[0008] Furthermore, the feed hopper has a volume of 3m³, and the screw feeder has an inner diameter of 200mm and a pitch of 150mm.

[0009] Furthermore, the exhaust gas treatment device includes a bag filter and an induced draft fan connected thereto, the bag filter being connected to the outlet of the rotary kiln.

[0010] Furthermore, the thermal insulation layer is composed of a 50mm thick nano-aerogel felt layer and a 30mm thick aluminum silicate fiber blanket layer.

[0011] Furthermore, the rotary kiln is connected to a drive system consisting of a 7.5kW variable frequency motor and a gear reducer with a speed ratio of 1:35.

[0012] Furthermore, the electromagnetic induction coil is made of copper tubing.

[0013] The beneficial effects of this utility model are as follows: Electromagnetic induction coils are spirally arranged outside the kiln body, and a spiral guide plate is installed inside the kiln body. When the rotary kiln rotates, electromagnetic heating directly acts on the kiln body. The raw materials inside are guided from the inlet to the outlet of the rotary kiln along the spiral guide plate, achieving a thermal efficiency of over 90%, saving more than 30% energy compared to traditional gas heating. Simultaneously, multiple sets of electromagnetic induction coils are arranged in the iron oxide red preparation system, and the entire kiln body is designed as an independent preheating section, reaction section, and insulation section. This allows for rapid heating and precise temperature control in different sections of the kiln body, optimizing the temperature control accuracy of each section and improving the purity and color of the iron oxide red. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the iron oxide red preparation system in a specific embodiment of this utility model;

[0015] Figure 2 This is a side view of the rotary kiln in a specific embodiment of the present invention.

[0016] Figure 3 This is a schematic diagram of the spiral guiding mechanism in a specific embodiment of the present utility model;

[0017] Among them: 1. Feeding bin; 2. Screw propeller feeder; 3. Rotary kiln; 4. Electromagnetic induction coil; 5. High temperature thermocouple; 6. Electromagnetic heating controller; 7. Bag dust collector; 8. Exhaust fan; 9. Thermal insulation layer; 10. Stainless steel layer; 11. Magnetic conductive layer; 12. Screw guide mechanism; 12a. Screw guide plate. Detailed Implementation

[0018] This embodiment provides a red iron oxide preparation system based on an electromagnetically heated rotary kiln, referencing... Figure 1The system mainly includes core components such as rotary kiln 3, raw material feeding device, tail gas treatment device and temperature control device.

[0019] Rotary kiln 3 is a composite structure, see reference. Figure 2 The rotary kiln 3 consists of a magnetically conductive layer 11, a stainless steel layer 10, and a thermal insulation layer 9 connected sequentially from the inside out. The inner wall of the magnetically conductive layer 11 has a spiral material guiding mechanism 12 for guiding the material. The outer layer is made of stainless steel, providing mechanical support and shielding against external electromagnetic interference, while the inner layer is made of magnetically conductive alloy steel with good magnetic permeability. The electromagnetic induction coil 4 adopts a four-segment independent winding design (1# is the preheating segment, 2# and 3# are the reaction segments, and 4# is the insulation segment), with each segment being 1.2m long. It is made of copper tubing and equipped with a water-cooling structure to ensure stable operation over a long period of time. Each segment of the coil can be powered by a frequency converter to achieve independent temperature control, thereby achieving precise temperature control.

[0020] The outermost thermal insulation layer 9 of the kiln body adopts a composite structure of nano-aerogel felt (50mm thick) and aluminum silicate fiber blanket (30mm thick), with the overall thermal conductivity controlled below 0.03W / (m·K), effectively reducing heat loss. The drive system of the rotary kiln 3 consists of a 7.5kW variable frequency motor and a gear reducer with a speed ratio of 1:35, which can achieve precise speed adjustment.

[0021] In this embodiment, the feed hopper 1 of the raw material feeding device has a volume of 3m³, and the screw propeller feeder 2 adopts a design with a diameter of 200mm and a screw pitch of 150mm. The feed speed can be adjusted within the range of 3-4.5Hz by frequency conversion speed regulation. The feed speed can be adjusted within a certain range to feed iron concentrate into the rotary kiln 3 evenly.

[0022] The exhaust gas treatment device in this embodiment consists of a bag filter 7 and an induced draft fan 8, which is used to purify the exhaust gas and provide power to discharge the exhaust gas into the atmosphere. The frequency converter-controlled induced draft fan 8 provides stable negative pressure power for the entire exhaust gas treatment process. The dust removal efficiency of the bag filter 7 is not less than 90%, ensuring that the exhaust gas emission meets the standards.

[0023] In some specific embodiments, this iron oxide red preparation system can be equipped with a temperature control device, specifically including a high-temperature thermocouple 5 and an electromagnetic heating controller 6. The temperature control device can independently control the four functional sections of the rotary kiln 3: the temperature control range of the preheating section #1 is 550-600℃; the temperature control range of the reaction sections #2 and #3 is 600-700℃; and the temperature control range of the insulation section #4 is 600-650℃. Each section is equipped with a high-temperature thermocouple 5 for temperature monitoring, with a temperature measurement accuracy of ±1℃. The system uses an advanced PID algorithm to adjust the frequency converter output, achieving rapid temperature control with a system response time of less than 0.5 seconds.

[0024] See Figure 3The spiral material guiding mechanism 12 is specifically a plurality of spiral material guiding plates 12a arranged spirally on the inner wall of the magnetic conductive layer 11. When the kiln rotates, the iron oxide raw material inside is gradually guided from the inlet of the rotary kiln 3 to the outlet along the spiral material guiding plates 12a. In this embodiment, the plurality of spiral material guiding plates 12a are arranged in a spiral in a circle. In some other embodiments, the size of the spiral material guiding plates 12a can be smaller, and several spiral material guiding plates 12a are arranged in multiple circles on the inner wall of the magnetic conductive layer 11.

[0025] Iron concentrate (TFe≥72.0%) is selected as the raw material and fed into the rotary kiln 3 via a screw feeder 2, with the feeding frequency controlled at 3-4.5Hz. The iron concentrate is calcined at 550-700℃ with the addition of an oxidant for more than 1 hour. The power of the electromagnetic induction coil 4 is adjustable to ensure uniform heating of the material. The calcined iron oxide red is discharged through the kiln outlet after cooling. The product has high purity, with its Fe2O3 content consistently around 99%.

[0026] The iron oxide red preparation system based on electromagnetic heating rotary kiln of this invention underwent a comprehensive performance comparison test with the traditional gas-fired rotary kiln system under the same raw material conditions.

[0027] Experimental data show that the unit energy consumption of this invention is 88 kWh / t, while the unit energy consumption of a traditional gas-fired kiln is 136 m³ natural gas / t. According to the energy conversion factor, the energy-saving efficiency of this invention reaches more than 35%.

[0028] Regarding product quality, the iron oxide red product prepared by this invention has an Fe2O3 content as high as 99.03%, significantly better than the 98.37% level of traditional gas-fired kilns. This is mainly due to the precise temperature control device of this invention. Temperature control accuracy test results show that this invention can control the temperature fluctuation within the kiln within an extremely narrow range of ±5℃, far superior to the ±28℃ control accuracy of traditional gas-fired kilns. This precise temperature control capability ensures the stability of the chemical reaction process and the consistency of the product.

[0029] In terms of environmental performance, this invention completely avoids the combustion process due to the use of electromagnetic heating, resulting in no detected NOx emissions in the exhaust gas. In contrast, traditional gas-fired kilns emit NOx at concentrations up to 180 mg / m³, posing a significant environmental pollution problem. This system produces no combustion exhaust gas, simplifies exhaust gas treatment, meets green production requirements, and solves the problems of high energy consumption, significant pollution, easy oxidation, and low temperature control precision of traditional rotary kilns, achieving efficient, energy-saving, and environmentally friendly preparation of iron oxide red.

[0030] These comparative data fully demonstrate the comprehensive advantages of this invention in terms of energy consumption, product quality, process control, and environmental performance, providing a more efficient, precise, and clean solution for iron oxide production.

[0031] In addition to the above embodiments, this utility model may have other implementation methods; all technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by this utility model.

Claims

1. A red iron oxide preparation system based on an electromagnetically heated rotary kiln, comprising a rotary kiln (3) and a raw material feeding device and a tail gas treatment device respectively connected to its inlet and outlet, characterized in that, The rotary kiln (3) is composed of a magnetic conductive layer (11), a stainless steel layer (10) and a heat insulation layer (9) connected sequentially from the inside to the outside. At least one set of electromagnetic induction coils (4) that generate electromagnetic induction with the magnetic conductive layer (11) when energized are arranged spirally on the outside of the kiln. There is a gap between the electromagnetic induction coils (4) and the outer wall of the kiln. A spiral guide plate (12a) is also spirally arranged on the inner wall of the magnetic conductive layer (11) so that the raw material inside is guided from the inlet to the outlet of the rotary kiln (3) along the spiral guide plate (12a) when the kiln rotates.

2. The iron oxide red preparation system according to claim 1, characterized in that, The electromagnetic induction coils (4) are arranged in four groups from the inlet to the outlet of the rotary kiln (3). The first group is the preheating section, the second and third groups are the reaction sections, and the fourth group is the heat preservation section. Each electromagnetic induction coil (4) is equipped with a high-temperature thermocouple.

3. The iron oxide red preparation system according to claim 1, characterized in that, The raw material feeding device includes a feeding bin (1) and a screw feeder (2) connected thereto. The end of the screw feeder (2) away from the feeding bin (1) is connected to the inlet of the rotary kiln (3).

4. The iron oxide red preparation system according to claim 3, characterized in that, The feed bin (1) has a volume of 3m³, and the screw feeder (2) has an inner diameter of 200mm and a pitch of 150mm.

5. The iron oxide red preparation system according to claim 1, characterized in that, The exhaust gas treatment device includes a bag filter (7) and an induced draft fan (8) connected thereto. The bag filter (7) is connected to the outlet of the rotary kiln (3).

6. The iron oxide red preparation system according to claim 1, characterized in that, The thermal insulation layer (9) is composed of a 50mm thick nano-aerogel felt layer and a 30mm thick aluminum silicate fiber blanket layer.

7. The iron oxide red preparation system according to claim 1, characterized in that, The rotary kiln (3) is connected to a drive system consisting of a 7.5kW variable frequency motor and a gear reducer with a speed ratio of 1:

35.

8. The iron oxide red preparation system according to claim 1, characterized in that, The electromagnetic induction coil (4) is made of copper tubing.

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