Rotary kiln with high electro-thermal conversion rate and reduced iron production method thereof

Abstract

The invention belongs to the field of reduced iron processing, and particularly relates to a rotary kiln with high electro-thermal conversion rate, which comprises a first kiln cylinder and a second kiln cylinder which are arranged above a bearing platform, the first kiln cylinder is driven by a first driving mechanism to rotate, and the second kiln cylinder is driven by a second driving mechanism to rotate; the first kiln cylinder and the second kiln cylinder are connected through a transfer section, and iron ore materials are conveyed in a channel where the first kiln cylinder, the second kiln cylinder and the transfer section are communicated. Through staged heating and non-contact electromagnetic heat transfer, efficient electric energy is used for converting high-temperature heat and conducting the high-temperature heat to iron ore and a reducing agent in a special high-temperature-resistant barrel body which basically rolls in a sealed mode, a high-temperature micro-positive-pressure environment is formed in the barrel body, and saturated reduction of saturated fixed carbon: C and carbon monoxide: CO on the iron ore is achieved; supply of high-quality raw materials for short-process steelmaking in areas rich in iron ore but free of coal resources is effectively achieved, and the problem that electric furnace steelmaking is limited by insufficient scrap steel amount is solved.

Description

Technical Field

[0001] The present invention relates to the field of reduced iron processing, and in particular to a rotary kiln with a high electric heat conversion rate and a reduced iron production method thereof. Background Art

[0002] Rotary kiln iron reduction is a direct reduction ironmaking method that uses a rotary kiln as a reactor to convert iron ore into iron through a solid-phase reduction reaction. The specific process is as follows: The rotary kiln is a continuously rotating device that serves as a reactor. Solid carbon (such as coal) is typically used as the reducing agent. The reaction takes place at temperatures between 950 and 1100°C. The thin layer of material inside the kiln creates a large free space, allowing airflow to escape freely. The high temperature at the kiln outlet facilitates the selective reduction and removal of elements and oxides with low gasification temperatures. However, due to the low reduction temperature, gangue in the ore remains in the product, preventing full carburization. The reduction results in oxygen loss, forming numerous micropores, giving the product a sponge-like microstructure, hence the name sponge iron.

[0003] Some areas are rich in iron ore but lack coal resources. When producing reduced iron, there is a lack of sufficient energy support, resulting in insufficient regional steel production. The traditional rotary kiln sponge iron production process is highly polluting and energy-intensive. The coal exothermic process produces a large amount of waste gas that pollutes the environment. The coal exothermic process also has the problem of insufficient heat utilization efficiency. Summary of the Invention

[0004] (1) Purpose of the invention In order to solve the technical problems existing in the background technology, the present invention proposes a rotary kiln with high electric heat conversion rate, which has the characteristics of high electric heat conversion rate and high temperature control precision.

[0005] (2) Technical solution To solve the above technical problems, the present invention provides a rotary kiln with a high electric heat conversion rate, comprising a first kiln drum and a second kiln drum arranged above a load-bearing platform, wherein the first kiln drum is controlled to rotate by a first driving mechanism, and the second kiln drum is controlled to rotate by a second driving mechanism; The first kiln drum and the second kiln drum are connected by a transfer section, and iron ore materials are transported in a channel connecting the three. The temperature measuring mechanism includes a sensor rack provided on the first kiln drum and the second kiln drum, the sensor rack being provided with a plurality of armored sensors connected to the network, and the armored sensors being provided with probes penetrating the inner cavities of the first kiln drum and the second kiln drum; The heating mechanism includes a first kiln drum heater sleeved on the outer circumference of the first kiln drum and a second kiln drum heater sleeved on the outer circumference of the second kiln drum, the first kiln drum heater and the second kiln drum heater are symmetrically arranged along the forward direction of the first kiln drum and the second kiln drum, respectively, to continuously heat the inner cavities of the first kiln drum and the second kiln drum; The separation mechanism comprises a first protective cover and a second protective cover which are sleeved on the outer sides of the first kiln drum and the second kiln drum, and the first protective cover and the second protective cover are used for separating the preheating section and the reduction section respectively.

[0006] Preferably, the first driving mechanism includes a first shaft frame installed below the first kiln drum, a rotatable first driving shaft is installed in the middle of the first shaft frame, the outer wall of the first driving shaft is provided with a first transmission wheel, and the first transmission wheel drives the first belt provided on the outer wall of the first kiln drum to rotate.

[0007] Preferably, the second driving mechanism includes a second shaft frame installed below the second kiln drum, a rotatable second driving shaft is installed in the middle of the second shaft frame, the outer wall of the second driving shaft is provided with a second transmission wheel, and the second transmission wheel drives the second belt provided on the outer wall of the second kiln drum to rotate.

[0008] Preferably, the first kiln drum and the second kiln drum are made of a metal material with high thermal conductivity, and the outer diameter of the first kiln drum is 860 mm and the inner diameter is 600 mm; The outer diameter of the second kiln tube is 1400 mm and the inner diameter is 1020 mm.

[0009] Preferably, the two first kiln drum heaters external to the first kiln drum are both 160KW electromagnetic heaters, and the length of the heating section is 3000mm; The ten second kiln drum heaters outside the second kiln drum are all 140KW electromagnetic heaters, and the length of the heating section is 8900mm.

[0010] Preferably, the first kiln drum heater and the second kiln drum heater are installed above the load-bearing platform through a support frame, the end surfaces of the first kiln drum heater and the second kiln drum heater facing the first kiln drum and the second kiln drum are arc-shaped heat-conducting end surfaces, and an air gap is left near the first kiln drum and the second kiln drum.

[0011] Preferably, the temperature measuring mechanism includes the sensor rack installed on the first kiln drum, and two groups of armored sensors connected to the wireless network are installed on the sensor rack. The lengths of the probes on the armored sensors that penetrate into the inner cavity of the first kiln drum are 1300 mm and 2635 mm respectively, and the distance between the two probes is 60 mm.

[0012] Preferably, the temperature measuring mechanism also includes a sensor rack installed on the second kiln drum, on which five groups of armored sensors connected to the wireless network are installed, and the lengths of the probes on the armored sensors that penetrate into the inner cavity of the first kiln drum are 1690mm, 3490mm, 5290mm, 7090mm and 8890mm respectively, and the distance between each two probes is 60mm.

[0013] Preferably, a hopper for adding the main machine is installed at the feed end of the first kiln drum and the middle position of the transfer section. The hopper has a built-in valve body for controlling opening and closing, and a spiral transmission mechanism is installed at the position connecting the first kiln drum and the transfer section.

[0014] The present invention also provides a method for producing reduced iron in a rotary kiln with a high electrothermal conversion rate, comprising the following steps: Step 1: crush the iron ore to a particle size of -mm, mix it with a reducing agent, and feed it into the first kiln drum, and continuously add materials through the hopper on the first kiln drum; Step 2: The first kiln drum is controlled to rotate by the first driving mechanism, and the first kiln drum heater in the preheating section of the first kiln drum is working, wherein the power of the first kiln drum heater at the front end is set to 30%, and the power of the first kiln drum heater at the rear end is set to 85%. The temperature inside the drum in the preheating section is monitored by the two probes and transmitted to the external control device through the wireless network connected to the armored sensor to assist in temperature control of the preheating section; Step 3: The second kiln drum is controlled to rotate by the second driving mechanism, and the first kiln drum heater in the reduction section of the second kiln drum is working, wherein the power of the two first kiln drum heaters at the front is set to 100%, the power of the six first kiln drum heaters in the middle is set to 85%, and the power of the first kiln drum heater at the rear is set to 70%. The temperature inside the drum in the preheating section is monitored by the five probes and transmitted to the external control device through the wireless network connected to the armored sensor, to assist in the distributed temperature control at the front, middle and rear of the reduction section; Step 4: introducing CO gas into the second kiln drum through the transfer section to maintain a slightly positive pressure environment in the reduction section of the second kiln drum; Step 5: The temperatures of the first kiln drum preheating section and the second kiln drum reduction section are distributedly monitored by the probes. The rotation speeds of the first drive mechanism and the second drive mechanism are controlled according to the temperatures at the corresponding positions to adjust the residence time of the iron ore.

[0015] The above-mentioned technical solution of the present invention has the following beneficial technical effects: through staged heating and non-contact electromagnetic heat transfer, high-temperature heat is converted by efficient electric energy and transferred to the iron ore and reducing agent in a special high-temperature resistant basically sealed rolling barrel. The barrel is in a high-temperature, slightly positive pressure environment, achieving saturated fixed carbon: C and carbon monoxide: CO to achieve saturated reduction of iron ore, effectively solving the problem of high-quality raw material supply for short-process steelmaking in areas with rich iron ore but no coal resources, and solving the problem of electric furnace steelmaking being constrained by insufficient scrap steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 It is a schematic structural diagram of the heating mechanism of the present invention; Figure 3 This is a schematic structural diagram of the first kiln drum of the present invention; Figure 4 This is a schematic structural diagram of the second kiln drum of the present invention; Figure 5 It is a schematic structural diagram of the temperature measuring mechanism of the present invention.

[0017] Reference numerals: 1. Load-bearing platform; 2. First kiln drum; 3. Transfer section; 4. Second kiln drum; 51. First shaft frame; 52. First drive shaft; 53. First transmission wheel; 54. First pulley; 61. Second shaft frame; 62. Second drive shaft; 63. Second transmission wheel; 64. Second pulley; 71. Sensor frame; 72. Armored sensor; 73. Probe; 81. First kiln drum heater; 82. Second kiln drum heater; 91. First protective cover; 92. Second protective cover. DETAILED DESCRIPTION

[0018] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0019] like Figure 1-5 As shown, the present invention proposes a rotary kiln with a high electric heat conversion rate, comprising a first kiln drum 2 and a second kiln drum 4 arranged above a load-bearing platform 1. The first kiln drum 2 is controlled to rotate by a first driving mechanism, and the second kiln drum 4 is controlled to rotate by a second driving mechanism. The first kiln drum 2 and the second kiln drum 4 are connected by a transfer section 3, and iron ore materials are transported in the channel connecting the three. The temperature measuring mechanism includes a sensor rack 71 provided on the first kiln drum 2 and the second kiln drum 4. The sensor rack 71 is provided with a plurality of armored sensors 72 connected to the network. The armored sensors 72 are provided with probes 73 penetrating into the inner cavities of the first kiln drum 2 and the second kiln drum 4. The heating mechanism includes a first kiln drum heater 81 sleeved on the outer periphery of the first kiln drum 2 and a second kiln drum heater 82 sleeved on the outer periphery of the second kiln drum 4. The first kiln drum heater 81 and the second kiln drum heater 82 are symmetrically arranged along the forward direction of the first kiln drum 2 and the second kiln drum 4, respectively, to continuously heat the inner cavities of the first kiln drum 2 and the second kiln drum 4. The separation mechanism includes a first protective cover 91 and a second protective cover 92 which are sleeved on the outside of the first kiln drum 2 and the second kiln drum 4, and are used to separate the preheating section and the reduction section respectively.

[0020] It should be noted that this application adopts a double kiln drum staged treatment. The first kiln drum 2 and the second kiln drum 4 are made of high thermal conductivity metal materials, which serve as the preheating section and the reduction section respectively. The staged design can optimize energy consumption. The preheating section only needs partial heating, and the reduction section is heated centrally, avoiding energy waste caused by overall high temperature. The outer diameter of the first kiln drum 2 is 860 mm, and the inner diameter is 600 mm. The two first kiln drum heaters 81 installed outside the first kiln drum 2 are both 160 kW electromagnetic heaters with a heating section length of 3000 mm, which are used for material preheating and initial reduction reaction. The outer diameter of the second kiln drum 4 is 1400 mm, and the inner diameter is 1020 mm. The ten second kiln drum heaters 82 outside the second kiln drum 4 are all 140KW electromagnetic heaters, and the heating section length is 8900 mm, which expands the reaction space to accommodate deep reduction at high temperatures greater than 1200°C.

[0021] In this embodiment, the first kiln drum heater 81 and the second kiln drum heater 82 are electromagnetic heaters, which are installed above the load-bearing platform 1 through a support frame. The end faces of the first kiln drum heater 81 and the second kiln drum heater 82 facing the first kiln drum 2 and the second kiln drum 4 are arc-shaped heat-conducting end faces, and an air gap is left near the first kiln drum 2 and the second kiln drum 4. Because an air gap is retained between the electromagnetic coils of the electromagnetic heaters and the barrels of the two kiln drums, indirect heat transfer is carried out through the eddy current effect of induction heating, avoiding the oxidation loss of resistive contact heating, achieving the advantages of ultra-high electric heat conversion rate and high temperature control accuracy while improving thermal efficiency. With the support of thermal insulation materials, the thermal efficiency is above 98%, which is 20-25% of the energy consumption of traditional rotary kilns and tunnel kilns.

[0022] It is understandable that the kiln body is made of high thermal conductivity metal material to ensure that heat is transferred to the material quickly and evenly, reducing local overheating or cold areas, and maintaining stable performance in high temperature environments. Combined with non-contact heating, it reduces mechanical wear on the kiln barrel and extends the life of the equipment.

[0023] As an example of the rotation of the first kiln drum 2: the first driving mechanism includes a first shaft frame 51 installed below the first kiln drum 2, a rotatable first driving shaft 52 is installed in the middle of the first shaft frame 51, the outer wall of the first driving shaft 52 is provided with a first transmission wheel 53, and the first transmission wheel 53 drives the first belt 54 provided on the outer wall of the first kiln drum 2 to rotate; the first driving shaft 52 is controlled by an external driving device to drive the rotation, driving the first transmission wheel 53 and the first belt 54 to transmit, thereby realizing the rotation of the first kiln drum 2.

[0024] Similarly, the second kiln drum 4 rotates in the same way. The second driving mechanism includes a second shaft frame 61 installed below the second kiln drum 4. A rotatable second driving shaft 62 is installed in the middle of the second shaft frame 61. The outer wall of the second driving shaft 62 is provided with a second transmission wheel 63. The second transmission wheel 63 drives the second belt 64 provided on the outer wall of the second kiln drum 4 to rotate.

[0025] Furthermore, the temperature measuring mechanism includes a sensor rack 71 installed on the first kiln drum 2, on which are installed two sets of armored sensors 72 connected to the wireless network. The lengths of the probes 73 on the armored sensors 72 that penetrate into the inner cavity of the first kiln drum 2 are 1300 mm and 2635 mm respectively, and the distance between the two probes 73 is 60 mm.

[0026] Two probes are set in the preheating section of the first kiln drum 2: 1300mm and 2635mm to monitor the temperature gradient at the feed end and the middle to prevent insufficient preheating or overheating.

[0027] The temperature measuring mechanism also includes a sensor rack 71 installed on the second kiln drum 4. Five groups of armored sensors 72 connected to the wireless network are installed on the sensor rack 71. The lengths of the probes 73 on the armored sensors 72 that penetrate into the inner cavity of the first kiln drum 2 are 1690mm, 3490mm, 5290mm, 7090mm and 8890mm respectively, and the distance between each two probes 73 is 60mm.

[0028] The reduction section of the second kiln drum 4 is equipped with five probes with a spacing of 1690-8890 mm to monitor the reduction reaction process in a distributed manner to ensure uniform temperature in different areas, such as high temperature at the front end to start the reaction, maintaining the reaction in the middle, and cooling the back end to prevent over-reduction.

[0029] It should be added that the armored sensor 72 connected to the wireless network can realize real-time dynamic control through wireless data transmission, for example, by adjusting the kiln drum speed to control the material residence time and match different reduction rate requirements.

[0030] Hoppers for adding the main machine are installed at the feed end of the first kiln drum 2 and the middle position of the transfer section 3. The hoppers have built-in valves for controlling opening and closing, and a spiral transmission mechanism is installed at the position connecting the first kiln drum 2 and the transfer section 3.

[0031] It can be understood that CO gas is injected into the transfer section to maintain a slightly positive pressure, which on the one hand inhibits the reoxidation of iron oxides, and on the other hand promotes the C+CO2→2CO reaction, forming a self-circulating reducing atmosphere and reducing the consumption of external reducing agents. The CO partial pressure control can adjust the reduction rate to adapt to different grades of ores.

[0032] A method for producing reduced iron in a rotary kiln with a high electrothermal conversion rate comprises the following steps: Step 1: crush the iron ore into a particle size of 1-5 mm, mix it with the reducing agent and feed it into the first kiln drum 2, and continuously add materials through the hopper on the first kiln drum 2; Step 2: The first kiln drum 2 is controlled by the first driving mechanism to rotate, and the first kiln drum heater 81 in the preheating section of the first kiln drum 2 is working. The power of the first kiln drum heater 81 at the front end is set to 30%, and the power of the first kiln drum heater 81 at the rear end is set to 85%. The temperature inside the drum in the preheating section is monitored by two probes 73 and transmitted to the external control device through the wireless network connected by the armored sensor 72 to assist in temperature control of the preheating section. Among them, the power of the first section of the preheating section is 30%, which prevents the cold material from being suddenly heated and causing thermal stress cracking, and the power of the second section is 85%, which gradually raises the temperature to 800-1000℃.

[0033] Step 3: The second kiln drum 4 is controlled to rotate by the second driving mechanism, and the first kiln drum heaters 81 in the reduction section of the second kiln drum 4 are working. The power of the two first kiln drum heaters 81 in the front is set to 100%, the power of the six first kiln drum heaters 81 in the middle is set to 85%, and the power of the first kiln drum heater 81 in the rear is set to 70%. The temperature inside the drum in the preheating section is monitored by five probes 73 and transmitted to the external control device through the wireless network connected by the armored sensor 72, to assist in the distributed temperature control before, during and after the reduction section. Among them, the front section of the reduction stage uses 100% power to quickly reach the reaction temperature, the middle section uses 85% to maintain the reaction kinetics, and the rear section uses 70% cooling stage to prevent sponge iron from sintering.

[0034] Step 4: The CO gas is fed into the second kiln drum 4 through the transfer section 3 to maintain a slightly positive pressure environment in the reduction section of the second kiln drum 4; Step 5: The temperatures of the preheating section of the first kiln drum 2 and the reduction section of the second kiln drum 4 are distributed and monitored by the probe 73. The rotation speeds of the first and second drive mechanisms are controlled according to the temperatures at the corresponding positions, and the residence time of the iron ore is adjusted.

[0035] It should be understood that the above-described specific embodiments of the present invention are merely illustrative or illustrative of the principles of the present invention and do not constitute limitations of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included within the scope of protection of the present invention. In addition, the appended claims are intended to cover all variations and modifications that fall within the scope and metes and bounds of the appended claims, or equivalents thereof.

Claims

1. A rotary kiln with high electric heat conversion efficiency, characterized in that: The kiln comprises a first kiln drum (2) and a second kiln drum (4) arranged above a load-bearing platform (1), wherein the first kiln drum (2) is controlled to rotate by a first driving mechanism, and the second kiln drum (4) is controlled to rotate by a second driving mechanism; The first kiln drum (2) and the second kiln drum (4) are connected via a transfer section (3), and iron ore materials are transported in a channel connecting the three. The temperature measuring mechanism comprises a sensor rack (71) arranged on the first kiln drum (2) and the second kiln drum (4), the sensor rack (71) being equipped with a plurality of armored sensors (72) connected to a network, and the armored sensors (72) being equipped with probes (73) penetrating into the inner cavities of the first kiln drum (2) and the second kiln drum (4); The heating mechanism comprises a first kiln drum heater (81) sleeved on the outer periphery of the first kiln drum (2) and a second kiln drum heater (82) sleeved on the outer periphery of the second kiln drum (4), wherein the first kiln drum heater (81) and the second kiln drum heater (82) are symmetrically arranged along the forward direction of the first kiln drum (2) and the second kiln drum (4), respectively, to continuously supply heat to the inner cavities of the first kiln drum (2) and the second kiln drum (4); The separation mechanism comprises a first protective cover (91) and a second protective cover (92) which are sleeved on the outside of the first kiln drum (2) and the second kiln drum (4), and are used to separate the preheating section and the reduction section respectively.

2. The rotary kiln with high electric heat conversion efficiency according to claim 1, characterized in that: The first driving mechanism comprises a first shaft frame (51) installed below the first kiln drum (2), a rotatable first driving shaft (52) being installed in the middle of the first shaft frame (51), a first transmission wheel (53) being sleeved on the outer wall of the first driving shaft (52), and the first transmission wheel (53) driving a first belt (54) sleeved on the outer wall of the first kiln drum (2) to rotate.

3. The rotary kiln with high electric heat conversion efficiency according to claim 1, characterized in that: The second driving mechanism comprises a second shaft frame (61) installed below the second kiln drum (4), a rotatable second driving shaft (62) is installed in the middle of the second shaft frame (61), a second transmission wheel (63) is sleeved on the outer wall of the second driving shaft (62), and the second transmission wheel (63) drives a second belt (64) sleeved on the outer wall of the second kiln drum (4) to rotate.

4. The rotary kiln with high electric heat conversion efficiency according to claim 1, characterized in that: The first kiln drum (2) and the second kiln drum (4) are made of a high thermal conductivity metal material; the outer diameter of the first kiln drum (2) is 860 mm and the inner diameter is 600 mm; The outer diameter of the second kiln drum (4) is 1400 mm and the inner diameter is 1020 mm.

5. The rotary kiln with high electric heat conversion efficiency according to claim 1, characterized in that: The two first kiln drum heaters (81) external to the first kiln drum (2) are both 160KW electromagnetic heaters, and the length of the heating section is 3000mm; The ten second kiln drum heaters (82) external to the second kiln drum (4) are all 140KW electromagnetic heaters, and the length of the heating section is 8900mm.

6. The rotary kiln with high electric heat conversion efficiency according to claim 1, characterized in that: The first kiln drum heater (81) and the second kiln drum heater (82) are installed above the load-bearing platform (1) through a support frame. The end surfaces of the first kiln drum heater (81) and the second kiln drum heater (82) facing the first kiln drum (2) and the second kiln drum (4) are arc-shaped heat-conducting end surfaces, and air gaps are left near the first kiln drum (2) and the second kiln drum (4).

7. The rotary kiln with high electric heat conversion efficiency according to claim 1, characterized in that: The temperature measuring mechanism comprises the sensor rack (71) mounted on the first kiln drum (2), the sensor rack (71) being mounted with two groups of armored sensors (72) connected to a wireless network, the probes (73) on the armored sensors (72) probing into the inner cavity of the first kiln drum (2) having lengths of 1300 mm and 2635 mm respectively, and the distance between the two probes (73) being 60 mm.

8. The rotary kiln with high electric heat conversion efficiency according to claim 1, characterized in that: The temperature measuring mechanism further comprises a sensor rack (71) mounted on the second kiln drum (4), wherein the sensor rack (71) is mounted with five groups of armored sensors (72) connected to a wireless network, wherein the lengths of the probes (73) on the armored sensors (72) that penetrate into the inner cavity of the first kiln drum (2) are 1690 mm, 3490 mm, 5290 mm, 7090 mm and 8890 mm respectively, and the distance between each two probes (73) is 60 mm.

9. The rotary kiln with high electric heat conversion efficiency according to claim 1, characterized in that: A hopper for adding a main machine is installed at the feed end of the first kiln drum (2) and the middle position of the transfer section (3). The hopper has a built-in valve body for controlling opening and closing, and a spiral transmission mechanism is installed at the position connecting the first kiln drum (2) and the transfer section (3).

10. A rotary kiln reduced iron production method with high electrothermal conversion efficiency according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: crush the iron ore into a particle size of 1-5 mm, mix it with a reducing agent, and feed it into the first kiln drum (2), and continuously add materials through the hopper on the first kiln drum (2); Step 2: The first kiln drum (2) is controlled to rotate by the first driving mechanism, and the first kiln drum heater (81) in the preheating section of the first kiln drum (2) works, wherein the power of the first kiln drum heater (81) at the front end is set to 30%, and the power of the first kiln drum heater (81) at the rear end is set to 85%. The temperature inside the drum in the preheating section is monitored by the two probes (73) and transmitted to the external control device through the wireless network connected to the armored sensor (72), so as to assist in temperature control of the preheating section. Step 3: The second kiln drum (4) is controlled to rotate by the second driving mechanism, and the first kiln drum heater (81) in the reduction section of the second kiln drum (4) works, wherein the power of the two first kiln drum heaters (81) in the front is set to 100%, the power of the six first kiln drum heaters (81) in the middle is set to 85%, and the power of the first kiln drum heater (81) in the rear is set to 70%. The temperature inside the drum in the preheating section is monitored by the five probes (73) and transmitted to the external control device through the wireless network connected to the armored sensor (72), so as to assist the distributed temperature control before, during and after the reduction section; Step 4: The CO gas is fed into the second kiln drum (4) through the transfer section (3), and a slightly positive pressure environment is maintained in the reduction section of the second kiln drum (4); Step 5: The temperatures of the preheating section of the first kiln drum (2) and the reduction section of the second kiln drum (4) are distributedly monitored by the probe (73), and the rotation speeds of the first drive mechanism and the second drive mechanism are controlled according to the temperatures at the corresponding positions to adjust the residence time of the iron ore.

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