A ring kiln for direct reduction of iron

Abstract

The present invention discloses a ring kiln for direct reduction of iron, comprising: a preheating section, a high temperature section, a cooling section and a loading and unloading area; the preheating section comprises: a flue gas extraction section, a hot air preheating section and a bottom preheating section; the high temperature section comprises: a double-sided heating section and an upper heating section; the cooling section comprises: a bottom plate hot air extraction section and an air cooling section. The device of the present invention has the characteristics of large output, small footprint, small investment ratio, reduced energy consumption, high degree of automation, simple operation, etc. It can be applied to the deep reduction of high-grade iron ore DRI products, and can also be suitable for the slag-iron separation and reduction of various refractory iron ores, composite ores and iron-containing solid wastes and other raw materials. A tankless, static, wide-end-face, rotary ring reduction kiln and its main process wind structure are developed, which are particularly suitable for the deep reduction of various high-grade iron ore powders and various refractory iron ores, composite ores, iron-containing solid wastes and the slag-iron separation and reduction and the roasting and calcining of other materials. Improved iron reduction kiln.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgical kilns, in particular to an annular kiln for directly reducing iron. Background Art

[0002] The tunnel kiln direct reduction iron process has a good deep reduction function, but due to its large footprint, high labor intensity, low production capacity (a single tunnel kiln generally produces 10,000 to 30,000 tons), low degree of automation, and high investment ratio, it has not been widely promoted and applied in recent years, and it is even more impossible to achieve slag iron separation and reduction, and is applied to slag iron separation and reduction of various refractory iron ores and composite ores. my country is a region rich in refractory iron ore resources, which account for more than 98% of the total iron ore resources. China has huge refractory iron ore resources, which cannot be well utilized and developed.

[0003] In the prior art, some people have introduced foreign coal-based rotary hearth furnace equipment technology and process technology into my country. The rotary hearth furnace has the characteristics of high heating temperature and fast running speed. However, due to some unreasonable aspects of material distribution, heating method, kiln structure and process technology, the reduced materials are severely oxidized, the ferrous oxide content in DRI is very high, and the product reduction rate is low, which can never reach 80%. Therefore, the rotary hearth furnace device can only be used for the dezincification or zinc reduction of zinc-containing dust and zinc-containing dust mud in blast furnaces, and cannot be used for the deep reduction of direct reduced iron, let alone the slag iron separation and reduction of various difficult-to-select iron ores, composite ores and iron-containing solid wastes.

[0004] After searching, the patent with application number 201922101342.3 discloses a double-sided heating rotary hearth furnace. The kiln body is provided with a preheating section, a high-temperature reduction section and a cooling section in sequence along its circumferential direction. The high-temperature reduction section includes a high-temperature reduction front section, a middle section and a rear section. A plurality of lower burners are arranged on the front kiln wall, a plurality of upper burners and a lower burner are arranged on the middle kiln wall, and a plurality of upper burners are arranged on the rear kiln wall. The material bearing mechanism includes a refractory layer, a material receiving silicon carbide plate and a material layer. A lower heating chamber matched with the lower burner is arranged between the material receiving silicon carbide plate and the refractory layer, and the lower heating chamber is connected to the hot air branch of the refractory layer. This invention allows both sides of the material layer to be heated and flame-heated, so that the material layer can quickly reach a temperature above 880°C, realizing and meeting the basic and fundamental requirements of carbon-based reduction metallurgy theory and hydrogen-based reduction metallurgy theory; the hot air pipeline not only reduces the heat dissipation and investment of metal pipes outside the furnace, but also makes full use of the refractory material of the kiln wall, increases the temperature of the kiln wall and increases the amount of hot air in the kiln, thereby realizing the comprehensive utilization of waste heat.

[0005] This solution has the above-mentioned problems that it cannot completely meet the deep reduction of direct reduced iron, the slag iron separation reduction of various difficult-to-select iron ores and composite ores, the simultaneous heating of the reduced material and the bottom of the U-shaped silicon carbide pool, and the uniformity and thoroughness of the heating. There are some problems with its heating method. Therefore, we need to propose a ring kiln for direct reduced iron. Summary of the invention

[0006] The purpose of the present invention is to provide an annular kiln for direct reduction of iron, which is optimized and improved by combining the characteristics of a tunnel kiln and a rotary hearth furnace. In addition to the advantages of deep reduction of a tunnel kiln, it also has the advantages of large output, small footprint, small investment ratio, reduced energy consumption, high degree of automation, simple operation, etc. In addition to being able to apply high-grade iron ore to deep reduction of DRI products, it is also very suitable for slag-iron separation and reduction of various refractory iron ores, composite ores and iron-containing solid wastes. A reduction tank container is no longer used, and a tankless, static, wide-end-face, rotary annular reduction kiln is developed. The improved iron reduction kiln is suitable for deep reduction of various high-grade iron ore powders and various refractory iron ores, iron-containing solid wastes, slag-iron separation and reduction, and roasting and calcining of other materials. It has a wide range of applications to solve the problems raised in the above-mentioned background technology.

[0007] In order to achieve the above-mentioned purpose, the present invention provides the following technical solutions: a ring-shaped kiln for direct reduction iron, comprising: a preheating section, a high-temperature section, a cooling section and a loading and unloading area; the preheating section comprises: a smoke extraction section, a hot air preheating section and a bottom preheating section; the high-temperature section comprises: a double-sided heating section and an upper heating section; the cooling section comprises: a bottom plate hot air extraction section and an air cooling section; the length of the preheating section is shorter than the length of the high-temperature section and the cooling section; the unfolded length of the preheating section is 10 to 20 meters, accounting for 10 to 15% of the total unfolded length of the ring-shaped kiln; the unfolded length of the high-temperature section is 80 to 100 meters, accounting for 45 to 55% of the total unfolded length of the ring-shaped kiln; the unfolded length of the cooling section is 40 to 60 meters, accounting for 30 to 45% of the total unfolded length of the ring-shaped kiln;

[0008] It also includes: a concrete foundation, and an annular kiln body surrounded by a kiln roof and a kiln wall; a rotating chassis is installed inside the annular kiln body for rotation; a driving mechanism for driving the rotating chassis to rotate is installed between the annular kiln body and the concrete foundation; a material pool bracket is installed on the rotating chassis; a U-shaped silicon carbide material pool is arranged on the material pool bracket; the reduced material is contained inside the U-shaped silicon carbide material pool; a plurality of kiln wall smoke exhaust ports, a plurality of kiln wall hot air inlets and a plurality of kiln wall hot air outlets are opened on the kiln wall at the positions of the preheating section, the high temperature section and the cooling section; an upper row of main burners is arranged in the high temperature section, and a lower row of auxiliary burners are arranged in the preheating section and the high temperature section, and the lower row of auxiliary burners are located below the U-shaped silicon carbide material pool; the upper row of main burners is located above the U-shaped silicon carbide material pool; a hot air main pipe is installed on the kiln roof; one end of the hot air main pipe is connected to a hot air branch pipe located in the hot air preheating section;

[0009] The upper row of main burners is only distributed in the double-sided heating section of the high-temperature section, and the lower row of auxiliary burners is distributed in the bottom preheating section of the preheating section and the entire high-temperature section; the upper row of main burners heats the upper part of the U-shaped silicon carbide pool only in the double-sided heating section of the high-temperature section, and the upper row of main burners and the lower row of auxiliary burners are arranged in a "two" shape, and the length of the upper row of main burners is less than the length of the lower row of auxiliary burners, ensuring that the reduced materials in the U-shaped silicon carbide pool are evenly heated and the slag-iron separation reduction is continuously and stably achieved;

[0010] The kiln top is equipped with an air curtain branch pipe located in the hot air extraction section of the bottom plate and a cold air pipe at the kiln tail located in the air cooling section; the lower end of the cold air pipe at the kiln tail is connected with an inclined cold air nozzle at the kiln tail; the lower end of the air curtain branch pipe is connected with an air curtain nozzle; the hot air outlet in the kiln wall is connected with the hot air branch pipe in the kiln wall; one end of the hot air branch pipe in the kiln wall is connected with an induced draft fan air inlet pipe; a high-temperature induced draft fan is connected between the induced draft fan air inlet pipe and the other end of the hot air main pipe.

[0011] Preferably, the driving mechanism includes a supporting roller assembly and a hydraulic drive motor assembly fixed on a concrete foundation; the lower end side of the rotating chassis is connected to the outer toothed belt of the rotating disc; the outer toothed belt of the rotating disc is located on the supporting roller assembly; the large gear on the hydraulic drive motor assembly is coupled to the outer toothed belt of the rotating disc.

[0012] Preferably, the width of the U-shaped silicon carbide material pool is set to 4000-6000 mm; the thickness of the silicon carbide plate of the U-shaped silicon carbide material pool is 35-45 mm, which is resistant to high temperature, and the total height of the U-shaped silicon carbide material pool is 200-250 mm, which is assembled from multiple fan-shaped silicon carbide plates with snap fasteners.

[0013] Preferably, the net height of the material pool support is 220-320 mm, and the thickness of the material layer of the reduced material is 160-180 mm.

[0014] Preferably, multiple hot air inlets in the kiln wall and multiple lower row auxiliary burners are added on both sides of the kiln wall of the hot air preheating section and the bottom preheating section in the preheating section to perform rapid flame muffle preheating and heating on the bottom of the U-shaped silicon carbide pool;

[0015] The lower row of auxiliary burners introduces hot air generated by the cooling section through multiple hot air inlets in the kiln wall in the hot air preheating section of the preheating section, and quickly preheats and heats the bottom of the U-shaped silicon carbide material pool in a flame-muffled manner; in the bottom preheating section of the preheating section, the multiple lower row of auxiliary burners quickly preheats and heats the bottom of the U-shaped silicon carbide material pool in advance in a flame-muffled manner; in the entire high-temperature section, the multiple lower row of auxiliary burners quickly heat and keep the bottom of the U-shaped silicon carbide material pool in advance in a flame-muffled manner.

[0016] Preferably, a plurality of upper main burners and a plurality of lower auxiliary burners are installed on both sides of the kiln wall of the double-sided heating section in the high-temperature section to heat the reduced material in the U-shaped silicon carbide material pool from top to bottom, so that the reduced material is maintained at 1200-1300°C.

[0017] Preferably, the diameter of the rotating chassis is set to 40-80m; the supporting wheel assembly is supported at the lower end of the rotating chassis; the supporting wheel assembly is composed of a plurality of tugboats distributed in concentric circles and with uniform elevations; the rotating chassis performs concentric intermittent circular motion or concentric uniform circular motion.

[0018] Preferably, the rotating chassis is configured as a steel structure, and the upper and middle parts of the rotating chassis are inlaid with refractory materials with a thickness of 1200 to 1500 mm.

[0019] The duration of the reduced material in the preheating section is 1 to 1.5 hours, the reduction time in the high temperature section is 6 to 10 hours, and the duration in the cooling section is 4 to 5 hours.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention combines the characteristics of a tunnel kiln and a rotary hearth furnace, and is optimized and improved. In addition to having the advantages of deep reduction of a tunnel kiln, the present invention also has the advantages of large output, small footprint, small investment ratio, reduced energy consumption, high degree of automation, simple operation, etc. In addition to being applicable to high-grade iron ore deep reduction DRI products, the present invention is also very suitable for slag-iron separation and reduction of various refractory iron ores, composite ores and iron-containing solid wastes. A reduction tank container is no longer used, and a tankless, static, wide-end-face, rotary annular reduction kiln is developed. The improved iron reduction kiln is suitable for deep reduction of various high-grade iron ore powders and various refractory iron ores, iron-containing solid wastes, slag-iron separation and reduction, and roasting and calcining of other materials, and has a wide range of applications.

[0022] The annular kiln for direct iron reduction of the present invention is also suitable for pot-type iron reduction and calcination and roasting of other materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the distribution of three sections and four zones of the overall annular kiln device of the present invention from a top view;

[0024] Figure 2 It is a side unfolded view of the overall structure of the annular kiln of the present invention;

[0025] Figure 3 This is a schematic diagram of the end face in the AA′ direction of the present invention;

[0026] Figure 4 This is a schematic diagram of the end face in the BB′ direction of the present invention;

[0027] Figure 5 This is a schematic diagram of the end face in the CC′ direction of the present invention;

[0028] Figure 6 This is a schematic diagram of the end face in the DD′ direction of the present invention;

[0029] Figure 7 This is a schematic diagram of the end face in the EE′ direction of the present invention;

[0030] Figure 8 This is a schematic diagram of the end face in the FF′ direction of the present invention;

[0031] Fig. 9 It is a schematic diagram of the end face of the rotating chassis of the present invention.

[0032] In the figure: 1. kiln roof; 2. smoke exhaust port in kiln wall; 3. kiln wall; 4. U-shaped silicon carbide material pool; 5. material pool bracket; 6. hot air inlet in kiln wall; 7. supporting wheel assembly; 8. hot air branch pipe; 9. hot air main pipe; 10. lower row auxiliary burners; 11. upper row main burners; 12. hot air outlet in kiln wall; 13. hot air branch pipe in kiln wall; 14. induced draft fan air inlet pipe; 15. high-temperature induced draft fan; 16. cold air duct at kiln tail; 17. air curtain branch pipe; 18. cold air nozzle at kiln tail; 19. concrete foundation; 20. reduced material; 21. rotating chassis; 22. hydraulic drive motor assembly; 23. air curtain nozzle; 24. toothed belt on the outer side of rotating disc. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] See also Figures 1 to 9 The present invention provides a technical solution: a ring kiln for direct reduction of iron, comprising: a preheating section, a high temperature section, a cooling section and a loading and unloading area; the preheating section comprises: a smoke extraction section, a hot air preheating section and a bottom preheating section; the high temperature section comprises: a double-sided heating section and an upper heating section, and the cooling section comprises a bottom plate hot air extraction section and an air cooling section. The length of the preheating section is shorter than that of the high temperature section and the cooling section. The unfolded length of the preheating section is 10 to 20 meters, accounting for 10 to 15% of the total unfolded length of the ring kiln; the unfolded length of the high temperature section is 80 to 100 meters, accounting for 45 to 55% of the total unfolded length of the ring kiln; the unfolded length of the cooling section is 40 to 60 meters, accounting for 30 to 45% of the total unfolded length of the ring kiln;

[0035] An annular kiln is composed of four areas: a preheating section, a high-temperature section, a cooling section and a loading and unloading area. The reduced material 20 after reduction in the cooling section is quickly unloaded through the loading and unloading area and quickly loaded with new reduced material 20, and then enters the preheating section again, forming a closed cycle motion, and performing a cyclical reduction cycle motion over and over again, which has the characteristics of high degree of automation, large output, energy saving and emission reduction, etc.

[0036] The kiln also includes: a concrete foundation 19 and an annular kiln body surrounded by a kiln roof 1 and a kiln wall 3, a rotating chassis 21 is rotatably installed inside the annular kiln body, a driving mechanism for driving the rotating chassis 21 to rotate is installed between the annular kiln body and the concrete foundation 19, a material pool bracket 5 is installed on the rotating chassis 21, a U-shaped silicon carbide material pool 4 is arranged on the material pool bracket 5, and the U-shaped silicon carbide material pool 4 contains reduced materials 20, and the kiln wall 3 is located in the preheating section, the high temperature section and the cooling section. The cooling section is provided with a plurality of smoke exhaust ports 2 in the kiln wall, a plurality of hot air inlets 6 in the kiln wall and a plurality of hot air outlets 12 in the kiln wall, the high temperature section is provided with an upper row of main burners 11, the preheating section and the high temperature section are provided with a lower row of auxiliary burners 10, the lower row of auxiliary burners 10 are located below the U-shaped silicon carbide material pool 4, the upper row of main burners 11 are located above the U-shaped silicon carbide material pool 4, a hot air main pipe 9 is installed on the kiln top 1, and one end of the hot air main pipe 9 is connected to a hot air branch pipe 8 located in the hot air preheating section;

[0037] The upper row of main burners 11 are only distributed in the double-sided heating section of the high-temperature section, and the lower row of auxiliary burners 10 are distributed in the bottom preheating section of the preheating section and the entire high-temperature section; the upper row of main burners 11 heats the upper part of the U-shaped silicon carbide pool 4 only in the double-sided heating section of the high-temperature section, and the arrangement of the upper row of main burners 11 and the lower row of auxiliary burners 10 is in a "two" shape, and the length of the upper row of main burners 11 is less than the length of the lower row of auxiliary burners 10, ensuring that the reduced material 20 in the U-shaped silicon carbide pool 4 is evenly heated and the slag-iron separation reduction is continuously and stably realized;

[0038] The kiln roof 1 is provided with an air curtain branch pipe 17 located in the hot air extraction section of the bottom plate and a kiln tail cold air pipe 16 located in the air cooling section. The lower end of the kiln tail cold air pipe 16 is connected with an inclined kiln tail cold air nozzle 18, the lower end of the air curtain branch pipe 17 is connected with an air curtain nozzle 23, the hot air outlet 12 in the kiln wall is connected with the hot air branch pipe 13 in the kiln wall, one end of the hot air branch pipe 13 in the kiln wall is connected with an induced draft fan air inlet pipe 14, and a high-temperature induced draft fan 15 is connected between the induced draft fan air inlet pipe 14 and the other end of the hot air main pipe 9.

[0039] After the U-shaped silicon carbide pool 4 and the reduced material 20 enter the cooling section, after a certain distance and time, they are deeply reduced. Then, the high-temperature induced draft fan 15 can be used to blow the waste flue gas or cold air from the flue gas extraction section onto the cover layer of the reduced material 20 through the wind curtain branch pipe 17 and the wind curtain nozzle 23. At the same time, part of the cold air is blown obliquely into the cover layer of the reduced material 20 through the kiln tail cold air pipe 16 and the kiln tail cold air nozzle 18, thereby cooling the reduced material 20 and the U-shaped silicon carbide material. The pool 4, the material pool support 5 and the rotating chassis 21 are directly cooled. At the same time, a large amount of hot air with a sensible heat of 750-900°C can be obtained, which can be drawn in equal amounts through the hot air outlet 12 in the kiln wall, the hot air branch pipe 13 in the kiln wall, the induced draft fan air inlet pipe 14, the high-temperature induced draft fan 15 and the hot air main pipe 9, and then through the hot air branch pipe 8 and the hot air inlet 6 in the kiln wall, and then injected into the hot air preheating section to preheat the U-shaped silicon carbide material pool 4 and the reduced material 20.

[0040] The preheating air in the preheating section, combined with the combustion hot air in the high-temperature section (high-temperature hot air formed by the combustion of gas and combustion-supporting air) and the cooling air in the cooling section and other process air, are reasonably arranged and utilized to achieve comprehensive utilization of waste heat and energy conservation and emission reduction.

[0041] The driving mechanism includes a supporting roller assembly 7 and a hydraulic drive motor assembly 22 fixed on a concrete foundation 19. The hydraulic drive motor assembly 22 is provided with 2 to 6 parts. The lower end side of the rotating chassis 21 is connected to the outer toothed belt 24 of the rotating disc. The outer toothed belt 24 of the rotating disc is located on the supporting roller assembly 7. The large gear on the hydraulic drive motor assembly 22 is coupled with the outer toothed belt 24 of the rotating disc to ensure that the rotating chassis 21 runs smoothly and synchronously.

[0042] The width of the U-shaped silicon carbide pool 4 is set to 4000-6000 mm, the thickness of the silicon carbide plate of the U-shaped silicon carbide pool 4 is 35-45 mm, and it is resistant to high temperatures. The total height of the U-shaped silicon carbide pool 4 is 200-250 mm, and it is assembled from multiple fan-shaped silicon carbide plates with snap fasteners.

[0043] The net height of the material pool support 5 is 220-320 mm, which fully guarantees the combustion space of the flame of the lower auxiliary burner 10, so that it can burn fully and heat the bottom of the U-shaped silicon carbide material pool 4 with flame insulation. The thickness of the material layer of the reduced material 20 is 160-180 mm. While ensuring the deep reduction of the material and the separation and reduction of slag and iron, the charging amount can be increased by 5 times compared with the rotary hearth furnace method.

[0044] The annual ore processing capacity of a single kiln device in the present invention can reach 100,000 to 200,000 tons, and a reduction rate of 93% to 96% can be achieved. In addition, various refractory iron ores can be separated and reduced by slag. The reduced metal powder after grinding has a grade of TFe≥90%, a reduction rate≥93%, and a recovery rate≥93%, which are "three 90s" product indicators, or even the highest product indicator of "four 90s" (plus the indicator of metallic iron MFe≥90%). It can even be applied to an industrial engineering project for separation and reduction of slag and iron from a nickel-containing limonite composite ore with a length of 128m, and a large number of granular iron products as large as peanuts, beans, and rice grains can be separated out through reduction production, fully realizing the product indicators of "four 90s".

[0045] Multiple hot air inlets 6 and multiple lower auxiliary burners 10 are added on both sides of the kiln wall 3 of the hot air preheating section in the preheating section and the bottom preheating section, which are used to quickly preheat and heat the bottom of the U-shaped silicon carbide pool 4 in a flame-muffled manner, so that the reduced material 20 is quickly raised to above 900°C, and the reducing agent in the reduced material 20 is quickly decomposed into CO and H2 reducing gases, and the oxygen element in the iron oxide of the iron ore is subjected to a violent reaction to reach a temperature of more than 880°C, and a direct and indirect reduction reaction is carried out, so that the reducing agent is not slowly pyrolyzed, so that CO and H2 reducing gases are volatilized, and because the iron oxide ore does not reach a temperature of more than 880°C for a violent reaction, it becomes a combustible gas and does not play the role of a reducing agent, thereby causing a waste of volatiles in the reducing agent; this scheme makes full use of the characteristic that the reduction rate of H2 in the reduced material 20 at 880°C is 5 times that of CO, and artificially sets and promotes it to accelerate the reduction reaction, so that it can reach and meet the requirements of the double-base reduction metallurgy theory as much as possible.

[0046] In the hot air preheating section of the preheating section, the lower row of auxiliary burners 10 introduces the hot air generated by the cooling section through multiple hot air inlets 6 in the kiln wall, and quickly preheats and heats the bottom of the U-shaped silicon carbide material pool 4 in a flame-muffled manner; in the bottom preheating section of the preheating section, the bottom of the U-shaped silicon carbide material pool 4 is quickly preheated and heated in advance by multiple lower row auxiliary burners 10; in the entire high-temperature section, the bottom of the U-shaped silicon carbide material pool 4 is quickly preheated and heated in advance by multiple lower row auxiliary burners 10.

[0047] A plurality of upper main burners 11 and a plurality of lower auxiliary burners 10 are installed on both sides of the kiln wall 3 of the double-sided heating section in the high-temperature section, so as to heat the reduced material 20 in the U-shaped silicon carbide material pool 4 on both the upper and lower sides, so that the reduced material 20 is maintained at the reduction temperature of 1200-1300°C required by the process and the temperature required for slag iron reduction, so that the reduced material 20 undergoes a rapid reduction reaction.

[0048] The diameter of the rotating chassis 21 is set to 40-80m, and the supporting wheel assembly 7 is supported at the lower end of the rotating chassis 21. The supporting wheel assembly 7 is composed of a plurality of tugboats distributed in concentric circles and with uniform elevations. The rotating chassis 21 performs concentric intermittent circular motion or concentric uniform circular motion.

[0049] The rotating chassis 21 is configured as a steel structure, and the upper and middle parts of the rotating chassis 21 are inlaid with 1200-1500 mm thick refractory materials for heat insulation, heat preservation and material support.

[0050] The duration of the reduced material 20 in the preheating section is 1 to 1.5 hours, the reduction time in the high temperature section is 6 to 10 hours, and the duration in the cooling section is 4 to 5 hours.

[0051] The annular kiln of this scheme can be used for deep reduction and slag-iron separation reduction of high-grade iron ore and various refractory iron ores, composite ores, iron-containing solid waste and other materials. It is also suitable for the reduction, roasting and calcination of other materials.

[0052] During use, in order to save energy and reduce emissions, the hot air with a sensible heat of 750-900°C artificially extracted from the cooling section is pumped into the hot air preheating section through the hot air main pipe 9 and the hot air branch pipe 8 from the hot air inlets 6 in the kiln wall, that is, between the material pool brackets 5 at the bottom of the U-shaped silicon carbide material pool 4, to preheat the reduced material 20 in the U-shaped silicon carbide material pool 4. Figure 4 ;

[0053] The waste flue gas from the high temperature section and the flue gas extraction section is extracted by the main exhaust fan of the kiln through multiple exhaust ports 2 in the kiln wall. The waste flue gas is discharged after being treated. Figure 3 ;

[0054] When the U-shaped silicon carbide pool 4 runs to the upper heating section and the reduced material 20 is about to be reduced, the upper row of main burners 11 stop heating, and only the lower row of auxiliary burners 10 continue to heat the bottom of the U-shaped silicon carbide pool 4. Figure 7 ;

[0055] After the U-shaped silicon carbide pool 4 and the reduced material 20 enter the cooling section, after a certain distance and time of static heat preservation and reduction, the high-temperature induced draft fan 15 can be used to blow the waste flue gas or cold air from the flue gas extraction section onto the cover layer of the reduced material 20 through the wind curtain branch pipe 17 and the wind curtain nozzle 23. At the same time, part of the cold air is obliquely blown into the cover layer of the reduced material 20 through the kiln tail cold air pipe 16 and the kiln tail cold air nozzle 18, thereby directly cooling the reduced material 20, the U-shaped silicon carbide pool 4, the pool support 5 and the rotating chassis 21;

[0056] At the same time, a large amount of hot air with a sensible heat of 750-900°C will be obtained, which can be extracted in equal amounts through the hot air outlet 12 in the kiln wall, the hot air branch pipe 13 in the kiln wall, the induced draft fan air inlet pipe 14, the high-temperature induced draft fan 15 and the hot air main pipe 9, and then through the hot air branch pipe 8 and the hot air inlet 6 in the kiln wall, and then injected into the hot air preheating section to preheat the U-shaped silicon carbide material pool 4 and the reduced material 20.

[0057] In summary, the present invention combines the characteristics of tunnel kilns and rotary hearth furnaces, and is optimized and improved. In addition to the advantages of deep reduction of tunnel kilns, it also has the advantages of large output, small footprint, small investment ratio, reduced energy consumption, high degree of automation, simple operation, etc. In addition to being able to apply high-grade iron ore deep reduction DRI products, it is also very suitable for slag-iron separation and reduction of various difficult-to-select iron ores, composite ores and iron-containing solid wastes. Reduction tank containers are no longer used, and a tankless, static, wide-end-face, rotary annular reduction kiln is developed. It is suitable for deep reduction of various high-grade iron ore powders and various difficult-to-select iron ores, iron-containing solid wastes, slag-iron separation and reduction, and roasting and calcining of other materials. Improved iron reduction kiln, which has a wide range of applications.

[0058] The annular kiln for direct iron reduction of the present invention is also suitable for pot-type iron reduction and calcination and roasting of other materials.

[0059] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A ring kiln for direct reduction of iron, comprising: Preheating section, high temperature section, cooling section and loading and unloading area, characterized in that: the preheating section includes: smoke extraction section, hot air preheating section and bottom preheating section; the high temperature section includes: double-sided heating section and upper heating section; the cooling section includes: bottom plate hot air extraction section and air cooling section; the length of the preheating section is less than the length of the high temperature section and the cooling section, the unfolded length of the preheating section is 10-20m, accounting for 10-15% of the total unfolded length of the annular kiln; the unfolded length of the high temperature section is 80-100m, accounting for 45-55% of the total unfolded length of the annular kiln; the unfolded length of the cooling section is 40-60m, accounting for 30-45% of the total unfolded length of the annular kiln; It also includes: a concrete foundation (19) and an annular kiln body surrounded by a kiln top (1) and a kiln wall (3); a rotating chassis (21) is rotatably installed inside the annular kiln body; and a driving mechanism for driving the rotating chassis (21) to rotate is installed between the annular kiln body and the concrete foundation (19); The driving mechanism comprises a supporting wheel assembly (7) and a hydraulic drive motor assembly (22) fixed on a concrete foundation (19); the lower end side of the rotating chassis (21) is connected to an outer toothed belt (24) of a rotating disk; the outer toothed belt (24) of the rotating disk is located on the supporting wheel assembly (7); the large gear on the hydraulic drive motor assembly (22) is coupled to the outer toothed belt (24) of the rotating disk; A material pool bracket (5) is installed on the rotating chassis (21), and a U-shaped silicon carbide material pool (4) is arranged on the material pool bracket (5); the width of the U-shaped silicon carbide material pool (4) is set to 4000-6000 mm; the thickness of the silicon carbide plate of the U-shaped silicon carbide material pool (4) is 35-45 mm, and the total height of the high-temperature resistant U-shaped silicon carbide material pool (4) is 200-250 mm, and is assembled from a plurality of fan-shaped silicon carbide plates with snap fasteners; The U-shaped silicon carbide material pool (4) contains reduced material (20); the kiln wall (3) is provided with a plurality of kiln wall smoke exhaust ports (2), a plurality of kiln wall hot air inlets (6) and a plurality of kiln wall hot air outlets (12) at positions in the preheating section, the high temperature section and the cooling section; the high temperature section is provided with an upper row of main burners (11), the preheating section and the high temperature section are provided with a lower row of auxiliary burners (10), and the lower row of auxiliary burners (10) are located below the U-shaped silicon carbide material pool (4); the upper row of main burners (11) are located above the U-shaped silicon carbide material pool (4); a hot air main pipe (9) is installed on the kiln top (1); one end of the hot air main pipe (9) is connected to a hot air branch pipe (8) located in the hot air preheating section; The upper row of main burners (11) are only distributed in the double-sided heating section of the high-temperature section, and the lower row of auxiliary burners (10) are distributed in the bottom preheating section of the preheating section and the entire high-temperature section; the upper row of main burners (11) heats the upper part of the U-shaped silicon carbide pool (4) only in the double-sided heating section of the high-temperature section, the upper row of main burners (11) and the lower row of auxiliary burners (10) are arranged in a "two" shape, and the length of the upper row of main burners (11) is shorter than the length of the lower row of auxiliary burners (10), so as to ensure that the reduced material (20) in the U-shaped silicon carbide pool (4) is evenly heated and the slag-iron separation reduction is continuously and stably achieved; The kiln top (1) is provided with an air curtain branch pipe (17) located in the hot air extraction section of the bottom plate and a kiln tail cold air pipe (16) located in the air cooling section; the lower end of the kiln tail cold air pipe (16) is connected to an inclined kiln tail cold air nozzle (18), and the lower end of the air curtain branch pipe (17) is connected to an air curtain nozzle (23); the hot air outlet (12) in the kiln wall is connected to the hot air branch pipe (13) in the kiln wall; one end of the hot air branch pipe (13) in the kiln wall is connected to an induced draft fan air inlet pipe (14); a high-temperature induced draft fan (15) is connected between the induced draft fan air inlet pipe (14) and the other end of the hot air main pipe (9).

2. The annular kiln for direct reduced iron according to claim 1, characterized in that: The net height of the material pool support (5) is 220-320 mm; the thickness of the material layer of the reduced material (20) is 160-180 mm.

3. The annular kiln for direct reduced iron according to claim 1, characterized in that: A plurality of hot air inlets (6) and a plurality of lower row auxiliary burners (10) are added to both sides of the kiln wall (3) of the hot air preheating section and the bottom preheating section in the preheating section, so as to perform rapid flame-muffle preheating and heating on the bottom of the U-shaped silicon carbide pool (4); The lower row of auxiliary burners (10) introduce hot air generated by the cooling section through multiple hot air inlets (6) in the kiln wall in the hot air preheating section of the preheating section, and quickly perform flame-muffle preheating and heating on the bottom of the U-shaped silicon carbide material pool (4); in the bottom preheating section of the preheating section, the multiple lower row of auxiliary burners (10) quickly perform flame-muffle preheating and heating on the bottom of the U-shaped silicon carbide material pool (4) in advance; and in the entire high-temperature section, the multiple lower row of auxiliary burners (10) quickly perform flame-muffle heating and heat preservation on the bottom of the U-shaped silicon carbide material pool (4) in advance.

4. The annular kiln for direct reduced iron according to claim 1, characterized in that: A plurality of upper row main burners (11) and a plurality of lower row auxiliary burners (10) are installed on both sides of the kiln wall (3) of the double-sided heating section in the high-temperature section to heat the reduced material (20) in the U-shaped silicon carbide material pool (4) on both upper and lower sides, so that the reduced material (20) is maintained at 1200-1300°C.

5. The annular kiln for direct reduced iron according to claim 1, characterized in that: The diameter of the rotating chassis (21) is set to 40-80m; the supporting wheel assembly (7) is supported at the lower end of the rotating chassis (21); the supporting wheel assembly (7) is composed of a plurality of tugboats distributed in concentric circles and having a uniform elevation; the rotating chassis (21) performs concentric intermittent circular motion or concentric uniform circular motion.

6. The annular kiln for direct reduced iron according to claim 5, characterized in that: The rotating chassis (21) is configured as a steel structure; the upper and middle parts of the rotating chassis (21) are both inlaid with refractory materials having a thickness of 1200 to 1500 mm.

7. The annular kiln for direct reduced iron according to claim 1, characterized in that: The duration of the reduced material (20) in the preheating section is 1 to 1.5 hours, the reduction time in the high temperature section is 6 to 10 hours, and the duration in the cooling section is 4 to 5 hours.

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