KR940008446B1 - Making method & device of iron - Google Patents

Abstract

The method is characterized by using a prereducing furnace having a many fluidized bed for manufacturing pig iron from a powder iron of wide range particle distribution. The prereducing furnace consists of one turbulent fluidized bed (4) and three bubbling fluidized beds (1,2,3) for enhancing utilization of gas.

Description

Method and apparatus for producing pig iron from iron ore

1 is a schematic diagram of a fluidized bed preliminary reactor.

2 is a schematic diagram of a melt reduction reactor.

3 is a schematic diagram of a combination of a fluidized bed preliminary reactor and a melt reduction reactor.

4 is gas utilization rate in the preliminary reduction reactor to match the productivity of the melt reduction reactor and the preliminary reduction reactor.

5 is the relationship between the gas utilization rate and the reduction rate in the preliminary reduction reactor.

* Explanation of symbols for main parts of the drawings

1: Yebin reduction path 1. (bubble / turbulent fluidized bed) 2: preliminary reduction path 2. (bubble / turbulent fluidized bed)

3: preliminary reduction reactor 3. (bubble / turbulent fluidized bed) 4: preliminary reduction reactor 4. (circulating fluidized bed)

5: ore barrel 6: high temperature cyclone

7: off-gas outlet 8: coal barrel

9: melt reduction furnace 10: high temperature cyclone

The present invention relates to a method and apparatus for producing pig iron from iron ore having a wide particle size range by using a melt reduction reactor of a multistage fluidized bed preliminary reactor.

The multistage fluidized bed preliminary reactor is composed of one turbulent fluidized bed and three bubbled fluidized beds to increase gas utilization, and the melted reactor is the final reduction, melting and high temperature of the preliminary reduced ore. It also serves to produce highly reducing gases.

By using the high temperature and high reducing gas generated in the molten reduction reactor by inputting the ferrite ore with wide particle size range into the bubble fluidized bed, more than 0.5mm is reduced in the three bubble fluidized beds and the following is reduced in the circulating fluidized bed. To prepare pig iron.

Conventional pig iron is mainly manufactured by the blast furnace method, which has increased the productivity and output by increasing the size, continuity, and speed of the blast furnace, but it lacks the flexibility of the operation and requires high quality coke and lump, which requires huge investment cost for the auxiliary equipment. And environmental pollution problem appeared.

In order to overcome this problem, it is required to develop a process that can be used as it is without processing coal seat spectroscopy and has excellent operation flexibility. The steelmaking method that can replace the blast furnace is a solid reduction iron-electric furnace method and a melt reduction method. The former is called direct reduction, and iron ore is reduced in the solid state to produce reduced iron and dissolved in an electric furnace. With the advance of reducing gas manufacturing technology, a process has been developed that can deal with lumps and spectroscopy mainly in natural gas producing countries. The process of reducing spongy iron to produce sponge iron has a shaft-type Midrex process, and the process of reducing spectroscopy to produce sponge iron is a fluidized bed-type fior. There is a law.

The melt reduction method includes a method of directly melting iron ore and reducing it, and a method of preliminarily reducing the amount of preliminary reduction in a solid state, followed by melt reduction. The latter has been widely used in terms of energy efficiency and operation. In this two-stage melt reduction process, the high-temperature, high-reduction gas generated from the lower melt reduction reactor is supplied to the upper preliminary reduction reactor to pre-reduce iron ore, thereby effectively utilizing the sensible heat and reducing power of the exhaust gas of the melting reduction reactor. have. In addition, the iron ore is pre-reduced and supplied to the molten reactor, thereby reducing the heat load of the molten reactor, reducing the carbon ash consumption and exhaust gas generation, and reducing the amount of ferrous oxide (FeO) in the slag, thereby reducing the erosion of the refractory. . In this case, the overall productivity may vary depending on how the preliminary reduction rate is adjusted in the preliminary reduction process. In the Midrex or FIOR method of reforming natural gas to produce high temperature and high reducing gas, iron ore is maintained at high reduction rate (90% or more) by using this high temperature and high reducing gas. Manufacture. Unlike the blast furnace method, the sponge iron obtained in these processes is quite clean iron (C <1%, S <0.02, P <0.1), so it can be used as a scrap in the LD converter process or directly melted and decarburized in an electric furnace. It can manufacture.

In areas where natural gas is not produced, there is a method of manufacturing high-temperature, high-reducing gas with coal, and then manufacturing spongy iron in a preliminary reduction furnace to produce steel by melting and decarburizing in an electric furnace. As in the) process, there is a method of producing pig iron by treating a gas manufacturing process and a melting process of high-preliminary reduced iron (90% or more) in a single container.

In the case of producing pig iron by burning coal to produce high temperature, high reducing gas and dissolving the high-preliminary reducing iron (90% or more) produced by using this gas in a single container, the conventional process is to produce iron ore. Direct use is not possible. For direct use of spectroscopy, the fluidized bed must be used to form a bubble fluidized bed or a circulating fluidized bed for reduction. In the case of reduction by forming a bubble fluidized bed or a circulating fluidized bed, gas utilization becomes very low, and in order to manufacture pig iron using spectroscopy directly, process development to increase gas utilization in a fluidized bed must be accompanied.

In Korean Laid-Open Patent Publication No. 86-388, there is a restriction that the size of sponge iron or preliminary reducing ore is 3 mm or more, and in Patent Publication No. 88-5276, iron ore of 10 to 30 mm is reserved by using a shaft-type preliminary reducing reactor. Reduce. In this case, gas utilization is improved, but there is a restriction that the use of spectroscopy is not possible.

Therefore, in order to increase the direct use of spectroscopy and gas utilization, four preliminary reduction reactors are installed, and the medium / elastic iron ore is the bubble / turbulent fluidized bed in the first, second and third preliminary reduction reactors, and the fine iron ore is the fourth reserve reduction reactor. The formation of a circulating fluidized bed prevents overload in the pre-reduction reactor and stabilizes the flow, thus making it possible to uniformize the reduction rate of iron ore with a wide particle size distribution and improve gas utilization.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows the first, second, and third preliminary reduction paths (1, 2, 3) of heavy / opposed (0.5 mm or more and 5 mm or less) light among the iron ore supplied from the ore barrel 5 to the first preliminary reduction path 1. 3) while reducing the bubble or turbulent fluidized bed, the fine (0.5mm or less) iron ore is partially reduced in the case of pre-reduction (1, 2, 3) and finally made in the fourth preliminary reduction reactor Obtain a high reduction rate.

2 is a schematic view of a typical melt reduction reactor. It plays a role of reducing and melting some of the pre-reduced iron ores supplied from the preliminary reduction reactor and producing reducing gas to be supplied to the preliminary reduction reactor. Coal is introduced into the coal barrel (8), the medium / alley is composed of a system to be injected into the upper portion of the molten reduction path (9) along a predetermined path, the unspectralized light is injected into the lower portion of the molten reduction path (9) along a predetermined path. .

3 is a combination of FIG. 1 and FIG. The main configuration of FIG. 3 is that the exhaust gas generated in the lower part of the melt reduction reactor 9 can maximize the gas utilization rate in the preliminary reduction reactor and can directly use the spectroscopic particle having a large particle size distribution while maintaining the balance of productivity of the lower part and the upper part.

In addition, in order to input the undifferentiated reduced in the fourth preliminary reduction reactor (4) to the molten reduction reactor (9) there is a problem of reoxidation of the reduced iron ore and hot briquetting. This method is characterized by directly feeding the reduced fine spectroscopy into the molten reduction reactor by using the exhaust gas discharged from the fourth preliminary reduction reactor.

The present invention will be described in more detail as follows. As shown in FIGS. 1 to 3, the iron ore supplied from the ore barrel 5 to the first preliminary reduction reactor 1 is discharged from the molten reduction reactor 9 and is discharged by the high temperature cycle 10. Gravity to the upper part of the molten reduction reactor (9) by primary pre-reduction of 0.5mm or more of the medium and alleles while forming a bubble / turbulent fluidized bed by reducing gas collected and partially supplied to the lower part of the first preliminary reduction reactor (1) Dropping and dropping, the heavy and opposing light entrained in the first preliminary reduction path (1) is introduced into the second preliminary reduction path (2) installed in series with the first preliminary reduction path (1), wherein By the same method, the secondary preliminary reduction is performed while forming a bubble / turbulent fluidized bed by a reducing gas partially supplied to the lower part of the second preliminary reduction reactor 2, and a gravity drop is introduced into the upper portion of the melt reduction reactor 9, and the second The intermediate and opposing minerals entrained in the preliminary reduction path (2) are connected to the third reserve reduction path (3) installed in series with the second reserve reduction path (2). The third preliminary reduction is carried out by forming a bubble / turbulent fluidized bed by a reducing gas which is partially supplied to the lower part of the third preliminary reduction reactor 3 by the same method as described above, and gravity to the upper part of the melt reduction reactor 9 is obtained. In the drop-in step, the pre-reduction step of medium and allied light having a particle size of 0.5 mm or more is completed.

On the other hand, particulates having a particle size of 0.5 mm or less are entrained in the third preliminary reduction reactor (3) and introduced into the fourth preliminary reduction reactor (4), which is a circulating fluidized bed type installed in series with the third preliminary reduction reactor (3). And the fourth preliminary reduction reactor 4 while forming a circulating fluidized bed by reducing gas which is collected by the high temperature cyclone 10 and partially supplied to the lower part of the fourth preliminary reduction reactor 4. It is pre-reduced while being circulated by the high temperature cyclone (6) installed in communication with one side of the is introduced into the lower portion of the melt reduction reactor (9). At this time, a portion of the exhaust gas discharged to the exhaust gas outlet 7 formed in the upper portion of the high temperature cyclone 6 is directly introduced into the lower end of the molten reduction reactor 9 through the CC 'shaft, and the exhaust gas is the fourth It is to be used as a transport gas of the reduced unspectralized to naturally feed the reduced unspectralized in the preliminary reduction reactor (4) to the melt reduction reactor (9).

Embodiments of the present invention are as follows. In case of preliminary reduction of spectroscopy in the preliminary reduction reactor using high temperature and high reduction gas generated from the melting reduction reactor, the gas utilization rate can be calculated from the material and energy balance calculation to make the productivity of the preliminary reduction furnace and the molten reduction reactor equal. have.

4 shows the gas utilization rate in the preliminary reduction reactor to match the productivity of the preliminary and the molten reduction reactor.

This calculation is calculated under the following conditions. When (% T, Fe) in iron ore is 60%, the coal required per ton of iron is about 1 ton in order to maintain the pre-reduction rate at 90% in the preliminary reduction furnace. The minimum gas utilization rate was calculated in the preliminary reactor to maintain the productivity of the preliminary reactor and the melt reactor. From the figure, it can be seen that the minimum gas utilization rate in the preliminary reduction reactor is 23.2% to match the productivity of the preliminary reduction reactor and the melt reduction reactor. When the utilization rate of the preliminary reactor is lower than that of the gas, the productivity of the preliminary reactor is lower than that of the molten reactor, resulting in production difficulties. Conversely, if it is higher than this gas utilization rate, there is a possibility that extra gas can be used in addition to the preliminary reduction. Therefore, it is necessary to construct a process that can increase the gas utilization rate in the preliminary reduction reactor if possible.

5 shows the results obtained by experiments on the average gas utilization in the first preliminary reduction reactor of FIG. Experimental conditions were to measure the reduction rate and average gas utilization rate according to the temperature at 1-5mm spectroscopy, gas flow rate 4m / sec. From the figure, it can be seen that the average gas utilization rate is about 5.6% although the preliminary reduction rate is more than 80% depending on the temperature. Similar results were obtained for the average gas utilization in the fourth preliminary reduction reactor, which is a circulating fluidized bed. Therefore, in order to satisfy the gas utilization rate of 23% to match the productivity of the preliminary reduction reactor and the melting reduction reactor shown in FIG. 4, four preliminary reduction reactors should be connected in series to match the gas utilization rate as shown in FIG.

Claims (2)

In the method for producing pig iron from the iron ore having a wide particle size range by using a fluidized bed preliminary reduction furnace and a melt reduction reactor, medium and large grains having a particle size of 0.5 mm or more among the iron ore introduced into the first preliminary reduction reactor (1). Light is discharged from the molten reduction reactor (9), collected in the high temperature cyclone (10), and reduced gas partially supplied to the lower part of the first, second and third preliminary reduction reactors (1, 2, 3) that are delivered in series By the first, second, third preliminary reduction reactors (1, 2, 3) to form a bubble / stove fluidized bed, the first, second, third preliminary reduction is introduced into the top of the melt reduction reactor (9), 0.5 mm or less which is finally entrained in the third preliminary reduction path 3 via the first, second and third preliminary reduction paths 1, 2, and 3 and introduced into the lower part of the fourth preliminary reduction path 4. The fine spectroscopy having the particle size is discharged from the melt reduction reactor (9) to form a circulating fluidized bed by the reducing gas introduced into the lower portion of the fourth preliminary reduction reactor (4) While pre-reduced while being circulated to the high temperature cyclone (6) is introduced into the lower portion of the melt reduction reactor (7) while some exhaust gas discharged from the high temperature cyclone (6) is circulated to the bottom of the melt reduction reactor (9) through the CC 'path A method for producing pig iron from iron ore in which reduced fine spectroscopy is directly introduced into a lower portion of a melting reduction furnace (9). In the apparatus for producing pig iron from a wide range of particle size ore using a fluidized bed pre-reduction reactor and a melt reduction reactor, the first preliminary reduction reactor for reducing the medium / allele iron ore while forming a bubble / turbulent fluidized bed (1) The second preliminary reduction reactor (2), the third preliminary reduction reactor (3) and the fourth preliminary reduction reactor (4) for reducing the fine iron ore while forming a circulating fluidized bed in series communication with the first, second, third The preliminary reduction reactors (1, 2, 3) are connected to the upper part of the melt reduction reactor (9), and the lower part of the fourth preliminary reduction reactor (4) communicates with the lower part of the melt reduction reactor (9) and the fourth preliminary reduction reactor On the upper side of the furnace, a hot cyclone 6 having an exhaust gas outlet 7 formed thereon is in communication with the pig iron ore from the iron ore obtained by communicating the exhaust gas outlet 7 with the lower portion of the melt reduction reactor 9. Device for manufacturing.