KR100840249B1 - Method for manufacturing molten irons - Google Patents

Abstract

A method for manufacturing molten irons is provided to obtain a briquette having a desired strength by increasing a contact area of fine reduced iron particles and carbon particles. A method for manufacturing molten irons comprises the step of heating and partially deoxidizing fine iron ore in a fluidized reduction reactor(30) using reduction gas generated in a melter-gasifier(10). A mixture is obtained by adding glance coal of 3 to 10 weigt percent to the fine iron ore. Agglomerate is manufactured by forming the mixture at a pressure of 6 to 10 ton per square meter. A pig iron is manufactured by charging the agglomerated into the melter-gasifier. In the step of mixture, the glance coal is heated and dried.

Description

Molten iron manufacturing method {METHOD FOR MANUFACTURING MOLTEN IRONS}

1 is a schematic view showing an embodiment of a molten iron manufacturing apparatus.

2 is a graph showing the compressive strength of the briquette according to the change in the molding pressure.

3 is a graph showing the compressive strength of the briquette with the change in the molding temperature.

Figure 4 is a graph showing the compressive strength of the briquette according to the change in the amount of anthracite coal.

5 is a graph showing the compressive strength of the briquette according to the change in the anthracite coal particle size.

* Explanation of symbols for the main parts of the drawings *

10: melt gasification furnace 12: particle size separator

14: storage hopper 20: reduction furnace

22: supply pipe 24: dust collector

30: flow reduction furnace 32: hot mixer

34: crusher 36: powder furnace

40: hot forming machine 42: storage hopper

50: cold forming machine 52: particle size separator

54: binder feeder

The present invention relates to a molten iron manufacturing apparatus and a manufacturing method, and more particularly, to a molten iron manufacturing apparatus and a molten iron manufacturing method using ordinary coal and powdered iron ore.

The steel industry is a key industry that supplies basic materials to the entire industry, such as automobiles, shipbuilding, home appliances, construction, etc., and is one of the oldest industries with the development of mankind. Steel mills, which play a pivotal role in the steel industry, use molten iron and coal as raw materials to produce molten pig iron, which is then manufactured and supplied to each customer.

Currently, about 60% of the world's iron production comes from the blast furnace method developed since the 14th century. The blast furnace method is a method of producing molten iron by reducing iron ore to iron by putting together coke prepared from sintering process and coking coal as a raw material into a blast furnace.

The blast furnace method, which is a large scale of the molten iron production equipment, requires a raw material having a certain level or more of strength and a particle size capable of ensuring the breathability in the furnace due to its reaction characteristics. As described above, the blast furnace method is a carbon source used as a fuel and a reducing agent. Depends on the coke processed specific raw coal, and the iron source mainly depends on the sintered ore which has undergone a series of agglomeration processes.

As a result, the current blast furnace method necessarily involves preliminary processing facilities such as coke production facilities and sintering facilities. Therefore, it is not only necessary to construct auxiliary facilities other than the blast furnace, but also to the environment for all environmental pollutants generated from the auxiliary facilities. Due to the need for the installation of pollution prevention equipment, there is a problem in that the manufacturing cost is rapidly increased due to the large investment cost.

In order to solve the problems of the blast furnace method, molten reduction of molten iron is produced by directly using general coal as a fuel and a reducing agent in steel mills around the world, and by directly using spectroscopy that occupies 80% or more of the world's ore production as an iron source. Many efforts are being made in the development of the steelmaking method.

The molten iron manufacturing apparatus used for the melt reduction steelmaking method includes a flow reduction furnace in which a bubble fluidized bed is formed, and a melt gasification furnace in which a coal packed bed is formed. At this time, the spectroscopy and subsidiary materials at room temperature are charged into the flow reduction furnace to be preliminarily reduced, and the reducing gas used for flow and reduction of the spectroscopy in the flow reduction furnace is generated and supplied from the melt gasification furnace.

Coal is supplied into the melt gasifier to form a coal filling layer, so that spectroscopic and secondary raw materials at room temperature are melted and slaked in the coal packed layer and discharged into molten iron and slag. Oxygen is blown through a plurality of air vents installed on the outer wall of the melt gasification furnace, and the coal filling layer is combusted to be converted into a high temperature reducing gas and sent to a flow reducing furnace to reduce the spectroscopy and secondary raw materials at room temperature, and then discharge them.

However, in the above-described molten iron manufacturing apparatus, since a high-speed gas stream is formed on the upper part of the molten gasifier, there is a problem in that the branched iron and the calcined auxiliary material charged into the molten gasifier are scattered. In addition, when charging reduced iron and calcined feedstock into the molten gasifier, there is a problem that it is difficult to ensure the air permeability and liquidity of the coal packed layer in the molten gasifier.

Therefore, in order to solve the problem, a method of charging the reduced-reduced iron and calcined subsidiary materials into a high temperature briquette into a melt gasifier has been studied.

As described above, Korean Unexamined Patent Publication No. 96-23095 (Patent No. 117067) is typical as a technique for producing reduced iron by briquettes and charging molten gas furnace to produce molten iron. In the above invention, the iron ore is reduced by the high temperature reducing gas supplied from the molten reduction reactor while passing through the flow reduction step, the reduced reduced iron is stored in the hopper, and then manufactured as a briquette through a hot forming machine, Briquettes are broken up to a certain size and charged into the melt gasifier.

As described above, in the case of producing reduced-reduced iron reduced in briquettes in a flow reduction furnace, the production of briquettes is highly dependent on the physical force of the hot forming machine, that is, the forming pressure. Therefore, the equipment scale of the hot forming machine has to be very large, and there is a problem in that the wear damage of the roll provided in the hot forming machine is severe.

In addition, when the strength of the briquette manufactured as described above is too high and charged into the melt gasifier in the crushing process after the briquette is manufactured, the briquette may be damaged due to reduction and meltability in the melt gasifier, resulting in unstable operation. Cause.

In addition, even in a molten gasifier, briquettes made of reduced iron are in the form of agglomerates and have a low contact area with reducing gas, compared to spectroscopy, resulting in low gas utilization efficiency.

In addition, the coal briquettes and coal briquettes formed by coal supplied to the molten gasifier as a carbon source have a large volume, which is difficult to raise the temperature, and has a fundamental problem of poor briquette reduction and meltability due to the small contact area between the coal mine and the carbon source. Doing.

The present invention is to solve the above problems, the object of the present invention is to increase the contact area of the reduced iron particles and carbon particles to improve the reduction and melting efficiency, so that the briquettes charged into the melt gasifier has an appropriate strength It is to provide a molten iron manufacturing method.

The molten iron manufacturing method according to the present invention is a flow reduction step of heating and partially reducing the iron ore in the flow reduction furnace using a reducing gas generated in the melt gasifier, to form a mixture of 3 ~ 10wt% of anthracite coal in the iron ore Step, forming a mixture at a molding pressure of 6 ~ 10ton / cm ² to produce a compacted material and charging the compacted material in a melt gasifier to produce a molten iron.

The molten iron manufacturing method may further include the step of crushing the anthracite coal so that the upper limit of the particle size is 0.25 ~ 5mm. The molten iron manufacturing method may further include heating and drying the crushed anthracite coal. Molding step may be made by hot briquetting of the molding temperature 450 ~ 650 ℃.

On the other hand, the reduced iron hot briquette according to the present invention contains 3 to 10wt% of anthracite coal having an upper particle size of 0.25 ~ 5mm.

Hereinafter, with reference to the drawings will be described an embodiment of the present invention. Such embodiments of the present invention are merely for illustrating the present invention and the present invention is not limited thereto.

1 is a schematic view showing an embodiment of the apparatus for manufacturing molten iron 100. As shown in FIG. 1, the molten iron manufacturing apparatus 100 may melt molten iron ore and melt gasifier 10 to produce a reducing gas, a reducing furnace 20 to perform a reducing function of iron ore, and a iron ore in advance. It includes a flow reduction furnace 30 for reducing the oil, a hot forming machine 40 for forming the iron ore and a cold forming machine 50 for agglomeration of coal charged to produce a reducing gas in the molten gasifier 10.

The coal introduced into the melt gasifier 10 is gasified to be a reducing gas. The reducing gas is supplied to the lower portion of the third flow reduction furnace 30c through the dust collector 24 and the second flow reduction furnace 30b. And it passes through the first flow reduction furnace (30a) is discharged to the exhaust gas from the upper portion of the first flow reduction furnace (30a).

In the particle size separator 12, fine particles are removed from the iron ore. The fine iron ore from which fine particles have been removed is stored in the storage hopper 14. The iron ore stored in the storage hopper 14 is controlled to a required amount and charged in the first flow reduction furnace 30a, and passes through the second flow reduction furnace 30b and the third flow reduction furnace 30c while melting gasifier ( It is preliminarily reduced by the reducing gas blown from 10).

Although three flow reduction furnaces 30a, 30b, and 30c are shown in FIG. 1, this is only to illustrate the present invention, and two or three or more flow reduction furnaces 30 may be provided.

On the other hand, the anthracite coal is crushed in the crusher 34, and heated and dried in the powder heating furnace 36. At this time, when the upper limit of the particle size of the anthracite coal is less than 0.25 mm, the molding compressive strength of the manufactured briquettes is lowered, and when the upper limit of the particle size is more than 5 mm, the formability of the briquettes deteriorates. Therefore, the particle size of the anthracite coal is crushed to be 0.25 ~ 5mm.

As described above, the pre-reduced reduced reduction iron and the crushed and heat-dried anthracite coal are supplied to the hot mixer 32 and mixed. At this time, when the amount of anthracite added to the total mixture is less than 3wt%, when the manufactured briquettes are charged and reduced and melted in the molten gasifier 10, the contact area between the reducing iron particles and the anthracite particles is small. . Moreover, when the addition amount exceeds 10 wt%, the compressive strength of the manufactured briquettes falls. Therefore, 3-10 wt% of anthracite coal is added with respect to the whole mixture, More preferably, 3-7 wt% is added.

The reduced-reducing iron mixed with anthracite is molded in a hot forming machine 40 equipped with a pair of forming rolls 40a and 40b and stored in a storage hopper 42 as a reduced iron briquette, and then through a reduction furnace 20 to supply a pipe 22. It is charged into the melt gasifier 10 through the ().

At this time, when the molding pressure of the hot forming machine 40 is less than 6ton / cm ^2, the compressive strength of the briquettes is lowered, and when the molding pressure of more than 10ton / cm ² is exceeded, the energy consumption due to the molding is excessively low, the economic efficiency. Therefore, hot forming pressure is 6-10 ton / cm ² , and more preferably 8 to 10 ton / cm ² .

Meanwhile, coal, which is a reducing agent, is sized by the particle size separator 52 and the larger one is directly injected into the melt gasifier 10. In addition, the smaller one is added to the binder stored in the binder feeder 54 to be made into coal briquettes in the cold forming machine 50 and put into the molten gasifier 10.

By the method mentioned above, molten iron is manufactured in the melting gasifier 10. Hereinafter will be described an experimental example for examining the effects of the present invention. The experimental example is for illustrating the present invention, and the present invention is not limited to the following experimental example.

Experimental Example

Partially reduced iron with a particle size of less than 5 mm and a reduction rate of 30 to 60% and anthracite coal having a particle size of 5 mm or less were heated in a heating furnace consisting of an iron cylinder having a diameter of 250 mm and a length of 600 mm.

For uniform heating and mixing of the reduced iron and anthracite coal, a screw-type iron plate was installed on the inner wall of the furnace, and a motor was installed to rotate at an arbitrary speed. In addition, the furnace was allowed to tilt at any inclination to facilitate sample loading and discharge.

A molding machine having a hopper, a screw and a pair of forming rolls was used for briquette production from a mixture of reduced iron and carbon sources. In addition, a hydraulic device and a load cell were installed on a forming roll to produce a briquette at a constant forming pressure.

Anthracite coal dried on the branched iron was added at an arbitrary ratio, and the mixed sample was supplied to the heating furnace, and the heating furnace was inclined at a predetermined angle and heated to a desired temperature using a heater installed on the outer wall.

In addition, by using a hydraulic device to apply a constant molding pressure to the forming roll. The sample heated in the heating furnace was supplied to a hopper, which was supplied to a forming roll subjected to a constant molding pressure by a screw to prepare a briquette. The quality was evaluated by measuring the compressive strength of the manufactured briquettes.

Experimental Example 1

In preparing briquettes by adding a carbon source to partially reduced reduced iron in a fluid reduction furnace, the prepared briquettes are added to form an anthracite and particle size conditions and briquettes added to maintain an appropriate strength for charging into a melt gasifier. We tried to derive the condition.

The reduced iron used was partially reduced reduced iron, about 30-60% in a fluid reduction furnace, and anthracite coal was used as the carbon source. 3 wt% and 7 wt% of anthracite coal (A-coal) was added to the reduced-reduced iron, heated to 650 ° C. while mixing in a heating furnace, and then manufactured as a briquette in a forming roll while varying the forming pressure by a hydraulic device. The compressive strength was measured for.

The compressive strength change of the briquettes manufactured by changing the molding pressure from 6ton / cm ² to 10ton / cm ² by the hydraulic apparatus is shown in FIG. 2.

As shown in Figure 2, the compressive strength of the manufactured briquettes linearly increased as the forming pressure acting on the forming roll. In addition, the compressive strength was found to be the highest when molded into briquettes using 100% reduced iron, and the compressive strength of briquettes decreased as the amount of anthracite coal increased.

This is because the anthracite coal, which has no lowering of the compressive strength when the anthracite coal is added, inhibits the binding of the iron (Fe) component in the branched iron by high forming pressure at high temperature. Usually, the compressive strength required for transporting and charging pellets and compacted ores for use in general blast furnaces is known to be about 50 kgf / cm ² or more (iron and steel, Vol 87, p313 (2001)). In addition, the compression strength of the coal briquettes used in the melt gasifier is about 60 ~ 70kgf / cm ² level.

Therefore, if the strength of the carbon source-containing briquette is also about 70kgf / cm ² or more, it can be used in the melt gasifier. Therefore, in order to have briquette strength that can be used in a melt gasifier, the molding pressure applied to the forming roll should be 6ton / cm ² or more, and the forming pressure acting on the forming roll when adding 7wt% anthracite Should be at least 8 ton / cm ² .

Experimental Example 2

30 to 60% portion of the coal (A tan) in the reduced fine direct reduced iron by mixing the addition of 3wt%, 7wt%, and then heated to the desired temperature with mixing at heating at a predetermined molding pressure of 10ton / cm ² by a hydraulic system so The working rolls were made of briquettes, and the compressive strength of the briquettes was measured.

When the heating temperature of the mixed sample of reduced iron and anthracite (A-coal) in the heating furnace was changed from 450 ° C. to 650 ° C., the compressive strength change of the manufactured briquette is shown in FIG. 3.

As shown in FIG. 3, the compressive strength of the manufactured briquettes linearly increased as the temperature of the sample heated in the furnace, that is, the forming temperature increased. In addition, when the forming pressure in the forming roll is 10 ton / cm ² , it is preferable to heat to 450 ℃ or more in the heating furnace in order to produce a briquette that can be used in the melt gasifier when anthracite coal is added up to 7 wt% to the ring reducing iron.

Experimental Example 3

30 ~ 60% of the partially reduced reduced iron, mixed mixture of anthracite (A charcoal) added to the desired temperature while mixing in a heating furnace and heated to a desired temperature by a hydraulic device to operate a constant molding pressure of 10ton / cm ² A briquette was manufactured on a molding roll, and the compressive strength of the prepared briquette was measured.

4 shows a change in the compressive strength of the manufactured briquette according to the change in the amount of anthracite added to the reduced iron by heating the mixed sample of reduced iron and anthracite (A-coal) in a heating furnace from 450 ° C to 650 ° C.

As shown in Figure 4, as the amount of anthracite (A-coal) is added to the reducing iron, the compressive strength of the manufactured briquettes was found to decrease rapidly. Therefore, when heated to 650 ℃ to form 10 ton / cm ² , anthracite (A-coal) can be added to about 10wt% to the reduced iron, when heated to 450 ℃ to form a low 10 ton / cm ² , It is believed that anthracite (A-coal) can be added to about 7 wt% of the branched iron.

Experimental Example 4

After mixing the mixed sample containing 7wt% of anthracite coal (A-coal) to partially reduced reduced iron, which is 30 ~ 60%, is heated at 450 ℃ and 650 ℃ while mixing in a heating furnace, and then a constant molding pressure of 10ton / cm ² by hydraulic system. The working rolls were made of briquettes, and the compressive strength of the briquettes was measured.

5 shows the change in compressive strength of the manufactured briquette according to the change in particle size (-0.25mm, -1mm, -5mm) of anthracite (A-coal) added to the branched iron.

The particle size of the anthracite coal added was 0.25mm or less, 1mm or less and 5mm or less. As shown in FIG. 5, the compressive strength of the manufactured briquettes was increased as the particle size of the anthracite coal (A-coal) added to the reducing iron increases, that is, the more particles having a larger particle size.

The anthracite particle size added at the preheating temperature of 650 ° C. and the anthracite addition ratio of 7wt% is such that the upper limit particle size is 0.25mm or more. If the preheating temperature is 450 ° C., the anthracite particle size added is controlled to be the upper limit particle size of 1mm or more. desirable.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the range of.

As described above, the method for producing molten iron according to the present invention enables the production of briquettes of appropriate strength from the reduced iron and anthracite coal, and when the carbon material containing briquettes made of the reduced iron are charged into the molten gasifier, The reduction and melting efficiency can be improved.

In addition, as the carbonaceous material-containing briquettes are used for melt gasification, productivity is increased and energy efficiency is improved.

Claims (8)

A flow reduction step of heating and partially reducing the iron ore in the flow reduction furnace by using the reducing gas generated in the melt gasifier; Forming a mixture of 3 ~ 10wt% anthracite coal to the iron ore, A molding step of forming a compacted body by molding the mixture at a molding pressure of 6 to 10 ton / cm ² , and Preparing molten iron by charging the compacted material into the molten gasifier The molten iron manufacturing method comprising a. According to claim 1, In the step of forming the mixture, molten iron manufacturing method for adding 3 ~ 7wt% of the anthracite coal. According to claim 1, In the forming step, the molten iron manufacturing method to the molding pressure of 8 ~ 10ton / cm ² . According to claim 1, In the step of forming the mixture, the anthracite coal is crushed molten iron so that the upper limit of the particle size is 0.25 ~ 5mm. The method of claim 4, wherein In the step of forming the mixture, the anthracite coal is heated to dry molten iron manufacturing method. According to claim 1, The forming step is a molten iron manufacturing method consisting of hot briquetting of the molding temperature 450 ~ 650 ℃. An iron-reducing briquette containing 3-10 wt% of anthracite coal having an upper particle size of 0.25-5 mm. The method of claim 7, wherein Reduction iron briquettes containing 3 to 7 wt% of the anthracite coal.

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