KR100840250B1 - Method for manufacturing molten irons - Google Patents

Abstract

A method for manufacturing molten irons is provided to enhance reduction efficiency and melting efficiency in a melter-gasfier by forming a briquette in a desired strength. 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 non-bituminous coal to the fine iron ore. The non-bituminous coal has a volatile material content of 1 to 11 weight percent and a pulverization degree of 70 or below. Agglomerate is manufactured by forming the mixture. A pig iron is manufactured by charging the agglomerated into the melter-gasifier.

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 coal volatile matter.

3 is a graph showing the compressive strength of the briquette according to the change in coal grinding degree.

* 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 filling layer in the molten gasifier.

Therefore, in order to solve the problem, a method of charging briquettes and molten gasifiers into high temperature briquettes 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, coal briquettes and coal briquettes formed by coal supplied to a 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 molten gasifier, the volatile content in the iron ore is 1 ~ 11wt%, grinding degree Forming a mixture to which non-caking coal is added which is 70 or less, forming a mixture to form a compact, and charging the compact into a melt gasifier to prepare a molten iron.

The volatile matter content of the non-coking coal may be 8 wt% or less. In addition, the degree of crushing of the non-coking coal may be 58 or less. In addition, non-caking coal may be added to 5 ~ 10wt% to the iron ore. In this case, the non-coking coal may be any one of anthracite coal, anthracite coal, and graphite.

The reduced iron hot briquette according to the present invention has a volatile matter content of 1 to 11 wt%, and contains 5 to 10 wt% of non-coking coal having a grinding degree of 70 or less.

Hereinafter, with reference to the drawings will be described an embodiment of the present invention. These 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 illustrated 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 non-coking coal is crushed in the crusher 34, and heated and dried in the powder heating furnace 36. At this time, the non-coking coal has a volatile content of 1 ~ 11wt%, the grinding degree is 70 or less.

When the content of volatile matter is more than 11wt%, the strength of the manufactured briquettes is low, and even the smallest volatile matter non-coking coal has a volatile content of more than 1wt%. Therefore, the volatile matter content of the non-coking coal is preferably 1 to 11 wt%, more preferably 1 to 8 wt%. In addition, since the compressive strength of the produced briquette is similarly low even when the grinding degree is less than 70, the grinding degree is set to 70 or less, more preferably 58 or less.

As described above, the pre-reduced reduced reduction iron and the crushed and heat-dried non-coking coal are supplied to the hot mixer 32 and mixed. At this time, when the addition amount of the non-coking coal to the total mixture is less than 5wt%, when the prepared briquettes are charged and reduced and melted in the molten gasifier 10, the contact area between the reducing iron particles and the non-coking coal particles is increased. Is less. Moreover, when the addition amount exceeds 10 wt%, the compressive strength of the manufactured briquettes falls. Therefore, non-caking coal is added in an amount of 5 to 10 wt% based on the total mixture.

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

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 with a binder stored in the binder feeder 54 to be made into coal briquettes in the cold forming machine 50, and put into the melt 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.

Experimental Example

Partially reduced iron with a particle size of less than 5 mm and a reduction rate of 30 to 60% and non-coking coal with 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 reduced iron and non-coking 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.

The non-coking 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 furnace was fed into a hopper, and it was fed into 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 a briquette by adding a carbon source to partially reduced reduced iron in a fluid reduction furnace, it was intended to derive the conditions of non-coking coal as a carbon source added to maintain the appropriate strength when the prepared briquette is charged into the melt gasifier. The reduced-reduction iron used was partially reduced-reduced iron reduced to 30 to 60% in the fluidized-bed reactor, and semi-annealed coal, anthracite coal, and graphite were used as non-caking coal.

5 wt% and 10 wt% of the carbon source was added to the cyclic iron, and the mixture was heated to 650 ° C. while mixing in a heating furnace, and then manufactured by briquette in a forming roll having a forming pressure of 10 t / cm ² by a hydraulic apparatus. The compressive strength was measured for the briquettes. Figure 2 shows the change in compressive strength of the manufactured briquette according to the volatile content of the non-coking coal as a carbon source.

As shown in FIG. 2, as the volatile content of the added carbon source increases, the compressive strength of the manufactured briquettes decreases initially and then decreases thereafter.

When the amount of carbon source addition is large, the compressive strength of the manufactured briquettes is lowered. 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 a strength of briquettes that can be used in a melt gasifier when manufacturing a carbon source added briquette of about 5 wt%, the volatile content of the added carbon source is preferably 11 wt% or less, and when a carbon source of about 10 wt% is added, It is preferable that the volatile content becomes 8 wt% or less.

Experimental Example 2

5 wt% and 10 wt% of the carbon source was added to the reduced-reduced iron, mixed with a heating furnace, heated to 650 ° C., and then manufactured as a briquette on a forming roll having a forming pressure of 10 t / cm ² by a hydraulic apparatus. The compressive strength was measured for the briquettes. Figure 3 shows the change in compressive strength of the manufactured briquettes according to the degree of grinding of non-coking coal as a carbon source.

As shown in Fig. 3, the compressive strength of the manufactured briquettes decreases as the degree of grinding of the added carbon source is increased, that is, the fracture properties are excellent.

When producing a briquette of about 5 wt% carbon source, the degree of grinding of the added carbon source is preferably 70 or less in order to have the strength of the briquette that can be used in a melt gasification furnace. Is preferably 58 or less.

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 reduced-reduction iron and non-caking coal, and when the carbonaceous-containing briquettes made of reduced-reduction iron are charged into the melt gasifier, It can improve the reduction and melting efficiency within.

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

Claims (7)

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 in which the volatile matter content is 1 to 11 wt% and non-coking coal having a grinding degree of 70 or less in the iron ore, A molding step of preparing a compacted material by molding the mixture, and Preparing molten iron by charging the compacted material into the molten gasifier The molten iron manufacturing method comprising a. According to claim 1, Method for producing molten iron that the volatile content of the non-coking coal is 1 ~ 8wt%. According to claim 1, The molten iron manufacturing method of which the grinding degree of the said non-coking coal is 58 or less. According to claim 1, 5 to 10 wt% of the non-coking coal is added to the iron ore. According to claim 1, The non-coking coal is a method of manufacturing molten iron, which is any one of anthracite coal, anthracite coal and graphite. A reduced iron briquette containing 1-10 wt% of volatile matter and 5-10 wt% of non-caking coal with a crushing degree of 70 or less. The method of claim 6, The non-coking coal is cyclic iron briquette content of 1 to 8wt% or less.

Images