KR100391914B1 - Process for coal based ironmaking to reduce loss of fine ore - Google Patents

Abstract

The present invention relates to an operation termination method of a molten iron manufacturing process using plain coal and iron ore, the purpose of which is to reduce the residual iron ore of the reduction furnace at the end of the operation of the molten iron manufacturing process using plain coal and iron ore directly Therefore, the present invention provides a method of reducing the amount of iron ore lost by supplying the molten gasifier to the maximum, thereby improving the use efficiency of the raw ore.

The present invention for achieving the above object, one or more preliminary reduction path (3, 4 ...) and the final reduction path (2), which is configured to reduce the charged iron ore;

A molten gasifier (1) configured to receive molten reduced iron from the final reduction furnace (2) to melt-reduce and manufacture molten iron;

The melt gasifier 1 supplies the exhaust gas to the reducing gas of the reducing furnaces 2, 3, and 4 through the reducing gas supply pipe 6, and the reducing furnaces 2, 3, and 4 are ore charging pipes 5c. In the molten iron reduction method using a molten reduction apparatus configured to be connected to the molten gas furnace 10 in the ore communication relationship through, 5b, 5a),

The reduction furnace (2, 3, 4) is configured to be connected to the molten gasifier 10 in the residual iron ore communication through the residual iron ore discharge pipe (7c, 7b, 7a),

Stopping charging of the iron ore into the first preliminary reduction furnace (4) at the end of the operation;

Closing the ore charge pipe 5c of the first preliminary reduction reactor 4 and opening the residual iron ore discharge pipe 7c to discharge the residual iron ore to the second preliminary reduction reactor 3 for reduction;

Discharging the residual iron ore in the preliminary reduction furnace in sequence as described above, and finally reducing the residual iron ore in the final reduction furnace (2) and supplying the molten gasifier (1);

When the supply of the residual iron ore of the final reduction furnace (2) is completed, the method for manufacturing molten iron using a general coal with a low loss of residual iron ore, including the step of ending the operation by stopping the supply of reducing gas to the reduction furnace I make that technical point.

Description

Process for coal based ironmaking to reduce loss of fine ore}

The present invention relates to an operation termination method of the molten iron manufacturing process using ordinary coal and powdered iron ore, more specifically, to change the discharge path of the residual iron ore in the reactor at the end of the operation to suppress the loss of the iron ore as much as possible to improve productivity It relates to a method for manufacturing molten iron that can be made.

In general, the blast furnace method, which constitutes a large scale of molten iron production equipment, requires a raw material having a strength of more than a certain level and particle size to ensure the ventilation in the furnace due to the characteristics of the reactor. Therefore, as a carbon source used as a fuel and a reducing agent, it depends on coke which processed the specific raw coal, and as an iron source mainly depends on the sintered ore which passed through the series of agglomeration processes. Accordingly, the current blast furnace method must involve raw material pretreatment facilities such as coke production facilities and sintering facilities. The competitiveness of the current blast furnace method is rapidly being eroded by the costs required for the construction of such ancillary facilities and enormous facility investment costs for preventing environmental pollution caused by various environmental pollutants generated in the ancillary facilities.

Therefore, countries around the world are directly using general coal as fuel and reducing agent, and as a source of iron, they are spurring the development of new steel making process to manufacture molten iron by directly using spectroscope which occupies 80% or more of the world's ore production. For example, the Austrian patent application No. AT2096 / 92 is proposed as a molten iron manufacturing apparatus using conventional coal and spectroscopy directly related to this technology.

A representative example of molten iron manufacturing equipment using plain coal and spectroscopy is shown in FIG. 1. This molten iron manufacturing facility comprises a three-stage reduction bed (2, 3, 4) for reducing the iron ore while forming a fluidized bed, and a molten gasifier (1) in which a coal packed bed is formed. The high temperature spectroscopy of the room temperature charged in the first preliminary reduction reactor 4 at the uppermost stage is brought into contact with the high temperature reduction air stream supplied from the molten gasifier while passing through the three stages of the fluid reduction reactor. It is converted into reduced spectroscopy of and discharged.

The reduced spectroscopy is continuously charged in the molten gasifier 1 in which the coal packed layer is formed, melted in the coal packed layer, and converted to molten iron and discharged to the molten gasifier. The molten gasifier is continuously supplied with coarse coal from the upper part of the furnace to form a coal packed layer having a constant height in the furnace. In the packed layer, oxygen is supplied through a plurality of air holes formed at the bottom of the outer wall of the packed layer. The combustion gas generated by the combustion of coal in the packed bed is converted into a high temperature reducing gas while rising the packed bed and discharged out of the molten gasifier to be supplied to the three-stage flow reduction reactor.

The movement of each flow reaction period of the ore passing through the three-stage flow reduction path is performed through the ore charge pipes 5a, 5b, and 5c connecting the adjacent flow reduction paths of the upper and lower ends with each other. In the charging pipe, due to the pressure difference between the upper and lower ends, the high-temperature reduction gas flow formed from the lower flow reduction to the upper flow reduction path and the ore flow formed from the upper flow reduction to the lower flow reduction path by gravity cross each other. Will be formed. On the other hand, the differential reduction ore discharged continuously from the final reduction path is discharged through the ore charge pipe (5a), the discharged differential reduction ore according to the height difference formed between the final reduction path discharge position and the melting furnace upper position When the final reduction furnace discharge position is low, it is charged into the melting furnace by air flow by a portion of the high temperature reducing gas supplied to the three stages of the flow reduction reactor. On the other hand, when the discharge position of the final reduction furnace is high, it is charged into the melting furnace by its own gravity of the differential reduction ore.

Although it is considered that the molten iron manufacturing process using the ordinary coal and the iron ore is advantageous in comparison with the existing process, the iron ore is used instead of the lump or the coal is used instead of the coke, but due to the nature of the process, the equipment is stopped and restarted. This is easy. However, due to the nature of the process of using the iron ore as a raw material, careful attention is required for the rest of the equipment. That is, the fluidization of the fluidized bed must be maintained at the end of the operation in the operating situation in which the fluidized bed is formed by the reducing gas supplied from the bottom of each reactor.

If the ferrous iron ore that has been fluidized is shut down to the bottom of the reactor by shutting off the supply of reducing gas at the end of the operation, there is a situation of blocking the nozzle of the gas distribution plate installed for the purpose of uniform gas flow in the bottom of the reactor. Without maintenance, restarting is difficult. In addition, since the iron ore outlet of each reactor is located in the upper part of the fluidized bed, the emission of iron ore from the iron ore outlet is limited, and even though the iron ore is discharged from the iron ore outlet until no more iron ore is discharged, A significant amount of iron ore still remains from the upper part of the gas distribution plate to the iron ore outlet, and the problem of clogging of the gas distribution plate appears as it is if the remaining iron ore also stops fluidization in the state.

Therefore, in the present state, while maintaining the flow of reducing gas, in each reactor, while maintaining the fluidized state of the iron ore in the reactor through the residual iron ore discharge pipe directly above the gas distribution plate, rather than the conventional iron ore outlet, It takes the form of draining iron ore until iron ore is not discharged. At this time, the ore charge tube, which is operated in an open state at all times, is closed by a valve, and a fluidized bed is formed in each reactor, and the ores in operation are not discharged to the other reactors, but are discharged to the outside. At this time, the discharged iron ore is not yet completed the reduction reaction, so it is not disposed of in the molten gasifier, which is a lower process, is disposed of. At this time, the amount of iron ore disposed of is about 5 tons per reactor for an experimental facility of 30,000 tons per year, and 100 tons per reactor for an annual 600,000 tons plant under consideration.

In the molten iron manufacturing process using direct coal and iron ore directly, unlike other molten iron manufacturing processes, the operation and reactivation are expected to occur frequently, and thus, the termination and reactivation of unreduced iron ore that is discharged and disposed of at the end of the operation is expected. It is expected to increase in proportion to the number of times.

The present invention is supplied to the molten gasifier by sequentially reducing the unreduced residual iron ore in the reduction furnace in the pre-reduction furnace and the final reduction furnace at the end of the operation of the molten iron manufacturing process using the direct coal and fine iron ore. It is an object of the present invention to provide a method of minimizing the amount of iron ore lost by maximizing the efficiency of use of raw ore and productivity of the process.

1 is a schematic diagram of a molten iron manufacturing process using ordinary coal.

2 is an example of a molten iron manufacturing process to which the present invention is applied.

Explanation of symbols on the main parts of the drawings

1 ..... Melt Gasification Furnace 2 ..... Final Reduction Furnace

3, 4 ..... Preliminary Reduction Furnace 5 .....

6 ..... Reducing gas supply pipe 7 ..... Residual iron ore discharge pipe

8 ..... gas discharge pipe

In the molten iron manufacturing method of the present invention for achieving the above object, one or more preliminary reduction furnace and final reduction furnace configured to reduce the charged iron ore, the reduced reduction iron is supplied from the final reduction furnace to produce molten iron A melt gasifier is configured to supply, wherein the melt gasifier is supplied to the reducing gas of the reducing furnace through the reducing gas supply pipe, the reducing furnace is connected to the molten gasifier in the ore communication relationship through the ore charge pipe In the molten iron manufacturing method using a melt reduction device is configured,

The reduction furnace is configured to be connected to the molten gasifier through the residual iron ore communication through the residual iron ore discharge pipe,

At the end of the operation, stopping the loading of the iron ore into the first preliminary reduction reactor of the preliminary reduction reactor,

Closing the ore charge pipe of the first preliminary reduction reactor and opening the residual iron ore discharge pipe to discharge residual iron ore to the second preliminary reduction reactor to reduce the ore;

Discharging the residual iron ore in the preliminary reduction furnace in sequence as described above, and finally reducing the residual iron ore in the final reduction furnace and supplying the molten gasifier;

Comprising the step of terminating the operation by stopping the supply of reducing gas to the reducing furnace when the supply of the residual iron ore to the final reduction furnace is completed.

Hereinafter, the present invention will be described in detail with reference to FIG. 2.

In the present invention, as shown in Figure 1 in the molten iron manufacturing facilities using coal and fine iron ore charged into the molten gasifier (1) through the preliminary reduction reactor and the final reduction furnace without discarding the residual iron ore of the preliminary reduction reactor and the final reduction reactor. It can be reused effectively, and there is a characteristic.

The present invention can be applied to two or more stages of fluidized-bed reduction reactor, where the case of applying to the three-stage fluidized-bed reduction reactor as shown in FIG.

FIG. 2 differs in that in FIG. 1, the residual iron ore discharge pipes 7c, 7b, and 7a of the reduction furnaces 2, 3, and 4 are connected to the following reactors so as to be connected in an ore communication relationship. Residual iron ore discharge pipe 7c of the first preliminary reduction reactor 4 is connected near the upper portion of the dispersion plate (not shown) of the second preliminary reduction reactor to discharge the residual iron ore. The same applies to the second reduction reactor. It is more preferable that these residual iron ore discharge pipes 7c and 7b are located at a height similar to that of the supply port of the ore charge pipe. The reason is that the ore density is low at the supply portion of the ore charge pipes 5b and 5a rather than directly on the dispersion plate having a relatively high density of iron ore, so that smooth ore supply is possible. Of course, it is also possible to connect the residual oil-iron ore discharge pipe (7c, 7b) to the ore charge pipe (5b, 5a). It is most preferable that the residual iron ore discharge pipe 7a of the final reduction path 2 is connected to the ore charge pipe 5a.

An embodiment of a molten iron manufacturing method using the melt reduction apparatus according to the present invention will be described in detail with reference to FIG.

At the end of the operation, first, the loading of the iron ore into the first preliminary reduction reactor (4) is stopped. Subsequently, the first ore charge pipe 5c of the first preliminary reduction reactor 4 is closed and the first residual iron ore discharge pipe 7c is opened to discharge residual iron ore to the second preliminary reduction reactor 3. . At this time, when the discharge of the residual iron ore of the first preliminary reduction reactor 4 is completed, the first residual iron ore discharge pipe 7c is closed.

When the reduction of the residual iron ore in the second preliminary reduction path 3 is completed, the second ore charged pipe 5b is closed and the second residual iron ore discharge pipe 7b is opened to reduce the residual iron ore reduced to the final reduction path. It is discharged to (2) and reduced. Similarly, when the discharge of the residual iron ore of the second preliminary reduction reactor 3 is completed, the second residual iron ore discharge pipe 7b is closed.

As described above, when the supply of the residual iron ore of the final reduction path 2 is completed, the third residual iron ore discharge pipe 7a is closed and the supply of reducing gas to the reduction furnace is stopped to terminate the operation.

As described above, in the present invention, residual iron ore is discharged in the order of the first preliminary reduction reactor 4, the second preliminary reduction reactor 3, and the final reduction reactor 2. Through this discharge process, the residual iron ore discharged from the final reduction reactor (2) shows a reduction degree similar to the reduced iron supplied to the molten gasifier (1) from the final reduction reactor (2) during normal operation. In the normal operating situation, the reduction rate of discharged ore is about 85%, so even if the reduction rate of residual iron ore has a reduction rate of about 80%, it can be used sufficiently in the melt gasifier, and also as a raw material for making intermediate workpieces such as HBI. Not lacking

The present invention is not limited to the embodiment of FIG. 2 described above. The said embodiment is an illustration, Comprising: It is comprised in the technical scope of this invention in any thing to have a structure substantially the same as the technical idea described in the claim of this invention, and to provide similar effect. For example, in the above-described embodiment, an example has been described for reducing the residual iron ore in a three-stage fluidized-bed reduction furnace, but the present invention is not limited thereto, but in a two-stage fluidized-bed reduction furnace or more fluidized-bed reduction furnace. Applicable when operating.

As described above, the present invention can minimize the amount of iron ore lost by the final reduction of the unreduced iron ore into the molten gasifier at the end of the operation of the molten iron manufacturing process using plain coal and iron ore ore directly In addition, the efficiency of use of the raw ore and the productivity of the process can be increased.

Claims (2)

One or more preliminary reduction furnaces (3, 4 ...) and the final reduction furnace (2), which is configured to reduce the charged iron ore is supplied to the molten reduction iron from the final reduction furnace (2) to produce molten iron Including melt gasifier 1, The melt gasifier 1 supplies exhaust gas to the reducing gas of the reducing furnaces 2, 3, and 4 through the reducing gas supply pipe 6, and the reducing furnaces 2, 3, and 4 are filled with ore charge pipes ( In the molten iron reduction method using a molten reduction apparatus configured to be connected to the molten gasifier 10 in the ore communication relationship through 5c, 5b, 5a), The reduction furnaces (2, 3, 4 ...) is configured to be connected to the molten gasifier 10 in the residual iron ore communication through the residual iron ore discharge pipe (7c, 7b, 7a), Stopping charging of the iron ore into the first preliminary reduction furnace (4) at the end of the operation; Closing the ore charge pipe 5c of the first preliminary reduction reactor 4 and opening the residual iron ore discharge pipe 7c to discharge the residual iron ore to the second preliminary reduction reactor 3 for reduction; Discharging the residual iron ore in the preliminary reduction furnace in sequence as described above, and finally reducing the residual iron ore in the final reduction furnace (2) and supplying the molten gasifier (1); When the supply of the residual iron ore of the final reduction path (2) is completed, stopping the supply of the reducing gas to the reduction furnace comprising the step of ending the operation, molten iron manufacturing method using a general coal with a low loss of residual iron ore. The method of claim 1, wherein the residual iron ore discharge pipe (7a) of the final reduction path (2) is connected to the ore charge pipe (5a).