JPH0196313A - Smelting reduction method - Google Patents

Abstract

PURPOSE:To restrain erosion or wear of tuyeres at furnace wall or furnace bottom and to promote reduction velocity of iron ore by blowing O2 from top blowing lance and inert gas as stirring gas or process gas from the tuyere, respectively and charging the whole raw material from upper part of a smelting furnace. CONSTITUTION:Iron ore is charged into a preheat and pre-reduction furnace 30 from a second chute 31 and after preheating and pre-reducing with generating gas supplied from the smelting furnace 10 through the introducing pipe 33 in here, it is charged into the furnace 10 through a chute 32. Further, carbonic material and slag making as sub-raw material are charged into the furnace 10 through a first chute 13. The charged main raw material and the sub-raw material are stirred by the inert gas blown from the tuyeres 25, 26 arranged at side wall and bottom part of the furnace 10 or the gas generating in the furnace 10 to quickly and uniformly mix into molten iron or slag layer formed in the furnace. On the other hand, O2 is supplied from the nozzles 22, 23 for decarbonization and secondary combustion in the oxygen lance 21 to oxidize the carbonic material, and sufficient heat source for reducing the iron ore is supplied.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a smelting reduction method in which iron ore is reduced in a molten state in a converter-type smelting furnace using carbonaceous materials as fuel and reducing material.

[Conventional technology] The smelting reduction method is an alternative to the blast furnace iron making method, and it eliminates the drawbacks of the blast furnace iron making method, such as the high construction cost and the need for a large site. It has been developed in recent years.

In this reduction method, iron ore or pre-reduced iron ore is charged into hot metal in a smelting furnace, and carbonaceous materials, lime and other slag materials are charged as reducing agents or fuel. Oxygen is blown into the furnace.

Then, the carbonaceous material is dissolved in the hot metal, and the carbonaceous material is dissolved in the hot metal.
is oxidized by oxygen gas. The iron ore is melted by the oxidation heat at this time, and the iron ore is
will be reduced by The CO gas generated from the hot metal is subjected to secondary combustion by the excessively blown oxygen gas and becomes CO2 gas. The sensible heat of this CO2 gas is transferred to the slag and foamed iron particles covering the hot metal, and then to the hot metal.

In this way, the iron ore is reduced to produce hot metal, but in order to promote the reduction reaction of the iron ore in the smelting furnace, the iron ore or carbon material is provided on the side wall or bottom of the smelting furnace. A method of charging together with carrier gas through the tuyere has been proposed. (JP-A-58-14407, JP-A-60-145
307) [Problems to be Solved by the Invention] However, in the method of injecting iron ore or carbonaceous material from the tuyere on the side wall or bottom of the smelting furnace using a carrier gas, the tuyeres are subject to severe erosion and wear. In addition, in order to increase the amount of iron ore or carbonaceous material injected, it is necessary to increase the carrier gas, but this causes a phenomenon of blow-through, resulting in poor yields in which the iron ore or carbonaceous material remains in the slag or hot metal. Become.

Further, when the raw material is blown into the nozzle of the oxygen lance or the tuyere, it takes time for the blown raw material to be uniformly mixed in the smelting furnace, and the reaction may be slow. Furthermore, when carbonaceous material is injected through an oxygen lance, the reaction inside the furnace becomes uneven, and the iron content (T-Fe) in the slag decreases.
There is a problem in that a high area is formed and the slag in the furnace is scattered, resulting in so-called slopping.

This invention was made to solve these problems, and aims to promote the degree of reduction of iron ore by suppressing the melting or wear of the tuyere on the furnace wall or the bottom of the furnace, and the generation of slothbinku. The purpose of the present invention is to provide a melt reduction method that reduces the

[Means and effects for solving the problems] The smelting reduction method according to the present invention adds carbonaceous material and oxygen to an iron bath in a smelting furnace, and preheats and prereduced iron ore in a preheating and prereducing furnace. In the method of producing hot metal by charging it into a smelting furnace and reducing it by smelting, oxygen is blown through a top-blown oxygen lance that has decarburization and secondary combustion nozzles, and inert gas or gas generated in the smelting furnace is blown into it. The smelting furnace is characterized in that the iron ore, carbonaceous materials, and slag materials are all blown into the furnace from the tuyeres provided on the side walls and the bottom wall of the furnace, and are dropped from above the smelting furnace.

Iron ore, carbonaceous materials, lime, etc. are all dropped into the furnace from a charging hopper installed above the furnace body, and the gas blown through the slats installed on the side walls and bottom of the furnace body is used for smelting. Stir the iron bath or slag layer in the furnace. This shortens the time for the iron ore, carbonaceous material, lime, etc. to be uniformly mixed in the furnace, promoting the reduction reaction of the iron ore, and stabilizing operations by reducing the frequency of slopping and extending the life of the tuyeres. This makes it possible to reduce manufacturing costs.

The method of dropping iron ore, carbonaceous materials, lime, etc. into the furnace is to uniformly drop it onto the slag surface, or to dump it concentratedly onto the bath surface which is raised by blowing gas from the bottom tuyere. It is much more effective for uniform mixing.

[Example] Embodiments of the invention will be described with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram of the process used in the melt reduction method of the present invention. Iron V611 and a slag layer 12 are formed in the smelting furnace 10, and a first chute 13 into which carbon material and slag material as auxiliary materials are charged is provided at the top of the fRPJ furnace. . The lower part of the first chute 13 is loosely inserted into a through hole 15 provided near the top of the furnace, and the upper part thereof is connected to a charging hopper (not shown) by a flexible joint 16.

Further, an oxygen lance 21 for blowing oxygen is inserted vertically into the furnace. The lances are provided with nozzles 22 and 23, respectively, for injecting oxygen for decarburization and oxygen for secondary combustion. The arrow shown at the tip of the oxygen lance 21 in Figure 1 is 28
．． 29 indicates the direction in which oxygen is blown out for decarburization and for secondary combustion, respectively. A preheating and pre-reducing furnace 30, which is a fluidized bed type reaction device, is provided above the furnace, and iron ore is supplied to this from a second chute 31, and the iron ore that has been preheated and pre-reduced here is passed through the second chute. It is inserted into the smelting furnace 10 through the chute 32 of No. 3. Like the first chute, the third chute 31 is loosely inserted into the through hole 35 and has a flexible joint 36.

A conduit 33 for supplying gas generated from the smelting furnace 10 to the preheating pre-reduction furnace 30 is provided, and a hot cyclone 37 for removing dust from the exhaust gas from the preheating pre-reduction furnace 30 and a conduit 33 for removing dust from the exhaust gas from the preheating pre-reduction furnace 30 are provided. A heat exchanger 38 is provided to obtain steam using heat. Furthermore, the smelting furnace 10
There are tuyeres 25 on the side walls and bottom of the furnace for blowing gas for stirring.
26 are provided respectively.

In addition, in consideration of raw material conditions, equipment costs, ease of operation, etc., a shaft furnace type with good thermal efficiency or a rotary kiln type with reduced equipment costs and easy operation should be installed as the preheating pre-reduction furnace. There is no problem at all in carrying out the present invention.

The operation of the melting reduction apparatus configured as above will be explained. The iron ore is charged from the second chute 31 to the preheating pre-reduction furnace 30, where it is supplied with generated gas from the smelting furnace 10 through the conduit 33, and is preheated and reduced.
It is charged into the smelting furnace 10 through the second chute 81.

Carbon material and slag material, which are auxiliary raw materials, are transferred from a normal charging hopper (not shown) with a simple charging device to a first chute 13.
The smelting furnace 10 is charged through the smelting furnace 10. The first and eighth chutes 13.33 are each loosely penetrated through the through hole 15.35 and have a flexible joint 16.36, so that the direction in which the main raw material and auxiliary raw material are thrown is directed to the smelting furnace 10. , it can be adjusted to the raised area due to the stirring gas blown in from the bottom tuyere above the bath surface. Therefore, the main raw material and the auxiliary raw material are all concentratedly dropped onto the bulge formed by the stirring gas on the bath surface.

The main raw materials and auxiliary raw materials charged into the smelting furnace by being intensively dropped into the swelled portion as described above are stirred by being blown into the tuyeres 25 and 26 provided on the side wall and bottom of the smelting furnace. The slag gas is stirred by the slag gas and quickly and uniformly mixed into the iron bath or slag layer already formed in the furnace. As this stirring gas, an inert gas such as Ar or N2 or an exhaust gas from the preheating pre-reduction furnace, that is, a process gas is used. On the other hand, oxygen supplied from the decarburization and secondary combustion nozzles 22 and 23 of the oxygen lance 21 provides a heat source sufficient to oxidize the carbonaceous material and reduce the iron ore that is the raw material.

Table 1 shows the content of Fe contained in the slag (T-
This figure compares the present invention and a conventional example with respect to Fe) and slopping.

The fact that (T-Fe) is reduced by the method of the present invention indicates that the reduction reaction of iron ore is promoted, and the frequency of occurrence of slopping is clearly reduced by the method of the present invention. It has been shown that In Table 1, the slopping ratio is the ratio of the time during smelting when slopping occurred and the smelting time.

Table 1 [1 Effects of the Invention] According to the present invention, oxygen gas is not blown into the side walls and bottom of the smelting furnace, but an inert or process gas is blown in as the stirring gas, and all the raw materials are Since the raw materials are intensively charged from the top of the smelting furnace toward the swollen part of the bath surface created by the stirring gas from the bottom of the furnace, the charged raw materials are quickly and uniformly mixed in the furnace and the iron ore is reduced. The reaction is promoted, the frequency of slopping is reduced, and the life of the tuyere is extended, which leads to stable operations and reduced manufacturing costs.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the process used in the melt reduction method of the present invention. 10... Smelting furnace, 11... Iron bath, 12... Slag layer, 13... First chute, 15. 35...Through hole, 16,36...Flexible joint, 21...Oxygen
Lance, 22.23,... Nozzle, 30
... Preheating preliminary reduction furnace, 3 1 ... 2nd
Shoot, 32...
Third chute, 33... Conduit, 37... Hot cyclone, 38... Steam generator. Patent applicant Nippon Doppan Co., Ltd.

Claims (3)

[Claims] (1) In a method in which carbonaceous material and oxygen are added to an iron bath in a smelting furnace, and iron ore that has been preheated and prereduced in a preheating prereduction furnace is charged into the smelting furnace to produce hot metal by smelting reduction. Oxygen is blown in from a top-blown oxygen lance that has nozzles for decarburization and secondary combustion, and inert gas or gas generated in the smelting furnace is blown in through tuyeres provided on the side wall and bottom wall of the furnace body. Also, a smelting reduction method characterized in that iron ore, carbonaceous materials, and slag materials are all dropped from above the smelting furnace. (2) The iron ore, carbonaceous material, and slag material are intensively dropped toward the bath surface which is raised by gas injection from the tuyere on the bottom wall of the furnace. Melting reduction method described in Section. (3) The smelting reduction method according to claim 1, wherein the iron ore, carbonaceous material, and slag material are uniformly dropped onto the upper surface of the slag.