JPS6335728A - Method for charging powder ore to smelting and reducing furnace - Google Patents

Abstract

PURPOSE:To charge powder ore at a high addition efficiency to a furnace and to obtain a high reduction speed by forming a horizontal part to the side wall of the furnace body and blowing the powder ore perpendicularly downward from a blow port provided to the horizontal part into a metal bath. CONSTITUTION:Part of the side wall of a vessel 2 is formed to the horizontal part 14 and the blow port 15 directing perpendicularly downward is provided to the horizontal part 14. The powder ore is blown perpendicularly downward from the blow port 15 into the metal bath 8. The metal oxide contained in the powder ore in contact with the metal bath 8 is reduced to a metal state by the carbon in the metal bath 8 and is migrated into the metal bath 8. The powder ore blown at this time flows by riding the circulative flow of the metal bath and makes the contact reaction with the metal bath 8 in the long stagnation time. Smelting and reduction are executed with high productivity by the above-mentioned method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of charging fine ore so as to obtain high reduction efficiency when melting and reducing oxide ore.

[Conventional technology]

Recently, smelting reduction smelting has been the focus of attention as a steelmaking technology that replaces blast furnace and converter methods. The smelting reduction furnace used in this method was developed for the purpose of producing molten iron-based alloys using smaller-scale equipment without being restricted by the raw materials used.

As one of such melting reduction furnaces, the present inventors previously proposed a furnace of the type shown in FIG.
No. 95). This furnace includes a fixed vertical furnace section 1 and a container section 2 that is detachably attached to the vertical furnace section 1. The container part 2 is placed on a trolley 3, and another container part 2
This allows for easy exchange.

The container section 2 mainly contains a molten material such as a metal bath 8, and has a bottom blowing tuyere 11 provided on the bottom wall for blowing oxygen gas and fuel such as propane, pulverized coal, etc. into the molten material. The gas blown into the -CC container section through the bottom blowing tuyere 11 rises in the metal bath 8 as bubbles 10, and proceeds with the reduction reaction of the charged raw material.

Further, a tap hole 12 is provided in the lower part of the container portion 2, and molten materials such as molten metal and slag are discharged out of the furnace through the tap hole 12 at any given time.

On the other hand, the vertical furnace section 1 has a vertical cylindrical shape or a cylindrical shape with a partially enlarged diameter. The lower part of the vertical furnace part 1 is attached to and detachable from the container part 2, and the upper part is connected to a duct for sending the exhaust gas 13 to the exhaust gas utilization system. The lower part of the vertical furnace section 1 is partially immersed in a formed slag layer 9.

A lance 4 and a plurality of lances 5 are inserted into the vertical furnace section 1 from vertically above and from diagonally above or laterally. Gas such as oxygen gas and/or powder such as ore 3 coal is blown into the furnace from these lances 4 and 5.

Furthermore, this vertical furnace part l is provided with a lump charging device 6 for charging lumps such as ore or its molded material, lump carbonaceous material, etc., and this lump charging device 6 is connected to a screw feeder 6a. It is equipped with °C.

In this smelting reduction furnace, the slag layer 9 in which carbonaceous material is suspended is brought into sufficient contact with the metal bath 8 to promote the smelting reaction at the interface. Also, slag N
9, the reaction of C+ FeO→Fe + Co is performed. Therefore, it is important to devise ways to charge the ore raw material into the slag layer 9.

[Problem that the invention seeks to solve]

The form of ore raw materials used in smelting methods other than smelting-reduction methods has been considered primarily with ease of charging in mind. On the other hand, in the smelting reduction method, as mentioned above, unlike the conventional smelting reaction, the reaction mainly occurs at the interface between the molten metal and the slag, and the reaction requires a certain amount of heat. I need.

However, when fine ore is introduced from above the bath surface, a large proportion of the fine ore is consumed in the falling process, and the probability that the fine ore reaches the interface between the molten metal and slag is low.For example,
It is accompanied by the exhaust gas rising in the furnace and cannot be efficiently added to the reaction zone. Furthermore, when fine ore is injected from the bottom of the furnace through the bottom blowing tuyeres, the charged fine ore may blow through together with the gas, making it impossible to obtain sufficient residence time. There is a limit to increasing the addition efficiency even by blowing. Furthermore, blowing through the bottom blowing tuyeres makes maintenance difficult.

This problem regarding the addition of fine ore is not limited to the vertical dispersion type smelting reduction furnace as shown in Figure 4.
For example, this is common to various other types of melting reduction furnaces, such as the converter type.

Therefore, an object of the present invention is to provide a smelting reduction method in which fine ore can be charged with high addition efficiency and a high reduction rate can be achieved by improving the charging form of fine ore.

[Means for solving problems]

In order to achieve the purpose of the fine ore charging method of the present invention,
When melting and reducing oxide ores mainly through the interfacial reaction between molten metal and slag, a furnace with a side wall of the furnace body with a horizontal section formed below the surface of the metal bath is prepared, and the powdered ore is transferred to the horizontal section. It is characterized by blowing vertically downward into the metal bath from the blowing port provided in the metal bath.

In addition, Gogo's term for powdered ore includes those that have been pre-reduced.

[Effect]

Powdered ore has a large specific surface area, so it is highly reactive to slag, and when pre-reduced powdered ore is used, it is reduced and transferred to the molten metal bath in a short period of time. do.

However, with the usual addition method, it is not possible to obtain the efficiency of addition as described above.

Therefore, in the present invention, this fine ore is directly blown vertically downward into the metal bath from a horizontal portion provided on the side wall of the furnace body. FIG. 1 shows an example of such blowing. The example shown in FIG. 1 mainly shows the container section 2 of the upper and lower separated type melting reduction furnace shown in FIG. 4.

However, the present invention is not limited to this, and can of course be applied to other types of melting reduction furnaces.

A part of the side wall of the container part 2 is formed into a horizontal part 14, and the horizontal part 14 is provided with an inlet 15 directed vertically downward.

In the example shown in FIG. 1, the horizontal portion 14 is formed over the entire circumference of the side wall of the container portion 2. However, it is also possible for the side wall of the container part 2 to partially protrude inwardly and form a plurality of horizontal parts 14 there. Further, the horizontal portion 14 is not limited to being provided at exactly right angles to the vertical side wall portion 16.
Considering the behavior of the fine ore blown in, the angle formed by the horizontal part 14 and the vertical side wall part 16 should be in the range of 60 to 90 degrees. When the inlet 15 is provided at right angles to the wall, the angle of the inlet 15 with respect to the perpendicular is 0 to 30 degrees. In this specification, the direction of the fine ore that is blown in at this angle is
In a practical sense, it is vertically downward.

The distance by which the horizontal portion 14 projects inward of the furnace body is preferably set so that the fine ore injected from the inlet 15 does not come into direct contact with the vertical side wall portion 16 . for example,
When the inner diameter of the container part 2 is 200On+ and the height H from the bottom of the furnace to the horizontal part 14 is 1000 m, the horizontal part 14
Take the length of 200 dragons. Then, the air inlet 15,
It is provided at about 100 degrees from the inner surface of the vertical side wall portion 16.

When fine ore is injected from the inlet 15 provided in the horizontal portion 14, the ore becomes a downward flow 17 and enters the metal bath 8. The metal oxide contained in the fine ore that has come into contact with the metal bath 8 is reduced to a metallic state by the carbon in the metal bath 8 and transferred to the metal bath 8. This reduction reaction generates gases such as Co and COz, and when the fine ore is heated in the metal bath 8, gases such as 11□0 are generated.

These gases and the carrier gas used to blow the ore create a circulating flow in the metal bath 8 as indicated by the arrows. That is, the fine ore rides on this circulating flow and comes into contact with the metal bath 8 to react. For this reason,
For example, compared to the case of blowing from the bottom blowing tuyere, the contact time with the metal bath 8 is twice as long as the time during which the metal bath 8 is on the downward flow 17 and the time during which it is on the upward flow by simple calculation.

Since the residence time is thus long, excellent reaction efficiency can be obtained as shown in FIG. 2. In addition, in FIG. 2, the reaction efficiency is expressed by the reaction rate constant obtained by the experiment shown in the example.

In addition, when fine ore is injected from the inlet 15 provided in the horizontal part 14, the fine ore passes through the metal bath 8 and reaches the outside of the reaction system, as seen in conventional bottom blowing, so-called blow-through. will no longer occur. Therefore, the yield of charged fine ore is excellent. Figure 3 shows
The graph shows the charging yield of fine ore corresponding to this difference in charging method. As is clear from this figure, in the case of the bottom blowing method of the present invention, most of the charged fine ore is used for the reduction reaction.

Further, it is preferable that the blowing port 15 be provided at a relatively shallow part of the metal bath 8. When the inlet 15 is provided at such a location, the head of the metal bath 8 that is connected to the inlet 15 also becomes small. Therefore, the pressure of the carrier gas required for blowing can be lowered compared to the case of bottom blowing, and maintenance of the blowing port 15 is also facilitated.

[Example〕 Hereinafter, the features of the present invention will be specifically explained with reference to Examples.

The melting reduction furnace used in this example has an inner diameter of D=2000 mm in FIG. 1, a height of H=1000 mm from the bottom of the furnace to the horizontal part 14, and a length of the horizontal part 14 of L"200+n. Let the angle formed by the horizontal part 14 and the vertical side wall part 16 be a right angle, and from the inner surface of the vertical side wall part 16 10
A furnace having an internal volume of 30 tons and having an air inlet 15 at the zero point was used.

In this furnace, 20 tons of hot metal, CaO2 as flux,
7 tons, 1.8 tons of SiO□, and 1.2 tons of coke were charged, and top-blown oxygen was heated at 600 ON n? Oxygen gas was blown into the furnace at a rate of 7 o'clock and bottom-blown oxygen of 40 ONm/hour.

In addition, the air inlets 1 provided at a total of 3116 locations in the horizontal portion 14
5 to 200ON of nitrogen gas each! 15 kg/min of fine ore with a particle size of less than 1 mm using carrier gas.
On the other hand, coke was blown in at a rate of 8 min.
It was fed at a rate of 0 kg/min.

When smelting continued for one hour, 9 tons of hot metal was obtained. The ore yield at this time was 99%, and the reaction rate was 1
00 kg-Fe/min (XT, Fe1l).

〔Effect of the invention〕

As explained above, in the present invention, the tuyere for injecting fine ore is provided on the horizontal part of the side wall of the furnace body, and by blowing the fine ore vertically downward to the metal bath, the blown ore powder is transferred to the metal bath. It flows along with the circulating flow of the bath and comes into contact with the metal bath for a long residence time. Therefore, it has become possible to charge fine ore with a high yield and excellent reaction efficiency. Therefore, according to the present invention, melt reduction can be carried out with high productivity.

[Brief explanation of drawings]

FIG. 1 shows the main parts of a smelting reduction furnace equipped with a fine ore injection tuyere in an embodiment of the present invention, and FIG. The figure also shows the yield corresponding to the difference in the charging form of fine ore. Also,
FIG. 4 shows a melting reduction furnace previously developed by the present inventors.

Claims (1)

[Claims] 1. When melting and reducing oxide ores mainly through the interfacial reaction between molten metal and slag, a furnace with a side wall of the furnace body with a horizontal section formed below the metal bath surface is prepared, and powdered ore is melted and reduced. A method for charging fine ore into a smelting reduction furnace, characterized in that fine ore is blown vertically downward into the metal bath from an inlet provided in the horizontal part.