JPS6335731A - Method for charging ore to smelting and reducing furnace - Google Patents

Abstract

PURPOSE:To charge ore with high addition efficiency to a furnace and to obtain a high reduction speed by dividing the ore to be charged at the time of smelting and reducing oxide ore to massive, small granular and powder ores and charging the ores by an adequate method meeting the respective grain sizes. CONSTITUTION:The ore to be charged to the furnace at the time of smelting and reducing the oxide ore by the interfacial reaction of a molten metal and slag is divided to the massive, small granular and powder ores. The massive ore is charged into the furnace from above and the small granular ore is charged therein from plural bottom blowing tuyeres 11 by using a carrier gas. The powder ore is charged into the furnace from plural side facing tuyeres 14 provided on the furnace wall by using a carrier gas. Since the powder ore is charged into the furnace so as to be orthogonal with the circulating flow of the molten metal circulating perpendicularly in the furnace, the powder ore contacts a metal bath 8 with the satisfactory stagnation time. The high reaction rate is obtd. and the 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 provides a method for melting and reducing oxide ores by adopting an optimal charging form depending on the particle size of the ore.
This invention relates to an ore charging method that achieves high yield and reduction efficiency.

[Conventional technology]

Recently, the smelting reduction smelting method has been attracting attention as a steelmaking technology to replace the blast furnace/converter method. 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. 5 (Japanese Patent Application No. 61-228).
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 a on the trolley 3, and another container part 2
This allows for easy exchange.

The container section 2 mainly contains a molten material consisting of a metal bath 8, etc., and has a bottom blowing tuyere 11 provided on the bottom wall for blowing oxygen gas and fuel such as propane, charcoal, etc. into the molten material. There is. The gas blown into the container part 2 through the bottom blowing tuyere 11 flows through the metal bath 8. mlO and rises to advance the reduction reaction to the charged raw material.

Further, an easy-to-draw outlet 12 is provided at the lower part of the container part 2, and 't' can be accessed at any time through this outlet 12. Molten metal, slag, and other molten materials are discharged from the IJF furnace.

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. From these lances 4 and 5, gas such as oxygen gas and/or bodies such as ore (9) and coal are blown into the furnace. Further, 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

In this smelting reduction furnace, the slag N9 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, in the slag layer 9, a reaction of C+ FeO→Fe+CO takes place. 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 introducing powdered ore from above the bath surface,
A large proportion of the powdered ore is consumed during the falling process, and the probability that the powdered 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. Can not. Furthermore, when powdered ore is blown from the bottom of the furnace through the bottom blowing tuyere, the charged powdery ore may blow through together with the gas, making it impossible to obtain a sufficient residence time. Therefore, there is a limit to increasing the addition efficiency even with this bottom blowing.

This problem regarding the addition of powdered ore is not limited to the upper and lower separated type smelting reduction furnace as shown in Figure 5, but also applies to various other types of smelting reduction furnaces such as the converter type. They are common.

On the other hand, lumpy ores have a good yield due to less scattering loss, but have a small specific surface area and low reactivity. Therefore, in order to efficiently carry out the reduction reaction of this lumpy ore, it is necessary to charge it so that it comes into sufficient contact with the slag N9 and the metal bath 8. Further, small-grain ore has properties intermediate between powder ore and lump-like ore, and requires a feeding method that is appropriate for these properties.

Therefore, the present invention charges ores with high addition efficiency by adopting an optimal charging method according to the ore particle size for each of these lump-like, small-grained, and powdered ores. The purpose of this invention is to provide a smelting reduction method that can increase the reduction rate.

[Means for solving problems]

In order to achieve the objective, the ore charging method of the present invention mainly uses the interfacial reaction between molten metal and slag to melt and reduce the oxide ore, and the ore to be charged is divided into lumps, small particles, and powder. The feature is that the lumpy ore is directly charged from the top, the small granular ore is blown from the bottom of the furnace through the bottom blowing tuyere, and the powdered ore is blown sideways through the tuyere provided on the side wall of the furnace body.

In this specification, ore is used to include pre-reduced ore, and lump ore is also used to include briquettes of bulk ore.

[Effect]

Powdered ore has a large specific surface area, so it is highly reactive to slag. Also, this powdered ore
When using pre-reduced metal, it will be reduced and transferred to the molten metal bath for a short period of time. However, with the usual addition method, the addition efficiency cannot be obtained as described above. Therefore, we adopted a method of blowing this powdered ore horizontally into the metal bath. When this blowing method is used, blow-through as seen in the bottom blowing method does not occur, and a sufficient stirring action can be exerted on the metal bath.

On the other hand, since lump ore has a good addition yield, it is directly added from the top. This input lump ore dissolves (in the process of falling through the slag layer) and reacts with the carbon material suspended in the slag layer. It also reaches the slag-metal interface and continues to undergo a reduction reaction.

Regarding small granular ore, since the yield rate and reaction rate were poor when charging from the top, a charging method using bottom blowing was adopted. This small granular ore has a certain degree of particle size, so even if it is blown in by the bottom blowing method, it will not blow through unlike powdered ore. Further, by combining with side blowing, even more sufficient stirring action can be obtained.

FIG. 1 shows the main parts of a /8 smelting furnace used to carry out the ore input method of the present invention. In FIG. 1, parts corresponding to those shown in FIG. 5 are designated by the same reference numerals.

The lump ore is charged into the furnace from a lump charging device 6 shown in FIG. Incidentally, it is preferable that the lumpy ore fed from the lumpy material feeding device 6 has a particle size of more than 1 mm. When ore with a particle size smaller than this is charged at the top, a large proportion of the ore is entrained in the gas rising in the furnace, resulting in a decrease in yield.

The small granular ore is blown into the furnace through a bottom blowing tuyere 11 provided at the bottom of the furnace on a carrier gas such as nitrogen gas. When the particle size of this small-sized ore is preferably 0.25 to 1+n and the zero particle size becomes 0.25 m<2> or less, the proportion of the small-sized ore passing through the metal bath 8 and the slag layer 9 by blow-through increases. On the other hand, when the particle size exceeds one grain, the blowing becomes more efficient.

The powdered ore is then transported through the horizontal tuyere 1 installed on the side wall of the furnace body.
Blow in from 4. The particle size of this powdered ore is 1
The particle size is less than 0.25 m and is not suitable for blowing from 1. The powdered ore injected from the horizontal tuyere 14 is charged perpendicularly to the molten metal flow that circulates vertically in the furnace, so it does not rise immediately after being blown and is sufficiently retained. Contact with the metal bath 8 after some time. In other words, the blowing from the bottom blowing tuyere 11 creates a circulating flow of molten metal in the metal bath 8 that rises at the center of the furnace and falls around the periphery of the furnace. Powdered ore will be added to the descending portion of this circulation stream. Therefore, the powdered ore once descends and then ascends, thereby further increasing the yield and reaction efficiency.

In addition, in the present invention, when maintaining the ore charging ratio at lump ore: small granular ore: powder ore - 1:0.5 to 2:0.5 to 2, the characteristics of ore of each particle size can be fully demonstrated, and an efficient melting reduction method can be carried out. When the ore charging ratio is maintained within this range, the action of the lumpy ore that stays at the slag-metal interface to generate gas and stir the interface, the action of the small granular ore that stirs the metal bath 8 by bottom blowing, and The stirring action of the powdered ore by side blowing produces an optimal synergistic effect.

In FIG. 1, the present invention is explained using an example in which the present invention is applied to the container section 2 of the upper and lower separated type melting reduction furnace shown in FIG. However, the present invention is not limited to this, and can of course be applied to other types of melting reduction furnaces, such as a converter type.

〔Example〕

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

In a smelting reduction furnace having the structure shown in Fig. 1, 20 tons of hot metal, Ca02.7) as flux, and 5 iOz 1.
8 tons of coke and 1.2 tons of coke were charged, and oxygen gas was blown into the furnace at a rate of 6000 Nm/hour of top-blown oxygen and 40 ONm/hour of bottom-blown oxygen.

Blocked ore with a particle size exceeding l a@ is handled by the block loading device 6.
The amount of water was added at a rate of 50 kg. In addition, the particle size is 0.
Small granular ore of 25 to 1 carbonate was injected from bottom blowing tuyeres 11 provided at five locations on the bottom of the furnace at a rate of 10 kg/min using 200 ON l/min of nitrogen gas as a carrier gas.

Powdered ore with a particle size of less than 0.2sa
0 ON l/min was used as a carrier gas, and 10 kg/min was added at a rate of 10 kg/min. On the other hand, coke was used as a carbon material at 80%
It was added at a speed of kgZ.

When smelting continued for one hour, 6 tons of hot metal was obtained. The ore yield at this time was 96%, and the reaction rate was 9.
The ore yield at this time, which was 5 kg-pe/min (χT, Fe), is shown in the second table according to each charging method.
-Figure 4.

As is clear from these figures, lumpy ore is suitable for charging from the top, small granular ore is suitable for charging by bottom blowing, and powdery ore is suitable for charging by side blowing. In addition, in the case of side blowing, the yield of small granular ore and powdered ore is almost the same. However, since the metal bath 8 also has a stirring function for small granular ore, charging by bottom blowing is adopted.

〔Effect of the invention〕

As explained above, in the present invention, the charging form of ore is changed depending on the particle size, so there is less loss due to blowholes, etc., and the yield of ore is excellent.

In addition, the metal bath is sufficiently stirred by bottom blowing,
Since the powdered ore is blown into the downward flow of the metal bath from the side, the powdered ore comes into contact with the metal bath for a sufficient residence time of one hour. Therefore, the reaction rate is also excellent. In this way, according to the invention, smelting reduction can be carried out with great productivity.

[Brief explanation of the drawing]

FIG. 1 shows an example in which the present invention is applied to a vertically separated type smelting reduction furnace, and FIGS. 2 to 4 show the yield of ore in this example. Further, FIG. 5 shows a top-bottom separation type melting reduction furnace that was 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, the ore to be charged is divided into lumps, small particles, and powder, and the lump ores are charged directly from the top.
A method for charging ore into a smelting reduction furnace, characterized in that small granular ore is blown from the bottom of the furnace through a bottom blowing tuyere, and powdered ore is blown sideways through a tuyere provided on the side wall of the furnace body.