JPH049413A - Method for charging hard-to-reduce ore into blast furnace - Google Patents

Abstract

PURPOSE:To suppress an increase in fuel ratio even if the substitution rate to substitute a hard-to-reduce ore with a sintered ore is increased by charging the hard-to-reduce ore into the central part of a blast furnace. CONSTITUTION:The hard-to-reduce ore having <=30% reducibility is charged into the central part of the blast furnace for the hard-to-reduce ore in the method for charging the above-mentioned hard-to-reduce ore into the blast furnace. The range where the hard-to-reduce ore is charged may be confined to 3/4 of the in-furnace radius of the stock line. The increase in fuel ratio is effectively prevented and, therefore, a good result is obtd. if the hard-to-reduce ore is substituted with the sintered ore and is charged into the central part of the blast furnace and the substitution rate thereof is confined to <=20%.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to a method of charging a refractory ore into a blast furnace that can suppress an increase in fuel ratio.

[Prior art] The charging of refractory ores (Romeral, etc.) into the blast furnace is
Because this leads to an increase in the ratio, it is not often used, and when it is used, the blending ratio is set to 10-6 or less. Japanese Patent Application Laid-Open No. 62-224606 is a published technique for using refractory ores in blast furnaces. This is done by crushing the hard-to-reducible ore, turning it into powder, and injecting it into the furnace through the blast furnace lining. The aim is to stabilize the furnace condition by preventing the occurrence of this, and also to prevent the fuel ratio from increasing.

“Problems to be Solved by the Invention” However, there is a problem in that crushing the refractory ore into powder increases the cost of pig iron9. The purpose is to provide a charging method.

[Means for Solving the Problems] The present invention aims to achieve the above objects,
A method for charging a refractory ore into a blast furnace in which a refractory ore with a reduction rate of 30% or less is charged into a blast furnace, characterized by charging the refractory ore into the center of the blast furnace. This is a method of charging ore into a blast furnace. In this case, the range in which the refractory ore is charged may be 3/4 of the stock line furnace radius from the furnace center.

Furthermore, it is preferable to charge the hard-to-reducible ore into the center of the blast furnace in place of the sintered ore, and to set the replacement rate to 20% or less, since this can effectively prevent an increase in the fuel ratio.

[Function] When charging a part of sintered ore with ore, conventionally a mixture of sintered ore and ore is poured from the center of the furnace to the furnace wall on top of the coke layer 1, as shown in Fig. 3. It was charged so that the layer thickness was uniform throughout. In this case, as the substitution rate with sinter is increased, the reduction rate (represented by R1) is
Compared to normal ores with RI of 50% or more, as the conversion rate of refractory ores with RI of 30% or less is increased, the difference in fuel ratio increase (not expressed in dFR (kg/l)) becomes larger. Become.

On the other hand, when a refractory ore with an RI of 30% or less is charged into the center of a blast furnace, the reduction potential in the center becomes high;
If the substitution rate is 20% or less, as shown in Figure 2, R
There is no difference compared to when replacing with 150% or more normal ore.

[Example] The method of the present invention will be explained in detail below. The inventors determined that, depending on the increase in fuel ratio (ΔFR%) due to the charging of hard-to-reducible ores (RI 30% or less), the difference from JFR% in the case of normal ores (R 150% or more) increases as the substitution rate increases. In order to prevent this from becoming too large, various aspects were considered. During this study, we focused on the fact that the reduction potential at the center of the blast furnace was greatest based on the gas flow and Co gas concentration distribution in the blast furnace, and we considered charging the refractory ore to the center of the furnace. Figure 1 schematically shows the cross section of the top charge when raw materials are charged using this method. Ore 3 is charged, and ordinary ore 2 shown in Table 1 is charged around the furnace wall. The charging range of the hard-to-reducible ore should be within 0.75H from the center of the furnace, where R is the inner radius of the stock line.The hard-to-reducible ore is replaced with the sintered ore, and the replacement rate is Increase, then the fuel ratio increases! (ΔFR%) was investigated. Figure 2 shows the results. In Figure 2, for comparison purposes, draw a correlation line when a refractory ore is charged using the conventional method.

In the case of the method of the present invention, AFR% has a conversion rate of 20%.
Up to 30% is the same as normal ore, and when the replacement rate exceeds 20%, the increasing slope of -FR% becomes large.
ΔFR when reducible ore is charged using the conventional method
It turns out that the percentage is the same.

Table 1 [Effects of the Invention] Since the present invention is purified as described above, even if difficult-to-reducible ores with a reduction rate of 30X or less are charged and used by changing the charging method, the fuel ratio It has the effect of making the increase in the amount similar to that of normal ore.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the method of the present invention, Fig. 2 is a graph showing the relationship between the substitution rate of sintered ore and aFR% by the method of the present invention, and Fig. 3
The figure is an explanatory diagram of the conventional method, and FIG. 4 is a graph diagram showing the relationship between the replacement rate of sintered ore and AFR% according to the conventional method. 1...Coke layer, 2. Ordinary ore layer, 3. Difficult to reduce ore layer.

Claims (3)

[Claims] (1) A method for charging a refractory ore into a blast furnace in which a refractory ore with a reduction rate of 30% or less is charged into a blast furnace, characterized by charging the refractory ore into the center of the blast furnace. A method of charging refractory ore into a blast furnace. (2) In the method of charging difficult-to-reducible ores into a blast furnace, in which hard-to-reducible ores with a reduction rate of 30% or less are charged into blast furnaces, hard-to-reducible ores are replaced with sintered ores and charged into the center of the blast furnace. A method for charging refractory ore into a blast furnace, characterized in that the replacement rate is 20% or less. (3) Claim 1 or Claim 2, wherein the refractory ore is charged within a range of 3/4 of the radius of the stock line furnace from the center of the furnace.
A method for charging the described refractory ore into a blast furnace.