JPS6130610A - Method for operating blast furnace - Google Patents

Abstract

PURPOSE:To improve the air permeability of a softening and melting zone in a blast furnace and to reduce pressure loss in the furnace by mixing a prescribed uncoked carbonaceous material with ore and charging the mixture into the blast furnace. CONSTITUTION:The uncoked carbonaceous material contg. <=5% volatile matter is mixed with iron ore to prepare a starting material for a blast furnace. This starting material is charged into a blast furnace, air is sent from a tuyere, and pig iron is discharged. By this method, the air permeability of a softening and melting zone in the blast furnace is improved, pressure loss in the furnace is reduced, and the conditions of the furnace are stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the creation of a method for operating a blast furnace, and it is an object of the present invention to provide a method that enables simple and low-cost operation of a blast furnace with uniform ventilation, low pressure loss, and stable furnace conditions. It is something to do.

Industrial applications How to operate a blast furnace.

Conventional technology Blast furnace operation methods that use coke together with ore have been practiced around the world for a long time. If this thickness is not reached, the layered charging condition will not be maintained properly due to the melting of the ore layer during the process of sinking and reduction melting of the charge in the blast furnace. This is due to the consideration that it will be difficult to obtain stable operation under operating conditions that assume a stratified charging state.

Problems to be Solved by the Invention However, it is generally said that in the case of the conventional method such as the 7t described above, there is a considerable pressure loss due to the injection of hot air into the blast furnace, and the Therefore, the operating power cost of the blower blower, etc. must be extremely high, and if there is a part of the charge layer that is easily ventilated, that part will be concentrated. It is not easy to ventilate air from the inside of the furnace to make the air uniform inside the furnace, and it is also difficult to obtain favorable results regarding operating conditions such as the reduction reaction inside the furnace, gas utilization rate, and fuel ratio. It's difficult to do. The above-mentioned carbon material to be introduced into the blast furnace should be metallurgical coke that has been subjected to a coking process for a considerable period of time. It is necessary to crush this material into a coke oven and coke it, then cool the charred material, then crush it again and classify it to a particle size suitable for charging into a blast furnace. However, these processes are expensive both in terms of energy and man-hours, and the losses during these steps are also large, which is disadvantageous in terms of yield. In particular, it is well known that the above-mentioned coking process is not favorable in terms of the working environment, and for this reason, in recent years, dry-type cooling has been adopted instead of conventional water injection cooling for coke discharged from red-hot kilns. Although cooling technology has been adopted, the working environment is not necessarily sufficient, but the time required for the work process and the equipment required to obtain the desired coke are large, resulting in increased costs. I don't get a 5. The processing costs to obtain this coke and the reduction in yield during the coking process, along with the power costs for operating the blower for blowing hot air mentioned above, ultimately have an impact on blast furnace operating costs and tapping costs. This cannot but be an important factor in the rise in steel manufacturing costs.

``Structure of the Invention'' Means for Solving the Problems The present invention has been devised after repeated studies in view of the above-mentioned unfavorable circumstances. This blast furnace operating method is characterized in that, in order to tap iron by blowing air through the tuyeres, carbonaceous material having a volatile content of 5% or less and not subjected to coking treatment is mixed with the iron ore and charged.

By mixing iron ore and carbonaceous material and charging the mixture into the blast furnace, the ventilation condition of the softened and molten zone in the blast furnace is improved, making it possible to operate the blast furnace uniformly and with little pressure loss. Therefore, it is not necessary to specifically coke the carbonaceous material, and it becomes possible to use the carbonaceous material with a volatile content of 5% or less without undergoing a complete coking process. The use of carbonaceous materials is difficult and complicated for coking,
Eliminate the need for environmentally undesirable work. Air blowing with low pressure loss reduces the power cost for the air blowing, and together with the use of carbonaceous material that does not require coking as described above, it brings about sufficient cost and energy savings. The carbonaceous material may be in the form of small particles of 10111 or less.

EXAMPLE To specifically explain the invention according to the above-mentioned invention with further appropriate reference to the attached drawings, the present inventors used sintered ore of 51111 or more and coke according to the above-mentioned conventional method. (sintered ore) 55Qw, coke-”t
Each layer thickness of 500 mu was charged and formed alternately from the top of the furnace.
Figure 1 shows the results of detailed measurements of the pressure loss in each temperature range in the furnace where hot air is blown from the tuyere.
This 12
When the temperature exceeds 00℃, the pressure loss increases rapidly, and the temperature rises to 1400℃.
A peak point exceeding 400wH,O is shown in the front and rear bands, and in the temperature range above that, the pressure loss decreases again, reaching several tens of IIIH,0 at about 1600°C.

Of course, the specific values and peak point positions for the pressure drop as mentioned above vary depending on the quality of the ore used, such as the reduction rate. The pressure loss value at the peak point is 300 to 700 wH, 0
Even if it falls within the range of , the general situation will be as shown in FIG. However, when we consider the reason why the pressure drop suddenly increases when the temperature exceeds 1200℃ as mentioned above, we find that in the above temperature range, the ore softens and melts, and the ore layer shrinks. Furthermore, the molten metal flowed down and penetrated into the coke layer, and it is recognized that both of these causes the voids yJ that had been obtained between the particles of the charging layer to become clogged. Moreover, such void occlusion is 1,500 to 1
．． When the temperature reaches a zone of 600° C., the metal component is separated from the coke layer in a downstream manner, and the coke layer becomes almost exclusively present, and the pressure loss is reduced again.

Therefore, the inventors of the present invention have repeatedly studied and speculated on how to eliminate the above-mentioned pressure loss peak point, and as an example, they charged a mixture of ore (sintered w) and coke gold at an equal volume ratio. The pressure loss was measured in each temperature range in the same manner as in Fig. 1, and the results are shown in Fig. 2.The pressure loss peak point around 1400°C was almost completely eliminated, and the pressure loss was measured at several tens of wH in the entire temperature range. , 0 or less, and it was found that the ventilation condition became uniform and the furnace condition and other conditions became stable and good.

However, by changing the ventilation conditions in the furnace as described above, especially 1.
It is assumed that it is not necessarily necessary to use a coked material as the carbon material if pressure loss (i.e. ventilation conditions) in a high temperature zone such as 200°C or higher is improved. In view of the above technical relationship, the present invention was completed after careful consideration of the use of a carbonaceous material that does not form coke, in accordance with the above-mentioned method of completely mixing and charging iron ore and carbonaceous material. In other words, if the carbonaceous material used for this purpose has a high Fi volatile content, this volatile content will be diffused from the raw material charged into the blast furnace, and this method is used in the blast furnace gas cleaning system that is common today. inhibit the function of However, the degree of content of such volatile matter has to be considered. Although the amount of the carbonaceous material blended depends on the result, generally speaking, if it is less than 5%, it is used by mixing it with ore such as sintered ore. It was confirmed that the amount of volatilization in the blast furnace gas was small and that it could be implemented without impairing the functions of the electrostatic precipitator in the blast furnace gas cleaning system.

Examples of the above-mentioned charcoal materials having a volatile content of 5% or less include anthracite from Vietnam, Samshindong charcoal from North Korea, and charcoal.

A specific example of the operation of the apparatus according to the present invention as described above will be explained as follows.

Operation example 1 Hongay coal from Vietnam (V, M = 4.2%) 8-25
Cod material is used as charcoal material, while iron ore is 8-251
Using 01 blending ore and 5-50m sintered ore,
A mixture of such carbonaceous material and iron ore with an ore/charcoal material ratio (0/C)' of 2.20 was charged into a blast furnace, and hot air at 1100°C was blown at 2.5 kg/cdl from the tuyere. Blow operation was carried out under pressure.

The pressure loss peak point in the temperature range of 1300 to 1400°C in the furnace is 60wH! It was confirmed that the volatile content in the blast furnace gas recovery system was 40 PI)m and that there was no problem with the operation of the electrostatic precipitator. Furthermore, even when the mixing ratio of Hongei coal and coke was set to 2=1 in electric ratio, the volatile content of the blast furnace gas recovery system was 50 pl)m, and stable operation could be achieved in the same way.

Operation example 2 Samshindong coal (V, M = 2%) from North Korea with 8 to 25 liters is used as coal material, while iron ore is blended ore with 8 to 251 EL and sintered ore with 25 to 75 EL. A mixture of carbonaceous material and iron ore with an ore V-charcoal material ratio (0/C) k2.20 was charged into a blast furnace, and hot air at 1100°C was blown through the tuyere at a pressure of 2.5ky/cIlt. Blow operation was carried out.

The pressure loss peak point in the temperature range of 1300 to 1400°C in the furnace is 40 + a + H20, which allows stable blast furnace operation, and the results of measuring the volatile content in the blast furnace gas recovery system are 351) I) m As in Operation Example 1, there was no problem with the operation of the electrostatic precipitator, etc.

Operation example 3 Charcoal (V, M = 0.2%) (D 8-25
trim) as carbonaceous material, while iron ore is 8
Using ~25 tons of blended ore and 25 to 75 tons of sintered ore, such carbonaceous materials and iron ore gold ore/charcoal materials ratio (0/C
) The mixture as t2.10 is charged into a blast furnace, and hot air e2.2kl of 1100℃ is emitted from the tuyere. The blowing operation was carried out at a pressure of /-.

The pressure loss peak point in the temperature range of 1300 to 1400°C in the furnace was 70 MH,O, allowing stable blast furnace operation, and the volatile content in the blast furnace gas recovery system was measured at 30 ppm. The fact that there is no problem in the operation of the electrostatic precipitator, etc. is the same as in operation example 1.2, that is, in this case, no coke was used at all, but a preferable blast furnace operation is possible. It was confirmed.

``Effects of the Invention'' According to the present invention as explained above, I improves the ventilation properties of the softened molten zone in the blast furnace by charging a mixture of carbonaceous material and ore, which is advantageous in that it is uniform and has low pressure loss. It enables blast furnace operation, does not require coking as the above-mentioned carbonaceous material, and uses carbonaceous material with a volatile content of 5% or less without undergoing coking treatment, which is extremely complicated for Ericoke treatment. In addition, it eliminates the need for processing work that is unfavorable in terms of the working environment, and as mentioned above, the low pressure loss reduces the power cost for blowing air, making it a sufficiently low-cost, low-energy blast furnace. It is clear that this invention is capable of realizing all operations and is industrially highly effective.

[Brief explanation of drawings]

The drawings show the technical content of the present invention; Figure 1 is a chart showing the pressure loss relationship in each temperature range in conventional blast furnace operation, and Figure 2 is a diagram showing the carbon material and ore mixing equipment of the present invention. Entering 1
FIG. 2 is a diagram showing relationships similar to FIG. 1 for examples; FIG.

Claims (1)

[Claims] When charging iron ore and carbonaceous materials as raw materials into a blast furnace and tapping the iron by blowing air from the tuyeres, carbonaceous materials with a volatile content of 5% or less and which are not subjected to coking treatment are mixed with the iron ore. A blast furnace operating method characterized by charging.