JPH0365402B2 - - Google Patents

Description

[Detailed Description of the Invention] "Object of the Invention" The present invention relates to the creation of a blast furnace operating method, which enables simple and low-cost operation of a blast furnace with uniform ventilation, low pressure loss, and stable furnace conditions. It is intended to provide a method.

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 known that in the case of the conventional method as described above, there is a considerable pressure loss when hot air is blown into the blast furnace. Therefore, the operating power cost of the blower, etc. must be enormous, and if there is a part of the charge layer that is easily ventilated, the air will be concentrated away from that part. It is not easy to ventilate and uniformize the air flow inside the furnace, and it is also difficult to obtain favorable results regarding operating conditions such as the reduction reaction within the furnace, gas utilization rate, and fuel ratio, and there is also insufficient stabilization of operation. hard. It should be noted that the above-mentioned carbon material to be fed into the blast furnace should be metallurgical coke that has been subjected to a coking process for a considerable period of time. This product is crushed to a particle size suitable for charging into a blast furnace, then charged into a coke oven for coking treatment, and then taken out of the kiln, cooled, and then crushed again to size and classify to a particle size suitable for charging into a blast furnace. These processes are enormous in terms of both energy and man-hours, and 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 cooling has been adopted instead of conventional water injection cooling for cooling the coke discharged from the red-hot kiln. Although new technology has been adopted, the working environment is not always sufficient, and the time required for the work process and the equipment required to obtain the desired coke are becoming large, leading to increased costs. The processing costs to obtain these cokes, the yield loss during the coking process, etc., along with the blower operating power costs for blowing hot air mentioned above, ultimately have an impact on blast furnace operating costs and tapping costs. This cannot help but be an important factor in the rise in steel manufacturing costs.

"Structure of the Invention" Means for Solving the Problems The present invention was devised after repeated studies in view of the above-mentioned 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.

Effect By mixing iron ore and carbonaceous materials and charging them 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 less pressure loss. Therefore, it is not necessary to specifically coke the carbonaceous material, and it is possible to use a carbonaceous material with a volatile content of 5% or less without undergoing coking treatment. The use of unprocessed carbonaceous materials for coking is extremely complicated;
Eliminate environmentally undesirable tasks. 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 10 mm or less.

EXAMPLES 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 and coke of 5 mm or more in accordance with the above-mentioned conventional method. (sintered ore)
The results of detailed measurements of pressure loss in each temperature range in the furnace are as follows: 650 mm and 500 mm of coke are alternately charged from the top of the furnace and operated with hot air blowing from the tuyeres. As shown in Figure 1, up to 1200℃, the pressure loss is slight, not even reaching 50mmH ₂ O, but beyond this 1200℃, the pressure loss increases rapidly, and in the band around 1400℃. A peak point exceeding 400 mmH ₂ O is shown, and in the temperature range above that, the pressure loss decreases again, reaching several tens of mmH ₂ O at about 1600°C. Of course, the specific values and peak point position of the pressure drop mentioned above vary depending on the quality of the ore used, such as the reduction rate.For example, the peak point is about 1200 to 1420℃. It appears within the range of , and the pressure loss value at the peak point is also
Even if the temperature is within the range of 300 to 700 mmH ₂ O, the general situation will be as shown in FIG. 1. 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. In addition, the molten metal flowed down and penetrated into the coke layer, and it is recognized that this is due to the fact that the voids between the particles in the charged layer are clogged. In addition, when such void clogging occurs in a temperature range of 1500 DEG to 1600 DEG C., the metal component is separated from the coke layer by flowing down and the coke layer becomes almost exclusively present, thereby reducing the pressure loss 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 ore) and coke in equal volume ratios. 1st
The pressure loss was measured in each temperature range in the same manner as shown in the figure, and the results are shown in Figure 2.The pressure loss peak point around 1400℃ was easily and completely eliminated.
It was confirmed that the temperature was several tens of mmH ₂ O or less in the entire temperature range, and it was found that the ventilation condition became uniform and the furnace condition and other conditions became stable and good.

However, if the ventilation conditions in the furnace can be improved as described above, and the pressure loss (i.e. ventilation conditions) can be improved, especially in a high temperature zone such as 1200°C or higher, then a coking treated carbon material can be used as the carbon material. It is presumed that it is not necessarily a requirement to do so, and based on these technical relationships, details regarding the adoption of carbonaceous material that does not turn into coke according to the above-mentioned method of mixing and charging iron ore and carbonaceous material are being considered. After extensive study, the present invention was completed. In other words, if the carbonaceous material used for this purpose has a high volatile content, this volatile content will be evaporated from the raw material charged into the blast furnace, and this will cause problems in the blast furnace gas cleaning system that is common today. impede function. However, the results of examining the content of such volatile matter show that although it is related to the amount of the carbonaceous material blended, in general, if it is less than 5%, it is difficult to mix it with ores such as sintered ore and use it. It was confirmed that the amount of volatilization in the blast furnace gas is small, and that it can be implemented without impairing the functions of the electrostatic precipitator in the blast furnace gas purification 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 below.

Operation example 1 Hongay coal from Vietnam (VM = 4.2%) 8~
25 mm is used as carbon material, while iron ore is 8
Using blending ore of ~25 mm and sintered ore of 5 to 50 mm, a mixture of such carbonaceous material and iron ore with an ore/charcoal material ratio (O/C) of 2.20 was charged into a blast furnace and Operation was carried out by blowing hot air at 1100°C from the mouth at a pressure of 2.5 kg/cm ³ .

The pressure loss peak point in the hot air zone of 1300 to 1400°C in the furnace is 60 mmH ₂ O, allowing stable blast furnace operation, and the volatile content in the blast furnace gas recovery system was measured at 40 ppm. It was confirmed that there was no problem with the operation of electrostatic precipitators, etc. Further, even when the mixing ratio of Bongei coal and coke was 2:1 in bulk ratio, stable operation could be achieved with the volatile content of the blast furnace gas recovery system being 50 ppm.

Operation example 2 Samshindong coal from North Korea (VM = 2%) 8-25mm
8 to 25 as iron ore.
Using blended ore of mm and sintered ore of 25 to 75 mm, a mixture of such carbonaceous material and iron ore with an ore/carbonaceous ratio (O/C) of 2.20 was charged into a blast furnace, and the tuyere The reactor was operated by blowing hot air at 1100°C at a pressure of 2.5 kg/cm ³ .

The pressure loss peak point in the hot air zone of 1300 to 1400℃ inside the furnace is 60 mmH ₂ O, allowing stable blast furnace operation, and the volatile content in the blast furnace gas recovery system was measured at 35 ppm. As in Operation Example 1, there was no problem in the operation of the electrostatic precipitator, etc.

Operation example 3 The charcoal material is 8-25 mm of charcoal (VM = 0.2%), while the iron ore is blended ore of 8-25 mm and sintered ore of 25-75 mm. A mixture of iron ore and iron ore with an ore/charcoal ratio (O/C) of 2.10 was charged into a blast furnace, and 1100
It was operated by blowing hot air at a temperature of 2.2 kg/cm ³ at a pressure of 2.2 kg/cm 3 .

The pressure loss peak point in the hot air zone of 1300 to 1400°C in the furnace is 70 mmH ₂ O, allowing stable blast furnace operation, and the volatile content in the blast furnace gas recovery system was measured at 30 ppm. It was confirmed that there was no problem in the operation of the electrostatic precipitator, etc., as in the case of operation examples 1 and 2. In other words, in this case, although no coke was used at all, it was confirmed that a preferable blast furnace operation was possible. did.

"Effects of the Invention" According to the present invention as described above, by charging a mixture of carbonaceous material and ore, the ventilation properties of the softened and molten zone in the blast furnace are improved, and an advantageous effect with uniformity and low pressure loss is achieved. It enables blast furnace operation, does not particularly require coking as the above-mentioned carbonaceous material, and uses a carbonaceous material with a volatile content of 5% or less without undergoing coking treatment, making the coking process extremely complicated. 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 possible to operate a blast furnace at sufficiently low costs and with low energy consumption. It is clear that this invention is capable of realizing the following and has great industrial effects.

[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 zone in conventional blast furnace operation, and Figure 2 is a diagram showing the mixed charging of carbonaceous material and ore of the present invention. 2 is a chart showing the same relationship as in FIG. 1 for one example of FIG.

Claims (1)

[Claims] 1. 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 not subjected to coking treatment are mixed with the iron ore. A blast furnace operating method characterized by charging.