JPS6028882B2 - Blast furnace bottom lining structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lining structure for a blast furnace bottom, and more particularly to a lining structure for a blast furnace bottom that can prevent abnormal damage caused by erosion of hot metal at the bottom of a blast furnace.

Carbon bricks are usually used in the sump and bottom of blast furnaces.

The reason for this is that carbon bricks inherently have high corrosion resistance against hot metal and high thermal conductivity, so cooling the iron shell forms a solidified layer of molten iron on the brick surface inside the furnace, which has the effect of protecting the carbon bricks. It is. However, in recent years, blast furnaces have become larger and their operating conditions have become harsher.
Abnormal damage due to erosion of molten iron began to be seen in the area of the bottom of the furnace directly below the side wall of the sump, as shown by dotted line A in Figure 1.

Since such abnormal damage to the bottom of the furnace becomes a fatal defect that determines the life of the blast furnace, its prevention has become an extremely important issue. An object of the present invention is to provide an effective lining structure capable of preventing abnormal damage to the blast furnace bottom, including the blast furnace sump and the bottom made of carbon bricks.

The gist of the present invention is as follows.

That is, in the lining structure of the blast furnace hearth, the lining structure of the blast furnace hearth has a flaw side wall made of carbon bricks, a hearth bottom, and a furnace inside stamp that absorbs the expansion of the hearth bottom refractory material inside the blast furnace shell. Containing SIC at a cloud content of 3% or more in the operating surface side part of the lower side wall brick and in the furnace inner part of the brick that is located at the bottom of the furnace below the side wall of the flaw reservoir and is lined between the steel shell and the furnace inner stamp. This is a blast furnace bottom lining structure characterized by arranging SIC-C bricks. The present inventors investigated and researched the cause of the above-mentioned abnormal damage to the outer periphery immediately below the side wall of the flaw reservoir at the bottom of the blast furnace, and as a result, the following facts became clear.

That is, in a blast furnace, raw materials such as iron ore, morning concretion, coke, and limestone are charged from the upper part of the furnace, and these raw materials contain alkali and zinc oxide. As these components descend through the blast furnace, they are reduced by coke, become metal vapor, and ascend through the furnace. However, when they reach the low-temperature area at the top of the furnace shaft, they are oxidized again, becoming oxides, and descending through the furnace. do. It was discovered that the alkali and zinc vapors not only repeatedly rise and fall within the furnace, but also absorbed into the carbon bricks, which are the refractory lining at the bottom of the blast furnace, causing damage to the carbon bricks. In other words, the alkali and zinc vapors that entered the carbon brick through the pores at a certain temperature will cause the following '1',
(2) Reacts with CO gas in the furnace to generate metal oxides and carbon. Next(90C0(91K20(s)
) + CG)...{1}Zn turtle) 10 CO bee) → Zn○(
s)+CG)...(21) These collective precipitations generate fine cracks within the carbon brick.

When the temperature inside the furnace rises, the reverse reaction of formula '1' and (2) above occurs, and the precipitated metal oxide and carbon are gasified again, making the carbon brick in the deposited part porous.

This repetition of oxidation and reduction 1 forms a porous deoxidized layer within the carbon brick, which acts as a heat insulating layer and causes a rise in temperature inside the furnace, promoting carburization and dissolution of the carbon brick into hot metal. As a result, it became clear that the carbon bricks themselves gradually eroded, causing abnormal damage.
Next, the present inventors conducted comparative research on various materials for preventing damage to the carbon bricks, and as a result, it became clear that refractories containing SIC exhibit remarkable effects against alkali and zinc.

That is, as shown in the experimental example below, when a SIC-C refractory containing 3% by weight or more of SIC is treated in alkali or zinc vapor, the porosity and air permeability decrease and the strength increases; It has been found that when conventional carbon bricks are subjected to the same treatment, they become porous and their strength deteriorates, contrary to the case of SIC-C bricks. Experimental Example 1 A comparison test was conducted on the corrosion resistance against alkali between the SIC-C brick according to the present invention and a conventional carbon brick used for the peripheral part of the bottom of a blast furnace.

Using Kyo03, a typical alkali, SIC-C
2 enemies x 2 from each specimen of carbon brick and carbon brick
Cut out a test piece of 12 mounds, each with K2C03.
: Coke breeze = 1:1 weight ratio, total amount 2k
The mixture was placed in a SIC container together with the mixture of No. 9, heated and held at 90,000 for 3 hours in a siliconite electric furnace, and cooled in the furnace. The cooled test piece was placed in a SIC container with coke breeze and further heat treated at 1200 CO for 3 hours. This heat treatment was repeated five times, and the apparent porosity was measured for each treatment to determine the rate of change in the apparent porosity from the value before treatment.
The results are shown in Figure 2. In addition, the average K20 concentration of the cross section of the test piece after the 1st, 3rd, and 5th line return treatments was determined.

In Figure 2, "after one alkali" means 9 in a mixture of K2C03: coke breeze = 1:1.
It means that 00oo was heat-treated once for 3 hours,
"After one time of coke" means "after one time of alkali" and further heat-treated at 1200 qo for 3 hours in a coke breeze.

As is clear from FIG. 2, the rate of change in apparent porosity of the conventional carbon brick increases as the number of treatments during coke breeze increases, resulting in a curve similar to the C curve, whereas the SIC-C according to the present invention The rate of change in apparent porosity of the bricks decreases rapidly with alkali treatment, as shown by the S curve, indicating that the quality becomes extremely fine as the number of treatments increases. On the other hand, carbon bricks become porous due to the generation of cracks due to the intrusion of alkali.
Based on the above results, if SIC-C bricks are used for the bottom side wall of a blast furnace, even if oxides of alkali metals such as K20 are precipitated and reduced, the SIC-C bricks will become more and more densified and will not absorb alkali vapor. It is considered that no intrusion is allowed. Next, the above-mentioned 900 0 × pan r alkaline treatment and 12000
The amount of K20 in the cross section of the test piece after 1, 3, and 5 times of coke treatment for 0×3 hours was analyzed, and the amount of K20 infiltrated was measured. The results are shown in Table 1. Table 1 As is clear from Table 1, carbon bricks have an r of 90,000x.
After the first, third, and fifth alkali treatments, the amount of K20 infiltrated gradually increases, and the amount of K20 remaining after the coke treatment of 1200 oo x target r is also large.

This is N203, Si0, which exists as ash in bricks.
By the reaction between 2 and K20, K20・yama203×oi02
This is thought to be due to the formation of other composite compounds, and the increase in apparent porosity as shown in FIG. 2 suggests the occurrence of cracks due to the formation of such compounds. However, the SI of the present invention
For C-C bricks, alkali treatment of 90,000 x target r 5
The amount of K20 infiltrated even after the test was very small, less than 1% by weight.

Experimental Example 2 A comparison test was conducted on the corrosion resistance of SIC-C bricks according to the present invention and conventional carbon bricks against zinc. As in Experimental Example 1, test pieces of 2 kites x 20 legs x 12 kites were cut from each of the C-C brick and carbon brick specimens, each with a weight ratio of Zn:Coke please = 1:1. The mixture was placed in a SIC container together with a total amount of 2k9 mixture, and subjected to a 90,000x universal 0 heat treatment in a siliconite electric furnace and cooled in the furnace. The cooled test piece was further placed in a SIC container with coke breeze and subjected to 120,000x pan-r heat treatment. This heat treatment was repeated five times, and the apparent porosity was measured for each treatment to determine the rate of change in the apparent porosity from the value before treatment. The results are shown in Figure 3. As is clear from Figure 3, in the case of SIC-C bricks, the apparent porosity tends to decrease and become denser with repeated treatments, whereas in the case of carbon bricks, the apparent porosity tends to decrease and become more densified with zinc treatment. Although the porosity decreases, it becomes larger than the apparent porosity of the original brick after coke treatment at 1200°C, and shows a tendency to increase as the number of coke treatments increases.

This is due to the progress of porosity due to the occurrence of cracks due to the precipitation of zinc oxide. As is clear from the above experimental examples, it has become clear that the SIC-C brick exhibits strong corrosion resistance against alkali and zinc, and can prevent abnormal damage to the bottom of the blast furnace.

However, in the present invention, the amount of SIC in the SIC-C brick is 3
% by weight or more. The reason is SIC
When the amount is 30% by weight, the apparent porosity increases due to the porosity caused by the oxidation and reduction reactions between the alkali or zinc vapor and carbon that has entered the brick, and the reaction between these metal vapors and SIC. This is because the effect of reducing porosity and air permeability is not recognized because the densification phenomenon caused by the decrease in porosity and air permeability is offset. As mentioned above, SIC is used as a countermeasure for abnormal damage at the bottom of a blast furnace.
By using SIC-C bricks containing 3% or more by weight, it is possible to completely prevent conventional carbon bricks from becoming porous due to the intrusion of alkali and zinc vapor, dramatically extending the life of the blast furnace. can do.

Next, an example of a lining structure for the bottom of a blast furnace using SIC-C bricks having a weight percent of SIC3 or more will be described.

Embodiment FIG. 4 is a schematic partial sectional view showing the lining structure of the bottom of a blast furnace according to the present invention.

As shown in FIG. 4, carbon bricks 6 are stacked on the inside of the shell 2 with a stamp material 4 on the shell side interposed therebetween to form the side wall 8 of the tundish part and the bottom part 10 of the furnace. The above-mentioned SIC-C bricks 12 are placed on the lowermost stage of the side wall 8 of the sump, or as shown in FIG. 8, one or more tiers of bricks including the uppermost tier of the furnace bottom 10 below the inner brick 14 shown in FIG.
The arrangement is as shown in FIG. 5, and the furnace bottom 10' is lined with carbon bricks 6 through a furnace inner stamp material 16 that absorbs the expansion of the furnace bottom refractory. Therefore, in this case, it is placed at the innermost side of the sump side wall 8 sandwiched between the carbon bricks 6 adjacent to the iron skin 2 at the bottom of the blast furnace, and at the outer periphery of the inside stamp 16 at the bottom of the furnace 10. As a result, abnormal damage as shown by the dotted line A that occurred when only the conventional carbon brick 6 was used can be prevented from becoming normal damage as shown by the one-dot iron line B, and further erosion can be avoided. Therefore, the life of the blast furnace can be significantly extended. The SIC-C bricks 12 containing 30% by weight or more of SIC may be arranged in a stepwise manner as shown in FIG.

That is, in this case, the SIC-C bricks 12 disposed on the movable surface side of the side wall 8 of the damaged reservoir are arranged in two or more stages including the innermost or lowest stage, as in FIGS. 4 and 5, and The bricks lined between the steel skin 2 of the lower furnace bottom 10 and the furnace inner stamp 16 are arranged in a stair-like manner from the top to the inside of the furnace, and at the joint with the carbon brick 6 in the center. The structure is such that the furnace inside stamp 16 is filled. In this case, when only the subordinate carbon brick 6 was used, the abnormally damaged part as shown by the dotted line A is shown by the dashed line C.
It is possible to prevent normal bowl-shaped damage as shown in , and the life of the blast furnace can be significantly extended. The method of constructing SIC-C bricks for the lining structure of the bottom of a blast furnace according to the present invention has been described above, but since SIC-C bricks are expensive, it is difficult to use a method that maximizes the effect with the minimum amount of use. It goes without saying that various embodiments other than the above two embodiments are possible within the scope of the claims of the present invention.

In either embodiment, abnormal damage to the blast furnace bottom can be effectively prevented by arranging SIC-C bricks containing 3% by weight or more of SIC in the limited area of the blast furnace bottom according to the present invention. . The length of the SIC-C bricks is preferably 1/4 to 1/4 of the total length of each of the lower bricks on the side walls of the sump and the lining bricks on the furnace bottom below the side walls of the sump, as shown in Figures 4 to 6. It is desirable that it be 1/2. In addition, when using and arranging SIC-C bricks, there are two methods: bonding them with conventional carbon materials using brick adhesive, or using bricks made with SIC-C bricks as one piece when manufacturing carbon bricks as a lining. Good too.
As is clear from the above-mentioned invention and examples, the present invention has the advantage that the lining structure of the blast furnace hearth, which is mainly made of carbon bricks, uses only carbon bricks or Chamott bricks only in the center of the hearth bottom. Zinc makes it porous and erodes into the molten iron, causing abnormal damage to the bottom of the furnace and becoming a serious defect that affects the life of the blast furnace.
SIC- containing more than 3% by weight of SIC3, which does not become porous to alkali and zinc, but rather causes densification.
By discovering the characteristics of C-type bricks and using them for the bottom of blast furnaces, we were able to achieve the following effects.

'i} According to the present invention, SI containing at least low weight % of SIC3
C-C bricks are placed in limited areas at the bottom of the blast furnace, that is, on the working surface side of the bricks at the bottom of the side wall of the sump and at the bottom of the furnace below the side wall of the sump, between the iron shell and the furnace inside stamp. By placing it inside the furnace of the lining bricks,
This prevents the conventional abnormal damage caused by alkali and zinc to the bottom of the furnace, making it possible to significantly extend the life of the blast furnace.

[o} The purpose of the SIC-C bricks used in the present invention is to achieve the maximum effect with the minimum amount of use, so if the extension of the life of the blast furnace is considered, the increase in the construction cost of the blast furnace can be compensated for. I have some left over.

[Brief explanation of the drawing]

Figure 1 shows the side wall and bottom of the sump of a conventional blast furnace constructed only of carbon bricks, and the abnormal damage line A on the bottom of the furnace.
Figure 2 is a vague partial cross-sectional view of the bottom of the blast furnace showing SIC-C.
A diagram comparing the effects of alkali treatment and coke breeze treatment on the change rate of apparent porosity between SIC-C type bricks and carbon bricks, and Figure 3 shows the effect of zinc treatment and coke breeze treatment on SIC-C type bricks and carbon bricks. A diagram comparing the influence of the number of treatments on the rate of change in anchor porosity, and Figures 4 to 6 are schematic partial cross-sections showing examples of the lining structure of the bottom of a blast furnace using SIC-C bricks. It is a diagram. 2... Blast furnace shell, 4... Steel shell side stamp, 6...
Carbon brick, 8... Side wall of the sump, 10... Furnace bottom, 12... SIC-C brick, 14... Brick inside the side wall of the flawed sump, 16... Furnace inside stamp material. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. In a blast furnace bottom lining structure comprising a sump side wall made of carbon bricks on the inside of a blast furnace shell, a furnace bottom and a furnace inner stamp that absorbs expansion of the bottom refractory material, the side wall of the sump Si is applied to the movable surface side portion of the lower brick and the furnace inner portion of the brick that is lined between the steel shell and the furnace inner stamp at the bottom of the furnace below the side wall of the sump.
A lining structure for a blast furnace bottom, characterized in that SiC-C bricks containing 30% by weight or more of C are arranged.