JPS62108764A - Refractories for molten metal vessel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to refractories used in the steel industry and the like.

[Prior Art] Pure oxygen converter operation brought about a major change from secondary to bottom blowing to top and bottom blowing, and the advent of magnesia carbon bricks greatly supported this change. Magnesia, which was developed mainly for electric furnaces in the 1960s,
Carbon bricks were fired products that were bonded with tar and subjected to reduction firing, but in the late 1940s, unfired magnesia carbon bricks were developed by using thermosetting resin as a binding material for refractories, and in the 50s. The first half was a time when fired dolomite bricks, which had been the mainstream until then, were rapidly replaced by unfired magnesia carbon bricks, which had more than twice the corrosion resistance. In the late 1950s, efforts were made to improve the performance of magnesia carbon bricks, and magnesia carbon bricks
High purity of clinker, coarse crystallization, high purity of graphite,
Performance has improved considerably through various improvements such as the use of electrofused magnesia, high density using a large vacuum press, and the addition of gold for oxidation prevention. On the other hand, converter operation is also mainstream.
The magnesia carbon brick lining, which was fixed by double-bottom blowing, has poor adhesion of repair materials compared to the former fired dolomite bricks, making it difficult to prevent local erosion, and the balance of wear and tear can be improved by changing the performance of the material and the lining ring. I was forced to take it. In particular, wear and tear is diversifying, such as wear and tear on the bottom section where the bottom blowing nozzle is located and the steel bath section, and wear and tear on the furnace due to energy auxiliary operations, and the demand for high-performance furnace materials that maintain balance at increasingly high levels is increasing. It's here. Even when magnesia carbon bricks, which use large amounts of expensive electrofused magnesia, are placed in the most difficult areas, they are at their best, and areas with little wear and tear are discarded with large residual thicknesses, resulting in waste.

Conventional magnesia-carbon bricks have almost reached their final stage, and in order to meet the ever-increasing demand for high-performance furnace materials that take economic efficiency into account, new fire-resistant materials that break through this magnesia-carbon barrier are needed. Development of material technology is strongly desired.

[Problems to be solved by the invention] The present invention was obtained as a result of research into the functions of magnesia and carbon that constitute magnesia-carbon bricks. Focusing on the slag coating effect of the aggregate and the reaction layer protection effect, we have developed a new method by controlling the shape, size, distribution density, and directionality of the coarse particles of the aggregate, in order to maximize the effects of the aggregate. The aim is to create refractories with innovative performance and to provide refractories with revolutionary performance as linings for molten metal containers.

[Means for solving the problems] The present invention provides one or more types of carbon raw materials such as graphite, coke, and oil carbon, and/or one or more types of high carbon residual resins such as resin, pitch, and tar. A molten metal characterized in that the corrosion-resistant aggregate as the main component has a long columnar shape, and the long columnar aggregates are arranged in a direction perpendicular to the heat-eroded surface. It is a refractory material for containers.

[Function] The present invention will be explained in detail below. First, conventional magnesia carbon bricks will be explained.

The advantages of magnesia carbon bricks derive from the graphite used therein and the carbon bond. Graphite's high thermal conductivity not only lowers the temperature of the working surface and significantly reduces the speed of erosion reactions, but graphite's resistance to wetting limits the infiltration of foreign slag to a very thin surface layer on the working surface. . Therefore, the corrosion of bricks is mainly caused by gas phase oxidation due to oxygen partial pressure, liquid phase oxidation of slag, etc., and internal 5in2. Fe.

Oxidation etc. due to the catalytic action of impurities such as 01 etc. 1-
And the oxidation of carbon at the bonding part is rate-determining. Next, we will discuss the use of conventional magnesia carbon bricks.

The aggregate particles of magnesia carbon bricks are characterized by their chemical composition and crystal structure, S ioz tA ] 2
By reducing impurities such as 03 HF e 203 HB 203, the wear speed of bricks is reduced both in the laboratory and in actual furnaces, and the corrosion resistance performance is improved.

As a result of collecting and observing many used astringent bricks, we found that coarse aggregate particles, which are considered important in this way, protrude from the carbon-containing fine particle part (hereinafter referred to as the matrix part) in most cases, and in some cases large particles that have fallen off. Holes can also be seen. High-purity electrofused magnesia has protrusions while maintaining its original particle shape, while calcined magnesia clinker has slightly rounded corners and protrusions, and in general, high-purity products have a larger protrusion.

Therefore, the coarse aggregate particles of magnesia carbon bricks play the role of a bulwark against flow erosion that washes over the working surface, promoting slab coating, and retaining a viscous reaction layer. This has the effect of reducing the erosion effect on the parts. In fact, in actual furnace tests, the wear speed of the bricks using magnesia clinker with a top size of 5 mm and the bricks using magnesia clinker with a top size of 1n+m was 30% lower.

Figure 3 shows a cross-sectional view of a conventional magnesia-carbon brick used in a top-bottom blowing converter. 1 is the protruding magnesia particles, 2 is the coated slag layer, and 3 is the area after the fallen magnesia particles have fallen off. 4 is the raw brick composition. Erosion of the matrix is progressing.

When the part of the roots that have bitten into the raw bricks of the coarse aggregate decreases, it suddenly falls off as shown in 3, and after that, the slab attacks, so it erodes at a fairly high speed until the next coarse aggregate is cursed. progresses.

Through numerous photographic observations by the present inventors, it has been found that this shedding occurs at the roots of 30 to 40% of the coarse aggregate, and that only the protruding surface of the coarse aggregate becomes an erosion resistor to the point where it becomes slightly rounded. However, it then falls off and the instantaneous erosion speed increases in some areas. Since the operating surface is made up of a collection of such parts, it is important to prevent them from falling off.

Next, the present invention will be explained in detail. The present invention utilizes one or more carbon raw materials such as graphite, coke, and oil carbon, and/or one or more high carbon residual resins such as resin, pitch, and tar.
It is a carbon-containing refractory containing one or more species. The reason for using a carbon-containing refractory here is that carbon's strength against wetting can prevent infiltration of the slab. Similar wetting resistance can be expected with 13N (hexagonal crystal). In some cases, we can also expect SiC and 84G. In a matrix configuration in which infiltration cannot be prevented, the feature of using the long columnar coarse aggregate of the present invention disappears, and the infiltrated layers structurally spall or peel one after another. The present inventors have claimed carbon as a typical inexpensive material that is resistant to wetness, but if BN becomes economically viable as a raw material for refractories, then of course it can also be used.

The present invention is also a refractory characterized in that the corrosion-resistant aggregate, which is a weight component, is in the form of long columns, and the long column-shaped aggregates are arranged in a direction perpendicular to the brick operating surface. Aggregate components are magnesia or zirconia for converters, alumina, magnesia/dolomite, mag/
It can be used as long as it is resistant to erosion, such as a fluorocarbon type. Clinkers are emerging that can also be used for magnesia-lime systems in converters. Zirconia is also suitable for the converter outlet and tuyeres. In the future, non-oxide materials such as SiC, Si, and N4 aggregates can be used in blast furnaces. The key point is that the corrosion-resistant aggregate made of these components is more resistant to erosion than the matrix portion, and these protruding aggregates form a slag film to protect the matrix.

Next, the shape and dimensions of the aggregate will be explained.

FIG. 1 is an example of aggregate. 5 is a straight rod-shaped object, for example, a rod-like object with a diameter of 5 mm and a length of 30 mm is likely to fall off when the length decreases due to erosion and reaches 2 to 3 Ia11. 6 is provided with a threaded concave and convex portion, which does not easily fall off even in a reduced state.

No. 7 has large four parts, which is also effective against falling off. 8, 8A has a round cross section and 8A has an uneven portion; 9, 9A has a square cross section and 9A has an uneven portion; 10. The IOA has a hexagonal cross section, and the IOA also has an uneven portion.The uneven portion is effective against falling off. However, on the other hand, it is prone to breakage during the manufacturing of the tarinkar and during brick molding, so it has both advantages and disadvantages.

Long columnar coarse aggregates are divided into type A with a cross-sectional diameter of 3 to 5 mm, type B with a cross-sectional diameter of 1 to 3 mm, and type C with a cross-sectional diameter of 0.3 to 1 mm. It is convenient and does not require much particle size packing.

However, the length is preferably 3 times or more and less than 15 times the diameter.

If the length is too long, folding during manufacturing and spalling during use are likely to occur, which is undesirable.

Figure 2 shows A-type aggregate with a diameter of 4 Inffl and a length of 30 mm. It is a cross-sectional view and a side view arranged in one grid. In this case, the aggregate occupies about 50% of the volume, and the rest is the carbon-containing matrix. If the aggregate has the same cross-sectional structure and a diameter of 5 mm without changing the distance between the sections, the volume of the aggregate can be increased to 76%. Furthermore, if the size is 4.5 mm square, the volume of aggregate can be up to 78.4%. In this case, the gap is 1 mm in each case, and the matrix portion is located there. If this is further made into a regular hexagonal aggregate with sides of 2.6 mm, the volume of the aggregate can be increased to 93%. In the case of this hexagon, a gap of 1 mm is left between each side of the hexagon. In short, by selecting the shape, it is possible to adjust the volume ratio of coarse aggregate in any way without impairing the presence of the matrix.

Different aggregates may be used depending on the size, thickness, and shape of the bricks, but in the case of the molten metal containers made by the present inventors, type A and type B are often used.

The arrow in FIG. 2 indicates the working surface, and the base of the protruding coarse aggregate is the reaction layer due to slag adhesion. By increasing the volume ratio of coarse aggregate, the corrosion resistance of the matrix part becomes less of a problem, and rather the use of CaO and the amount of anti-oxidation metals are improved to suppress the reduction reaction of Mgo+c→M,, +C○. It is now possible to consider other aspects such as reduction.

Next, the method for manufacturing a refractory of the present invention will be described as an example.

[Example] Using an extrusion molding machine and a roll-type granulator used by a clinker manufacturer, the shapes of shapes 5 and 6 in FIG. A clinker with a diameter of 4 mm and a length of 30 mm was produced. The bulk specific gravity of the clinker is 3.45, and its composition is MgO: 98.5%, Sin: 0.3%
, Fe, O,: 0.5%.

B20. : 0.02%.

300kg of coarse aggregate clinker kept at 25℃ and particle size of 0.2mm with purity of 98% in the lower mixer for refractory manufacturing.
100 kg of scale graphite was added, 16 kg and 1 kg of commercially available high carbon residual resin and curing agent were added respectively, and the resin was sprinkled around the coarse aggregate and graphite. High purity magnesia clinker (MgO: 98.6%) was added and kneaded for about 40 minutes. The mixture was made to have coarse aggregate orientation in a mold by the method shown in FIG. In Fig. 4, 13 is the side wall and lower mold, 14 is the compound, 15 is a strong and flexible fabric, medium 20 mm, thickness Q, 6 + n + n, length is mold length minus 0, 5 ohm spring steel. 10+am+
A compound rolling belt is attached at intervals, 17 is a spring steel attached to the belt, and 16 is a section of fabric only between the spring steels. By pulling the belt long to one side or pulling it up alternately, the mixture was rearranged with shear, all along the length of the brick. When the rearrangement was completed, the belt was pulled out in one direction, leaving only the compound inside the mold.

1500kg/ by hydraulic pressurization method, 1501 by pressure of -d
A brick of X150+++n+X 450mm was molded.

The resin was cured at 200°C in a drying oven, and the general quality of the brick was measured. As a result, the bulk density was 3.10. The apparent porosity was 1.7%.

0 As a result of an erosion test of molten steel and slag using a high-frequency electric furnace, the wear of the highest grade magnesia carbon brick made of 60% high-purity electrofused magnesia is 47, assuming the wear is 100.
There was a lot of wear and tear.

These bricks were lined around the tapping port and at the intersection of the slag lines in a two-bottom blowing converter, where explosion losses are relatively high, and as a result of testing, it was found that magnesia and high-purity electrofused magnesia from the surrounding area could be used up to 500 taps. It was found that it protruded more than 100 mm than carbon bricks, and was extremely superior.

[Effects of the Invention] As described above, the present invention is significantly different from conventional refractory manufacturing technology in that it controls the shape, size, and arrangement of coarse aggregate, and is also superior in performance. This has a revolutionary effect.

In other words, the refractory according to the present invention exhibits 1.5 to 2 times more corrosion resistance than conventional products in the dynamic abrasion of steelmaking furnaces such as converters and electric furnaces, and has revolutionary performance. Mukai-no-Ki was recognized. That is, the product of the present invention promotes slag adhesion, delays liquid phase oxidation by slag in order to prevent slab refreshing, and is significantly improved in that it prevents gas phase oxidation. In the future, AOD, VOD, LF pot, DH
.

It is expected to have remarkable effects in many places where it is used, such as RH, steelmaking ladles, blast furnace linings, tap troughs, tap troughs, etc.

[Brief explanation of drawings]

Figure 1 shows an example of the shape of long columnar aggregate. Figure 2 shows the long columnar aggregate and matrix. Figure 3 is a cross-sectional view of a conventional brick after use. Figure 4 shows the refractory structure of the present invention. It is a figure which illustrated the manufacturing method.

Claims (1)

[Claims] In carbon-containing refractories containing one or more types of carbon raw materials such as graphite, coke, and oil carbon, and/or one or more types of high carbon residual resins such as resin, pitch, and tar, the main component is A refractory for a molten metal container, characterized in that the corrosion-resistant aggregate has a long columnar shape, and the long columnar aggregates are arranged in a direction perpendicular to a heating erosion surface.