JPS6236074A - Highly anticorrosive monolithic refractories - 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 highly corrosion-resistant monolithic refractories used as linings of ladles and the like that accommodate molten metal produced in melting furnaces such as converters and electric furnaces. .

Conventional technology In recent years, with the advancement of technology, user quality requirements for metals, especially mass-produced steel, have become stricter. began to be processed in some form by vacuum smelting or an alternative ex-furnace smelting process. In particular, the ladle refining method is widely adopted as a treatment for upgrading steel. These ladle refining methods are characterized by heating and stirring all the materials in the ladle, and therefore the refractories used in these ladle are subject to severe erosion by slag at high temperatures. Figure 4 shows an example of a ladle for refining in a sintered pot. The part of the refractory lining of such a ladle that is most severely eroded is the slag line, which is the part of the side wall that comes into contact with the slag.
Conventionally, the slag life part (^), which is the so-called peripheral part (B) formed at the boundary between the pot bottom and the side wall, is made of zircon bricks, zirconia bricks, or magnesia bricks.
Carbon bricks, etc. were used in the surrounding area (B), and ramming material and pouring material of 9-rucon were used.

Purpose of the invention However, zirconia bricks and magnesia-carbon bricks are extremely expensive, and zirconite (ZrO1/SiO
x) Bricks and monolithic refractories decompose into melting point i (Zr0t at 2570°C, !: 510m at 1700°C) at temperatures above 1500°C, so there is a problem that corrosion resistance significantly decreases above 1500°C. The object of the present invention is to eliminate such drawbacks and provide a relatively inexpensive refractory whose corrosion resistance does not deteriorate even at temperatures above 1500°C.

Structure of the Invention The present invention has been made with the above-mentioned object, and is directed to a bubble having an average particle size of 10 μm or less.
The gist of the invention is a highly corrosion-resistant refractory made by blending zircon in an amount of tnt% or less and the balance being zircon, and adding a binder. Baddeleyte is natural free zirconia and Zr0t.
Zircon is a substance that has the chemical formula ZrOx・SiOt, and its natural crystals are in the tetragonal system. When sintered with the compounded materials,
It refers to something that forms a matrix together with m th elements of the substance to be blended, and binds aggregate, which is coarse particles of the substance to be blended. Clay, bentonite, etc. are usually used as the binder.

As a result of various studies, the inventors of the present invention have made fine grains of Bubbly (Zrot) with a high melting point of 2570°C with an average particle size of 10 μm or less, and blended a small amount of the fine grains of Baddellite into zircon (ZrO, 5ift). This led to the knowledge that during firing, an extremely dense matrix is formed between the zircon (Z r Ox S i Ot ) aggregates together with a binder such as clay, and as a result, a refractory with extremely high corrosion resistance can be obtained. Obtained. The present invention is based on this knowledge.

The average particle size of baddeleyite blended in the present invention is 10
The reason for setting the value to be less than 1 μm is because even if baburites with an average particle size of more than 10 μm are blended, the effect of improving corrosion resistance is small (and corrosion resistance is improved significantly when bubblytes with an average particle size of 10 μm or less are blended). In addition, the reason why the amount of baddeleyte is set to 2% by weight or more and 8% by weight or less is because when the amount of baddellite is less than 2% by weight, corrosion resistance improves as the amount of baddellite increases, but when the amount is 2% by weight, the corrosion resistance improves. This is because the improvement in corrosion resistance begins to be saturated at 8% by weight, and the improvement in corrosion resistance is completely saturated at a blending amount of 8% by weight.

Implementation example 1 The present invention will be explained in detail by examples.

Zircon, which has the chemical composition shown in Table 1, is mixed with baddeleyte, which has the chemical composition shown in Table 2, which has been ground to an average particle size of 3 μm, in various proportions, and clay is added as a binder, and the outer arc length is 7.
It was sintered into a fan-shaped specimen measuring 0 l x width 75 mm x height 60 dragons, and was subjected to a rotational erosion test. FIG. 3 is a schematic diagram of a rotary erosion test device, in which (A) is a cross-sectional view thereof, and (B) is a cross-sectional view taken along the line AA in (A). Drum (1
) is slightly inclined with the right side of the figure (a) at the bottom, and most of the inner surface is lined with refractory bricks (2). A part of the drum (1) is lined with the fan-shaped test specimen (3), and an LPG/air/oxygen mixed gas burner (not shown) is inserted from the right side of the figure (A) to complete the drum. ) was heated to 1700°C, and molten steel and converter slag were introduced from the left side of the figure (a), and these were placed inside the drum (1). ), and at the same time the drum (1) was rotated by a rotating device (not shown) at a rate of 10 degrees per minute. After continuing the above-mentioned incubation state for 2 hours, the test specimens lined in the drum (1) were taken out, the central part of each test specimen was cut, and the area loss was measured. If the amount of baddeleyte blended was zero. area reduction of 1
Corrosion resistance index indicating the area loss for each baddeleyte content was calculated as 00.

Table 1: Zircon blended with test specimens Table 2: Baddeleyite blended with test specimens Figure 1 was obtained based on the results of the above test, with the horizontal axis representing the amount of baddellite in weight percent, and the vertical axis representing the corrosion resistance index. show. Fig. 1 shows that when the amount of baddeleyte is less than 1%, the corrosion resistance improves as the amount of baddeleyte increases, but at the amount of 2% by weight, the improvement in corrosion resistance begins to be saturated, and at the amount of 8% by weight, the corrosion resistance decreases. It can be seen that the improvement is completely saturated.

Example 2 The same test specimen as in Example 1 was prepared by adding 2% by weight of zircon, which has the chemical composition shown in Table 1, and 2% by weight of crushed baddellite, which has the chemical composition shown in Table 2, to give various average particle sizes. The same test as in Example 1 was conducted.

Figure 2 was obtained based on the results of the test, and
The corrosion resistance index is shown on the vertical axis with the average particle diameter of baddeleyite blended on the horizontal axis. From FIG. 2, it can be seen that when the average particle size of baddellite blended exceeds 10 μm, the effect of improving corrosion resistance is small, and when the average particle size is 10 μm or less, the corrosion resistance is significantly improved.

EXAMPLE Table 3 shows the results of the same tests as in Example 1 and Example 2 performed on zircon mixed with various weight percentages of baddellite having various average particle diameters. It can be seen from Table 3 that the monolithic refractories of the present invention have much better corrosion resistance than the comparative refractories.

Table 3 Effects of the Invention As mentioned above (the monolithic refractory of the present invention, which is made by blending a small amount of fine grained baddellite with zircon, has significantly better corrosion resistance than conventional refractories and is relatively inexpensive). Therefore, if used for the lining of a furnace that accommodates various molten metals, the life of the furnace will be extended, and it will greatly contribute to improving the production efficiency of various metals, reducing cost, etc.

The method for constructing the monolithic refractories of the present invention may be the pouring method or the spraying method, which may be used by any of the conventional enforcement methods for monolithic refractories, such as the Act. The same effect as above can be obtained.

[Brief explanation of the drawing]

Figure 1 is a diagram of the relationship between the amount of baddellite mixed and the corrosion resistance index, Figure 2 is a diagram of the relationship between the average grain size of baddeleyte and the corrosion resistance index,
Figure 3 is a schematic diagram of the rotary erosion test device, (a) is its cross-sectional view, (b) is a cross-sectional view taken along the arrow AA in (a), and Figure 4 is a schematic diagram of the rotary erosion testing device. It is a figure showing an example of a ladle. ! ... Drum 2 ... Refractory bricks 3 ... Test specimen A ... Slag line section B ... Surrounding section Toru 3 (B)

Claims (1)

[Claims] Baddeleyite with an average particle size of 10 μm or less 2% by weight or more 8
A highly corrosion-resistant monolithic refractory made by blending zircon with the balance of zircon at % by weight or less, and adding a binder.