JP2000007447A - Basic monolithic refractory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sinter a stamp material or mortar to high strength in a medium temp. range and to stabilize a refractory lining by specifying a compsn. consisting of a metal powder of a specified particle diameter contg. a specified amt. of Fe and MgO and further incorporating a specified amt. of a refractory material or a binder. SOLUTION: Basic monolithic refractories consisting of 0.2-10 wt.% metal powder of <=500 μm particle diameter contg. 30-100 wt.% Fe and the balance MgO or as needed, further contg. <=30 wt.% refractory material and/or, <=10 wt.% binder are used as a stamp material or mortar. The metal powder is preferably powder of steel other than stainless steel and high Cr steel contg. about >=8% Cr, pig iron or a ferroalloy. The refractory material is, e.g. silica, chamotte or alumina and the binder is, e.g. water, water glass, cement or gum arabic. The Fe in the metal powder is converted into a sintering aid by oxidation, sinters the MgO at a relatively low temp., exhibits high strength and keeps a lining sound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amorphous refractory used in a kiln for metal refining and the like.

[0002]

2. Description of the Related Art Stamp materials and mortars, which are irregular refractories, are widely used in various places. Stamp materials are widely used not only as a wear lining for kilns but also as fillers for expansion allowances due to filling gaps and their shrinkability. Construction can be done dry without adding moisture, or several weight percent
It is constructed by a wet method to which a binder such as water is added. As the binder, not only water but also bittern (aqueous solution containing magnesium chloride as a main component), water glass (aqueous sodium silicate solution), or a mortar binder described below may be used.

[0003] Mortar is mainly used for filling joints of fixed refractories such as bricks, but is also used for filling gaps and as a filler for expansion as well as stamp materials. As the binder of the mortar, the above-mentioned water, bittern and water glass, including inorganic glass, silicate, phosphate, sol, low melting point, cement, clay, organic-based gum arabic, dextrin,
Starch, water-soluble polymer compounds, resins and the like are used.

By the way, from the viewpoint of adding metal powder to refractories and their materials, the following known techniques exist. That is, Japanese Patent Application Laid-Open No. 2-141465 discloses an example of adding a chromium-containing metal powder to a basic refractory raw material, and Japanese Patent Application Laid-Open No. 55-109281 discloses an example of adding a metal aluminum powder to an alumina-based casting material. JP-A-54-394 discloses an example of adding a metal powder such as metallic aluminum to a magnesia-carbon refractory.
No. 22 publication. However, none of the metal powders is fundamentally different from the present invention in that the metal powder does not contain iron as an essential component, and the effects are also different.

On the other hand, a magnesia refractory to which stainless steel powder similar to iron powder is added is described in JP-A-6-107452. This is an invention related to a high corrosion-resistant basic refractory for the purpose of accelerating the precipitation of secondary spinel when a refractory is heat-treated. The effect is completely different from that of the invention.

[0006]

When an irregular refractory such as a stamp material or mortar is used as a filling material for a gap or an expansion allowance, if any gas flows into the gap or the expansion allowance, the stamp is caused by a gas flow. Lumber and mortar are carried away or moved and lost due to the tilting of the kiln, and gaps and expansion allowance become hollow, causing refractory linings to loosen and bricks to fall off. In addition, gas may be blown out from the joints of the wear brick through the cavity, and a hole may be formed. Further, when a carbon-containing refractory is used for the wear lining, if the amorphous refractory disappears and a cavity is formed, the carbon-containing refractory may be oxidized from the back side. Such a phenomenon is often observed when the space between the wear brick and the permanent brick in a vacuum chamber such as an RH facility is filled with an irregular refractory such as a stamp material or mortar. In this case, the main component of these amorphous refractories is magnesia (pericles).

[0007] The direct cause of disappearance of irregular refractories such as stamp materials and mortar is gas flow and tilting. However, these irregular refractories do not have sufficient strength and particles are apt to fall apart. There is. Taking as an example a filler between a wear brick and a permanent brick in a vacuum tank of an RH facility, a gap of 10 to 20 mm is often filled every time a brick is placed in one step. Fillers require fluidity, so in the case of stamp materials, dry or small amounts (5% by weight)
In the case of mortar, a binder is added as it is, or in the case of mortar, as it is, or a few weight% of clay is added and dry-filled, or water is added in an amount of about 10 to 20 weight% in many cases. By the way, the temperature near the boundary between the wear brick and the permanent brick depends on the remaining size of the wear brick.
000 ° C. This temperature range is also called an intermediate temperature range. Magnesia is difficult to sinter and does not sinter in this temperature range. Further, since the strength of the binder also decreases in this temperature range, these irregular refractories disappear due to gas flow or tilting.

An object of the present invention is to provide an amorphous refractory and mortar which are sintered in the above-mentioned intermediate temperature range of 500 to 1000 ° C. and have high strength.

[0009]

Means for Solving the Problems As a result of research and development for solving the problems, the present invention has been completed. That is, the gist of the present invention is that Fe is used as a chemical component.
, A basic amorphous refractory comprising 0.2 to 10% by weight of a metal powder having a particle size of 500 μm or less containing 30 to 100% by weight, and the balance consisting of magnesia, and further 30% by weight or less And a basic amorphous refractory containing one or two kinds of binders of 10% by weight or less.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The stamp material of the present invention and the irregular-shaped refractory such as mortar are mainly made of magnesia. The operation when filling the space between the wear brick and the permanent brick in the vacuum chamber will be described below.

[0011] Metal powder containing an iron component (hereinafter abbreviated as metal powder) is oxidized into oxide when the temperature of the entire refractory lining rises by drying, preheating and using the tank after construction. . Since the oxide acts as a sintering aid, magnesia sinters at a relatively low temperature and develops strength. For this reason, the refractory lining is kept healthy without being lost by the gas flow or tilting, and the carbon-containing refractory is not oxidized from the back side.

The above description has been made with reference to the example of filling the voids between the wear brick and the permanent brick. In addition to this, the stamp material can be used for wear lining and backup lining, and mortar can also be used as a joint material for brick construction. .

The magnesia used for the stamp material or the mortar of the present invention may be either an electrofused product or a sintered product. In addition, both natural products and synthetic products can be used. However, the purity is desirably 90% by weight or more from the viewpoint of corrosion resistance and strength.

As the metal powder containing an iron component, except for metals containing 8% or more of Cr such as stainless steel and ferrochrome, besides ordinary iron including steel and pig iron, ferrosilicon, ferromolybdenum, ferrovanadium, Ferroalloys such as ferroniob and ferroboron can also be used. C
Since metals containing r are hardly oxidized and hardly work as sintering aids, metals containing 8% or more of Cr such as stainless steel and ferrochrome are excluded from the metal powder of the present invention. Since elements other than iron in the ferroalloy may react with magnesia when oxidized depending on the type and cause a problem such as lowering the melting point, attention must be paid to the amount and composition of the ferroalloy. The Fe component in the metal powder is 3
0 to 100% by weight. This is because if it is less than 30% by weight, the effect of promoting sintering and the strength cannot be sufficiently obtained. F
It is more preferable that the content of the component e be 92% or more, since sufficient strength can be obtained.

The particle size of the metal powder is 500 μm or less.
This is to ensure appropriate reactivity. The amount of addition is set to 0.2 to 10% by weight. 0.2% by weight
If the amount is less than 10% by weight, the effect is not obtained. If the amount is more than 10% by weight, expansion due to oxidation and shrinkage due to sintering are increased, and volume stability is reduced, so that structural stability of the refractory lining is impaired. In addition, the greatest effect is from 0.3 to
4% by weight.

[0016] Refractory materials other than magnesia can also be blended. For example, silica, clay, chamotte, zircon, zirconia, mullite, alumina, chromia, spinel, chromite, calcia, dolomite, carbon, graphite,
Carbides, nitrides, borides and the like. It is necessary to adjust the addition amount within a range that does not impair the characteristics of the refractory, and it is at most 30% by weight, preferably 20% by weight or less.

The binder may be contained in an amount of 10% by weight or less, preferably 5% by weight or less. If the content is more than 10% by weight, many pores remain after the volatile components in the binder are volatilized, and the strength is reduced.

The amorphous refractory of the present invention can be used in a dry state or in a wet state with the addition of a binder. Since the metal powder easily reacts with moisture in the atmosphere, it is desirable to store the metal powder in a moisture-proof container if possible. Further, since the metal powder may react with the binder in some cases, the metal powder is used immediately after the addition. As a method for preventing hydration of the metal powder, a coating method with a resin as described in JP-A-3-170376 can be used.

[0019]

[Example 1] A mortar according to the present invention was applied to a gap of 15 mm between a permanent brick and a wear brick on a lower tank side wall of 300 tRH. In addition, the material of the brick was permanent magnet and the material was a magcro direct bond.
Synthetic sintered magnesia with a purity of 97% by weight or more 95% by weight
And 3% by weight of clay powder and 2% by weight of iron powder having a purity of 90% by weight or more and a particle size of 50 μm or less, to produce a mortar.

First, after the perm brick was constructed, the mortar was inserted into the gap between the back brick and the perm brick with an iron bar and dry-constructed each time the wear brick was constructed. Thereafter, the lower tank was used as usual, and after using about 550 ch, the condition of the refractory lining and the stamp material was investigated. The remaining size of the wear brick was 100 to 60 mm, and there was no noticeable loosening or abnormality. In addition, the mortar was sintered, and no disappeared portion was observed. The compressive strength of the remaining sintered mortar was measured and found to be 5 MPa. The mortar without the addition of ordinary iron powder was also dry-processed in the same manner, but the mortar disappeared in a groove shape in some places, and gas was blown out from the wear brick joint to form holes in some places. An attempt was made to measure the compressive strength of the mortar sintered body without the addition of iron powder, but the strength was insufficient and a sample could not be prepared, and measurement was impossible.

[Embodiment 2] As in the case of Embodiment 1, 3
The stamp material according to the present invention was applied to a gap of 15 mm between the permanent brick and the wear brick on the side wall of the lower tank at 00 tRH. This time, the wear brick was made of MgO-C. Purity 9
A stamp material was manufactured by adding 1% by weight of iron powder having a particle size of 150 μm or less to 99% by weight of synthetic sintered magnesia of 7% by weight or more.

The working method was the same as that of Example 1 except that the stamp material was kneaded after adding 3% by weight of water as a binder and kneading. Thereafter, the lower tank was used as usual, and after using about 500 ch, the condition of the refractory lining and the stamp material was investigated. The remaining size of the wear brick was 100 to 70 mm, and there was no noticeable loosening or abnormality. In addition, the stamp material was sintered, and no disappeared portion was observed. The back of the MgO-C brick was almost oxidized.

The stamp material was added with 3% by weight of water, stamped into a 40 × 40 × 40 mm mold, air-dried at room temperature for 24 hours after demolding, and dried in an air atmosphere for 100 hours.
Compressive strength measured at room temperature after heat treatment at 0 ° C for 3 hours is 6MPa, and 1MPa of that of iron powder-free product which was similarly constructed
Greatly exceeded.

[0024]

According to the irregular refractory of the present invention, the refractory lining of the kiln can be structurally stabilized, the operation of the kiln can be stabilized, and the life can be prolonged. As a result, it is possible to ultimately reduce the cost of manufacturing steel and the like.

Claims (2)

[Claims] 1. A metal powder having a particle size of 500 μm or less containing 30 to 100% by weight of Fe as a chemical component is 0.2 to 1%.
A basic amorphous refractory containing 0% by weight, with the balance consisting of magnesia. 2. The composition according to claim 1, further comprising not more than 30% by weight of refractory material and binder
2. The basic amorphous refractory according to claim 1, wherein the basic amorphous refractory contains 0% by weight or less of one or two types.