KR880002431B1 - Refractory brick for used slag - Google Patents

Abstract

Refractory heat-insulating brick is manufactured by baking the refractory material at 1,150-1,300 deg.C. The refractory material consists of 88-96 wt.% of slag having a particle size of 1-2 mm and discharged from blast furnace, 2-6 wt.% of bentonite, 2-6 wt.% of refractory clay, and under 12wt.% of an aqueous solution comprising water and carboxymethyl-cellulose at the ratio of 50 to 50.

Description

Refractory insulating brick using blast furnace slag

1 is related to particle size and volume specific gravity of slag

2 is the specific gravity according to the firing temperature and additives

3 is compressive strength according to the firing temperature and additives

4 is compressive strength according to the addition of refractory clay and bentonite

5 is the specific gravity of the clay according to the amount of clay and bentonite added

The present invention relates to the production of internal and insulated bricks which can be used for increasing the thermal efficiency of various furnaces, mainly based on blast furnace slag produced by the steel industry.

Conventional methods for producing fire-resistant insulation brick include a method of expanding a natural raw material and then manufacturing it, adding a flammable or sublimable material into the raw material, and adding a foamable material. Methods are known and are classified by the nature of the raw materials used diatomaceous earth, pearl rock, obsidian, refractory clay, vermiculite.

In addition, in the method of using blast furnace slag, a method and apparatus for spheroidizing, lightening or expanding the slag are known, and the blast furnace slag is mixed with cement or water glass and dried at a temperature of 200 ° C. or lower. It is known to be able to utilize a high hardened body as a manufacturing and building member.

However, the known fireproof insulation brick manufacturing process requires pretreatment of raw materials and requires sublimation or flammable additives in the manufacturing process, which is a disadvantage in that the manufacturing process is complicated and the raw material price is high, particularly in the manufacture of hardened bodies using blast furnace slag. The publicly known technology is used only for construction at room temperature because it involves the risk of expansion and collapse when used at fireproof insulation temperature.

The reason is that the blast furnace slag is amorphous and has the characteristics that volume expansion occurs during the process of crystallization of the alumina component in the slag composition during the heat, so it is useful as an insulation or light weight aggregate but combines blast furnace slag only. There is a disadvantage in that the form can not be maintained when manufacturing the structure (構造 體) because it does not have its own cohesive force.

Therefore, the object of the present invention is to make a refractory insulation brick by adding slag as a main component and adding bentonite and refractory clay by using high-temperature expansion characteristics of wood slag to produce fire-retardant bricks to increase the utilization of slag which is a by-product in the steelmaking process and reheat shrinkage. The goal is to obtain this less fireproof insulating brick.

Hereinafter, the configuration of the present invention.

In order to improve the low temperature strength and the molding of the molded structure, a solution containing carboxymethyl cellulose, which is used as an organic binder, in water and a weight ratio of 50:50 was added at a weight ratio of 12% or less, and the organic binder was 300 ° C. At the above temperature, decay and loss of caking have been added, and bentonite and refractory clay, which are widely used as inorganic binders, were added to maintain the strength of the structure at a high temperature of more than 1200 ° C. Bentonite and refractory clay improve the strength of the structure in proportion to the amount added as shown in FIG. 4, but as shown in FIG. 5, the specific gravity of the structure increases due to the added volume. For the production, bentonite having a low volume specific gravity and refractory clay which improves the compressive strength while increasing the volume specific gravity were added by 4% by weight, respectively. In addition, as shown in FIG. 1, the volumetric load varies greatly depending on the particle size of the blast furnace slag, and after mixing the mixture with a slag having a particle size of 1 mm or more and 2 mm or less for 10 minutes and mixing in a mixer for 10 minutes The molded product was molded into a mold and dried at 110 ° C. for 2 hours, and then heated at a rate of 10 ° C. per minute and maintained at 1250 ° C. in an electric furnace for 2 hours. Conventional insulation refractory (clay or diatomaceous) shrinks at high temperature, so reheating shrinkage is a problem, but the fireproof insulation brick according to the present invention compensates for the problem of reheating shrinkage due to slight volume expansion at temperatures below 1250 ° C. Compared with refractory materials using expanded vermiculite, expanded pearlite expanded slag, and glass bubbles, pretreatment of raw materials can be omitted, which simplifies the manufacturing process, and uses waste as raw materials, which has advantages in cost reduction and waste utilization.

TABLE 1

Expansion Characteristics after Heating of 1-2 ㎜ Particle Slag

Experiments were conducted to determine the appropriate particle size of the slag, to determine the firing temperature of the specimen, and to determine the type and amount of the additives. As a result, 1-2 mm of the slag retreated in Fig. 1 and Table 1 was the lowest at 1250 ℃. Volume specific gravity is shown. As shown in FIG. 2 and FIG. 3, the bentonite, refractory clay, and alumina cement were added to the slag having a particle size of 1-2 mm each by 8% by weight, and then fired at an interval of 50 ° C. at 1150-1350 ° C. As a result, bentonite and refractory clay showed the lowest volume specific gravity and the highest compressive strength at 1250 ℃.

However, when fired at 1350 ° C., the aggregates softened.

Fireproof insulation brick should have low specific gravity, low thermal conductivity and high compressive strength. Blast furnace slag of the present invention has the property of expanding at high temperature, but because it does not have its own cohesion, it can not maintain a certain form alone, so the organic binder (carboxymethyl cellulose) was used to exert strength after drying and molding of the specimen The water content of less than 12% was added in relation to the efficiency of drying time.

In order to maintain the strength after high temperature firing, betonite and refractory clay, which can exhibit strength at about 1200 ° C, were added, and the optimum amount of the slag was determined by expanding slag of aggregate as shown in FIG. 2 through FIG. The additives were distributed at the interface and showed the bonding force, which was 8% or less in which the maximum compressive strength value, the lowest thermal conductivity and the bulk specific gravity could be obtained.

TABLE 2

Properties of Insulation Bricks Prepared after Mixing Additives in Slag

As described above, the present invention improves the reheat shrinkage problem of the pore-known clay fireproof insulation brick by manufacturing the B-5 grade fireproof insulation brick prescribed in KSL 3301 using blast furnace slag, and expands slag and vermiculite, pearlite obsidian, etc. Compared with the manufacture of used fireproof insulation bricks, the pretreatment of raw materials is omitted, which simplifies the process and increases the utilization and added value of the blast furnace slag, which is a by-product of the steel industry.

Claims (1)

Blast furnace slag with a particle diameter of 1-2 mm is 88-96% by weight, bentonite is 2-6% by weight and refractory clay is 2-6% by weight, and water and carboxymethyl cellulose are 50:50 aqueous solution. Fire-resistant insulating brick, characterized in that added to the raw material at a weight ratio of 12% or less, and fired at a temperature of 1,150 ℃ -1,300 ℃.

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