DE652909C - Process for the production of refractory compounds, in particular ramming compounds and mortars - Google Patents

Description

Process for the production of refractory masses, in particular ramming masses and mortar Sintered or molten basic or neutral refractory masses, such as sintered magnesia, sintered dolomite, magnesia chrome ore, etc., have a very low level Formability and a low strength of the molding in red heat. To increase this, it has been suggested to make supplements when deforming, which plastic or have binding properties or during the firing process by melting or chemical Reactions cause the individual particles to cement together. As such, surcharges are suggested: the basic mass of the refractory body itself in weakly fired States (caustic magnesia), oxides or hydroxides of metals (bauxite, aluminum hydroxide) or metalloids (silica, boric acid, zirconium hydroxide), alkalis, alkaline earths, also organic substances (tar, sulphite liquor).

Some additives have the purpose, through reactions in the structure to intervene the sintered refractory masses and thereby, in particular at appropriate grain size distribution, the sensitivity to temperature changes reduce (e.g. addition of ground bauxites or spinels to sintered magnesia, whose fine grain has been wholly or partially removed).

All these additions give the briquettes only a low mechanical level Strength; But they must not be added in larger quantities, otherwise they . have an unfavorable effect on the burning behavior and stability in the fire. Man also has refractory lean agents such as corundum, zircon - or the like, with additives provided, which consist of high-alumina cement. However, no refractory can be used here Products are obtained.

According to the invention, sintered or molten refractory masses with a content of at least 50 mol. Percent Mg O, calculated on the assumption that simple oxides are present in the refractory masses, are mixed with additives which, such as alumina cements (fused cements), are predominantly made Calcium oxide and aluminum oxide exist. Acid components, such as silica, may only be present to a minor extent, but the aluminum oxide can be partially replaced by iron oxide. High-alumina cements (fused cements) or related refractory cements or mortars are preferred as such substances.

So far, these have been used for stones and fodder that were not subjected to higher loads than corresponds to the melting of the high-alumina cement, ie at most 14oo ° C. Masses, which at SK. 13 / 1q. (138o to 1q.10 °) are not refractory because they are at least SK. 26 (-.- 158o °) have to withstand. Fireclay was used as the basic mass of these stones and fodder, which, regardless of whether it is called acidic or basic, is a 'silicic acid-containing raw material. -As a binder for the melted or sintered refractory materials with min? At least 50 mole percent Mg 0 is offered by the aggregates consisting predominantly of lime and alumina, such as alumina cements, which have the following advantages: If the correct amount of water is added (this must be determined for each type of material and for each grain size through preliminary tests), the molding receives such a large mechanical level Firmness that it can be shipped. The moldings have such a low heat shrinkage that they can be walled in without being burned.

The hand-shaping of entangled shaped stones is made much easier; these can be processed similarly to lean concrete blocks.

The values for the beginning of pressure softening (ta) and unstable pressure softening (te) will. due to the listed surcharges in most. Cases raised, and the stones or molding compounds obtained in this way also surprisingly hold in the In contrast to those with chamotte as the base material, with oven heat levels above r5oo ° C, well above the melting point of the high-alumina cement, considerable loads was standing.

The rapid hardening of the high-alumina cements also enables them to be manufactured Storage stable - sintered dolomite stones. The alumina cement quickly binds to deform necessary water and surrounds the individual grains, so that the moist air the lime in the sintered oil, so that water can no longer combine with it. Of course you can do this - only one. Use sinter dolomite, which during the setting time not yet drifting.

The most surprising advantage, however, is the significantly lower sensitivity against heat changes, especially if you consider the grain size composition in itself known to choose correctly. There are much more favorable values than for the proposed addition of similar bauxite, spinel, etc., as in contrast to Tile aggregates, calcium aluminate cement or similarly structured materials, almost the same Have expansion coefficients like the base material (e.g. Sinterznagnesia). This one The advantages described arise: of course, also during manufacture refractory ramming masses from: the melted or sintered materials.

: - If you increase the content of alumina cement, you get excellent, fireproof, more or less strongly alkaline mortar, which binds even with red heat. Compared to the usual Magnesitmörteln they have the advantage of higher softening and a greater adhesion.

Embodiments z. A sintered dolom with a grain size of o to z mm (which in a preliminary test even after four days of combined water and air storage no slaked lime is formed) with about 8% of calcium aluminate cement and about 8% of water mixed and pressed. The molding hardens after 24 hours and is after one Shipping within one week. Even after half a year it still shows up in moist air no rippling or drifting. It is bricked up in the unfired state.

2. Melted, very low-flux magnesia, grain size o to 5 mm, of which about half of the fine grain has been removed, is made with 81 /, high-alumina cement mixed; 'pressed with tar and fired in a gas-fired ring or tunnel kiln. The finished stones combine with an extraordinary fire resistance high resistance to heat change.

3. Mortar: Magnesite flour at 16 ° J, alumina cement mixed.

Claims (1)

PATENT CLAIM; Process for the production of refractory masses, in particular ramming and mortar, from magnesia-containing sintered or; molten starting materials and additives, - characterized in that sintered or molten refractory materials with a content of at least 50 mol percent Mg 0, such as. B. Sinterdolomit, used and additives are used, which, like alumina cements (fused cements), mainly consist of calcium oxide and aluminum oxide, while acidic components, such as silica, may only be present in the additives in small amounts and the aluminum oxide is partially replaced by iron oxide can.