Abstract
When fused corundum is crushed, a finely dispersed powder is formed with an Al2O3 content of 93–95%, in the form of substandard material. It is advantageous to utilize this powder to obtain high-alumina chamotte with Al2O3 content of more than 62%. High-alumina aggregate (chamotte) was obtained by semi-dry technology with intermediate briquette molding from a mixture of corundum dispersed powder and enriched kaolin. Based on a final Al2O3 content of 65 wt. % the batch composition of the mass to produce a high alumina aggregate (chamotte) was calculated. From a mixture of dispersed corundum powder and kaolin moistened with a 5–7% technical lignosulfonate solution with a density of 1050 kg·m−3, a briquette was formed at a specific pressing pressure of 15–20 MPa. The briquette was fired at a temperature of 1700°C. The fired briquette had a strength of 164 to 193 MPa. The water absorption of briquettes was 11–12%. The phase composition of the briquette is represented mainly by corundum and mullite. The enriched kaolin did not show sintering effect on fine corundum.
Highlights
To produce mullite refractories with an Al2O3 content of 62–72%, the minerals of the sillimanite group are used: kyanite, andalusite, sillimanite, etc [1,2,3]
Minerals of the sillimanite group are mainly found in quartz rocks, in which other impurities containing alkali are simultaneously present
To produce a high-alumina aggregate using briquette technology, plastic molding was used with kaolin from the Kyshtymskoye deposit
Summary
To produce mullite refractories with an Al2O3 content of 62–72%, the minerals of the sillimanite group are used: kyanite (distin), andalusite, sillimanite, etc [1,2,3]. The total fluxes (CaO, MgO, Na2O, K2O, Fe2O3) should not exceed 3%, which is very difficult to achieve This is the main reason for the weak development of the production of high-alumina refractories from them, despite the significant reserves of this raw material. Deposits of kyanite that do not require enrichment are rare Another type of raw material to produce high alumina refractories is alumina hydrates: hydrargillite, boehmite, diasporas. These minerals are less likely than diasporas in the rock bauxite.
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