Chinese research into utilisation of coal waste in ceramics, refractories and cements

Abstract

Disposal of coal mine waste (gangue) presents a serious environmental problem. In the present paper, applications of siliceous and kaolinitic gangues in ceramics, refractories and cementing materials are reviewed. Coal gangue series mullite, superfine β-SiC and Si₃N₄ powder have been prepared from siliceous gangue and carbon black, anthracite or bituminous coal. Using kaolinitic gangue with few impurities as raw materials, Al₂O₃–SiC and sialon–SiC composite powders, and sialon series powders including β-sialon, O-sialon and X phase have also been synthesised successfully. Kaolinitic gangue has been used to produce porous ceramics, cordierite, cordierite–mullite insulating brick, anorthite lightweight brick and other lightweight aggregates. Calcined coal gangue had high activity of volcanic ash and may be used as a cement admixture. Alkali activation is another effective method of improving the strength of coal gangue based alkaline cementitious materials.

Keywords:

• CEMENTS
• CERAMICS
• COAL WASTE
• MULLITE
• REFRACTORIES