Mechanical activation of solids in processing of minerals and wastes

Recently, there has been an increasing interest in mechanical/mechanochemical activation of solids for developing new materials and metallurgical processes. In this paper, a brief overview of our research in this area is presented. Select applications of mechanical activation are discussed with emphasis on characterisation of activated materials, and the prospects and possibilities of developing improved/novel processes. The main applications covered include the Bayer process of alumina production, and blended cement manufacturing

Geopolymers, fly ash reactivity and mechanical activation

The foucs this paper is on the reactivity of fly ash in relation to its geopolymerisation, that is structure and properies of geopolymer. A comparision of the mechanically induced reactivity by vibration and attrition milling and glass content induced reactivity obtained through size classification in a high speed air classifier has been made. It has been shown that for the fly ash of nearly same size (~ 5 µm), mechanical activation results in higher reactivity or geopoymerisation rate as compared to the air classified samples. Reactvity can also be altered by mixing raw fly ash with processed fly ash. Much wider variation in the reactivity is possible by mixing raw fly ash with mechanically activated fly ash than with classified fly ash. Higher reactivity of the mechanically activated fly ash results higher strength vis-à-vis raw and air classified fly ash