Effects of calcination on mineralogical properties and reactivity of acidic aluminum sulfate residue

Abstract Acidic aluminum sulfate residue (AASR) is treated as a hazardous solid waste. However, it contains significant amounts of aluminosilicates which could be potentially utilized to produce geopolymers. The reactive activities of the aluminosilicate phases in AASR are generally low, which is a blockage of AASR-based activation to some extent. This paper aims to investigate the effect of calcination on mineralogical properties and reactivity of AASR at various temperatures ranging from 200 to 800°C. It was demonstrated that AASR underwent substantial changes in its mineralogical, chemical, and dissolution properties after calcination. The specific surface area, pore-volume, pH, dissolution efficiency of Si and Al were increased with increasing of calcination temperature until 600°C and then remained relatively stable at higher calcination temperatures. The results indicated that AASR is highly activated in a range of calcination temperatures between 600 and 800°C, which verified the potential of using calcinated AASR to manufacture geopolymer products upon proper calcination process.