Mechanical activation of siliceous tailings and its application as cement admixtures

Abstract

• Siliceous tailings were mechanically activated using high-energy grinding. • Activated tailings T3 showed a superior pozzolanic activity. • Cements produced using T3 can meet the requirement of P•O 52.5 Portland cement. • Bulk and green disposal of siliceous tailings can be available by using this method. • This method can bring great environmental and economic benefits. Mineral processing tailings have increased dramatically, owing to the growing demands for minerals and metals over the past decades. These tailings pose significant hazards to local environments and human health. In this paper, the mechanical activation method was applied for improving the pozzolanic activity of siliceous tailings, and the activated siliceous tailings were used as admixtures in cement production. The geometrical characteristics, surface morphology, crystal structure, and pozzolanic activity of activated siliceous tailings were investigated systematically. Mechanical activation can reduce the particle size of tailings and increase the BET specific surface area up to 11.67 m 2 /g. The pozzolanic activity of activated tailings was enhanced to 81.15%. It is demonstrated that calcium silicate hydrate gels, ettringite (AFt), and hydrotalcite were the main hydrated products of activated tailings. The activated tailings were mixed in proportion with P•O 52.5 Portland cement to produce new cement. The new cement produced using 8% activated tailings can meet the requirement of P•O 52.5 Portland cement, exhibiting superior profits. This is a green method for bulk handling siliceous tailings and substituting Ordinary Portland Cement.