Self-stabilisation of high-temperature calcined electrolytic manganese residue in mortar

High temperature calcination and mechanical ball milling are the most effective methods for increasing the volcanic ash activity of electrolytic manganese residues (EMR) and pretreating hazardous substances (NH3-N and Mn2+). In this study, the effects of different calcination temperatures (200, 400, 600, 800, and 1000 °C) and different EMR dosages (10, 15, and 20 %) on the mechanical properties, microscopic properties, and leaching toxicity of mortar were investigated. The results showed that the compressive strength of the prepared mortar mixture at different ages increased by 13.14 % to 24.5 % at a calcination temperature of 800 °C and dosage of 10 % EMR. Microscopic tests were performed to characterise the distribution of ettringite and calcium silicate hydrate gels on the surface of the mixed mortar. X-ray photoelectron spectroscopy and leaching toxicity analysis revealed the presence of EMR in the form of CaSiO3, MnO(OH)2, and M−NH4+. The leaching toxicity of Mn2+ and NH3-N in the EMR-blended mortar was significantly lower than the emission standards. The use of EMR in construction materials assists in resource utilisation and environmental protection.