Preparation and strength property of autoclaved bricks from electrolytic manganese residue

To reduce the Electrolytic manganese residue (EMR) hazard to environment and invent new construction materials, an autoclaved process was employed to prepare non-fired bricks with EMR, gelling agent (lime or cement) and aggregate (sand and stone clips) as raw materials. Based on analysis of EMR characteristics, lime was added. The influence of mix proportion of gelling agent including lime and ordinary Portland cement (OPC), and the forming pressure on strength of the autoclaved bricks was investigated. The results showed the optimal mix is 30% EMR, 10.5% OPC and 59.5% aggregate, and the optimal forming pressure and steaming condition are 25 MPa and 1.2 MPa for 8 h, respectively. The bricks from the pilot-scale experiment were well conformed to autoclaved lime-sand bricks GB 11945-1999 for MU 25 grade. Leaching tests undertaken on the autoclaved bricks showed that the concentrations of heavy metals in the leachates were largely inside the regulatory limits so bricks from EMR can be regarded as non-hazardous material.