Abstract: Tailings discarded after direct reduction-concentration process was used as principal material ,adding sewage sludge,to sinter lightweight ceramsite. The optimized preparation conditions were selected. The impacts of main factors ( preheating temperature, preheating time, sintering temperature, sintering time，and material ratio) on characteristics of ceramsite (apparent density, bulk density, water absorption and crushing strength) were studied. The results show that the optimized mass ratio of tailings to sewage sludge was that tailings∶sewage sludge=95∶5. The optimized preparation conditions were as follows: preheating temperature 550 ℃, preheating time 30 min, sintering temperature 1 110 ℃, and the sintering time 6 min. Under these conditions, the characteristics of ceramsite were obtained as follows: apparent density1.365 g/cm3, bulk density0.672 g/cm3, 1 h water absorption3.50% , crushing strength 220 N,cylinder compressive strength 3.5 MPa.

Key words: Tailings, Sewage sludge, Direct reduction, Lightweight ceramsite