A research on ceramsite obtained from blast furnace slag and sewage sludge
In order to solve disposal problem of solid waste, blast furnace slag (BFS) and sewage sludge (SS) were tested as components for producing ceramsite. This study investigated the feasibility of that at different preheating and sintering temperature and duration and different mass ratios (BFS: SS: clay). The results show that the optimal preheating temperature and duration were 400°C and 20 min and that of sintering were 1000°C and 20 min. When the content of BFS increased and that of SS declined, the bulk and apparent density gradually increased while the 1 h water adsorption rate relatively decreased. The ceramsite produced had very good characteristics of solidifying heavy metal and the values of Cd, Cr and Sn met China national standard (GB5085.3-2007); the leaching dose of heavy metals reached minimum at 1100°C. With the increasing of sintering temperature and duration, the gas was gradually released from the ceramsite to form many pores and the glass phase and smooth surface appeared in the ceramsite. The turning point of sintering temperature and duration were 1000°C and 20 min. The conclusions reveal that it is feasible to produce ceramsite by using blast furnace slag and sewage sludge.
Key words: Ceramsite, blast furnace slag, sewage sludge, preheating process, sintering process.