Production of Clay Coated Lightweight Fill Materials From Air Pollution Control Residues (APCR)

摘要

Air pollution control residues (APCr) from energy-from-waste are classified as hazardous due to theirudhigh heavy metal content and alkalinity. Recycling attempts using thermal treatment to produce audceramic material known as lightweight aggregate have been successful in incorporating a maximumudof 10% of APCr in the final product’s structure. The aim of this work was to increase this incorporationudby producing macro-encapsulated APCr granules with a clay coating. APCr has been washed withuddeionized water, milled and mixed with different concentrations of sodium silicate to form intoudgranules. Sodium silicate solution was added to the mix to enhance the content of silicate and flux.udThe green pellets were coated with clay and sintered in a laboratory furnace at 1150 °C. The effectudof addition of sodium silicate on particle density, water absorption and compressive strength hasudbeen discussed. Leaching behaviour of heavy metals and soluble anions from the sintered granuleudwas examined according to BS EN 12457. Optical micrographs of the sintered products wereudinvestigated to reveal the microstructure of the binding interface between APCr and clay coating.udThe results showed that incorporation of up to 30% of APCr in the structure of sintered granules isudpossible. The proposed clay coating technique is simple and can reduce the leaching behaviour ofudhazardous waste.