A New Fly Ash Treatment Proposal and Practical Tests of Pilot Plants

Fly ash generated from municipal solid waste incinerators is designated as specially controlled waste in Japan, and there is a legal obligation to make it harmless before disposal. Technologies for making wastes harmless require excellent reliability and environmental safety. Slag is generated as a byproduct of various types of melting furnaces, and technologies are required for effectively recycling it as a useful resource. This paper reports new technologies developed for treating incinerator fly ash and making them harmless by applying metal smelting technologies. The paper also presents a new technology for mixed, simultaneous treatment of fly ash and slag. In the newly developed fly ash treatment process, fly ash is formed into pellets, and baked in a rotary kiln to make it harmless. The baked product is recovered as a material that can be easily used effectively in various applications. In addition, secondary fly ash is treated to recover sub-materials for metal smelting. These technologies are characterized by the fact that the baked products are obtained as pellets that have excellent environmental safety and enhanced strength, and secondary fly ash is also effectively recycled as a smelting material. Experiments were performed on fly ash of various compositions using experimental equipment that had a treatment capacity of 100 kg/hour.