Improvement of Ash Surface-Melt Furnace and Utilization of the Slag

Japanese Ministry of Health and Welfare has issued a guideline for municipal solid waste incinerators to install ash melting furnaces for the purpose of relieving landfill shortages and recycling resources. Since there are many furnaces without power generation units, fossil-fuel burning furnaces are commonly used, and there is an increasing demand for technologies to improve fuel consumption and slag quality. As for improving fuel consumption, we have conducted several tests with furnaces of various designs, improved burners and comparisons of liquid and gaseous fuels. We also have done tests of controlling ash particle sizes. The tests results are: 280 liters of liquid fuel melted one ton of ash, and gas fuel equivalent of 230 liters of liquid melted one ton of ash, using continuous-operation pusher-feed surface-melting furnace. As for improved slag condition, we have done tests melting bottom ash only, mixtures of bottom ash and fly ash, and mixtures of bottom ash and crushed incombustibles (residues from screening at materials recycling facilities). We analyzed the slag from each source, and studied the feasibility of using it to make bricks and interlocking blocks.