The most widely applied method for the disposal of waste materials, including sludges, dusts, scales, leachable slags from smelting or melting operations, and residues from the combustion of organic materials including municipal wastes, is to inter the materials in an appropriate landfill. Small quantities of some wastes are encapsulated within Portland cement or sulfur, and then consigned to a landfill. However, landfill disposal of wastes is at best a short-term solution, because landfills are nearing capacity and new landfills are difficult to establish. A promising and technically viable permanent solution to the problem is to melt the waste materials to produce inherently non- polluting amorphous or crystalline mixtures of inorganic oxide products, similar to slags produced by various metal industries. These products may be useful as aggregate for bituminous or Portland cement concrete, for grit blasting, as road building and construction ballast, and in the manufacture of mineral wool instead of landfill disposal.
In 1984, the ASME Research Committee on Industrial and Municipal Waste asked the U.S. Bureau of Mines about the feasibility of melting (vitrifying) ash residues produced by the combustion of municipal wastes. A demonstration melting test of dry