Within a plasma converter, waste is converted into basic elements as it passes under a large plasma torch within a containment vessel. Gaseous elements are purified then processed into a fuel known as syngas, a product similar to natural gas. Heavier elements collect in the bottom of the vessel as a molten slag which can then be cooled and turned into building materials. The slag can be processed into different materials depending on how it is cooled. Set to dry slowly, it will become a dark, obsidian-like glassy material. Water cooling results in a sandy product which metal ingots may be sifted out of. Another method flosses the slag into a fiberglass that is highly heat resistant. Each step also produces heat that can be used to create electricity and warm the facility. ( http://science.howstuffworks.com/environmental/energy/plasma-converter.htm )