high temperature and slag

There are endless varieties of gasifiers that have been produced over the years. Gasification is very much an art and the equipment is tailored to the feedstocks that are put into it. Most gasifiers have been used for either coal or biomass and have been optimized for those purposes. Generally speaking coal gasification is done in very large industrial facilities while biomass gasification is done on a much smaller scale, and is often done by hobbyists and tinkerers in their garage as well as in developing world countries.

I intend to do a review of gasification technologies at some point.

The challenge in gasifying garbage (municipal solid waste or MSW) is the heterogeneous nature of the materials. MSW by its nature is composed of a huge variety of materials ranging from plastics and papers to metals, glass, construction debris, and many others in varying sizes and moisture contents. Traditional gasifiers cannot handle such mixed waste. In order to reliably process MSW the gasifier needs to operate at much higher temperatures and throughputs. Basically the temperature needs to be high enough that it can reliably melt all the metals and glass that go in. Gasifiers that melt metals and ashes are called "slagging" gasifiers because the melted materials from glass, mineral, stone, and metal becomes molten fluid in the gasifier and will pour out a tap hole and be cooled. Once cooled the molt is called slag and it forms vitrified glass. The slag is very stable and in the USA must pass EPA TCLP leachability tests which test for a variety of potential toxins that may potentially leach out. Slag from high temperature gasifiers is remarakbly stable and clean. The high temperatures break down organic hazards and the glass itself seals up many other dangers such as volatile metals like mercury, lead and cadmium.

Insert details on TCLP tests.

Insert characteristics of Slag. Review New York harbor sludge.