(Bragança et al.,2006)

There are currently 480 foundries operating in the UK (CMF, 2017), primarily based in the Midlands, South and East Yorkshire. The most common production process used is sand casting, where sand is mixed with clay (“greensand”) or a synthetic binder and additives (“chemically bonded”) to make an expendable mould used for a single casting. Foundry sand is typically re-used multiple times to make new moulds until it eventually degrades due to changes in grain shape or size.

The composition of the foundry sand waste varies depending on the binding system used. Greensand waste is approximately 85% silica sand, 10% bentonite clay, and 5% coal dust. The main components of chemically bonded sand are typically 97% silica sand with the remainder being binders, catalysts and hardeners (Winkler and Bolshakov, 2000). Both wastes can also contain varying amounts of metal contamination from the casting process.

Of the total foundry waste generated by the industry, approximately 30% goes to re-use applications and 70% to landfill or stockpiles (Bridgewood and McKie, 2009).