The recycling of waste foundry sand

Sand is the principal moulding medium used in making casting moulds and cores within the foundry industry. It is estimated that for every tonne of casting produced a tonne of waste sand is generated. This has resulted in a huge number of waste tips containing potentially valuable materials, namely silica sand, but also specialist sands, clay, coal, and a variety of metals. However, owing to increasing raw material and disposal costs, foundries have now been forced to develop new technologies to enable this waste material to be recycled. This work initially involved characterising foundry tip material and then developing a variety of processing methods. The end products from this processing, depending on the type and degree of treatment, can either be recycled directly back into the foundry, or act as raw feed stocks for other processes such as the manufacture of cement and asphalt. This paper presents the results of the characterisation study, establishes which materials can be recycled, evaluates the most suitable mineral processing technologies available and reviews the current alternative uses for waste foundry material. This work is part of a larger government funded project involving several UK greensand foundries.