Especially in the foundry field and, indeed, whenever sand castings are made, following the casting process a used sand becomes available which may have to be reprocessed, inter alia, to remove contaminants, and may have to be combined with new sand or fresh sand and, in some cases, with special sands for particular purposes in the foundry arts, before the sand is reused for the production of molds and the like.
Apparatus for the processing of sand, both used sand and new sand, generally comprises a housing having a sand inlet and a sand outlet.
The characteristics of the treated sand which are important are a uniform particle size, a freedom from detrimental contaminants, the presence of binder residues which may be advantageous, and, in the case of used sands, a freedom from dust, slime and the like. The product should also be free from large agglomerates and metal sputterings from the casting process as well as other impurities which may be detrimental to a subsequent casting process.
In the past the apparatus has been designed to free the sand from contaminants and thus prepare the sand for reuse, both in the case of used sand and in the case of mixtures of used sand with fresh or new sand.
By and large prior apparatuses for this purpose have proved to be unsatisfactory because the sand during the process was subjected to different temperatures and different humidity levels so that an optimal treatment could not be assured. Further a homogeneous reproducible product could not be ensured.