Classification and mixing of sands

摘要

This design is concerned with the production of high quality sand. It may classify the raw material into three grades, namely coarse (0.5-2 mm), medium (0.25-0.5) and fine, (0.06-0.25) by a process which is not influenced by variations of the raw material. The final product may be obtained by mixing proportions from the classifiers to provide, preferably two mixtures of different specifications in which the coarse fraction is the principal ingredient. Any surplus sand may be dumped for subsequent disposal. The surplus sand may consist of fine and medium fractions which may be thickened in two steps and dewatered before dumping. The installation may consist of a sieve (2) which passes sand in a range up to 2 mm to coarse classifier (5). The coarse product may pass to dewatering units (34) and (36) and lighter fractions may pass, via hydrocyclone (9'), to the medium classifier (14). Medium products may pass to funnel (15) and from there to dewatering units. Fine fractions may overflow from to funnel (51) via hydrocyclone (9). Overflow from these funnels may pass to a dewatering unit (23) and then to the top of a tower (27) from where hydrocyclone (25) may pass it to dump (26).