Process of reclaiming used foundry sand

摘要

Used foundry sand is reclaimed by crushing the sand and separating both metallic material and at least a portion of the unwanted non-metallic portion of the sand, then heating the sand to a temperature of about 1400 DEG F. for burning off the foreign material and causing the sand particles to pass through a strong expansion phase somewhere above 1000 DEG F. and passing through a contractual phase at a higher temperature to thereby cause the foreign material to be cracked or otherwise parted from the particles and the sand particles become increasingly thermally stable from subsequent reuse as clean sand. The heated sand is then cooled to about 400 DEG -500 DEG F. The process includes the utilization of some of the heat of the thermal furnace for a shell coating operation. The process also includes classifying the cooled sand as to size particles and then taking the agglomerated coarser particles and subjecting them to further cooling and a sand scrubbing operation for further reduction to particle size. The reduced and cleaned sand is combined with new sand as may be required to meet screen specifications. The sand mixtures may then be used as a replacement for new sand. They may also be blended, heated, and coated with bonding materials for reuse.