Abstract: A centrifugal separator comprising an upright cylindrical drum having top and bottom walls which extend radially inward from its cylindrical side walls. The upper annular wall has a center aperture greater in diameter than the corresponding center aperture of the lower annular wall. A liquid slurry is delivered to the interior of the drum as it rotates, forcing separation of solid particles as they migrate outwardly toward the drum side walls. Excess liquid escapes over the top of the drum through the opening at the center of the upper annular wall. An independently rotatable scraper blade is coaxially mounted with the drum and is located adjacent the interior side walls. The scraper blade can be independently braked to assist in removing solid materials from the rotating side walls while drum rotation is being terminated.

Abstract: A reclaiming system for used foundry sand containing a sodium silicate (water glass) binder. The resulting chunks of sand and binder are disintegrated by mechanical crushing in a water wash. A primary slurry containing discrete particles of sand and both dissolved and suspended binder is conveyed to a settling tank where the sand settles from the slurry. The heavier particles of sand are removed by a ladder conveyer, which allows liquid to drain from the sand as it is being elevated. The sand is dried in rotary drum dryers, being subjected to a constant flow of heated air. The remaining secondary fluid, containing particles of binder, is directed to a centrifugal separator, where the suspended materials such as binder particles are removed from the liquid. The liquid is then recirculated in the system, eliminating discharge of liquid or the need for substantial replenishing of liquid during the process.