Recovery of Bentonite and Other Materials from Foundry Waste Streams

摘要

Today's era of ever tightening environmental regulations governing air quality and foundry waste management coupled with increasing raw material prices, transportation, and disposal costs present a challenging obsticle for the future of the metalcasting industry. There is a strong, new movement in foundry management that values sustainablity and material recovery from waste streams. These foundry waste streams still contain viable elements that are lost among the other undesired constituents. A new and innovative process aims to eliminate and aleve these environmental pressures to increase foundry efficiencies, reduce waste, and the costs associated with disposal without sacrificing casting quality. The waste materials from foundry green sand systems can now be turned into a valuable new resource. This innovative new process recovers the bentonite, carbons, and bonded green sand from the waste streams of a foundry and makes them available for reintroduction. All can be made available to improve molding sand properties and improve molding sand performance. The reintroduced bentonite and carbon can replace an equivalent or more of powder bond added to a foundry green sand system. The bentonite exhibits improved molding sand properties because the wet bentonite recovered has an excellent dispersibility. The bonded molding sand grains are provided with a uniform layer of binder and organics that result in an improved casting surface quality. This dispersion results in outstanding mold compaction and shape stability of the prepared molds. The packing density and mold strength are kept at a uniformly high level. Even complex contours with high mold shape can be improved resulting in scrap reduction and improved casting efficiency.