HAZARDOUS WASTE MINIMIZATION: PART VI Waste Minimization in the Foundry Industry

B e foundry industry is a major consumer of waste materials (scrap). Udortunately, the recycling of these waste materials can result in the generation of hazardous wastes that must be properly managed at a significant cost. Tdis article focuses on two waste streams in the foundry industry; calcium carbide desulfurization slag and melt emission control residuals. The author presents an overview of how foundries have evaluated different waste management options with the ultimate goal of " i z i. the generation o f hazardous waste. Although there may be differences in certain operations, basic foundry pro-cesses vary only slightly from one foundry to another. All foundry opera-tions produce castings by pouring mol-ten metal into molds, often consisting of molding sand and core sand. Once the casting has hardened, it is separat-ed from the molding and core materials in the shakeout process. The castings are cleaned, inspected, and then shipped for delivery. Figure 1 is a sche-matic of a typical foundry process, showing both finished product and the types of air emissions and wastes gen-erated.' Foundries are major consumers of waste materials. Scrap iron and steel are a major source of raw materials, amounting to 85 percent or more of the ten million tons of ferrous castings pro-duced annually. Reclaimed copper, aluminum, lead, tin, zinc, and other metals are also recycled to a major ex-tent in making castings. The recycled cast product is evident everywhere in the artifads and machines which con-stitute man's material civilization. In addition, other residues from manufac-turing operations, such as asphalts, pitches, sugars, resins, and cellulose-Gpyright 1988-AFCA waste, are reused in the foundry pro-cesses