from external sources (including ferrous material from recycled cars, appliances, and scrap steel from other manufactur- ing operations etc.). Alloying elements, are then added to the melt to meet the specifi c chemistry requirements. Recyclable Castings: Metalcasting
facilities convert unwanted scrap metal into valuable castings with a variety of applications. T ose components, once they are no longer needed, will become the scrap that may head to another metalcasting facility for a second or third life. “Metal doesn’t have a memory,” said
Sigworth. “It doesn’t kno w or care it was a casting yesterday.”
Reclaiming and Reusing Sand
Foundry sand, which is used by 60% of metalcasters to make molds and cores in a variety of metalcast- ing processes, represents a signifi cant industrial byproduct. Unlike metal, which has been recycled for centuries, foundry sand has become a target of reclamation and recycling eff orts in the last 20-30 years. Due to increasing regulatory control and disposal costs, metalcasters have reduced the amount of sand headed to landfi lls. T e industry discards between 5-8
million tons of sand no longer suitable for making quality castings annually. However, according to a recent industry study, prior to being discarded, the aver- age sand grain is reclaimed and reused by the metalcaster an average of eight times. Additionally, approximately 30% of
Reclamation of sand used in cores and molds has increased dramatically in the last 30 years.
in dross and slag. Depending on the casting, machining may result in metal loss. But for the large majority of casting operations, somewhere in the neighborhood of 95% of the as-cast part will eventually exit the metalcast- ing facility as the fi nished casting. Costs are involved in processing and
reusing metal, but the overall effi ciency of the operation means that waste remains relatively small. Also, because metalcast- ers have been focused on maximizing metal usage for decades, internal recy- cling is approaching its peak.
“We’re pretty optimized now,”
Muratore said. “T ere’s only so much you can do and the industry is already recycling and reusing a tremendous amount of material.” In a typical melt, aluminum cast-
ing facilities use between 40-60% scrap from within the facility (gating, riserings, scrap castings, etc.), with the remaining aluminum coming from ingots that often contain a considerable amount of recycled material. In general, ferrous metalcasters use between 30- 50% internal scrap and 40-50% scrap
38 | METAL CASTING DESIGN & PURCHASING | May/Jun 2014
foundry sands are reused in non-landfi ll applications. T ese uses include geo- technical fi lls, road sub-base, embank- ment construction, aggregate in asphalt, soil additives and replacement for silica in cement. Despite the advancement of recycling initiatives into higher-end recycling, it is not necessarily a revenue- generating endeavor. Processing costs to get the material to “product quality” typically consume any margin in the sale price of the material. However, the advantage of minimizing disposal costs, in addition to the environmental benefi ts, makes this approach more preferred to disposal. “Sand as a raw material for construc-
tion applications is typically not a high dollar expense for contractors,” Lenahan
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