Metallic Characterization of Foundry By-Products per Waste Streams and Leaching Protocols

In the United States, foundry facilities produce huge quantities of by-products to be disposed of annually. These by-products are broadly divided into three waste streams: sand, dust, and slag. To characterize foundry by-products in terms of waste streams helps beneficially manage and reuse foundry by-products based on individual environmental characteristics. One thousand one hundred eighty two data sets addressing bulk and leaching characterization of up to 24 metallic elements in sand, dust, and slag are collected and assessed using statistical methodologies. Findings indicate that sand is not hazardous with high confidence per metallic elements, and a leaching program is not mandatory in assessing whether sand is hazardous or not regarding metallic elements. No evidence indicates that dust and slag are nonhazardous materials. Only a fraction of metallic elements are extracted from as-received waste streams. Through comparisons of statistical parameters including estimated means, 95th percentiles and data distributions, sand is found less contaminated by most metallic elements than dust and slag, but metallic elements in sand leachate are in the similar levels as those in dust and slag leachates. Fe, Zn, and Al are highly concentrated in dust and slag on average, which suggests their potential reclamations.