Steel-Making Slag Groundcover Use – Is Chromium of Concern?

Electric-arc furnace (EAF) slag is a rock-like material generated during the steel-making process and often used for groundcover, akin to granite rocks around our homes and residences. An ad hoc committee of the National Academies of Sciences, Engineering, and Medicine (NASEM) is conducting data collection to assess human health risks associated with the unencapsulated use of this slag. Chromium has been identified by the US EPA and the NASEM committee as a potential element of concern within this slag type.

The National Slag Association (NSA) is an association of blast and steel-furnace operators that advocates for safe use of slag produced during steel making, and they are closely following the NASEM activities and data interpretation. The NSA and member facilities also have commissioned slag characterization and risk assessment studies outside of NASEM and US EPA activities. Environmental Standards has been supporting one of these studies through the Edward C. Levy Company with the design, management, and analysis of laboratory studies focused on evaluating whether chromium is present in the hexavalent form.  Included in this work is the use of XANES spectroscopy to evaluate the valence states of chromium within the slag matrix. XANES spectroscopy   provides non-destructive analysis and is considered the most-definitive evaluation of elemental speciation. Preliminary XANES data from this research indicate there is little, if any, hexavalent chromium in these EAF slags. Further work will measure total available, as well as soluble, exchangeable, and total hexavalent chromium leached from EAF slag. The ultimate objective of this research is to evaluate if standard laboratory digestion and test methods used to quantify total hexavalent chromium produce biased results due to the complex matrix present in EAF slag.