EPS slag assessment

Environmental and Process Solutions (EPS) requested Softchem to assess a slag that will be produced in a proposed process involving the smelting of a chrome chemicals plant residue that is currently stored in a lined facility at Lanxess in Newcastle in terms of the Department of Water Affairs and Forestry's minimum requirements for the handling, classification and disposal of hazardous waste (DWAF,1998), and to suggest suitable management options.

Using the minimum requirements' prescribed methods, including the application of the toxicity characteristic leaching procedure (TCLP) and the South African acid rain leaching procedure (ARLP) to two samples of the slag, the Lanxess slag is generally classified as a hazard rating II waste. However, the amounts of heavy metals leached are low and significant quantities can be delisted for disposal either to a mono-disposal or co-disposal landfill with a minimum classification of GMB+. In addition, the actual leaching pattern of the slag could be significantly different from that predicted by the aggressive TCLP and ARLP tests and it is recommended that the leach studies be extended to a study of leaching with TCLP solution number 1 and distilled water.

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