Stabilisation of Cr(VI) in stainless steel plant dust through sintering using silica-rich clay.

Stainless steel plant dust is considered a hazardous waste due to the fact that it contains significant levels of Cr(VI) and other heavy metals such as lead and zinc. It should therefore be treated before being stockpiled or land filled. Solidification/stabilisation processes are effective techniques for the immobilisation of heavy metals. This paper consequently describes an investigation into the stabilisation of Cr(VI) in stainless steel plant dust with silica-rich clay in a sintering process. The results indicate that Cr(VI) in the stainless steel dust can be stabilised in a 50 mass% dust:50 mass% clay mixture at an optimum sintering temperature of 1100 degrees C, and minimum sintering time of 5h. Chromium emission during the sintering process was found to be low, and within environmental limits.