Extraction of Chromium as Sodium Chromate from Stainless Steel Dust.

The objective of this investigation was to recover chromium as sodium chromate of 99.5% purity from stainless steel dust. The dust contains 7.72% chromium obtained from stainless steel processing plants. The stainless steel dust mostly contained iron in oxide form along with chromium, nickel (1.71%) and manganese (3.55%). The steel dust was roasted with soda ash followed by water leaching to recover the major constituent chromium. It was found that roasting at 1073 K for 90 minutes resulted in maximum (95%) chromium recovery. Kinetics of sodium chromate formation followed a topochemical model involving chemical reactions at the surface with activation energy of 39 kJmol-1. TG/DTA, XRD phase identification and SEM microphotographs confirmed the experimental observation and the mode of reaction. [ABSTRACT FROM AUTHOR]