Environmental Characterization of Two Chromium-based Industrial Waste Contaminated Sites of India

Metal Contamination from Chromite Ore Processing Residue (COPR; a Cr-containing industrial solid residue) disposal sites, is documented to be a serious environmental and health concern. Unbridled deposition of COPR, which undergoes continuous weathering reactions, leads to release highly toxic and mobile Cr(VI) in to the environment. The variances in mineralogical and chemical properties amongst the materials of COPR have formidable implication for its leaching behaviour and consequently for treating them. Old COPR sites (>40 and <180 years) located in the world's temperate zone have been studied extensively. Current study investigates the mineralogical composition and the geochemistry of COPR sampled from two abandoned dumpsites (Young; <30 years) of India. Chromium speciation and leaching studies showed Cr(VI) concentrations up to 20% of total Cr content in certain samples. X-ray diffraction studies revealed that all major minerals reported in COPR studies across the world were identified in the collected samples. Additionally, well soluble forms of chromium (Na 2 CrO 4 ) were identified to be present. Most of the Cr(VI) was observed to be bound in minerals such as Calcium Aluminum Chromium Oxide Hydrate (CAC) and Ettingite. Based on high Cr content, it is concluded that the high temperature oxidative roasting technique employed by Indian industries during CrO 4 2- extraction process is extremely inefficient.