Immobilization of CR (VI) in ferrochrome flue dust

Chromite ore (Fe, Mg)O(Cr, Fe, Al)2O3 is the main raw material for the production of ferrochrome metal. During the production of ferrochrome enormous quantities of slag and furnace flue dust are generated as waste material. Flue dusts are fine solid particles released into environment during the ferrochrome metal production. These flue dust waste of ferrochrome industries, contain not only chromite minerals but also important source of pollution due to its high levels of extractable toxic elemental content which are considered to be hazardous materials by USEPA as well as EU if left untreated, stockpiled or land filled. Immobilization of hexavalent chromium in these flue dust waste is highly essential for safe to dispose to the environment or further utilization as land fill. Hence, the objective of this present study is to minimize the chromium concentration of the flue dust generated from ferrochrome industry. In order to understand the nature of these wastes and to develop a process for Immobilization of hexavalent chromium, a detail characterization by optical microscope and XRD has been carried out. The Immobilization of hexavalent chromium studies were carried out by mechnochemical activation of the flue dust with and with out the additives. Optical microscopic studies revealed that the flue dust sample consists of three different mineral phases that is silicate phase quartz, chromite phase and a metallic phase that is ferrochrome. A better result of hexavalent chromium immobilization was found when Magnesium Oxide was used as an activator