A novel reductive alkali roasting of chromite ores for carcinogen-free Cr-ion extraction of chromium oxide (CrO) - A clean route to chromium product manufacturing!

A novel reduction reaction for extracting CrO from chromite ores is demonstrated by excluding the formation of carcinogenic chromate (Cr) intermediates. We have investigated in detail the underpinning high-temperature reduction reaction: FeCrO+NaCO+2[C]=[Fe]+NaCrO+3CO, which defines the process chemistry for the formation of sodium chromite (NaCrO) as an intermediate product for CrO extraction. After high-temperature reduction, the magnetic separation, aqueous and acid leaching of reaction products yielded 81 wt% and 70 wt% pure CrO from low (∼4 wt%) and high (>8 wt%) silica-containing chromite ores, respectively.