Studies on Carbothermic Reduction of Chromite in the Presence of FeOx

Abstract: Direct chromium alloying by chromite ore is a promising technology for producing Crcontainingsteels, as the ferrochrome production process and the chromium alloying processare integrated into a single step, which has the potential of saving energy and raw materials.In this work Thermogravimetric Analysis experiments and induction furnace experiments (upto 80-kg scale) have been carried out to investigate the carbothermic reduction process ofchromite in the presence of FeOx (iron, mill scale or magnetite). The aims are to investigatethe effect of FeOx on the carbothermic reduction of chromite and to explore the potential ofdirectly alloying steel with chromium by the designed alloying precursor ‘chromite ore +FeOx + carbonaceous material’.The results from the Thermogravimetric Analysis experiments show that FeOx can enhancethe carbothermic reduction of chromite and the enhancing effect increases when increasedamounts of FeOx are added to the chromite. The enhancing effect is attributed to the presenceof added metallic iron or the metallic iron reduced from mill scale or magnetite, which candecrease the activity of chromium by having chromium dissolve in the iron in situ. The resultsfrom the induction furnace experiments show that the steel can be directly alloyed withchromium by using the designed alloying precursor ‘chromite ore + mill scale + petroleumcoke’ and the chromium yield from chromite ore increases when increased amounts of millscale are added to the alloying precursor.The designed alloying precursor, on one hand, can be potentially used to directly alloy steelwith chromium in the Electric Arc Furnace steelmaking process and, on the other hand, can bepotentially used to produce Cr pre-alloyed iron powder or Cr pre-alloyed Direct Reduced Ironby the solid-state reduction process. The proposed applications have the potential to improvethe raw materials efficiency and energy efficiency.