Reduction of ilmenite with simultaneous lignite gasification in a fluidized bed reactor

An altern ative process for th e red uction of ilmenite mineral using a low-cost reductant (lignite) in a fluidized bed is re­ ported in thi s paper. An important correlat ion has been demonstrated experimentally between th e concentration of reducing gases (CO and H2) in th e reactor and the ratio of lignite to air feed rates. In order to ensure adequate red uci ng conditions in­ side th e reac tor, th e ai rfl ow rates, maintained at much less th an stoichi ometric requirements (fo r complete co mbustion) of th e fuel, are represented by th e air factor. Experiments have been performed in th e presence of both an in ert (sand) and an active (ilmenite) bed. The evolution of solid-phase transformati on with redu cti on time has been interpreted usin g the X-ray diffrac ti on method. The presence of magneti c phase enh ances the ex te nt o f iron removal from th e reduced ilmenite by acid leaching. The titanium mineral ilmenite is the major commercially viable raw material for the manufacture of several inorganic chemicals and advanced materi als such as Ti02, TiCI4 , titanates, and titanium, etc. India has th e enviable position of having more than ] 5 % of th e global premier grade resources of ilmenite. The state wise distribution of ilmenite resources along with their composition are reported I in literature . Ilmenite mineral is upgraded in two or more stages in the value addition chain. The first stage of value addition is brought about by th e enrichment of the titanium oxide content of the mineral from 40-60% to around 92-95% by the elimination of the iron component and other minor impurities such as manganese. The various processes I adopted by manufacturing plants in Indi a to accomplish the first stage of upgradation to synthetic rutile is described in Table I . In these processes, the crucial operation of reducing ilmenite is carried out in rotary kilns employing high rank coal or coke as the reductant. Fuel oil is also used to provide the required thermal energy. Not only does the rotary kiln operation suffer from very low productivity but it al so has the additional disadvantage of poor efficiency and non-uniform product characteristics. However, fluidized bed reactors have no such drawbacks and provide a near ideal solid-gas contacting mode due to