An investigation aboutoxidation of magnetite to hematite during preheating of an iron ore concentrate pellet using a DOE method

Sintering of iron ore pellets consists of two stages; Preheating and firing. The Oxidation of magnetite to hematite is the distinguished reaction which takesplace mainly in this stage. Since reducibility of hematite is pronouncedly higher than magnetite، it is necessary to adjust the sintering conditions so that the maximum oxidation takes place without undesirable sintering phenomena in this stage. Present study deals with the evaluation of the most influential parameters affecting the oxidation of iron ore concentrate pellets، i. e.، preheating temperature and time. By application of a two factor and four level full factorial design of experiment (DOE) a model in the form of R=37. 5177 – 2. 3187T2 + 16. 058T – 5. 372t2 + 26. 762t has been obtained to describe the effects of preheating temperature (T) and time (t). With regard to this equation، almost same influencesare anticipated with regard to the preheating temperature and time. Iso-efficiency contour based on the aforementioned factors show that optimum condition for getting oxidation efficiencies of a desirable level around 80% is T=800°C and t=20min