Swelling of Iron Ore Pellets by Statistical Design of Experiment

Abstract

In the present investigation an attempt has been made to study the swelling behaviour of iron oxide pellets made from chemically pure iron oxide and natural ore from Bailadila Mines. The tests were conducted under isothermal conditions. The variable parameters studied are reduction temperature, time, partial pressure of H₂ and CO, flow rate, firing temperature, firing time, porosity of pellet and additive like CaO, MgO, SiO₂ and Al₂O₂. The experiments were statistically designed so that the effect of each variable and interactional effect of different variables can be quantitatively assessed. Swelling index of the pellet has been found to be maximum at a critical rate of reduction, which is controlled by reduction temperature, reducing gases, partial pressure and flow rate. Firing temperature and time have been found to affect swelling index of pellet by affecting porosity. Addition of CaO, MgO and SiO₂ has been found to decrease the swelling index of the pellet. The application of the results to practical steel makers has also been discussed.