Swelling of Iron Ore Pellets Subjected to Gaseous Reduction.

The effect of gaseous reduction on the swelling of iron ore pellets was investigated by means of three different kinds of tests, namely, stepped isothermal, continuous isothermal, and programmed. The isothermal reductions caused more swelling than the programmed reduction, particularly at 1,000 degree C and when the basicity was between 0. 3 and 0. 5. Under these conditions, programmed reduction often produced sponge iron pellets with volume contraction, resulting in sponge iron with compact structure. The results show that the best swelling test is that in which the pellets are reduced isothermally at a high temperature.