Studies on plasma processing of blue dust

Abstract

A huge amount of blue dust is produced during mining operations of iron ore and mostly dumped at mines site. Till date no measure action is being taken for utilization of blue dust for extraction of metallic iron. Generally metallic iron is produced through BFO and DRI processes where particle/ore size and reductant is the most important factor considered for BF charge. The present piece of research work is aimed at use of blue dust for production of metallic iron. A newly emerging technology i.e. plasma smelting process is adopted for reduction of blue dust. Blue dust of average particle size about 100-150 micron is taken and carbon (pet coke) of 5, 10, 12, 15 and 20 percent is thoroughly mixed, used as feed material. It is charged to a 35 KW dc arc plasma furnace and smelted for different time lengths i.e. 10, 17 and 20min using argon and nitrogen, separately, as plasma forming gas. The degree of metallization, amount of recovery for all samples is measured. Maximum of 86% recovery and 98% metallization is achieved. It is observed that use of nitrogen as plasma forming gas increases the rate of recovery than that of argon plasma, due to high energy flux of nitrogen gas which increases the enthalpy due to its diatomicity. The X-ray diffraction analysis shows the presence of ferrite and cementite phases in the smelted product. Variation of microstructure is observed with the samples. The hardness measurement of different phases on the sample ensured the presence of ferrite, pearlite and cementite phases depending on smelting condition.