Improved removal of zinc from blast furnace sludge by particle size separation and microwave heating

Based on elemental distribution, BFS can be divided into two parts: one with zinc content of about 0.108 wt.% (coarse fraction with particle size greater than 63 µm), and the other with higher zinc content, of about 1.02 wt.% (fine fraction with particle size less than 63 µm). The microwave tests indicated that zinc content in the fine fraction of the BFS decreased from 1.02 wt.% to <0.13 wt.% (86.24% zinc removal rate) upon microwave processing for 10 min at 800 °C. This level of zinc content is acceptable for the material to be recycled i.e., reused in the blast furnace.