Utilization of blast furnace sludge for the removal of zinc from steelmaking dusts using microwave heating

Mixtures of the dusts and graphite, bulk BFS, >250 µm BFS, and >125-250 µm BFS reductants were heated for 20 min at the microwave power of 1100 W. The results indicated that the zinc removal efficiency depends on the amounts of iron oxide and calcium oxide in the mixtures. The highest zinc removal was observed for mixtures with high calcium oxide and low iron oxide contents. Zinc removal of 92.79-96.06% was achieved for mixtures with >125-250 µm BFS and >250 µm BFS reductants. Therefore, to achieve efficient zinc removal, coarser fractions (>125 µm) of BFS should be utilized. Owing to the excellent microwave absorption and high carbon content of the sludge, BFS can be applied effectively in the processing of steelmaking dusts.