Process optimization of preparing glass-ceramic from secondary slag of zinc extraction

As a common method of dealing with dust with zinc in steel and iron plants, the Waelz process can recover zinc and other recycled materials from the dust from iron and steel industry, and produce a large amount of high temperature (1 200~1 300 ℃) secondary slag. In this paper, the secondary slag resulting from the extraction of zinc, as the research object, is treated by four different processes: direct smelting, smelting reduction and iron removal, melting by oxygen-blowing at high temperature(1 500 ℃) and melting by oxygen-blowing at low temperature (1 200 ℃), respectively, to prepare glass-ceramic by one-step process. These results showed that the glass-ceramics treated by the smelting and reduction process had the highest flexural strength(123.77 MPa) and water absorption (0.65%). Low temperature oxygen-blowing melting process cost the least melting energy and produced glass-ceramic with relatively high rupture strength (64.48 MPa) and water absorption (0.48%). Further analysis of the heat balance indicated that the heat released was enough to melt secondary slag on condition that oxygen was blown into the slag at temperatures not lower than 1 162 ℃ and the heat utilization efficiency was 50%.