Separation of ZnO from the Stainless Steelmaking Dust and Graphite Mixture by Microwave Irradiation

In this study, microwave was used to treat stainless steelmaking dust containing zinc oxide. The effects of heating time, carbon content and zinc oxide content on the removal efficiency of zinc oxide and the reduction efficiency of iron oxide were investigated. Experimental results show that, for the sample with 16% (mass percent, the same below) graphite heated for 10 minutes by 10 kW power microwave, the removal efficiency of zinc oxide is between 80% and 90% and the metallization ratio of iron oxide is between 40% and 60%; Initial zinc oxide content has a slight effect on the removal efficiency of zinc oxide. The results indicate microwave treatment is one of the feasible ways to process metallurgical solid waste containing the metal with low boiling point.

Formation of Cr-Bearing Species in Stainless Steelmaking Dust by Induction Furnace

Stainless steelmaking dust contains significant levels of Cr-bearing phases (typically 0.28~16.5%). In this study, stainless steel was produced in an induction furnace, dust generated during the smelting process is collected in order to classify dust formation mechanisms and effects of operation parameters of smelting process on the formation of Cr(VI) species in the dust. The results showed that approximately 60% of dust generated during stainless steelmaking process by induction furnace is due to entrainment of charge fines, about 30% of dust formed due to metal and slag splashing result in oxygen and argon injection, and only about 10% of dust are formed through vaporization from the melt bath. In addition, the Cr-bearing phases in the dust mainly generate due to slag and metal splash. It can increase Cr(VI) content in the dust by increasing the chromium content in the molten steel, the amount of slag former and temperature of molten. To accelerate the cooling rate during the sampling period will decrease the Cr(VI) content in the dust.