Comparison of the reduction behavior through blast furnace sludge of two industrial jarosites

Jarosite is the main by-product of the zinc hydrometallurgical Roast-Leach-Electrowin (RLE) process and contains 35-50 wt% of iron oxide which can be recovered for low-grade iron production. As a follow-up of the positive experience of an industrial jarosite reduction by using blast furnace sludges, this paper proposes the same procedure applied to another industrial jarosite different in S, Pb, Ca and Zn concentration, with the aim of investigating the effect of the origin of the jarosite on the best BFS/jarosite ratio to be implemented in the production of self-reducing briquettes. Thermogravimetric coupled with differential scanning calorimetry analysis has been conducted in argon atmosphere on three BFS/jarosite/quartz mixes to replicate the same C/Fe2O3 ratio (0.131, 0.261, 0.523) and basicity (0.504) used in the previous investigation. Coherently with the results obtained with the first jarosite (J1), also for the new jarosite (J2), the highest iron oxide reduction was obtained for a C/Fe2O3 ratio of 0.261. Consequently, the reducibility of jarosite plus blast furnace sludge is not affected by the chemical composition of the starting jarosite from the point of view of the overall iron reduction yield.