Froth flotation study of SEDEX and VMS Pb-Zn ores under different pulp temperature constraints

Sphalerite flotation represents one of a few sulfide recovery systems that experience significant variations in seasonal performance. The correlation between temperature and plant performance is observable in several zinc mines across the world, where both too high and too low temperatures impact recovery and grade. Here, we study the rougher flotation performance of two lead-zinc ores, of distinct geological settings, under controlled temperature conditions. A central composite design of the experiment approach is used to also investigate the effect of different flotation modifiers, namely lime, copper sulfate pentahydrate, and zinc sulfate heptahydrate. Process performance is evaluated by means of flotation kinetics, bubble size distribution (top), concentrate grade, yield, and water recovery. Results indicate that temperature variations lead to changes in froth stability, where a more stable froth is observed at colder temperatures and leads to higher yield and water recovery – presumably explaining the lower concentrate grades observed industrially.