Oxidation behavior of 58 and 72% copper mattes in a simulated flash converting furnace

The oxidation characteristics of solid copper matte particles under simulated Kennecott-Outokumpu Flash Converting conditions are presented. The effects of feed matte grade, matte particle size, oxygen-to-matte mass ratio, oxygen content of the process gas and temperature on the particle oxidation rate, quality of conversion, particle size change and particle morphology were determined. The converting quality was highest (approximately 68) with the 58% copper matte at 1100 °C. At similar conditions, the 72% copper matte was more likely to produce copper oxides and leave unoxidized particles rather than directly produce sulfur dioxide at 1100 °C, resulting in an average converting quality of 55. The quality of conversion was poorest for the 72% matte at 920 °C (approximately 45); the sulfur removal was extremely low even with a relatively high degree of oxidation. Fragmentation of the particles was significant in all cases with the 72% matte. A higher O₂/matte ratio and higher temperature, in general, resulted in increased fragmentation while oxygen enrichment had no significant effect. With the 58% matte, particle size was found to increase for the finest fractions rather than to decrease due to particle expansion.