Ignition temperature was measured for five kinds of copper concentrates in air and pure oxygen gas flows. In the air oxidation, no significant difference was observed in the ignition temperatures for the concentrates. In contrast, the ignition temperature in oxygen flow depended on the kinds of major minerals contained in respective concentrate. The ignition temperature increases when the concentrate contains higher quantity of Cu5FeS4 or FeS that have lower dissociation pressure than CuFeS2. However, the concentrates mainly composed of Cu9S5, that has a lower pressure of sulfur than CuFeS2, or FeS2 exhibited the lowest ignition temperature. This suggests that Cu9S5 in the concentrate may have a composition of high sulfur pressure, because the dissociation pressure of Cu9S5 changes significantly with minor variation of its composition.
