Estimating activation energy from a sulfide self-heating test

Using a custom-designed self-heating apparatus and procedure, activation energy (Ea) was determined for four sulfide-bearing materials: two nickel concentrates, a copper concentrate and a sphalerite/pyrite mixture. The Ea ranged from 22–29 kJ mol−1, implying a common reaction. Comparing to literature, the Ea values correspond to partial oxidation of hydrogen sulfide, supporting the contention that H2S may be an intermediate product in the self-heating of sulfide minerals.