Pre-ignition behavior of lead sulfide in the flame of a flash smelter

At less than 650 °C, the oxidation of lead sulfide (PbS) with oxygen to produce lead sulfate (PbSO4) was found to have a very low activation energy of 10 kJ/mole, a reaction order with respect to oxygen of ∼0.5, and one with respect to sulfur dioxide of 0, though the presence of sulfur dioxide was necessary to sustain the reaction. These kinetic parameters suggest that the rate-limiting step was initially oxygen adsorption, very quickly supplanted by slow intraparticle diffusion of sulfur and lead ions.