Direct reduction of lead sulfide with carbon and lime; Effect of catalysts:Part ii. analytical model

The experimental data presented in the Part I of this series are interpreted by means of an analytical model. The model is derived on the premise that the Boudouard reaction controls the overall rate of the reduction process in the PbS:4CaO:4C mixtures. The presence of the catalyst is considered to enhance the density of reaction sites on the carbon surface. For the uncatalyzed reduction under nitrogen, the model gives logI ₁ ^u = 4.988 (± 0.408) - 10216 (± 477)T⁻¹. A similar analysis conducted with the catalyzed reduction experiments provided the following relation: logI ₁ ^c = 4.032 (± 0.280) - 7976 (± 329)T ^-1. It is clear that the addition of the (K, Li, Na)₂CO₃ catalyst, in the amount of 2.5 wt pet, causes definite enhancement in the value of the intrinsic rate constant /,. The latter is expressed in mole · (g · C)⁻¹ · atm⁻¹ · s⁻¹. The magnitude of rate enhancement ranges from 13.6 at 800 ‡C to 6.4 at 1000 ‡C.