Reactor models for a series of continuous stirred tank reactors with a gas-liquid-solid leaching system: Part III. Model application

Abstract

A mathematical model developed to describe the steady-state performance of a three-phase leaching reactor is applied to the analysis and simulation of an industrial process: the high-temperature (180 °C to 200 °C) aqueous pressure oxidation (O2-H2SO4) of refractory pyrite-arsenopyrite (FeS2-FeAsS) gold concentrates. The simulation work reported here centers on the analysis of the autothermal operation of a continuous multistage horizontal autoclave. The focus is on the performance of the first autoclave compartment, since its autothermal “initialization” determines the rate of the whole process. The analysis of the whole autoclave is subsequently done on a stage-by-stage basis. The model considers both possible reaction control regimes, that is, reactor operation limited by the rate of the particle dissolution reaction (surface reaction control)or limited by the rate of O2 transfer at the g-1 interface (gas-transfer control). The decision whether the reactor operates under surface reaction control or gas transfer control is based on whether the gas-transfer capacity of the reactor can or cannot satisfy the oxygen demands of the leaching reactions. With the aid of the model, the effects of feed rate, feed preheating, cooling with water injection, slurry recycling, and autoclave configuration are critically evaluated from the standpoint of optimum autoclave performance.