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Analysis of the simultaneous gas-liquid CO2 absorption and liquid-gas NH3 desorption in a hydrometallurgical Waelz oxides purification process

par Wylock, Christophe ;Antunano, Nestor;Arias, Pedro Luis;Haut, Benoît
Référence International journal of chemical reactor engineering, 12, 1
Publication Publié, 2014-10-21

Article révisé par les pairs

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Résumé :

This work deals with the analysis of the mass transfers taking place in a unit operation of a recently developed hydrometallurgical process. This process is a purification treatment of zinc rich electric arc furnace dusts to generate high purity zinc oxide. In this operation, gaseous CO2 generated in a furnace is injected in a reactor containing an aqueous solution of ammonia and ammonium carbonate, which is the leaching solution of these dusts, to precipitate zinc carbonates. During the operation, the gas-liquid CO2 absorption is coupled with a simultaneous liquid-gas NH3 desorption and with several reactions in the leaching solution. This paper aims to propose a mathematical model of the coupling between the mass transports and the reactions and to present a simulation tool for the computation of the CO2 absorption, the NH3 desorption rates and their evolutions with the solution composition.The ability of the presented simulation tool to predict the time evolution of the liquid composition during a gas injection is evaluated by comparing simulation results to experimental results. The pH time evolution is used as the comparison criterion and the experiments are carried out at a bench-scale stirred tank reactor. In addition, simulations results showing the influence of the solution composition in conditions representative of the operating conditions on the CO2 absorption and NH3 desorption rates are presented and discussed.