par Wylock, Christophe ;Antunano, Nestor;Arias, Pedro Luis;Haut, Benoît
Référence 9th World Congress of Chemical Engineering(18-23 /08/2013: Seoul (Republic of South Korea)), Proceedings of the 9th World Congress of Chemical Engineering
Publication Publié, 2013-08-18
Abstract de conférence
Résumé : The steelmaking industry that uses electric arc furnaces (EAF) generates as its main residue EAF dust, which must be treated to recycle Zn, Pb and other metals to prevent environmental impacts. Waelz process is the most common technology for this purpose, generating concentrates of Zn and Pb oxides (called Waelz oxides). One of their many applications is the Zn production in Imperial Smelting furnaces. This work deals with the development of a regeneration process of leaching liquors used in a new hydrometallurgical process for the Waelz Oxides purification treatment producing high purity zinc oxide. In this process, Waelz oxides are dissolved in leaching solutions consisting in ammonium carbonate and ammonia aqueous solutions. After oxidation and cementation stages to remove Fe, Cu and other impurities, a zinc carbonate precipitate is recovered by gas-liquid absorption of CO2 coming from the Waelz furnace flue gas or the zinc carbonate calcination. This step is accompanied by NH3 desorption, which must therefore be regenerated. CO2 capture and NH3 recuperation lead to significant environmental and economic improvements but these processes are complex physicochemical stages demanding careful controls of temperature and pH. A key step to design such regeneration process is the modelling of the gas-liquid CO2 and NH3 exchanges, which are coupled with several reactions in the solution. A mathematical model, taking into account mass transports and the whole reaction system was therefore developed. CO2 absorption experiments were also carried out in a bench-scale stirred tank reactor and the experimental results enabled model improvement and validation.

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