Improving the Efficiency of the Albion Leach Process: Elemental Sulfur Removal from the Residue Using Lanxess Lewatit® AF 5
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Authors
Marzoughi, Omid
Date
Type
thesis
Language
eng
Keyword
Albion Leaching , Chalcopyrite , Lanxess Lewatit® AF 5 , Regeneration , Mechanism
Alternative Title
Abstract
Elemental sulfur is a key component in the acidic Albion chalcopyrite atmospheric leaching process and is a challenging issue in the residue. The removal of this elemental sulfur from the final leach residue produced during the atmospheric oxidative leaching of chalcopyrite concentrates is both a technical and an economic challenge. Lanxess Lewatit® AF 5 is a microporous carbon-based catalyst and is a promising candidate material that can collect elemental sulfur during the leaching process. This study focuses on removing the elemental sulfur during the acidic Albion leaching process using this new catalyst and regenerating the catalyst via different methods.
Toluene and tetrachloroethylene were studied as potential organic solvents for the removal of the sulfur from the sulfur loaded AF 5. The effects of temperature, time and AF 5 to solvent ratio on sulfur removal from the sulfur loaded AF 5 were examined. The optimum desulfurization conditions were 100 °C for toluene and 110 °C for tetrachloroethylene for an AF 5 to solvent ratio of 1:50 and a processing time of 120 min. Furthermore, the optimum conditions for the removal of sulfur from the catalyst using a high temperature process in a tube furnace were investigated. The results indicated that the maximum desulfurization of 90.1% was achieved at 550 °C after 10 min.
The mechanisms of elemental sulfur adsorption on AF 5 were examined in the leaching test. A series of leaching experiments were performed as a function of temperature, agitation speed and concentrate to AF 5 ratio. Using these results, the adsorption isotherms, the kinetics and the thermodynamics of sulfur removal were studied. Adsorption isotherms at various temperatures were determined using the Langmuir and Freundlich models. The maximum sorption capacity of AF 5 at 95 °C was 488 mg/g. The kinetic data were fitted to pseudo-first order (PFO) and pseudo-second order (PSO) models and it was shown that the PFO model gave the best fit to the results. The rapid kinetics of sulfur adsorption were attributed to the open pore structure of the AF 5. The Gibbs free energy, enthalpy and entropy of sulfur adsorption by AF 5 were determined.
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ProQuest PhD and Master's Theses International Dissemination Agreement
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Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.