Adsorption of sulfur on Lanxess Lewatit? AF 5 resin during the acidic albion leaching process for chalcopyrite

Elemental sulfur is one of the major byproducts of the acidic Albion leaching process for chal-copyrite. It is a challenging component in the leach solution as it impedes gold recovery from the residue. Lanxess Lewatit (R) AF 5 (AF 5) is a microporous carbon-based resin, which is being investigated for the removal of elemental sulfur during this leaching process. In the current research, 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. One hundred percent of the elemental sulfur could be adsorbed by the AF 5 resin from the acidic Albion leaching process for chalco-pyrite. Adsorption isotherms at various temperatures were determined using the Langmuir and Freundlich models. The maximum sorption capacity of AF 5 at 95 degrees 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 was best suited to describe 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 as follows: Delta Gads o = -1.9 kJ/mol, Delta Hads o = -9.1 kJ/mol, and Delta Sadso = -0.1 kJ/(mol K). The negative free energy and enthalpy changes demonstrated that the adsorption of elemental sulfur was both spontaneous and exothermic over the temperature range studied.

Automated summary

In this study, a series of leaching experiments were conducted to investigate the removal of elemental sulfur using Lanxess Lewatit (R) AF 5 resin. It was found that 100% of the sulfur could be adsorbed by the AF 5 resin from the acidic Albion leaching process. Adsorption isotherms were determined using Langmuir and Freundlich models, and the maximum sorption capacity of AF 5 at 95 degrees C was 488 mg/g. The kinetics of sulfur adsorption were best described by the pseudo-first order model, and the spontaneous and exothermic nature of the adsorption process was confirmed by the negative free energy and enthalpy changes.