Presentation Title

Effects of High pH at Near-ambient Temperature on Decomposition Rate Kinetics of Xanthates in Mining Waters

Format of Presentation

15-minute lecture to be presented the Saturday of the conference

Abstract

Xanthates are a class of compounds used in the mining industry to bind to metals within ore samples as a way to collect the metals for further refinement. How pH conditions for a given solution of xanthates that would be representative of a real sample in an industrial setting (such as a flotation tank or a tailings pond) affect rate kinetics has been studied previously; however, the surface has only just been scratched. Optimizing pH values for the best rate kinetics near ambient temperature for an industrial process remains an unsolved problem. The primary method for analysis was headspace Gas Chromatography-Mass Spectrometry (GC-MS). Previous work by this group looked at two xanthate species; in this study, samples of five different xanthates in high pH solutions were analyzed by testing for the generation of carbon disulphide (CS2) gas at specific time intervals. The five xanthates studied were: potassium amyl xanthate (PAX), potassium butyl xanthate (PBX), potassium ethyl xanthate (PEX), potassium isopropyl xanthate (PIPX), and sodium ethyl xanthate (SEX). Optimal pH level for the rate of xanthate degradation was studied and the rate constants at these pH levels were compared. The column temperature was set to 33 ºC by the GC-MS instrument and pH was controlled by the addition of sodium hydroxide. Stabilization or destabilization of the xanthate decomposition shows a measurable change in the evolution of CS2 gas. This change is calculated and helps to determine the positive or negative effects of a given pH level. By controlling pH as well as temperature, better insight into the nature of these compounds may be elucidated.

Department

Chemistry

Faculty Advisor

Kingsley Donkor

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Effects of High pH at Near-ambient Temperature on Decomposition Rate Kinetics of Xanthates in Mining Waters

Xanthates are a class of compounds used in the mining industry to bind to metals within ore samples as a way to collect the metals for further refinement. How pH conditions for a given solution of xanthates that would be representative of a real sample in an industrial setting (such as a flotation tank or a tailings pond) affect rate kinetics has been studied previously; however, the surface has only just been scratched. Optimizing pH values for the best rate kinetics near ambient temperature for an industrial process remains an unsolved problem. The primary method for analysis was headspace Gas Chromatography-Mass Spectrometry (GC-MS). Previous work by this group looked at two xanthate species; in this study, samples of five different xanthates in high pH solutions were analyzed by testing for the generation of carbon disulphide (CS2) gas at specific time intervals. The five xanthates studied were: potassium amyl xanthate (PAX), potassium butyl xanthate (PBX), potassium ethyl xanthate (PEX), potassium isopropyl xanthate (PIPX), and sodium ethyl xanthate (SEX). Optimal pH level for the rate of xanthate degradation was studied and the rate constants at these pH levels were compared. The column temperature was set to 33 ºC by the GC-MS instrument and pH was controlled by the addition of sodium hydroxide. Stabilization or destabilization of the xanthate decomposition shows a measurable change in the evolution of CS2 gas. This change is calculated and helps to determine the positive or negative effects of a given pH level. By controlling pH as well as temperature, better insight into the nature of these compounds may be elucidated.