Elucidation of the Decomposition Kinetics and Thermodynamics of Selected Xanthate Species

Xanthates are a family of eight chemical compounds used in the extraction of sulphide minerals by froth floatation. The rapid degradation of xanthates in aqueous solution presents a major problem for mines that utilize xanthates as their primary mineral extractor. The main by-product of the hydrolysis, carbon disulphide, is common to all xanthates and is quite volatile, making it suitable to analyze in the gaseous phase. Using headspace-gas chromatography-mass spectrometry (HS-GC-MS), a highly sensitive method was developed to detect and quantify the main degradation product (CS2) in xanthate samples. Within this method variables such as temperature, pH, time, and concentration of xanthate were manipulated to catalogue decomposition behaviour of the xanthates. Using this information the nature of the decomposition reaction can be elucidated and rate equations can be developed. Preliminary data suggest that the decomposition follows first order kinetics for all xanthates, and that the rate constant, k, varies between xanthates under equivalent conditions. Additionally, the activation energy of the decomposition of the reaction will be studied under the varying conditions using the developed rate laws and the Arrhenius equation. This work has potential implications in choosing xanthates that are most stable under different conditions, and provide information on how the life cycle of xanthates in the flotation circuit can be used to optimize conditions for flotation and preservation of product in the mining industry