Decomposition of Xanthates in Arctic Conditions: Evaluation of Significant Parameters in Process and Environmental Water Samples

Abstract Growing interest in expanding mining operations in the Arctic region has raised concerns about its potential environmental impact. Indeed, xanthates commonly used as flotation collectors of sulfide minerals are also among chemicals of which persistence and toxic effects on the environment can worsen in a sensitive ecosystem such as the Arctic. This article investigated the effects of some physical and chemical variables on the decomposition of xanthates. Temperature revealed to be the key variable given that considered effects have not yet been extensively studied. The decomposition of potassium ethyl xanthate (KEX) was studied first using statistical experimental design to screen the effects of time, temperature, initial KEX concentration, and sulfate concentration. Due to its most significant effect, temperature was studied in more detail in ultrapure water and real samples from a mine site using KEX and sodium isobutyl xanthate (SIBX). The results show that decreasing the temperature increased the half-lives of the studied xanthates. In most cases, the real sample matrix did not significantly affect decomposition rates compared to ultrapure water, except for a sample from a clarified water sump where notable differences were observed: The decomposition of SIBX remained temperature-independent and faster than KEX. The present study indicates that the effect of temperature should be considered when mining activities are done in the Arctic region. This study presents for the first time that temperature significantly decreases the decomposition rate of xanthates in real case study samples.