Application of Spectrophotometry for Analysis of Arsine Gas in Electrometallurgical Research

Electrowinning is commonly used to remove arsenic, antimony, and bismuth from copper electrorefining circuits and can also be used to recover these metals from purified solutions. However, when an electrolyte contains dissolved arsenic, toxic arsine gas may form on the cathode. For example, in so-called liberator cells, there is a risk of simultaneous arsine gas formation as a side reaction of copper arsenide electrodeposition. This risk is mitigated by having appropriate operating conditions in the electrowinning cell. In order to investigate arsine formation and optimize industrial operations, laboratory-scale experiments are used to study the limits for the formation of arsine gas. This study showed the suitability of pairing the silver diethyldithiocarbamate (AgDDC) spectrophotometric method with electrochemical cells to detect and quantify arsine gas. The aim was to assess the viability of this analysis method on a laboratory scale in the context of electrolytic removal of arsenic from hydrometallurgical process streams. The results suggest that the beginning of arsine gas evolution can be reliably detected using the method studied in the work. Further, it can be used semi-quantitatively when following appropriate procedures. For complete quantitative analysis, further research is required to match the conditions between standard and electrochemical measurements.