Determination by Ion-Interaction Chromatography of Sulphur Species in Cyanide Solutions: Laboratory Method No. 16/30

摘要

The report describes a method for the determination of thiosulphate, thiocyanate, and tetrathionate in solutions and effluents resulting from the cyanidation of gold. The procedure makes use of reverse-phase ion-interaction chromatography, an acetonitrile mobile phase containing tetrabutyl ammonium hydroxide being used as the pairing reagent. The sulphur species are separated from the copper cyanide complex, which can be determined simultaneously, and their concentrations are measured by means of an ultraviolet (UV) detector at 240 nm. Owing to the degree of separation, interference from other metal cyanide complexes is avoided. The method is accurate and precise, with a relative standard deviation of 0,025 for thiosulphate (3 mg/l), 0,003 for thiocyanate (10 mg/l), and 0,045 for tetrathionate (30 mg/l). Sulphide, although detected by the proposed procedure, cannot be determined quantitatively because it is eluted close to the solvent front, and is therefore subject to interference.