Separation of polythionates and the gold thiosulfate complex in gold thiosulfate leach solutions by ion-interaction chromatography

Abstract

A method for the separation of the polythionates (SxO6(2-), x = 3-5) in gold thiosulfate leach solutions using ion-interaction chromatography with conductivity and ultraviolet (UV) detection is described. Polythionates were eluted within 18 min using an eluent comprising an acetonitrile step gradient at 0.0 min from 15% v/v to 28% v/v, 3 mM TBAOH, and 2.5 mM sodium carbonate, operated using a Dionex NS1-5 micron column with guard. The developed method was capable of separating the gold thiosulfate complex ion in standard solutions, but quantification of this species in realistic leach solutions proved impractical due to a self-elution effect that caused the gold peak to be eluted as a broad band. Detection limits for polythionates using a 10 microL injection volume ranged between 1-6 mg L(-1) (5-23 microM) for conductivity and 0.8-13 mg L(-1) (4-68 microM) for UV detection, based on a signal-to-noise ratio of 2. Calibration was linear over the ranges 5-2000, 10-2000 and 25-2500 mg L(-1) for trithionate, tetrathionate and pentathionate, respectively. The technique was applied successfully to leach liquors containing 0.5 M ammonium thiosulfate, 2 M ammonia, 0.05 M copper sulfate and 20 % m/v gold ore.

Tailored Granular Activated Carbon Treatment of Perchlorate in Drinking Water

“…) appears in hydrothermal waters (Webster, 1987;Barnes, 1979;Veldeman et al, 1991;Xu et al, 1998Xu et al, , 2000 . Also, polythionates are abundant in many different systems such as acid carter lakes (Veldeman et al, 1991) and gold ore leaching solutions (O'Reilly et al, 2002). Schoonen 1989 stated that the concentrations of S 2 O 3 2and other intermediate-valent sulfur species in natural waters should thermodynamically be less that 0.01% of the total dissolved sulfur.…”

Separation of thiosulfate and the polythionates in gold thiosulfate leach solutions by capillary electrophoresis

“…In previous work [15], the gold(I) thiosulfate complex was found to be indeterminable in leach matrices by IC, through what was attributed to a self-elution effect. One of the aims of the present research was, therefore, to investigate whether CE would permit simultaneous determination of this complex and the polythionates.…”

“…, x . 3) increases with chain length [12][13][14], which has resulted in pentathionate (S 5 O 6 27 ) being the highest polythionate detected in thiosulfate leach liquors to date [15].…”

“…In contrast, there is little reference made in the literature to the determination of the gold(I) thiosulfate complex by any chromatographic or electroseparation method. We have recently demonstrated [15] problems preventing the determination of the gold(I) thiosulfate complex by IC in thiosulfate leach solutions, whilst a brief qualitative study using paper chromatography, thin-layer chromatography and paper electrophoresis has also been published [25].…”

“…Fleming et al [17] used IC to measure thiosulfate, trithionate and tetrathionate in leach solutions but did not provide details of the method used. Recently, we have reported the first detailed methodology for IC determination of trithionate, tetrathionate, and pentathionate in undiluted leach solutions [15], but the simultaneous determination of thiosulfate or gold(I) thiosulfate concentration in the leach matrix was not possible.…”