Z. Šír

Determination of gold in leach liquors by anodic stripping voltammetry in non-aqueous medium

Abstract The anodic stripping voltammetry of gold in butyl acetate/methanol (2 + 1) mixture is reported. The tetrachloroaurate(III) complex is extracted into butyl acetate, lithium perchlorate in methanol is added, and gold is deposited on a glassy carbon rotating disk cathode at −0.6 V vs. SCE. The deposited gold is stripped in the same medium at a scan rate of 50 mV s −1 . The method is suitable for the determination of gold (0.1–1 mg l −1 ) in chloride leach liquors.

Determination of gold by atomic absorption spectrometry after extraction into the non-desulphurized fraction of crude oil distillate

Abstract The extraction of gold from aqueous chloride solutions into non-desulphurized fractions of crude oil distillates, especially paraffin oil, is described. The fraction boiling at 150–220°C exhibited optimum properties. The extraction is tested for solutions containing chlorides, dissolved chlorine and 0.1–3 M hydrochloric acid. Nitric acid should be absent. The distribution coefficient of gold varies from 400 to 900. Extracts containing ⩽ 0.3 g l −1 gold are stable for at least 12 months. The organic extract is sprayed into a lean acetylene/air flame with measurement at 242.8 nm (background correction). The calibration graph has linear portions over the ranges 0–2.5 and 2.5–16 mg l −1 . The limit of detection is 0.03 mg l −1 gold in the extract (0.001 mg l −1 in the aqueous phase). The minimum measurable concentration for gold in auriferous rocks and ores is 0.018 g per ton with 25-g samples.