Specific solvent extraction method for the determination of gold in ores and products

Abstract

The development of, and the recipe for, the extraction of gold from ores and products are described.

Samples, suspended in dilute hydrochloric acid, are shaken for up to 3 h with amyl acetate containing a small proportion of bromine. The bromoaurates thus formed are extracted into the organic phase with excellent reproducibility and virtually 100% efficiency. The method appears to be completely specific for gold in that, of 25 elements tested, none was found in the extract in more than trace amounts.

By adjusting the sample masses and volumes of hydrochloric acid and amyl acetate, extracts can be made suitable for the determination of gold by a choice of methods; electrothermal and flame atomic-absorption spectrometry and gravimetry have been applied for sample masses in the range 0.05–400 g.

In both accuracy and precision the results compare favourably with those from standard methods, while comparison between the method of standard additions and the direct use of a calibration line on small samples containing 0.1–0.3 p.p.m. of gold is excellent.