Issue 8, 2018

Development of a general acid method for the digestion of gold ore samples together with a comparison of extraction solvents for gold and determination by microwave-induced plasma-atomic emission spectrometry (MIP-AES)

Abstract

In this paper, we explore a variety of aqueous digestion techniques for the determination of gold, in a wide variety of mineral matrices. Acid digestion methods, based upon modified aqua regia in which a larger proportion of nitric acid (5 : 1 HNO3 : HCl) is involved, competes effectively with fire assay to deliver accurate and precise values for gold in a fraction of the time. Using this ratio of acids, simple sand-bath digestions deliver recoveries of 95 to 98% of gold certified reference values, after a digestion time of approximately 35 minutes. Focused infrared digestions, however, take only 15 minutes, and deliver higher recoveries, in the range of 95 to 104% of gold reference values. An ultrasonic digestion with 1,3-dibromo-5,5-dimethylhydantoin acting as a source of bromine, delivered mediocre recoveries of gold. Gold determinations were conducted using inductively coupled plasma-mass spectrometry (ICP-MS). Solvent extraction of gold from digestion solutions effectively preconcentrate gold and significantly reduces interference from major elements, except for those samples containing high concentrations of iron. The use of 2-octanone as extraction solvent exhibited greater sensitivity than the use of the conventional solvent, methyl isobutyl ketone (MIBK). Although 2-ethylhexanol was also effective at extracting gold, its lengthy time for phase separation and memory effects, which increased wash-in and wash-out times, made it a less attractive extraction medium. For solvent extraction methods, microwave induced plasma-atomic emission spectrometry (MP-AES) was used for the determination of gold.

Graphical abstract: Development of a general acid method for the digestion of gold ore samples together with a comparison of extraction solvents for gold and determination by microwave-induced plasma-atomic emission spectrometry (MIP-AES)

Supplementary files

Article information

Article type
Paper
Submitted
01 May 2018
Accepted
29 Jun 2018
First published
29 Jun 2018

J. Anal. At. Spectrom., 2018,33, 1336-1344

Development of a general acid method for the digestion of gold ore samples together with a comparison of extraction solvents for gold and determination by microwave-induced plasma-atomic emission spectrometry (MIP-AES)

W. Helmeczi, E. Helmeczi, L. A. Baker, Y. Wang and I. D. Brindle, J. Anal. At. Spectrom., 2018, 33, 1336 DOI: 10.1039/C8JA00136G

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements