A new preconcentration technique for the determination of PGMs and gold by fire assay and ICP-OES

Abstract

Accurate determination of platinum group metals (PGMs) and gold (Au) has always proven to be a difficult task, due to their low concentrations in platiniferous ores. The most common preconcentration technique used in analysis of these metals is fire assay with a flux containing nickel or lead. This technique can be improved by using co-collectors. Here we hypothesise that Fe, Co, and Cu can be used as co-collectors to enhance separation and preconcentration of PMGs and gold by fire assay. To test this hypothesis, geological exploration samples from Siyanda Union Mine (Northam, South Africa) were analysed by an inductively coupled plasma-optical emission spectrometer (ICP-OES) for PGMs (Pt, Pd, and Rh) and Au. A control sample (certified reference material AMIS 0426) was also analysed by the same technique. The PGM and Au recoveries from the control sample ranged from 83% to 105% for all three co-collectors, with relative standard deviations less than 10% for the control sample and 7% for the geological samples. The PGM and Au recoveries by Fe and Co co-collectors were modestly higher than that of the Cu-collector. These results indicate that Fe and Co are better co-collectors than Cu, presumably due to the loss of analyte when using Cu. Taken together, Fe and Co co-collectors can be viable alternatives for analysis of PGMs and gold using the fire assay method.

Investigation and mathematical correction of the matrix complexity effect on platinum group metals using inductively coupled plasma optical emission spectrometry determination

“…Therefore, in order to accurately obtain the contents of Pd, Pt, and Rh in Fe-PGMs alloy, NiS assay was used for Rh capture, while Pd and Pt were captured by Pb assay. 12,24,36,40 Finally, the actual contents of Pd, Pt, and Rh were identied as 19 685, 1049, and 667 g t −1 , respectively. In addition, a solution composed of a strong acid and powerful oxidizing agent was used to completely digest Fe-PGMs.…”

“…This is due to the magnitude of the three elements normally present in spent automotive catalysts: Pd > Pt > Rh, 6,35 which also indicated that Pt and Rh were more susceptible to interference from the matrix elements than Pd. [11][12][13] In addition, simulated solutions C and D corresponding to alloy digestion and leaching (50%) were prepared based on the chemical composition of the alloy.…”

“…Accurate determination of PGMs is a very important but challenging task due to the extremely high value of PMGs and the complexity of high matrix element content. [11][12][13] Numerous methods have been adopted for the determination, each of which may contribute signicantly to the PGM analysis, but like all analytical methods, they also suffer from limitations. 14,15 The commonly used methods for PGMs determination include re assay, 16,17 high resolution continuous source graphite furnace atomic absorption spectrometry (HR CS GFAAS), 13 X-ray uorescence spectrometry (XRF and TXRF), 18,19 glow discharge mass spectrometry (GDMS), 20 fusion method, 21 spectrophotometry, 15 electrochemical technique, 22 and ICP analysis.…”

“…However, PGMcontaining materials oen suffer from spectral interferences (e.g., spectral overlap) and non-spectral interferences (matrix effect) in ICP OES determinations due to matrix complexity. 12,13,[28][29][30] Typically, pretreatment, matrix matching, internal standardization, standard addition, and dilution can be used to resolve the interference. However, special attention should be paid to avoiding the introduction of new interferents, potential loss, or contamination of analyte during the analysis.…”

Prediction of Gold associated Mineral worth: An application of mathematically driven artificial neural network technique

“…Systematic alluvial soil sampling techniques were utilized in this work to collect representative soil parts for geochemical investigation. Each gold-bearing sample's compositional constituents were determined using fire assay (FAA) and multi-element analysis (MEA) procedures developed by Masasire et al [27] and Harraz et al [28]. SGS South Africa (PTY) Limited (Randfontein) Laboratory conducted the analysis.…”