Platinum group elements

Platinum group elements

The value and assorted uses of gold, platinum and palladium are well known. However, there are a growing number of uses for the rarest of the Platinum Group Elements (PGEs): rhodium (Rh), ruthenium (Ru), iridium (Ir), and osmium (Os) in new technology applications. This, along with their high market price, makes them potentially valuable by-products. Gold, platinum, and palladium may be determined by standard lead oxide collection fire assay and ICP-MS or ICP-AES finish. For the full suite of platinum group elements, nickel sulphide collection fire assay must be used for quantitative results.

Elementos do grupo da platina

PGM by lead collection fire assay

Homogenised and pulverised samples are mixed with flux composed of PbO and SiO2 with variable amounts of borax, soda ash and other reagents. The flux and sample are mixed, then heated at high temperature (>1,000°C) to decompose rock lattices and allow precious metals within the sample to be collected into a lead button. The button is placed in a porous cupel and heated again in an oxidising environment to convert lead to lead oxide that is absorbed into the cupel, leaving the precious metals behind as a doré bead or prill. The gold, platinum and palladium content of the prill is then determined spectroscopically.


Method options for analysis of gold,
platinum & palladium

Code Analyte Range (ppm) Description
Trace Level
PGM-MS23L Pt
Pd
Au		 0.0001-1
0.0002-1
0.001-1		 Super trace Pt, Pd and Au by fire assay and ICP-MS finish.
30g nominal sample weight
 
PGM-MS23
PGM-MS24		 Pt
Pd
Au		 0.0005-1
0.001-1
0.001-1		 Pt, Pd and Au by fire assay and ICP-MS finish. 30g Sample
Pt, Pd and Au by fire assay and ICP-MS finish. 50g Sample
PGM-ICP23
PGM-ICP24		 Pt
Pd
Au		 0.005-10
0.001-10
0.001-10		 Pt, Pd and Au by fire assay and ICP-AES finish. 30g sample
Pt, Pd and Au by fire assay and ICP-AES finish. 50g sample
Ore Grade
PGM-ICP27 Pt
Pd
Au		 0.01-100
0.01-100
0.01-100		 Pt, Pd and Au by fire assay and ICP-AES finish.
30g nominal sample weight
 

PGM by nickel sulphide collection fire assay

A 30g sample is fused with a mixture of soda ash, borax, silica, sulphur and nickel carbonate or nickel oxide at >1,000°C to produce a nickel sulphide button. The button is weighed then milled to a fine powder before dissolution in hydrochloric acid. The platinum group elements and gold are precipitated as tellurides on a cellulose nitrate membrane filter which is then digested in hydrochloric and nitric acids. The final solution is analysed by ICP-MS.

PGM analysis (PGM-MS25NS)

Code Analyte Range (ppm) Description
PGM-MS25NS Pt, Pd 0.002-15 Au, Pt, Pd, Ir, Os, Rh, Ru by nickel sulphide collection fire assay and ICP-MS finish.
30g nominal sample weight.
Au, Rh 0.002-5
Ir 0.001-5
Os 0.002-1
Ru 0.003-5

Rhodium by gold collection fire assay

Rhodium analysis is carried out in a similar manner to PGM by lead collection fire assay, with the additional step of gold inquarting during the fusion process and modified cupellation. Analysis is carried out using ICP-MS instrumentation.

Rhodium analysis (Rh-MS25)

Code Analyte Range (ppm) Description
Rh-MS25 Rh 0.001-1 Rh by fire assay, gold collection and ICP-MS.
30g nominal sample weight

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Nickel Sulphide Fire Assay