Observations on New Approaches for the Determination of Platinum-Group Elements, Gold and Silver in Different Geochemical Samples from Siberia and the Far East |
| |
Authors: | Valentina G Tsimbalist Gennady N Anoshin Valentin N Mitkin Ljudmila I Razvorotneva Nadezhda P Golovanova |
| |
Institution: | United Institute of Geology, Geophysics and Mineralogy SB RAS, Acad. Koptyug pr., 3, Novosibirsk, 630090, Russia;Institute of Inorganic Chemistry SB RAS, Lavrentjeva Av., 3, Novosibirsk, 630090, Russia |
| |
Abstract: | Some recent experiments on the determination of Au and the platinum-group elements (PGE) in geochemical samples are reviewed. Emphasis is given to the determination of ultra-low levels of PGE concentrations in resistant matrices, including chromites, molybdenites and ultrabasic ores. The problems and features of PGE determination in samples of various chemical composition are considered. For each sample type studied, a series of sample preparation techniques are proposed. These techniques included acid digestion, fusion with sodium peroxide, cold sintering with an oxidizing mixture of Na2O2+ Na2CO3 and also oxidizing fluorination with bromine trifluoride. A new approach for preparing geochemical material prior to digestion, based on mechano-chemical activation with simultaneous hyperfine grinding, is proposed and studied. The instrumental determination of PGE contents was carried out directly by AAS from extracted organic phases. It was found that a combination of digestion processes was required to achieve geochemical background levels of Au and PGE concentrations with the following detection limits: Pd, Rh - 1 ng g?1, Pt, Ru - 10 ng g?1, Au - 0.2 ng g?1, Ag - 0.1 ng g?1. The uncertainty in PGE and Au determination in geochemical samples is dependent on metal concentration, and also on their distribution in samples. The total analytical uncertainty of the proposed method is between 15-30%. |
| |
Keywords: | Au platinum-group elements fusion sintering mechano-chemical activation schemes of analysis oxidative fluorination |
|
|