Noble and Rare Metals in Some Coal Deposits of Kazakhstan
The concentrations of the impurities in brown coals some of Kazakhstan deposits - «Kulan», «Shoptikol’», «Oi Karogai», «Sarykum» - were determined. Surface inclusions in coals were studied using optical USB microscopes. The composition of inclusions and total composition of coals were analyzed by both X-ray spectrometry with energy dispersion and atomic emission spectrometry using «Grand-Potok» complex with sample introduction by the spill-injection method into an arc discharge and recording spectra with an analyzer MAÉS. Gold was determined on a «Grand-Potok» complex using scintillation method. The coals of «Oi Karogai», «Sarykum», and «Kulan» deposits exhibited inclusions of pyrite in crystalline form. It was shown, that both gold and silver are present only in the coals of the «Shoptikol’» deposit in the form of flat round inclusions. Inclusions formed particles of gold-silver alloy upon melting according to data of scintillation analysis. The average concentrations of gold and silver in the coal samples of the «Shoptikol’» deposit are 0.007 and 0.03 ppm, respectively. It is shown that scintillation determination of precious metals in brown coals of Kazakhstan on a «Grand-Potok» complex with MAÉS analyzer is more rapid compared to the methods of inductively-coupled plasma-mass spectrometry (ICP-MS), atomic emission spectrometry (AES) and atomic absorption spectrometry (AAS) at comparable detection limits.