METALLIFEROUS COALS OF AZEYSKOE DEPOSIT OF IRKUTSK COAL BASIN

The relevance of the research is caused by the need to find new sources of valuable elements that determine the development of modern innovative economy. Coals and ashes of coals are considered as their perspective source. The study of geochemical characteristics of coal and modes of occurrence of chemical elements in coals and ashes of the coals is required for estimation of metal content in coal deposits and development of the criteria for detecting metalliferous coals and techniques for extraction of valuable elements. A promising source of valuable elements is Azeyskoe deposit, where the content of a number of valuable elements reaches possible industrially important ore concentrations. The main aim of the research is to study the geochemical characteristics and modes of occurrence of impurity elements in coals, coal ashes and noncoal intercalations in coal seams of Azeyskoe deposit. Objects of the research are coal and coal bearing rocks of Azeyskoe deposit of Irkutsk basin. Methods: instrumental neutron activation analysis, mass spectrometry method with inductively coupled plasma, x-ray phase analysis, scanning electron microscopy with x-ray spectral analysis, ashing with determination of ash content and humidity, extraction of bitumen and humic acids. Results. The authors have determined the enrichment of Azeiskoe deposit coals with a number of rare impurity elements (REE, Sc, Zr, Hf, Ta, Th). Pyroclastic material as a source of rare earth elements, thorium, tantalum, zirconium and hafnium, is very important in this enrichment. It was determined that the coals in oxidation zone are characterized by anomalously high concentrations of rare impurity elements (REE, Sc, Cr, Co, Au), bottom formation zones of coal seams are enriched with heavy rare earth elements, Sc, Co, Sb, Ta, Hf, Ba. Presence of native and intermetallic mineralization in coals is revealed. It is established that in low-sulfur coals (similar to 0,5 %) with a low content of sulfide sulfur native forms of elements-chalcophiles prevail. In total, more than 80 mineral forms of impurity elements, including monazite, bastnezite, zircon, baddeleylte, native and intermetallic compounds, etc., were found out.