Mineral modes of rare elements in coals and ashes of coals of Azey deposit in Irkutsk coal basin

Abstract

Relevance of the work is caused by the necessity to obtain new data on the rare metal potential of Azey coal deposit, to develop the techniques for studying the modes of occurrence elements in coals and wastes of coal combustion, and the possibility of further development of methods to extract rare elements from coals and wastes of coal combustion. The main aim of the research is to study the mineral modes of occurrence of rare elements in coals, coal ashes and clay interlayers in coal seams of Azey deposit; to demonstrate the content of the variety of micro-minerals enriched with rare elements in the coals. The methods used in the study: ashing samples at 815±10 °C determining ash content according to the GOST 11022-95; scanning electron microscopy using Hitachi S-3400N microscope with energy dispersive spectrometer Bruker XFlash 4010 for semi-quantitative X-ray analysis. The results of the research indicate the wealth of rare-metal mineralogy of Azey coal deposit. The detailed study of coals of the seam II revealed both minerals which are widespread for coals (zircon, monazite, etc.) and those which are completely unique, such as Si-Al-Na-Ca-Zr-Sc-Ti-V-Fe-O (Panguite?). The authors have determined the specific feature of the rare-earth mineralization of Azey coal deposits. The fluoro-carbonates (bastnesite?) with authigenic origin are the predominant form of mineral light rare earth elements. In contact with tonstein the significant amount of rare earth phosphates and crystals of baddeleyite was found. Uranium oxides and silicates were revealed both in coal and in tonstein. In all uranium minerals the authors identified zirconium impurity