Concentration Levels of Industrially Valuable Trace Elements in Coals

The concentration levels of valuable (rare, rare-earth, noble, nonferrous, radioactive, etc.) metals in coals were studied for the preliminary assessment of their possible industrial importance. With consideration for the similarity of the composition of the mineral matrix of coal or coal ash to the trace-element composition of the industrial types of ores (silicates, sulfides, and placers), the use of the minimum industrial concentrations of elements was proposed for the above assessment of the trace elements of coal.