R.H. Filby C.A. Palmer 1983 A procedure has been developed using low temperature ashing, followed by size and sink-float separation of the ash, X-ray diffraction analysis, and instrumental neutron activation analysis to give both qualitative and quantitative information for major, minor and trace minerals and their associated trace elements in coal. application/pdf en DETERMINATION OF MODE OF OCCURRENCE OF TRACE ELEMENTS IN THE UPPER FREEPORT COAL BED USING SIZE AND DENSITY SEPARATION PROCEDURES. text