Chemical analyses in the World Coal Quality Inventory

Coal resource potential of Afghanistan

“…The trace element profiles published by USGS (Tewalt et al 2010) show that Afghan coals generally contain low concentrations of toxic trace elements, though it is unclear if or how these profiles may have been altered by weathering. Several samples, however, contained significant concentrations of toxic heavy metals (lead and arsenic).…”

“…Mostly, proximate/ultimate testing was done and certain physical tests were conducted primarily to determine coking properties. Only the report by Tewalt et al (2010) provides data on forms of sulphur and trace element composition. The coal quality results must be interpreted carefully.…”

“…Only Technoexport geologists collected unequivocally unweathered coal from the drill core. More recently, the USGS has analysed coal samples collected by AGS from several coalfields (Tewalt et al 2010). USGS analyses of samples collected from small mines in the Tala Barfak area are provided in Saifuddin et al (2007).…”

“…Most published quality studies analysed weathered or partially weathered samples. The recent USGS study is an exception (Tewalt et al 2010). • Afghan coal rank varies from lignite to anthracite.…”

Coal-derived rates of atmospheric dust deposition during the Permian

“…This approach assumes that the major lithophile elements (Si, Al, Mg, Fe, Ca, Mn, K, Na, Ti) that constitute the bulk of the inorganic constituents in coal (Bragg et al, 1998;Tewalt et al, 2010) originate predominantly from silicates and oxides in atmospheric dust. This assumption refers to the origin of the elements not to the association of these elements in the coal with mineral matter, organic matter etc.…”