Chemical fractionation of trace elements in coal and coal ash

lThis article examines the chemical fractionation (leaching) of elements fr om the Whitewood Mine subbituminous coals and coal ashes at 120 degrees C, 750 degrees C, and 1000 degrees C. The elements Ba, Zn, and Mn are easily l eached from coal by water, ammonium acetate, and hydrochloride acid. Potass ium is highly extractable by NH4O acetate but very little with HCl. Hydroch loric acid leaches most of Fe, whereas very small quantities of the element are leached by water or NH4O acetate. Low extractability front coal was no ted for Si, Ti, and Co, an indication of their association with detrital mi nerals. Extractability of Na from coal was low which indicates an associati on with minerals rather than being in the form of exchangeable ions. High l eachability for Ca, Sr and to a certain degree Mn, Mg and Na were noted for the 120 degrees C ash samples. Zinc, Ba, S, and P showed a wide variation, reflecting a complex association with carbonate, sulphate, sulphide minera ls, and organic matter. Silica, Al, B, Li, Cu, and Mo were completely insol uble. Calcium, Al, Co, Sr, and Mn were easily extractable from the 750 degr ees C coal ash. Copper in coal ash may be ill the form of oxide, which is m ore leachable. High leachability for Al has an implication of potential ext raction of the element from coal ash in countries that hare no bauxite ore deposits. In the 1000 degrees C ash, S, Zn, and Na were highly leached wher eas Ca, Ba, and Sr were moderately leached Silica, Al, Fe, K, Mg Ti, Mn, an d Cu showed very low extractability.