Chemistry of Mae Moh lignite ash

The lignite ash collected from Mae Moh Power Plant in Changwat Lampang was analysed by auger electron spectroscopy (AES), X-rays photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS) and X-ray fluorescence (XRF), at the Faculty of Science, University of Western Ontario, Canada. The data show similar results, the major elements being oxygen, calcium, silicon, carbon, aluminium, sulphur, sodium, magnesium, potassium, and iron. Sulphur in form of sulphate is more common in fly ash, associated with sodium and calcium. In the bottom ash, calcium was found as oxide with high content of unburnt carbon. Trace elements have been analysed mainly in SIMS and XRF. The easily volatile components are found in fly ash and nonvolatile components are in the bottom ash. The XRF analysis shows that the elements above 0.1 per cent are Al, Ca, Fe, Mg, K, Na, Si, and Ti. The elements above 100 ppm are As (in fly ash) Ba, Mn, Rb, Sr, and V. The elements found in significant amount but below 100 ppm are Ce, Co, Cr, Cs, Dy, Hf, La, Mo, Ni, U, Sb, Sc, Sm, Ta, Tb, Th and Yb. Most of the toxic elements, such as sulphur and arsenic are associated with fly ash which is dumped into a specially designed ash pond. (author). 3 tabs