Beam Interactions with Materials&Atoms Nuclear Instruments and Methods in Physics Research B 130 (1997) 582-586 - ELSEVIER Geochemical analysis of medium sized fly ash particles using the NAC nuclear microprobe P.D.S. Rousseau a, W.J. Przybylowicz b,‘, R. Scheepers ‘, V.M. Prozesky b, C.A. Pineda b, C.L. Churms b, C.G. Ryan ’ a zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Department of Geology. Unicersity of Steltenbosch, PriGate Bug XI, Matielund 7602, South Africa b Nat~[~nai Accelerator Centre, P.O. Box 7.2, Fuure 7331, South Afrisu ’ CSIRO, ~j~~.~~ffn of Exp~[~ruti~)n and ~injtz~, P.O. Box 136. North Ryde, NSW 21 i3, ~a.~ira~~a Abstract Single fly ash particles were analyzed by using a combination of electron microprobe and nuclear microprobe measurements. Trace elements were found to accumulate in these particles by three different mechanisms. Firstly, in some particles trace elements remain associated with unaltered mineral phases. In the second instance, some minerals containing trace elements were dissolved in larger particles, and thirdly, volatile trace elements were found to have reacted with molten fly ash particIes, especially in particles which approach eutectic compositions in the FeO-Al,O,-SiO, and CaO-AI,O,- SiO, ternary systems. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 1. Introduction The properties of fly ash particles are of great environmental concern. Trace element concentrations that are found in some fly ashes have potentially harmful effects to human health, as well as being toxic to other members of the biotic community. The trace eIement distributions in medium sized fly ash particles are important, as these particles make up the major proportion of fly ash particles that are formed during coal combustion El]. In fly ash envi- ronments, it may consequently be expected that this fraction of ash will have the largest effect on bioavaiIability of trace elements over the long term. ’ On leave from the Faculty of Physics and Nuclear Tech- niques. Academy of Mining and Metallurgy, Cmcow, Poland. Particles were selected to investigate correlations of trace element concen~ations with: (1) major element compositions as measured by electron microprobe, (2) optical properties observed under transmitted and reflected light and (3) size measurements of particles obtained with a calibrated graticule. 2. Materials and methods The fly ash particles analyzed were in the size range of 18 pm to 100 &rn from ashes provided by ESCOM, the supplier of most of South Africa’s electricity. The optimum sample preparation method was found to be a modified petrographic mount. A plastic ring was positioned on a piece of adhesive paper, on which fly ash was sprinkled. Loose fly ash 0168-583X/97/$17.00 0 1997 Eisevier Science B.V. All rights resewed PII SO168-583X(97)00255-3 XI. ENVIRONMENTAL SCIENCE