Laboratory determination of the ash content of some Australian coals using radioisotope techniques

Two radioisotope techniques suitable for the rapid laboratory determination of the ash content of coal have been tested on unwashed coal samples from four Australian coal seams. In one technique, measurements of backscattered 238Pu L X-rays and iron K X-rays from finely ground coal samples have been combined to determine ash content in unwashed coals to +- 0.5 weight per cent ash for three seams and +- 0.9 weight per cent ash for the fourth. The second technique, which involves measurements of the transmission by the coal of narrow beams of 241Am 60 keV and 133Ba 356 keV ν-rays, requires less sample preparation. The ash was determined to within the range of 0.8 to 2.6 weight per cent for the four seams (unwashed coal). For washed coals, errors are expected to be <+-0.5 weight per cent ash