Feasibility studies of low energy γ-ray techniques for on-line determination of ash content of coal on conveyors

Abstract

Low energy γ-ray transmission measurements on suites of 100 kg samples from each of four different coal areas of Australia gave errors in ash determination of 0.99, 1.20, 1.59 and 2.24 wt% (1α), respectively, for mean ash contents of 20.0, 27.1, 24.5 and 17.1 wt% ash. Calculations show that the main errors in ash determination are caused by variations of Fe 2O 3 in the ash, and the wt% ash error is proportional to the ash concentration. An error of about 0.5 wt% is predicted for washery product with ash content of 8 wt%. The most promising applications of low energy γ-ray techniques are for direct on-line determination of ash in washed coal, and for raw coal where accuracy required is not high or iron variations in the ash are small.