Design and construction of gamma transmission gauge for determination of the ash content in coal

More than two years research work on design of a dual energy γ-ray transmission gauge is reviewed in this paper. The gauge after construction will be to install in a large coal industry named Kerman District Coal Mines (KDCM). KDCM consists of several coal mines, so that, coal transported on a conveyor belt may be a non-homogenious mixture from one or more mines. Therefore, prior to gauge design, primary investigation is done to identify and evaluate the relationship between the mass absorption coefficient (μ-bar) and ash percent of coal for the mixture running on the belt. Results of investigation shows that, coal mixture calibration curve cannot be used accurately for ash estimation in coal of individual mines and, essentially, gauge may work to determine the ash percent with some limitations in this particular region. Therefore, design of gauge was carried out in the laboratory and after setting up, primary experimental calibration curve for the gauge is obtained. The r.m.s. difference between gauge ash and chemical assay is 1.17 wt% ash, for ash in the range of 32-44 (wt%). It is programmed for future to complete and improve the gauge to be able for on-line ash determinations. (author). 5 refs, 7 figs, 2 tabs