DETERMINATION OF ASH CONTENT OF SOME NIGERIAN COALS USING GAMMA TRANSMISSION MEASUREMENTS BY
DETERMINATION OF ASH CONTENT OF SOME NIGERIAN COALS USING GAMMA TRANSMISSION MEASUREMENTS BY
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Date
2007-12
Authors
OMEJE, CORNELIUS UCHENNA
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Abstract
An experimental facility which utilizes gamma transmission technique has been
developed for routine determination of ash content of coal. It consists of 241Am and
137Cs radioisotope sources and NaI(Tl) detector coupled with single channel analyzer,
characterized with relatively high sensitivity and with windows set at appropriate
energy for determination of transmitted γ-counts from the sample. The facility is based
on principles of Absorption and attenuation of low energy -rays which depend on the
mean atomic number of elements and thus can be used to determine the ash content of
coal since the mean atomic number of ash is greater than that of coal matter. The
system was calibrated using simulated standard prepared by doping graphite powder
with different concentrations of incombustible elements in their compound form. The
calibration coefficients determined from measurements of simulated standards
containing different amounts of ash in single and dual energy mode were used for the
determination of ash content of various coal samples obtained from different areas in
Nigeria namely; Okaba, Ogboyoga, Okpara, Ogwashi/Azagba, Owukpa, Lafia-obi and
Inyi. The results compare reasonably well with results from chemical assay of the coal
samples. The predicted ash for single energy also largely agrees with prediction based
on dual energy transmission measurements. The accuracy of ash determinations
however depends to some extent on variation in chemical composition of the ash and
the coal matter. With proper control of sources of experimental error the facility shows
great promise in accurate determination of raw and washed coal samples and
favourably lends itself to adaptation to industrial on-line quality control of coal.
Description
A THESIS SUBMITTED TO THE POSTGRADUATE SCHOOL
IN PARTIAL FULFILLMENT of the REQUIREMENTS FOR THE
AWARD OF DEGREE OF MASTERS IN PHYSICS
(NUCLEAR OPTION)
DEPARTMENT OF PHYSICS
FACULTY OF SCIENCES
AHMADU BELLO UNIVERSITY
ZARIA
NIGERIA
DECEMBER, 2007
Keywords
DETERMINATION, ASH CONTENT, NIGERIAN COALS, GAMMA TRANSMISSION, MEASUREMENTS