Determination of aluminium in bulk coal samples by neutron activation analysis

The determination of Al₂O₃, in bulk coal samples to an accuracy of about 0.2% Al₂O₃ has been achieved by means of a thermal-neutron activation technique based on the reaction ²⁷Al(n,γ)²⁸Al. In the analysed samples, which had widely different compositions, the Al₂O₃ concentrations ranged from 1 to 11% and the ash contents from 7 to 40%. Al₂O₃ concentrations measured by x-ray fluorescence showed a linear relationship with both the 1.78-MeV γ-ray count following the decay of ²⁸Al and the thermal-neutron count near the samples during irradiation. The linear relationship, which was obtained by regression analysis of the experimental data, determined the Al₂O₃concentrations with a standard deviation of 0.24% Al₂O₃. The particle sizes in the samples ranged from —0.5 to —40 mm, the moisture contents ranged from 1 to 6%, and the sample weights ranged from 8 to 11 kg. However, inclusion of these parameters in the regression analysis did not significantly improve the results for Al₂O₃.