Determination of fluorine in zinc ores using an isotope neutron source based automated neutron activation analysis system

A method has been developed for the routine determination of fluorine in zinc sulfide ores by activation with fast neutrons from a 6.6 Ci 227Ac-Be isotope source and by counting of the 4.5 to 7 MeV gamma-rays of the product nuclide 16N. The samples and standards consist of pellets pressed from a mixture of powdered material with wax or graphite. Samples and standards alternate in a sequence of 20 seconds irradiation, 4 seconds decay and 20 seconds counting. This analysis sequence, including the computation of the analysis results from the counting data is automated by means of a LSI-11 Microprocessor with 12Kx16 bit memory. The zinc ores, containing 0.3 to 0.7% fluorine have been analysed with a precision ranging from 1.56 to 1.33% relative. As a test for the reliability of the method, three standard reference materials were analysed in the same way as the zinc ore samples. (author)