Browsing by Author "mwangolombe, Mwambeule Aziz"

Now showing 1 - 1 of 1
  • Thumbnail Image
    Item
    Energy dispersive X-ray pluorescence analysis of tin in geological samples by using x-ray tube with a secondary target
    (University of Dar es Salaam, 1988) mwangolombe, Mwambeule Aziz
    The energy dispersive X-ray Fluorescence (EDXRF) method is applied to analyse and quantify tin in geological samples. Tube excitation with a secondary target is used and quantification of tin in done using the scattered radiation technique characteristic of the secondary target. Brief accounts of different sources of X-ray radiation and various methods of sample preparation are reported. In the case of sample preparation are reported. In the case of sample preparation more emphasis is put on the preparation of geological samples of which this study is based. The different quantitative analytical methods commonly applied in XRF technique are discussed in short. Here, more elaboration is given on the advantages of using the scattered radiation method and hence the use of a secondary target for routine analysis. It is pointed out that this method is fast, cheap and easy for rapid routine analysis of geological samples. Optimization of the excitation system used is described and it is found that the detection limit of tin the different tube current and excitation time falls exponentially when any of the two parameters is varied while keeping the tube voltage constant at 45KV when Lanthanum is used as a secondary target. The average detection limit attained is reported to be about 6.72 ppm. (parts per million). Possible sources of error in peak counts are evaluated and the overall error is found to be not more than 0.625% Calibration for tin analysis is discussed and the different mathematical formulations necessary for tin qualification are established. Absorption and enhancement effects on the tin peak counts are studied and the contribution of light matrix elements on the Compton scattered peak counts are checked. After optimization and calibration, results of tin content for the different rock samples are reported. The method is shown to give satisfactory accuracy of between 2% and 5% for the analysis of standard reference rock samples and between 3% and 8% for the analysis of rocks from Karagwe tin fields and Lupa. Gold Fields. Some of the necessary formulae and graphs are presented in the Appendices.