| X-ray Fluorescence (XRF) Analysis technique is widely used in areas ofastronomy, archeology, geology, and environmental science, due to its ability ofmulti-elements non-destructive analysis in field. In the application area of geologicalsurvey and mine prospecting, high-sensitive XRF detecting equipment would be useto fast determine the content of multi-element in powder-sample, crude rock and soil.The working period of geological survey and hot-spot checking might be shortening.It's more efficient for mine prospecting, but the cost could be greatly decreased.Aim at the in field application purpose of geology and mine survey, amulti-element high-sensitivity in-situ XRF detecting system was developed andintroduced in this thesis. The protocol instrument is small in size and has the weightof less than 3kg. It can keep running for more than 14h in field. Contents of more than10 elements, such as K, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Sr, can be determinedand reported in field. The detection limit for elements Cu and Zn can reach the levelof 10μg/g. It is a new geophysics instrument for geology and mine survey. And itmight make progress in geology technique of China.As the energy resolution ability for X-ray detector is so important for highsensitive multi-element analysis using Energy-dispersive X-ray Fluorescence(EDXRF) method. For the first time in China, the Si-PIN type thermoelectricallycooled semiconductor detector is adapted in a portable XRF analyzer. The relatedelectronics units for Si-PIN detector and the application software are designed anddeveloped.After the optimization geometry parameters of "source-sample-detector" iscalculated and discussed, an isotope excitation source based "Balance Sides structure"excitation source device is designed. This scheme is found out to be effective forimproving the peak-to-background ratio of XRF. And the detecting sensitivity isimproved as well; Transformerless high voltage bias circuit and temperature feedbackself-adjustable voltage switching regulator for electric-cooler are developed. Thesecircuits can improve the performance of signal-to-noise ratio, reliability, and reducepower consumption of the entire system; A shaping amplifier and a Multi-ChannelAnalyzer, who have well signal-to-noise ratio, high reliability, low power, are alsodesigned; An embedded computer PC/104 is used as the spectra data processingsystem, so as to improved the real-time data processing ability of the portable XRFanalyzer; Pure software based characteristic peak seeking and spectrum stabilizing technique is carried out for XRF analyzing with spectrum drift tracking in field, whereit has the large rang of temperature; An in-situ XRF analysis application software withfriendly interface of Chinese pull-down menu is also developed.The protocol system was used to attend the Geo-PT-International ProficiencyTest of Analytical Geochemistry Laboratories for twice time. It is found out that themulti-element fast analysis result is accurate. Practical test in four copper mineperspective areas in Yunnan province is also done. It shows that the system can meetthe need of multi-element quantitative or semi-quantitative determining for varyobjects, such as powder sample, nature soil and rock sample, sediment sample in fieldin geological survey or mining exploration. Parameters, such as accuracy, precision,detection limit and long-term stability, can reach the requirement stipulated in ChineseSpecification of 1:50000 Geochemical Exploration, DZ/T 0011-91.Based on the achievement of this thesis, nine study papers were published. Threeof them were collected by the Engineering Index (EI). An item of Chinese UtilityModel Patent is also awarded.
|
PDF Full Text Request