University Of Cape Town Geology - X-ray Fluorescence

University Of Cape Town Geology – X-ray Fluorescence

Geology is a fascinating combination of scientific research and exploration. Geologists study the composition, development, and dynamics of the Earth to shed light on its mysteries. They have a number of effective tools at their disposal, including X-ray Fluorescence (XRF) analysis, which gives them access to a plethora of knowledge about rocks and minerals. Geologists at the University of Cape Town are pioneers in the application of this method, providing ground-breaking findings and advances in the discipline.

X-ray Fluorescence

The XRF Facility houses a Panalytical Axios XRF spectrometer and is set up to analyze a wide range of major and trace elements in prepared solid materials. Routine analysis of eleven major elements, Fe, Mn, Ti, Ca, K, S, P, Si, Al, Mg, and Na (with Ni and Cr when Ni and Cr concentrations exceed 2000 ppm or 0.2 %) is determined using fused disks prepared with lithium borate flux.

Trace element concentrations are measured on pressed powder briquettes and intensity data are corrected for mass absorption/enhancement and spectral interferences. International rock standards are used for calibration.
South Africa boasts the largest number of X-ray fluorescence instruments in the world. These instruments are used heavily in the characterization of ores and the industrial production of steel and cement, among other applications.

The Department of Geological Sciences at UCT has been at the forefront of X-ray fluorescence technique development since its introduction in the early 1960s. The Department was involved in the XRF analysis of lunar samples returned by the U.S. Apollo missions in the late 1960s and early 1970s, the only laboratory outside of North America and Europe to do so. Emeritus Professors James Willis and David Reid remain involved with the XRF facility at UCT and Prof. Willis directs a short course, sponsored by Panalytical, held every January in the Department.

Equipment
Panalytical Axios wavelength-dispersive XRF spectrometer with sample-changer (56 sample capacity) and a rhodium end-window X-ray tube. A Claisse Fluxer is available to aid in the preparation of fusion disks. A hydraulic cold press and die are used for the preparation of powder briquettes. Sample preparation is done using a custom-built hydraulic splitter, and Sturtevant laboratory jaw-crusher, and sample powdering is done using a Seibtechnik swing mill with carbon steel cassettes of various sizes.

X-ray Diffraction

Geological science commonly analyzes powdered samples for crystalline material qualitative analysis. X-ray diffraction spectra are collected and analyzed using a Phillips PW 3830/40 Generator and a PW 3710 mpd control X-ray diffraction system, both of which are controlled by the Xpert data collector/identify software.

Students are urged to run and analyze their own samples in order to save money because the method is qualitative and the equipment is reasonably simple to use.

The Scientific Officer in charge of the XRD, Mr. Nicholas Laidler, performs external analyses on a first-come, first-served basis for other tertiary institutions and private businesses. The cost of each hour does not include any fees for interpretation or any sample preparation necessary for analysis.

For more information regarding the X-ray Fluorescence Lab, please contact:
Dr. Phil Janney
phil.janney@uct.ac.za
(021) 650-2929
Lab address:
Rm 1.07, Geological Science