X-ray spectroscopic method development for quantitative analysis of manganese ore in the Kalahari basin

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Bodiba, A.L
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Vaal University of Technology
Manganese is a crucial element in the manufacturing of steel, which in turn is an essential material in many industries including construction and transportation. Its use in the steel making process results in increased strength and resistance. Manganese samples are analyzed quantitatively by volumetric titration techniques. These wet chemistry methods are simple, accurate, and are sufficiently detailed for ordinary personnel to follow with ease. The research method used included the investigation of using secondary standard created from the current mining activities to match the matrix and mineralogy. The matrix matching standard has shown that the mineralogical effect and matrix effect can be controlled by creating the ore specific program. The matrix and mineralogical effect are the main sources of errors in wavelength dispersive X-ray fluorescence analysis with pressed powder pellets. No fundamental parameters corrections and empirical coefficient correction were made on the press pellets calibration lines. The fusion method was investigated as a universal method that can produce fused beads retaining all the elements of interest. The calibration lines were developed from certified reference material and the results were accurate, substantiating that the fusion method elimination the mineralogical effect, matrix effect and particle size effects. Fusion and press pellet methods were compared with the traditional wet chemical method and the results shows no significant difference between the methods. The new methods were tested against three proficiency schemes for manganese and the results were satisfactory, the z-score was below ±3 for all the elements. The participants used different methods including traditional wet chemical analysis and Inductive coupled plasma (ICP). The press pellets method has shown a good correlation with a fusion method were certified reference material was used for calibrations. The new methods were validated using different statistical methods. All the validation criteria were satisfactory. The calibration range for all the lines were satisfactory. The Limit of quantification (LOQ) values for Mn, Fe, CaO, SiO2, MgO, Al2O3, and P were very low. The new methods for the analysis are therefore sensitive enough to give good results for the expected concentration ranges of each element. The statistical analysis performed between fusion and press pellets methods has proven that there was no significant difference between the methods. The conclusion made after the validation procedures was that the methods Page | iv developed for the analysis of manganese ore was fit for purpose of the analysis of the elements of interest for the Kalahari manganese ore. The study confirmed that the newly developed press pellets methods can be used to analyse routine production samples based on the ore type or the area. Borates fusion method can be used for geological explorations, consignment and trade samples. The proposed XRF methods can replace the traditional wet chemical analysis which is time-consuming, toxic and labourintensive.