A proposal for bauxite quality control using the combined Rietveld - Le Bail - Internal Standard PXRD method – Part 2: Application to a gibbsitic bauxite from the Paragominas region, northern Brazil. (15th June 2018)

• Record Type: Journal Article
• Authors: Angélica, R.S.; Kahn, H.; Paz, S.P.A.
• Is Part Of: Minerals engineering. Volume 122(2018)
• Page Start: 148
• Page End: 155
• Publication Date: 2018-06-15
• Subjects: Bauxite -- Kaolinite -- X-ray diffraction -- Rietveld method -- Le Bail method -- Internal Standard method; Mines and mineral resources -- Periodicals; Ressources minérales -- Périodiques; Mines and mineral resources; Periodicals; Electronic journals; 622
• DOI: 10.1016/j.mineng.2018.03.039
• Languages: English
• ISSNs: 0892-6875

Abstract

Highlights: A significant innovation in the control of bauxite by PXRD. The combination of Rietveld refinement and the Le Bail Internal Standard method has improved the quantification of phases. The combined Rietveld-Le Bail method decreases the time of computational calculation. The use of an internal standard reduces the error from normalization to 100%. Abstract: In the bauxite industry – exploration, beneficiation and refining – two main chemical parameters are used for quality control: available alumina (AvAl2 O3 ) and reactive silica (RxSiO2 ) content. Both are determined using a wet chemistry procedure that simulates the Bayer process at laboratory scale. For gibbsitic bauxites, the subject of this study, the available alumina is associated with the ore mineral gibbsite, and the reactive silica is associated with the deleterious mineral kaolinite. A significant innovation for this industry would be to characterize bauxite ores using mineralogical parameters, i.e., the wt% of gibbsite and wt% of kaolinite via Powder X-ray Diffraction Analysis (PXRD), which has been employed elsewhere but has been time-consuming and imprecise. A recent proposal for quantification of the main mineral components of bauxite ores for quality control in bauxite mining was developed by Paz et al. (2018) using the combined Rietveld - Le Bail - Internal Standard PXRD method. In this work, the method is tested using a Brazilian bauxite ore from the Paragominas region (Pará state, northern Brazil), and the results are evaluated against those from traditional wet chemistry (AvAl2 O3 and RxSiO2 ). The study concluded that the PXRD method was able to produce results that were directly comparable with those from tradition chemical methods, and with the advantage of requiring only a single analytical instrument.