How Bruker XRD and TOPAS help to improve the yield of the Aluminum extraction from bauxite

XRD is an important tool for characterizing the mineralogy of bauxite. Bauxite is a mineral mixture of several Al sources (mostly gibbsite, boehmite) and commercially non-valuable minerals in Aluminum production (quartz, kaolinite, hematite, goethite, rutile, anatase, and other less common minor phases).

Turning red to white

Red bauxite ore is transformed in the Bayer process to white alumina powder. This is the raw material for the electro-metallurgical extraction of Aluminum metal. The yield of the Bayer process is not simply related to the Aluminum grade in Bauxite. A complete mineralogical characterization is needed to predict the processing performance in the refinery, but also fine particle size and crystallinity may hamper the process. X-ray diffraction is sensitive to crystallite size, therefore different size fractions of the same mineral can separately be quantified using TOPAS.

The hidden treasure

Silent,undetected recovery losses are a major concern in modern mineral processing. Some Aluminum may hide in the crystal structure of the iron minerals hematite or goethite by an Al-for-Fe substitution. This part of Aluminum is lost because it is not accessible to the recovery process. Chemical analysis cannot separate the hidden from the accessible Aluminum. TOPAS, however, can directly relate the amount of hidden Aluminum to the peak positions and intensities in the XRD pattern.

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