Cluster Analysis from X-ray Diffraction data: A practical tool for mineralogical classification of bauxites and related products from the Bayer digestion

The main objective of this work is to use the Cluster Analysis statistical tool from X-ray diffraction data to classify different bauxite types and their related products from the Bayer Digestion. 172 samples were used (168 bauxites and 4 samples from kaolinite-rich fines from bauxite washing. All samples come from the Miltonia 3 mine, Paragominas-PA. The results show that gibbsite, kaolinite, Al-goethite, hematite and anatase are the main minerals present in all samples. In the industry, quality control is carried out mainly using wet chemical methods (available alumina and reactive silica, an indirect measure of the amount of gibbsite and kaolinite, respectively). Meanwhile, by using Cluster Analysis of XRD data, an additional parameter can be evaluated, the crystallinity of the minerals from the samples. For the residual solids of the digestion it was also possible to observe the following inert phases: Al-goethite, hematite and anatase; besides the presence or absence of sodalite, kaolinite and gibbsite. It was also possible to observe and differentiate lithologies with kaolinites more reactive in the Bayer digestion.