Alfonso Abella, María PuraPenedo, L.A.Garcia Vallès, MaiteMartínez Manent, SalvadorMartinez, A.Trujillo, J.E.2023-02-232023-02-232022-02-011388-6150https://hdl.handle.net/2445/194014Kaolin is widespread as a result of the alteration in the San José Sn-Ag deposit located in Oruro, Bolivia. This study presents a chemical, mineralogical and thermal characterization of the San José kaolinitic deposit, which is necessary to determine their optimal applications. Mineral phases of these white silty kaolinitic materials were determined by X-ray diffraction (XRD) and are quartz, kaolinite, K-feldspar, muscovite, illite and minor halloysite, dickite, plagioclase, jarosite, rutile, alunite and gypsum. The fraction < 63 µm contains 20-27 mass% of kaolinite. Differential thermal analysis (DTA) shows an endothermic peak at 520 °C associated with the dehydroxylation of kaolinite and an exothermic peak at ~ 980 °C related to the crystallization of mullite. TG curves show a total mass loss up to 1300 °C of about 8 mass%. The dilatometric curves show a shrinkage at about 890 °C produced by the collapse of metakaolinite into a spinel-like structure, and another shrinkage starts at 1010 °C, at the beginning of the sintering, when the spinel-like phase is transformed to mullite and amorphous SiO2. Lightness L* is 80-92, but only the mined materials have b* < 4, suitable for paper filling applications.9 p.application/pdfeng(c) The Author(s), 2022http://creativecommons.org/licenses/by/3.0/es/MineralogiaCaolíBolíviaMineralogyKaolinBoliviainfo:eu-repo/semantics/article7281022023-02-23info:eu-repo/semantics/openAccess