Abstract
In order to determine the exploitation potentiality of a kaolin deposit from Atacama in the north of Chile, two types of kaolin (K-1 and K-2) were characterized by XRD, XRF, SEM/EDXS, size distribution, whiteness and DSC. Kaolinite, quartz, muscovite and albite were recognized as main constituents of the ore deposit, and also a significant amount of impurities that negatively impacts on quality were detected. Results show that the low quality presented by the samples, especially K-2, impedes their industrial use as raw material and further mineral concentration processes are proposed. Finally, the results of thermal analysis confirm a conversion to metakaolin that could be the basis for an alternative processing route.
Highlights
Clays are one of the main components of soils and Earth crust
X-Ray Diffraction (XRD) patterns of K–1 and K–2 are shown in Figure 2, which have been normalized for easier phase identification
In K–1, higher peaks of kaolinite and lower peaks of albite are noted; this could be an indication of a higher proportion kaolinite/albite in K–1, in comparison to K–2
Summary
Clays are one of the main components of soils and Earth crust. They have become one of the most important mineral resource of the human history, and their use goes back to ancient times (Cardarelli, 2008). One of the most important clays is kaolin, a fine grained rock that contains kaolinite (Al2Si2O5(OH)4) as the main constituent. It has low contents of iron and other impurities that can turn color from white to brown, grey, or red, depending on the impurities existing in it. The theoretical composition of kaolinite is 46.54% SiO2; 39.50% Al2O3 and 12.96% H2O, and it has an earthy fracture and pseudo-hexagonal flaky morphology (Murray, 2007)
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