Mineralogical Transformations of Kaolins from Cauquenes (Region of Maule, Chile)

Four kaolin deposits from Cauquenes Province in the VII Region of Maule were studied. Kaolins were moistened until homogeneous agglomerates with 5% of water were obtained. They were pressed (300 kg/cm2, 80 x 40 x 5 mm). The pieces were finally heated. The mineralogical analysis of the fired bodies was carried out by XRD at the following temperatures 835, 980, 1080 and 1160 ºC. Results show the presence of quartz, mullite, spinel, orthoclase, albite, hematite, enstatite, ferrosilite, augite and forsterite for A samples. Quartz, trydimite, anorthite, orthoclase, hematite, corundum, fayalite, ferrosilite and hercynite were present in B samples. Quartz, anorthite, albite, hematite, mullite, microcline, augite and enstatite were present in C kaolin samples. Quartz, mullite, spinel, orthoclase, trydimite, enstatite and olivine were present in D samples. The persistence of illite at least at 835 ºC is shown in all samples. At 1080 ºC mullite is formed in A, C and D series. In these series mullite content is high at 1160 ºC. The samples studied are easily adaptable to ceramic processes (pottery, sanitary, structural ceramic, bricks, etc).