Geology, Genesis, Mineralogy, Industrial Applications and Resources of Patagonian Kaolins

DONDI, MICHELE; DOMÍNGUEZ, EDUARDO; IGLESIAS, CLAUDIO

Atlanta, Georgia

Congreso; 53rd Annual Meeting of the Clay Minerals Society; 2016

The Clay Minerals Society

Santa Cruz or the Danian-Paleocene Salamanca Formation in Chubut. In order to establish the kaolin?s origin, a considerable number of isotope determinations were performed after the pioneering work of Murray and Jansen (1984). The isotopic evidence indicates that the residual kaolin was formed by weathering in a humid-warm climate in the Jurassic?Cretaceous time interval. In residual deposits, the clay-sized fraction is composed of kaolinite, 7Å halloysite, illite, and quartz with minor amounts of mixed-layered illite-smectite clays or smectites. Kaolinite predominates in the upper and whiter part of the altered layer, and amounts of illite and smectite increase with depth. Kaolinite shows an open texture, with stacks that grew after feldspar. While the ball clays related to the erosion of Bajo Grande are kaolinitic?smectitic, those coming from the Bahia Laura Group are kaolinitic. During paper-kaolin beneficiation, it was evident that the quartz phenocrysts are easily removed by screening, but fine quartz from the groundmass remains in all size fractions. Using the clay fraction and a careful selection of the raw mineral, a filler of high brightness and moderately low abrasion could be produced. For the coating grade, the low recovery and a marginal abrasion preclude an economic factory installation. For ceramic applications, the Patagonian clays naturally have qualities that allow almost the entire range of applications. The ball clay properties are analogous to those of clays used in European porcelain stoneware production (Westerwald, Germany) or to the highly plastic Ukrainian ball clays. The current annual kaolin demand in the country is about 300,000 tons used for flat ceramics, sanitary ware, and glazes. Remaining resources were estimated at 12 MT. The Patagonian region was the southernmost part of a continent where Gondwana paleosurfaces of Late Mesozoic age developed on Jurassic rhyolite volcanic units. This paleosurface is today exposed over tens of thousands of square kilometers in the cratonic units of northern and southern Patagonia and has a strong potential for discovery of new kaolin deposits.