Development of ceramic porcelain stoneware pastes by the revalorization of Colombian clays subjected to bleaching process

Abstract

The objective of this work has been the development of porcelain stoneware pastes by using clays from Colombia, obtaining a product exhibiting at least the same technical characteristics that the conventional one. For this purpose, different raw materials, including kaolinitic clays, feldspars, and pozzolans, have been studied from the central area of the country, specifically from the regions of Cundinamarca and Boyacá. Some of these raw materials, having contents of iron oxide above 1%, were subjected to both physical and chemical benefit processes in order to reduce the amount of this coloring oxide. The heap leaching method with oxalic acid at environmental temperature has obtained the best results, with a reduction in iron oxide content of 60 wt%. As for the need to achieve a high degree of sintering, in this work different fluxes such as natural pozzolan, nepheline-syenite and recycled glass have been used, showing that the introduction of these materials into the composition can provide the complementary fluxing and can also reduce the sintering temperature.