Conditions of the feldspathic raw materials supply from domestic and foreign sources in Poland

Abstract

Feldspars are the most abundant group of rock-forming minerals in the nature. They are components of many rock types, including: pegmatite, granite, syenite (especially nepheline syenite), feldspathic sand and sandstone (arkose). The major commercial value of feldspars rests on their chemical composition, especially on the content of alkalis, i.e. K2O (min. 10%) – preferred in the production of whiteware, or Na2O (min. 7%) – in glass and ceramic tile manufacture. In the majority of applications the lowest possible content of colouring oxides, in particular of Fe2O3 and TiO2, is required. For example, in the production of ceramic wares of high whiteness (porcelain), the content of Fe2O3 and TiO2 cannot exceed 0.15% and 0.05% respectively, while in the case of high quality glass – max. 0.08% Fe2O3 is acceptable. The term ‘feldspar raw material’ or ‘feldspar’ refers to both K and Na feldspar-rich grades as well as to feldspar-quartz ones. In Poland there are only the latter obtained, whereas feldspathic and faldspathoid-rich (nepheline syenite) raw materials are imported.