Iły trzeciorzędowe rejonu zielonogórskiego

Abstract

TERTIARY CLAYS IN THE ZIELONA GÓRA REGIONSummaryThe paper deals with the clays found to occur in the Miocene and Pliocene formations of the Zielona Góra Region. Location, character, and way of industrial utilization of the mineral raw material are given, and examinations of the chemical composition and of the physical and ceramic properties of this mineral raw material are presented to Tables l-3. Mineral nature of samples has been determined on the basis of thermal-differential analysis, dilatometry and thermogravimetry. In the region here considered, the clays occur in the form of patches, intercalations and large lenses in the sandy-silty deposits. They are used mainly in red ceramic industry, some varieties being applied in production of low-quality fireclay bricks and of lining plates for heating systems. From the viewpoint of refractory materials interesting are clays that are found in the vicinity of Łęknica (Miocene), Gozdnica, Małomice and Lubsko (Pliocene). The chemical composition of the clays here considered is characterized by a high content of SiO2, and a lower content of Al2O3 as compared with the type refractory clays. This gives to the mineral raw material and acid character. According to the criteria applied in the industry of refractory materials, the normal refractoriness of the clay samples from Łęknica, Małomice and Lubsko (167-171 sP) corresponds to that of the average species. The clays from Gazdnica belong to low-refractory type (163-165 sP). Ceramic research illustrates that the clays in study are medium-plastic. They frit at a temperature of 1100-l400°C, optimum ceramic properties being at a temperature from 1200 to 1300°C. As concerns the mineral composition of the clays, beside the predominating kaolinite also admixture of illite and montmorillonite occurs. This may be seen from the interpretation of differential thermograms (Fig. 2), and dilatometric curves (Fig. 3). Table 3 gives the results of measurements of the changes of mass during the heating of samples. Clays with considerable admixture of illite and montmorillonite show the greatest loss of mass at a temperature of 100-200°C. The research, made have led to a conclusion that the refractory clay varieties occur mainly in the Miocene formations. They are found also in the lower horizon of the Poznań clay series (Pliocene), but due to their considerable lithological and technological variations, some difficulties exist in the determinations of larger exploitation complexes of levels. As concerns their mineral composition, the Pliocene clays differ from the Miocene ones in having greater amounts of illite and montmorillonite. Both minerals are predominant components among the non-refractory varieties. In refractory clays, in turn, kaolinite is the main mineral. All the clays contain a lesser or greater admixture of organic substance and of iron hydroxides. Due to their acid character, the refractory clays found to occur in the Zielona Góra Region may be used in production of qartz-chamotte materials.