Ocena liasowych skał ilastych okolic Zawiercia jako nieboksytowych rud glinu w świetle badań derywatograficznycho

Abstract

THE EVALUATION OF LIAS CLAYEY ROCKS AS A NON-BOXITE ALUMINUM ORE BASED ON DERIVATOGRAPIC EXAMINATIONS

Summary

Clayey rocks of various types, some rich in alumina, make up a relatively high percentage or the Lower Jurassic rock complex of the Zawiercie region (Upper Silesia). Some of the rocks also show a high refractoriness.
Samples of the rocks of interest have been examined by means of derivatographic and diffractometer and their chemical composition has been also determined.
On the basis of the derivatograms obtained, among others preliminary evaluations of the alumina content in the clays examined were attempted. It has been found that white sandy clays are built mainly at quartz and kaolinite (fig. 1), whereas the greenish coloured clays contain also illite (fig. 2), siderite, calcite, occasionally chlorite and pyrite. In their mineral composition the dark grey and black clays are similar to the white one, differing in variable organic matter content and minor illite admixture. To compare the Lower Jurassic deposits with the top rocks of the Upper Triassic the latter ones have been, examined by derivatographic methods. Illite, occasionally with minor kaolinite, admixture (fig. 3) has been found to be the predominant mineral.
The alumina content has been determined from the derivatograms with an 80 per cent consistency with the chemical results. An example is given on fig. 4.
It has been found on kaolinite-illite clays that the only rocks of interest are those showing weight losses more than 7 per cent for the characteristic thermal reactions.
The studies carried out have revealed that a part of the Lower Jurassic clayey deposits may be considered as a non-bauxite aluminum ore. Besides, the derivatographic analyses has been found to be a suitable tool for determining the alumina content in the samples and – in some cases – for solving stratigaphic problems.