Krzysztof Galos

Flue-gas desulphurisation products from Polish coal-fired power-plants

Many desulphurisation installations were constructed in the Polish power industry in recent years, so SO2 emissions were reduced by a half to 1.04x106 tonnes in 2000, while SO2 capture increased to 43.7% in 2000. FGD gypsum, obtained by the most important wet-limestone desulphurisation method, is recognised as a substitute for natural gypsum. Its production in Poland started in 1994, and amounted to 1.1x106 tonnes in 2000. It is currently fully used in gypsum binders, plasters and plasterboard manufacture, as well as an additive in the production of Portland cement. Other FGD materials--obtained in dry and semi-dry methods of desulphurisation--have variable phase and chemical compositions, so they do not find industrial applications and are mainly stockpiled in underground mines or open pits. The sulphate-calcium ashes from an AFBC process will probably be used in the cement industry simultaneously as a pozzolanic additive and setting-time regulator, provided that their compositions are constant. Their total supply amounted to ca. 1.5x106 tonnes in 2000, but within 5 years, it should achieve 4.0x106 tonnes.

Polish clayey raw materials for the production of ceramic tiles

Abstract Development of the Polish ceramic industry over the last ten years has resulted in a sharp increase in demand for basic raw materials, especially for ceramic clays - both white- and light-firing as well as red-firing varieties. Polish sources of white-firing clays are rather scarce. Their production is based on Santonian sandy-clayey sediments of the North-Sudetic Trough (Lower Silesia, SW Poland). Light-firing varieties occur mainly in Lower Jurassic sediments on the northern margin of the Holy Cross Mountains (central Poland). Red-firing well-sintering clays of Triassic age are known in the northern margin of the Holy Cross Mountains as well as in the Cracow-Silesian Monocline. The white-firing Santonian clays contain mainly highly-ordered kaolinite (~50%) and quartz (~30%) with minor amounts of illite. Their grain-size median ranges between 1.9 and 2.5 μm. They show moderate plasticity (bending strength after drying at 1.7-1.9 MPa) and weak sinterability (water absorption after firing ~12%), but greater lightness after firing (L parameter ~86%). The lightfiring Jurassic clays are kaolinitic-illitic in character, with a variable content of quartz. Kaolinite is represented by the low-ordered variety. The grain-size median is also variable, ranging between 1.1 and 3.4 μm. They show good plasticity (bending strength after drying 2.6-2.8 MPa), good or very good sinterability (water absorption after firing <6%) but moderate lightness (L ~79%). Triassic red clays are highly polymineralic, with illite, kaolinite, smectite, chlorite and mixedlayered minerals occurring in variable amounts. Their specific features are: large hematite content (5-12%), commonly small CaO content (<0.5 wt.%) and an extremely small organic matter content (≤0.1 wt.%). Their grain-size median usually varies between 2 and 3 μm. Using such clays, sintered ceramics (e.g. stoneware tiles) are obtained after firing in the temperature range 1150-1200°C.