Ceramic clays are generally represented by sedimentary clays of marine or lacustrine origin and with minerals of the kaolinite and illite group as the major rock-forming components. The clays, also known as kaoline rocks, are raw material for production of whiteware ceramics such as porcelain and bone china.
From the point of view of process technology, the fired products may be assigned to whiteware and stoneware. Whiteware ceramic clays, attaining almost 50 % whiteness when fired at temperature of 1,300o C, are used to produce porcelite and faiance. In turn, stoneware products are characterized by very low level of water absorption and high mechanical and chemical resistance.
The whiteware ceramic clays occur only in Dolnośląskie Voivodeship. There are two types of deposits. First of them are kaolinite clays in sandstones of the Upper Cretaceous represented by Bolko II, Janina and Ocice deposits. The second are poorly coherent sandstones with cement rich in Kaolinite represented by Janina-Zachód, Janina I and Nowe Jaroszowice deposits. The usable fraction is separated from these rocks by water-washing and the obtained concentrate contains about 30 % of kaolinite clay.
Ceramic clays deposits are presented on the map.
Table 1 shows the current state of exploration and development of the above discussed deposits.
In 2012 anticipated economic resources of whiteware ceramic clays amounted to 59.1 million tonnes and decreased by 0.1 million tonnes.
In 2012, production of white firing ceramic clays was equal 94.34 thousand tonnes and was coming only from the Janina I deposit. List of deposits is presented in table 2.
Stoneware ceramic clays occur mainly in the Lower Silesian region and central parts of the country (Dolnośląskie and Świętokrzyskie Voivodeships).
In 2012 anticipated economic resources of stoneware ceramic clays amounted to 77.08 million tonnes and decreased by 0.04 million tonnes.
In Paszkowice deposit there was underground mining abandoned in 2012 and therefore economic resources decreased by 3.91 million tonnes.
Table 3 shows the current state of exploration and development of these deposits.
In 2012, production of stoneware ceramic clays was equal 177 thousand tonnes (decreased by 18 %) and was coming from two deposits - Zebrzydowa Zachód and Baranów. List of deposits is presented in table 4.
Prepared by: Janina Dyląg