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 technology process point of view of, the fired products may be assigned to whiteware and stoneware. Whiteware ceramic clays, attaining almost 50% whiteness when fired at temperature of 1,300oC, 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 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 2015 anticipated economic resources of whiteware ceramic clays amounted to 58.53 million tonnes and decreased by 0.27 million tonnes in comparison with the previous year. It was due to the crossing Janina deposit out from “The balance…” (0.15 million tonnes) and due to the exploitation and the change of the mining area border of Janina I deposit (0.12 million tonnes). Janina I was the only whiteware ceramic clays deposit exploited in Poland with the output equal 112 thousand tonnes. The exploitation decreased by 31 thousand tonnes (21.68%). 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). Single deposits are located in Łódzkie, Mazowieckie and Śląskie Voivodeships.
In 2015 anticipated economic resources of stoneware ceramic clays amounted to 76.40 million tonnes and decreased by 0.34 million tonnes – due to the crossing five deposits out from “The balance…”: Barbara Sadlno (kop.), Gierałtów, Kleszczowa, Nowogrodziec II and Zebrzydowa (total resources equal 0.64 million tonnes); the exploitation and losses in exploited deposits (0.21 million tonnes). The resources growth (by 0.51 million tonnes) in Borkowice II deposit was caused by the approving of the new documentation with recalculated resources.
Anticipated economic resources within exploited deposits amounted to 5.72 million tonnes (it accounts for 7.5% of total anticipated economic resources). Almost all of these resources were covered by the detailed exploration (A, B, C1 categories), only in Baranów deposit remains 3 thousand tonnes of deposits explored in C2 category. Economic resources amounted to 4.48 million tonnes and accounted for 78.3% of anticipated economic resources of exploited deposits.
Table 3 shows the current state of exploration and development of these deposits.
In 2015, production of stoneware ceramic clays came from three deposits and was equal 231 thousand tonnes (increased by 12.1% - 25 thousand tonnes). The significant growth was recorded for Zebrzydowa Zachód deposit (by 14 thousand tonnes) and the exploitation from Borkowice II deposit has not changed in comparison with the previous year (it amounted to 20 thousand tonnes). The output dropped in the Baranów deposit (by 5 thousand tonnes). List of deposits is presented in table 4.
PGE Górnictwo i Energetyka Konwencjonalna SA (PGE GiEK SA) informed that the exploitation of refractory and ceramic clays from non-documented deposits (so-called exploitation points) in the KWB Turów Mining Plant amounted in 2015 to 4.08 thousand tonnes.
Prepared by: Marcin Tymiński