Ceramic clays

Ceramic clays are generally represented by sedimentary clays of a 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 materials for the 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 or stoneware. Whiteware ceramic clays, attaining almost 50% whiteness when fired at the temperature of 1,300^oC, are used for the production of porcelite and faiance. In turn, stoneware products are characterized by a very low level of water absorption and a high mechanical and chemical resistance.

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 of kaolinite binder represented by Janina-Zachód, Janina I and Nowe Jaroszowice deposits. The usable fraction is separated from these rocks by the 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 the exploration and development of the above discussed deposits.

Table 1. Whiteware ceramic clays - million tonnes

In 2017 anticipated economic resources of whiteware ceramic clays amounted to 58.21 million tonnes and decreased by 0.26 million tonnes (0.44%) in comparison with the previous year. Janina I deposit was the only whiteware ceramic clays deposit exploited in Poland with the output equal 214 thousand tonnes. The exploitation increased by 18 thousand tonnes (9.18%) in comparison with the previous year. Economic resources of the raw material were equal 1.35 million tonnes and increased by 1.03 million tonnes (more than four times) due to the new deposit development plan approved for Janina I deposit. List of deposits is presented in Table 2.

The figure given below shows changes in domestic resources and production of whiteware ceramic clays in Poland in the years 1989-2017.

Table 2. List of whiteware ceramic clays deposits - thousand tonnes

Stoneware ceramic clays occur mainly in the Lower Silesian region and central parts of the country (Dolnośląskie and Świętokrzyskie Voivodeships). Couple of deposits are located in Mazowieckie Voivodeship, while single ones in Łódzkie and Śląskie Voivodeships.

In 2017 anticipated economic resources of stoneware ceramic clays amounted to 79.23 million tonnes and increased by 2.95 million tonnes (3.87%) – due to the new geological documentation with recalculated resources approved for Zebrzydowa Zachód deposit.

Anticipated economic resources within exploited deposits amounted to 8.41 million tonnes (it accounts for 10.61% of total anticipated economic resources). Almost all of these resources were covered by the detailed exploration (A+B, C₁ categories), only in Baranów deposit remain 3 thousand tonnes of resources explored in C₂ category. Economic resources decreased by 0.25 million tonnes (5.09%) as a result of the exploitation and amounted to 4.66 million tonnes. These resources accounted for 55.41% of anticipated economic resources of exploited deposits.

Table 3 shows the current state of exploration and development of these deposits.

Table 3. Stoneware ceramic clays – million tonnes

In 2017, the production of stoneware ceramic clays came from 3 deposits and was equal 249 thousand tonnes (increased by 2.05% - 5 thousand tonnes). The growth was recorded only for Zebrzydowa Zachód deposit (by 18 thousand tonnes – 10.06%), the exploitation from Baranów deposit has not changed and remained at the level of 19 thousand tonnes, whereas the output dropped from Borkowice II deposit (by 13 thousand tonnes – 28.26%). In 2017, there was the concession for the exploitation of the raw materials from Rozwady 1 deposit (Mazowieckie Voivodeship) issued. 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 2017 to 0.50 thousand tonnes.

The figure given below shows changes in domestic resources and production of stoneware ceramic clays in Poland in the years 1989-2017.

Table 4. List of stoneware ceramic clays deposits- thousand tonnes

Prepared by: Marcin Tymiński