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 kaolinite rocks, are raw materials for the production of whiteware ceramics. From the technology process point of view, 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 ceramic clays are characterized by a worse whiteness degree, but they obtain a high bending strength, a big mechanical and chemical resistance and very low level of water absorption.

Whiteware ceramic clays deposits occur only in Dolnośląskie Voivodeship. There are two types of deposits. First of them are the Upper Cretaceous kaolinite clays forming interlayers in sandstones and are represented by Bolko II and Ocice deposits. The second type are poorly coherent sandstones of kaolinite binder represented by Janina I, Janina-Zachód 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.

The ceramic clays deposits occurrence in Poland is 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 2018 anticipated economic resources of whiteware ceramic clays (faiance and porcelite) amounted to 57.98 million tonnes and decreased by 0.23 million tonnes (0.40%) in comparison with the previous year. Similarly to the previous years, Janina I deposit was the only whiteware ceramic clays deposit exploited in Poland with the output equal 206 thousand tonnes (the sandstones of kaolinite binder). The exploitation dropped by 8 thousand tonnes (3.74%) in comparison with the previous year. Economic resources of the raw material were equal 1.12 million tonnes and decreased by 0.23 million tonnes due to the exploitation and losses. 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 1989-2018.

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 2018 anticipated economic resources of stoneware ceramic clays amounted to 79.04 million tonnes and decreased by 0.19 million tonnes (0.24%). The resources change was the result of a new deposit – Borkowice-Radestów 1 – documentation (+0.08 million tonnes), the exploitation (-0.21 million tonnes) and losses.

Anticipated economic resources within exploited deposits amounted to 8.27 million tonnes which accounts for 10.46% 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 (5.36%) as a result of the exploitation and amounted to 4.41 million tonnes. These resources accounted for 53.33% 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 2018, the output of stoneware ceramic clays came from 4 deposits and was equal 269 thousand tonnes (the growth by 8.03% - 20 thousand tonnes). The output increased by 16 thousand tonnes from Zebrzydowa Zachód deposit (8.12%) and by 2 thousand tonnes from Baranów deposit (10.53%). In the case of Borkowice II deposit there was the output drop recorded – by 1 thousand tonnes (3.03%). In 2018, the exploitation of Rozwady 1 deposit (Mazowieckie Voivodeship) started – the output amounted to 2 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 2018 to 0.51 thousand tonnes.

The figure given below shows changes in domestic resources and production of stoneware ceramic clays in Poland in the years 1989-2018.

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

Prepared by: Marcin Tymiński