Ceramic clays

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 1,300^o 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.

Table 1. Whiteware ceramic clays - million tonnes

In 2014 anticipated economic resources of whiteware ceramic clays amounted to 58.81 million tonnes and decreased by 0.15 million tonnes in comparison with the previous year mainly due to the exploitation of Janina I deposit. The exploitation increased by 7.3 thousand tonnes (5.4 %) and amounted to 143.32 thousand tonnes. List of deposits is presented in table 2.

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). Single deposits are located in Łódzkie, Mazowieckie and Śląskie Voivodeships.

In 2014 anticipated economic resources of stoneware ceramic clays amounted to 76.74 million tonnes and decreased by 0.61 million tonnes – due to the exploitation and overlooking of the resources within protecting pillars of Wierzbka 1 deposit. Anticipated economic resources within exploited deposits amounted to 5.41 million tonnes (it accounts for 7 % of total anticipated economic resources).

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

Table 3. Stoneware ceramic clays – million tonnes

In 2014, production of stoneware ceramic clays was equal 206 thousand tonnes (increased by 0.5 %) and was coming from three deposits. The significant growth was noted for Baranów deposit (by 7 thousand tonnes) and the exploitation from Borkowice II deposit was started in 2014 (it amounted to 20 thousand tonnes). List of deposits is presented in table 4.

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

Prepared by: Marcin Tymiński