Kaolinite clays called as refractory clays are an indispensable raw material for the production of aluminosilicate fire resistant materials. They are also used for the production of ceramic tiles and sanitary articles. Such clays originate in the result of wash down of outcropping and near-surface kaolinized rocks and a redeposition of kaolinite, connected with a separation of quartz grains and a marked improvement of fire resistance properties of that raw material.
Kaolinite clays are characterized by a high plasticity and when fired at the temperatures over 1,500oC they form ceramic bodies with a high mechanical strength. A very low content of calcium and magnesium compounds is very advantageous as it results in a rise of melting point of these clays. In turn, the presence of iron compounds results in a yellow to brownish and red color of the refractory clays.
From the dozen or so documented deposit in south-western and central Poland, the only one exploited deposit of refractory clays (Rusko-Jaroszów), is situated in the Lower Silesian region – Dolnośląskie Voivodeship.
Refractory clays deposits are presented on the map.
Table 1 shows the current state of exploration and development of the refractory clay resources.
Anticipated economic resources amounted to 54.19 million tonnes in 2018 and decreased by about 0.07 million tonnes (0.13%) in comparison with 2017 due to the exploitation from Rusko-Jaroszów deposit (0.07 million tonnes).
Anticipated economic resources covered by the detailed exploration (in A+B, C1 categories) were equal 53.51 million tonnes and accounted for 98.75% of total anticipated economic resources.
Economic resources of refractory clays were equal 1.10 million tonnes (2.03% of total anticipated economic resources and 94.02% of anticipated economic resources within exploited deposits). Economic resources decreased by 0.07 million tonnes (5.98%) in comparison with the previous year.
In 2018 the output of refractory clays was equal 70 thousand tonnes and increased by 7 thousand tonnes (11.11%) in comparison with the previous year (Table 2). The exploited raw material may be used without any processing or after firing, as the so-called “fired clays”.
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 refractory clays in Poland in the years 1989-2018.
Prepared by: Marcin Tymiński