Refractory clays

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 1,500^oC 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 single exploited deposits of refractory clays (Rusko-Jaroszów deposit), is situated in the Lower Silesian region. In 2017, there was the concession for the exploitation of the raw material from Chwaliszowice deposit (Lubuskie Voivodeship) extinguished.

Refractory clays deposits are presented on the map.

Table 1 shows the current state of exploration and development of the fireproof clay resources.

Table 1. Refractory clays - million tonnes

Anticipated economic resources amounted to 54.26 million tonnes in 2017 and decreased by 0.05 million tonnes (0.09%) in comparison with 2016 due to the exploitation from Rusko-Jaroszów deposit (0.06 million tonnes) with the resources growth in this deposit equal 0.01 million tonnes.

Anticipated economic resources covered by the detailed exploration (in A+B, C₁ categories) were equal 53.58 million tonnes and accounted for 98.75% of total anticipated economic resources.

Economic resources were equal 1.17 million tonnes (2.16% of total anticipated economic resources and 94.35% of anticipated economic resources within exploited deposits). Economic resources decreased by 0.42 million tonnes (26.42%) in comparison with the previous year.

In 2017 the production of refractory clays was equal 63 thousand tonnes and decreased by 12 thousand tonnes (16.00%) 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 2017 to 0.50 thousand tonnes.

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

Table 2. List of refractory clays deposits - thousand tonnes

Prepared by: Marcin Tymiński