In Poland the name kaolin is referred to soft clay rock (from white to yellowish colour) mainly built of minerals of the kaolinite group. Kaolin originates in result of weathering or hydrothermal decomposition of igneous and metamorphic rocks rich in feldspars. From the origin point of view, differentiation is made between residual kaolin, that is derived from in-situ decomposition of parent rock, and sedimentary kaolin, formed in result of wash down of weathered parent rock and transport and deposition of weathering products in other place.
The name of kaolin raw material is also referred to Upper Cretaceous sandstones with kaolinite cement which occur in the North Sudetic Depression. The re-analysis of Dunino deposit of weathering products of basalts, originally treated as a halloysite deposit, showed that it actually represents kaolinite raw material and should be assigned to this group.
Polish deposits of kaolin raw material originated in result of a regional kaolinization which affected acid igneous and metamorphic rocks throughout vast areas in the foreland of the Sudety Mts, especially the Strzegom-Sobótka and Strzelin granitoid massifs as well as some parts of the Sowie Mts and Izerskie Mts. In the Neogene times the weathering processes gave rise to origin of thick weathering covers and, in this way, kaolin deposits. Two types of kaolin deposits are recognized here: the deposits comprising residual material and those sedimentary in nature. In both cases the deposits appear spatially related to parent rocks and confined to areas of the above mentioned massifs of granites and metamorphic rocks.
High-quality kaolin materials, that are those representing fraction below 15 µm, are used in the manufacture of ceramics, rubber, polymers and fiberglass. In turn, coarser fractions find use in making recently fashionable ceramic wall and floor tiles of "gres porcellanato” type, production of which requires washed kaolin with very low content of coloring oxides such as TiO2 and Fe2O3. Kaolin is also used as raw material for the manufacture of stoneware ceramics, white cement and fire-proof products.
The demand for kaolin raw materials is largely covered by production from domestic deposits so the share of import remains relatively small. Kaolin is also being obtained as by-product in exploitation of glass sands (Biała Góra deposit) and foundry sands (Grudzeń-Las deposit).
Kaolin deposits occurence is presented on the map.
Table 1 shows resources and the state of development and exploration of kaolin raw materials in Poland.
Anticipated economic resources of kaolin amounted to 212.08 million tonnes in 2015 and decreased by 286.65 thousand tonnes in comparison with the previous year due to the exploitation and losses.
Anticipated economic resources of two exploited deposits amounted to 79.41 million tonnes (37% of total anticipated economic resources).
Economic resources decreased due to the exploitation and amounted to 71.36 million tonnes in 2015 which accounts for 90% of anticipated economic resources of exploited deposits.
In 2015, production of kaolin raw materials was bigger than in 2014 and was equal 286.65 thousand tonnes. Exploitation of the Maria III deposit gave 285.30 thousand tonnes and of the Dunino deposit only 1,350 tonnes of raw material (table 2).
Prepared by: Agnieszka Malon