In Poland the name kaolin is referred to white to yellowish soft clay rock 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 point of view of origin, 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 the 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 Góry and Izerskie Mts. In the Tertiary 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.
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 213.16 million tonnes in 2011.
Anticipated economic resources of exploited deposits amounted to 80.5 million tonnes (38 % of anticipated economic resources).
In the year 2011, production of kaolin raw materials was higher than in the previous year and was equal 285 thousand tonnes. Exploitation of the Maria III deposit gave 284.5 million tones and of the Dunino deposit only 650 tonnes of that raw material.
High-quality kaolin materials, that is 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) and foundry sands (Grudzeń-Las).
Prepared by: Agnieszka Malon