Clay raw materials for cement production
Clay raw materials are used to provide alumina and silica to the charge for the cement kiln and thus counterbalance too high content of CaCO3 in limestones and marls. The optimum content of CaCO3 in the kiln charge is 75-80 %. When CaCO3 exceeds these values, clays are added to reduce its content at the advantage of SiO2, Al2O3 and Fe2O3.
Clay raw materials are qualified to the law raw materials group. According to the classification used in cement industry: law raw materials contain <42 % CaO (75 % CaCO3), normal raw materials contain 42-45 % CaO (75-80 % CaCO3) and high raw materials contain >45 % CaO (80 % CaCO3).
The advancements in development and current exploitation of these raw materials are relatively low. This is due to two factors: (1) attempts to achieve the optimum composition of mined major raw material (in this case – limestones and marls) and, in this way, to diminish the problems with its correction, usually made by the operators at the development stage, that is at the stage of works performed to open a mineral deposit for exploitation, and (2) replacement of natural clay raw materials with mineral waste raw materials such as ash from heat and power plants, blast furnace slag and similar ones.
Lithologically the explored deposits of raw materials for the cement industry represent loams, clays, clay siderites, loesses and silts.
Anticipated economic resources of clay raw material deposits for the cement industry decreased in 2012 by 7.87 million tonnes (in comparison with 2011) and were reported to be equal 275.85 million tonnes.
Deposits of clay raw materials for cement production (together with building ceramics raw materials) are presented on the map.
There was not any new deposit documented in 2012.
Exploitation is carrying on only in Lubelskie Voivodeship area. In 2012 output amounted to 88.74 thousand tonnes and decreased by 25.9 % in comparison with 2011.
The Kujawy cement plant also uses sands from the Barcin-Piechcin-Pakość deposit (Kujawsko-Pomorskie Voivodeship), which is placed in the chapter "Quartz sands for production of cellural concrete and lime-sand brick" (classification according to the geological documentation).
Prapared by: Wojciech Szczygielski