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 increased in 2014 by 0.25 million tonnes (in comparison with 2013) and were reported to be equal 276.54 million tonnes. There was new documentation with recalculated resources approved for Lechówka dz. 102/1, 99 deposit (resources increased by 246 thousand tonnes).
Deposits of clay raw materials for cement production (together with building ceramics raw materials) are presented on the map.
Exploitation has been carrying out only in Lubelskie Voivodeship area for Chełm cement factory. In 2014 the output was not recorded from deposits described in this chapter. However, it was replaced by the loess raw material which was exploited from Buśno deposit (Lubelskie Voivodeship). Buśno deposit is covered in the chapter “Building ceramics raw material”. In 2014 the output amounted to 101 thousand tonnes (51 thousand m3).
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). The output amounted to 104 thousand tonnes (61 thousand m3) in 2014.
Prapared by: Wojciech Szczygielski