The Miocene Lacustrine Chalk from Lignite Bełchatów Deposit (Poland)—Structural and Textural Character and SO2 Sorption Properties in the Fluid Combustion Conditions

Abstract

The Miocene lacustrine chalk in the Bełchatów lignite deposit is one of the most important accompanying minerals. It is found in three lithological varieties: white, dark and silicified. It is selectively operated and stored on anthropogenic deposits, representing the mineral resource base. The article presents the results of research on lacustrine chalk from the Szczerców mine excavation and accumulated on the anthropogenic deposit (the Szczerców field external landfill) regarding the possibility of using SO2 sorbent in the fluid combustion technology. It has been shown that primarily the structural and textural parameters of the rock, and to a lesser extent, the CaCO3 content, are responsible for the high efficiency of SO2 sorption. It has been proven that in this type of technology, the presence of carbonised plant matter only seemingly lowers the quality parameters of the raw material. It has a significant impact on the sorption properties, effectively influencing the expansion of porosity and specific surface during thermal decomposition. The expansion of the surface is mainly based on the pores on the border of mesopores and macropores, i.e., pores considered to be sorptive towards SO2. These pores, because they are formed in a lower temperature range than the calcite thermal dissociation process and are connected together to form a system, act as diffusion channels of CO2 from inside and SO2 into the inside of the sorbent grains, intensifying the decarbonisation and SO2 sorption processes.