Combustion characteristics and thermodynamic analysis of lake sediments

The sediment in the lake is a mixture of clay, organic matter and various minerals.It contains SiO₂, Al₂O₃, CaO, MgO, K₂O, Na₂O and some organic materials which can be used as raw materials for roasting ceramics or other sintered products.Some sediments derived from a lake in Huangshi city, Hubei province was selected to measure the loss on ignition and the content of organic matter.XRF, ICP-OES and XRD were used to study the physical and chemical properties.Synchronous thermal analysis-mass spectrometer(TG-DSC-MS) was used in thermal analysis, and thermal analysis kinetic calculations were performed based on the results of the thermal analysis.The results show that the main components in the sediments are quartz, calcite, magnesium calcite, mica and such on.The organic matter content is 10.86%, the loss on ignition is 14.19%, the content of S is 0.39% and P is 0.13%, and there is a small amount of heavy metals.The gas release during the combustion of lake sediment mainly occurs in the stage of 120-750 ℃.The main gases are CO₂, H₂O, NO, NO₂, et al.The different heating rates have no obvious effect on the combustion process of lake sediment.The combustion of lake sediment can be divided into two stages, the first-order reaction model of Coats-Redfern method can describe the combustion process of lake sediment well.The activation energy of lake sediment in the first stage is about 22.00 kJ/mol.So the reference is given to the control of the reaction mechanism and the research on the curing mechanism of the preparation of sintered products in lake sediments.