Reactivity of Physically and Chemically Clean Coals

In this study, a total of 12 coal samples were collected. In order to have reactivity determination samples were thermo-gravimetrically analysed. Thermo-gravimetric analysis was carried out not only on physically clean coal samples but also on chemically clean coal samples. Reactivity program within thermos-gravimetric analysis consists of volatiles burning in N₂ atmosphere which is fast reaction and residual carbon burning in dry air atmosphere which takes places right after. Reactivity parameter for each coal sample is considered as an important parameter since it characterize the burning profile of residual carbon matter after de-volatilization. In order to have reactivity determination, samples were objected to temperature increase up to 700 °C in N₂ atmosphere and then the temperature was set to 500 °C in dry air atmosphere. Reactivity of each corresponding sample after physical and physical-chemical cleaning was determined. The determined reactivity (R₅₀₀) values changed between 0.06 and 0.221 for physically clean coal samples and they are between 0.11 and 0.24 for the chemically clean coal samples. Reactivity (R₅₀₀) values increased after chemical cleaning. Due to coal structure difference, the increase in reactivity (R₅₀₀) after chemical cleaning is different for each sample. For example for TB6 sample, reactivity (R500) increased more than 60 % while for TB5 sample it only increased by 6 % after chemical cleaning. Chemical cleaning followed by physical cleaning results in increase in reactivity and this increase depends on the nature of the coal type. (paper)