Influence of briquetting on thermal behavior of bituminous coal oxidized during storage

Abstract Mini-briquettes of three types were studied with respect to their influence on the changes in volume of the carbonized charge of an oxidized coal. The briquettes were prepared from the same coal with additives in the amount of 2 wt%. The loading of briquettes with coal pitch, novolac, and lignite into the charge reduced the increase in charge volume at the stage of grain swelling quadruple, thrice, and twice appropriately and led to formation of a more compact residue after coking. The pyrolysis of the studied coal with additives was carried out in a TG/FT-IR installation. It was established that the type of additive influences the composition of volatile products of pyrolysis. The densification of the blend of coal with additive reduces not only the yield of volatiles but also the contribution of saturated and unsaturated hydrocarbons in these volatiles. The SEM data show the presence of deposits of various shape in the material of the mini-briquettes with addition of pitch and lignite. The EDS results show that there are atoms of C, O, Fe, Ca, S, Mg, Al, and Cl present in the deposits. This implies that the inorganic species, which accumulate in the form of deposit during cooling, are present in the composition of volatiles emerging in the mini-briquettes with pitch and lignite. The results of XRD analysis prove that all additives facilitate a greater ordering of the structure of mini-briquette material.