Composition and morphology of char particles of fly ashes from industrial burning of high-ash coals with different reactivity

Unburned carbon from coal combustion ash: An overview

“…Results consistent with this observation were reported in [89,90]. So the results described in literature [4,31,77,78,[82][83][84][85][86][87][89][90][91] are consistent in terms of lowrank-coal UC distribution within the PFC FA fractions. However, in the case of higher-rank coals, the results are somewhat different.…”

“…However, class of FA can also have some effect [87] on UC distribution within FA particle-size fractions. Fundamental characteristics of class F FA and class C FA are given in Table 1 showing that class F FA originates from higher rank coals whereas class C FA is derived from lower rank coals.…”

“…Sharonova et al [87] concluded that UC particles of class C FA tended to be enriched in coarse FA fractions (N 0.18 mm). However, UC particles of class F FA are distributed in all fractions, with the maximum within the range of 0.06-0.07 mm for anthracite-derived UC and in 0.045-0.106 mm fractions for bituminous-coal-derived UC.…”

“…Network type chars are abundant in ashes of low-rank coals (R o b 0.6; V daf N 30%), cenospheric type in ashes of medium-rank coals (R o 0.6-2.0; V daf 10-30%) and solid type prevails in ashes of high-rank coals (R o N 2.0; V daf b 10%) [87,172,185].…”

“…In case of PFC, this influence is described in [72,189]. For high-rank coals, quite low values of SSA have been reported [87,82,83,181,192,155,211,132] usually falling within the range of 10-80 m 2 /g. In case of low-rank coals, SSAs are much higher; they started at 200 m 2 /g and can reach up to 400 m 2 /g [87,91,181,192,211,212].…”