Comparison of the catalytic effects of eight industrial wastes rich in Na, Fe, Ca and Al on anthracite coal combustion

The catalytic effects of eight industrial wastes rich in Na, Fe, Ca and Al on Jincheng anthracite coal combustion were compared. The thermogravimetric experiments showed that Na-rich brine sludge (BS) and salt sludge (SS) exhibited better catalytic effects on coal combustion than Fe-rich iron mud (IM) and steel residue (SR). However, IM and SR exhibited better catalytic effects than Ca-rich white lime mud (WLM) and calcium carbide residue (CCR). Among the eight industrial wastes, Al-rich alumina residue (AR) and aluminium slag (AS) demonstrated the worst catalytic effects. BS, which contains more Na (mainly in the form of NaCl, which was equivalent to Na2O with a content of 13.14%) than SS (mainly in the form of NaCl and Na3Mg(CO3)2Cl, which were equivalent to Na2O with a content of 7.64%) does, reduced the ignition temperature of Jincheng coal from 582 °C to 561 °C because of the promoted transfer of oxygen to the carbon surface through the cyclic oxidation and reduction reactions between Na2O and Na2O2. IM, which contains more Fe (mainly in the form of γ-Fe2O3, which was equivalent to Fe2O3 with a content of 92.22%) than SR (mainly in the form of Fe2SiO4 and α-Fe, which were equivalent to Fe2O3 with a content of 8.29%) does, reduced the ignition temperature of Jincheng coal to 569 °C as a consequence of the enhanced transfer of oxygen to the carbon surface through the cyclic oxidation and reduction reactions between FeO and Fe2O3.