Effects of natural minerals on the combustion characteristics of pulverized coal

The effects of five natural-mineral additives on the combustion characteristics of anthracite were investigated with a synthetical thermal analyzer. The five natural-mineral additives are DG-dolomite, RF-humite, DR-humite, LL-limestone and calcite. Combustion characteristic parameters such as ignition temperature, maximum combustion rate, release property index and burn-out characteristic index were studied by thermo-gravimetric analysis, and the kinetics parameters of samples such as activation energy and frequency factor were also calculated. Experimental results show that DG-dolomite, RF-humite and DR-humite can promote the combustion of anthracite, decrease the ignition temperature, increase the release property index and burn-out characteristic index, and make the maximum rate of combustion move ahead the volatile matter combustion contemporaneously; nevertheless, LL-limestone and calcite have the opposite effect. Kinetics calculation results reveal that the addition of DG-dolomite, RF-humite and DR-humite decreases the activation energy by 10.4%, 14.5% and 10.7% respectively, and the decrease has a combustion-supporting effect in the combustion of blends. Adding LL-limestone and calcite increases the activation energy by 2.0% and 4.3% respectively, and the increase exhibits a fire-retardant effect in the combustion of blends.