Activation of the combustion of low-reactivity solid fuels with metal-rolling production waste

Abstract

The effect of the addition of different amounts of metal-rolling production waste (metal scale in amount of 1–10 wt%) on combustion characteristics of low-reactive solid fuels (anthracite and semi-coke) was studied. XRD analysis of the metal scale identified Fe3O4 and Mn3O4 phases along with a cubic Fe phase. The characteristics of ignition and combustion of the samples were studied via thermal analysis and high-speed video recording at heating medium temperatures of 600–800 °C (with 100 °C step) using a combustion chamber. It was experimentally found that the addition of a metal scale, regardless of its weight content, increases the fuel reactivity, as evidenced by the drop in temperature of the onset of intense oxidation (ΔTi) by 2–32 °C and the decrease in the ignition delay time (Δτi) by 0.2–2.2 s. The metal scale additive also increases the fuel combustion rate, which was evidenced by the maximum rate of oxidation (Δwmax) increasing by 0.1–2.0 wt%/min and, hence, the temperature of the end of oxidation (ΔTf) reducing by 13–68 °C. Due to combustion intensification, the carbon content in ash decreased by 55 rel% on average. The amount of CO and NOx contained in gas-phase combustion products diminished as well.