Combustion Characteristics and NO Emissions during Co-Combustion of Coal Gangue and Coal Slime in O2/CO2 Atmospheres

Coal slime has low ash content, and adding coal slime during coal gangue combustion may have influence on combustion character; and at this process, NO will emit, and lead to environmental pollution. O2/CO2atmosphere is conducive to NO emission reduction. Thus combustion characteristics and NO emissions during co-combustion of coal gangue and coal slime in O2/CO2atmospheres were studied. The results showed the addition of coal slime increased the combustion activity of the mixed fuels in both air and O2/CO2atmospheres. During co-combustion, there are synergistic effects between them at the fixed carbon combustion stage, and higher blending ratio of coal slime leads to stronger synergistic effect. Furthermore, this study also showed that with the increasing of coal slime blending ratio, the emission concentration of NO increases gradually; with the increase of temperature and O2concentration, the NO emission concentration also gradually increases, and higher O2concentration leads to shorter time required for the complete release of NO. Besides that, the results also demonstrate that the proportion of pyrrole and nitrogen oxide in the ashes increases with the increase of combustion temperature, and pyridine and quaternary nitrogen gradually disappear, while the total nitrogen content in ash decreases with the increase of temperature. The results will contribute to a better understanding of the co-combustion process of coal gangue and coal slime in O2/CO2atmosphere, and provide basic data for the practical industrial application of coal gangue and slime.