Environmental Potential of Using Coal-Processing Waste as the Primary and Secondary Fuel for Energy Providers

The main anthropogenic emissions (CO, CO2, NOx, SOx) produced by the processing (combustion) of wastes (coal filter cakes) were measured directly for the first time. The research considered the most widespread coal filter cakes: those of nonbaking, low-caking, coking, flame, and gas coals. These filter cakes are regarded as promising components for the technologies of coal-water slurry (CWS) and coal-water slurry containing petrochemicals (CWSP). According to our estimates, the annual increment of such wastes in the world is as high as 100 million tons. Consequently, the effective utilization of these wastes in the power industry is of high interest. The evaluation of hazardous emissions from the combustion of such wastes shows that filter cakes produce a similar amount of CO and CO2 as the initially-used coals but filter cakes are more cost-effective. We have established that CWS and CWSP technologies can be used to reduce NOx and SOx emissions. To reduce CO and CO2 emissions when burning filter cakes, we need to switch to low-temperature combustion. Lowering the combustion temperature of filter cakes from 850 ◦C down to 650 ◦C decreases the underburning insignificantly while decreasing CO and CO2 emissions by 30–40%.