Research of the Enrichment of Ash and Slag Waste from Coal Combustion at Thermal Power Plants Using the Flotation Enrichment Method

When burning coal, a significant amount of unburned or partially burned coal particles, called “underburning”, turns out to be in the ash. The extracted underburning is a valuable component and can be used as a secondary fuel mixed with the main one, in the manufacture of fuel briquettes, as a rubber filler instead of graphite and a filler of electrically conductive concretes used in the construction of some elements of a nuclear power plant. Flotation is an effective method of extracting unburned coal particles. In this work, a flotation enrichment method has been proposed for the extraction of carbon concentrate from ash and slag waste from thermal power plants. The influence of the reagent regime, the size of the material, as well as the use of pre-activated ash and slag waste after the chemical activation process on the efficiency of flotation enrichment have been comprehensively studied. The phase composition and the morphology of ash and slag waste have been analyzed by using X-ray diffraction and scanning electron microscopy. Compared with the traditional method of flotation enrichment of ash and slag waste, the use of pre-activated ash and slag waste under optimal conditions has showed the efficiency of carbon extraction into carbon concentrate from 26.6 to 65%. The results of the experiments conducted by using the reagent mode of the kerosene collector 1500 g/t and the MIBK 50 g/t foamer are as follows: a carbon concentrate with a carbon content of 65% has been obtained, carbon extraction into the concentrate has been 37.6%, the yield has been 4.14% when using activated ash and slag waste.