• Resources Recycling
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• v.23 no.1
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• pp.40-47
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• 2014

Feasibility of utilizing unburned carbon residue in coal ash as a potential precursor for the production of activated carbon was assessed to seek for solution to recycle unburned carbon residue. The unburned carbon concentrate generated from the 4 stages of cleaner flotation has a grade of 87% carbon. The crystalline impurities in the concentrate included quartz and mullite. Unburned carbon had a low specific surface area of $10m^2/g$, which might be related to a high degree of coalification of domestic anthracite coal. Carbon particles were mostly porous and have a turbostratic structure. When 1g of carbon was activated with 6g of KOH powder, the highest specific surface area value of $670m^2/g$ was achieved. Low wettability of unburned carbon particles, which was resulted from high temperature combustion in a boiler, might cause poor pore formation when they were activated by KOH solution. The activated carbon produced in this study developed micropores, with an equivalent quality of general-purpose activated carbon made from coal. Hence, it is concluded that chemically treated unburned carbon can be used for water purification or an alternative to carbon black as it is.