(454a) Desulfurization of Coal Using Microwave Assisted Chemical Treatments

India has a multi-fuel scenario in which as much as 46% is covered by non-commercial fuels such as fire wood, animal dung etc., while the commercial fuels like coal, oil and nuclear fuels cover 54 % of the total energy demand. Coal has established itself as dependable, commercial and prime energy source. But its complete utilization cannot be achieved because of the presence of high levels of sulfur. Although Indian coals are low in sulfur but certain reserves in the north-eastern region such as Assam coals, contain high percentage of sulfur. Selective heating by microwave exposure acts as a source of weakening or breaking of bonds. Experiments were conducted to explore the feasibility of desulfurization by microwave radiations. Chemical methods using acid, alkali and solvent vapour extraction of coal along with microwave irradiation were also investigated. Microwave irradiation as pre-treatment method was adopted for simplification of coal structure so that enhanced desulfurization could be achieved. Treatment with microwave followed by solvent vapour extraction resulted in more than 60 % sulfur removal. Speed was the salient feature of desulfurization with microwave treatment. Microwave treatment of alkali-coal, slurry was a one step process, which resulted in significant reduction in total sulfur value and required no other treatment. Chemical and infrared analysis indicated the removal of not only pyritic sulfur but also organic sulfur from Desulfurization by microwave appears to be successful technique, capable of removing all forms of sulfur without affecting coal structure and coking characteristics. Alkali-coal slurry samples on irradiation yielded better results as compared to the dry-coal samples on microwave exposure. The only constraint in adopting microwave-desulfurization process is the economic factor.