The objective of this study was to evaluate the microwave drying characteristics of mixtures of chemical wastewater sludge (70~90%) and anthracite coal (10~30%) with respect to physical and economic factors such as mass, volume reduction, moisture content, drying rate and heating value when the wastes were dried at different weight mixing ratio and for different microwave irradiation time. The drying process were carried out in a microwave oven, the combined drying process with a 2,450 MHz frequency and 1 kW of power. Maximum dry rates per unit area on the microwave drying of mixtures with chemical wastewater sludge and anthracite coal were 35.5 kg H2O/m2·hr for Cs90-Ac10; 40.1 kg H2O/m2·hr for Cs80-Ac20 and 35.0 kg H2O/m2·hr for Cs70-Ac30. The result clearly indicated that moisture can be effectively and inexpensively removed from the wastes through use of the microwave drying process.

It has been studied that combustion and the production of air pollution of anthracite - bituminous coal blend in a fluidized bed coal combustor. The objects of this study were to investigate mixing characteristics of the particles as well as the combustibility of the low grade domestic anthracite coal and imported high calorific bituminous coal in the fluidized bed coal combustor. They were used as coal samples ; the domestic low grade anthracite coal with heating value of 2,010㎉/㎏ and the imported high grade bituminous coal with heating value of 6,520㎉/㎏. Also, the effects of air flow rate and anthracite fraction on the reaching time of steady state condition have been studied. The experimental results are presented as follows. The time of reaching to steady state was affected by the temperature variation. The steady state time was about 120 minute at 300scfh which was the fastest. It has been found that O_2 and CO_2 concentration were reached steady state at about 100 minute. It has been found that O_2 concentration decreased and CO_2 concentration increased as the height of fluidized bed increased. It was found that splash zone was mainly located from 25㎝ to 35㎝ above distributor. Also, as anthracite fraction increased, the mass of elutriation particles increased, and CO_2 concentration decreased. As air flow rate increased, O_2 concentration decreased and CO_2 concentration increased. Regardless of anthracite fraction and flow rate, the uncombustible weight percentage according to average diameter of elutriation particles were approximately high in the case of fine particles. As anthracite fraction and air flow rate increased, elutriation ratio increased. As anthracite fraction was increased, exit combustible content over feeding combustible content was increased. Regardless of anthracite fraction, size distribution of bed material from discharge was almost constant. Over bed temperature 850℃ and excess air 20%, the difference of combution efficiencies were little. It is estimate that the combustion condition in anthracite-bituminous coal blend combustion is suitable at the velocity 0.3m/s, bed temperature 850℃, the excess air 20%.