Microwave Drying of Anthracite: A Parameter Optimized by Response Surface Methodology

Response surface methodology, based on Central composite design, was applied to obtain the optimized parameters for microwave drying on anthracite. The microwave power level, drying time, and sample mass were selected as the independent variables for the experiments, while the dehydration ratio was selected as the response affected by the independent variables. The significance of these three variables are in reverse order: drying time a parts per thousand << sample mass > power level. The interactions between drying time and power level, power level, and sample mass were significant; the interaction between drying time and sample mass was insignificant. The optimization conditions were the following: power level of 682.07 W; drying time of 2.98 min; and sample mass of 49.19 g. The maximal effectiveness ratio is 1.452 kg/kW h under the optimized condition. The verification experiment indicated that the experimental results were in good agreement with the predicted values, which has only a +0.57% deviation.