Drying of silica sludge using microwave heating

Microwave drying of silica sludge, which reduces its volume and mass is an important aspect for lowering its disposal costs. In this study, microwave heating and drying characteristics of wet silica sludge were investigated in a multimode microwave applicator, with a 1 kW, 2.45 GHz microwave source. Experiments were carried out under different power conditions (400–1000 W) using different sludge masses (10–1000 g). A simplified theoretical approach was applied to generate theoretical drying curves. Good agreement between theory and experiment was achieved over the heating-up and constant drying period. The values of the largest amount of material and the lowest power input that can result in shorter drying time and higher drying rate are determined to be 1000 g and 800 W respectively.