The advantages of microwave in using engineering spoil to sinter bricks

Abstract

The difference in process parameters and sintering mechanism between microwave sintering and conventional sintering is studied in this thesis. The muffle furnace is adopted to simulate the conventional sintering. The engineering spoil is used as the raw material to prepare green bodies with different water-material ratios. By testing the weight loss on ignition, sintering shrinkage, water absorption, compressive strength, microstructure and crystalline composition of spoil bricks with different water-material ratios, the effects of the two sintering technologies on the performance of spoil bricks were compared to reach the best solution. The sintering mechanism of spoil bricks in CS and MWS was discussed through linear regression analysis. Through leaching toxicity analysis, the leaching toxicity of raw materials and spoil bricks was tested. The results show that compared with CS, MWS has higher efficiency on ignition, lower energy consumption, and better fixation effect on toxic metal elements. The MWS bricks have greater weight loss on ignition, sintering shrinkage and compressive strength, and lower water absorption. Both technologies will transform the mineral crystals in the raw materials into more stable crystals with basically the same composition through phase change. But the microstructure of the spoil bricks using MWS is denser. Besides, as the moisture content of the green bodies increases, the sintering efficiency of MWS will decrease, while the reverse is true for CS. With the increase of the water-material ratio, the weight loss on ignition and water absorption of MWS and CS bricks will increase, but the sintering shrinkage rate and compressive strength will decrease. In summary, MWS, with a better comprehensive performance, is more efficient and energy-saving than CS, the optimal forming water-material ratio for MWS technology is 0.14.