Effects of Microwave Heating on Pore Fractal Properties of Blast Furnace Sludge

Effects of microwave heating on the pore fractal properties of blast furnace sludge (BFS) and relative mechanism were studied. The results show that the morphology features of iron bearing sinter and coke particles, which are the main constituents of the BFS, were remarkably changed by microwave heating. The porosity, surface roughness and specific surface area of modified particle surface all increased obviously. Combining with fractal method called Sierpinski model, the fractal dimensions of sinter, coke and others increased from 2.35, 2.24 and 2.58 to 2.65, 2.44 and 2.61 respectively, after modification by microwave heating. The results predicted that the reaction mechanism of microwave heating for BFS is related to two aspects. Different mineral phases existed in BFS particles incline to dissociate each other due to their dfferent microwave absorbability; some recombination or reconstructon of matters or structure leads to structure defects, which have great influences on the surface morphology characteristics and chemical properties. The research indicated that fractal dimension can be used as an effective factor for quantitative analysis of the pore changes in morphology of the sludge. Furthermore, it is helpful for separation and extraction of valuable constituent from BFS.