Preparation of sorbents using fly-ash from garbage incinerators and its performance in removing sulfur dioxide at high-temperature

The sorbents for removal of sulfur dioxide at high-temperature were prepared using seven fly ashes from different garbage incinerators. The desulfurization capacity of the sorbents (FA-sorbents) was measured using a flow type thermogravimetric apparatus. Results showed that the pore size distribution of FA-sorbents is larger than ca. 2000 nm, and the desulfurization capacities of FA-sorbents are higher than that of lime-sorbent. The mechanical strength of FA-sorbents was greatly improved, which contained additives of calcium sulfate. But its pore size was reduced; its desulfurization capacity was also decreased. FA-sorbents with 10% water-glass additive had a better desulfurization capacity than the FA-sorbents and its mechanical strength is equivalent to lime. And there was little change in its pore size. The reason for the better desulfurization capacity is that sodium in the water-glass can react with sulfur dioxide to form sodium sulfate.