Preparation Of Ecological Building Materials By Semi-Dry FGD Ash And Process Parameter Optimization

Semi-dry FGD technology has some advantages, such as simple process, small space-occupy and no sewage discharge, but the output of byproduct—desulfurization ash is higher, which is composed of calcium sulfate, calcium sulfite and residual desulfurizer etc. Desulfurization ash is a potential resource, direct stacking and landfill is the mainly approach ,which is not only cause environmental pollution, but also a waste of useful resources. Therefore, the comprehensive utilization of ash on desulfurization research become the current pressing problems, and also a constraint to the development of flue gas desulphurization technology .In this paper, chemical composition, physical properties, particle orphology ,thermal stability of the three kinds of desulfurization ash were analysised and studied by odometric method and scanning electron microscopy, X-ray diffraction, particle size distribution, TG - DTA and other modern analytical methods.The results are as follows.1) There is no significant difference in chemical composition of the three desulfurization ash.Phase composition are mainly CaSO3, CaSO4, CaCO3, corundum and mullite, etc.Steel desulfurization ash has lower content of CaSO3 and MgO ,while the higher content of CaO and Fe2O3.2) Steel desulfurization ash particle size is 7.24 ~ 8.06μm, with median diameter is 5.83μm; while the power plant desulfurization ash particle size is222.66 ~ 247.83μm, with median diameter, respectively 206.68μm, 208.11μm, therefore steel desulfurization ash particle diameter is less than diameter of power plant desulfurization ash.3) The research on steam-cured brick preparated by desulfurization ash, fly ash as main raw material, admixing a certain amount of excitation agent, aggregate,Studies have shown that the optimal ratio of 2# ash turn are as follows: desulfurization ash25%, fly ash49%, sand and gravel aggregate than the 2:3 of 25%, 1% of the compound activator NH; 3# ash turn: desulfurization ash40%, fly ash34%, sand and gravel aggregate than the 2:3 of 25%, 1% of the compound activator NH. Based on the optimal formula , the main process parameters were studied, water 25% , digestion time 36h,24h, curing 7 h at 90℃,8h at 95℃.2# desulfurization gray bricks on the durability test carried out:frost resistance and shrinkage of the steam-cured bricks perform well and the technical performance can meet the requirements of MU15 in"fly ash brick"(JC239-2001). In industrialized expanding test, prepared standard brick and hollow bricks for compressive, flexural strength, 15 times the loss rate of freeze-thaw cycles, dry shrinkage value of the test that its indicators are in line with "puzzle wall test method"(GB/T2542-2003)and "fly ash bricks"(JC239-2001).