The Study Of Semi-dry Desulfurization Ash Utilization Technology

The semi-dry flue gas desulfurization technology has attracted much attention fromelectric power enterprises with the advantages of simple equipment, low running cost,small occupied area, high desulfurization efficiency and low investment cost, and hasbroad market prospects. The desulfurization product has complex components, togetherwith the recognition and research degree of it are also insufficient, most of thedesulfurization product is disposed by the way of stacking or discarding, all of this madea tremendous negative effect on the environment. Therefore, a preliminary study wascarried out on the basic properties and application techniques of desulfurization product inour paper, to find an effective way of resource utilization.By analyzing three kinds of desulfurization ash’s physic-chemical characteristics, wefind that the main phases of the desulfurization product are calcium carbonate, calciumoxide, calcium hydroxide, calcium sulfate, calcium sulfite and quartz, and the particle sizeis0.045mm~0.5mm, in which0.076mm~0.154mm particles accounted for57%~64%.Due to the existence of free calcium oxide, desulfurization ash has certain self-hardeningtrend; and the calcium sulfite contained in the desulfurization ash causes a certain sideeffects on the producing process of building materials.Using metal oxide as the catalyst, we studied the transformation of calcium sulfite tocalcium sulfate. The effects of various factors on the process, such as temperature, catalyst,time, Oxidizing agent etc., were investigated. Catalyst D and F has positive synergisticeffect on the catalytic conversion of calcium sulfite, and the optimal ratio is4:6.Desulfurization ash was modified through0.5%composite catalyst Z (catalyst D:F=4:6)incorporated17.2%hydrogen peroxide (10%), aged48h at20℃, and then autoclavedfor10h at174.5℃, and the calcium sulfate conversion rate reached44.5%.Industrialized application showed that the technology of using catalyst and hydrogenperoxide to modifying desulfurization ash to produce autoclaved brick is feasible, theproduct conformed to “Fly Ash Brick JC239-2001” with the strength grade of MU10, Thedosage of lime and gypsum was reduced by13.6%and37.5%respectively comparedwith ordinary process. It is find that the hydration products are mainly tobermorite, CSH(Ⅰ) and water garnet by SEM and XRD.The economic and technical analysis for the plan which use the modified desulfurization ash and fly ash as the main raw materials was done, and the results is that75000tons of fly ash and35000tons of desulfurization ash will be consumed with180acres of land be saved at the output of50000000standard brick per year, which show thesigificant social benefit and economic benefit.