Study On The Effects And Control Methods Of Chloride Ions On The Properties Of Desulfurization Gypsum And Its Products

Coal-fired power generation is the main form of China electric power industry at all time,and this electric power structure won’t change in the foreseeable period. However, SO2andother harmful gases generated by coal combustion are important factors which causeenvironmental pollution. In order to respond to the call of the country on Sustainabledevelopment of resources and environment, flue gas desulfurization (FGD) appears.Desulfurization gypsum is the byproduct of flue gas desulfurization, which main component isdihydrate gypsum. Desulfurization gypsum and natural gypsum have a lot in common.Moreover, in consideration of its advantages of high yield, low cost and so on, desulfurizationgypsum is the optimum substitute of natural gypsum. Because of particle morphology, impurity,desulfurization gypsum and natural gypsum also have many differences on many aspects.Therefore, it has great significance to study on the comprehensive utilization of desulfurizationgypsum.Calcined System is a key factor to determine the performance and application condition ofdesulfurization gypsum. Phase transition temperature range was analyzed by means ofthermogravimetric analysis for desulphurization gypsums. These desulphurization gypsumshad been prepared by heat-treatment processes under different calcination temperatures. Forproducts made of desulphurization gypsum prepared by different calcined systems, physicalperformances were studied and compared through micro-analysis methods (XRD, SEM etc.).After thorough study and comprehensive analysis, the best calcination temperature is180℃fordesulphurization gypsum when it is calcined for1.5h.As a major impurity element in desulfurization gypsum, chloride ion has an importantinfluence on the performance of desulfurization gypsum and its products. Chloride ion indesulfurization gypsum exceeds the standard in most cases, which directly leads to differentperformance of different desulfurization gypsum products. This paper has studied the effects ofchloride ions on the properties of desulfurization gypsum. We have made a comprehensiveanalysis of the cause for this phenomenon with the help of micro-analysis methods (XRD, SEM,etc.). Results have shown that, the chloride ions have a great impact on the desulfurization gypsum and its products on many aspects of performance, how to take effective measures toreduce the adverse effects of chloride ion will be the focus of future research work.In order to find the method of lowering the effects of chloride ions on the properties ofdesulfurization gypsum products, change the application status of FGD gypsum and improve itsindustrial additive value，this paper has studied the effects of organosilicon waterproofing agent,minerals and water gypsum ratio on the transfer condition of chloride ions in desulfurizationgypsum and its products (take plasterboard for example). Results have shown that, dopingmoderate waterproofing agent could not only improve the adhesion property of plasterboard,but also ameliorate water resistance. Optimum mineral admixture could improve chloridebinding capacity with no adverse effect. Water gypsum ratio has a great impact on the transfercondition of chloride ions and the adhesion property of plasterboard. In the premise of doesn’thinder its workability, the lower water gypsum ratio, the higher chloride binding capacity. Wehave synthesized a kind of admixture and mineral compound fixed chloride agent, which basestock including waterproofing agent, cement, flyash, slag and water reducing agent. Theoptimal dosage of them are1%,1.2%,2.4%,3.6%and2.2%respectively.