Study On The Modification And Mould Gypsum Application Of FGD Gypsum

Flue Gas Desulphurization Gypsum, also known as FGD gypsum, is a kinds of theindustrial byproducts resulting from the process of Flue gas desulfurization and purification,and the Flue gas is generated by Industrial combustion of sulfur-containing fuels calciumsulfate dihydrate (CaSO4·2H2O) which Contain Two crystal water is the main component ofFGD gypsum which color is yellowish-white. With the world’s increasing attention toenvironmental protection and the rapid development of industrial technologies, as with ash,flue gas desulfurization gypsum has become another major solid waste. And due to the largeamounts of flue gas desulfurization gypsum on hold, not only to consume a large amount ofland resources, but also cause serious pollution of the ecological environment. In accordancewith the resource and study on the view of sustainable development, turning FGD gypsuminto treasure can both help desulfurization by-product gypsum emissions to achieve a virtuouscycleand protect the ecological environment to the benefit of mankind.FGD gypsum was taken as the research object, its basic properties, such as the flu gasdesulfurization gypsum’s chemical composition, phase composition, were studied by meansof chemical composition analysis, X-ray diffraction, scanning electron microscopy, andprobed into the enhancement mechanism of the α-type hemihydrate gypsum on calcinedgypsum from flue gas desulfurization. In allusion to the requirements of mold for resin-basedcomposite materials, it was emphasized that the calcined gypsum from flue gasdesulfurization was influenced by a variety of waterproofing agent, explored the modificationmechanism of polymer emulsion, paraffin emulsion, alunite expansion agent on the calcinedgypsum from flue gas desulfurization; and furthered using the polymer emulsion, the paraffinwax emulsion and alunite expansion agent synergism conducts the compound modifiedresearch to the composite modification of mould gypsum, prepared had the low waterabsorption performance desulphurization mold gypsum. In allusion to the requirements ofmold for ceramic materials, this paper also studied separately using the Modified gypsumwith high ratio of water to gypsum and modified foamed-gypsum to prepare the ceramic mold,and explored the role of modifier mechanism; the purpose, increasing as much as possible the water absorption of plaster mold under the premise of does not affect the mechanics strengthof plaster mold samples, is to meet the requirements of the ceramic body molding preparedwith high water absorption properties of the mold plaster.In the research on preparation of resin-based composite materials molding plaster mold,the calcined gypsum from flue gas desulfurization samples were treated by modificationthrough the waterproofing agent such as VAE emulsion、styrene-acrylic emulsions emulsion、paraffin emulsion、alunite expansion agent. The change rule and action mechanism withregard to the influence of waterproof agents on the properties of calcined gypsum from fluegas desulfurization samples were studied in this paper. The results indicate that: polymeremulsion with film properties could form intertwined irregular retinal within the pores ofcalcined gypsum from flue gas desulfurization samples in order to reduce the porosity andimprove the lap strength between the crystals of gypsum samples, so polymer emulsion has aobvious function for the gypsum products’ water proofing property and strength, the optimalcontent of VAE emulsion and acrylic emulsion are6%、4%, and the modified effects of VAEemulsions provide better than styrene-acrylic emulsions; alunite expansion agent’s hydrationcan generate ettringite and C-S-H gel which filling and blocking the wool stoma to improvethe lap strength between the crystals, so polymer emulsion also has a obvious function for thegypsum products’ water proofing property and strength, and its optimal content is4%. Thispaper also studied on composite modification of mould plaster through while adding6%ofparaffin emulsion,6%of VAE emulsion and4%of the alunite expansion agent in gypsum andobtained the good effect which above several kind of waterproof laboratory cannot achieve,so compound modifier can significantly reduce the water absorption of mold plaster sampleand improve the mechanical properties and softening coefficient of the mold plaster samples.Another experiment in this paper is the preparation of ceramic moulds. On the one hand,the method of improving ratio of water to gypsum on calcined gypsum from flue gasdesulfurization to prepare the Ceramic mold moulds is studied, in which the modifier aresulphoaluminate cement and carboxymethocel; and the change rule and action mechanismwith regard to the influence of modifier on the properties of calcined gypsum from flue gasdesulfurization samples were studied in this paper; the results indicate that: the best ratio ofwater to gypsum is0.743, the optimal content of sulphoaluminate cement and carboxymethocel are0.1%、8%. On another hand, this method of using the modifiedfoamed-gypsum to prepare the Ceramic mold moulds is studied, in which the modifier areretarder (citric acid、sodium borate、gelatin) and reinforcing agent (sulphoaluminate cement);the results indicate that: the foam’s optimum content is every200g of gypsum by adding150ml foam, the optimal retarder is sodium borate which optimum content is0.5%,sulphoaluminate cement’s optimum content is8%.