The Study And Process Design For Comprehensive Utilization Of Fly Ash

China use coal as main energy source,in the total amount of primary energy,coal accounts for 90%.At present,China's coal resources of about 75%were used for thermal power generation,which produce large amount of fly ash.Only a small part is reused.Most fly ash were piled up.The main chemical components of fly ash are SiO2,Al2O3,CaO,Fe2O3,MgO,Na2O,K2O and unburned carbon,as well as some rare elements.The content of silica,alumina and iron oxide accounts for more than 85%of fly ash.Thus,the fly ash is a potential resource with high value.This experiment use predesilication process to obtained silica from fly ash.In addition,calcination and acid leaching were used in the extraction of aluminum.Best conditions for predesilicon:ratio of liquid to solid:2/1,NaOH concentration:20%,temperature:150?,time:2h.Under this condition,the silica dissolution rate is 92.43%,the water glass modulus is 1.08.Best conditions for preparing aluminium hydroxide:ammonium sulfate and fly ash mass ratio:2.5/1,sintering temperature:450?,sintering time:2h,leaching temperature:70?.In this study,the design of a fly ash factory that can process 100000 tons per year was done.The design was based on experiments and calculation.For example,the unit operation's material balance and heat balance calculation.