The Research Of Life Cycle Assessment About Phosphogypsum Utilization

Phosphogypsum is a byproduct of industrial phosphoric acid, the main ingredient is CaSO4·2H2O, is a can make use of solid waste. Phosphogypsum with high yield, great harm, the comprehensive utilization rate is low, has become one of the important factors that restrict the phosphorus chemical enterprises. At present most of phosphorus gypsum treated by open storage, not only takes up a lot of land, but also water, air and other environmental impact on the surrounding. Do a lot of research at home and abroad of phosphogypsum decomposition mechanism, application and so on, with phosphogypsum as cement production process for the production of sulfuric acid instead of natural gypsum has been a large number of industrial applications, and as an important means of Phosphogypsum Resource widely, but because of the phosphogypsum decomposition mechanism is complex, large, effects of impurities high energy consumption problems, utilization of the resources in a way in recent years gradually remain stagnant. With the development of application and fluidized bed process of new cement technology, technology of circulating fluidized bed for decomposing phosphogypsum cement clinker cogeneration sulfuric acid gradually into the people’s vision, the circulating fluidized bed put phosphogypsum decomposition part separately, both full reaction in favor of phosphogypsum, and energy consumption of reaction decreased, has good prospects for development and economic benefits.The mechanism of the former decomposition of phosphogypsum phosphogypsum decomposition process, and the product properties and influence of impurities carried out extensive and in-depth research, based on the comprehensive utilization of phosphogypsum, introduced the life cycle assessment international, currently has a comparative analysis of technology of circulating fluidized bed better prospect decomposition phosphorus gypsum cement technology and still use the industrialization hollow rotary kiln decomposing phosphogypsum cement clinker, to find a more optimal use of phosphogypsum, for energy-saving emission reduction and process improvement to provide advice and guidance. The main research contents are as follows:Firstly, by using a thermodynamic calculation software FactSage6.1, the mechanism of phosphogypsum decomposition process was simulated, the comparison of high sulfur coal (C) and CO two catalysts. The reaction mechanism, select the appropriate reaction conditions for circulating fluidized bed process. The results show that, as a catalyst in the coal, the reaction temperature is900℃, CaSO4decomposition heat of absorption for581.00kJ/mol, but the reaction process of side reaction, in actual operation, attention should be paid to control conditions. As catalyst in CO, reaction temperature1000℃, reaction heat of absorption for202.944kJ/mol decomposition; and carbon as reductant decomposition reaction phase, reaction temperature100℃, but the reaction is endothermic reduction of300kJ/mol. To facilitate comparison of traditional craft, we use high-sulfur coal decomposition of phosphogypsum cement clinker process.Secondly, the introduction of life cycle assessment, object and scope mainly selected the calcination stage two process of cement clinker as life cycle assessment, through processing and analysis data list, the cement calcining stage, the relative order index of environmental load for the two processes of size EDP> ADP> GWP> HT> AP> LE> EP. From the reaction energy point of view, circulating fluidized bed process heat for5119kJ/mol, a hollow rotary kiln process7118-7536kJ/mol, the heat consumption is reduced by28%-32%. In the whole process, reduced energy consumption, reduced CO2emissions, the future development of the route one must take the extensive use of industrial waste to replace natural material is cement industry.Thirdly, the results of weighted analysis showed that, comprehensive environmental load of circulating fluidized bed technology for1.928(E-14/a), hollow rotary kiln process is superior to the traditional (2.213E-14/a), the improvement of the circulating fluidized bed technology and eliminate the impurity effect is the focus of future research, also has laid the foundation for the promotion of this process.