Effect of CaCO3 on roasting denitrification of secondary aluminum ash
The utilization process of aluminum resources will produce a large amount of aluminum ash,which is a dangerous solid waste. Based on the systematic analysis of the thermodynamics of AlN roasting denitrification,the effect of CaCO3 on the denitrification of secondary aluminum ash at different roasting temperatures,time and ingredient ratios was investigated. The process mineralogy,phase change and denitrification rate of secondary aluminum ash were studied by XRD,SEM,EDS,distillation-neutralization titration and other methods. The results show that there are many active phases,such as Al and AlN in the aluminum ash. In the temperature range of 400-1600 ℃,the N element in the AlN in the aluminum ash is most likely to be converted into N2 after high temperature roasting. The content of AlN in the secondary aluminum ash can be effectively reduced by increasing the temperature appropriately. The long roasting time has little effect on the content of AlN in the secondary aluminum ash. CaCO3 as a denitrification agent,the optimum denitrification process parameters are ingredient ration mCaCO3:mash of 0.6,calcination temperature of 1100 ℃,calcination time of 240 min. The main phase of secondary aluminum ash is 2CaO·2Al2O3 after calcification roasting,and the denitrification rate of secondary aluminum ash is 98.37％.
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