| CaO-SiO2-Al2O3-FeOx oxide system is not only one of the primary oxide sub-systems of CaO-SiO2-Al2O3-MgO-FeOx-Na2O oxide system generated during the vitrification of municipal solid waste incineration ash, but also an important slag system in metallurgy process. Therefore, the thermodynamic properties of CaO-Al2O3-SiO2-FeOx oxide system not only will provide the essential thermodynamic datas for innocent treatment of the incineration ash and sustainable utilization of the vitrified bottom ash slag, but also will contribute greatly to the production of high quality metal, and the utilization of lower grade metallurgical raw materials.By taking the CaO-Al2O3-SiO2-FeOx, CaO-Al2O3-FeOx and SiO2-Al2O3-FeOx oxide systems as the research objects, based on thermodynamic software package FactSage6.1, a comprehensive study involving the combination of the high temperature equilibrium experiments with the thermodynamic modeling (CALPHAD assessment) was conducted to study the effect of temperature and oxygen partial pressure on the equilibrium phase relations and liquidus. The main conclusions are as follows.(1) According to the calculated results with FactSage6.1, the effect of temperature on the the equilibrium phase relations and liquidus location of CaO-SiO2-Al2O3(8.3%)-FeOx oxide systems and its sub-systems was appreciable. The liquid regions enlarged with the increase of temperature from1573K to1873K, while the primary phase fields reduced distinctly. On the other hand, the effect of oxygen partial pressure on the liquidus location of primary phase fields of spinel solid solution phase in the SiO2including systems was remarkable, and little effect was considered on the liquid zone and phase relations of CaO-Al2O3-FeOx.(2) The high temperature experimental results showed that the effects of temperature on the phase relations and liquidus location in FcOx-lower area of CaO-Al2O3-FeOx system and the mullite primary phase field of SiO2-Al2O3-FeOx system were notable. The liquid zone expanded obviously with the increase of temperature.(3) The optimized quasichemical parameters for the liquid phase in CaO-SiO2-Al2O3(8.3%)-FeOx oxide systems were as the followings. qSiO2,Al2O3,FeO101=-389500,qSiO2,FeO,Al2O3011=896500,qSiO2,FeO,Al2O3101=-206500qCaO,Al2O3,FeO011=-596500,qCaO,Al2O3,FeO010=3000The calculated liquidus of CaO-Al2O3-FeOx and SiO2-Al2O3-FeOx systems based on the optimized and FactSage oxide solution database respectively showed that, comparing to the calculated results with FactSage6.1, the liquidus of CaO-Al2O3-FeOx shifted slightly to the high-Al region, and the shifting tendency decreased with the increase of temperature. For the SiO2-Al2O3-FeOx system, the primary phase field of mullite shifted toward the high-Fe area, and the stable region domain of mullite remained unchanged. |
PDF Full Text Request