Vitrified Bottom Ash Slag from Municipal Solid Waste Incinerators-phase Relations of CaO-SiO2-Na2O Oxide System
During incineration of municipal solid waste (MSW),some heavy metals and other environmentally harmful elements are liberated into bottom ash.The stricter environmental regulations require a higher immobilization efficiency of the ash before its safe disposal and application.Vitrification is one of the promising options,and has the advantages of high destruction efficiency of organics,high immobilization of heavy metals,and large volume reduction.The main components of the vitrified slag are SiO2,CaO,Al2O3,Fe2O3,Na2O and MgO,and the compositions have direct effect on the glass formation during vitrification,and further on the physical and mechanical properties of the slag.To provide essential data for the utilization of bottom ash as vitrified slag,the phase relations and thermodynamic properties of the oxide system need to be systematically investigated.In the present study,the liquidus temperature of the typical vitrified bottom ash slag was determined by using differential scanning calorimetry (DSC) measurement.High temperature equilibrium experiments were conducted to investigate the phase relations of the sub oxide system of CaO-SiO2-Na2O by means of Scanning Electron Microscopy (SEM),Electron Microprobe Analysis (EMPA) and X-ray Diffraction (XRD).The results show that the melting temperature of the vitrified bottom ash is around 930℃.In the CaO-SiO2-Na2O system with less than 50 mol% SiO2,the liquidus temperature decreases with increasing amounts of Na2O along the tie-line of Na2O-Ca3Si2O7.Two compounds Na2Ca3Si2O8 and Na4Ca8Si5O20 are identified in the oxide system.
Bottom ash Vitrification DSC Phase relations
Z.Zhang Y.Xiao J.H.L.Voncken Y.Yang R.Boom
Metals Production,Refining and Recycling,Department of Materials Science and Engineering,Delft University of Technology.The Netherlands
国际会议
XXIV International Mineral Processing Congress(第24届国际矿物加工大会)
北京
英文
3575-3581
2008-09-24（万方平台首次上网日期，不代表论文的发表时间）