水库底泥和电石渣高温改性钢渣的研究

Study on the High-temperature Modified Steel Slag Using Reservoir Sediment and Carbide Slag

研究了复合改性剂(水库底泥+电石渣)高温改性处理对钢渣物相、结构、性能的影响,结合X射线荧光光谱(XRF)、X射线衍射(XRD)、扫描电子显微镜(SEM)、能谱分析(EDS)和粒度分析等测试方法,对原料的物化性质、改性钢渣的矿物组成、微观结构、安定性和胶凝性能进行了分析。结果表明,高温改性后的钢渣中出现了透辉石(CMS_(2))、镁铁尖晶石(MgFe_(2)O_(4))、钙铝黄长石(C_(2)AS)、铝酸三钙(C_(3)A)、磁铁矿(Fe_(3)O_(4))等新矿物相;高温处理促使钢渣中的FeO-MgO-MnO固熔体(RO相)分解,其中的FeO转化为Fe_(3)O_(4);钢渣的高温改性提升了钢渣的胶凝活性,有效地降低了钢渣中f-CaO和f-MgO的含量,当复合改性剂掺量为20%(质量分数,其中水库底泥与电石渣的质量比为3∶1)、处理温度为1150℃时,改性钢渣的28 d活性指数较原钢渣提高了12.2%,达到82.4%,符合GB/T 20491-2017《用于水泥和混凝土中的钢渣粉》中一级钢渣粉的活性指数(不低于80%)要求,原钢渣中f-CaO和f-MgO的质量分数分别降至1.21%和1.98%。

High-temperature modification using reservoir sediment and carbide slag was performed to study its influence on phase,structure and properties of steel slag.The physicochemical properties of raw materials,mineral constituents and microstructure of steel slag after the high-temperature modification were analyzed by X-ray fluorescence analyzer(XRF),X-ray diffraction(XRD),scanning electronic microscopy(SEM),energy dispersive spectrometry(EDS)and particle size analysis.It is found that new mineral phases such as diopside(CMS_(2)),ceylonite(MgFe_(2)O_(4)),gehlenite(C_(2)AS),tricalcium aluminate(C_(3)A)and magnetite(Fe_(3)O_(4))form in the modified steel slag.The high-temperature modification promotes the decomposition of RO phase in steel slag,in which FeO is converted to magnetite(Fe_(3)O_(4))simultaneously.The high temperature modification improves the cementitious reactivity of steel slag,and effectively reduces the dosage f-CaO and f-MgO in steel slag.When the dosage of composite modifier is 20%(m(reservoir sediment)∶m(carbide slag)=3∶1)and the treatment temperature is 1150℃,the 28 d activity index of modified steel slag is 12.2%higher than that of original steel slag,reaching 82.4%,which meets the technical requirements of GB/T 20491-2017‘steel slag powder used in cement and concrete’that the activity index of grade I steel slag powder is greater than or equal to 80%.The mass fraction of f-CaO and f-MgO in the original steel slag decreased to 1.21%and 1.98%respectively.