石灰重构钢渣过程中的物相变化

Phase Change of Steel Slag During Reconstruction by Lime

以石灰作为单一调节材料高温重构钢渣,利用X射线衍射、岩相分析、扫描电子显微镜研究了重构过程中钢渣的矿物组成及RO相的变化,并测定了重构钢渣的安定性和活性指数.结果表明:RO相在CaO作用下优先发生分解反应,其中的FeO随CaO掺量增加依次生成Fe3O4、CF(铁酸一钙)、C2F(铁酸二钙)及Ca2(AlFe)O5(铁铝酸钙)、C4AF(铁铝酸四钙),其中的MgO部分以MgO晶体存在,部分固溶在硅酸盐相和液相中;当CaO/SiO_2摩尔比不够大时,原钢渣中的C3S(硅酸三钙)在重构过程中分解成C2S(硅酸二钙);由于CaO优先与含量较高的铁元素反应,CaO/SiO2摩尔比达到3时仍没有C3S生成,只有当与铁反应完全后多余的CaO才会与C2S反应生成C3S;石灰重构钢渣不会产生安定性不良且胶凝活性明显提高.

Steel slag was reconstructed by using lime as the single controlling material at a high temperature, and XRD, petrographic analysis and SEM techniques were adopted to determine the mineral composition of the modified steel slag as well as the transformation of the RO phase in the modification process. Moreover, the stability and the activity index of the modified steel slag were tested. The results demonstrate that （ 1 ） the RO phase primarily reacts with CaO, in which FeO phase is decomposed into Fe304, CF （calcium ferrite）, CEF （dicalcium ferrite）, Ca2 （AWe）05 and C4AF （tetraealeium alumino-ferrite） successively with the increase of CaO content, and a part of MgO phase exists in the form of MgO crystal, and the others behave as the solid solution in the silicate and liquid phases; （2） when the CaO/SiO2 mole ratio is not large enough, C3S （tricalcium silicate） in the original steel slag is resolved into C2S （dicalcium silicate） in the modification process; （3） no C3S generates even when the CaO/SiO2 mole ratio reaches 3 because CaO primarily reacts with high-content iron; （4） only when the iron reacts completely, may the redundant CaO react with C2 S to produce Ca S; and （5） both the stability and the cementitious activity of the steel slag significantly improve after the modification by lime.