还原铁法重构钢渣及其矿物组成

Steel Slag Reconstruction Experiment by Reduction FeO_x and Its Mineral Composition

分别采用直接还原法和熔融还原法对柳钢和宝钢2种钢渣进行了铁还原重构试验,利用X射线衍射、扫描电子显微镜研究了重构钢渣的矿物组成,并采用水泥胶砂强度试验法测定重构钢渣的活性指数。结果表明:直接还原法可将钢渣中铁氧化物还原成铁珠,尺寸范围为1～50μm,金属铁颗粒均匀分布在各种矿物之间;铁酸钙相、镁蔷薇辉石在重构过程中分解,柳钢钢渣硅酸三钙(C3S)和宝钢钢渣硅酸二钙(C2S)分解,钢渣重构后硅酸钙相组成由原钢渣中Ca/Si摩尔比决定;RO相被还原成金属铁和MgO,原钢渣总铁含量越高,铁还原越彻底。熔融还原法可将钢渣中铁氧化物还原成金属Fe,在重力作用下渣铁分离,还原率近乎100%;随炉冷却渣矿物组成为钙铝黄长石、镁黄长石、C2S,与硬矿渣相似;水淬渣以玻璃体为主,柳钢和宝钢重构渣玻璃体含量分别为97%和73%,与水淬矿渣组成相近。采用还原铁法所得重构钢渣的活性指数显著提高。

Two steel slags from Liuzhou and Baoshan were reconstructed via reduction of FeOx. The experiments for direct reduction and melting reduction were carried out, respectively. The mineral composition of modified slag was analyzed by X-ray diffraction （XRD） and scanning electron microscope （SEM）. The activity index of modified slag was determinated by a mortar strength testing method. The results show that iron oxide of the steel slag can be reduced into iron shot in the size range from 1 to 50 μm when direct reduction is used, and the metallic iron particles are evenly distributed between minerals. The calcium ferrite phase, the manganolite, tricalcium silicate （C3S） of steel slag from Liuzhou, dicalcium silicate （C2S） of steel slag from Baoshan decompose in the modifica- tion process. The composition of calcium silicate phase after modification depends on the molar ratio of Ca/Si in the steel slag from Liuzhou. The RO phase is reduced into metallic iron and MgO. The higher the percentage of iron element in the steel slag from Liuzhou, the greater the reduction ratio will be. Moreover, the iron oxide in the steel slag can be reduced into Fe by melting reduction as Fe separates with slag by gravity, and the degree of reduction can reach 100%. Gehlenite, akermanite and dicalcium silicate are the constituents of modified slag by furnace cooling, which is similar to the hard slag. The content of vitreum in modified slag by wa- ter-granulating of the both steel slags is 97% and 73%, respectively, which is similar to the water-granulated slag. The activity index of modified slag increases significantly due to the reduction.