铁矿石溶解与烧结熔体流动行为机理

 在铁矿石烧结过程中,铁矿石部分溶解于烧结熔体,直接影响熔体的性质,进而影响烧结矿的黏结。为了明晰铁矿石与烧结熔体的相互作用,采用化学纯试剂煅烧法制备以Ca_3.6Fe_14.4O_25.2和CaFe₂O₄矿物为主的铁酸钙系黏附粉。以7种核心铁矿石-铁酸钙系(w(CaO)=15%)黏附粉构成烧结偶为主要研究对象,采用实验室烧结方法,研究了核矿石溶解与烧结熔体流动行为。在此基础上,使用化学纯试剂模拟核矿石的化学组成,考察了核矿石SiO₂、Al₂O₃含量对熔体横向流动面积和核矿石溶解指数的影响规律及机理。结果表明,在核矿石溶解于CaO-Fe₂O₃液相后,形成了交互层区域。核矿石中矿物,尤其是石英,溶解进入熔体,在靠近熔体一侧促使生成复杂CaO-Fe₂O₃系液相,而在靠近核矿石一侧促使简单CaO-Fe₂O₃系液相转变为CaO-Fe₂O₃-SiO₂系液相。靠近熔体一侧析出以铁酸钙系和赤铁矿为主的矿物,而靠近核矿石一侧析出以硅酸盐和赤铁矿为主的矿物。随着核矿石SiO₂含量的增加,一方面,使得溶解进入熔体中的SiO₂数量增加,溶解指数得到提升;另一方面,提升了简单CaO-Fe₂O₃系液相的黏度,从而使得熔体横向流动面积减小。随着核矿石Al₂O₃含量的增加,溶解进入熔体中的Al₂O₃数量增加,进而熔体横向流动面积降低,而核矿石溶解指数升高。Al₂O₃相较于SiO₂对核矿石溶解与熔体流动行为的影响更大。

Mechanism on behaviors of iron ore dissolution and sintering melt flow

During iron ore sintering, iron ores dissolve partially into sintering melt, which has a direct effect on the properties of melt, and hence the bonding of sinter. In order to clarify the interaction between iron ore and sintering melt, adhering fines of calcium ferrites existing in forms of Ca_3.6Fe_14.4O_25.2 and CaFe₂O₄ were prepared by calcination of chemical pure reagents. The behaviors of iron ore dissolution and sintering melt flow were studied through laboratory sintering method on the sintering couple composed of seven kinds of nuclei ore and adhering fines of calcium ferrites (w(CaO)=15%). Based on this, chemical compositions of nuclei ore were simulated using chemical pure reagents, and therefore the influence law of SiO₂ contents and Al₂O₃ contents in nuclei ore on horizontal flow area of melt and dissolution index of nuclei ore as well as its mechanism were explored. The results show that when nuclei ore dissolves into CaO-Fe₂O₃ system liquid phase, the interaction region is formed. After the minerals in iron ore, especially quartz, dissolves into the melt, complex CaO-Fe₂O₃ system liquid phase is formed at the area near the melt. At the same time, simple CaO-Fe₂O₃ system liquid phase is transformed into CaO-Fe₂O₃-SiO₂ system liquid phase at the area near nuclei ore. As the main minerals, calcium ferrites and hematite precipitate at the area near the melt, while silicates and hematite precipitate at the area near nuclei ore. With increasing of SiO₂ content in nuclei ore, on the one hand, the amount of SiO₂ dissolved into the melt increases, resulting in raising of dissolution index of nuclei ore. On the other hand, the viscosity of simple CaO-Fe₂O₃ system liquid phase is increased, resulting in reducing of horizontal flow area of melt. With increasing of Al₂O₃ content in nuclei ore, amount of Al₂O₃ dissolved into the melt increases, which decreases horizontal flow area of melt, but increases dissolution index of nuclei ore. Al₂O₃ in nuclei ore has stronger influence than SiO₂ on the behaviors of iron ore dissolution and sintering melt flow.