鲕状赤铁矿深度还原物相及结构的演化规律

为了研究深度还原过程中鲕状赤铁矿石物相及结构的演化规律,采用X射线衍射(XRD)和扫描电子显微镜(SEM)考察了不同还原阶段还原样品的物相转化和微观结构变化,并建立了相应的深度还原机理和微观结构演化模型。结果表明,鲕状赤铁矿石深度还原过程中铁矿物按照Fe_2O_3→Fe_3O_4→FeO(Fe_2SiO_4,FeAl_2O_4)→Fe的顺序还原为金属铁,杂质组分则主要依据Fe-Al-Si-O→Fe-Ca-Al-Si-O→Ca-Al-Si-O的历程形成渣相;矿石鲕状结构按照由鲕粒边缘至鲕粒内部的空间顺序逐渐发生破坏,矿石微观结构演变过程可以分为边缘破坏、内部破坏、完全破坏3个阶段;金属相及渣相的形成与聚集生长是矿石微观结构破坏的直接动力。

Evolution law of phase and structure of oolitic hematite ore in coal- based reduction

In order to study the evolution law of the phase and microstructure of oolitic hematite ore during the coal- based reduction, the phase transformation and microstructure change of the reduced samples at different reduction stages were investigated by X- ray diffraction （XRD） and scanning electron microscopy （SEM）, and the corresponding mechanism models of reduction process and microstructure evolution were established. The results show that the iron minerals are reduced to metallic iron in the order of Fe2O3→Fe3O4→FeO (Fe2SiO4, FeAl2O4)→Fe, and the impurity components follow the course of Fe- Al- Si- O→Fe- Ca- Al- Si- O→Ca- Al- Si- O to form slag phase. The oolitic texture of iron ore is gradually destroyed according to the spatial order from the edge to the interior of ooids. The process of microstructure evolution can be categorized into three stages：edge break, internal damage and complete destruction. The formation and aggregation growth of metal phase and slag phase are the direct driving force for the destruction of the ore microstructure.