微波加热含碳铁矿粉还原矿相结构研究

Metallography of iron coal containing ore concentrates reduced by microwave heating

微波加热含碳铁矿粉还原矿相结构分为金属铁、浮氏体和渣相结构。矿粉颗粒围绕煤粉颗粒进行还原,形成星点状金属铁,进而形成环带状结构。由于矿-煤颗粒界面间还原出的金属铁厚度增大,使初始直接还原反应减弱,尚未还原的FeO核心依靠碳气化生成的CO和金属铁中碳的扩散继续还原,形成蠕虫状金属铁连晶结构。浮氏体对微波具有一定的吸收性,在微波场中自身热碎裂,可加速碳热还原。渣相含有变价铁元素,对微波有一定的吸收能力,有利于渣相中复杂铁氧化物的还原。

Microstructures of coal containing iron ore concentrates reduced by microwave heating are classified as the metal iron microstructure, the wustite microstructure and the slag phase microstructure. The self-reduction process of iron ore concentrates containing coal heated by microwave was that magnetite grains were initially reduced around coal grains to form metal iron granular structure, then jointed together to form metal iron semi-annular structure, annular structure and cincture structure. Being accompanied by development of reduction reaction, the reduced metal irons increased between coal grains and magnetite grains, which obstructed the interface of direct reduction reaction. The core of FeO was sequentially reduced by CO and C diffusion in the metal iron, eventually the vermiform iron-jointed crystal texture was formed. Wustite possessed the absorbency of microwave to a certain degree and might be broken up itself in microwave field, which was helpful to carbothermic reduction. Slag also possessed the absorbency of microwave because its component is very complicated,and propitious to the reduction of its complex iron oxide.