鞍山某难选混合铁矿石预富集精矿磁化焙烧过程物相转变研究

基于流态化焙烧手段，对鞍山某含菱铁矿难选混合铁矿预富集精矿的磁化焙烧过程物相转变行为进行了研究。参照工业还原气条件的直接磁化焙烧结果显示，预富集精矿中的菱铁矿会产出弱磁FeO，降低磁化率。采用氧化—还原的工艺，可以将菱铁矿改性为弱磁赤铁矿α-Fe₂O₃和磁赤铁矿γ-Fe₂O₃，避免分解产物FeO存在。但后续500~550 ℃长时间还原仍会出现弱磁FeO，只有在还原温度450 ℃磁赤铁矿γ-Fe₂O₃的还原产物Fe₃O₄能够稳定存在。据此提出了“低温预氧化—超低温还原”磁化焙烧工艺，能够实现含菱铁矿混合难选铁矿的稳定磁性转化，且满足生产适应性需求。经该流态化工艺磁化焙烧后，预富集精矿焙烧矿经弱磁选可达到铁精矿产品铁品位65.15%、铁回收率92.02%的良好指标。实验结果为含菱铁矿混合难选铁矿的磁化焙烧生产工艺开发提供了参考依据。

Research on the Phase Transformation of Anshan Refractory Mixed Iron Ore Preconcentrate in the Magnetization Roasting Process

Based on the fluidized roasting method,the phase transformation of Anshan preconcentration refractory iron ore containing siderite in the magnetization roasting process was researched.With the reducing condition,simulating the industrial reduction gas composition,siderite in the refractory iron ore generated weak magnetism FeO.Through the oxidationreduction way,the siderite can be modified to weak magnetic α-Fe2O3 and strong magnetic γ-Fe2O3 firstly,and FeO was avoided in decomposition reaction.But FeO was still generated in the following 500~550℃reduction.Only at the experiment reduction temperature 450℃,the reduction product Fe3O4 from γ-Fe2O3 is stable existence.According to the experimental results,a new magnetization roasting process“low temperature oxidation-ultralow temperature reduction”was built,which can achieve the stable magnetic transformation of refractory iron ore containing siderite and meet requirement of practical production adaptability.By the new magnetization roasting process and low intensity magnetic separation,the roastedore of the Anshan preconcentration ore can achieve iron concentrate TFe containing 65.15%and recovery of 92.02%.The results provided a new way for the efficient utilization of siderite-bearing refractory iron ore.