CO/CO_2气氛下赤铁矿向磁铁矿的流化床还原转变

Reductive Transformation of Hematite to Magnetite with CO/CO_2 Under Fluidized Bed Conditions

采用纯矿物试验、等温还原法和微观结构分析法研究了赤铁矿向磁铁矿流化床还原转变行为及动力学.动力学研究表明,以20%CO和80%CO_2(质量分数)混合气体为还原流化剂、微型流化床为反应器,在还原温度为773～873 K时,赤铁矿向磁铁矿的选择性还原转化受磁铁矿晶核的形成和一维生长A3/2模型控制,反应的表观活化能ΔEa为49.64 k J/mol,指前因子A为6.55 s-1.BET比表面分析及扫描电镜测试结果表明,新生磁铁矿晶核呈致密针状结构,且长度不一;随着反应的进行,针状结构晶核增多并聚集形成多孔状的磁铁矿颗粒.

The reductive transformation behavior and kinetics of hematite to magnetite under fluidized bed conditions were studied by single mineral roasting test,isothermal reduction method and microstructure analysis.The results of reaction kinetics show that the selective reduction of hematite to magnetite with reductive fluidizing agent of 20wt% CO-80wt% CO2 in a micro-fluidized bed reactor at 773-873 K is controlled by formation of magnetite crystal nucleus and one-dimensional growth(A3/2 model),the apparent activation energy ΔEa of the reaction is 49.64 kJ/mol and the pre-exponential factor A is 6.55 s^-1.The results of BET specific surface analysis and scanning electron microscopy measurement show that the fresh magnetite nucleus are dense needle-like structure with different lengths,and that as the reaction proceeds,the magnetite nucleus with the needle-like structure increases and aggregates to form porous magnetite particles.