铬铁矿的还原焙烧与磁选分离

Reduction roasting and magnetic separation of chromite ore

以南非铬铁矿为原料,以潞安煤粉为还原剂,进行了铬铁矿粉还原焙烧与磁选分离实验。借助扫描电镜、能谱分析和X射线衍射分析,对碳热还原和磁选分离过程中的物相变化进行了系统研究。实验发现,当温度低于1 200℃时,铬铁矿仅发生少量铁氧化物的还原,当温度高于1 300℃时,铬铁矿中铬氧化物开始被还原成碳化铬。随着还原反应的不断进行,铬铁尖晶石结构逐渐发生转变并被破坏。在本实验条件下,铬铁矿较为适宜的预处理温度为1 200℃,此温度下的还原产物磁选后,磁选产物几乎全部为金属铁,磁选所得尾渣的除铁率为46%,铬的收得率为80%,w(Cr2O3)/w(ΣFe O)值高达3.75。研究工作对于铬铁矿预处理工艺的设计开发及低品位铬铁矿的综合利用具有理论指导意义。

Reduction roasting and magnetic separation of chromite ore is investigated, using South African chromite ore as raw materials and Lu＇ an pulverized coal as reductant.The phase changes in the reduction and magnetic separation process is analyzed systematically by means of SEM-EDS and X ray diffraction.The results show that only iron oxides in the chromite ore are reduced when the temperature is below 1 200 ℃, and chromium oxides are reduced into chromium carbide when the temperature exceeds 1 300 ℃.The spinel structure is transformed and destroyed gradually with the proceeding of reduction reaction. Under the considering experimental conditions,the appropriate temperature for pretreatment is 1 200 ℃ ,with an iron removal rate of 46%,a chromium yield rate of 80% ,and a higher ,w（Cr2O3）/w（ΣFe O）value of 3.75,the magnetic separation product is mainly iron.This work has great theoretical significance for the development of chromite ore pretreatment process and the comprehensive utilization of low-grade chromite ore.