赤铁矿石隧道窑直接还原助还原剂的作用及机理

Function and mechanism of assistant reducers in iron recovery by the direct reduction in tunnel kilns of hematite

对隧道窑直接还原焙烧--磁选法处理低品位难选赤铁矿石进行了探讨,重点研究助还原剂NCP的作用及机理.以煤作还原剂,质量分数为20%,CCO和NCP为助还原剂,质量分数分别为15%和5%,在焙烧温度为1200℃,焙烧时间为8 h的条件下,可以得到铁品位92.61%、铁回收率92.38%的铁精矿.利用X射线衍射和扫描电镜对助还原剂NCP的作用机理进行分析.结果表明NCP可以与原矿中石英发生反应,生成硅钠石和钠长石,破坏原矿结构,使还原性气体更易与赤铁矿接触发生还原反应生成金属铁.

Iron enrichment from refractory low-grade hematite was studied by using the method of direct reduction roasting in a tunnel kiln and magnetic separation. This study focused on the function and the mechanism of the assistant reducer NCP. Under the condi- tions of coal as the reducer with a mass fraction of 20% , CCO and NCP as the assistant reducers with mass fractions of 15% and 5% respectively, and roasting at 1 200 ℃for 8 h, a concentrate of the Fe grade of 92.61% with the Fe recovery of 92.38% can be pro- duced. The mechanisms of NCP were also investigated by X-ray diffraction and scanning electron microscopy. It is shown that NCP can react with quartz in the raw ore and generate natrosilite and albite, which can destroy the structure of the raw ore and induce a reaction between reducing gas and hematite to create Fe.