酒钢镜铁矿磁化焙烧—磁选精矿中镁和锰含量偏高的原因分析

Causes Analysis of High Mg and Mn Content in Concentrate of Magnetic Roasting and Magnetic Separation With JISCO Specularite

酒钢镜铁山式镜铁矿矿物组成复杂,嵌布粒度细微,是一种难选的红铁矿,磁化焙烧—磁选是其较好的分选方法。但生产及研究发现,磁化焙烧—磁选精矿中Mg、Mn含量偏高,降低了其含铁品位。为查明原因,对原矿、焙烧矿、磁选精矿及尾矿进行了详细的微观分析。分析结果表明,原矿中的Mg、Mn元素主要存在于褐铁矿、菱铁矿及其铁白云石之中,极少分布于镜铁矿中;经磁化焙烧之后,大多镜铁矿已经转变成磁铁矿,而菱铁矿、褐铁矿与铁白云石受热分解,生成强磁性的镁、锰、铁尖晶石矿物,因此造成铁精矿中的Mg、Mn元素含量偏高。

JingTie Shan type specularite of JISCO （Jiuquan Iron＆Steel Co. ） is a refractory red iron ore because of its complex composition and subtle dissemination. The process of magnetic roasting and magnetic separation is a feasible method for its beneficiation. But the results of production practice and research showed that the Mn and Mg elements were enriched in concentrate, which had effect on the Fe grade of concentrate. In order to find the causes of the problem, microscopic analysis in detail was proceeded with undressed ore, roasting ore, magnetic concentrate and tail-ings. The analysis results showed that Mg and Mn elements were mainly found in siderite, limonite and ankerite, but rarely found in specularite. Most of specularite was converted to magnetite, while siderite, limonite and ankerite were converted to spinel mineral, which contained Mg and Mn ele-ments after magnetic roasting. And the spinel mineral became the concentrate with magnetite after magnetic separation, which was the major reason for the high content of Mn and Mg in concentrate.