镜铁矿磁化焙烧前后矿物组成与嵌布结构变化分析

The Mineral Composition and Disseminated Structure Change of Specularite in the Magnetic Roasting Process

镜铁矿因为矿物组成复杂、嵌布粒度细微,是一种难选矿,因此对其细粒粉矿,采用回转窑进行磁化焙烧—磁选试验研究。试验结果表明,原矿焙烧效果良好,在细磨至-0.074 mm占85%,磁选强度为144 k A/m的工艺条件下,磁选精矿的铁品位仅为55.22%,显微镜分析结果表明,磁铁矿未充分单体解离,影响精矿铁品位。通过分析焙烧过程中含铁矿物的物相及其微观结构,表明原矿经过磁化焙烧,菱铁矿、褐铁矿及其大多镜铁矿已经转变成磁铁矿,部分磁铁矿解离发育完全,颗粒疏松多孔。但大多数磁铁矿的矿石结构沿袭原矿中的镜铁矿,嵌布特征与嵌布粒度未发生明显变化,磁铁矿的矿石构造仍旧以粗粒条带状,稠密集与稀疏侵染状为主,并呈"不等粒"形式嵌布于脉石矿物之中,部分磁铁矿嵌布粒度较细,影响后续磨矿解离。

Thanks to its complex composition and subtle disseminated extent, the specularite is a refrac- tory iron ore. In this paper , a magnetic roasting experiment was implemented on specularite ore fines by a rotary kiln. The good roasting results had been achieved, and under the condition of grinding fineness （-0.074 mm） of about 85% and magnetic field intensity of 144 kA/m, a concentrate with Fe grade at 55.22% was obtained. The microscope analysis results indicated insufficient magnetite discrete which af- fecting the Fe grade of resulting concentrate. The phase analysis and microstructure of iron-bearing miner- als during the roasting ]process suggested that that after magnetic roasting the siderite, limonite and most of specularite had been converted to magnetite, and some magnetite was dissociative, however, the resul- ting magnetite mainly remained the texture of the original specularite, and the embedded characteristics and disseminated extenL was not changed significantly. The most magnetite had coarse band , dense and sparse infected structure, and unevenly embedded in gangue, while the disseminated extent of some mag- netite was fine, all the,;e had a significant effect on subsequent dissociation of magnetite.