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

Thanks to its complex composition and subtle disseminated extent,the specularite is a refractory 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 k A/m,a concentrate with Fe grade at 55.22% was obtained. The microscope analysis results indicated insufficient magnetite discrete which affecting the Fe grade of resulting concentrate. The phase analysis and microstructure of iron-bearing minerals 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 resulting magnetite mainly remained the texture of the original specularite,and the embedded characteristics and disseminated extent 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 magnetite was fine,all these had a significant effect on subsequent dissociation of magnetite.