Magnetic Roasting With Microwave Process And Mechanism Of Fine Specularite

As the main raw material of JSCO, the Jingtieshan mirror iron ore was hard toseparate for its complex mineral composition, uneven disseminated grain size, lowpurity mineral particles and the similar physical parameters of iron minerals and gangue,such as susceptibility or density. Currenttly, research showed that magnetic roasting is aeffective method to deal with this kind of red iron. However, there still exist somelimitations of conventional magnetic roasting process. Recently the microwave heatingmethod was effective applied to iron ore carbothermic reduction for its uniqueadvantages:①the "half-cooked" phenomenon in roasting process could be reduced forits rapid homogeneous heating.②the crazes between absorbing metallic minerals andgangue minerals could be produced easily for its selective heating which help forgas-solid reducting reaction and can decrease grinding energy.③the process could besimplified for the powder ore can be roasted in microwave directly. Thus it is importantto study the magnetic roasting with microwave process on this kind of specularite.In this paper, the magnetic roasting with microwave and low intensity magneticseparation experiment of Specularite was studied and the parameters of the magneticroasting with microwave was determined. Then the mechanism of microwave heatingwas studied from the perspective of mineral structure changes.Result showed that, the optimal operation conditions were as followed: carbonpowder content was2.5%, microwave power was1000W, roasting temperature was550℃, roasting time was15min, grinding fineness was-0.074mm about85%, andmagnetic field intensity was92.16kA/m, with these conditions the iron grade couldreach55.16%and the recovery could reach86.65%.During the magnetic roasting with microwave, the specularite, siderite andlimonite in the fine grained specularite was converted to magnetite, the effect of themagnetic roasting with microwave was obvious. And there were many cracks caused inthis process, but the cracks that generated in different iron ore were different. Themagnetite transformed from specularite could generated fewer cracks, and the crackswere mainly produced between iron ore and gangue or just in gangue, The magnetitetransformed from siderite could generated cracks from internal, which result in looserore structure. Compared with conventional heating, the microwave heating could promote thegeneration of cracks, reduce the grinding energy consumption and accelerate thedissociation of aims and gangue minerals, which was help for magnetic separation.