Study On Granulation-Magnetic Roasting With Rotary Kiln-Magnetic Separation Of Fine Specularite

Fine specularite from JISCO has complex mineral composition and dissemination relationship.It is difficult to use conventional concentration process to treat effectively.Magnetic roasting is the most effective method to deal with such fine ore at present,and magnetic roasting with rotary kiln is reasonable.But the fine ore,especially the 0~1 mm,cannot access to rotary kiln directly while the grinding and pelletizing may cause the grade lower,process more complex and cost higher,the application is limited.In this paper,combined with the characteristics of such fine ore,granulation and magnetic roasting with rotary kiln process is used to simplify the process and reduce costs and obtain a good beneficiation indexes at the same time.Then the roasting and sorting process factors which would have an influence on the grade of concentrate have been studied.The main iron minerals of fine specularite are specularite,siderite and limonite,and the gangue minerals are mainly quartz,jasper and ankerite.The mineral composition and disseminated relationship of the fine specularite is complex,because the iron minerals' fine disseminated extent and part of the gangue mineral contain iron.It is difficult to separate by conventional concentration process.Under the condition of 1.2 wt% bentonite and 8 wt% water and granulation for 10 minutes,the size of granulation is 3~5 mm.After drying,under the condition of 20% filling rate and 2.5 wt%,roasting at 750 °C for 60 minutes can obtain a good ore dressing indexes,the grade of iron is 53.01% and the recovery is 87.66%.Analyzing the process of roasting combined with the XRD analysis,verifying the roasting temperature is reasonable.Roasting process changed the iron phase and mineral structure,but didn't change its dissemination.The 0~1 mm fraction of granulation increased only 6.78%,so the pulverization rate is low.The effect of magnetic roasting of ? 0.65-0.45×9 m variable diameter rotary kiln is the best.The roasted ore roasted by variable diameter rotary kiln under a optimal conditions was used for magnetic separation process test,after one stage of roughing,one stage of scavenging and one stage of concentration,a good ore dressing indexes was obtained which the iron grade is 56.16% and iron recovery is 85.84%.The analysis suggests that gangue minerals such as jasper,and magnetite reduced by siderite affects the grade of concentrate,which is difficult to promote through improving monomer dissociation degree by grinding.The granulation-magnetic roasting with rotary kiln-magnetic separation process promotes the efficiency of the use of fine specularite,what's more,getting a good economical benefit,which provides a reference for use of this kind of fine ore.