| As is well known,China is abundant but lack of quality in iron ore resources.With the development of economy,it is urgent to rely on technological progress to maximize the use of iron ore resources.With the continuous deepening of mining,the disseminated particle size of ore gradually becomes smaller,and the grade of ore is gradually lower,which leads to the high cost of mineral processing.The optimum solution could be obtained by using energy-efficient equipment,and a preconcentration process with more broken less grinding.Aiming at the problem of high cost in separation of Anshan style lean hematite ores,a new technique of “the preconcentration process of mixed maghemite by high pressure grinding rolls and high intensity magnetic” was presented and investigated.In order to reduce production costs,improve resource recovery and utilization rate,and provide support for the upgrading of Anshan type lean hematite ores separation process,a beneficiation process was carried out on representative ore samples from Qidashan concentrator,so as to develop "the preconcentration process of mixed maghemite by high pressure grinding rolls and high intensity magnetic" suitable for the ore properties of Ansteel concentrator.The HPGR of GLGY0825 was used to crush mixed maghemite ore.The influence of different parameters of HPGR on product characteristics was studied from four aspects,such as roller surface pressure,roller speed,roll clearance and ore moisture content.The results show that when the roller surface pressure changes in the range of 9-11 MPa,the fine-grained content of the intermediate material product increases gradually with the increase of the pressure.When the roller speed is 0.335 ?0.419 M/s,with the increase of the speed,the fine-grained content of the intermediate material product gradually increases.When the water content of the ore increases from 0.8% to 3%,the fine-grained content of the intermediate material product gradually decreases.When the water content of the ore increases from 3% to 7%,the fine-grained content of the intermediate material product gradually decreases.With the increase of roller clearance,the fine content of the intermediate product decreases gradually when the roll gap is in the range of 12-20 mm.The magnetic induction intensity for 250 mT of 600×600 mm permanent magnet drum magnetic separator,the SLon-750 vertical loop pulsating high gradient magnetic primary was selected for the magnetic separation,the low intensity and high intensity magnetic preconcentration was carried out for the mixed magnetic-hematite ores by roller grinding.The results show that the TFe grade of raw material is 28.11%,and the particle size of crushed product is less than 3.5mm after being crushed by HPGR.After preconcentration with the low intensity and high intensity magnetic,the preconcentration concentrate was obtained with Fe grade of 34.04%,yield of 78.24%and recovery of 94.74%,with preconcentration tailings discarded by Fe grade of6.79%,yield of 21.76%.The feed grade was increased by 5.93%,which amount decreased by 21.76%,that improved the effiency of the mill.Whether the preconcentration concentrate by high pressure grinding rolls could fit the process,which(with the content of-0.074 mm was 65%)was separated by one-stage weak magnetic separation and one-stage high-intensity magnetic separation process.The magnetic separation mixed concentrate was grinded to 90% content of-0.074 mm by vertical mill,and the mixed oleic acid concentrate of magnetic separation was continued purified by anionic reverse flotation.The results show that the Fe grade of the concentrate is 67.85%,the yield is 32.31%,and the metal recovery rate of the concentrate is 77.98%.In conclusion the preconcentration concentrate by high pressure grinding rolls could fit the process well,with favorable results. |
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