Research On Dynamic Capture Characteristics Of Rotating Magnetic Media

High gradient magnetic separation?HGMS?has been widely used to separate weakly magnetic ores such as oxidized iron ore,ilmenite and wolframite ores,and it is also applied to purify non-metallic ores such as quartz and feldspar.This method has such characteristics as high separation efficiency,low energy consumption and large capacity.However,it has a relatively low selectivity,which was not solved until today.Therefore,it has theoretical value and practical significance to explore and develop a new HGMS method with a higher selectivity.Centrifugal HGMS is a new separation method based on a new composite force field-centrifugal high gradient magnetic field,which has the advantages of high separation selectivity and strong capture efficiency.The magnetic capture using a rotating matrix is the major feature that differs this new method from the conventional HGMS methods,so that the research on the capture characteristics of rotating matrix has an important value to fully understand the mechanism of centrifugal HGMS and to develop new CHGMS technologies and separators.In order to investigate the capture characteristics of the rotating matrix,a rotating matrix capture analysis device?MCA90?is developed.It mainly consists of stander,magnetic system,separation tube,driving devices and matrix.And the results of magnetic field measurement and theoretical analysis show that:?1?the average magnetic field intensity in the separation area of two-pole and four-pole magnetic systems is 0.5T and 0.3T,respectively,and they are regular distribution,and the simulation results show that the two-pole is better than the four-pole.?2?Magnetic particles are mainly subjected to magnetic force,centrifugal force,fluid resistance and friction force in the process of separation.The rotational speed of the magnetic matrix decide the flow state of the pulp in the separation area,and ultimately decide the fluid resistance.?3?The rotation of magnetic matrix has a function of stirring and loosening on mineral particles,and in the process of matrix rotation capture,there is“magnetic roll”phenomenon about the mineral particles adsorbed on the matrix.They all can efficiently improve the selectivity of the separation process,so that improve the grade of concentrate.The main factors that affect the capture characteristics of matrix include rotational speed of matrix,feeding capacity,matrix wire diameter,rotational mode and speed of rinsing water.?4?During the capture process of magnetic matrix,a“magnetic rollover”would be generated on the captured magnetic particles,which is helpful to the release of the entrained gangue minerals,leading to improve the quality of concentrate products.The capture characteristics of rotating matrix are investigated with the raw ores and their concentrates of ilmenite and hematite,and it is found that:?1?For the concentrate,when the rinsing water,matrix diameter and rotational speed of matrix are 20cm/min,6mm and 180r/min,respectively;the revolution capture of single wire tend to saturate exceeding 45g,after which the capture mass is basically invariable.The capture of large diameter is large than that of small ones.The rotational speed and model of the matrix have significant influences for the capture process,and the capture mass decreases as the rotating speed increases.The auto-rotation has a greater capture mass than that of the revolution under the same conditions.In addition,the rinsing water improves the capture of concentrate,but the capture mass declines when the speed of rinsing water is too large.?2?The ilmenite concentrate is screened into four grain sizes of-0.15+0.1mm,-0.1+0.074mm,-0.074+0.046mm and-0.046mm,and they are used for capture experiments;the capture results show that:for the-0.074+0.046 mm particles,the capture mass is the largest in the four grain sizes,and then is for the-0.15+0.1mm.?3?The capture results of ilmenite ore show that,under the optimal conditions,the capture mass of an auto-rotating wire is 0.7g,and the TiO₂grade of capture product reaches 26.78%.The capture mass of revolution matrix is0.27g,with TiO₂ grade reaching 32.80%.?4?The capture results of hematite ore show that,under the optimal conditions,the capture mass of auto-rotating matrix is 1.02g,and the Fe grade of capture product is 39.24%.The capture mass of revolution matrix is 0.91g,with Fe grade reaching 46.35%.In conclusion,the rotation of matrix can significantly improve the separation selectivity of HGMS process and greatly improve its separation performance.The results achieved from this research would help reveal the separation mechanism of centrifugal HGMS method,and develop new centrifugal HGMS separators.