Theoretical And Experimental Research On Reduce Tailing Grade Of Iron Powder In Dry Magnetic Separation

As a large demand country for iron ore,China has rich reserves of iron ore resources,but most of them are "poor,miscellaneous,fine" refractory ore.With the development and utilization of mine resources,rich ore resources are decreasing,and the development and utilization of lean iron ore resources have gradually become the focus of the industry.At present,most of the mineral processing enterprises adopt "more crushing less grinding,grinding crushed generation" to reduce the grinding particle size to control the grinding cost,after efficient finely or more broken already part of the gangue dissociation products,through the primary threw gangue mineral in the ore in addition to as soon as possible,not only reduce the subsequent grinding amount,improve the feed grade,reduces the processing cost,also improve the utilization of iron ore resources.Therefore,it is of great practical significance and economic benefit to study the pretreatment and tail-throwing technology of fine grade lean iron ore.In order to realize the effective pre-separation of low-grade magnetite,the research group has developed a new type of dry-type magnetic separator,which is mainly composed of hopper,magnetic roller,guide plate,frame,speed regulating motor,ore separator and box body.The new magnetic separator adopts the design idea of integrated separation of multiple force fields.The air supply device is installed above the drum of each stage,so that the material particles are separated under the comprehensive action of gravity,magnetic force,and wind force,and the effect of magnetic agglomeration on the separation index is reduced.Based on the design principle of a new dry-type magnetic separator,a test prototype was produced.The pre-separation and tail-casting test of fine magnetite with a TFe grade of 13.51% and MFe grade of 3.98% were carried out in an iron ore concentrator in Inner Mongolia.The main purpose of the experiment is to reduce the inclusion of non-magnetic materials and improve the efficiency and index of dry preselection.Firstly,the influences of drum speed,magnet roller arrangement,wind speed,thickness of material layer,shape of guide plate and feed size on dry tailings of fine powder were explored through orthogonal experiments,and the primary and secondary relations of each factor affecting dry preselection tailings were determined.On the basis of the conclusion of orthogonal test,through roller speed test and magnetic roller arrangement test,an optimal matching method is obtained:when the rotating speed of the roller decreases gradually and magnetic field strength of the magnetic roller increases gradually,the pre-selection effect is the best.In the ore feeding grain size test,the relationship of tail-running index decreasing with ore feeding grain size was obtained.By changing the thickness of the material layer,the optimum treatment range of the material layer thickness of the test prototype was obtained.Aiming at the relationship between the wind speed of the air supply device and the sorting index,through the comparison tests of four different wind speeds,it is concluded that the air flow can intensify the movement of mineral particles in the sorting chamber,and has a certain positive effect on improving the grade of concentrate and reducing the grade of tailings.In the wind speed test,the air into the irregular separation chamber can increase the collision between particles,improve the degree of looseness of materials,reduce the agglomeration phenomenon,and the obtained separation index is better than that of the non-wind separation index.Under the optimal technological conditions,the grain size of the ore is-1mm,the rotating speed of the drum is 115r/min,the magnetic field arrangement is low,medium and high,the wind speed is 25m/s,the thickness of the material layer is 30mm,when combined with the irregular guide plate,the tail-casting effect is better,the content of MFe in the raw ore increases from 3.98%to 36.32%,and the tail-running can be controlled at 0.2%.This paper studies the way to reduce the dry separation rate of lean iron ore by experimental method.The results verify the feasibility and effectiveness of the idea of "combined wind-gravity and magnetic separation",which provides a new direction for the effective utilization of lean iron ore and has high theoretical and practical value for improving the utilization rate of lean iron ore.