The Effect Of Feed Pressure And Feed Properties On Separation Efficiency Of Three-cone Hydrocyclone

Since the first application of hydrocyclone in concentrator in 1939,it has been widely promoted and improved because of its compact structure,low operation cost and no need to add medium.Three-cone cyclone is a new type of separation equipment which can efficiently separate coarse coal slime according to its density on the basis of traditional hydrocyclone.Although the three-cone hydrocyclone has been widely used,the separation mechanism of the three-cone hydrocyclone is still not perfect.In this paper,the three-cone hydrocyclone is taken as the research object.from the aspects of laboratory experiments to explore the influence of different feed pressure and feed characteristics on the separation effect of three-cone hydrocyclone,and the feed pressure from numerical simulation in this paper for velocity field and pressure field in the cyclone,the influence of the air column and into the material properties for the influence of the swirler medium density field,in order to further explore the three-cone hydrocyclone separation mechanism.The experiment of coarse coal slime separation with three-cone hydrocyclone was designed for a coal preparation plant in Xinwen.The optimum structure parameters were determined as follows:new cone,100 mm height of cylinder,40 mm diameter of overflow pipe and 50 mm insertion depth.Laboratory tests show that for pressure,with the increase of feeding pressure,the ash content of overflow+0.2mm of Three-cone cyclone shows the same change trend as the yield,which increases sharply at first,decreases slowly and then rises again.The effect of low pressure on the yield and ash content of overflow+0.2mm of Three-cone cyclone is greater than that of high pressure,and the overpressure destroys the separation bed layer and reduces the separation rate.The effect also increases energy consumption and equipment wear.In order to explore the effect of fine particles in the selected coal slime on the sorting effect,this paper designs single factor experiment to investigate the effect of four-grain particle pairing of 0.2-0.125mm,0.125-0.09mm,0.09-0.045mm and-0.045mm.The effect of the experiment:the finer the particle size of the fine particles in the coarse coal slime,the lower the overflow of the cyclone+0.2mm ash,the lower the yield;the coarser the particle size,the higher the ash content of the overflow+0.2mm,The higher the yield.For the content of fine particles in the selected coarse coal slime,the more the fine grain content in the selected coarse coal slime,the higher the ash content of the overflow+0.2 mm,the higher the yield;the smaller the fine particle content,the ash content of the overflow+0.2 mm The lower the yield,the smaller the yield.The post-flow analysis of the overflow and underflow corresponding to different fine particle size and content was carried out.The Ep value was used as the criterion for evaluating the sorting effect.It was found that the Ep value gradually increased with the increase of fine particle size,and the Ep value changed interval.It is 0.215-0.115.As the content of fine particles increases,the Ep value decreases gradually,and the Ep value varies from 0.215 to 0.07.It shows that the fine particles in the selected slime act as the sorting medium,and the sorting medium in the three-cone hydrocyclone is the result of the fine-grain interaction of each fraction.Reasonable fine particle size and fine content can improve the sorting effect of the three-cone hydrocycloneThe VOF model is used to simulate the gas-liquid two-phase flow field in a three-cone hydrocyclone by fluent software,and the Mixture model is used to simulate the gas-liquid-solid three-phase flow field.The distributions of tangential,radial and axial velocity and pressure fields were investigated by simulating the gas-liquid two-phase clear water flow field,and the formation process of air column was explored.The influence of different feed pressures on the velocity and pressure flow fields was also explored.Through the simulation of gas-liquid-solid three-phase flow field,the distribution of density field in a three-cone hydrocyclone and the influence of different particle size and content of fine particles on the distribution of density field were investigated.The simulation results show that the distribution of tangential velocity,radial velocity and axial velocity in the cyclone has certain regularity,and the three-dimensional velocity is symmetrical in the radial direction.The tangential velocity from the axis to the wall first increases sharply,then slowly decreases,then sharply decreases;the axial velocity increases from the axis to the wall with a negative value to a positive value;the radial velocity...The change of feeding pressure does not affect the distribution of three-dimensional velocity,but it will change the size of three-dimensional velocity;with the increase of feeding speed,the three-dimensional velocity will increase;with the increase of feeding pressure,the air column will become larger,and the formation time will become shorter.For the simulation of the density field in a three-cone hydrocyclone,it is found that the finer the particle size,the lower the density field formed,the lower the content of the fine particles,and the lower the density field formed.After the flow field simulation of the three-cone hydrocyclone is completed,DPM model is used to simulate the separation process of particles in the three-cone hydrocyclone.Five kinds of particles with different densities,1 350 g/cm3,1 450 g/cm3,1 550 g/cm3,1 650 g/cm3,1 750 g/cm3 and 1 750 g/cm3,were used in this paper.The effect of density on the movement of particles in a three-cone hydrocyclone was investigated qualitatively.Through the simulation of particles,it is found that the trajectory and separation time of particles with different densities are different in the three-cone hydrocyclone.The separation time of particles with intermediate densities is longer in the three-cone hydrocyclone,and the separation time of high densities is shorter.Through the analysis of particle trajectory,it is found that particle sorting is carried out in the same density band as its own density level.