Effect Of Plate Spacing On Particle Motion Behavior In Inclined Channel

In the process of gravity sedimentation,particles are mainly affected by density and particle size.Therefore,the overflow products of hydraulic separation equipment used in production,such as fluidized bed,will always be mixed with high ash fine mud,resulting in the ash content of concentrate exceeding the standard,while the underflow will lose some low-density coarse particles,resulting in a waste of tailings resources.This study summarizes the particle sorting law in the inclined channel by analyzing the movement and force of particles in the inclined channel.The research results are of great significance for the structural design of inclined plate channel,expanding the lower limit of gravity separation particle size and determining separation parameters.According to the separation model of particles in the inclined channel and the hydraulic variation law in the inclined channel,the boundary conditions based on particle Reynolds number and equipment structural parameters（plate length,plate spacing and inclination）,zcrit1and zcrit2,are established.The boundary conditions determine the relationship between particle properties and channel width,and define the application scope of particle sorting model.Around the verification of the effectiveness of the above two boundary conditions,verification tests such as characteristic spherical particle separation（single-phase test）,iron ore batch（particle group test）and continuous separation of coarse slime are set up.The single-phase characteristic spherical particle separation test（part of the test process）obtains the channel separation model with close particle separation by obtaining the actual channel separation water velocity when the particles reach the overflow at exactly uniform speed and the relative error value of the channel water velocity predicted by each separation model.The experimental results show that when Zcrit1>Z and Zcrit2>Z,the particles are located on the plate surface and the channel belongs to narrow channel,which is suitable for predicting the separation water velocity of particle channel by using the weakened particle size model;When Zcrit1>Z and Zcrit2<Z,the channel belongs to narrow channel,which is suitable for predicting the separation water velocity of particle channel by equilibrium model;When Zcrit1<Z,the channel belongs to wide channel,and the empirical model is used to predict the separation water velocity of particle channel.It is verified that the boundary conditions are effective in the ideal sorting environment.Expand from single-phase environment to particle group environment,carry out iron ore batch experiment,obtain d₅₀particles of water velocity in each channel,or d₅₀critical separation water velocity and the relative error value of channel predicted by song separation model,and obtain the channel separation model with close separation of d50 particles.The test results show that there is a boundary particle size d=0.13mm in the separation process,and the actual channel separation water velocity of iron ore particles on both sides of the boundary particle size will be close to the channel water velocity predicted by different separation models.When d>0.13mm,the error between the actual water velocity and the equilibrium model is less than 10%,and the particles migrate.At this time,Zcrit1>2mm and Zcrit2>2mm;d<0.13mm,the actual water velocity and weakened particle size model predict that the channel water velocity is less than 10%,and the particles do not migrate.At this time,Zcrit1>2mm and Zcrit2<2mm.The batch test of iron ore verifies that the particle group will not affect the effectiveness of boundary conditions.The continuous separation verification test of coarse slime is carried out to verify that changing the separation parameters（plate spacing,supplementary water and feed concentration）will not affect the effectiveness of boundary conditions.The continuous separation test shows that the smaller the distance between the channel plates,the lower the ash value generated by overflow,with a minimum of 9.8%,which is far less than the minimum ash content of float and sink clean coal,10.67%.Too high feed concentration will destroy the stable separation environment;Proper water addition can effectively improve the separation effect of coarse particles with low density,but its effect of reducing ash is limited.The continuous separation overflow ash yield is very close to the float sink curve,indicating that the separation process is based on density separation.At the same time,the error between the predicted channel water velocity and the actual channel water velocity by the weakening particle size model of overflow products in six groups of continuous sorting tests is less than 10%.At this time,the boundary condition Zcrit1=1.5mm,less than 2mm.This thsis has 55 figures,46 tables and 92 references.