Studies On The Combination Hydrocyclone Based On Separation And Classification

At present most coal preparation plants have increased the coarse slime recovery or separation.But the separation process is long,and the separating effect of the spiral separator is poor.Therefore,based on the concept of multi overflow pipe cyclone and combined with the study on Cyclone Column Separator,a new type of separating and classifying cyclone system device was designed,incluiding separating and classifying cyclone device with no-magnification overflow shunting and magnification overflow shunting,which consists of side overflow separation and classification and through just one feed can achieve the goal of discharging stones from the underflow of the first section,fine coal from the underflow of the second section and fine mud from overflow of the first section as well as the second section together at the same time.The fine material after the first stage of the overflow flows directly from the upper overflow pipe,the coarse material flows from the side of the overflow outlet along the tangent line into the second section of the cyclone for again grading.And two different connection methods connecting the first stage cyclone upright and inverted with the second cyclone on direct overflow connected cyclone device are proposed respectively.Taking the-3mm coal slime of Majialiang coal preparation plant as the research object,two different cyclone devices studies were tested respectively.Regarding the separating and classifying cyclone device with no-magnification overflow shunting,the insertion depth of overflow pipe,diameter of overflow pipe,underflow diameter,side overflow connection caliber and feed pressure studies were tested respectively.The results show that,side overflow connection caliber have significant effects on the first stage classification and separation and the second stage classification of the device.The ash of two underflow increased significantly with the increase of cross-sectional area,the coarse size of first overflow decreased and classification performance got better.But large connection caliber will cause the ash higher of the second underflow and decrease the classification performance of the second stage cyclone.The insertion depth of overflow pipe and diameter of overflow pipe have significant effects on the first stage classification and separation of the device,and have no obvious influence on the performance of second classification.To ensure the effect of separation and classification of the device.To achieve the purpose of first overflow discharging high ash fine mud as well as controling overflow running coarse size,depth of the overflow pipe should not be more than the depth of the sleeve.A large overflow pipe diameter can also lead to running coarse size of first overflow seriously and classification performance got better.Underflow diameter and feed pressure have significant effects on the first stage separation and the second stage classification of the device,and have small effects on the first stage classification,and have no obvious influence on the performance of second classification.Regarding the separating and classifying cyclone device with magnification overflow shunting,inclined plane studies were tested.The results show that,inclined plane have significant effects on the first stage classification and separation of the device,and have no obvious influence on the performance of second classification.The ash of two underflow decreased with the increase of diversion inclined plane,discharging gangue of first underflow increased and the coarse size of first overflow decreased gradually.But coarse particle level is still more and the performance of classification is worse relative to the separating and classifying cyclone device with no-magnification overflow shunting.For the upright and inverted two connections of first stage cyclone separator on direct overflow connected cyclone device,underflow diameter and the insertion depth of overflow pipe studies were tested respectively,which used to compare the two connection methods.The results show that,compared with upright situation,the ash of two underflow increased under inverted situation of first stage cyclone separator.It is that can decrease discharging significantly by reducing the first underflow diameter and increasing the insertion depth of first overflow pipe.But in general,discharging of the first underflow is still more and general ash is lower.The CFD numerical simulation is carried out on the two conditions of the first overflow pipe insertion depth and the side overflow connection caliber of separating and classifying cyclone system device with overflow shunting by using Fluent software.The results show that,the increasing of the tangential velocity in the center region of the flow field in the cyclone system is the basic reason for the better effect of the overflow classification.Small connection caliber will cause the radial oscillation of flow filed in the first stage cyclone more serious.Similarly,large connection caliber will make the tangential velocityof flow filed in the first stage cyclone decline sharply and make the radial flow of flow field violent,which results in a decline in overall system performance.The simulation results analyse and confirm test results further in theory.