The Research Of Weak Cyclonic Spearator For Fine Coal

In this paper, two types of slurry separator working in low pressure were designed for coarse coal slime separation, based on the coal slime hydrocyclone gravity separation column. And the separation efficiency was evaluated.First, single-stage weak-rotating slime separator (abbreviated as WSS) was designed. And the influence of structure and operating parameters on separation processing in low pressure were systematically studied, such as the size of feed, the height of cylinder, the length of the sleeve, the size of bottom outlet and feed pressure. The size of feed inlet greatly influenced separation performance. Big size is suitable for roughing operations, little for accurate selection. With the increasing of cylinder height, the shorter of sleeve length, the bigger of bottom outlet, and the lower of operating pressure, the ash content of product decreased.On the basis of single-stage experiments, two-stage and multi-product separator was developed. The overflow of first separator was divided into two parts by a guiding plate. The low-ash-content part was discharged from the overflow pipe. And the part of high-ash-content entered into the second WSS along the tangent and was cleaned again. So some products can be obtained through one separation. The underflow of first is high-ash-content tailing, and the underflow of second is middling, the overflow of the two separator is low-ash-content clean coal.The influence of structure parameters and operating parameters (inlet pressure, shape of guiding plate, inlet diameter, overflow and side-overflow diameter of the second WSS,) on processing was also investigated. At the same time, the separation effect was assessed, when the second WSS was replaced by coal slime dense-medium-separation column. The results of research stated that the WSS has the best separation efficiency when the guide plate is located in No.l position. The ash content of underflow and overflow increased with the bigger of inlet-gate diameter in two WSS, but the ash content of+0.25mm increased and the ash content of-0.25mm decreased in side-over flow of the second. When the second side-overflow gate grow bigger, the ash content of first overflow, the second side-overflow and underflow raised, but the ash of the second reduced. When the diameter of the second side-overflow gate increased to a certain value, there’s no overflow in the second WSS. The diameter of second overflow pipe had almost no influence on the preparation. With the operation pressure increasing, the ash of first over flow and underflow added, the ash of second side-overflow and underflow were the same. But the ash of the second overflow was opposite. When the second WSS was replaced by coal slime dense-medium-separation column, the ash of first overflow decreased then increased, the ash of other products all increased.From the results of experiment, it can be seen that the first section of WSS is a rough operator. Its main function is discharging part of waste rock under the high density, then separated part of the clean coal utilizing the weak-rotating in cyclone. At the same time, the high ash product went into the second section and rewashed there, so the total separation efficiency would be enhanced. The impact of second section was accuracy-selection. For+0.25mm group, the mean probable error (Ep) is0.08, and the separation accuracy was high. For+0.125mm group, the value of Ep is0.14. Comparison of the ash of+0.125mm group from the two sections of WSS, it can be found that, the lower limit of separation is0.125mm, So the WSS is a good separation equipment for coarse coal slime.Using software of computational fluid dynamics(CFD), the flow field of weak slurry separator was simulated. The contrast analysis of flow velocity, pressure and turbulence intensity was conducted in different separating condition.In addition, a new separation column was designed. The coal slime entered into the equipment from the center of cylinder, and water was injected along the tangent. But the new separator was found having no effect on the preparation of coarse coal slim.