Method to reduce sand loss of spiral classifier

Date: Jul. 14, 2021

The spiral classifier is an old product. According to the different depth of the spiral blades at the overflow end of the spiral classifier into the overflow surface, it is divided into low weir type, high weir type, and submerged type. In building construction, a high weir spiral classifier is often used to wash sand.

This spiral classifier is usually installed on an inclined concrete foundation. When working, the mud mortar enters from the side of the inclined classification tank, and the sand with a larger particle size sinks into the bottom of the tank, and is conveyed by the spiral to the upper overflow outlet of the tank. The particle size is smaller than The sand particles are discharged with the overflow weir at the lower end of the mud mortar tank. In the course of use, we found that the spiral classifier is not only complex in structure and large in volume, but also because the rear support is lower than the overflow end, the upper edge of the spiral bearing seat is immersed in muddy water for a long time. Although there is a lifting mechanism, the maintenance is still inconvenient. In addition, the loss of sand larger than 0.15mm was 11.3%, causing serious sand loss.

Improved Design
(1) Improvement of the driving device The author made appropriate changes to the old spiral classifier under the inspiration of observing similar foreign products. Reasonably select technical parameters in the design, reduce costs as much as possible, improve performance, and take into account the finalization, standardization, and generalization of the product. We use the wall panels on both sides of the sink as the support point of the cross shaft of the driving device, and change the sliding bearing in the original cross shaft to a rolling self-aligning bearing. Because the screw shaft is long, although there is a self-aligning bearing, its adjustment is still limited. Therefore, the motor, reducer and cross shaft are integrated, which makes it easy to adjust the concentricity of the screw shaft and solves the premature failure of the bearing due to misalignment. The problem.

(2) Improvement of rear support
This product is a single spiral sand washing mechanism. The spiral blades at the overflow end are all sunk below the overflow surface. If the sealing effect is not good, sediment will easily enter the bearing of the rear support, which will cause plastic deformation and wear failure of the self-aligning bearing in the support. To this end, we changed the sealing device outside the sink and fixed it on the back wall. The sealing device with layered sealing is simple and has a better sealing effect. In order to facilitate cleaning of the dirt in the tank, a water inlet and a drain are set at the tail, eliminating the lifting mechanism of the prototype spiral classifier, and a return-shaped overflow tank that can be assembled and disassembled is provided at the tail. This kind of back-shaped overflow trough can prolong the retention time of the mud mortar in the tank, so that the larger sand particles sink into the sloped back-shaped groove, pass the block of the back-shaped groove plate, and then return to the water tank. In this way, the loss of sand particles is reduced. In order to improve the dehydration effect, the upper sand discharge port cannot be opened too much. According to the phenomenon that when the solid spiral blade shaft conveys the material in the symmetrical tank, the sand and water gradually deviate to one side from bottom to top. The spiral shaft is not concentric with the center of the tank, and the sand outlet is still in the center of the tank.

Figure of the rear support of the drive unit sink overflow back to the groove. The structure of the single spiral sand washer. The rear wall support of the sink. The self-aligning bearing skeleton. The oil seal type seal ring. The effect of the shaft head structure reformation. The drive device is small in size and compact in structure, which can improve The service life of the bearing and the protection of the motor from overloading can also save steel and eliminate the cumbersome mechanism. At the same time, a set of distinctive design, processing, assembly and debugging methods are summarized. Compared with the spiral classifier, the modified product has the advantages of large production capacity, light weight, less water and electricity loss, minimal loss of sand and gravel, stable working performance, and convenient assembly and disassembly and maintenance. At present, this classifier has been put into the Three Gorges sand and gravel system project.