Spiral classifier is composed of a semi circular flume in the bottom, spiral blade, bearings on both ends supporting screw shaft, a spiral shaft transmission device and lifting mechanism.
The pulp feed into the water channel from the feed port in the edge of the trough. In the process of moving to downflow weir of trough, the mineral particles begin to settlle down and decompose. Due to the low settlement speed, fine particles are in a state of suspension, carried down by water current and then discharged through the overflow weir, finally become overflowing. Since the settlement speed of coarse particle is high, the revolved blade is moved to the upper of trough after sinking into the trough, then become sand return and return to the mill for regrinding.
The helical blade of spiral classifier use the radial spokes connecting with the hollow 75u shaft. The two ends of the shaft are installed in the upper and lower bearing, rotating slowly drived by the transmission device at the upper end of trough. The lower end bearing is arranged at the bottom of the lifting mechanism, and the upper and lower position can be adjusted by the lifting mechanism, so that the screw can be raised when the machine is stopped. it can prevent the screw from desilting, causing the overload when starting the machine. Meanwhile, the lifting mechanism can adjust the distance between the blade and the bottom of the groove.
According to the different spiral in the sink location and pulp surface height, spiral classifier can be divided into sinking, high weir and low weir type.
The screw blade of Sinking spiral classifier overflow end has 4-5 rings that all immersed in the pulp with a large settlement area, deep classification pool. And the rotation of screw has little influence on the pulp surface. Therefore, its advantages include the smooth classification surface, high overflow output and fine granularity, which is suitable for the classification of 0.15mm grain size overflow products. It’s usually formed one machine set with the ball mill in the second section grinding in the ore dressing plant.
The overflow weir of high weir spiral classifier is higher than that of lower end bearing of spiral hollow shaft, but lower than the upper edge of the blade edge. The settlement area is larger than low weir, and can adjust the height of overflow weirn in a certain range to change the settlement area, therefore it can adjust the granularity of classification, which is a common used classifying equipment in ore grinding cycle and suitable to separate more than 0.15mm for the overflowings. It’s usually used in the first section ore grinding.
