Spiral grader is widely used in the concentrator to shunt mineral sand with the ball mill , forming dubbed closed circuit. In the gravity concentrator, it is used for grading sand and mud, and in metal beneficiation process for the pulp particle size classification, and in ore washing operations for desliming, dehydration and other operations. The machine has the advantages of simple structure, reliable work, convenient operation and other characteristics. Spiral grader structure features: Grader is mainly composed of a driving device, a spiral body, tank, a lifting mechanism, a lower seat (Bush ) and discharging valve. The base of the machine adopts a channel, the machine adopts welded steel. The water inlet of spiral axle, axle is using cast iron, wear-resistant durable and lifting device consists of two kinds of electric and manual. Spiral grader working principle: Spiral grader is utilizing the principle that different sizes, different weight of solid grains , thus in the liquid the different settling velocity. Fine mineral particles float in the water and overflow ,while coarse particles sink to the bottom, by the screw pushing discharged from the upper, which carry out the mechanical grading. It can grade and filter the grinded powder in the mill , and then the coarse material using on-chip spiral vane is screwed into the mill feed inlet, fine material filtered out discharged from the overflow tube.