Spiral classifier (Screw classifier) is widely used for distributing ore in the close circuit with ball mill, grading ore and fine slit in the gravity mill, grading granularity in the flow of metal ore-dressing and desliming and dehydrating in the washing. Advantages are simple structure, reliable working condition and convenient operation. According to the principle that different grains are with different specific gravity and sedimentation rate in the liquid, the fine ore flows in the water and the coarse ore sinks in the bottom. The classifier that has machine grading by discharging from the top can filtrate the materials and send coarse materials to the feeding mouth and discharge the fine material from the pipe. The seat of the machine adopts channel steel and body adopts armor plate and the spiral axle adopts cast iron, so it's durable. The lifting equipment has two types, by electricity and hand.