Spiral chute suits the fine size ores with particle size of 0.3-0.02mm, such as iron, limeite, chromite, brasses, zirconite, rutile, monazite, xenotimes, tungsten, tin, tantalum, niobium, other ferrous metal with the different gravity property. It owns of the features of steadily working condition, easy controlling, big changes in scope of feeding density, rich concentration ratio, high recovery rate, small cover area, low water consuption, simple structure, free power, big capacity, simpler installation, convenient operation, less investment but high efficiency, etc.