BLL型玻璃鋼螺旋溜槽用于選別細粒（包括細微粒度）的金屬礦物，如鐵礦、鈦鐵礦、鉻鐵礦、硫鐵礦、鎢錫礦、鈮鉭礦、砂金礦、海濱的獨居石、金紅石、鋯英石及有足夠比重差的其它金屬和非金屬礦物選別。本產品由原地礦部唯一指定企業生產，執行行業標準。

螺旋溜槽是根據有用礦物與脈石礦物在比重、粒度、形狀上的差異，在螺旋的斜面產生礦漿動感的離心流膜，在重力和離心力的綜合力場中，利用不同顆粒所受重力、水動壓力和摩擦力，實現有用礦物與脈石分選的。螺旋槽中的水動除作向下的螺旋運動外，還作橫向的循環流動。上層水流流速快，產生較大慣性離心力，甩向槽的外緣。與槽底相鄰的下層水流回轉速度慢，離心力小，在重力作用下從外緣流向內緣，產生二次回流。礦漿中的重礦粒沉降快，沿收斂的螺旋線逐漸移向內緣，最后以精礦形式產生。輕礦物沉降慢，處于礦流表層，流速快，離心力大，在橫向環流作用下，沿擴漸的螺旋線逐漸移向外緣，最后以尾礦形式產出。

Laboratory BLL Glass Fibre Reinforced Plastic Spiral Chute is applicable for separation of fine-grained ( including micro-grained ) metallic minerals such as iron, ilmenite ,chromite, tungsten-tin ore, niobium-tantalum ore, gold placer,  seashore monazite,  rutile and zircon as well as other metallic and non-metallic minerals with adequate difference of specific gravity. The product is made by the only manufacturer designated by the former Ministry of Geology and Mineral Resources, in compliance with the Industrial standards.

Spiral Chute is to make separations of useful minerals from gangues by use of the different particles subject to gravity, hydraulic pressure and friction in the multi-force field through dynamic centrifugal flowing membrane of slurry produced on the inclined surface of spiral based on the differences of useful mineral and gangue in specific gravity, particle size and shape. Water in the spiral chute runs downward spiral movement and also flows in circulation transversely. Water in the upper layer run fast, generating centrifugal force with large inertia to toss toward the outer edge of the chute. Back-flow of water in the lower layer adjacent to the chute bootom runs slowly with small centrifugal force and flows from the outer edge to the inner edge with the action of gravity, generating secondary back-flow. Particles of heavy minerals in slurry settle rapidly and gradually moves toward the inner edge along the converged helix prior to finally being produced as concentrate. Light minerals settle slowly and flow fast in the surface layer of ore flow with large centrifugal force and gradually move toward the outer edge along the expanding helix before finally being produced as tailings.