Experiment and Mechanism Study on Floatation of Fine Coal by Nano Bubble Flotation Column

摘要

Flotation is a fine particles separation technology that is the most effective and the most widely used.The range of narrow flotation particles is the defect of traditional flotation technology,it is about between 10mm to 100mm.Too large particles or too fine particles will result in low flotation efficiency.The main reasons are the collision probability between fine particles and bubbles is small and the probability of loss large particles.the attachment probability of coarse particles and bubbles is small,and the probability of coarse particles falling off the bubbles is large. There are many ways to form nanobubbles, Venturi tubes are used to form nanobubbles by hydrocavitation .Flotation column has good performance, and it is widely used in the flotation field.For the fine coal,venturi tubes are used to create nanobubbles,and the flotation recovery effect of nanometer bubbles on fine-grained coal is studied by changing the conditions of flotation column.On this basis, the recovery mechanism of nanometer bubble to fine coal is described.Experimental results show that the recovery rate can be increased by 10% to 39%. Under the condition of adjusting flotation factors,.and the dosage of conventional bubble flotation agents is reduced by more than 1/2. The nanobubbles can concentrate on the surface of hydrophobic particles in the flotation system.Due to the collision and adhesion probability of particles and bubbles is increased by nano bubbles and the probability of particles and bubbles falling off is reduced by nano bubbles,the flotation is optimized.Nano bubbles play a role that is secondary collector because they are preferentially formed on the surface of hydrophobic particles, nanometer bubbles can improve the surface hydrophobicity of particles, which is beneficial to improve the flotation efficiency and recovery.In addition, The nanobubbles can selectively agglomerate hydrophobic fine particles.increase fine particles size, combine the collision and attachment process into one, increase the rate of mineralization, and increase the probability of collection.