Studies On Foaming Performances Of Spraying Bubble Generator

Bubble generator is one of the key parts in flotation equipment, which is employed to create adequate bubbles and facilitate their contact with the mineralized ore pulp. In this thesis, a bubble generator was designed by directly spraying air. In such a foaming process, the initial gas with continuous phase gradually split into tiny and uniform bubbles, thereby influencing the gas volume fraction, the size of bubbles and the depth of penetration in the flotation column. The flotation experiments were further conducted to systematically evaluate the performance of the as-designed bubble generator. The main work and as-achieved results are presented as following.A test platform with visualized two-phase flow field was set up. An algorithm was proposed for digital image processing, including image preprocessing, image binaryzation, image filling, image edge detection as well as characteristic parameter extraction of the bubbles.The bubble dynamics behavior of the bubble generator was investigated under various air inflation, pipe diameter, throat pipe and forepart trepanning. The results indicated that there existed the optimal air inflation for a specific bubble generator. During the real flotation process, the bubble generator could achieve excellent flotation efficiency via controlling the air inflation.The flotation column was designed in the laboratory. Quartz mineral was selected to carry out the flotation experiment. We elaborated the experimental section, data processing and fitted the first class flotation kinetic curve to obtain the flotation rate constants, thus evaluating the advantages and disadvantages of the corresponding bubble generators.Three factors were studied by orthogonal tests to evaluate their influences on the performances of bubble generators. The recovery of the flotation column were impacted by these factors, in terms of degree, air inflation>pipe diameter of bubble generator> exit throat pipe diameter of bubble generator. When the bubble generator worked atB2A3C1, that is, air inflation was20L/min, pipe diameter was6mm, exit throat pipe diameter was0.4mm, the recovery was remarkably enhanced with good flotation efficiency. Meanwhile, the local resistance factor of the bubble generator reduced to form preferable flotation bubble system.