Bubble size measurement in electroflotation |
| |
| Authors: | Md. Shahjahan Kaisar Alam Sarkar G.M. Evans S.W. Donne |
| |
| Affiliation: | 1. Chemical Engineering, School of Engineering, Faculty of Engineering & Built Environment, The University of Newcastle, Callaghan, NSW 2308, Australia;2. School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia;1. JKMRC, Australia;2. University of Cape Town, South Africa;1. School of Information Science & Engineering, Central South University, Changsha, Hunan 410083, China;2. School of Computer Science, Hunan University of Technology, Zhuzhou, Hunan 412007, China;1. Discipline of Chemical Engineering, School of Engineering, University of Newcastle, 2308, Australia;2. School of Chemical Engineering, University of Queensland, 4072, Australia;3. Homi Bhabha National Institute, Mumbai 400094, India;1. College of Resources and Environment Engineering, Wuhan University of Technology, Wuhan 430070, China;2. School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China |
| |
| Abstract: | A feature of electroflotation is the ability to create very fine bubbles, which are known to improve flotation performance of fine particles. This study was aimed at determining the hydrogen bubble size generated as a function of current density and electrode geometry. Experiments were performed in a viewing cell that allowed direct visualization of hydrogen bubbles being generated and transported away from platinum wire electrodes of 90, 120 and 190 μm in diameter. The detached bubble diameters varied between 15 and 23 μm in diameter, and for each wire diameter, were little influenced by the applied current in the range 150–350 A/m2. The measurements were consistent with those predicted from a simple force balance analysis based on a H2–Pt–0.2M Na2SO4 contact angle of 0.18°. Interestingly, upon detachment, the bubble size increased rapidly, recording up to an 8-fold increase in volume in the first few millimeters of rise, before approaching the steady state diameter of between 30 and 50 μm in the bulk. This increase in bubble size was found to be mostly due to the transfer of dissolve hydrogen into growing bubble while moving through the electrolyte super saturated by dissolved hydrogen gas. The equilibrium bulk diameter was found to be a function of the rate of hydrogen production, bubble nucleation rate, and dissolved gas concentration field. Consequently, electroflotation cells need to be designed to optimise the contact between the supersaturated liquid and the rising bubble plume. By doing this, the volumetric flux of bubbles will be maximised leading to improved flotation performance. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
