空化过程微纳米气泡性质及其对细粒矿物浮选的影响

Micro-nano bubbles properties induced by hydrodynamic cavitation and their influences on fine mineral flotation

利用一套自行设计的,运用水力空化原理产生微纳米气泡的发生装置,通过激光粒度仪,纳米粒径电位分析仪以及表面张力仪等手段研究水力空化过程产生的微纳米气泡性质,并考察了在浮选药剂溶液中预先引入微纳米气泡对细粒一水硬铝石矿物浮选行为的影响。结果表明:水力空化预处理油酸钠溶液能够产生微纳米级气泡;随油酸钠浓度、溶液pH值和空化强度的增大,溶液中微纳米气泡的平均尺寸分布不断减小;空化时间较短时,油酸钠溶液中能够形成较多的亚微米及纳米级气泡,随空化时间延长,溶液体系微纳米气泡的平均尺寸分布增大。外加充气为空化体系提供了大量气核,促使空化过程产生大量微纳米气泡,气泡兼并现象显著导致测定的微纳米气泡尺寸分布逐渐增大;微纳米气泡具有较好的稳定性,尤其是亚微米及纳米级气泡,其能在溶液体系稳定存在1h以上;预先在浮选药剂溶液中引入微纳米气泡能够显著强化细粒一水硬铝石矿物浮选,尤其是在低药剂浓度条件下。

By using a homemade micro-nano bubbles generator based on hydrodynamic cavitation principle,the properties of micro-nano bubbles generated and their effects on the flotation behaviors of fine diaspore minerals were studied through laser particle size analyzer,Zetasizer and surface tension meter,etc.The results show that hydrodynamic cavitation pretreatment of sodium oleate solution(NaOl) can produce micro-nano bubbles in the bulk solution.With the increase of NaOl concentration,the pH values of solution and cavitation intensity,the average size distribution of micro-nano bubbles in the solution continuously decreases.When the cavitation time is short,submicron and nanoscale bubbles can be formed in NaOl solution,while as cavitation time raises,the average size distribution of bubbles in the solution system increases.The additional aeration provides a large number of gas nuclei for the cavitation system,which promotes the generation of a large number of micro-nano bubbles in the cavitation process,and the bubble merger results in a significant increase in the size distribution of the micro-nano bubbles.Micro-nano bubbles have good stability,especially submicron and nanoscale bubbles,which can stably exist in the solution system for more than one hour.Lastly,the introduction of micro-nano bubbles in the flotation agent solution before flotation can significantly enhance the fine diaspore flotation,especially at low agent concentration.