颗粒性质及溶液环境对颗粒-气泡脱附行为的影响机制

Effect of particle properties and solution environment on the detachment behavior between particle and bubble

  • 摘要: 脱附是浮选颗粒-气泡矿化的关键子过程,决定了浮选最终效率及粒度上限,但浮选颗粒- 气泡间脱附行为的影响机制并未清晰。 为系统性探究颗粒性质及溶液环境对颗粒气泡间脱附行为 的影响,通过自主开发的浮选颗粒-气泡黏脱附测试系统及黏附力测试仪,以颗粒气泡间最大脱附 力及气絮体中颗粒临界脱附振幅为依据,对不同颗粒性质及溶液环境下颗粒气泡间脱附力及颗粒 气泡气絮体稳定性进行了系统性试验研究。 结果表明:粒度的提升可增加三相周边周长,从而提升 颗粒气泡间脱附力,但质量增加带来的惯性力减小了气絮体稳定性,整体不利于浮选。 脱附力及气 絮体稳定性均随颗粒疏水性提升而增加,这主要是三相周边周长随颗粒疏水性提升而增加所致。 疏水表面粗糙度提升了颗粒表面接触角,脱附力及气絮体稳定性随之增加。 颗粒形状参数改变了 三相周边周长及三相周边上接触角的分布,且柱状颗粒上表面边缘处接触角取值由 Gibbs 不等式 决定,颗粒接触角滞后性随之改变,颗粒形状因素由此影响了颗粒气泡间脱附行为,不同形状颗粒 脱附力大小整体为圆柱>四棱柱>球体。 准静态环境下测试的脱附力由表面张力决定而溶液黏度 几乎无影响,但气絮体稳定性受表面张力及黏度的联合作用。

     

    Abstract: The detachment between bubbles and particles is one of the key sub⁃processes of bubble⁃particle mineraliza⁃ tion in flotation,which determines the final efficiency and the upper limit of the particle size of flotation.However,the influence mechanism of the detachment behavior between particles and bubbles is not clear so far.To systematically ex⁃ plore the effects of particle properties and solution environment on the detachment behavior between particle and bub⁃ ble,the test system of bubble⁃particle attachment and detachment,and the adhesion force measurement system were used. The detachment force between particles and bubbles and the stability of the aggregate were distinguished by the maximum detachment force between particle bubbles and the critical detachment amplitude of the aggregate.The results show that the detachment force between particles and bubbles increases with the increase of particle size through increasing the circumference of three⁃phase contact line, while the stability of the aggregate reduces due to the higher inertia,which is not conducive to flotation on the whole.The detachment force between parti⁃ cle and bubble and the stability of the aggregate increase with the increase of surface particle hydrophobicity due to the longer three⁃phase contact line. The roughness of the hydrophobic surface improves the hydrophobicity of the particle,thus the detachment force and the stability of the aggregate increase accordingly. The particle shape changes the circumference of the three⁃phase contact line and the distribution of contact angles on the three⁃phase con⁃ tact line.Meanwhile,the contact angle at the edge of the upper surface of columnar particles takes a range of values within the limits defined by the Gibbs inequality,the detachment behavior between particle and bubble is influence by them.In general,the detachment force of particle with different shape decreased gradually in the order of cylinder, quadruplex and sphere.The detachment force tested in a quasi⁃static environment is determined by the surface tension while the solution viscosity has almost no effect,but the stability of the aggregate is affected by the surface tension and viscosity.

     

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