石英对浮选泡沫稳定性的影响及其机理

Effect of Quartz on the Stability of Flotation Foam and Its Mechanism

泡沫稳定性是影响浮选过程的重要因素之一,为了考察石英对浮选泡沫稳定性的影响,通过泡沫稳定性试验和析液试验,研究石英在不同捕收剂浓度、颗粒粒度和质量浓度下的泡沫稳定性。并通过接触角测量、Zeta电位测试、泡沫光学图像观察、表面张力和矿浆黏度测定,进一步分析石英对浮选泡沫稳定性的影响机理。结果表明,随着十二胺浓度的增加,溶液的起泡能力增强,泡沫稳定性先增加后降低,这主要是由于十二胺使得溶液体系的表面张力显著降低,减缓了泡沫液膜在Plateau通道内排液的平均流速,石英表面疏水性逐渐增大,泡沫稳定性增强。但当十二胺浓度大于60 mg/L时,石英三相接触角超过90°,强疏水性颗粒不再具有稳泡效果,而是遵循桥联-反润湿机理消泡,泡沫稳定性降低;石英颗粒粒度越细,质量浓度越大,使矿浆黏度增大,阻碍了液膜排液,泡沫稳定性增强;析液试验结果说明,石英颗粒粒度越大,泡沫破裂速度越快,该结论与泡沫稳定性试验结果一致;十二胺通过静电作用吸附在石英表面,改变了石英表面的电负性。在浮选试验条件下,有利于形成稳定的泡沫体系;通过泡沫图像发现,石英黏附在泡膜表面,增加了液膜厚度,在两气泡边界区和Plateau Border边界区形成一道紧密排列的壳层结构,增强了泡沫稳定性。

Foam stability was one of the important factors affecting the flotation process.In order to investigate the influence of quartz on the stability of flotation foam,the foam stability and froth drainage test were carried out to study the foam stability of quartz under different concentration of collector,particle size and mass concentration.The influence mechanism of quartz on the stability of flotation foam was further analyzed by contact angle measurement,Zeta potential test,foam optical image observation,surface tension and slurry viscosity measurements.The results showed that with the increase of dodecylamine concentration,the foaming ability of the solution increased,and the foam stability increased first and then decreased.This was mainly because dodecylamine significantly reduced the surface tension of the solution system and slowed down the average flow rate of liquid foam film draining in Plateau channel.The hydrophobicity of quartz surface gradually increased and the foam stability was enhanced.However,when the concentration of dodecylamine was greater than 60mg/L and the three-phase contact angle of quartz exceeded 90°,the strongly hydrophobic particles no longer had the effect of stabilizing bubbles,but followed the mechanism of bridging and anti-wetting,and the foam stability decreased.The finer the quartz particle size was,the greater the mass concentration was,which increased the slurry viscosity,hindered the liquid film drainage and enhanced the foam stability.The froth drainage test results showed that the larger the quartz particle size was,the faster the bubble burst rate was,which was in line with the foam stability test results.The electrostatic action of dodecylamine adsorbed on quartz surface changed the electronegativity of quartz surface.Under the condition of flotation test,it was beneficial to form stable foam system.The foam image showed that quartz adhered to the surface of the bubble film,increasing the thickness of the liquid film and forming a tightly arranged shell structure in the boundary region of the two bubbles and Plateau Border,enhancing the stability of the foam.