低阶煤颗粒-气/油泡间的疏水力常数研究

浮选实验表明油泡对低阶煤颗粒的捕收能力要远强于传统浮选过程的起泡。这主要是由于油泡表面被捕收剂覆盖,其表面疏水性要远高于气泡表面的疏水性。因此,在油泡浮选矿化过程中,低阶煤颗粒-油泡间水化膜的薄化速度要远快于煤颗粒-气泡间的薄化速度。诱导时间测试发现,随着DAH溶液浓度从10~(-7) mol/L增加到5×10~(-5) mol/L时,低阶煤颗粒-气泡间的诱导时间从93 ms下降到12 ms。随着DAH溶液浓度从5×10~(-5) mol/L增加到10~(-3) mol/L时,低阶煤颗粒-气泡间的诱导时间从12 ms增加到35 ms。当DAH浓度由10~(-7) mol/L(纯去离子水溶液)增加到5×10~(-5) mol/L,低阶煤颗粒-油泡间的诱导时间由35 ms降低到10 ms。随着DAH浓度的进一步增加到10~(-3) mol/L时,低阶煤颗粒-油泡间的诱导时间由10 ms增加到25 ms。为了从微观尺度下去表征油泡表面较气泡表面所具有的强疏水性,本文通过低阶煤颗粒-油/气泡间的诱导时间,利用non-DLVO理论及Stefan-Reynolds水化膜薄化模型,拟合出初始水化膜厚度h与疏水性常数K_(132)之间的关系,进而得到了低阶煤颗粒-油/气泡间的疏水力常数K_(132)与十二烷胺盐酸盐DAH溶液浓度的关系。疏水力常数K_(132)拟合结果表明,当DAH溶液的浓度为5×10~(-5) mol/L时,低阶煤颗粒-油泡间的疏水力常数K_(132)约为低阶煤颗粒-气泡间的疏水力常数K_(132)的3倍;当DAH溶液的浓度为10~(-6) mol/L时,前者是后者的15倍。因此,油泡表面较气泡具有更强的疏水性质。从而解释了低阶煤-油泡浮选矿化过程优于传统浮选过程的本质特征。

Investigation of hydrophobicity constants between air/oily bubbles and low-rank coal particles

Flotation results showed that the ability of oily bubbles to collect low rank coal particles is much stronger than that of air bubble in traditional flotation processes.It is because the surface of the oily bubble is covered by the collector,and its surface is much more hydrophobic than the surface of the air bubble.Therefore,in the interaction process of low rank coal particle oily bubble,the thinning speed of hydration film is much faster than that of low rank coal particle air bubble.The results of induction time test indicated that the induction time between low rank coal particles and air bubbles decreased from 93 ms to 12 ms as the concentration of DAH solution increased from 10-7 mol/L to 5×10-5 mol/L.As the concentration of DAH solution increased from 5×10-5 mol/L to 10-3 mol/L,the induction time between low rank coal particles and air bubbles increased from 12 ms to 35 ms.The induction time between low rank coal particles and oily bubbles decreased from 35 ms to 10 ms while the DAH concentration was increased from 10-7 mol/L (pure deionized water solution) to 5×10-5 mol/L.As the DAH concentration increased to 10-3 mol/L,the induction time between low rank coal particles and oily bubbles increased from 10 ms to 25 ms.In order to compare the strong surface hydrophobicity of the oily bubble with the surface hydrophobicity of the bubble from the microscopic scale,the non DLVO theory and the Stefan Reynolds hydration film thinning model were adopted.Based on the induction time results of low rank coal particles oily/bubble,the relationship between the initial hydration film thickness (h) and the hydrophobicity constant (K132) was fitted.Moreover,the relationship between the hydrophobic force constant (K132) and the concentrations of the DAH solution was obtained.The fitting results of hydrophobic force constant (K132) showed that the hydrophobic force constant (K132) between low rank coal particles and oily bubbles was three times than that between low rank coal particles and air bubbles while the concentration of DAH solution was 5×10-5 mol/L.The hydrophobic force constant (K132) between low rank coal particles and oily bubbles was in the order of 10-16 while the concentration of DAH solution is 10-6 mol/L.The hydrophobic force constant (K132) between low rank coal particles and oily bubbles was 15 times than that between low rank coal particles and air bubbles.Therefore,the surface hydrophobicity of the oily bubble was stronger than that of the air bubble.Thus,it concluded that the oily bubble flotation process is superior to the traditional flotation process.