超声波强化褐煤浮选及其作用机制探讨

为强化褐煤浮选,提出了在浮选矿浆中引入超声波的新型浮选方式,结果表明:超声浮选精煤产率比常规浮选精煤产率增加了20.31%,灰分降低了7.94%,其中-0.045 mm粒级产率增加了近2倍。采用筛分、扫描电镜、X射线光电子能谱、诱导时间测定仪等方法研究了超声波对煤泥粒度组成和表面性质的影响,并重点探讨了超声波强化褐煤浮选的回收机理。超声波对煤粒表面的清洗和破碎作用使颗粒表面细泥黏附减少,但并未改变煤粒表面疏水性与亲水性官能团含量。超声波可在浮选矿浆中产生大量微泡,既可吸附于褐煤表面增强其疏水性,又增加煤粒与气泡的碰撞/黏附效率。超声波产生的空化作用在一定程度上可使煤表面的水化膜变薄-不稳定-易破裂,进一步强化了褐煤的浮选回收。

Discussion on ultrasonic enhanced lignite flotation and its action mechanism

For enhancing the flotation of lignite,a new flotation method for the introduction of ultrasonic wave in flotation pulp was proposed.The results show that the yield of ultrasonic flotation clean coal is 20.31% higher than that of the conventional flotation clean coal,the ash content is reduced by about 7.94%,and the yield of -0.045 mm is increased by nearly 2 times.Using screening,scanning electron microscopy,X-ray photoelectron spectroscopy,induction time measuring instrument to study the influence of ultrasonic treatment on slime particle size and surface properties,the mechanism of ultrasonic enhanced lignite flotation was investigated.The effect of ultrasonic cleaning and breaking on the surface of coal particles decreases the adhesion of fine particles on the surface of the particles,but does not change the surface hydrophobic and hydrophilic functional groups.Ultrasonic waves can produce a large number of microbubbles in the flotation pulp,which can be adsorbed on the lignite surface to enhance its hydrophobicity and increase the collisions/adhesion efficiency of coal particles and bubbles.To a certain extent the cavitation of the ultrasonic waves causes the hydration film on the surface of the coal to become thinner-unstable-easy to rupture,further enhancing the flotation recovery of lignite.