单气泡尺度下矿浆紊流度对颗粒-气泡矿化动力学的影响

Effect of flotation pulp turbulence intensity on bubble-particle mineralization dynamics at a single bubble scale

颗粒-气泡相互作用是浮选的基本核心作用单元,湍流作为浮选矿浆的基本特征显著影响着颗粒-气泡矿化效率和浮选回收率。文章以0.25-0.125 mm粒级无烟煤颗粒为研究对象,借助颗粒-气泡黏附动力学测试系统研究了不同矿浆紊流度条件下颗粒-气泡黏附角(BPAA)随时间的变化规律,并使用经典浮选动力学模型对单气泡尺度下的颗粒-气泡矿化动力学过程进行了拟合分析:结果表明:随着矿浆紊流度逐渐增高,最大BPAA和颗粒-气泡矿化动力学速率均呈现先增加后减小趋势,造成这种变化趋势的原因是低紊流度条件下提高紊流度可以促进颗粒悬浮,进一步提高颗粒-气泡碰撞概率,但紊流度过高则会增加颗粒-气泡脱附概率;采用Matlab软件进行拟合分析发现,单气泡尺度下的颗粒-气泡矿化动力学最符合经典一级动力学模型,因此适度提高矿浆紊流度可以强化煤炭颗粒与气泡的黏附,而强矿浆剪切作用可以破坏矿化气絮体稳定性,促进黏土矿物与气泡分离。

Bubble particle interaction is the basic core active element in flotation process,and the turbulence as the basic feature of flotation pulp exerts a significant bearing on bubble-particle mineralization efficiency and flotation recovery.Test is made with the 0.25-0.125 mm anthracite as the object to explore the low governing the variation of the bubble-particle attachment angle(BPAA)with time at different tur-bulence intensities with the particle-bubble adhesion kinetics testing system,and analyze the bubble-particle mineralization process at a single bubble scale using classic flotation dynamic models.Test result shows that with the increase of turbulence in tensity,the maximum BPAA value and the particle-bubble collision rate all tend to first go up and them drop down.This is attributed to the fact that with the turbulence at a lower intensity level,the in crease of turbulence inten sity in this case can help promote suspension of particles and hence in crease particle-bubble collision probability while at an excessively high turbulence in tensity,the probability of having the particles detached from bubble surface is increased.It is revealed through fitting analysis using Matlab that the particle-bubble mineralization dynamics at the single bubble scale can find a best fit with classic primary kinetic model.So,a moderate in crease of turbulence intensity can help strengthen attachment of particles onto bubble surface while an intensive pulp shearing action may produce an adverse effect on the stability of the mineralized gas flocs and hence promote the detachment of clay minerals from bubble surface.