浮选颗粒-气泡间疏水力来源机制及其动态粘附基础研究

Flotation is one of the most mature separation methods for fine particles, in which bubble-particle attachment is the key process. At present, hydrophobic force as the driving force for bubble-particle attachment in flotation has been widely recognized. However, the mechanism of the origin of the hydrophobic force between bubble and particle is still not well-understood. Meanwhile, flotation attachment is always accompanied by hydrodynamic force. Little attention is paid to the dynamic attachment mechanism between bubble and particle. This project will consider oxidized ore quartz and sulphide ore sphalerite as the research objects. A flotation micro-nano mechanics apparatus, flotation wetting film apparatus, and large-scale atomic/molecular massively parallel simulation will be employed. Firstly, the mathematical model of the hydrophobic force based on surface contact angle will be established. The variation of the hydrogen-bond network structure and dipole orientation of water molecules, hydrophobic force, and average force potential of the system during bubble-particle interaction will be studied. The energy functional mechanism of the hydrophobic force induced by the interfacial water structure will be revealed. The temporal and spatial evolutions of hydrodynamic pressure and disjoining pressure in a thin water film during dynamic attachment will be investigated. The mechanism of dynamic bubble-particle attachment under the combined action of hydrophobic and hydrodynamic forces will be revealed. On this basis, dynamic attachment probability model will be established. The results of the project will not only further clarify the bubble-particle attachment mechanism but also have important practical values for the process intensification of refractory minerals flotation.

浮选作为最成熟的细粒选矿方法之一，颗粒-气泡粘附是其核心作用单元。目前疏水力作为浮选粘附的驱动力已形成共识，但颗粒-气泡间疏水力的来源机制仍未明晰。同时浮选粘附始终伴随着水动力作用，颗粒-气泡动态粘附机理未引起足够关注。本项目以典型氧化矿石英及硫化矿闪锌矿为研究对象，采用浮选微纳力学测试仪、浮选液膜分析仪等分析测试手段与大规模原子分子并行模拟相结合，首先构建基于表面接触角的疏水力数学模型，研究颗粒-气泡相互作用过程中水分子氢键结构与偶极取向、疏水力大小及体系平均力势的变化规律，探明界面水分子结构诱发颗粒-气泡间疏水力的能量作用机制；研究动态粘附过程中液膜水动力压力与分离压力的时空演化特征，揭示疏水力-水动力联合作用下的颗粒-气泡动态粘附机理，并在此基础上构建浮选颗粒-气泡动态粘附概率模型。项目研究成果不仅有助于进一步明晰颗粒-气泡粘附机理，对难浮矿物浮选过程强化实践同样具有重要意义。

浮选作为最成熟的细粒选矿方法之一，颗粒-气泡粘附是其核心作用单元。目前疏水力作为浮选粘附的驱动力已形成共识，但颗粒-气泡间疏水力的来源机制仍未明晰。同时浮选粘附始终伴随着水动力作用，颗粒-气泡动态粘附机理未引起足够关注。项目采用浮选微纳力学测试、大规模原子分子并行分子动力学模拟等研究手段，探索了接触角对颗粒-气泡间疏水力的影响规律，构建了呈单指数数学模型衰减的疏水力数学模型。探索了接近次数、无机盐离子、气体溶解度等对疏水力的影响规律，基于和频振动光谱（SFG）检测与大规模原子分子模拟揭示了界面水分子结构诱发疏水力的能量作用机制，发现亲水基板表面可以形成密度大于体相水的结构水层，并且随着疏水程度的增大，结构水层密度减小直到消失，导致疏水界面水分子处于热力学不稳定状态。基于Stokes-Reynolds-Young-Laplace(SRYL)方程耦合求解，研究了动态粘附过程中液膜水动力压力与分离压力的时空演化特征，揭示了疏水力-水动力联合作用下的颗粒-气泡动态粘附机理。去离子水中，AFM力测试法发现微米气泡与疏水基板间疏水力衰减长度小于4nm，当液膜厚度薄化至疏水力作用程时，总分离压力转向吸引，膜薄化驱动压力急剧升高，液膜快速薄化并破裂。疏水力诱发液膜破裂的机理可以由Frumkin-Derjaguin等温线来解释，疏水分离压可以克服短程范围内的排斥性范德华分力压，同时可以使得系统自由能变化率变为负值，诱发液膜自发破裂。进一步使用SRYL方程对宽尺度雷诺数下疏水玻璃气泡间亚稳态润湿膜排液动力学进行模拟，考察了疏水力-水动力联合作用的浮选颗粒-气泡动态粘附机理，发现液膜破裂发生在气泡远离玻璃基板过程，流体抽吸力驱动液膜进入疏水力作用程并薄化至临界破裂厚度发生粘附，这种基于流体抽吸和疏水力协同作用下的液膜破裂机制在颗粒气泡粘附中扮演着重要作用。最后完成了颗粒气泡诱导时间的理论求解，在传统势流方程的基础上构建了基于疏水力-水动力联合作用的浮选颗粒-气泡动态粘附概率模型。项目研究成果不仅有助于进一步明晰颗粒-气泡粘附机理，对难浮矿物浮选过程强化实践同样具有重要意义。