溶气在微细颗粒疏水表面析出动力学的研究

项目名称： 溶气在微细颗粒疏水表面析出动力学的研究

项目编号： No.50874031

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 陈泉源

作者单位： 东华大学

项目金额： 30万元

中文摘要： 目前品位低、嵌布粒度细小、组成复杂的难选矿石所占比例日益增加，矿石细磨将难以避免，导致入选物料中-5μ24494;细颗粒比例增加，而含-5μ24494;细颗粒的物料分选十分困难。本项目研究了-5μ24494;细颗粒溶气异相析出浮选过程中固/水/气界面传质行为及相互作用，研究了溶气在疏水颗粒表面析出动力学及其选择性调控方法。具体工作包括：（1）采用显微高速摄像-图像计算机分析、激光散射仪，表征气泡和颗粒，研究微气泡对微细颗粒选择性分散的影响；（2）在气泡/颗粒界面作用力、微观表面接触角测定的基础上，根据界面作用能垒，模拟计算气泡在疏水颗粒表面成核的临界直径、成核速率、生长速率，研究了它们与矿物颗粒表面疏水性强度（表面微观接触角）、矿浆物理化学参数之间的关系；（3）采用原子力显微镜、显微高速摄像，在仿真（模拟溶气异相析出浮选）条件下，观测了纳米气泡、微气泡在矿物颗粒疏水表面形成和聚集并大过程；（4）研究了不同气体溶解后在不同矿物表面以及同一矿物的不同疏水性程度的表面，异相析出形成纳米气泡、微气泡的行为及存在的差异。通过调控颗粒表面疏水性及溶解气体组成，并利用溶气及微气泡对微细颗粒选择性活化作用，可以改善分选的选择性。

中文关键词： 浮选；纳米气泡；微细颗粒；疏水效应；动力学

英文摘要： The fine grinding of ore is necessary due to the increase of complex mineral resources nowadays, which results in a significant increase of micro-particles (-5μ in the raw material for mineral processing. It is well known that the selective separation of -5μparticles is very difficult in conventional flotation processes due to the very low collision possibility between particles and bubbles. In this work, we examined the interaction and mass transfer between interfaces of solid/liquid/gas in micro-particle flotation with dissolved gas, focusing on the dynamics of dissolved gas precipitation on the hydrophobic surfaces of fine particles and methods for improving the selectivity of the gas precipitation. The following scientific studies have been done on -5 μpure minerals including rutile and quartz as well as fine grinding iron ore. (1) Photographic methods using a long-working distance microscope in combination with digital image processing and laser diffraction technique was used to characterise the particles and bubbles and investigate the influence of dissolved gas and micro-bubbles in the pulp on the selective dispersion of micro-particles; (2) Based on the measurement of the interface force and micro-surface contact angle, the critical size of bubble nucleation, the nucleation rate and growth rate of bubbles was calculated according to energy barriers. And the statistical relations of these factors with the surface hydrophobicity (micro-surface contact angle) were established; (3) Atomic force microscope and photographic methods in combination with digital image processing were employed to observe the process of formation and aggregation of nano-bubbles and micro-bubbles on the hydrophobic surfaces of micro-particles. The relationship of the surface hydrophobic intensity and nano-bubble size and numbers has been investigated; (4) The precipition of different dissolved gases at different mineral particles and different hydrophobic surfaces of the same mineral particle have been studied. It is found that the separation selectivity can be improved by the regulation of hydrophobicity of particle and composition of gases. This work established the dynamic equations of gas dissolution in liquid, precipitation and aggregation of bubbles on the hydrophbic surfaces of micro-particles, and expand the knowledge of particle/bubble aggregation and particle hydrophobicity.

英文关键词： Flotation; Nano-bubble; Micro-particles; Hydrophobicity; Dynamics