摘要
脱附是导致粗颗粒浮选回收率低的重要原因。为了探究疏水性颗粒-气泡间脱附行为机理,利用自制的浮选颗粒-气泡脱附测试系统对不同疏水性颗粒的脱附过程进行观测,借助Image-Pro Plus图像处理软件对颗粒-气泡间接触角、三相润湿周边变化进行测量。结果表明:颗粒脱附过程中接触角并非保持不变,而是存在明显的接触角滞后,接触角为67.0°、83.9°和98.7°的3种疏水性颗粒在达到前进接触角106.7°、119.3°和128.3°后三相润湿周边开始滑动收缩。区别于传统三相润湿周边滑动脱附机制,发现在三相润湿周边滑动阶段为了保证颗粒前进接触角不变,不可避免地会在颗粒表面形成反向毛细颈部,且反向毛细颈部处曲率随着三相润湿周边的收缩而快速增加,并最终在拉普拉斯压力作用下发生断裂脱附,在颗粒表面留下微气泡。同时由于三相润湿周边滑移速度随着颗粒疏水性的增加而降低,因此反向毛细颈部处曲率增加速率随颗粒疏水性的增加而增加,导致最终颗粒表面残留微气泡大小也随颗粒疏水性的增加而增加。
Detachment is an important reason for the low recovery of coarse particles from flotation.In order to investigate the mechanism of detachment behavior between hydrophobic particles and bubbles,the detachment process of different hydrophobic particles was observed using a homemade flotation particle-bubble detachment test system,and the changes of indirect contact angle and three-phase wetting periphery of particles and bubbles were measured with the help of Image-Pro Plus image processing software.The results showed that the contact angle did not remain constant during the particle detachment process,but there was a significant contact angle hysteresis,and the three hydrophobic particles with contact angles of67.0°,83.9°and 98.7°started to slide and contract after reaching the forward contact angles of 106.7°,119.3°and 128.3°.The curvature at the reverse capillary neck increases rapidly with the contraction of the three-phase wetting periphery,and finally fractures under the action of Laplace pressure,leaving microbubbles on the particle surface.At the same time,because the slip rate of the three-phase wetting periphery decreases with the increase of particle hydrophobicity,the curvature increase rate at the reverse capillary neck increases with the increase of particle hydrophobicity,which leads to the increase of the size of the residual microbubbles on the particle surface with the increase of particle hydrophobicity.
作者
尹青临
丁世豪
何琦
邢耀文
张友飞
王钰赛
桂夏辉
YIN Qinglin;DING Shihao;HE Qi;XING Yaowen;ZHANG Youfei;WANG Yusai;GUI Xiahui(National Engineering Research Center of Coal Preparation and Purification,China University of Mining and Technology,Xuzhou 221116,China;School of Chemical Engineering and Technology,China University of Mining and Technology,Xuzhou 221116,China)
出处
《金属矿山》
CAS
北大核心
2021年第12期41-47,共7页
Metal Mine
基金
国家自然科学基金面上项目(编号:21978318)
国家重点研发计划项目(编号:2020YFC1908803)。
关键词
浮选
颗粒-气泡
脱附
高速动态
接触角滞后
flotation
particle-bubble
detachment
high-speed dynamics
contact angle lagging
