浮选柱三相泡沫特性对高灰细泥机械夹带作用机制的研究

The increasing proportion of high ash, difficult to float, fine and micro-fine particles in coal slime resulting from higher level of mining mechanization, revolution of heavy medium separation process and widely application of three-stage "coarse particle heavy medium separation & coarse slime separation & fine slime flotation" process will definitely contribute to clean coal contamination problem in coal slime flotation. Cyclonic Micro-bubble Flotation Column, an equipment well acknowledged for advantage in treating fine and micro-fine coal slime, still shows limitations in ash rejection of -0.045mm micro-fine coal slime. Therefore it is urgent to tackle the key scientific problem concerning worse separation effect of high ash, high proportion -0.045mm micro-fine coal slime and clean coal entrainment problem caused by transportation of high ash fine slime by the froth. In this program, researches will be conducted on observation and the oretical analysis of both the gas-liquid two phase and gas-liquid-solid three-phase froth properties using particle image velocimetry, high speed dynamic analyzer and microscopy method to better understand the particle moving behavior in flotation column froth. A particle kinetic model based on three-phase froth properties as well as a recovery model of high ash fine slime will be systematically built to reveal the mechanism of high ash fine slime entrainment in flotation column froth. Based on these findings, structure and process optimization of cyclonic micro-bubble flotation column would be conducted to achieve high precision separation of high ash fine coal slime. These researches will provide theoretical basis and technical support for perfection of flotation basis theory and exploitation of efficient column flotation equipment and process matching large scale heavy medium coal preparation plant.

随着采煤机械化程度提高，重介选煤工艺变革，“粗颗粒重介分选+粗煤泥分选+细煤泥浮选”三段式流程推广，导致入浮煤泥中高灰、难浮、细粒和微细粒煤泥比例增大。旋流微泡浮选柱分选细粒和微细粒煤泥虽具有一定优势，但仍迫切需要解决高灰高含量-0.045 mm粒级煤泥分选选择性差、泡沫中夹带高灰细泥污染精煤的关键科学问题。本项目拟采用粒子图像测速仪、高速动态分析仪和显微技术等分析、测试手段，开展旋流微泡浮选柱内气液两相和气液固三相泡沫特性的观测及理论分析，研究浮选柱三相泡沫中固体颗粒的运动规律，建立基于三相泡沫特性参数的颗粒动力学模型和高灰细泥机械夹带回收率模型，系统揭示浮选柱三相泡沫中高灰细泥机械夹带机理，进而探寻适宜于高灰高含量细煤泥高精度分选的旋流微泡浮选柱结构及工艺参数优化、改进方法。为完善浮选基础理论、开发应用与大型重介选煤厂配套的高效柱式浮选设备和工艺提供重要理论依据和技术支持。

本项目构建了旋流微泡浮选柱分选试验及观测系统，完成了代表性试验煤样采集、制备及分选研究，确定了浮选精煤中代表性污染矿物的种类。探明了浮选柱气泡特性参数对气液两相泡沫特性参数的影响规律，揭示了浮选柱气液两相泡沫衰变机理。阐明了固体颗粒表面改性对颗粒表面性质及泡沫特性参数的影响规律，揭示了浮选柱三相泡沫中疏水煤粒和亲水矿粒的宏观运动行为和微观运动特性，并研究了颗粒与气泡间的作用力。阐释了与泡沫性质有关的浮选柱操作参数对三相泡沫结构及精煤质量的影响机制和固体颗粒性质对三相泡沫特性的作用机理，进行浮选柱三相泡沫中颗粒动力学模型及亲水矿粒机械夹带回收率模型的建立及验证。揭示了浮选柱三相泡沫中亲水矿粒的机械夹带机理，包括气泡尾涡夹带回收机制、边界层粘附回收机制、多气泡液流携带回收机制和细泥罩盖回收机制；提出了复合重力沉降与泡沫区内置倾斜板两种强化三相泡沫排液行为、减少高灰细泥夹带污染的措施。