基于倾斜通道强化泡沫排液的细泥夹带抑制机理研究

The entrainment of slime particles into the flotation concentrate is a common problem inhibiting high-efficiency recovery and utilization of fine coal. According to the applicant’s previous research, slime contamination to the flotation concentrate was significantly reduced by constructing inclined channels in the froth zone of the flotation column. However, many essential scientific and technique problems remain unclear for this new froth zone configuration with inclined channels, such as the de-entrainment mechanism, liquid drainage from the froth layer, and the relationship between liquid drainage and slime removal from the froth. In this project, the macro scope behavior of flotation froth, including the spatiotemporal distribution of liquid and slime, will be explored by Electrical Resistance Tomography (ERT) and conductivity probe. By the meantime, micro properties of the froth, such as froth microstructure, liquid drainage mechanism and dynamic slime particle movement, will be captured and analyzed using High Speed Microscopy and related image processing techniques. Based on these experimental results, we hope to systematically illustrate the relationship between froth drainage and slime removal, thereby revealing the slime de-entrainment mechanism in the inclined channels, then derive the slime entrainment model with inclined channels and explore the adjustment strategy for structure and operational parameters of the inclined channels to reduce the slime entrainment. The outputs of this project may optimize the slime entrainment theory, which is significant at the scientific and application level for high-accuracy flotation of fine coal, as well as other fine minerals.

细泥夹带污染是煤泥浮选过程中面临的共性难题，制约着煤泥的高效分选回收利用。申请人前期研究发现，浮选柱泡沫区内构建倾斜通道可有效减少泡沫产品中细泥的夹带，但倾斜通道抑制细泥夹带的机理、倾斜通道内三相泡沫排液与细泥夹带之间的响应机制等关键科学问题尚未阐明。本项目拟采用电阻层析成像技术和电导探头测试技术，从宏观尺度研究倾斜通道对泡沫层中水流、细泥时空分布规律的影响机制；借助高速动态显微技术与图像处理技术从微观尺度研究倾斜通道对泡沫微观结构、排液机制及细泥运动行为的影响规律；系统阐释倾斜通道内三相泡沫排液与细泥夹带之间的响应机制，进而揭示倾斜通道抑制细泥夹带的机理，建立倾斜通道内的泡沫排液模型与细泥夹带模型，探寻有效减少细泥夹带的倾斜通道结构参数调控机制。本项目研究成果有望完善细泥夹带理论，对于实现煤泥的高精度浮选分离具有重要的科学意义和实践价值，对其它矿物的高效浮选分离也具有重要借鉴价值。

煤泥浮选过程中因细泥夹带污染导致浮选精煤灰分不达标的技术难题日益凸显，成为当前煤泥高效分选回收利用技术发展亟待解决的核心难点问题。本项目借鉴倾斜沉降原理在RC逆流分选机和泡沫分离塔中的成功应用效果，提出在浮选设备的泡沫区构建倾斜泡沫通道抑制细泥夹带的设想，并围绕倾斜通道内泡沫排液与细泥夹带之间的内在响应机制开展研究工作。研究结果表明：与竖直通道相比，倾斜通道可提高泡沫排液的速度，降低泡沫产品的水回收率；倾斜通道降低不同高度泡沫层内细泥颗粒的浓度，有利于细泥颗粒向泡沫层底部运动而强化泡沫层对细泥颗粒的脱除效应，减少细泥对最终泡沫产品的污染，降低细泥夹带回收率；细泥夹带回收率与泡沫产品水回收率呈明显的正相关性，阐释了细泥夹带与浮选泡沫排液之间的内在联系机制。揭示了倾斜通道抑制细泥夹带的机理包括两种效应，一是倾斜通道壁面与泡沫之间形成新的排液通道，促进泡沫中液体的流出；二是倾斜通道壁面阻碍泡沫的上浮，导致泡沫兼并、破灭现象加剧。以降低细泥夹带回收率为调控目标，应减小倾斜通道间距，但综合考虑精煤的回收率，倾斜通道间距又不宜过小；倾斜通道倾角应保持在合适的范围，过大或过小的倾角均不利于降低细泥夹带。与常规浮选柱分选指标相比，基于优化后的倾斜通道结构参数构建的新型浮选柱的浮选精煤灰分明显降低，有效降低了细泥污染，实现了对高灰煤泥的高精度浮选分离。本项目研究成果可为煤泥浮选的提质增效、高精度柱式浮选设备的开发提供有益借鉴。