尾矿浓密过程的导水通道分布和演化特征

Distribution and evolution characteristics of channeling during tailings thickening

基于室内小型全尾砂动态浓密实验系统,在相同固体体积分数尾矿料浆和絮凝剂添加量的条件下,进行不同初始泥层高度和耙架转速的6组对比试验。首先,理论分析泥层脱水过程中超孔隙水压力耗散并转化为有效应力的过程;其次,根据不同条件下的浓密过程中超孔隙水压力的变化趋势,建立泥层固体体积分数与泥层有效应力的指数函数关系,研究对不同试验条件对尾矿料浆凝胶点固体体积分数和泥层最终有效应力的影响;最后,依照泥层有效应力增长与导水通道演化存在相互关联的机制,结合在泥层顶部和浓密试验柱侧壁对导水通道微型结构的观测,探讨浓密过程泥层中导水通道的分布和演化规律。研究结果表明:导水通道的产生和发展是导致泥层超孔隙水压力耗散和有效应力增长的主要原因,按导水效果和持续时间可将其划分为稳定导水通道和不稳定导水通道2种类型,具有稳定结构的导水通道有利于提高泥层料浆脱水程度。

Based on laboratory pilot dynamic thickening system,6 batches of parallel trials with different initial bed heights and rake speeds were carried out,and the unclassified tailings slurry with same solid volume fraction and flocculant dosage was used in these trials.Firstly,the transformation of excess pore pressure dissipation and effective stress accumulation during thickening was theoretically analyzed.Secondly,the exponential function between solid volume fraction and effective stress of bed was established according to the trend of excess pore pressure of thickening.Thirdly,different influencing factors on the solid volume fraction of gel point and final effective stress were analyzed.Finally,according to the correlation mechanism between effective stress growth and channeling evolution,the distribution and evolution of channeling during the thickening process were discussed combined with the observation of microstructure of channeling at the top of bed and the wall of thickening column.The results show that the generation and development of channeling is the main reason for excess pore pressure dissipation and effective stress accumulation.Two types of stable and unstable channelings are proposed according to the water diversion effect and duration.More importantly,channeling with stable structure is beneficial to improve dewatering extent of tailings slurry.