全粒级尾砂浆的结构-流变-渗流特性及深度脱水机理

The gravity dewatering concentration of metal mine unclassified tailings is lower to paste material preparation. The flocculation settlement stage was paid more attention than the deeply dewatering stage, which cannot solve the problem within the low compression scale and poor permeability, hence the underflow get incomplete dewatering and get segregation. This project intends to answer the core question of " how the high concentration slurry thickening to paste", focus on the flocs- net structure-rheological- percolation coupling relationship of the flocculated tailings, analyze the transformation process of slurry from supersaturated state to near saturation state, define the boundary conditions of deeply dewatering environment, improve dewatering concentration, promote paste filling technology progress. The project contains 3 sections, ①The high concentration dewatering performance: analysis of influence of material slurry maximum thickening concentration, dewatering rate, to reveal the dewatering power, path, model and the rules of solid-liquid flow within the paste preparation process. ②The multi factor coupling mechanism of dewatering: propose the certain hypothesis, of which the rationality will be verification by multi factors of the orientation characteristics of flocs net unit, shear rheological resistance source, thixotropic behavior characteristics. ③The definition of the hypothesis: discuss the limiting dewatering concentration under coupling conditions, presents a model for the boundary conditions of the critical shear rate and critical seepage head, reveal the deeply paste dewatering mechanical mechanism

金属矿全粒级尾砂重力脱水浓度低制备膏体困难。传统研究关注前期絮凝沉降过程，忽视了由高浓度至膏体状态的深度脱水过程，未解决床层压缩程度低渗透性能差的难题，导致脱水不彻底料浆分层离析。本项目拟回答“高浓度浆体浓密至膏体”的核心问题，从全尾砂絮网结构-流变-渗流耦合关系切入，分析浆体由过饱和态向近饱和态的转变过程，提出“深度脱水环境界定”假说并进行验证，形成膏体脱水制备理论，推动膏体充填技术的进步。开展3方面研究：①高浓度浆体脱水效果：分析料浆脱水极限浓度、脱水速度影响规律，阐明脱水动力、路径、方式，揭示膏体制备过程中的固液运移规律；②多因素耦合脱水机理：提出假说，从絮网单元体定向特征、剪切流变阻力来源、触变行为对特性的影响等多角度验证假说的合理性；③深度脱水环境界定：分析耦合条件下的极限脱水浓度，提出临界剪切速率与临界渗流水头等深度脱水环境边界条件模型，揭示深度脱水制备膏体的力学机理。

金属矿全粒级尾砂重力脱水浓度低制备膏体困难。本项目针对全粒级尾砂的深度脱水制备膏体材料的过程，开展全粒级尾砂浆的结构-流变-渗流特性及深度脱水机理研究，取得了以下研究成果：.主要内容：研发小型连续浓密试验平台，开展了全尾砂浓度脱水、浆体流变检测、床层逆向渗流实验研究；对脱水后的料浆进行CT扫描与三维重构实现流变影响下的孔隙结构演化定量分析；对孔隙重构体进行渗流模拟，分析了结构演化对逆向渗流脱水的影响机制。.重要结果一：探明了高浓度至膏体状态转变过程的脱水机制。某铜矿全尾砂浆体达到膏体状态的临界浓度为68.1%。利用搜索算法识别压缩絮团中的孔隙结构，并对孔隙结构进行分类，通过建立孔隙网络模型，实现了絮网单元体结构和定向特征变化的定量表征和分析，发现剪切流变对运移水分的通道影响较大。球体数量由1302降低至1086，减小幅度达到了16.59%；棍体数量由7547降低至5735，减小了24.01%。提出球棍比的概念，实现了细观孔隙结构变化的定量分析，可以表征压密絮团排水的来源和比例，针对剪切流对球棍比的影响展开了排水机理分析。.重要结果二：全粒级尾砂浆深度脱水的结构-流变-渗流耦合作用机理。根据絮网结构三维特征提出了絮团破坏模型，阐明了剪切流变作用对絮团的定向影响机制，建立絮团定向指标与流变参数响应关系模型；剪切前后逆向渗流的平均流速有大幅度降低，由1.264μm/s下降至0.813μm/s，降低了35.68%，表现为孔隙流线通道减小，流线密度降低；绝对渗透率降低了31.35%，流速下降趋势和绝对渗透率基本吻合。剪切流变破坏絮网结构，颗粒重新排列定向，水份在压差作用下渗流脱水。.重要结果三：深度脱水环境界定。分析耦合条件下的极限脱水浓度，提出临界剪切速率与临界渗流水头等深度脱水环境边界条件模型，揭示深度脱水制备膏体的力学机理。计算了料浆由高浓度状态上升为膏体状态的深度脱水环境参数。当浓度达到70%，孔隙率低于40.36%，渗透系数为0.93×10-5cm/s，绝对渗透率为1771.84mD，流动指数n=1时，认为达到了膏体状态，检测值为膏体临界脱水环境参数。