全尾砂重力浓密导水通道分布与细观渗流规律

浓密床层导水通道分布特征及通道内部的细观渗流机制是影响全尾砂重力浓密效果的关键因素。利用连续浓密试验与CT扫描技术相结合的方法研究剪切作用对床层孔隙分布特征的影响，将扫描结果导入COMSOL软件进行床层内部液体逆向渗流规律模拟，揭示剪切作用对排水过程的影响机理。结果表明：在给料浓度为10%，絮凝剂浓度为0.01%时，无/有剪切作用下连续浓密平均浓度分别为50.10%和55.82%；内部孔隙率分别为49.90%和44.18%。无/有剪切作用下导水通道数量分别为6和2，剪切作用使导水通道的数量降低了66.7%；流出通道数分别为6和1，流出通道数量降低了83.3%；通道内液体最大渗流速度分别为9.574×10^-6 m/s和2.592×10^-6 m/s，出口最大流速分别为5.372×10^-6 m/s和1.468×10^-6 m/s；孔隙表面最大压力值随着液体逆向渗流逐渐降低。剪切前导水通道呈开放连通状态，排水后孔隙体积减小，导水通道闭合，床层浓度进一步提高。导水通道数量的降低说明剪切作用实现了床层的强化排水，为膏体材料的制备奠定基础。

Flow Channel Distribution and Mesoscopic Seepage Rule of Unclassified-tailings in Gravity Thickening Processing

With the expanding scale of mining exploration and mining，and the increasingly serious environmental problems associated with mining，abandoned tailings and mined-out areas have become major hazards in mine safety construction.The traditional low concentration tailings surface accumulation treatment will not only cause land pollution，but also be eroded by rainwater，aggravate the cracking of tailings reservoir，and there are hidden dangers of dam break.Paste filling technology is a green tailings disposal technology，which can not only save land resources，but also protect the ecological environment by disposing of abandoned tailings.The research results show that the strength of tailings filling body is positively correlated with slurry concentration in a certain range.Therefore，by increasing the concentration of tailings filling slurry，the amount of cement can be greatly reduced，and the cost of tailings disposal can be reduced.The key links of paste filling technology of unclassified-tailings are concentrated dehydration of fine tailings and paste preparation.Distribution characteristics of diversion channel in dense bed and micro-seepage mechanism in channel are key factors affecting gravity concentration effect of unclassified-tailings.The raw material of the unclassified-tailings comes from vanadium iron ore flotation tailings.The flocculation settling and shearing experiments of the unclassified-tailings were carried out on a self-developed intelligent small continuous densification test platform.The effect of shearing on the pore distribution characteristics of the bed was studied by combining the continuous densification test with CT scanning technology.The rotation of the scraper at the bottom of the thickener breaks the static balance between particles and water，connects the pore and discharges the closed water to form a high concentration underflow. Samples were obtained by in-situ sampling-quick freezing-freeze drying process for CT scanning test.The image results obtained by CT scanning were segmented，denoised and binary processed by ImageJ image processing software.Then the results were imported into COMSOL Multiphysics software to simulate the law of reverse seepage of liquid in the bed.Finally，the influence of shear on drainage process was revealed by analysis. The results show that when the feed concentration is 10% and the flocculant concentration is 0.01%，the average concentration is 50.10% wt and 55.82% wt respectively under the continuous dense condition without/with shearing，and the internal porosity is 49.90% and 44.18% respectively，indicating that shearing can increase the average concentration while reducing the internal porosity.The number of diversion channels under non-shearing and shearing is 6 and 2 respectively.The shearing reduces the number of diversion channels by 66.7%，the number of outflow channels by 6 and 1 respectively，and the number of outflow channels by 83.3%.The maximum seepage velocity of the liquid in the channel is 9.574×10^-6 m/s and 2.592×10^-6 m/s respectively，and the maximum flow velocity at the outlet is 5.372×10^-6 m/s and 1.468×10^-6 m/s respectively.The maximum pressure on the pore surface decreases gradually with the reverse seepage of the liquid.Before shearing，the channel is open and connected.After shearing drainage，the pore volume decreases，the channel closes，and the bed concentration increases further.Adding shear action can increase the concentration of tailings and decrease the porosity of tailings，which has a great impact on the channel.The enhanced drainage mechanism under the shear condition studied in this paper will provide theoretical support for the dense dewatering of tailings mortar and lay a foundation for the preparation of high-concentration tailings mortar.