不同颗粒组成与质量分数矿料的尾矿浆流变特征与模型研究

Rheological Characteristics and Modeling of Tailings Dam Outflows with Various Particle Compositions and Mass Fractions

尾矿库溃坝下泄物的流变特征,是分析溃坝时空演化过程及致灾范围的重要前提.本文配制了6组不同粗细颗粒比和6组不同质量分数矿料的尾矿浆,采用旋转式流变仪分析颗粒组成和矿料质量分数对尾矿浆流变特征的影响,并分别基于屈服伪塑性流变模型和Bingham流变模型拟合得到尾矿浆的流变模型.结果表明:40%矿料质量分数条件下,尾矿浆体中细颗粒含量较少时,浆体的黏度和屈服应力很小,且剪应力随剪切速率的增大变化不大,呈现牛顿流体特征;随着细颗粒含量的增大,浆体逐渐转变成非牛顿流体,黏度和屈服应力迅速增加,并逐渐趋于指数增大趋势,剪应力也随剪切速率的增大迅速增大;矿料质量分数为10%或40%且细颗粒含量较低的尾矿浆体由于水和尾矿砂分离,其性质类似于挟砂水流,可以通过牛顿流体模型进行描述;细颗粒含量较高的尾矿浆体,Bingham模型和屈服伪塑性流体模型均可以对其流变特征进行描述.

The rheological characteristics of tailings are exceedingly complex,playing a critical role in analyzing the temporal and spatial progression as well as the disaster scope of tailings dam failures.In this study,six groups of tailings slurries with varying particle size ratios and another six groups with different mass fractions are prepared.The impact of particle composition and slurry concentration on the rheological properties of tailings are analyzed,using a rotational rheometer.Subsequently,rheological models of the tailings slurry based on the Bingham fluid model and the yield pseudoplastic fluid model respectively are fitted.The findings indicate that when the tailings slurry contains fewer fine particles under the condition of 40%particle mass fraction,the viscosity and yield stress of the slurry are low.Additionally,shear stress exhibits minimal variation with an increase in shear rate,demonstrating Newtonian fluid characteristics.As the content of fine particles escalates,the slurry undergoes a transformation into a non-Newtonian fluid,resulting in a rapid increase in viscosity and yield stress.This increase approaches an exponential growth,and shear stress also rises sharply with an increasing shear rate.Tailings slurry with 10%particle mass fraction or 40%particle mass fraction with a lower content of fine particles displays properties akin to sand-carrying water flow due to the separation of water and tailings sand.This can be suitably described using the Newtonian fluid model.Conversely,tailings slurry with a higher content of fine particles can be characterized by its rheological properties using both the Bingham model and the yield pseudoplastic fluid model.