某全尾砂膏体流变参数测量及其流变模型优化

Measurement of Rheological Parameters for the Whole-tailing Paste and Optimization of the Rheological Models

全尾砂膏体在管道输送设计时需要选取合适的非牛顿流变模型。但全尾砂膏体在进行流变参数测取实验时,其颗粒种类、粒度分布及其内部结构不能保证在每一份测量试验下均相同,故全尾砂膏体流变参数测量重复率较低且其流变模型选择不够精确,直接影响了管道输送阻力值的大小。针对以上问题,基于全尾砂膏体在恒定剪切速率下存在剪切应力松弛的特性,待其剪切流动达到"等结构"状态后再测量相应的剪切应力-剪切速率关系。基于多次测量均值法降低流变参数测量的随机误差,并通过模型多参数依次拟合法求取最适宜的流变模型。研究结果表明,本次实验最优模型为Bingham伪塑性体模型,最优流变参数为幂律指数n=0.7,屈服应力82.24 Pa,稠度系数4.941 Pa·s,各样品组之间流变参数拟合差异较小,实验方案能够获取较精确的流变模型。

The whole-tailing paste needs to select the appropriate non-Newtonian rheological models when designing the pipeline transportation. However,factors of the particles type,the particles size distribution and its internal structures can＇ t be guaranteed the same in each test on the whole-tailing paste rheological parameters,so the repeatability of the whole-tailing paste rheological parameters is low and the selection of rheological model is not precise enough,which will affect the resistance of the pipeline transportation. In view of the above problems,and based on the fact that the whole-tailing paste has the property of shear stress relaxation at a constant shear rate, the corresponding relationship of shear stress-shear rate would be measured af-ter the shear flow reaches the ＂iso-structure＂ state. Based on the multiple mean measurement method,the random error of the rheological parameters can be reduced,and the optimal rheological model is obtained by the method of multi-parameters se-quential fitting. The results show that the optimal model for this experiment is Bingham pseudoplastic model,and the optimal rheological parameters are power law index n= 0. 7,yield stress 82. 24 Pa and consistency coefficient 4. 941 Pa·s. There is little difference in the fitting of the rheological parameters among the sample groups,and a more accurate rheological model can be obtained by the experimental scheme.