黏土胶结充填浆体管道输送特性试验与数值模拟研究

Experimental and numerical simulation for pipeline transportation characteristics of clay paste in consolidation filling

黏土可作为骨料用于矿山胶结充填,浆体的管道输送特性对充填工艺影响很大。利用自溜型浆体管道输送试验系统对体积分数为50%的黏土浆体进行输送试验,在充填倍线为1∶4.89的情况下,黏土浆体在管道中输送良好。对试验系统出浆口处水平管道浆体输送特性进行数值模拟。结果表明,黏土浆体在管道断面流速分布不均匀,层流边界中法向速度梯度大,流速较小时,体积分数分布不均,颗粒易在管道底部堆积,随流速增加,黏土颗粒在管道中均匀分布。黏土颗粒粒度和密度对管道输送基本没有影响,临界速度随着黏土颗粒粒度、密度增大而增大,临界流速与浆体体积分数呈抛物线曲线关系。黏土胶结充填过程中应筛除其中混杂的颗粒粒度和密度较大的杂质,黏土浆体输送速度、体积分数应尽量避开临界速度与体积分数抛物线顶部区域。

The present paper is concerned about our experimental and numerical simulation for pipeline transportation characteristics of clay paste in consolidation filling. As is known, pipeline transportation characteristics of clay paste influence the filling process remarkably. For this purpose, we have introduced the principium, configuration and experimental method of the selfmade gravitytype slurry pipeline transportation experimental system here in this paper, which helps to conduct the transportation experiments of the volume concentration of 50% clay slurry by using the experimental system. Experimental re suits show that the clay paste in the pipeline can be well transported when the filling times line is 1：4.89, though there is very little clay deposit in the pipeline. Seeing the problem, we have carried out our numerical simulation for pipeline transportation characteristics of clay paste by taking a horizontal pipe near the outlet as our research object and choosing the mixture model as a twophase flow model and the RNG x e model as turbulence model. The results indicate that the velocity distribution in the pipeline＇ s section of clay paste turns to be uneven. The fluid moves fastest in the central part of the pipeline and slowest at its wall or nearwall part. A boundary layer would result in near the pipeline wall, and the velocity gradient in the boundary layer tends to be big. When the flow velocity of the paste is low, the vol ume concentration of the solid particles is inhomogeneous and the par ticles accumulate easily at the bottom of the pipe. With the velocity increasing, the clay particles are uniformly distributed in the pipeline, with the particles being no longer accumulated. The clay particle size and its density may not influence the pipeline transporta tion while the critical velocity increases with the clay particle size and density. Since there exists a parabolic curve relationship between the critical velocity and the slurry concentration, the impurities of larger particles and density should be filtered out in the transportation pro cess of mining consolidated filling. Therefore, it is necessary for the clay slurry transportation speed and the volume concentration to keep away from the parabolic top area.