Using two-way coupled DEM-SPH to model an industrial scale Stirred Media Detritor
Using two-way coupled DEM-SPH to model an industrial scale Stirred Media Detritor
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DOI：
10.1016/j.mineng.2019.03.001
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发表时间：
2019-06
影响因子：
4.8
通讯作者：
C. B. Ndimande-;P. Cleary;A. Mainza;M. Sinnott
中科院分区：
文献类型：
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作者：
C. B. Ndimande-;P. Cleary;A. Mainza;M. Sinnott
搅拌介质 Detritor (SMD) 是选矿厂中用于细磨和超细研磨应用的研磨设备之一。 SMD 具有垂直方向的八角形外壳，该外壳支撑垂直轴，该垂直轴具有突出的叶轮臂以搅拌装料。人们对这些设备运行期间电荷的运动和物理结构知之甚少。本文探讨了市售 SMD 1100E 中介质和浆料的流动和相互作用，该 SMD 1100E 的电机额定功率为 1100kW。瞬态双向耦合离散元法 (DEM) 和平滑粒子流体动力学 (SPH) 模型用于实现这一目标。 DEM 组件代表完全解析的陶瓷研磨介质，而 SPH 模型代表浆料（水和细饲料和/或产品）。叶轮臂的旋转作用产生的离心力将物料推向磨机壁，形成涡流。搅拌器还产生类似泵送的效果，驱动电荷向上。发现介质紧密地堆积着大约 0.5 的固体分数，而在涡流内部电荷的薄移动表面层中，固体分数减少到大约 0.16。电荷的径向运动被限制在薄的表面层，浆料表现出比介质更高的流动性。介质和浆料的切向速度在磨机壁处和磨机壁附近均为零，并朝着涡流的自由表面增加。在测试条件下，磨机功耗为 985.7kW，约占装机功率的 90%，其中 66% 在介质相互作用中耗散，34% 由浆料中的粘性应力耗散。磨损被发现是 SMD 的主要破损机制。量化了建模中包含浆料相的重要性。
The Stirred Media Detritor (SMD) is one of the milling devices used in concentrators for fine and ultra-fine grinding applications. The SMD has a vertically orientated octagonal shell which supports a vertical shaft that has protruding impeller arms to agitate the charge. There is very little understanding of the motion and physical structure of the charge during operation in these devices. This paper explores the flow and interaction of media and slurry in a commercially available SMD 1100E, which has a motor with a power rating of 1100 kW. A transient two-way coupled Discrete Element Method (DEM) and Smoothed Particle Hydrodynamics (SPH) model is used to achieve this. The DEM component represents the ceramic grinding media which is fully resolved while the SPH model represents the slurry (water and fine feed and/or product). The centrifugal force generated by the rotational action of the impeller arms pushes the charge to the mill wall creating a vortex. The agitator also produces a pumping like effect which drives the charge upwards. The media was found to pack tightly with solid fractions of around 0.5 which decreases to around 0.16 in the thin mobile surface layers of the charge on the inside of the vortex. Radial motion of the charge is restricted to a thin surface layer with the slurry demonstrating higher mobility than the media. The tangential velocity for both the media and the slurry is zero at and near the mill wall and increases towards the free surface of the vortex. For the conditions tested, the mill power draw was 985.7 kW which is ∼90% of installed power, of which 66% is dissipated in media interactions while 34% is dissipated by viscous stresses in the slurry. Abrasion is found to be the dominant breakage mechanism in the SMD. The importance of including the slurry phase in the modelling is quantified.