CFD and CFD-DEM Modelling of enhanced gravity separators to improve understanding and performance

由于涉及矿物的异质性，矿物加工是一个独特复杂的领域。它是一个重要的工业领域，因为它是至关重要的为冶金过程生产原料，适当的品位，有效和可行的回收金属。不同矿体中存在的矿物的自然变化以及矿物分布、结构和组合的变化意味着矿物加工设备不能普遍优化；由于矿体与设备“匹配”，这导致矿物回收率低。生物可利用重金属的释放通常与矿物加工厂中直径在20-30微米以下的细颗粒中的矿物回收不良有关。这些生物可利用的金属可以在环境中积累，对生态系统产生公认的有害影响。这样的例子很容易在西南部看到，由于历史的影响，如在比索河和碳谷。离心力强化重力分离是一种成熟的含重金属细颗粒回收技术。尽管如此，人们对这些装置内部的确切物理分离手段知之甚少，历史上只开发了经验模型，这些模型是设备和矿石特定的，因此用途有限。计算能力的不断提高提高了模拟复杂的两相和三相动态系统的能力，包括通过计算流体动力学和离散元素建模的结合来模拟密集的颗粒系统。这项技术非常适合于研究设计用于通过密度差异分离颗粒的设备中物质流动的基本物理。预计该模型最终将改进设备设计和制造，使设备能够“适应”矿体的特定要求。这将减少采矿对环境的影响，同时也降低每吨生产金属的能源成本。预计该项目将结合以下方面：-计算建模与实验验证-工艺设备制造-调查减少环境中重金属释放的化学，生物和环境影响。成功的候选人的角色将涵盖多个领域，反映项目的跨学科方法。学生将使用组合CFD-DEM方法生成离心分离设备模型，并通过实验验证这些模型。这将主要在埃克塞特大学完成，但也可能涉及到其他研究所的工作。学生将与制造商联系，根据他们的模型对工艺设备进行更改，并对这些更改进行实验测试。建模还将用于确定设备材料的理想粒径分布（PSD），学生将通过与当地咨询公司的联系，使用专业的超细研磨设备，研究使用该PSD生产材料的方法。测试材料将从目前运营的矿山和历史上的矿山废料地点收集。学生将评估材料对环境的影响，并量化加工后影响的变化。

Mineral processing is a uniquely complicated field due to the heterogeneous nature of the minerals involved. It is an important area of industry as it is vital to produce feed material to metallurgical processes which is of suitable grade for efficient and feasible recovery of metals. Natural variability in the minerals present in different orebodies as well as variations in the mineral distribution, textures and associations means that mineral processing equipment cannot be universally optimised; this results in poor recovery of minerals as the orebody is 'fitted' to the equipment.The release of bio-available heavy metals is generally associated with poor recovery of minerals within fine sized particles below 20-30 microns in diameter in mineral processing plants. These bio-available metals can accumulate in the environment with recognised deleterious effects to eco-systems. Examples of this are readily seen in the south-west due to historical processing such as in the Bissoe river and Carbon Valley.Gravity separation enhanced by centrifugal force is an established technique for the recovery of fine particles containing heavy metals. Despite this fact the exact physical means of separation within these devices is poorly understood and historically only empirical models have been developed which are device and ore specific and so of limited use.The continual improvement in computational power has led to increased abilities to simulate complex two and three phase dynamic systems, including densely populated particulate systems through the combination of computational fluid dynamics and discrete element modelling. This technique is ideally suited to investigating the fundamental physics of material flow in equipment designed to separate particles by differences in density. It is anticipated that this modelling will finally enable improved equipment design and manufacture allowing equipment to be 'fitted' to the specific requirements of an orebody. This will reduce the environmental impact of mining but also reduce energy costs per tonne of produced metal.It is anticipated that this project will combine aspects of: - computational modelling alongside experimental validation - manufacture of process equipment - investigations into the chemical, biological and environmental impact of reducing heavy metals release in the environment.The role of the successful candidate will cover a number of areas, reflecting the inter-disciplinary approach of the project. The student will generate models of centrifugal separation equipment using a combined CFD-DEM approach and validate these models experimentally. This will mainly be completed at the University of Exeter but may also involve work at other institutes. The student will liaise with a manufacturer to implement changes to process equipment based on their modelling and test these changes experimentally. Modelling will also be used to determine the ideal particle size distribution (PSD) of material for equipment and the student will investigate means of producing material with this PSD using specialised ultra-fine grinding equipment available through links with local consultancy firms. Test material will be collected from currently operating mines and locations of historic mine waste. The student will assess the environmental impacts of the material and quantify the change in impact after processing.