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

矿物加工是一个独特的复杂领域，因为所涉及的矿物具有异质性。这是一个重要的工业领域，因为生产冶金过程的原料是至关重要的，因为它是有效和可行地回收金属的合适品位的原料。不同矿体中矿物的自然变异性，以及矿物分布、结构和组合的差异，意味着选矿设备不能普遍优化；这导致矿物回收率较差，因为矿体与设备“匹配”。在选矿厂，生物可利用重金属的释放通常与直径小于20-30微米的细粒矿物的回收率较差有关。这些生物可利用的金属可以积累在环境中，对生态系统产生公认的有害影响。这方面的例子很容易在西南部的历史过程中看到，例如在比索河和碳谷。离心力强化的重力分离是回收含有重金属的细小颗粒的既定技术。尽管如此，人们对这些设备内分离的确切物理手段知之甚少，而且历史上只开发了针对设备和矿石的经验模型，因此使用有限。计算能力的不断提高导致了通过计算流体力学和离散元素建模的组合来模拟复杂的两相和三相动态系统的能力，包括人口稠密的颗粒系统。这项技术非常适合于研究设备中物质流动的基本物理，该设备旨在通过密度的差异来分离颗粒。预计这一模型最终将改进设备设计和制造，从而使设备能够‘安装’到矿体的特定要求。这将减少采矿对环境的影响，并降低每吨生产金属的能源成本。预计该项目将结合以下几个方面：-计算模拟与实验验证-制造工艺设备-调查减少重金属在环境中的释放对化学、生物和环境的影响。成功候选人的角色将涵盖多个领域，反映该项目的跨学科方法。学生将使用CFD-DEM相结合的方法生成离心式分离设备的模型，并通过实验验证这些模型。这项工作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，根据他们的建模对工艺设备进行更改，并对这些更改进行实验测试。建模也将被用来确定设备材料的理想粒度分布(PSD)，学生将通过与当地咨询公司的联系来研究使用专门的超细粉碎设备生产材料的方法。测试材料将从目前正在运营的矿山和历史上的矿山废物地点收集。学生将评估材料对环境的影响，并量化加工后的影响变化。

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.