Mining in various regions of the world. Air
Mining is the most traditional source of mineral commodities that all countries have found it necessary for enhancing their living standards. Therefore, improvement of the mine productivity has been an important concern in various regions of the world. Air quality in underground mines plays a basic role in mine productivity because the lack of proper air will often lead to lower worker efficiency and decreased productivity and increased accident rates 1. Various elements such as methane, humidity, diesel emissions, blasting fumes, dusts and battery emissions can be found in the air of mine environments 1. Among the mentioned elements, amount of dust produced during mining is a major concern. Dust can cause respiratory disease, contribute to the risk of underground explosion and deteriorate productivity 2. The airflow and dust dispersion are very complex and the standard mine ventilation network analysis is not sufficient to analyze the detailed airflow patterns and dust distribution. Nowadays, with the advancements in computer power, the computational cost of computational fluid dynamics (CFD) modelling has declined and this approach has been popular to the study of mine ventilation and evaluating dust control methods 2-11. In numerical studies 2-11, however general agreement with the experimental data has been reported, discrepancies are still being reported 3 which motivates researchers to conduct more paramedic studies using more comprehensive numerical models for modeling air-dust flow inside underground mines.2. Aims and Objectives Reviewing the literature indicates that CFD has been used in the following mining-related areas 3: ? Mine ventilation airflow ? Spontaneous combustion ? Mine fire ? Methane flow and control ? Gob gas flow ? Inertisation ? Dust dispersion and control ? Minerals processing ? Other applications In this project, we will try to enhance the existing models for numerical capturing of the air-dust flow inside underground mines so that we can obtain results which are more close to the reality. The project can then be extended to the other above-mentioned areas like Methane flow and control.3. Project Methodology To the best knowledge of the author, the fluid flow inside underground mines is an incompressible turbulent multiphase flow which contains different particles. This problem can be formulated using Reynolds-averaged Navier–Stokes (RANS) equations for each phase in which Reynolds stresses are modeled using a type of k–? model. Particles’ movement can also be modeled by Newton’s secondlaw while the particles’ presence show their effect on fluid flow in the context of some source terms in RANS equations. Finite difference method (FDM), Finite volume method (FVM) and Finite Element Method (FEM) are the most traditional methods in CFD to solve RANS equations 12-13. In this project, FVM is used because it has two important advantages which make it popular in commercial CFD packages, such as CFX, FLUENT and PHOENICS. The primary advantage is to satisfy the conservation equations. Secondly, the flexibility of FVM is suitable for treating complex geometries. Particle motion can be modeled using some approaches like distinct element method (DEM). In this study either CFX or OpenFOAM can be used for the simulation because these commercial packages, particularly OpenFOAM which is an open source software, allow us to use a wider range of user defined options and particle–particle interaction models. The developed program might be executed on massively parallel systems to enhance computation speed.4. Significance of the project To design equipment and improve the efficiency and safety of underground mines, understanding the fluid flow is inevitable. It is apparent that analysing fluid flow in underground mines using experimental approaches requires expensive equipment, large amounts of time and understanding of flow in inaccessible areas. Not only can CFD be used to conduct virtual experiments, but it can also be used to better design physical experiments and increase efficiency. Many of today’s mining challenges require both analysis and visualization of fluid flow behavior in complex geometric domains, and comprehensive CFD modeling is a viable tool for this purpose.