Mine ventilation characterisation through simulations

Abstract

The profitability of the mining industry is contingent on the industry's ability to improve upon the status quo of operational efficiency. If the archaic operating methods of mines are altered to embrace and incorporate simulation technologies, improvements can be made to, inter alia, characterisation, energy usage, planning, equipment utilisation, operational efficiency and profitability. Literature indicated a need for improved characterisation of complex mining systems. Mine ventilation is a complex mining system, which is crucial for safe and legal mining operations. Considering that this system may represent up to half of a mine's energy consumption, there is large scope for improved characterisation through simulations. Literature indicated that there was a need for improved mine ventilation characterisation through simulations for operational changes. This study therefore focussed on developing a framework to characterise mine ventilation systems incorporating simulations. Through the use of the simulations, mine ventilation characterisation was improved for the quantification of energy efficiency projects, life-of-mine planning and the use of medium-voltage variable speed drives as part of ventilation-on-demand applications. As a result, four individual articles were compiled that contribute towards the framework. This framework lead to improved mine ventilation characterisation through simulations combining novel methods, models and variable speed drive technologies. In Article I (Appendix A), a scalable, step-by-step method was developed to evaluate and optimise mine ventilation networks through simulations. This method was implemented on a case study mine ventilation network with the study validation resulting in an energy saving of 23% per annum. The most feasible operational change as indicated by the novel method has been active for a period of 18 months. The total energy savings measured for this period amounted to 13.32 GWh, resulting in an energy cost saving of US0.7 million. In Article II (Appendix B), a novel economic quantification model was developed to quantify and monetise the true financial benefit of mine ventilation energy efficiency projects. The study validation showed that the feasibility of implementing energy efficiency projects on mine ventilation networks increases with the inclusion of non-energy benefits. The total financial benefit including non-energy benefits proved to be three times more and reduced payback periods by 33% on average when compared with traditional energy saving quantification models. In Article III (Appendix C), a novel integrated simulation planning method was developed for primary access and ventilation network life-of-mine planning. This method was implemented successfully on a case study mining complex. The most feasible planning scenario, as indicated by the method, resulted in a cost avoidance of US28.8 million. This amounted to an average cost avoidance percentage of 27%. In Article IV (Appendix D), characterisation and simulation were used to evaluate the use of medium-voltage variable speed drives as part of ventilation-on-demand applications. This was done on ten South African mine ventilation networks. The large-scale assessment was conducted for two ventilation-on-demand applications, namely, static and dynamic. The assessment results indicated that it was economically viable to implement both applications, which resulted in a combined estimated cost saving of US11.57 million with a payback period of nine months. This would result in an estimated energy saving of 53% on the ventilation network. The final remarks of the thesis indicated that mine ventilation characterisation can be improved through simulations, thus contributing to the current field of knowledge.