Electricity + Control March 2015

TEMPERATURE MEASUREMENT

o Mining is one of South Africa’s largest electricity consumers. o Deep level gold and platinum mines in South Africa require extensive cooling and ventilation. o Cooling and ventilation consume 40% of a mine’s electricity.

project approach delivers results that are greater than current ad hoc and uncoordinated implementations of projects.

take note

Conclusion This study listed all the sections of a mine cooling and ventilation system as well as all the associated energy and cost saving strategies. Each strategy was then analysed with regard to their yearly monetary savings, potential risks and other factors. The risk of each strategy was evaluated against service delivery, production, EHS, as well as overhead cost. Other factors (PAI) that were considered were the purchasing of new equipment, upgrading existing equipment, expanding the mine network and monitoring, implementation time, downtime and the interaction with other projects. However, not all the projects could be implemented and the best combination of projects was determined. This combination was then sequenced by taking into account the factors mentioned above and looking at the project implementation steps. A simplified simulation was then used to determine the power usage of a mine’s cooling and ventilation system. The annual cost was calculated using the simula- tion model and Eskom’s tariff structure. These results showed that R30 M can be saved annually. In conclusion this study has shown that, by following the sequenced combination proposed, the maximum savings on all the systems will be realised. References [ 1] Eskom. 2011 annual report. Eskom, Johannesburg, South Africa. [Online]. Available at: [Ac- cessed on 23 June 2012]. [2] Neser H. 2008. Energy savings through the automatic control of underground compressed air demand (dissertation). [3] Swanepoel JA. Modelling for integrated energy optimisation in ce- ment production. Proceedings of the 10th International Conference on the Industrial and Commercial Use of Energy. August 2013. [4] Le Roux, H. Energy consumption reduction challenge. MiningWeekly 11(43):30, November 2005. [5] Schutte AJ. An integrated energy efficiency strategy for deep mine ventilation and refrigeration”, thesis submitted in partial fulfilment of the requirements for the degree PhD in Mechanical Engineering, North West University, May 2014. [6] Swart C. Target electricity cost-saving report, with emphasis on clear water pump system. HVAC International, July 2003. [7] Calitz J. Research and implementation of a load reduction system for a mine refrigeration system. (Dissertation submitted November 2006, North-West University. [8] Wilson RW, Bluhm SJ, Funnel RC, Smith H. Surface bulk air cooler concepts producing ultra-cold air and utilising thermal storage. Pro- Acknowledgement This study was presented at the 2014 ICUE conference held in Cape Town.

ceedings of Managing the Basics. The Mine Ventilation Society of South Africa, Pretoria. 2003. [9] Bluhm SJ, et al. Generation and distribution of refrigeration for ultra- deep mining: New challenges and insights. Proceedings of the Frigair 2000, Gallagher Estate. South African Institute of Refrigeration and Air-conditioning (SAIRAC). Johannesburg, 2000. [10] Le Roux D. Energy recovery from incoming high pressure cold water in deep level mines. Proceedings of the 9th International Conference on the Industrial and Commercial Use of Energy. CPUT. Stellenbosch, South Africa. August 2012. [11] Botha, A. Optimising the demand of a mine water reticulation system to reduce electricity consumption. (Dissertation. North-West Univer- sity. November 2010. [12] Schutte AJ, Maré P, Kleingeld M. Improved utilisation and energy performance of a mine cooling system through control of auxiliary systems. 10th International Conference on the Industrial and Com- mercial Use of Energy. CPUT, Cape Town, South Africa. August 2013. [13] Kukard WC. Research on reducing cost of underground ventilation networks in South Africanmines. Dissertation. NorthWest University. Nov. 2006. [14] Pooe T, Marx WM, Du Plessis J, Janse van Rensburg J, Van den Berg L. Main fan energy management – actual savings achieved. 9th International Mine Ventilation Congress. New Delhi. 2009. [15] Fourie JW. Power savings by impeller replacements for main fan stations in the South African gold mining industry. 9 th Conference on the Industrial and Commercial Use of Energy. Stellenbosch. August 2012. [16] Booysen W, Van Rensburg JF. Load management on closed loop underground fridge plants and the effects on working conditions. 10th International Conference on the Industrial and Commercial Use of Energy. CPUT, Cape Town. August 2013.

Dr Abrie Schutte is a registered professional engineer and holds a PhD in mechanical engineering from the North- West University. He is enrolled for post-doctoral studies with CRCED Pretoria, a division of North-West University. He is also a consultant to HVAC International. and TEMM International. Enquiries: Email aschutte@rems2.com Prof Marius Kleingeld is a registered professional engi- neer and holds a PhD in mechanical engineering. He is a lecturer at the CRCED Pretoria, a division of North-West University. He is also a consultant to HVAC International and TEMM International. Enquiries: Email mkleingeld@rems2.com

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