The effect of controlling main ventilation fan inlet guide vanes for a deep level platinum mine to reduce electrical costs

Abstract

Because of the annual electricity increases from Eskom that are above inflation, and the mining industry that is struggling to survive due to continuous increase in operating cost, the low selling price of precious metals, and past industrial action that took place, there is a need to investigate energy efficiency as well as demand side management methods to reduce the total electricity cost of end users. This can be achieved at a lower cost and in shorter periods of time than the construction of new power stations. In the past there have been many successful demand side management, as well as energy efficiency interventions, specifically in the mining industry. The mining industry in South Africa currently consumes about 14% of the generated electricity and the ventilation usage on deep level mines consumes about 12% of this total. Electricity cost reductions on the ventilation load of a mine are thus important as not many studies have been done on them. However, since safety is of paramount importance on a mine, operational management is reluctant to investigate cost saving methods as it could compromise the environmental underground conditions and hence worker safety. Therefore utmost care should be taken when implementing energy efficiency or demand side management measures. This study focuses on the effect of electricity costs for controlling the main ventilation fans inlet guide vanes of a deep level platinum mine. An actual mine was identified and used for the case study, which demonstrated the impact on costs without affecting the day to day mining operations which were at all times consistent with the environmental standards and regulations of the mine. An actual reduction in power of 13.4% was demonstrated, which would result in an annual cost reduction of about R 1 600 000. With a capital investment cost of R 960 000 and an annual operational cost of R 120 000, a simple payback period of less than a year is achievable. This is expensive but could assist in the survival of the deep level mining industry, specifically the platinum mining industry. As gevolg van die jaarlikse elektrisiteitsverhogings van Eskom wat hoër is as inflasie, en die mynbou industrie wat swaarkry as gevolg van deurlopende verhogings in bedryfs kostes, die laë verkoopsprys van edel metale, en industriële aksie wat plaasgevind het in die verlede, is dit nodig om energie effektiwiteit sowel as aanvraag bestuur metodes te ondersoek om die totale elektrisiteits kostes van eind gebruikers te verlaag. Dit kan bereik word teen ‘n laër koste en in korter periodes van tyd as die bou van nuwe krag stasies. In die verlede was daar vele suksesvolle aanvraags bestuur sowel as energie effektiewe ingrypings, spesifiek in die mynbou industrie. Die mynbou industrie in Suid Afrika verbruik tans sowat 14% van die gegenereerde elektrisiteit en die ventilasie verbruik van diep vlak myne verbruik sowat 12% van die totaal. Elektrisiteits koste vermindering op die ventilasie las van ‘n myn is dus belangrik as gevolg van min studies wat al op die las gedoen is. Omdat veiligheid egter van kardinale belang op ‘n myn is, is operationele bestuur huiwerig om koste besparings geleenthede te ondersoek om rede dit die ondergrondse omgewings kondisies kan beinvloed en dus die die veiligheid van werkers. Daarom moet uiterste sorg geneem word wanneer die uitvoering van energie doeltreffendheid of vraagkant bestuur toegepas word. Hierdie studie fokus op die uitwerking op die koste van elektrisiteit van die beheer van die hoof ventilasie waaiers se inlaat lei wieke van 'n diep vlak platinummyn. ‘n werklike myn was geïdentifiseer en word gebruik vir die gevallestudie, wat die impak op die koste toon sonder dat die dag-tot-dag mynbedrywighede wat te alle tye in ooreenstemming met die standaarde en regulasies van die myn omgewing was. 'n werklike afname in krag van 13,4% word getoon, wat sal lei tot 'n jaarlikse koste vermindering van ongeveer R 1 600 000. Met 'n kapitale belegging koste van R 960 000 en 'n jaarlikse operasionele koste van R 120 000, is 'n eenvoudige terugbetaling tydperk van minder as 'n jaar haalbaar. Dit is duur, maar kan help met die voortbestaan van die diep vlak mynbedryf, spesifiek die platinum mynbedryf.