A near optimal hoist scheduling for deep level mine rock winders

This paper presents a near optimal hoist scheduling for rock winders found in South African deep level mines in the context of demand-side management and time-of-use (TOU) tariffs. The scheduling uses a combination of discrete dynamic and constrained linear integer programming to address the primary problem of achieving a set hoist target at a minimum energy cost. A methodology adapted from the branch-and-bound method is presented for obtaining an integer solution. The hoist schedule states the number of hoists to complete during each half hour over a d-day period, ensuring minimal hoisting during expensive high demand periods thereby improving the load factor of the utility. The energy cost savings of the near-optimal TOU schedule is illustrated in comparison with a flat rate tariff schedule energy cost.