Determination of the largest pit with the non-negative net profit in the open pit mines

The determination of the Ultimate Pit Limit (UPL) is the first step in the open pit mine planning process. In this stage that parts of the mineral deposit that are economic to mine are determined. There are several mathematical, heuristic and meta-heuristic algorithms to determine UPL. The optimization criterion in these algorithms is maximization of the total profit whilst satisfying the operational requirement of safe wall slopes. In this paper the concept of largest pit with non- negative value is suggested. A mathematical model based on integer programming is then developed to deal with this objective. This model was applied on an iron ore deposit. Results showed that obtained pit with this objective is larger than that of obtained by using net profit maximization and contains more ore, whilst the total net profit of ultimate pit is not negative. This strategy can also increase the life of mine which is in accordance to the sustainable development principals.