The mineral supply chain in an ideal open-pit mining operation constitutes a set of sequential stages including a surface mine or an open-pit, a processing plant and a refinery or market. Cut-off grade defines the flow of materials from the mine to subsequent stages within this mineral supply chain. This underlines the significance of cut-off grades in establishing the economic viability of an operation. However, only heuristic methods are available for defining the cut-off grade policy for complex mineral resources (orebodies) that constitute multiple economic minerals. This article proposes a new mixed integer programming based mathematical model that generates an optimal cut-off grade policy for open-pit mining operations that mine, process and refine or market multiple metal products. An implementation of the new method in three separate case studies reflects better performance (i.e., 24%, 36% and 27% higher net present value) against available heuristics.

理想的露天采矿作业中的矿物供应链包括一系列连续的阶段，包括露天矿或露天矿，加工厂和精炼厂或市场。边界品位定义了从矿山到该矿物供应链中后续阶段的物料流。这突显了在建立运营的经济可行性时，临界级别的重要性。但是，只有启发式方法可用于定义构成多种经济矿物的复杂矿物资源（矿体）的品位分级政策。本文提出了一种基于混合整数规划的新数学模型，该模型为露天矿开采，生产，加工和精炼或销售多种金属产品生成了最佳的品位等级政策。