The paper presents a method of calculating the Net Smelter Return or Revenue (NSR) formula for copper ore mines based on heuristic models of functional relationships between concentration of metals in ore and copper concentrates, the operational efficiency, and the metal prices in the global markets. A method has been proposed to identify these relationships as well as a way of estimating their parameters. The NSR optimization calculations have been performed for the data coming from the mining and smelting practise of KGHM Polska Miedź S.A., which demonstrate its practical usefulness in assessing the efficiency of production based on the current quality of ore, the efficiency of its beneficiation, and the market prices of metals.