Optimal mill cut-off grade modeling in the mineral deposits via MIP: Haftcheshmeh copper deposit

Cut-off grade play a critical role in defining tonnages mined and processed, average grade of mill feed, cash flows, mine life time, and all major characteristics of a mineral deposit. Simply, the cut-off grade is the lowest grade at which material is considered ore and is processed to create a concentrated commodity product. Essentially, it asserts that the mill cut-off grade is a function of the ore availability and the needs of the mill. The focus of this paper is upon one of these long time-scale decisions: whether to process the extracted material, or to waste it. Consequently, an effort is made for the development of a model for optimization of mill cut-off grade which considers grade blending of mineral deposit. A new mixed integer programming (MIP) model is proposed to deal with this objective and with this model determined the mill cut-off grade of Haftcheshmeh Copper deposit. The results show the obtained mill cutoff grade from proposed model generates the optimum average grade. Therefore, generated net value (NV) from this model is nearer to reality.