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    ASSESSMENT OF COSTS IN CUT-OFF GRADES OPTIMIZATION BY USING GRID SEARCH METHOD
    (Polska Akad Nauk, Polish Acad Sciences, Miner & Energy Econ Res Inst Pas, 2018) Cetin, Erhan
    The optimization of cut-off grades is a fundamental issue for metallic ore deposits. The cut-off grade is used to classify the material as ore or waste. Due to the time value of money, in order to achieve the maximum net present value, an optimum schedules of cut-off grades must be used. The depletion rate is the rate of depletion of a mineral deposit. Variable mining costs are to be applied to the really excavated material, as some of the depletion can be left in-situ. Due to access constraints, some of the blocks that have an average grade less than the determined cut-off grade are left in-situ, some of them are excavated and dumped as waste material. Naturally, variable mining costs should be applied to the blocks of a mineral deposit that are actually excavated. The probability density function of an exponential distribution is used to find the portion of the depletion rate over the production rate that is to be left in-situ. As a result, inverse probability densitv function is to be applied as the portion of the depletion rate over the production rate that is to be excavated and dumped. The parts of a mineral deposit that are excavated but w ill be dumped as waste material incur some additional cost of rehabilitation that is to be included in the algorithm of the cut-off grades optimization. This paper describes the general problem of cut-off grades optimization and outlines the further extension of the method including various depletion rates and variable rehabilitation cost. The author introduces the general background of the use of grid search in cut-off grades optimization by using various depletion rates and variable rehabilitation cost. The software developed in this subject is checked by means of a case study.
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    Öğe
    The use of dynamic programming in optimisation of cut-off grades and different depletion rates together with rehabilitation cost
    (Taylor & Francis Ltd, 2025) Cetin, Erhan; Dalgic, Abdurrahman
    Cut-off grade for a mineral deposit is a grade that is used to classify the material as ore or waste. In order to get maximum profit from a mineral deposit, an optimum schedule of cut-off grades must be used. This paper describes the use of dynamic programming in cut-off grades optimisation and further extension of the method regarding with depletion rates and rehabilitation cost. Partial depletion rates have been used for calculating mining and rehabilitation costs. The software developed in this work guarantees the global optimum for different depletion rates.