A1 - Cetin Erhan
PB - Komitet Zrównoważonej Gospodarki Surowcami Mineralnymi PAN
PB - Instytut Gospodarki Surowcami Mineralnymi i Energią PAN
N2 - 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 density 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 will 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.
VL - vol. 34
IS - No 2
KW - cut-off grades
KW - optimization
KW - grid search
KW - rehabilitation cost
KW - depletion rate
T1 - Assessment of costs in cut-off grades optimizationby using grid search method