A OPEN PIT MINING AÇIK OCAK MADENCİLİĞİ

23 rd
A Genetic Algorithm for Pit Limit and Blending Optimization
M. Rahmanpour, M. Osanloo
Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran
ABSTRACT Pit limit is the set of those blocks that are profitable to be exploited by open pit
mining methods. In traditional pit limit optimization techniques, one cannot take into account
the requirements of blending. Some commodities such as iron ore, coal, limestone, and
industrial minerals need to be blended to provide a product that suits consumer’s
requirements. In this paper a combination of genetic and pit design algorithms is used to
determine the pit limit of an open pit mine considering the blending requirements. The
approach uses a self-adaptive differential evolution algorithm (jDE) to selects those blocks
that meet the blend requirements, then modifies the block values, and determines the pit
limits. The resulting pit is a set of those blocks that are profitable to be exploited and blended
by open pit mining.
1 INTRODUCTION
Developing a ‘Geological block model’ is
the first step in computerized mine planning.
In order to construct the Geological block
model of the deposit, the ore deposit or the
orebody is divided into fixed size rectangular
part which is called a ‘block’. The size of
blocks depends on the exploration drilling
pattern, orebody geology and the size of
mining equipment. After determining the
block dimensions, geological characteristics
of each block are assigned using inverse
distance, geostatistical methods, conditional
simulation or other available techniques.
This set of blocks which is based upon level
of geological knowledge and confidence, is
called a ‘Geological block model’. Then,
using economic data (selling price, operating
costs, recoveries, mining and processing
costs), the economic value of each block or
"Block Economic Value" (BEV) will be
calculated. The block model containing the
BEVs is called "Economic block model".
The aim of mine planning is to determine
whether a given set of blocks should be
mined or not, if so, at which time it should be
mined, and once it is mined, how it should
then be processed, to maximize the net
present value of the operation (Dagdelen,
2007).
Determining the final pit outline is the
initial step of mine planning. It determines
the set of blocks with the highest profit,
which could be exploited by open pit mining.
The solution to the final pit limits problem is
usually used to justify the project
economically and it is also a guide to the
mine planner to locate the mine site facilities.
There are many methods introduced by
researchers to determine and optimize the
ultimate pit limit (Newman et al. 2010).
Before applying any of the pit limit
optimization techniques, BEVs should be
calculated through this formula:
BEV = (metal content) × price × recovery
(1)
- processing costs - mining costs
Equation 1 is true when it is applied to
mineral such as gold, copper, and diamond.
When it comes to mineral like iron ore, coal,
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