The traditional pitshell optimization lerch grossman or pseudoflow is still. The first phase results in practical npvbased schedules. Over the past 35 years the determination of optimum openpits has been one of the most. The algorithm uses block dependencies to determine which blocks must be mined out. Different genetic procedures are applied to increase robustness, namely two typologies of admissible mutations for the elite subpopulation subjected to zooming and mutation and reproduction for the remaining individuals. Application of lerchsgrossman pit optimization to the. Pit shells are mostly independent of the schedule and stockpiling, and therefore can be done independently of an advanced simo optimization. Cost effectiveness of openpit hard rock ore mining.
Pit optimisation using solid modelling and the lerchs. A comparison of conventional and direct block scheduling. Technical apers introduction academic research over the past three decades has focused on using the lerchsgrossmann algorithm as a mechanism for solving more general openpit mine scheduling problems. Pit optimization optimization problem that selects the blocks to be mined to maximize pit value while respecting all constraints two most popular methods. Pdf pseudoflow, new life for lerchsgrossmann pit optimisation. The three phases of mine planning ensure that the highest value is received from an open cut mine based on a practical schedule, which is implemented in a shorter planning horizon. Also in order to show this effect, an illustration example is discussed. In industry, two widely popular methodologies to calculate the ultimatepit limits are lerchs and grossmann and floating cone.
The technique, founded in 3dimensional graph theory, relies on a regular system of blocks which defines the value profit, loss and type ore, waste of material contained in the blocks. Graph g with dummy node x0 and arcs added from the dummy node x0 to all other nodes. In the optimization of open pit mine design, the lerchsgrossmann algorithm is the industry standard, although network flow algorithms are also well suited, efficient, and known. An approximate pit optimization methodology suited to the. Nevada net proceeds tax and open pit optimization stope. Red dog mine closure and reclamation plan supporting.
Pseudoflow, new life for lerchsgrossmann pit optimisation. I keep finding articles and abstracts that talk about lerchsgrossman pit optimisation that say that the algorithm has a basis in graph theory. Anyone know the theory behind lerchsgrossman pit optimisation. The ranked pits were then amalgamated into logical pushbacks based on mining constraints. It is clear from the definition of our graph g that a graph closure in g represents a physically feasible pit, if not, then a block not in our closure violating the slope. The most basic will include geological and mining constraints, mining and processing costs, pit slopes and product prices. There are well established algorithms for this including lerchsgrossmann, pushrelabel and pseudo. Lerchs grossman method 1 applied mathematics algorithms.
Hochbaum, anna chen, 2000 performance analysis and best implementations of old and new algorithms for the. Revised ultimate pit designs were developed utilizing a lerch grossmantime value of money pit optimization routine. In the manual method, a simple optimization of economic pit depth was usually carried out by hand calculator or. A genetic algorithm with zooming for the determination of. Lerch grossman is the name of a modeling approach for solving openpit optimization. A critical appraisal of the whittle 3d openpit mine optimization. Algorithms to solve the open pit optimization problem have been developed by many researchers.
Lerchs and grossmann 1 developed an open pit optimization algorithm based on graph theory. Due to the uncertainty in the operational and economic conditions in the mining industry there is a need to. I havent seen any articles that elaborate on what part of graph theory was used to create this optimisation method. Most of the available packages rely on lerch grossman algorithms defining economic limits to underpin the time optimization algorithms, a condition that is not met in zulti north. Lerchsgrossmann algorithm with variable slope angles. It was developed in 1965 and implemented in the 1980s by jeff whittle.
Resources are stated within a lerch grossman optimized pit shell using the following parameters. The original paper published by lerchsgrossmann about determination of. Over the past 35 years the determination of optimum openpits has been one of. These ultimate pits were then subdivided into pit shells by ranking the pits generated by the optimization routine by net present value. I can now show you how we use them to optpen pit mining and approximate a good ug mine plan as well. Technical apers is openpit production inside mines. Conventional pit optimization calculates optimal pit limits from a block model of economic values and precedence rules for pit slopes. A method of precise pit optimization commonly used in the mining industry is the lerch grossmann method. To begin, the decision to go open pit or ug very much. Finally, step 4 can be assisted by optimization tools, but it mainly depends on the ability of the planner to make the best choices. Mathematical optimization models and methods for open pit mining. Openpit mining is an operation in which blocks from the ground are dug to extract the ore contained in them, and in this process a deeper and deeper pit is formed until the mining operation ends. Is there a role for lerchsgrossman optimization in. Determination of the optimum cutoff grade considering.
Lerchsgrossmann algorithm with variable slope angles request. Stochastic open pit design with a network flow algorithm. Selection the optimal open pit contour and phase determining both softwares are based on the lerch grossman optimization algorithm. Case studies in open pit design using lerchsgrossman pit optimization. The ultimate pit limit problem has been efficiently solved using the. Planning and design procedure of an open pit mining project just can be started after ultimate pit determination. Lerchs and grossmann 1965 are the first to put forward a method to. Lerch grossman ultimate pit surface modeling medium term pushbacks ramps schedule monthday plan equipment level asbuilt surface current machine locations and activities operational decisionsupport machine guidance current face fleet management survey reconciliation drillblastloadhaul crushprocess smeltrefine metal planning metal. Pseudoflow models give new life to the lerchsgrossmann pit optimisation muir 2004.
Performance analysis and best implementations of old and. The stochastic version of the conventional deterministic network flow algorithm is based on the use of multiple simulated realizations of the ore deposit, thus. Ore bodies are conceived to be divided into units that have significance to the mining engineer, can be geometrically described e. Request pdf lerchsgrossmann algorithm with variable slope angles one of the most.
Designxl is developed by primethought software solutions. Abstractone of the most important design factors in open pit mining is determination of the optimal pit. Using the lerchsgrossman algorithm during open pit mine design designxl duration. The only input required is tonnage and grade information. Open pit mining is an operation in which blocks from the ground are dug to extract the ore contained in them, and in this process a deeper and deeper pit is formed until the mining operation ends.
Definition of the optimum open pit, whether an intermediate phase or final design, will be sensitive to many factors. Using the lerchsgrossman algorithm during open pit mine. A genetic algorithm ga with nested zooming strategy is proposed for the determination of the optimal open pit mine design. Client manager primethought software recommended for you. Pits may be redesigned many times during the life of a mine in response to changes in design parameters as more information is obtained and to changes in the values of technical and economic parameters.
The basic cad tools of envisage are found in the first four menu items. An approximate pit optimization methodology suited to the slm framework miguel a. The proposed system is compatible with traditional approaches to economic analysis in open pit planning, and with emerging best practices to manage technical and economic uncertainty, improve project optimization, and develop robust mine plans. Optimisation, mining, stripping ratio, block model, pit design 1 introduction. The implementation of the algorithm with respect to block models is considered. Further, the pit optimization method must be highly efficient to allow for an effective sensitivity analysis. Mathematical optimization models and methods for openpit mining.
The application of the three dimensional lerchsgrossmann pit optimization procedure to this task is described for a range. Pdf the lerchsgrossmann lg algorithm 1965 has been used for over thirty years for the optimum design of open pit mines. This package utilized the lerchgrossman algorithm for the first time in a commercial. Lerchs grossman method 1 free download as powerpoint presentation. Determination of ultimate pit limits in open mines using. Secondly, an underlying assumption of open pit optimization techniques is that the mining method has a reasonable degree of flexibility. In 1986 the whittle 3d openpit optimization package was launched by whittle.
Cuba and clayton deutsch the calculation of the ultimatepit is the base for designing the lifeofmine plan of a surface mining project. A back to basics approach to mining strategy formulation. The differences in the figures are due to the widening of the pit bottom and the creation of a ramp and berms in the designed pit, which resulted in the addition of some waste, ore loss and dilution. This is a video showing how to get an optimum pit shell in designxl given the blockmodel and the face angle constraints. Optimized open pit mine design, pushbacks and the gap. Notice we are not dealing here with the design of pit phases, which are also strongly user dependent.
Abstractone of the most important design factors in openpit mining is determination of the optimal pit. Pit limit optimization open pit design is a computerbused implementation of an algorithm that is applied to a three dimensional block model of an ore body, i. Pit optimiser provides different options for financial, optimisation and analysis scenarios. This knowledge base has transferred to industry and, at present, a number of software firms, including geovia, maptek and minemax, offer produc.
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