Open-pit mine design optimization applies the Lerchs–Grossmann (LG) algorithm or Whittle software to maximize economic value by identifying the optimal ultimate pit limits based on a block model(Open Pit Optimization, 2024).
Developed in 1965, the Lerchs–Grossmann (LG) algorithm represents an open-pit mine as a graph in which blocks are treated as nodes assigned net values based on ore revenue minus mining costs. It identifies the maximum closure—a connected group of economically viable blocks that satisfy slope constraints—using dynamic programming in two dimensions or graph theory in three dimensions, and generates a series of nested pit shells to support pushback planning as commodity price assumptions change(Lerchs-Grossmann Open-Pit Design Method | PDF | Vertex (Graph Theory) | Graph Theory, n.d.).
Whittle applies the Lerchs–Grossmann method, or its pseudoflow variants, within software platforms such as GEOVIA to generate a range of pit shells by varying economic parameters like metal prices and costs. Engineers then evaluate and select the most suitable shells based on factors such as net present value (NPV), stripping ratios, and sensitivity analyses, before refining the designs further to account for geotechnical and operational constraints for practical implementation(Application of Surpac and Whittle Software in Open Pit Optimisation and Design, n.d.).
Reference:
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Application of Surpac and Whittle Software in Open Pit Optimisation and Design. (n.d.). Retrieved April 11, 2026, from https://www.academia.edu/13042201/Application_of_Surpac_and_Whittle_Software_in_Open_Pit_Optimisation_and_Design
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Lerchs-Grossmann Open-Pit Design Method | PDF | Vertex (Graph Theory) | Graph Theory. (n.d.). Scribd. Retrieved April 11, 2026, from https://www.scribd.com/document/461414933/H-Lerchs-and-I-F-Grossmann-1965-Optimum-design-of-open-pit-mines-pdf
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Open Pit Optimization: From Pit Shells to Final Contour Design. (2024, December 23). K-MINE. https://k-mine.com/technical-articles/mastering-open-pit-optimization/
