Development and Validation of a Waste Rock Dumping Optimisation

Abstract

Waste rock dumps represent among the largest remnant structures of open pit mining operations. They can absorb a large proportion of the mine’s operating costs, and can be costly to rehabilitate. Poor design, construction and rehabilitation of waste rock dumps can produce a major safety risk and environmental hazard. There are many examples worldwide where poor design and construction of waste rock dumps have resulted in failures causing considerable loss of life and widespread damage, or have resulted in erosion and seepage that have led to severe environmental pollution. The proper design and scheduling of waste rock dumps and haul routes can significantly reduce costs, minimise the possibility of failures, and avoid harming the environment. The first part of the paper discusses waste rock haulage costs and waste rock dump design in open pit mining operations, and describes the development and application of a waste rock dump scheduling model using the Operations Research technique of Mixed Integer Programming (MIP). The model focuses on minimising the haulage cost for each block of waste rock taken from the open pit and placed in the dump. Allowance is also made for the selective placement of benign and reactive waste rock, based on an open pit block model that delineates the different rock types. The second part of the paper employs the proposed model to schedule real mine site data. The findings and applicability of the methods are discussed in the final section of the paper. Additional