Geotechnical investigation and design of leaching heap No. 2, Meydook copper mine, Iran

• The paper uses a comprehensive numerical method to the design of leaching heaps.
• The research demonstrates the application of 3D modeling to practical problems.
• The Meydook copper mine waste rock material has a deformation modulus of 2–3 GPa.
• Interface parameters of 0 MPa cohesion and 15° friction angle assure heap stability.

The main objective of this paper was to investigate the behavior of waste rock material as a foundation for the construction of leaching heaps. In mountainous open pit operations, selection of an appropriate location for dumping waste rock material or building leaching heaps is a major challenge. Meydook copper mine is one of the largest copper operations in Iran. The mine has operated about 2 decades. The current waste rock dump is located 4 km from the operation site but a new proposed dump only 1 km away will be built in a valley to the North of the pit. Construction of leaching heap No. 2 has been on the mine technical department agenda. The main objective of the project is to evaluate the potential for construction of heap No. 2 on a waste dump. Considering the project condition, a 3D analysis of heap major structures including; valley rock foundation, waste dump, and low grade ore was carried out. Five sets of analyses were conducted and the displacement and stress fields were computed. In all analyses conducted, the subsidence profile was determined for the valley base rock and heap foundation (waste dump). The analyses showed that the maximum settlement at the heap base would be only 4–5 cm so the waste dump provides a safe and reliable base for the heap construction. A sensitivity analysis of heap mechanical parameters was also conducted. The results showed that if the friction angle of heap material was reduced below 25°, the heap walls became unstable and the heap geometry would need to be redesigned.