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Excavating the First Underground Gyratory Crusher at the Deep Mill Level Zone Mine, PT Freeport Indonesia


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Author E Hernandez, W Kusumohastuti and I Agustian


PT Freeport Indonesia is completing the first underground gyratory crusher excavation at their Deep Mill Level Zone (DMLZ) mine located in the mountains of Jayawijaya, District of West Papua, Indonesia. DMLZ is an underground block cave mine with an expected output of 80 000 t/d and a scheduled production start in 2015.

In order to deliver crushed ore to the mill through the existing conveyor belt, the DMLZ block cave mine will construct two 1000 kW 1.6 × 2.3 m gyratory crushers with their own respective ore flow conveying systems underground. Each crusher is composed of top, middle, and bottom chambers with an ore bin. This system includes a series of high capacity conveyors approximately 5 km in length including transfer stations and support facilities.

The development methodology required a combination of lateral development by jumbo drilling machines and vertical development by mechanised raise climbers (MRC) due to the complexity of the chamber design.

This paper will discuss the project scope, design and development methodology, ground conditions, innovative survey controls, and the challenges faced due to the remote location.


Hernandez, E, Kusumohastuti, W and Agustian, I, 2014.
Excavating the first underground Gyratory Crusher at the Deep Mill Level Zone
mine, PT Freeport Indonesia, in Proceedings 12th AusIMM Underground
Operators’ Conference 2014
, pp 43–50 (The Australasian Institute of Mining and Metallurgy: Melbourne).