Mining of the Mt Fubilan deposit is carried out with the majority of the ore sourced from the base of a large conical shaped pit. The deeper ore reserves are contained within areas of significant sulphide mineralisation.
Other smaller sections containing ore reserves are located within the pit resource boundary and the ore is blended upon delivery to the primary crusher.
In 2016, about 63 million tonnes (Mt) of combined ore and waste material will be mined, with a total of about 65Mt moved, which includes material re-handling.
The material movement rate has increased post 2012 as part of the Mine Continuation program with bulk waste stripping both on the East and West walls of the pit being a primary focus.
The ore is mined utilising a fleet of loading and haulage units and dumped at the gyratory Crusher (dump pockets). Ore grade control is achieved by blast-hole drilling and sampling to delineate ore and waste using a pre-determined NSRPT (Net Smelter Return per Tonne) cutoff value.
Working parameters at the Ok Tedi Mine include nominal 15m mining benches, 10 per cent grade on ramps, 30m wide haul roads. Pit wall slopes range from 65 degrees to 80 degrees in competent Darai limestone.
Mining uses conventional drill and blast techniques utilising 4, PV 271 Pit Vipers that conduct production drilling at 16m depth bench design (1m sub drill) The D65 drills are used for pre-splitting along competent sections of the high walls to improve stability and design conformance. Blast holes are single primed with wet emulsion bulk explosives.
Ore and overburden is mined utilising 4, 6050 (528 Tonne) Caterpillar Hydraulic Face Shovels and 4, 6030 (296 Tonne) Caterpillar Hydraulic Backhoes. This material is loaded into a fleet of 31, 793FUltra Class Mechanically driven Haul trucks. 7, 789C Haul truck are utilised for ore and over burden removal coupled with 2, 993K Cat loaders. The remainder of the fleet is of Caterpillar origin and complements the main load and haul fleet.
The ore from the mine is crushed in a primary crusher at a nominal 5-6,000 tph (tonnes per hour) and conveyed to a primary ore stockpile.
The primary ore is ground in two SAG mill circuits each with two associated five-metre diameter ball mills. The final product is less than 180 micron. The finely ground material is treated in two mineral floatation circuits to extract the copper, gold and silver as a copper concentrate. (Click here to read more about Mill Operations)
The concentrate is piped as slurry to Kiunga where it is dried and the final product shipped to export markets. (Click here to read more about Kiunga Operations)
The residue material following metal product removal is retreated in a separate floatation plant to extract pyrite (iron disulphide). The pyrite slurry is piped to Bige for burial in subaqueous storage facilities and the residual sand is disposed of as tailings to the river system (Click here to read more about Bige Operations).
The primary waste dump destinations are the ‘erodible’ dumps which are strictly managed and monitored. Only remote control dozing is authorized on erodible dumps using the CAT D11T dozers.
Production (Ore/Waste) and Manpower
- Mine budget for 2016: 62,582,000 tonnes (total mined), 17,589,000 tonnes (Ore)
- 44,992,000 tonnes (Waste)
- Manpower – approximately 340 mining personnel on site at any time
Underground Drive Development
In the later parts of 2009, method statements and scope of works were developed to cut two new portals in the Mt Fubilan Pit for exploration drilling. These two new Exploration Adits named Paris and Gold Coast were completed in 2011.
The initial drainage tunnel works were completed in 2011, and continued into 2012 developing a 200 metre near vertical escape-way and additional drives for geotechnical and resource diamond drilling.
2014 and 2015 saw the extension of the underground workings on two fronts;
- The Exploration Drive South as a means to provide dewatering of the Harvey Creek Cave system; and
- The extension of workings to the North West to conduct geotechnical drilling linked to the West Wall cutback.
- Development of an incline to provide a fourth dewatering shaft to cater for drainage of the Fubilan Open Pit. Due to recent events in the Centre Pit it is unlikely that this shaft will be installed.
With the completion of the drainage incline the underground section was put on Care and Maintenance. No development work is planned for the foreseeable future and current underground operations focus on ensuring the drainage tunnel continues to provide for drainage of the Open Pit.
Machinery & Equipment
All mining machinery is owned by OTML and maintained by the OTML Mobile Maintenance department. As part of the Contractor to Owner operate and maintain transition program, ownership and maintenance of the shovels and excavators transitioned to OTML in June 2014.Mine Maintenance have in 2016 taken ownership of the Bige maintenance operations.
The Mining Business unit maintain and operate a fleet of Caterpillar equipment, numbering 196 in total. The main fleet consists of the following machinery:
4 X 6050 Face Shovels, 4 X 6030 Backhoes, 4 X PV271 Pit Vipers, 2 X D65 pre-split drills, 31X 793F Haul Trucks, 7 x 789C Haul Trucks, 11 X D11R/T Dozers, 3 X D10T Dozers, 4 X 16M Graders, 1 X 16H Grader, 2 X 993K Loaders, 5 x 777 C/G Haul Trucks and Service trucks 3 X 834H Wheel dozers, plus smaller mining equipment utilised for day to day mining activities.
The Mine uses the Modular PTX (Masterlink54) Dispatch fleet management system to optimise fleet and material movements. The Modular Dispatch mining system is used for truck / shovel fleet monitoring and management.
A recently installed Tolaps tyre monitoring system from Klinge has also been installed which is an on-line management system for haul-truck tyres. It monitors tyre heat and operational feedback is instantaneous OTML have successfully implemented and integrated the SafeMine – collision avoidance system (CAS) to safely manage interaction between heavy equipment and light vehicles operating within the mine. The mine operation is managed under approved Safe Work Procedures and operating guidelines to ensure people and equipment are operating safely.
Stockpiles, Competent & Erodible Dumps and Waste Disposal
All dumps are monitored by the OTML Geotechnical Department. Erodible dumps are located at Taranaki, Vancouver, Warama, Harvey Creek and Top Moscow. These dumps cater for the majority of the waste dumping. The ROM Stockpile (Run-of-Mine) capacity is 20,000t. This is classed as a surge stockpile rather than being part of a planned stockpiling strategy.