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RADOMIRO TOMIC COPPER MINE, CHILE
Radomiro Tomic is the first mine to have been entirely developed by the Chilean state copper-mining company, Codelco. Located at 3,000m above sea level in the Atacama Desert of northern Chile, this new mining and hydrometallurgical operation is 4km from the Chuquicamata mine and smelter. Development was approved in 1995, started in 1996 and was essentially completed in 1997. The initial target capacity was 150,000t/y of copper cathodes but optimisation during construction raised the rating to 180,000t/y by the commissioning date. Prime contractor LX Ltda (Bechtel and ARA in joint venture) completed work early, below the budgeted $641 million. Recovering copper by heap leaching and electrowinning, Radimiro Tomic was inaugurated in 1998.
In 1999 Codelco contracted Kvaerner Metals to increase the plant capacity to 250,000t/y of cathode at a cost of $220 million. This expansion was completed in 2001.
Codelco initially created a new Radomiro Tomic Division with a streamlined organisation to manage the facility. During 2002, the corporation decided to amalgamate Chuquicamata and RT as one division - Codelco Norte - and developed a consolidated resource exploitation plan for the deposits in this area. About 460 people work at Radimiro Tomic.
ANACONDA GEOLOGY AND RESOURCES
Discovered in 1952 by Anaconda, which then owned Chuquicamata, the Radimiro Tomic deposit lies beneath approximately 100m of alluvial material and extends over 5km x 1.5km x 200m. During 1993-94, Codelco upgraded the geodata, establishing a resource base for the operation comprising 802Mt of oxide ore grading 0.59% copper, with 1,600Mt of refractory ore.
Hosted in porphyry intruded into Triassic and Palaeozoic rocks, the economic mineralisation is differentiated by mineral assemblage into an Upper Oxide unit - with 40% by volume of atacamite, 31% copper clays and minor chrysocolla and copper wad - and the Lower unit with 70% atacamite and minor copper clays and chrysocolla. The orebody resulted from the oxidation of a secondary sulphide enrichment blanket.
The conventional open pit strips at a 1.5:1 waste-to-ore ratio using rotary drills, P&H 4100 shovels, a LeTourneau loader, Caterpillar 793B and Komatsu 330st-capacity trucks. An FFE Minerals gyratory primary crusher near the pit rim supplies coarse ore, which travels to the main processing area via a 9,615t/h Krupp conveyor. The expansion added tertiary cone crushing (SRP Hydrocones) to the secondary Symons cone. Conveyors take stockpiled ore to pre-treatment and stacking on the racetrack-style heap-leach pads. Leached material is reclaimed by a bucket wheel and is conveyed to the dump area. Rahco and MAN-Takraf supplied the crawler-mounted materials-handling equipment. To handle the expanded production, the conveyor drives were fitted with programmable soft braking systems.
Following acid leaching, the copper is separated from the heap-leach solution by four-stage solvent extraction with Acorga reagents and is fed in solution to the electrowinning tankhouse for recovery as cathodes using sophisticated technology. Four solvent-extraction trains designed and supplied by Outokumpu Engineering (including VSF mixer-settlers, Proscon 2100 NT process control system and OTI 99 titrators) remove the copper. The electrowinning feed and reagent streams are cleaned using molecular sieve coagulators and electrolyte filters designed by Codelco, and by CPT flotation columns. The large and highly automated electrowinning tankhouse was fitted with unique cathode cranes and stripping machines as well as a system of blowers and aerosol chimneys to ventilate the cells. The expansion added 272 cells, two travelling cranes and a cathode washing-stripping machine. Secondary leaching of waste will add 24,000t/y to 28,000t/y of copper to the cathode output.
After start-up, Radomiro Tomic recorded total operating costs of $0.44/lb, producing 162,000t copper in 1998 and 190,100t in 1999. The expansion boosted output to 256,000t/y in 2001 and Codelco hoped to maintain production at around 300,000t/y thereafter. Actual output in 2002 was 297,119t at a cash cost of $0.33/lb.
The cathodes, almost entirely Grade A, are trucked to Antofagasta for shipping.
Rotary blasthole drilling in the open pit.
A P&H 4100 shovel loads Caterpillar 793B haulers in the open pit. Komatsu AC-drive haulers were also added to Radimiro Tomic's truck fleet during the expansion.
MAN-Takraf supplied conveying equipment for handling crushed material both before and after leaching.
A purpose-designed bucket-wheel excavator is used to remove leached ore from the pads once the copper has been extracted.
Solvent-extraction plant fluid streams are cleaned using Codelco-designed equipment.
External view of the electrowinning tankhouse showing the cell ventilation system…
…and inside the tankhouse.
Radimiro Tomic's environmental centre, where Codelco is developing its reclamation planting strategies.
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