Capstone Copper Chile has formally opened the Mantoverde Development Project (MVDP) which involves some US$870 million of investment and will extend the useful life of Mantoverde for another 20 years as well as tripling the mine’s annual copper production to 120,000 t.
It will also have a sustainable focus with 100% use of desalinated water and 50% renewable energy by 2025. And it will generate more than 1,000 jobs with around 70% of them being hired locally. “This project represents the future potential of the new medium-sized mining in the country,” said Capstone Copper ‘s CEO, John MacKenzie, at the opening ceremony, which was also attended by representatives of one of the initiative’s top partners, Mitsubishi Materials Corporation, and authorities such as the Minister of Mining, Aurora Williams. the Governor of Atacama, Miguel Vargas and the ambassadors of Canada, Australia and Japan. Capstone said it is the beginning of a more modern, efficient and sustainable mining for the region.
The MVDP has increased production from approximately 35,000 t/y of copper (cathodes only) in 2022 to a run-rate of approximately 120,000 t/y of copper in H2 2024. A new concentrator plant is treating sulphide material to produce copper concentrate while oxide ores continue to be treated in the existing SX-EW plant. Mining continues to be conventional open pit operations using truck-and-shovel technology. The MVDP consists of processing sulphide ores in a concentrator with a capacity of 12.3 Mt per year. Construction was completed in late 2023. MVDP has progressed under a lump-sum turn-key engineering, procurement and construction (EPC) contract with Ausenco.
Mantoverde currently has four active leach systems, two at capacity and two receiving ore. The dynamic leach pad (DLP) is an on/off pad measuring 700 m x 900 m and capable of treating 11 Mt per year of crushed ore under the current leach conditions. The South Dump II (SDII) leach pad is a run-of-mine leach system with the capability of expansion as needed. Ore is delivered to one of the two leaching operations based on copper and carbonate grades. Typically, higher copper and lower carbonate grade ores are sent to the dynamic leach pad and the balance to South Dump II.
DLP ore is delivered from the pit to a primary crusher and then conveyed to a coarse ore stockpile. The ore is then fed by conveyor to a vibrating screen, with the oversize reporting to a secondary standard cone crusher. The crusher product is then conveyed to five surge bins, which feed five tertiary screens. The screen oversize feeds the five tertiary crushers. The final crushed ore product is stored in two bins that feed the two parallel agglomeration drums. Agglomerated ore is transported by a system of overland conveyors, grasshopper and tripper conveyors to a stacker which places the ore on the dynamic leach pads in a 7 m high lift. Sulphuric acid and raffinate are added at the agglomeration drum. The spent leach residue is unloaded and placed in a dedicated leached waste dump via bucket wheel and overland conveyor. The unloading is augmented by shovel and truck as required.
Leaching is accomplished by irrigating the ore with a dilute sulphuric acid solution using either intermediate leach solution (ILS) or raffinate. The use of intermediate leach solutions allows for the pregnant leach solution grade to be maximized. Solution leaving the DLP flows into a PLS or ILS pond based on the copper grade. The PLS pond feeds the SX circuit, and the ILS pond is used for irrigation.
The dynamic heap leach pad operation is complemented by a run-of-mine dump leaching process. Material for dump leaching is deposited directly on the pad via truck dumping without crushing. Lift heights of 20 m are employed. The ore is initially exposed to a high acid cure followed by a leach cycle consisting of intermediate leach solution (ILS) and raffinate. Like the DLP, the SDII uses an ILS solution to maximise the PLS grade. The PLS from SDII PLS pond reports to a common PLS pond close to the solvent extraction (SX) plant.
Run of mine material is delivered to the primary crusher (1400 x 2100 TS) by 240 t Komatsu 830E dump trucks which discharge ore into the feed hopper (capacity of 330 t). Crushed product discharges into a 330-t capacity intermediate hopper. An apron feeder is located under this hopper to transfer the material to a conveyor and then to the coarse ore stockpile. The coarse ore stockpile has a live capacity of 16,150 t (dry) and two apron feeders, located under the coarse ore stockpile, to reclaim ore. The apron feeders discharge ore to a transfer conveyor which feeds a single 34’ x 20’ (nominal) 14 MW semi-autogenous-grinding mill (SAG) fitted with a variable frequency drive (VFD). The SAG product is screened via a trommel, and the oversize (pebbles) is recycled to the SAG mill feed belt via two conveyors. The undersize from the trommel discharges into the primary cyclone feed box, which is connected to two variable speed horizontal centrifugal pumps, one operating and one stand-by. The pumps send the slurry to a hydrocyclone cluster (with 7 operating and 2 stand-by) which classifies the mill discharge by size.
Hydrocyclone underflow (coarse) reports to a single 24’ x 42’ (nominal) 14 MW ball mill with a VFD. Ball mill product is screened via a trommel with oversize ore and ball scats discharging to a reclaim bunker at grade. Trommel undersize reports back to the primary cyclone feed box. The hydrocyclone overflow (fine) flows by gravity through a pipe to the flotation process. The grinding circuit targeted feed size is a P80 of 180 μm.
The rougher flotation circuit comprises seven conventional tank cells (300 m3 each). Rougher concentrate is pumped to the regrind stage which has a vertical mill, 14.9’ x 45’ with a 932-kW motor, in closed circuit with a hydrocyclone cluster. The overflow from the regrind hydrocyclone cluster, target P80 of 38 μm, discharges by gravity to the feed box of the first cleaning stage.
The first stage of cleaning consists of two conventional tank cells (130 m3 each). Tailings from the first cleaner stage feeds directly to the scavenger circuit, consisting of three conventional cells (130 m3 each). Concentrate from the scavengers joins the rougher concentrate in the regrind circuit. The rougher and scavenger tailings are sent to the tailings thickener. Concentrate produced in the first cleaning stage is discharged to a transfer hopper and pumped to the second cleaning stage (two 4.75 m diameter flotation column cells).
Concentrate from the second cleaners flows by gravity to a transfer hopper and is pumped to the third and final cleaning stage (one 4.75 m diameter column flotation cell). The tailings from the third cleaning stage discharges by gravity to the second cleaning stage feed hopper. The tailings from the second cleaning stage discharges to a transfer box and is pumped back to the first cleaning stage.
The copper concentrate from the final cleaner flows by gravity to a 20 m diameter high rate concentrate thickener. From the thickener, two peristaltic pumps, one operating and one stand-by, transfer the thickened concentrate to an agitated tank. This tank has one centrifugal pump with variable speed and feeds the 108 m2 filter press. Dewatered filter cake (target 9% moisture) discharges to grade and is loaded by a front-end loader into trucks which transports the concentrate from the plant to a port for shipment. The filtrate from the filter discharges into a transfer box, from where it is pumped back to the concentrate thickener. Process water recovered from the concentrate thickener overflow is sent to a dedicated process water tank and distributed back to the plant by three pumps, two operating in parallel and one stand-by.
The combined final tailings, formed by the rougher tailings and the scavenger tailings, flows by gravity to a transfer box which feeds a 55 m diameter high-rate tailings thickener. Water recovered from the tailing thickener is sent to the process water tank. Thickened tailings (underflow) are pumped 3.3 km to a Sand Plant consisting of a hydrocyclone cluster and a slimes thickener. The hydrocyclone classifies the tailings to produce a coarse sand (underflow) which is pumped to the tailings storage facility (TSF) and used to build the dam wall. The hydrocyclone fines (overflow) is sent to the 55 m diameter high-rate slimes thickener for water recovery. The thickened underflow is pumped and deposited in the TSF and the thickener overflow water recovered returned to the main process water tank for distribution to the sulphide concentrator.
Capstone is currently analysing the next expansion of the sulphide concentrator. The company has identified that the desalination plant capacity and major components of the comminution and flotation circuits of the Mantoverde Development Project are capable of sustaining average annual throughput of up to 45,000 t per day with no major capital equipment upgrades. Capstone continues to work with Ausenco’s engineering team to develop the Optimized Mantoverde Development Project (MVDP Optimized or MV-O), including evaluating the costs and timelines of debottlenecking the minor components of the plant to meet the potential throughput target. The Feasibility Study is on track for completion late in H1 2024.
The MVDP had transitioned from a hydraulic shovel operation to the usage of electric rope shovels to increase the mine capacity, and this strategy is maintained for the MV-O plan. The MV-O mine plan was developed by Capstone staff in 2024. The plan focuses on two main areas, Celso–Mantoruso, and Mantoverde. The MV-O flotation throughput considers expansion of the MVDP plant capacity, resulting in an average throughput of 16.4 Mt/y of flotation ore (45,000 t/d) from Q1 2026 to 2049, with a ramp-up period that assumes a production rate of 4.8 Mt in 2024 and 12.3 Mt in 2025.
The mine plan considers the continuity of the leach mineral processing as part of sulphides pits until 2037. Ore treatment in the heap process considers an average annual treatment of 10.9 Mt between 2025 and 2030, while the dump process will process up to 15.0 Mt/y. The mining schedule requires an average mine extraction of 155 Mt moved per year from 2025 to 2037. This includes heap leach feed requiring rehandle. The mine movement decreases after 2037 until the mining operations are completed in 2043. The process plant continues to operate through to 2049, treating low-grade stockpile material.
The loading fleet consists of Cat 994K 22 m3 front-end loaders, Komatsu 4100XPC 44 m3 electric cable shovels, and Komatsu PC5500 26 m3 hydraulic shovels. The hauling fleet consists mainly of Komatsu 830E trucks, and a fleet of Cat 785s to re-handle oxide material. A peak of 65 trucks will be required between 2032 and 2037 for MV-O. Oxide phases use Atlas Copco (Epiroc) DM50 and Cat MD6310 drills. The sulphide-dominant phases use taller benches and larger drills are required.
