The Mantoverde Sulphide Development Project is a brownfield copper project located in Chile’s Atacama region. Image courtesy of Mitsubishi Materials Corporation.
The project will expand the current Mantoverde open-pit oxide operations. Image courtesy of RobSt/Shutterstock.
The Mantoverde Sulphide Development Project is estimated to produce 110,000t of copper a year. Image courtesy of Funtay/Shutterstock.

The Mantoverde Sulphide Development Project is a brownfield copper project in the Atacama region of Chile. The project is being developed by Mantos Copper through its fully owned subsidiary, Mantoverde.

It involves the construction of a copper concentrator and associated facilities at the Mantoverde site and the expansion of the existing Mantoverde oxide operation, which became operational 25 years ago.

The project is expected to extend the mining life of the Mantoverde operation up to 2041. The expansion will allow Mantoverde to produce 110,000t of copper and 33,000oz of gold a year from 2023 to 2030.

The project is estimated to create up to 1,500 jobs during construction and 200 permanent jobs, upon the start of operations.

Mantoverde Sulphide Development Project location and geology

The Mantoverde Sulphide Development Project is approximately 56km south-east of Chanaral and approximately 40km east of Bahía de Flamenco.

The Mantoverde deposit lies within the north-south trending Atacama Fault Zone (AFZ), a major fault zone and arc-parallel wrench fault system in coastal Chile. The primary host rocks are characterised by Jurassic and early-Cretaceous andesitic flows and breccias intruded by coeval, early-Cretaceous granitoids of the Chilean Coastal Batholith.

Mineralisation and reserves

The copper-gold mineralisation at Mantoverde is primarily hosted in specularite-dominated tabular breccia bodies, pipes, and stockwork bodies. All are associated brittle faults belonging to AFZ. The three breccia units at the Chilean copper cathode mine lie parallel to the 12km-long Mantoverde fault for up to 1,500m.

The mineral reserves at the Mantoverde Sulphide Development Project are estimated to be 2.1 million tonnes (Mt) of contained copper, while resources are estimated to be 5.7Mt of contained copper.

Mining methods at Mantoverde

The Mantoverde mining operation uses conventional open-pit mining methods involving drill, blast, load, and haul operations. The mining of high-grade ore is supported by a fleet of 90t trucks and 14m³ front loaders, while low-grade and sterile ore is transferred by 140t trucks and 17m³ front loaders.

The mining operations are currently carried out at Mantoverde, Kuroki, Franko and Celso pits with the Mantoverde pit serving as the main pit of the operation. Approximately 17Mt of material will be deposited in the sterile dumps at the Celso-Mantoruso and Mantoverde pits prior to the start of operations for the expansion.

The slope angle design is envisaged at approximately 85º while the inter-ramp angles will vary from 50º to 60º.

Mineral processing of the Mantoverde Sulphide Development Project

The Mantoverde Sulphide Development Project is estimated to produce approximately 74,000t of copper concentrate a year.

The project will expand the processing operations at Celso-Mantoruso and Mantoverde through the construction of a concentrator plant with a capacity of 13 million tonnes per annum (Mtpa) with a daily average of 33,000t and a maximum of 35,600t, during the useful life of the project.

The current processing operations involve the crushing of the run of mine (ROM) ore in primary, secondary and tertiary crushers. The crushed ore is fed into agglomerators to condition the minerals by adding sulfuric acid and a refining solution.

The agglomerated mineral undergoes leaching in a dynamic heap system and solvent extraction (SX) to extract copper from the rich leaching solution. The extracted solution is then washed and stripped and passed into an Electro-gain (EX) plant where copper present in the enriched electrolyte is deposited into cathodes which is the final product.

Infrastructure facilities

The project area is accessible by access roads, from the north via Highway 5 Norte / C-13 / C-209 and from the south by routes 5 Norte / C-261 / C-225.

The power requirement for the current operations at the mine is supplied from the Diego de Almagro substation in Diego de Almagro city.

A potable water supply is obtained from a treatment plant of drinking water (PTAP) in the mine-plant area.

Financing for Mantoverde Sulphide Development Project

An $847m project financing package for the Mantoverde Sulphide Development Project was closed in February 2021. It includes a $520m senior secured amortising project debt facility for 12 years and a $51.6m senior secured closure bonding facility for ten years.

Mantoverde raised $275m through equity proceeds from a transaction which allows Mitsubishi Materials Corporation (MMC) to acquire a 30% interest in Mantoverde. MMC will also provide a $60m cost overrun facility in lieu of an additional offtake of copper concentrate from the project.

Contractors involved in Mantoverde Sulphide Development Project

A turnkey engineering, procurement and construction (EPC) contract was awarded to Australia’s Ausenco to undertake the construction of the sulphide development project.

SG Americas Securities and Scotiabank provided financial advice to Mantos Copper in the financing package deal while Simmons & Simmons and Baker McKenzie served as legal advisers.

Norton Rose Fulbright and Estudio Prieto Abogados provided legal advisory services to the lending syndicate.