Toromocho Copper Mine Expansion

The Toromocho copper mine expansion is anticipated to increase the Toromocho open-pit mine’s copper output by 45% to approximately 300,000 tons by 2020. Located in central Peru, approximately 140km east of Lima in the Morococha mining district, Yauli Province, the Toromocho mine was commissioned in June 2015.

The project produced 763,500 tons (t) of copper concentrates, including 182,288t of copper and 5.3 million ounces (Moz) of silver, in 2015.

Construction of the Toromocho copper mine expansion project was started in June 2018, while mining is expected to be commenced in 2020. The estimated $1.35bn expansion project is proposed to be funded through internal working capital and through debt financing. The mine life of the project is expected to be 27 years.

Minera Chinalco Peru, a subsidiary of Aluminum Corp of China (Chinalco), is developing the porphyry copper project. Chinalco acquired the Toromocho mine from Minera Peru Copper (MPC) in 2007.

The expansion is anticipated to increase the daily production capacity of the mine from 117,000 tons per day (tpd) to 170,000tpd. It is expected to produce 75,000 fine metric tons (FMT) of copper a year in addition to creating 3,200 construction and 2,400 operational jobs.

Toromocho mine location, geology, and mineralization

The Toromocho copper mine in Morococha region is located at an altitude from 14,700ft to 16,400ft.

The Morococha area is made up of a sequence of folded paleozoic and mesozoic rocks comprising calcareous sediments in addition to smaller volumes of intercalcated volcanic flows. The rock sequence was subject to multiple intrusions, resulting in the formation of hydrothermal mineralization.

Classified as a copper-moly porphyry system, the copper project features both sediments and contact metamorphic skarns. Secondary enrichment process occurred at the deposit resulted in the formation of a thick zone of mixed chalcocite and chalcopyrite in the upper zones.

The Toromocho deposit comprises a complex group of mineralized veins, veinlets, and stock works. Most of the mineralization is hosted in Jurassic limestones of the Pucara formation as well as in Tertiary intrusives such as diorites, granodiorites, quartz, monzonites, and quartz porphyries.

Toromocho mine reserves

The reserves at Toromocho copper mine are estimated at 1.52 billion tons of ore, grading 0.48% Cu, 0.019% Mo, and 6.88 g/t Ag.

Mining and ore processing at the existing Toromocho copper mine

The Toromocho copper project currently employs conventional open-pit mining method, involving drilling and blasting. Major mining equipment used at the project include four blast hole drills, four cable shovels, 300t haul trucks, six units of DR10 track dozers, four units of 834G wheel dozers, four motor graders, and three Cat 777 frame water trucks.

Ore is processed at the plant using conventional crushing, grinding, and flotation to produce copper and molybdenum concentrates separately.

A heap leach facility is being used to process secondary chalcocite with high volumes of soluble copper, which comprises of high volumes of chalcocite-filled arsenic.

The final concentrate is transported from Ferrovías Central Andina to the port of Callao in a tubular air-tight conveyer and shipped to customers.

The processing plant is installed with a semi-autogenous grinding (SAG) mill, ball mill, and flotation equipment to produce 1,838tpd of copper concentrates. It also includes a separate hydrometallurgical plant to extract 25.1tpd of molybdenum.

Infrastructure facilities at Toromocho copper mine

Power is currently provided by the National Interconnected Electrical Grid through a 220kV substation at Pachachaca.

Water supply for the Toromocho mine is collected from the Kingsmill tunnel.

Contractors involved with the expansion

Fluor was awarded the engineering, procurement, and construction management (EPCM) services contract for the Toromocho expansion project.

Minera Chinalco Peru has engaged Jacobs Engineering Group for preparing the feasibility study report for the Toromocho copper expansion.