Marimaca is an open-pit copper mining project located in Antofagasta Province, Chile. It is considered to be one of the biggest copper oxide discoveries in northern Chile in the last decade. Coro Mining is the owner and operator of the project.
A definitive feasibility study (DFS) for the project was completed in June 2018, according to which the Marimaca mine is expected to produce 10,000 tonnes (t) of copper a year over an estimated mine life of 12 years.
The initial capital investment in the project is estimated to be £26.5m ($35m), while production is expected to be commenced by the end of 2023.
Marimaca location, geology, and mineralisation
The Marimaca copper project area is located approximately 45km north of Antofagasta and 25km east of the port of Mejillones.
The deposit forms a small portion of the 300km² exploration licence held by Coro Mining. It lies in the Mesozoic Coastal Copper Belt of Chile, along the Antofagasta Fault Zone that extends 1,000km along the coast.
The mineralisation at Marimaca is found hosted in fractured monzodiorite, breccias, veinlets, and stockworks.
The width of the mineralised zones varies between 450m and 100m, while the thickness is up to 250m.
Cupper reserves at Marimaca
The proven and probable ore reserves at Marimaca copper project are estimated to be 24.6Mt grading 0.80% copper (Cu). The mine is estimated to contain 434 million pounds (Mlbs) of copper in proven and probable reserves.
Coro Mining announced increased measured, indicated, and inferred resources at Marimaca in December 2019, following the completion of the $10.6m Marimaca phase two drilling programme that was started in the last quarter of 2018.
The measured and indicated resources are estimated to be 70.4Mt grading 0.60% Cu, while the inferred resources are estimated to be 43Mt grading 0.52% Cu.
Mining and processing
The open-pit mining method involving load-haul-blast operations will be employed for the Marimaca copper project.
Ore will be extracted using 10m mining benches, while the mining fleet will include front-end loaders and haul trucks.
The run-of-the-mine (ROM) ore will be trucked to the Ivan processing plant, which is located 20km south of Marimaca, to recover copper.
The 10,000 tonnes per annum (tpa) Ivan processing plant was acquired by Coro Mining as part of its acquisition of Minera Rayrock in 2017.
The ore will undergo three-stage crushing and agglomeration, before leaching. Sulphuric acid will be used as reagent for the heap leach process, which will be a 35-days cycle.
The pregnant leach solution (PLS) obtained from the leaching process will undergo solvent extraction and electrowinning for the production of copper cathodes.
The Marimaca project site can be accessed through a 14km-long road connecting the Antofagasta-Tocopilla highway. The Cerro Moreno Airport is located 44km away from the project site.
Electricity for the Ivan processing plant will be supplied through a 69kV transmission line connecting the Pampa substation. The substation at Pampa receives power supply through a 110kV line from the Mejillones power plant.
Water for the Ivan processing plant will be supplied from three existing water wells located 11km away from the plant site, as well as from the local water supplier Empresa Aguas de Antofagasta (ADASA).
Ingeroc, a geotechnical consulting firm based in Chile, performed the geotechnical study for the project, while NCL Ingenieria y Construccion (NCL) provided the mineral resource estimate.