Cerro Matoso mine
| Company type | Private |
|---|---|
| Industry | Mining |
| Founded | 1980 |
| Headquarters | Montelíbano , Colombia |
Area served | Colombia |
| Products | Nickel (ferronickel) |
| Owner | South32 (since 2015) |
| Parent | South32 |
The Cerro Matoso mine, situated in northwest Colombia, ranks among the world's largest open-pit ferronickel operations and is the foremost nickel mine in South America, containing Colombia’s most extensive nickel reserves. Managed by Cerro Matoso S.A., the mine's ownership has evolved from Hanna Company and the Instituto de Fomento Industrial (IFI) to Shell, Billiton, BHP, and since 2015, South32. The site has faced accusations of heavy metal contamination affecting nearby indigenous Zenu and Afro-Descendant populations; however, Cerro Matoso contests these allegations, referencing scientific research. In 2018, Colombia’s Constitutional Court initially mandated compensation for affected communities but later partially overturned this ruling due to insufficient direct proof connecting mining activities to the claimed damage.
Geology
Positioned within the municipality of Montelíbano, Córdoba Department, the Cerro Matoso nickel deposit was identified in 1940. It formed atop a Cretaceous peridotitic protolith exposed as an elongated hill spanning approximately . The deposit comprises ten lithostratigraphic layers and contains some of the highest-grade lateritic nickel ore globally. The ore body holds about of nickel metal content.
The hill is composed of holocrystalline rocks including harzburgites and serpentinized dunites, with olivine replaced by serpentinite ranging from 30% to 90%. Profiles from two pits reveal differing nickel concentrations: pit 1 presents a sequence from weakly serpentinized protolith through green saprolite (the primary ore horizon) capped by ferricrete ("canga"), whereas pit 2 lacks green saprolite and exhibits lower, uneconomical nickel grades. Thickness of these units varies but generally extends over several tens of meters. Both pits contain numerous silicate veins bearing nickel-rich garnierite (pimelite), quartz, and chalcedony, with nickel concentrations reaching up to 30–40%.
Mining
Extraction activities at Cerro Matoso commenced in 1980, with nickel production starting in 1982 under joint ownership by the Colombian Government, BHP, and Hanna Mining Company.
Nickel production reached 41,800 tonnes in fiscal year 2008 and stood at 41,000 tonnes in 2014. By 2017, Colombia was ranked 11th worldwide in nickel output, with nickel contributing roughly 9% to the nation’s overall mining revenue.
In May 2015, BHP created South32 as a spin-off entity to oversee Cerro Matoso alongside other non-core assets.
Reserves
Cerro Matoso possesses exploration rights over an area of 77,000 hectares within Colombia’s nickel belt, with mining permits sufficient to sustain current extraction rates for at least two decades. The estimated reserve life of the mine is approximately 42 years based on present production figures. BHP increased operational capacity by installing third and fourth processing lines as well as implementing heap leaching techniques.
According to a 2008 BHP report, proven ore reserves were below 25 million tonnes, while probable reserves ranged between 25 and 70 million tonnes. Data from Colombia’s mining authority UPME in 2007 estimated reserves between 21 and 41 million tonnes. By 2013, Cerro Matoso reported about 108 million tonnes of ore with an average grade of 0.57% nickel. Reserve estimates rose after price forecasts were revised downward, resulting in a reduced laterite ore cut-off grade from 1.0% to 0.6% Ni.
Environment and public health
Concerns have been raised regarding environmental harm attributed to Cerro Matoso’s mining operations; nonetheless, the company disputes these claims by referencing scientific and medical data including routine air and water quality monitoring around the site. Tailings generated contain Fe2O3, nickel oxide, enstatite, alpha-alumina, and Fe3+ clusters embedded within a glassy matrix. Cerro Matoso maintains that tailings are securely contained onsite and are neither corrosive nor reactive nor toxic nor flammable. These conclusions correspond with international research on comparable residues.
Heavy metals such as mercury, zinc, copper, lead, and cadmium have been detected in precipitation samples. Indigenous Zenu communities living nearby have reported health problems including tumors as well as respiratory, skin, eye, and reproductive ailments. A limited study identified arsenic in hair samples from individuals suspected of hydroarsenicism. Despite this, Cerro Matoso denies responsibility for these health issues based on current evidence. A Colombian Regional Environmental Corporation air quality assessment conducted in 2016 reported “optimal conditions” across all pollutant indicators. Air quality monitoring stations certified by Colombia’s National Institute of Hydrology, Meteorology and Environmental Studies provide publicly accessible data confirming acceptable air quality levels near the mine. The company also points out that mercury, lead, copper or arsenic are absent from both the mining deposit and operational processes; some elements detected occur naturally or result from illegal gold mining activities in the region.
A study published in 2015 by the Colombian Institute of Legal Medicine found elevated frequencies of skin lesions and respiratory irritation within a radius of 15 kilometers from Cerro Matoso. Although increased nickel concentrations were observed in blood and urine samples, no correlation was established between them. This study faced criticism for methodological weaknesses by both Colombian and international experts who emphasized other local health determinants such as inadequate access to potable water, use of firewood for cooking, burning of refuse, and unpaved roads. Regional health statistics reveal similar patterns throughout Caribbean communities where Cerro Matoso operates.
In March 2018, Colombia’s Constitutional Court initially ordered Cerro Matoso to compensate local inhabitants; however, this verdict was overturned in September 2018 due to absence of constitutional precedent and insufficient evidence directly linking mining activities to alleged damages.
See also