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Falcondo - Larga, Loma Ortega, Fraser, Peguera, Taina, Guardarraya |
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Dominican Republic |
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Ni
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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All papers now Open Access.
Available as Full Text for direct download or on request. |
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The Falcondo operation of Falconbridge Dominicana, C. por A. is located near Bonao in La Vega Province, some 80 km north of Santo Domingo, the capital of the Dominican Republic.
The Dominican Republic occupies the eastern two thirds of the island of Hispaniola, which is separated from the easternmost tip of Cuba to the west by the 75 km wide Windward Passage.
Falconbridge Dominicana SA (Falcondo), which was established in 1955, was a subsidiary of Falconbridge of Canada. In that year it acquired the Quisqueya Uno Concession, where the Dominican State granted it the rights to explore and exploit nickel. After an extended period of research and pilot plant operation, a commercial plant to produce ferro-nickel in electric furnaces was designed and built near Bonao in 1968. Mining and smelting operations commenced at Falcondo in 1971. The Xstrata acquisition of Falconbridge Canada in 2008 saw the transfer of Falonbridge Dominicana to that company also. Xstrata Resources suspended the Falconbridge operation in 2008 and placed it on care-and-maintenance due to a combination of high petroleum and low nickel prices. The mine was briefly re-opened by Xstrata in 2011, but was put on care-and-maintenance again in 2013 after Xstrata was acquired by Glencore. Falcondo was then sold to Canada’s Americano Nickel Ltd. (owned by a private capital investor) in 2015 who re-opened the first production line in April 2016 with the second line restarting in October 2018. In 2023, Falcondo remains a major ferro-nickel producer.
The operation has a production capacity of 32 000 tpa of contained nickel as ferro-nickel (40% Ni, 60% Fe). To date it has produced approximately 620 000 t of contained Ni since the operation commenced in 1971. Ore is currently (2000) taken from six mining areas, Larga, Loma Ortega, Fraser, Peguera, Taina and Guardarraya. These six areas occur in a string of hills that extend for up to 15 km from the processing plant and lie at between 200 and 600 m above sea level.
The deposits were developed over part of the Loma Caribe peridotite, a 95 km long and 4 to 5 km wide belt of serpentinised ultramafic rocks, mainly harzburgite with subordinate dunite and lherzolite (Lewis et al., 2006; Proenza et al., 2007). Modal proportions, mineral and whole-rock major and trace element compositions of the Loma Caribe peridotite generally coincide with those of abyssal mantle rocks from mid-ocean ridges for the lherzolites, and refractory supra-subduction peridotites for the harzburgites and dunites. Marchesi et al. (2016) conclude from their geochemical study that the geochemical heterogeneity of the Loma Caribe peridotites records shifting conditions of melting during the development of subduction beneath the incipient Greater Antilles palaeo-island arc in the Early Cretaceous. Weathering and lateritisation of these rocks commenced during the Miocene uplift. Repeated uplifts have led to at least four physiographic cycles and the development of a mature lateritic profile. The complete profile is sub-divided from top to bottom into:
Zone A - a chocolate-brown limonite;
Zone B - ochre brown limonite;
Zone C - soft serpentine;
Zone D - hard serpentine;
Zone E - serpentinised peridotite; and
Zone F - ultramafic rock.
The zones A and B correspond to the upper limonite or laterite sensu stricto interval, whilst zones labelled C to E represent the lower saprolitic weathering profile. Zones A and F are rarely ore grade. The rocky ore of Zones D and E account form 40% of the total ore reserves while limonite ore of Zone B is 25% of the reserves. The deposits are classified as hydrous silicate-type, with the main Ni-bearing minerals being hydrated Mg-Ni silicates (serpentine and ‘garnierite’) occurring in the saprolite horizon, particularly in Zone C. In this zone and deeper, crystalline quartz is found, particularly in fracture zones where it is often accompanied by garnierite.
The 'lateritic/saprolite ore' below the overburden averages 7 m in thickness, but varies from a few metres to 40 m.
Ni-sepiolite-falcondoite and other garnierite minerals occur widely in the Falcondo mine (Springer, 1974; Lithgow, 1993). The mineralogy of the ores is highly variable, consisting of lizardite-nepouite, kerolite (talc)-pimelite (willemseite) and sepiolite-falcondoite (Proenza et al., 2008). Garnierites typically occur as vein-filling of fractures in the harder serpentinized peridotites of zones D, E and F, in the lower part of the weathering profile, including the lower part of the saprolite zone, where hard blocks of slightly weathered rock occur (the saprock zone) below the soft saprolite and limonite.
The proven and probable reserve in 1999 was 68 Mt @ 1.18% Ni, with a further 19 Mt @ 1.15% Ni in resource.
The original pre-mining reserve in 1971 was 66 Mt @ 1.58% Ni.
Annual production capacity in 2000 was around 2.7 Mt of ore.
Proven + probable reserves in 2006 were quoted at 54 Mt @ 1.2% Ni.
The bedrock is composed of extensively serpentinised ultra-mafics with 0.15 to 0.35%, but averaging 0.28% Ni, 5.2% Fe, 0.02% Co. Cash operating costs in 1998 were USD 1.82/lb Ni.
The most recent source geological information used to prepare this decription was dated: 2000.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
Falcondo
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Anonymous 1975 - Nickel Mining in the Dominican Republic: in Mining Magazine, December 1975 pp 439-444
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Ferguson B A, Camposano G, Aponte J 1979 - Falconbridge Dominicana, Ore Handling and Preparation: in Evans D J I, Shoemaker R S, Veltman H (Eds), International Laterite Symposium, New Orleans, Louisiana, Feb, 19 to 21, 1979 Soc Mining Engineers, of the AIMM&PE, New York pp 152-168
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Haldemann E G, Buchan R, Blowes J H, Chandler T 1979 - Geology of Lateritic Nickel Deposits, Dominican Republic: in Evans D J I, Shoemaker R S, Veltman H (Eds), International Laterite Symposium, New Orleans, Louisiana, Feb, 19 to 21, 1979 Soc Mining Engineers, of the AIMM&PE, New York 57-84
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Lithgow E W 1993 - Nickel Laterites of Central Dominican Republic. Part 1: Mineralogy and Ore Dressing: in Reddy R G, Weizenbach R N (Eds), The Paul E Queneau International Symposium, Extractive Metallurgy of Copper, Nickel and Cobalt The Minerals, Metals and Materials Society v1 pp 403-425
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Marchesi, C., Garrido, C.J., Proenza, J.A., Hidas, K., Varas-Reus, M.I., Butjosa, L. and Lewis, J.F., 2016 - Geochemical record of subduction initiation in the sub-arc mantle: Insights from the Loma Caribe peridotite (Dominican Republic): in Lithos v.252-253, pp. 1-15. doi.org/10.1016/j.lithos.2016.02.009.
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Tauler, E., Lewis, J.F., Villanova-de-Benavent, Aiglsperger, T., Proenza, J.A., Domenech, C., Gallardo, T., Longo, F. and Gali, S., 2017 - Discovery of Ni-smectite-rich saprolite at Loma Ortega, Falcondo mining district (Dominican Republic): geochemistry and mineralogy of an unusual case of hybrid hydrous Mg silicate - clay silicate type Ni-laterite: in Mineralium Deposita v.52, pp. 1011-1030.
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Tauler, E.T., Proenza, J.A., Gali, S., Lewis, J.F., Labrador, M., Garcia-Romero, E., Saurez, M., Longo, F. and Bloise, G., 2009 - Ni-sepiolite-falcondoite in garnierite mineralization from the Falcondo Ni-laterite deposit, Dominican Republic: in Clay Minerals, v.44., pp. 435-454. doi: 10.1180/claymin.2009.044.4.435.
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Villanova de Benavent, C., Cama, J., Soler, J.M., Domenech, C., Gali, S. and Proenza, J.A., 2022 - Dissolution kinetics of garnierites from the Falcondo Ni-Laterite deposit (Dominican Republic) under acidic conditions: in Applied Geochemistry, v.143, 11p. doi.org/10.1016/j.apgeochem.2022.105357.
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Villanova, C., Proenza, J.A., Gali, S., Garcia-Casco, A., Tauler, E., Lewis, J.F. and Longo, F., 2014 - Garnierites and garnierites: Textures, mineralogy and geochemistry of garnierites in the Falcondo Ni-laterite deposit, Dominican Republic: in Ore Geology Reviews v.58, pp. 91-109. doi.org/10.1016/j.oregeorev.2013.10.008.
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