7/29/2019 018 Campos

1/1

CORFOsuea emprende crece Una Operacin de Xstrata Copper

LOMAS BAYAS

The Lomas Bayas ore deposit, owned byXstrata Copper, is located 120 km northeast of

Antofagasta city, in the Atacama Desert ofnorthern Chile.

Mineral Formula

C opp er P i tch Mn O( OH) C uS iO2nH2O

Copper Wad CuOMnO27H2O

Criptomelano K2-x(Mn3+, Mn4+)8O16XH2O

Birnesita (K0.33Mn3.9+7O147H2O).

Crednerita CuMnO2

The wad mineralization occurs associated tobreccias bodies with intense phyllic or

supergene alteration assemblages, closelyrelated to copper species such as atacamite,

chrysocolla, chalcanthite, antlerite, andbrochantite, whereas the most common gangeminerals related are limonites, quartz and caolin.

Copper wad is a generic mining term for a mixtureof Cu-bearing manganese oxyhydrates that pose

recovery problems as it is refractory to acidleaching or has very slow kinetics dissolution in the

conventional hydrometallurgical systems. Theseoperational problems has led to the fact that

copper wad traditionally has not been incorporatedin the resources estimation and are left untreated

in the leached pads or labeled as waste material.Recent operational innovation on the efficient

treatment of cooper wad imposes new challengeson the identification of areas mineralized with

these Cu-bearing materials.

Eduardo Campos*, Mara Soledad Bembow*, Andrea Rojas Pardo*, Giorgo Realini*, David Vega*** Departamento de Ciencias Geolgicas, Universidad Catlica del Norte, Antofagasta, Chile.

** Compaa Minera Xstrata Lomas Bayas, Chile.

Hipogene sulfides includes chalcopyrite, pyrite,bornite, digenite and molibdenite. The primaryore is deeply modified by supergene processes

that generate secondary enriched zonescharacterized by chalcocite-covellite mineral

association. Oxidation of secondary and primaryore originates supergene copper oxide minerals

such as antlerite, brochantite, chalcanthite,

chrysocolla, atacamite, and copper wad.

Lixiviado Oxidos Mixto Secundario Primario Sondajes con Copper Wad

THE LOMAS BAYAS DEPOSIT THE COPPER WAD

The copper wad from Lomas Bayas can becharacterized as anCu-bearing manganese-iron oxide,

showing a variable chemical compositioncomposed mainly of manganese (more that 50%), iron (around 5 %) and copper (between 4and 10 %), other minor elements are Si, K, Al,

and Zn.

amorphous or poorlycrystalline

The ore body has been defined as a low grade(0.30 % Cu) porphyry type deposit, being theworld lowest grade copper mine in production

today.

Brecha

Andacollo

Porfido

Lomas

Brecha

Tirana

S

Aluvio

Superficie 24Marzo 2009

Brecha

Andacollo

Porfido

Lomas

Brecha

Tirana

S

Aluvio

Brecha

Andacollo

Porfido

Lomas

Brecha

Tirana

S

Aluvio

Superficie 24Marzo 2009

This research was supported by CORFO-INNOVA proyect

COD: 08CM01-09, Xstrata Lomas Bayas and the UniversidadCatlica del Norte.