Caeté Complex (Pilar Gold Mine, Roça Grande Mine)
Pilar Mine and Roça Grande Mine
The Caeté Mining Complex (CCA) is composed of two underground mines (Roça Grande Mine and Pilar Mine) that utilize a combination of mechanized cut and fill and sub-level stope mining methods. Ore produced from these mines is transported to the 2,200 tonnes per day gravity, flotation and CIL treatment of flotation concentrate, processing plant adjacent to the Roça Grande mine. Ore from the Pilar mine is trucked a total distance of approximately 40 kilometres by road to the Caeté plant.
The Caeté mining complex, which includes the Pilar and Roça Grande mines and the Caeté Plant, is located in the state of Minas Gerais, Brazil, 50 kilometers east of the city of Belo Horizonte.
|Caeté Complex Consolidated Mine Statistics|
|2 Underground Mines|
|Roça Grande Mine & Pilar Mine Mining Methods:
|Pilar ore, shipped to RG, 50kms|
|Capacity - 2,200 tpd|
|Pilar Mine Statistics|
|Underground Operation - ore shipped to RG mill, 50kms|
|Mining Method - Sub-Level open stoping|
|Capacity - 2,000 tpd|
* Will be published with year end financials in March
Pilar Deposit - Geology
The Pilar deposit is hosted by the basal units of the Nova Lima Group. The rocks in the region of the mine are comprised of tholeiitic basalts and komatiite flows of the Ouro Fino and Morro Vermelho Units, along with their intrusive equivalents. To the west, these basal units are in fault contact with mica-quartz schists, chlorite-quartz schists, chlorite-sericite schists, and chemical and clastic sedimentary rocks of the Santa Quitéria Unit. The chemical sedimentary rocks include chert and BIF. To the east, the units are in fault contact with migmatites and granitic gneisses of the Bação Complex that form the basement sequence.
On the mine property, all rock units strike in a northeasterly direction. The regional strike of the units changes to a southeasterly direction to the south of the mine property. Regional mapping has found that the foliations mostly dip steeply to the southeast. The regional-scale thrust faults also strike in a northeasterly direction and dip steeply to the southeast on the mine property.
On the property scale, at least three different orientations of faults are recognized. The earliest fault is the northeasterly-striking regional-scale thrust fault that forms the contact between the Santa Quitéria Unit and the Ouro Fino and Morro Vermelho Units. This thrust fault cross-cuts and terminates a more northerly set of faults that have a strike of approximately 020° and dip steeply to the east. The third set of faults are oriented in an east-west orientation and have subvertical dips. The displacement along these faults has been observed in underground exposures to be in the order of one to two metres.
The host rocks of the mine have been affected by at least one period of folding. Structural mapping on the property has shown that the orientation of the fold axes dip approximately 45° to the southeast (azimuth 135°).
The mineralization at the Pilar Mine is hosted by a number of the host rock units including the BIFs along with mafic schists and talc-chlorite schists. Gold mineralization is associated with sulphide mineralization consisting of arsenopyrite and pyrrhotite. Quartz veins and veinlets can also be present, however, the presence of quartz is not a prerequisite for higher gold values. The sulphide minerals occur mostly as disseminations in the host rock, however, semi- massive to massive concentrations are seen locally over a few tens of centimetres. Quartz veins are typically less than one metre in width.
ROÇA GRANDE MINE - CCA COMPLEX
|Roça Grande Mine Statistics|
|Underground Operation - ore milled on site at RG mill operation|
|Mining Method - Mechanized cut & fill|
|Capacity - 2,000 tpd|
ROÇA GRANDE DEPOSIT
The Roça Grande Mine is located in the upper unit of the Nova Lima Group. The dominant rock types found in the mine are a mixed assemblage of meta‐volcanoclastics and meta-tuffs. These are represented by quartz sericite and chlorite schists with variable amounts of carbonate facies BIF, oxide-facie BIF, metacherts, and graphitic schists. The iron formations, chert units, and graphitic schist units are intimately inter-bedded with each other, such that they form an assemblage of chemical and clastic sedimentary units.
Two important BIF horizons are present at the Roça Grande Mine, the North Structure (Structure 1) which hosts the RG01 mineralized body and the South Structure (Structure 2) hosts the RG02, RG03, and RG06 mineralized bodies. The RG07 mineralized body is located immediately in the hanging wall of Structure 1 and is hosted mostly by a quartz vein. The bedding is well defined by the carbonate-facies iron formation and chert found in the BIF horizons, with an overall strike of azimuth 70o to 80o, and dipping approximately 30o to 35o south.
At Roça Grande, gold mineralization is most commonly associated with BIF horizons. In RG01, RG02, RG03, and RG06 mineralized bodies, the gold mineralization is developed roughly parallel to the primary bedding and is related to centimetre-scale bands of massive to disseminated pyrrhotite and arsenopyrite. In many cases, better gold values are located along the hangingwall contact of the iron formation sequence and is hosted by carbonate-facies iron formation. The grades generally decrease towards the footwall where the iron formation becomes more silica-rich. In the RG07 mineralized body, gold is found to be hosted in quartz veins that are contained within a sericite (chlorite) schist associated with an east-west oriented shear zone (Machado 2010).
Pacheca Geophysics Survey