Tampakan Gold Copper Project, Philippines
The Tampakan copper gold mine is located in the Southern Philippines, about 50km north of General Santos City on the island of Mindanao. It is the largest undeveloped copper-gold resource in the South-East Asia Western-Pacific region. The mine is operated by Sagittarius Mines and is owned 62.5% by Xstrata and 37.5% by Indophil. Title to the deposit is held under a financial and technical assistance agreement (FTAA) with the Philippines government, which has agreed to take a pre-determined share of the project cash flow, on payment of the development capital.
The $5.9bn Tampakan mining project is the single largest foreign direct investment in Philippines. The project was granted environmental compliance certificate by the government in February 2013.
In July 2010, the South Cotabato province had, however, banned open pit mining in the Tampakan region, which continues to cause regulatory delays for the project.
The project completion is expected to be delayed by about three years. The project construction is anticipated to start in 2015 with the start of production expected by 2019.
Tampakan mine reserves
The mine holds 2.94 billionn tonnes of resources (16.5mt copper and 17.9moz gold) graded at an average 0.6% copper, 0.2g/t gold and 70ppm molybdenum. This includes 780Mt of measured resources graded at 0.71% copper, 0.28g/t gold and 81ppm molybdenum and 890Mt of indicated resources graded at 0.55% copper, 0.19g/t gold and 69ppm molybdenum. Inferred resources have been estimated at 700Mt graded at 0.5% copper, 0.2g/t gold and 60ppm molybdenum.
The high-sulphidation epithermal deposit overlies a porphyry copper system. The deposit lies at the southern end of the Central Mindanao Cordillera within the Cotabato Fault Zone. The west-north-west trending sinistral strike-slip fault extends 100km and separates the southern and northern structural domain of Mindanao. Two flat lying areas, the Cotabato basin and the Sarangani basin border the Tampakan district to the west and the east respectively.
The core of the district is characterised by a Miocene aged basement sequence consisting of basalt and basaltic andesite lavas and related volcaniclastic sediments. The sequence folds along a north-west striking ramp anticline.
Towards the north, the exposed section of the sequence is defined by the Alip River fault zone, a significant west-north-west trending left lateral structure.
Towards the south, the Tampakan Andesite sequence, the main primary stratigraphic unit within the district, overlies the section.
The Pliocene aged Tampakan Andesite sequence is a stratovolcanic complex composed of andesites. Characterised by deep dissections and erosions, the andesite sequence includes a series of grey to dark green porphyitic flow units composed of pyroxene, hornblende and andesite. It achieves a thickness of more than 650m and plunges 10° to 20° to the west-south-west in the immediate deposit zone. A series of hornblende diorite porphyry stocks and dykes of the same era intrude the Tampakan Andesite sequence.
The Tampakan copper-gold deposit is hosted immediately below the western end of the truncated upper surface of the fourth andesitic volcanic cycle recognised within the complex. The fourth andesitic volcanic cycle manifests within digital elevation models as a Pliocene aged, dissected, central vent stratocone. Widespread-argillic, advanced-argillic and intermediate-argillic alteration affects the sequence till an area of more than 90km².
Mineralisation at Tampakan includes high-sulphidation style copper-gold that is related with, and central to, flat-dipping tabular structures of pervasive silica-clay and silica alteration. At about 0.3% copper distribution at contour, the deposit hosts up to 400m thick flat-lying to gently plunging tabular structures of mineralisation.
The high-sulphidation epithermal mineralisation occurs as veins, fractures, vug-fills or as disseminations at deeper levels. It includes copper-rich digenite, bornite, and enargite. Chalcocite and covellite are also found to a lesser degree. Pyrite is usually found throughout the deposit while enargite is distributed along with late-stage bodies and in zones of strong silicification.
At depths, porphyry-copper style mineralisation includes disseminated chalcopyrite, pyrite and bornite related with quartz-stockwork veining developed variably.
The project is on the island of Masbate, about 350km south of the Philippines capital, Manila.
Mining at Tampakan will be carried out using any of the four options under evaluation in a scoping study. The first option includes block cave mining. A block cave mine with a small open pit is being considered as the second option. The third option includes a block cave mine with a moderately sized open pit while the fourth option focuses on a large open pit.
The second and fourth options also include blending of ore feed that will be processed to produce one copper flotation concentrate. In the third option, ore feed will be processed independently and two copper concentrates will be blended to produce a saleable product. Mining will be carried out to achieve an annual throughput between 10Mtpa and 20Mtpa.
The life of mine is estimated to be 17 years.