| Summary: | The Aitik mine is a large Cu-Au producer in Europe with an annual production of 28 million tons of ore and a planned expansion of production to 36 million tons of ore until year 2013. Large ongoing investments are done in the mine and a new processing plant is built to manage the capacity increase. The mine is situated 15 kilometers from the town Gällivare, in northern Norrbotten, Sweden. The ore is a large porphyry type deposit with low grades of disseminated copper (0,27 %) and gold (0,16 ppm). Porphyry copper ores usually have low recoveries when flotation is used as an extraction method and also the Aitik mine has shown historically low gold recoveries (< 50 %).The Aitik deposit is situated in 1.9 Ga Svecofennian volcanic and sedimentary rocks formed in a volcanic arc environment and later deformed and metamorphosed at amphibolite facies. The main ore zone consists of biotite and muscovite schist and gneisses. A thrust fault divides the main ore zone from the hanging wall that contains feldspar biotite amphibole gneiss. In the footwall the feldspar biotite amphibole gneiss also is found and an intrusion of quartz montzodiorite.In this study, horizontal and vertical zoning patterns were recognized in data based on the block model that consist of drill cores and drill ship samples since the mine started 1968. The vertical zoning shows a decrease in high (> 0,6 % Cu) copper grade areas and an increase in high (>0,3 ppm Au) areas towards the depth. An increase in the amphibole content is seen in the biotite gneiss towards depth. The gold mineralized areas are trending northeasterly and plunging northeast, and for copper north-northwest. The horizontal zoning can be seen in the middle of the ore zone where a high-grade area of disseminated sulfides in potassic altered biotite gneiss/schist exists. Further towards the hanging wall, a low grade, strongly sericite altered and pyrite-rich schist is common.Gold-rich areas are found close to the hanging wall in strongly sericite schist altered rock and in a ...
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