The Distribution, Character, and Rhenium Content of Molybdenite in the Aitik Cu-Au-Ag-(Mo) Deposit and Its Southern Extension in the Northern Norrbotten Ore District, Northern Sweden

Christina Wanhainen,David Selby,Wondowossen Nigatu,Roger Nordin,Claire Mcleod,Nils-Johan Bolin

doi:10.3390/min4040788

Christina Wanhainen, David Selby + Show 4 more

Open Access

https://doi.org/10.3390/min4040788

Copy DOI

Abstract

Molybdenite in the Aitik deposit and its southern extension was studied through mineralogical/chemical analysis and laboratory flotation tests. It is demonstrated that molybdenite varies considerably in grain size, ranging from coarse (>20 μm) to very fine (<2 μm) and occurs predominantly as single grains in the groundmass of the rocks, as grain aggregates, and intergrown with chalcopyrite and pyrite. The dominating molybdenite-bearing rocks are the mica schists, the quartz-monzodiorite, and the Salmijarvi biotite-amphibole gneiss, the latter containing mostly medium-coarsegrained molybdenite. Later geological features, such as garnet-magnetite-anhydrite-K feldspar alteration and pegmatite dikes appear to be responsible for a significant part of the distribution pattern of molybdenite. Molybdenite grains contain up to 1587 ppm Re, with an average of 211 ± 10 ppm in Aitik molybdenite and 452 ± 33 ppm in Salmijarvi molybdenite. The higher Re concentrations are found in molybdenite associated with sericite- and quartz-amphibole-magnetite altered rocks, whereas low Re values occur in rocks in which potassic alteration is prominent. Molybdenite recovery is influenced by the mineralogy of the host rock and the alteration grade; hence both of these factors will have an impact on potential recoveries. The recovery of molybdenite was lower from flotation feeds with significant amounts of Mg-bearing clay-micas.

Highlights

The Aitik porphyry Cu-Au-Ag-(Mo) deposit is located 60 km north of the Arctic Circle at latitude67°04'N and longitude 20°57'E in the Gällivare area in northern Sweden (Figure 1)
We describe the character of molybdenite in the Aitik deposit, and demonstrate the application of qualitative and quantitative mineralogical data derived from optical microscope, QEMSCAN (Quantitative evaluation of minerals by scanning electron microscopy) and ICP-MS
QEMSCAN, ICP-MS, and flotation laboratory test studies on molybdenite, the diversity of its character, occurrence, and rhenium content, and its response to the standard copper flotation procedure used for the Aitik ore has been thoroughly characterized

Summary

Introduction

The Aitik porphyry Cu-Au-Ag-(Mo) deposit is located 60 km north of the Arctic Circle at latitude67°04'N and longitude 20°57'E in the Gällivare area in northern Sweden (Figure 1). The Aitik mine is by size the largest open-pit metal mine in Europe and the main pit measures over 3 km in length, 1.1 km in width and 435 m in depth (Figure 2). Production in the Salmijärvi open-pit, which is situated in the southern strike prolongation of the Aitik main pit and planned to be 800 m long, 400 m wide and 275 m deep, started at the end of. The Aitik deposit was discovered in 1932 and has been in production since 1968 when it started as a 2 Mt/year open-pit operation. Ore reserves at the announcement of the Aitik 45 Mt expansion project in May 2014, were 1085 Mt grading 0.22% Cu, 0.14 ppm Au, 1.5 ppm Ag and 26 ppm Mo, with remaining measured and indicated mineral resources totaling

Methods

Results

Discussion

Conclusion