Red Dog – Cominco’s Arctic Experience Pays Off Again

The Red Dog zinc-lead deposit, said to be the world's second largest, is located inside the Arctic Circle in northwestern Alaska - a location too harsh and remote for some mining companies but just right for Cominco Ltd. The complex has been in operation since November 1989 and is producing 508 kt/a (560,000 stpy) of zinc concentrate, 109 kt/a (120,000 stpy) of leadconcentrate and 45 kt/a (50,000 stpy) of an Imperial Smelter Feed, a combined zinc-lead mixture that is too small to separate. All of this concentrate production derives from a relatively modest mine production of 5.4 kt/ad (6000 stpd) extracted from a surface pit. Despite being a high-grade zinc-lead deposit, Red Dog's metallurgy is complex, requiring a very fine grind and use of column cells for flotation. The Red Dog complex is located in the DeLong Mountains. They are characterized by eight stack and folded thrust blocks that contain sedimentary and igneous rocks. The Red Dog deposit is located in the second lowest thrust and ist hosted by late Mississippian to Permian age black shale, the Ikalukrok member of the Kuna formation. The Red Dog mining complex is operated by Cominco Alaska, Inc., a wholly owned subsidiary of Cominco American, Inc, which, in turn, is owned by Cominco Ltd. In 1980, the deposit region was acquired by NANA Corp. as part of the Native American Claims Act Settlement of 1971. NANA is one of 12 such Native Corporations in Alaska. In 1982, NANA and Cominco American signed a develop¬ment agreement and formed Cominco Alaska to manage the project.