Red Dog Operations, located in northwest Alaska, U.S.A. near Kotzebue, is one of the world's largest zinc mines.
The mine and concentrator properties are leased from, and were developed under the terms of a development and operating agreement with the NANA Regional Corporation, Inc. ("NANA"), a native Alaskan development corporation.
Red Dog Operations is an open-pit truck-and-loader operation, using conventional drill and blast mining methods. Mineral processing facilities use conventional grinding and sulfide flotation methods to produce zinc and lead concentrates.
Concentrates produced at Red Dog are shipped to our metallurgical facilities at Trail, British Columbia and to customers in Asia and Europe. Because of arctic weather conditions, the concentrate is stockpiled at the port facility and is typically shipped to customers between early July and late October.
The Red Dog Main Pit is a conventional blast-load-and-truck open-pit operation with special provisions for operating in the arctic climate. The Main Pit produced 582,500 tonnes zinc and 131,500 tonnes lead in concentrate in 2009 but reserves will be exhausted in 2011.
The mine is located in the DeLong Mountains of Alaska's Brooks Range in the northwest Arctic Borough near Kotzebue. The remote site is approximately 144 kilometres (90 miles) north of Kotzebue and 88 kilometres (55 miles) from the Chukchi Sea.
Temperatures average from -21oF to 15oF during winter; from 40oF to 60oF during summer. Temperature extremes have been recorded from -59oF to 75oF. Snowfall averages 48 inches, with 10 to 13 inches of total precipitation per year.
There is a 55-mile gravel road from the mine to the shallow-water port for staging and exporting zinc and lead ore. The port is ice-free only 100 days a year. The port and road are state-owned. Barges deliver supplies, fuel and equipment each summer. A gravel runway is available for light aircraft.
Red Dog's sulphide ore zones lie in sedimentary exhalative deposits within Mississippian to Permian black shales. They are overlain by barite-rich rock and a 20-30-m-thick cap of oxidized mineralization. Most of the weathered (oxidized) material has already been mined from the Main deposit. There are four separate deposits - Main, Aqqaluk, Paalaaq and Qanaiyaaq.
The fragmented nature of the rocks and high-grade zinc-lead veining is unusual in sedex deposits. Water-soluble zinc and iron sulphates, and abundant bitumen and native sulphur all make for challenges in the plant.
Deposit is located adjacent to and northeast of the original deposit. It has proven and probable reserves of 51.6 million tonnes grading 16.7% zinc and 4.4% lead. The Paalaaq deposit is partially delimited and has an inferred resource of 13 million tonnes grading 15% zinc and 4% lead. The Anarraaq deposit is located 10 km north of the Red Dog mine.
Mining & Operations
Red Dog is an open-pit mine using conventional truck-and-loader methods with special provisions for operating in the arctic climate. Red Dog has a production capacity of over 600,000 tonnes per annum of zinc contained in concentrate. High grades, low stripping ratio (0.8:1) and short haul distances result in the low mining rate of 10,800t/d. Bench heights are 7.6m and pit slopes vary depending on wall material.
Drilling involves Ingersoll-Rand and Drilltech rotary and in-hole drills with diameters of 90 -165mm. ANFO is used in the drier areas of the pit and packaged slurry in the wet areas. A small fleet of mainly Caterpillar equipment consists of three 9.9m³ loaders, five 77t haul trucks, four dozers, two utility loaders, two graders and a water/sand truck.
Red Dog incorporates several new techniques: modular construction, tower mills, column cells and pressure filters. A primary gyratory crusher and backup jaw crusher are sited at the exit from the pit. The ore is crushed to -150mm in the primary crusher. The mill grinding sequence consists of Fuller SAG and ball mills, which reduce the ore to 80% - 65µm for primary flotation. Tower mills regrind to Zn 80% - 22µm and Pb 80% -19µm. Treated water is used in the grinding circuit to minimize metal ions that inhibit flotation performance.
Flotation is carried out in Maxwell cells, retro-fitted with Outokumpu mechanisms, and in CESL column cells. On-stream analyzers, providing real-time assay information, control the flotation circuit. The result is a zinc concentrate at 55.2% Zn, 3% Pb and 137g/t Ag and a lead concentrate at 56.1% Pb, 11.7% Zn and 435g/t Ag. The concentrates are dewatered using pressure filters.
Zinc and lead concentrates are hauled by truck from the mine to the port site, and fuel and freight are hauled on the return. During the 100-day shipping season, two lightering barges and four tugboats lighter the concentrate to ships anchored offshore due to a shallow port.
Environment and Community
Red Dog is a joint venture between Teck Resources Limited and NANA (Native Eskimo people of Northwest Alaska). The joint venture provides NANA with revenue, employment, training, subsistence resource protection and cultural preservation. With NANA as the land owner, Teck Resources Limited financed and developed the project and is responsible for the day-to-day operation and marketing of the concentrate. The mine currently employs 580 people and 52% are NANA shareholders. This is one of the highest indigenous hire percentages in the world.
Red Dog achieved an environmental milestone by receiving ISO 14001 certification for its Environmental Management System (EMS) in 2004. With this accomplishment, Red Dog has joined an elite group of US mines with certified EMS programs. The development and implementation of the EMS was a multi-million-dollar effort that took more than three years and 25,000 hours to complete. Embedded in the system is a mechanism for continuous improvement and impact minimization with a focus on compliance assurance.