The Red Dog mine is a zinc and lead mine located in a remote region of the Arctic, within the boundaries of the Red Dog Mine census-designated place in the Northwest Arctic Borough of the U.S. state of Alaska.
The mine is the world's largest producer of zinc and has the world's largest zinc reserves. Red Dog accounts for 10% of the world's zinc production. Red Dog accounted for 55% of the mineral value produced in Alaska in 2008. In 2008 the mine produced 515,200 metric tons (507,100 LT; 567,900 ST) of zinc, 122,600 metric tons (120,700 LT; 135,100 ST) of lead, and 283 metric tons (9,100,000 ozt) of silver, for a total metal value of over one billion dollars. At the end of 2008 the mine had reserves of 61,400,000 metric tons (60,400,000 LT; 67,700,000 ST) of zinc at a grade of 17.1% and 61,400,000 tonnes (60,400,000 LT; 67,700,000 ST) of lead at a grade of 4.5%, as well as significant additional zinc and lead in the less well-measured resource category.
Red Dog is located on land owned by the NANA Regional Corporation and is operated by the commercial mining company Teck Resources in partnership with NANA Development Corporation. Ore concentrate taken from the mine is trucked westward to a shipping facility on the Chukchi Sea and stored there until the shipping season.
The mine, which produces from an open pit, is currently mining the Aqqaluk orebody, immediately adjacent to the previous pit, Aqqaluk contains an additional 56 million metric tons (62 million short tons) of lead and zinc ore. The expansion is expected to keep the mine operating until 2031.
History
In the mid-1950s, Bob Baker, a local bush pilot and prospector, noticed red-stained creeks in the area, but was unable to land his plane nearby. In 1968, at Bakers urging, a U.S. Geological Survey geologist sampled rocks and stream sediments in the region, including samples from the future site of the Red Dog mine, and named Red Dog Creek after Bob Baker's dog, an Irish Terrier (Tailleur; USGS Open File 70-319). In the mid 1970s, after investigations by BLM-contracted geologists confirmed significant mineralization, interest in the region from major mining companies and NANA intensified. Significant exploration, soon including drilling, of deposits in the region began in 1975 (Alaska Minerals Yearbook 1978-1979). In 1980 the Alaska National Interest Lands Conservation Act (ANILCA) became law and NANA officially selected the land underlying Red Dog. Drill exploration of the Red Dog deposit began in 1980, by Cominco American. In 1982 NANA and Cominco American (a mining company that had staked the land, and later became Teck Cominco) signed an agreement to develop the deposit. In 1986 the State of Alaska agreed to fund and take ownership of a road (DeLong Mts. Transportation System) from Red Dog to the coast, and a shallow-water port site. Also in 1986, residents of Kotzebue and 10 other area villages voted to form the Northwest Arctic Borough, to be economically based on taxing the Red Dog mine. Construction of the road, port site, and mine began in July 1987. Mine operations commenced in December 1989.
Economics
Under the terms of the Teck Cominco/NANA agreement, NANA received royalties of 4.5% until the capital costs of the mine were recovered, which occurred in late 2007. At this point, the royalty due to NANA increased to 25%, and will increase by an additional 5% every year, to a maximum of 50%. Under the terms of the Alaska Native Claims Settlement Act of 1971 (ANSCA), which created NANA and the other native corporations in Alaska, NANA must share approximately half of its profits from natural resources with the other eleven land-based regional native corporations. If the mine remains profitable at the current level, this will mean a distribution of several hundred million dollars a year of mine profits to the regional native corporations.
Geology
The Red Dog area has the world's largest known zinc deposits: the four at Red Dog as well as Anarraaq and Su-Lik, respectively 10 and 18Â km (6 and 11Â mi) northwest. They are stratiform massive sulfide bodies hosted in Carboniferous black shale and altered carbonates. Mesozoic mountain-building tectonic events (i.e. the Brookian orogen that built the Brooks Range) deformed and thrust faulted the sedimentary strata that host the deposits and the deposits themselves. Subsequent uplift and erosion exposed parts of the deposits at today's earth surface.
Red Dog is an example of a sediment-hosted Zn-Pb-Ag deposit, with the zinc-lead ore considered to have been deposited on the sea floor as a strata of sulfide sediment. Zinc, lead, silver, and barium were deposited in black muds and carbonates on or beneath the seafloor, in a deep quiet ocean basin, some 338 million years ago in the Mississippian period.
Fluids probably percolated through a huge mass (hundreds of square kilometers) of sediments. The nature of the fluids caused them to absorb and concentrate trace amounts of zinc and lead contained in the rocks the fluids were passing through. These metals were then caused to precipitate, by chemical or biological or physical agents, from the fluid onto or into the seafloor to form the Red Dog deposits.
One model holds that very saline brines formed in a restricted ocean basin within a hundred kilometers of the site of the Red Dog deposits. The brine fluid infiltrated the subsurface and was tectonically pumped through the rock mass, becoming enriched in metals as it stripped those metals from the rocks it passed through. The fluid traveled several kilometers below the earth's surface. The fluid eventually reemerged through fault systems focused on the location of the Red Dog deposits, in a manner somewhat similar to the process surrounding black smokers.
Reserves and resources
Ore bodies and contained zinc at Red Dog consist of;
- Main pit ore body with 19.5 million metric tons (21.5 million short tons)of ore containing 20.5% zinc. The figures represent the orebody before mining began in 1989. This is the currently permitted area of active mining, which is expected to be mined out by 2012. The ultimate size of this pit will be 5,200Â ft by 3,000Â ft by 400Â ft (1,600Â m x 900Â m x 120Â m) deep.
- Aqqaluk ore body with 55.7 million metric tons (61.4 million short tons) at 16% zinc. This is adjacent to the Main pit. It is well understood geologically and metallurgically. A Supplemental Environmental Impact Statement is expected to be produced in 2008 as part of the process of permitting the development of this ore body. Most of the waste rock from this operation is expected to be placed in the depleted Main pit.
- Qanaiyaq ore body with 4.7 million metric tons (5.2 million short tons) at 23.7% zinc. Also an open-pit target, studies of the ore characteristics of Qanaiyaq continue.
- The Paalaaq ore body with 13 million metric tons (14.3 million short tons) at 15% zinc and the Anarraaq ore body with 17.2 million metric tons (19.0 million short tons) at 15% zinc are both deep underground and will be accessed by tunnels and shafts, if they are eventually mined.
Geography
Red Dog mine is located at 68°4′19″N 162°52′34″W (68.071989, -162.876044). It is in the DeLong Mountains in the remote western Brooks Range about 90 miles (144 km) north of Kotzebue and 55 miles (88 km) from the Chukchi Sea.
Regional
The mine lies within the Northwest Arctic Borough, the boundaries of which are exactly coincident with the boundaries of the NANA Regional Corporation. The borough, which is approximately the size of Indiana, has only 11 communities and a population of only 7,208 people, 84% of which are native or part native, and 40% of which report speaking native at home. No roads connect the communities. The nearest permanent settlements to the mine, roughly 60 miles (100Â km) west and 50 miles (80Â km) south respectively, are the villages of Kivalina, population 377, and Noatak, population 428, at the 2000 census.
Although native populations have historically used areas around the mine and port for seasonal food-gathering there are no permanent residents at the mine or port site. The workforce consists of about 460 employees and contractors, of which somewhat more than half will be on-site at any given time. All staff work on a rotation, most on either a 4 weeks on/2 weeks off or 2 week on/1 week off schedule. At the mine, everybody stays in the single large housing unit, tucked in among the process buildings near the edge of the open pit. A small portion of the work force stays at the port site. Contracted employees stay at the ConPac south of the main accommodations during the summer months. NANA shareholders comprise 56% of the mine's workforce.
The Red Dog mine provides over a quarter of the borough's wage and salary payroll. While many of the borough's residents benefit from the mine and associated economic activities, virtually all of the borough's residents rely on subsistence activities which are dependent on a healthy environment.
Environmental concerns
Before discovery of the mineral deposits at Red Dog, the creek draining the deposit was too toxic to support life. It now meets drinking-water standards. On June 13, 2007 the State of Alaska removed two creeks (Red Dog Creek and Ikalukrok Creek) near the Red Dog mine in Northwest Alaska from the most-polluted waters list with EPA's approval. The mine discharges treated water into Red Dog Creek, a tributary of Ikalukrok Creek. Pre-mining studies on Red Dog Creek revealed naturally high concentrations of cadmium, lead, zinc, aluminum, and other metals. Before mining began, aquatic life uses were not present in the main stem of Red Dog Creek because of the natural toxic concentrations and low pH. After mining began, year-round release of treated mine wastewater allowed a population of Arctic Grayling to establish themselves in Red Dog Creek. That fish population is now protected by regulations.
Toxic waste
According to the U.S. Environmental Protection Agency (EPA), Red Dog Mine creates more toxic waste than any other operation in the United States. But, almost all (over 99%) of the "toxic waste" reported by Red Dog are rocks (waste rock and tailings) which naturally contain >2% sulfide minerals, thus making them reportable as "toxic waste". All of the waste rock and tailings material remains in permanent disposal on-site, contained, and treated as necessary by the mine operations. The EPA notes about Red Dog's rank, "No conclusions on the potential risks can be made based solely on this information."
Leaching of metals and acids from waste rocks into the environment is a valid concern. The waste rock piles are contained and all runoff water is monitored and treated to water quality standards. Monitoring, and mitigation if necessary, will need to continue throughout the mine life and for many decades after mine closure.
In 2014, state regulators approved a plan which allowed the mine to continue using Red Dog Creek as a mixing zone, although there has been a long-discussed plan to build a 52-mile pipeline to the Chukchi Sea to avoid dumping wastewaster into the creek.
Heavy metals (lead and cadmium) in mosses adjacent to the haul road
A 2001 study for the National Park Service (NPS) reports in its Executive Summary that, "Concentrations of Cd and Pb...exceed medians (and in most cases maxima) from all 28 countries in the Nordic moss monitoring program, including many of the most polluted countries in Central and Eastern Europe and all areas of western Russia." That sentence is often misunderstood as a comparison of levels of pollution at Red Dog to levels of pollution at industrial sites elsewhere. The 2001 NPS study does not compare pollution at Red Dog to pollution at polluted sites in Europe: it does not conclude that the Red Dog area is more polluted than the worst-polluted areas of Central and Eastern Europe or western Russia. There are hundreds of sites in Central and Eastern Europe and western Russia that are incomparably more polluted than the Red Dog area, e.g., Dzerzinsk and Norilsk in Russia, Chernobyl in Ukraine, and Baia Mare in Romania
The statement quoted above compares samples collected in 2001 adjacent to Red Dog industrial activity to samples collected for the Nordic moss monitoring program: samples which are deliberately collected as far from urban and industrial areas as possible. The Nordic moss monitoring program follows a protocol that demands that samples be collected at least 300 meters from a road and that samples be collected in non-urban areas. Significantly, samples for the study at Red Dog included the loose dust on the moss, while the Nordic moss monitoring program moss samples were shaken to remove dust.
The 2001 NPS study also collected and analyzed soil samples at the moss-collection sites: no elevated levels of lead or cadmium were detected. Additional studies conclude that the concentrations of heavy metals detected in water, soil, caribou, fish, and berry samples collected from the Red Dog mine area do not pose a public health hazard. It is generally agreed that years of operation of tarp-top haul trucks (one every 15 minutes) carrying lead-zinc concentrate resulted in lead and cadmium-bearing dust contamination along the edges of the haul road. Fortunately this poor practice has not resulted in a threat to human safety. The entire concentrate-haulage system has been improved, including tight-fitting seals on side-dump trucks and enclosure of conveyor belts at the port site.
Measurable direct effects of the mine on human health
Repeated testing of blood samples from area villagers, and repeated testing of area village water supplies have shown no elevated levels of lead or other heavy metals. Blood tests of mine workers, for lead levels, are done regularly. A few mine workers have experienced elevated lead levels.
Proposed port site expansion
Local inhabitants have expressed concerns that the proposed expansion of docking facilities may detrimentally change the migratory patterns of marine life.
Transportation
A 52-mile (84Â km) long haul road connects the mine to the mine's port site on the Chukchi Sea. The mine and port site are accessible only by air, except during the 100-day shipping season. The mine's airport, known as Red Dog Airport, provides the main access. Mine workers from remote villages in the region are ferried to the mine on small aircraft. Alaska Airlines is contracted by the mine to fly other mine workers out of Anchorage. Until 2007, gravel-strip capable Boeing 737-200 Combi aircraft were used. These ships have a cargo door in the front part of the aircraft and a separate rear passenger cabin. In 2005 the runway was paved, in anticipation of newer Boeing 737-400 Combi aircraft which are not equipped to land on gravel.
See also
- Sedimentary exhalative deposits
- Acid mine drainage
- Land rehabilitation
- Open-pit mining
- Metallurgy
- Zinc mining in the United States
References
External links
- NANA Regional Corporation
- Red Dog Mine