The Red Dog Mine is a zinc and lead mine in northern Alaska, located about 80 miles north of Kotzebue in the Northwest Arctic Borough. This metal sulfide mine is the second-largest producer of zinc in the world, and is a major source of revenue for native corporations across the state. The main pit is almost out of ore, but in 2010 the mine began extracting ore from an adjacent pit, expected to last until 2031. The mine has had problems with wind-blown ore dust, and wastewater discharge issues have resulted in fines and a large lawsuit brought by the downstream community of Kivalina. Active water treatment and tailings repository maintenance will be needed forever -- to prevent heavy metals and acid discharge into downstream waters.
History and Geology
Metal deposits in the area around Red Dog Mine were first documented by USGS geologists in the 1950’s. These deposits are interpreted as precipitates from an ocean floor hydrothermal vent. These ocean sediments were then buried, metamorphosed, and finally uplifted by the same event that created the Brooks Range. Erosion of the Brooks Range exposed the resulting rock, which contains the worlds’ largest known zinc deposits, along with some lead and silver. Interest in mining these deposits was expressed by both the NANA Regional Corporation Inc. who owns the land, and by a mining company that later became the Teck mining corporation. In 1982 these corporations signed an agreement to develop the mine. In 1986 the State of Alaska agreed to construct a shallow-water port on the Chukchi Sea and a road connecting the port to the mine site. Construction on the port, road, and mine itself began in 1987 and the mine became operational in 1989. A large investment during 2009 led to a record amount of production that year, but the main deposit is expected to be depleted in the near future. The ore from Red Dog is shipped primarily to Asia where it is smelted and refined.
Mining Techniques and Waste Disposal
The Red Dog Mine is an open pit mine which is expected to ultimately reach 1600 m x 915 m x 122 m deep – more than 150 times the volume of the Empire State Building. Though this is a large operation, the ore at Red Dog is so rich that it is significantly smaller than other large mines that produce a similar amount of finished metal. The mine uses conventional mining techniques to extract an average of 9,800 tons of ore per day; first drilling and blasting the rock followed by grinding to a manageable size. The ore is pre-washed and then subjected to froth flotation which separates first the lead and then the zinc. This flotation process uses 200 tons of cyanide per year to increase the separation of the desired components. The resulting ore concentrates are dried using vacuum filters and then sent by road to the port where they are stockpiled until the 3-month shipping season in summer. The port doesn’t allow access to large ships so the ore is then ferried out by barges.
…Acid mine drainage is a major problem with many hardrock mines, including almost all mines where the metal ore is bound up with sulfur (metal sulfide mines)…
…In particular, 90% of the studied mines that originally predicted “low acid mine” drainage potential had acid mine drainage problems at the time of the study…
…an additional problem can also be created when the acid reacts with rock that neutralizes it…
A critical facet of any metal sulfide mine is management of acid mine drainage. When sulfide-rich rock is exposed to the air, it can weather to form sulfuric acid. To prevent this at Red Dog, mine tailings are impounded with some of the waste rock underwater behind a large dam. However, most of the waste rock is stored in stockpiles on the surface, where acid is also generated. The acidic runoff from these piles is directed into the tailings pond, and then all water leaving the tailings pond is treated.
Since these sequestered tailings will leach acid whenever they are exposed, the impoundment will need to be maintained forever to protect downstream waters. The mine is expected to produce around 88 million tons of mine tailings if operation continues through 2031.
Power for the mine is produced by a series of diesel generators, totaling over 40 MW in capacity. Waste heat from these generators is used to heat the buildings on site. The mine uses 15.5 million gallons of fuel per year, plus another 1.4 million gallons for transportation and at the port. Some exploration and drilling for a nearby source of natural gas has been conducted but currently the entire mine is powered by shipped-in diesel. In early 2012, Red Dog announced they were terminating the search for nearby gas.
Because the main pit was projected to run out of ore in 2011-2012, Teck began mining of the adjacent Aqqaluk deposit in 2010. The permitting process to develop the Aqqaluk deposit was completed earlier in the year. Because this deposit was not considered in the initial Environmental Impact Statement for the mine, a new supplemental statement was conducted by state and federal authorities.
This Aqqaluk deposit has only 16% zinc, less than the main deposit at 20.5%, but is expected to keep the mine running until around 2031.
Most of the waste from this project will be placed back into the main pit of the original mine. However, the current tailing impoundment facilities will need to be modified for the additional waste, and the existing dams will have to be raised. After the deposit is mined out, the Aqqaluk pit will be filled with water to limit acid mine drainage.
Employment and Revenue Sharing
The mine employs around 475 people full-time and creates several dozen temporary jobs each year for a total payroll of around $50 million. The mine is the sole taxpayer in the Northwest Arctic Borough and in 2007 paid $230 million in state and federal taxes. Red Dog is also an important purchaser of goods and services in the region, and over half of the mine employees are NANA shareholders. The NANA corporation had set a goal of 100% shareholder employment at Red Dog but high turnover and jobs requiring extensive post-secondary education have kept this from becoming a reality.
Under Section 7(i) of the Alaska Native Claims Settlement Act, 70% of “qualified net profits” received by a regional native corporation from timber and mining operations must be divided among other native corporations in the state. This money is distributed to the other regional corporations, which then distribute half of it to the village corporations in their region. In 2008 NANA paid $122 million of Red Dog royalties to the other Native corporations. As a result, profits from Red Dog are a significant revenue source for native corporations across the state - forming the largest single contribution of income to many village corporations that are nowhere near the mine.
The mine has had a number of problems with wind-blown ore dust, and with wastewater discharge issues. Active water treatment and tailings repository maintenance will be needed forever to prevent heavy metals and sulfuric acid discharge into downstream waters. In addition, there have been accusations that the road between the mine and the port is disrupting animal migrations and affecting subsistence living in the area. Lastly the existence of the Red Dog Mine infrastructure may be used as justification for additional mining projects in the area, such as the nearby Lik Deposit.