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Red Dog Mine

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Red Dog Mine is the largest zinc deposit mine in the world. Located in Kotzebue, in northwest Alaska, the zinc concentrate currently accounts for 10 percent of the world’s supply.[1] An open-pit mine, Red Dog is mined by conventional drill-and-blast methods. Aside from zinc, it also produces lead concentrate.

Red Dog Mine is leased to Teck Cominco Alaska Inc. by agreement with the Northwest Alaskan Native Association (NANA) Regional Corp. Inc., a native Alaskan development corporation.[2] Teck Cominco owns and operates the facilities that produce and distribute the minerals mined from Red Dog Mine but the property is owned by NANA.

In 2005, Red Dog was mined for 3.1 metric tons of ore, with a grading of 21.7 percent zinc, 5.6 percent lead, and an output of 568,000 tons of zinc and 102,300 tons of lead. Teck Cominco made a profit of US$317 million (CA$325 million). Although it pales in comparison to the lead and zinc deposits that were produced, 1.95 million ounces (55.3 million g) of silver in lead concentrates were also produced.[3]

The mine consists of four separate ore bodies and has been in operation since 1989. It is expected that the main ore body will expire in 2012.

Contents

[edit] Construction History

[edit] Early Beginnings

Red Dog Mine first attracted attention from geologists in the 1950s. In the 1980s, several major mining companies expressed interest in the land that was awarded to NANA. Cominco American signed an agreement to mine the land for ore. Cominco American eventually changed its name to what it is today—Teck Cominco. The first mining operations were performed at Red Dog in 1989 and continue today.

[edit] The Four Ore Bodies

The mine at Red Dog contains four distinct deposits: Main, Aqqaluk, Paalaaq and Qanaiyaaq. All comprise siliceous shale and chert.

The Main pit has produced 19.5 million metric tons of ore since 1989, 20.5 percent of which has been zinc. While this pit is currently being mined, it will be completed by 2012, after having reached a size of 5,200 feet by 3,002 feet by 400 feet (1,585 m x 915 m x 122 m).

Aqqaluk ore body consists of 55.7 million metric tons, 16 percent of which is zinc. Aqqaluk is positioned along the side of the Main pit and is currently in production. The waste rock extracted and stripped from this body will be placed in the Main pit upon its completion.

Both the Quanivaq and Paalaaq ore bodies have zinc deposits that are located underground and will have to be accessed via a series of tunnels and mine shafts, provided NANA allows Teck Cominic to mine them. Qanaivaq ore body has 4.7 million metric tons, of which 23.7 percent is zinc. This is an open-pit mine that is currently undergoing studies. Paalaaq ore body has 13 million metric tons with 15 percent zinc and is currently inactive.

[edit] Mining Processes

The conventional truck-and-shovel method has proven the most suitable mining method to employ in the arctic conditions. Low mining rates of 10,000 tons per day were the result of high grades, low stripping ratios (0.8:1), and short distances in which the materials had to be transported.

The pit consists of a variety of slopes in several sections, calling for blasthole drilling with Ingersoll Rand and Drilltech rotary and in-the-hole drills. The drills vary from 3.5 to 6.5 inches (9 to 16.5 cm) in diameter for these purposes. Dry areas in the open pit call for the use of an explosive known as ANFO. In the areas that were met with wetter conditions, packed slurry was used.

Caterpillar equipment dominated the majority of the processes involved in this pit. Three 13-cubic yard (9.9 m3) loaders, five haul trucks with a 77-ton capacity, four dozers, two utility wheel loaders, two road graders, and a water/sand truck were employed to carry out the mining operations.

[edit] Modern Technology

The Red Dog Mine is a complex mine that requires a number of modern techniques. These include modular construction, tower mills, column cells, and pressure filters. The exit of the pit is worked on by a series of crushers. The primary gyratory crusher is responsible for crushing the materials to -5.9 inches (-150 mm) in the initial phase, but because further crushing is necessary, materials are often crushed smaller by a secondary backup jaw crusher.

Once the materials are crushed, they undergo a grinding sequence involving Fuller SAG and ball mills to reduce the ore to 80 percent for primary flotation. The ore is grinded a second time by tower mills, resulting in an 80 percent reduction. When the grinding is complete, treated water is used to reduce presence of metal ions in the ore, as they affect its flotation ability.

Flotation occurs inside Maxwell cells outfitted with Outokumpu mechanisms and in CESL column cells, which are provided by Canadian Process Technologies. Once the flotation circuit is controlled, zinc and lead concentrates are produced.

Ore production was improved further with technology that was completed in late 2001. A $90 million project taking 18 months to build was completed and became known as the optimization program. It involved installing a zinc concentrate thickener and new 65.4-cubic yard (-50m3) Outokumpu flotation cells. The capacity of the plant was subsequently increased to 1.1 metric ton per year of zinc concentrates.

[edit] Transportation and Facilities

Once the ore bodies are mined, they are transported by specially designed Arrow Transportation trucks as far as 52 miles (83 km) to port facilities in Chukchi Sea. The trucks were chosen for their hauling capacity of 85 tons per load, carried in two side-dump trailers at a rate of up to 50 loads per day, year-round. Once received at the port facility, the ore is stored in one of two 850,000-ton capacity storage buildings. The ore is shipped in the span of 100 days, in consideration of arctic climate. Two barges ship the lighter concentrate to vessels offshore and a barge-based Caterpillar 988 loader unloads the concentrates for shipment. The shipment is divided between two destinations: Cominco’s smelter in Trail, British Columbia, and between customers located in Europe and the Far East in July and October. The specified dates are the best times to transport materials from the harsh weather conditions experienced in the arctic region.[4]

[edit] Over the Years

In 2002, Red Dog Mine experienced a tremendous financial loss, costing Teck Cominco $28 million. The loss was the result of the deteriorating financial value of lead and zinc, which sold for 20 cents and 35 cents per pound (0.45 kg), respectively. The price has since risen steadily, to an average of $1.66 per pound (0.45 kg) for zinc and 99 cents per pound (0.45 kg) for lead in 2007.

Teck Cominco is currently under an agreement resulting in NANA receiving a 25 percent share of the profits accrued from the mine. It is said that the percentage will rise by five percent after the first five years, up to a maximum of 50 percent.

[edit] Equipment Used

[edit] Refurbishment/Recent Projects/Renovations

By the end of 2005, the mine had produced 72.2 metric tons grading 17.7 percent zinc and 4.7 percent lead. The mine had 37.9 metric tons of measured mineral resources, which Teck Cominco continues to drill. The specific regions targeted by Teck Cominco are the Anarraaq, Aktigiruk, Paalaaq, and Su Lik deposits.[5]

[edit] Unique Facts

  • The Red Dog Mine is a member of a small group of American metal production mines to receive an ISO 1400:2004 certification. The certification is the result of the mine operating via systems that support and protect the environment.
  • The Red Dog Mine has contributed $540 million the Alaskan economy, as well as to Alaska’s native population.
  • The mineral zinc can be applied to low-emission technologies, making it a valuable resource in reducing the carbon footprint.
  • The zinc at Red Dog makes up 80 percent of the zinc ore that is mined and processed in the U.S., totaling to 725,000 metric tons. Half of this amount is used for galvanizing purposes (to coat iron or steel and prevent rust). Twenty-one percent is used as an alloy; 16 percent to create brass and bronze; and the remaining eight percent is for miscellaneous uses such as chemicals, paint, and rubber.
  • Of all the lead mined in the U.S., 30 percent derives from Red Dog Mine.[6]
  • Prior to the discovery of minerals at Red Dog, the creek adjoining the mine consisted of deposit that was toxic enough to kill off a plantation. The creek now provides drinking water that meets EPA standards.
  • The name Red Dog derives from the name Red Dog Creek, named as such for the dog of pilot Bob Baker, who frequented the area.

[edit] References

  1. Leach, Dr. David. The Giant Red Dog Massive Sulfide Deposit Brooks Range, Alaska: Discovery, geology, geochemistry and genesis. CPGG.com, 2008-09-25.
  2. Red Dog Mine. TeckCominco, 2008-09-25.
  3. Red Dog Lead, Zinc and Silver Mine, AK, USA. Mining-Technology.com, 2008-09-25.
  4. Red Dog Lead, Zinc and Silver Mine, AK, USA. Mining-Technology.com, 2008-09-25.
  5. Red Dog Lead, Zinc and Silver Mine, AK, USA. Mining-Technology.com, 2008-09-25.
  6. About Red Dog. RedDogAlaska.com, 2008-09-25