Argyle diamond mine
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The Argyle Diamond Mine (English: Arglye diamond mine or Arglye Mine ) is located in Western Australia in the eastern Kimberley region in a remote area. It is about 2,000 kilometers from Perth
This mine promotes worldwide the largest volume of diamonds, it is about one-fifth of world production. Were supported in this mine, according to Rio Tinto 670 million carats, with whom Rio Tinto revenue of U.S. could achieve $ 6 bln.
In Australia, although there are other areas where diamonds were found, but there are only two other diamond mines, the Ellendale Diamond Mine, which is in operation, and the Bow River Diamond Mine, which was operated from 1998 to 2005.
- 3.1 Characteristics of the diamond
- 3.2 diamonds offer
- 3.3 deposits
- 3.4 economy
- 3.5 Underground Mining
Diamonds
As in the Argyle diamond mine only a small amount of diamonds are promoted that are suitable for gemstone production, the mine is not the biggest in terms of its value. It is the diamond mine, which promotes 90 % of pink diamonds in the world. Large amounts of colored diamonds Furthermore, occur naturally in shades of champagne, cognac and the rare blue. The colors denote Champagane and cognac light brown diamonds. The diamond mine, which has been operated in the open pit is currently being switched to an underground mining, which is to begin in 2013.
The Argyle Diamond Mine is also known that it is the first diamond mine of a lamproite volcano chimney, which is operated economically, which is unusual. Because most diamonds are found in kimberlite pipes. Diamond mining, which took place earlier in Lamproitvorkommen, as in the Crater of Diamonds State Park in Arkansas, USA, was uneconomical.
The Argyle mine was up in 2000 in a joint venture of Rio Tinto ( 56.8 %), Ashton Mining Ltd.. ( 38.2 %) and Western Australian Diamond Trust ( 5%). The Argyle diamond mine is now wholly owned by the Rio Tinto Group, a mining company, which also operates the Diavik diamond mine in Canada and the Murowa Diamond Mine in Zimbabwe. Rio Tinto is the third largest producer of rough diamonds with a share of 20 % of world production.
Description
The mine covers an area of 450 km ², which is nearly linear with a length of 1600 meters and a width of 150 by 600 meters. The mine achieved through surface at about 600 meters, its lowest point; this decomposition form is not continued in 2010.
An underground mining is being prepared, and it is intended to continue the diamond production by the year 2018, according to recent statement from Rio Tinto until 2019.
Location
The Argyle mine is located in the Kimberley region in the far north east of Western Australia, south-west of Lake Argyle in the Matsu Ranges. The mine is located approximately 550 km south-west of Darwin and about 185 km from the nearest settlement Kununurra. Most of the 520 workers come from Perth, which is located more than 2000 km, and work in the exchange of two weeks in the mine. In the early years they were flown by air to the mine. In the mine, local residents are employed and a large number of Aboriginal people. The Argyle mine employs 25% of Aboriginal people in full-time and 50 % live there.
About 20 kilometers away there was the Ellendale Diamond Mine, which was operated on a Schwemmlandgebiet of 1998 at the southern end of Lake Argyle to 2005.
Geology
The mine is the first commercially operated diamond mine, which does not promote diamonds in a kimberlite vent. Diamonds also are in alluvial soils. The chimney has been named as " AK -1", even though it is commonly called in Australia Argyle pipe.
Inside the Vukanschlots is olivine lamproitisches rock, mainly tuff and solidified lava. The lying around volcanic facies suggests a lamproitische eruption that created a maar. At the boundaries of the volcano chimney lamproite volcanic breccia with interspersed as smashed rock fragments mixed in by the explosion and was crushed. Minerals of the border facies are zeolite, mica, kaolinite and clay, which are typical signs of hydrothermal mixing after a volcanic eruption.
Diamonds were found in the intact edge of the volcano chimney, as well as in some marginal breccia and Maarfazies. However, some diamonds were cooled during the post-volcanic eruption in the chimney and transformed to graphite.
The volcanic vent was formed by an explosive eruption of magma lamproitischer in a weakness zone of the continental crust.
The diamonds that were found in the Argyle - vent, have an age of 1.58 billion years ago, during the volcano that created the crater and was active between 1.1 to 1.2 billion years ago. These data indicate a relatively short period of about 400 million years ago, in which the diamond formation arose, the diamonds created in a small average size and with unusual physical character of Argyle diamonds. The diamonds that are found in the Argyle - vent, are predominantly eklogitisch. This means that the carbon from which they originated, organic origin.
In connection with the chimney, there were numerous volcanic emanations, the eroded parts of the chimney and alluvial soils created, were incorporated into the diamond. In these soils, they were also actively mined.
Production
The mine holds on earth the top position in terms of the volume of mined diamonds per year with an average of 35 million carats ( 7000 kg ), which is about one third of global production of natural diamonds. The peak value was 42 million carats mined achieved 1994 ( 8400 kg ). Of these, only 5% of amounts recovered are suitable for jewelery making, the rest is " close to a jewelry quality ", or they are suitable for industrial purposes. This value is slightly lower than the normal average of about 20%. (The author Janine Roberts notes that the review " near gem quality " is subjective and misleading because these diamonds can be cut into jewelry, if so decided. ) Since start of mining in 1983, the diamond mine about 750 million carats (150,000 kg) promoted rough diamonds.
Most diamonds of the Argyle mine are brown and they are usually difficult to sell, even though Rio Tinto had some success with a long marketing campaign for their brown and champagnefarbenen diamonds. In contrast, there are no problems with the sale of diamonds in pink, purple and red colors, which are very rare and in high demand and can be achieved for the top prizes. The pink diamonds are of a special team that is based in Perth, processed, polished and sold to customers worldwide.
The mine works with stone and diamond sorting facilities in the mining area. First, the diamonds are removed from the rock and acid washed, sorted and shipped to Perth, where further sorting and sold. Part of the diamond is cut in India, where it allows the low labor costs to cut small diamonds at a profit. This is for the Argyle mine of great importance, as it promotes an average of more smaller diamonds than the other diamond mines.
Characteristics of diamonds
The diamonds of the Argyle mine are on average of lower quality. Only 5% of the diamonds mined achieve a jewelry quality; by world standards is 20 %, the remaining 95 % will be distributed in almost gem quality and industrial diamonds. 80 % of Argyle diamonds are brown, 16 % yellow, 2% white, 2 % gray, 1% pink and green. Although the Argyle mine is the only constant occurrence for red diamonds, but produced only 90% to 95 % of all pink and red colored diamonds. Most Argyle diamonds are classified as type 1, and have a low content of impurities with nitrogen, the colors resulting from a defect in the crystal structure. Argyle diamonds tend in fluorescence under ultraviolet light to blue or dull green, and blue - white under X-rays. The most common inclusions in the diamonds are made of graphite, followed by crystalline inclusions of orange garnet, pyroxene and olivine.
Diamonds offer
Since 1985, every year a small collection sold by pink diamonds; this property is called the Argyle Pink Diamond Tender. On -funded one million carats (200 kg) of rough diamonds, only one carat ( 0.2 grams) Fuchsia polished diamonds is for sale.
In March 2009 Argyle first offered to the rare blue diamonds. The so-called collection "Once in a Blue Moon" was launched in different years later and included blue and violet diamonds in a volume of 287 carats ( 57 g).
Deposit
Initially proven rock reserves the Argyle mine was 61 million tons (t), with 6.8 carats ( 1.36 g ) per tonne, about 400 million carats ( 80,000 kg ). More estimated reserves of 14 million tonnes containing 6.1 carats ( 1.22 g ) per tonne (85 million carats 17,000 kg). 2001 amounted to the reserves of the open pit mine 220 million tonnes with 2.5 to 3.0 carats ( 0.5 to 0.6 g ) per ton of rock, enough for a production by the year 2007. The content of the diamond mine is unusually high, because the most commercially operated diamond mines have only an average content of 0.3 to 1.0 carats ( 0.06 to 0.2 g) per tonne. The diamond deposits in the alluvial soils is now considered depleted.
In 1995, a 300 meter deep test hole on the sole of the mine was carried out as a result of a volume of an estimated 100 million tonnes at a grade of 3.7 carats per ton (0.74 g ) produced. In the mid-1990s, the Western Wall was part of the open mine, which contained 25 million tons of useless rock and threatened to collapse. In 1998 it was decided to remove the unstable part or cut to open up another diamond- bearing rocks in the southern part of the open pit mine.
The exploration costs to review the economic promotion of diamonds below the open pit mine in the volcanic vent were set at AUD 70 million. The reduction is to be completed in the block caving method, a similar procedure as it has been carried out in open pit mining. In late 2005, the Rio Tinto Ltd. Decided that the aspired degradation can be economically carried out in underground and began with the first preparatory actions before the middle of 2006.
Economy
The economic opportunities of the Argyle mine are in their large reserves and the high proportion of below-average diamond. The estimated value of Argyle diamonds is only U.S. $ 7 per carat ( U.S. $ 35 / g); while the value of the Diavik Diamond Mine at U.S. $ 70 per carat ( U.S. $ 350 / g) and the Ekati Diamond Mine at U.S. $ 170 per carat ( U.S. $ 850 / g) is, both in Canada. However, the Argyle mine has comparatively a two or four times as high degree of concentration of diamonds. This makes the extraction of commercial interest, because the mining costs are related to the mass of degraded rock and not to mined diamonds.
Underground Mining
2005 Rio Tinto announced the contract for the development of a future expansion project, to continue the mining underground. The project has been postponed until September 2010, when Rio Tinto announced a new plan for an underground mining, which provided an annual grant of 9 million tons of rock.
The project envisages an underground construction, which places high demands on the design and engineering work to be created. The underground mine is to promote and 2018 diamonds and use the latest technology, including an automated mining technology company Sandvik. The degradation is, however, begin only in 2013, two years later than planned, after the diamond prices had plummeted.
Underground mining requires considerable technical effort, such as ventilation and drainage of the subsoil and protection against invading waters in rainfall under the local climatic conditions, and also static precautions.
History
Small quantities of diamonds that are embedded in Schwemmlandgebieten were known in Australia since the 19th century, the first were found by prospectors who searched for gold. However, no diamond deposits were known in volcanic vents. A systematic search for this source began in 1969 in Western Australia. The Tanganyika Holdings had the Maureen Muggeridge instructed and formed with it the Ashton joint venture after 1976 minerals were found, which indicated a presence of diamonds. In 1979, Muggeridge diamonds in a sample from a floodplain beside a small stream that flowed into Lake Argyle. Soon after the source of diamonds was found in the upper Smoke Creek. On 2 October 1979, the Argyle vent was discovered.
In the following three years the incidence was investigated in terms of economic feasibility and made the decision in 1993 to break down. The diamond mining in alluvial started immediately, while the open pit has been built up over a period of 18 months at a cost of AUD 450 million and began in December 1985.