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In-Depth
Lucky Find in Yakutia
ALROSA opens its biggest underground mine.
By Anastasia Serdyukova
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Above: Udachny’s open pit mine is the deepest in the world.
All photos courtesy ALROSA and Udachny mine. |
Russia’s diamond miner ALROSA has launched Udachny, its largest underground mine. By 2019, Udachny is expected to reach its projected capacity of four million tons of ore a year, with the reserves expected to last for 60 years.
Udachny, a mine and a town with the same name, is a tiny spot in the endless forested terrain of Yakutia. Located approximately nine miles from the Arctic Polar Circle, the town gets three months of daylight in summer and five months of perennial night. The forests surrounding the city consist of thin fir trees that range in height from 6 1/2 feet to less than 10 feet. Their height is limited by the fact that there is so little sun and the spells of warm weather are so short. Temperatures in the area fall to minus 58 degrees Fahrenheit on average in winter, while 68 degrees Fahrenheit is hot for the summer.
The town was built next to the open pit mine, which was discovered in 1955 and began operations in 1971. Over the years, more than 350 million carats with a value of $80 billion have been extracted from Udachny. During 1980 to 1990, the mine was the flagship of Russia’s rough diamond production, providing approximately 80 percent of the country’s total output in some years. With its depth of 2,100 feet, Udachny is the deepest open pit diamond mine in the world. The mine’s entrance is .9 mile to 1.2 miles wide. Its grayish walls are almost vertical in some places, thanks to the firmness and stability of the soil. At the bottom of the mine, dark blue areas indicate kimberlite that has yet to be extracted. Open pit operations are to stop at the site — and underground mining take over — by the end of 2014.
An estimated 108.6 million carats are lying beneath the open pit, making Udachny the third-largest diamond deposit in the world after Angola’s Catoca, with 142.6 million carats, and Australia’s Argyle, with 117.9 million. The company estimates it will mine 6 million carats a year. Udachny’s underground deposits are estimated to contain 1.31 carats of diamonds per ton of ore. “The mine’s deposits are 159 million tons of ore,” says Alexander Makhrachev, the director of the Udachny mining and processing complex, which is sufficient, he notes, “to keep us busy for the next 60 years with the current level of technology.”
ALROSA has been implementing its plan for underground mine development for more than 20 years. The fact that diamond resources around the globe are declining and prices for rough are rising offsets the costs of underground construction, which at Udachny are estimated at $1.4 billion from initial preparatory work to full capacity.
The company’s first underground mine was International, with 500,000 tons of ore a year; then came Aikhal, with the same production volume. Mir has yet to reach its projected capacity of 1 million tons of ore a year. Currently, approximately 25 percent of ALROSA’s rough comes from its underground mines, but when all the company’s underground mines reach their full production capacity, they will represent 35 percent of total company output.
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Udachny translates as “lucky” and finding such a rich deposit was indeed fortunate for Soviet geologists in 1955. When it came to the construction of the underground mine, the company got some additional good news. “We are lucky to have hard ground here,” says Makhrachev. Hard rock makes underground structures more stable. Another bit of luck came when the company started studying the possibilities of underground construction. Udachny lies in an area of perpetually frozen soil and frozen ore is impossible to work with. “We first dug about 328 feet underneath the open mine to see if the ore would freeze, then we dug another 328 feet. When we saw that the ore was not affected by the cold, we understood that the mine could be built,” says Makhrachev.
The ground consists predominantly of dolomite, which makes the corridors of the underground mine very light-colored. At the moment, two vertical corridors, which are drilled from the mine entrance down to the level of mining operations and which contain lifts, allow miners access down almost 2,300 feet. Then special buses take workers almost nine-tenths of a mile along horizontal tunnels to the site of the kimberlite pipe. The deposit consists of two parts — Eastern and Western bodies of kimberlites, with the latter body twice as rich in resources. There are three parallel tunnels at the moment, each around 328 feet below the other.
Underground mining will be done with sublevel caving. “At the moment, we are engaged in preparatory work, creating a circle corridor around the kimberlite body,” says Igor Fomenko, the head of the underground mine. “The holes are drilled in the rock wall, then the rock is crushed with explosives.” After the body is separated from the rock by a corridor that surrounds it, the ore is taken to a special well almost 30 feet in diameter and raised to the surface for delivery to the processing factory. When one body is worked out, the rock that is on top collapses downward, covering the cavity, and the mining team moves to the next level down. This method is more cost effective compared to the more traditional method for Russian mines where the cavity is covered with concrete. “We would have to use 680,000 tons of concrete to reinforce the walls in the mine, which is double the volume we use at the moment,” says Makhrachev.
The floor of the mine is covered with pools of water, which are ankle deep in some places. Water is also dripping from the ceiling. The volume of water is not much, so there’s no concern of flooding as there is with the Mir underground mine, where the inflow of water is almost six times greater, according to Makhrachev. Yet, there is a large concentration of salt in the water at Udachny. After 30 minutes in the mine, the taste of salt is felt on the lips. “The water contains almost all elements of the Russian chemist Dmitri Mendeleev’s periodic table of elements,” says Fomenko. The concentration is not dangerous for people, but it does corrode the metal of the mining machines so the water is being pumped out to natural underground cavities. “Our geologists are working to find new suitable cavities for the water,” says Makhrachev. “All the cavities should be located below the level of local riverbeds, so the salty water doesn’t get into the ecosystem.”
The other problem at Udachny is to maintain tight control of methane, an explosive gas commonly present in coal mines. Fomenko says that methane sensors are located everywhere in the mine and a massive ventilation system has been installed in the mine. In addition, water tubes run throughout the mine in case of a fire.
Currently, the mine is operating around the clock, with three brigades working seven-hour shifts. During the one-hour break between shifts, the explosive work is conducted. Eight massive heating systems are used to keep the internal mine temperature constant at approximately 39 degrees Fahrenheit, no matter what outside temperatures are.
The ore from the mine is delivered to the Udachny processing factory, where the first diamonds were extracted from the ore in 1976. The plant has a capacity to handle 11 million tons of ore a year. The ore is broken into smaller pieces by large grids, whose production capacity is 1,000 tons of ore an hour. Then the ore goes through smaller grids and additional processing, with 96.7 percent of diamonds extracted from the ore. As much as 67 percent of Udachny rough diamonds are of jewelry quality. Most stones are white, although yellow gems are also being found. Makhrachev says that the majority of the stones are octahedrons and rhombic dodecahedrons, which are good shapes for polishing. The largest diamond from this factory so far has been 320.65 carats. It was extracted in 1989 and is the second-largest stone ever found in Yakutia.
For Nina Zhuravskaya, who is currently in charge of the final cleaning of the stones, it is the clarity and desired shape of the Udachny stones that make them so beautiful. Millions of dollars worth of rough diamonds may pass through her hands daily. “The size of the stones is not the most interesting; sometimes we have stones as small as 20 carats that are magnificent in their form and color,” she says. “For me, it’s just a job like any other.” Zhuravskaya has been working at the factory for 28 years, with five generations of her family living in the town. Despite harsh weather conditions and the remote location several hours by plane away from the nearest big city, she says this is the best place to live. Families say they enjoy hunting and fishing in the area, along with its good ecology and practically zero crime rate.
All 13,000 residents of Udachny are directly or indirectly involved in the mining work. The city consists of 33 five-story apartment buildings, all colored in the brightest shades of yellow, blue and pink, perhaps to compensate a bit for the overall lack of sunshine. Yet, for three months in summer, the nights are as bright as the days. Makhrachev says that there is no crime in town because everyone knows each other. Many specialists come to work at the mine and factory from other parts of Russia because the salaries at Udachny are way above average for the country. As production increases at the site, the company will be recruiting more specialists.
Three more diamond deposits are located close to Udachny. Zarnitsa, the first diamond deposit discovered in Russia, lies approximately 12 miles away. The company is currently evaluating whether mining diamonds at that site is profitable, given the current diamond pricing structure. If the Zarnitsa site is developed, it would add another million carats a year to ALROSA’s output. Prospecting work also is underway at Verhne-Munskoe and Dalnaya pipes that are located nearby. Makhrachev believes that the deposits at those two pipes are substantial enough to keep future generations busy mining diamonds.
Udachny will play a key role in ALROSA’s plans to increase its output to 40 million carats a year in 2020. Fyodor Andreev, the president of the company, said the launch of Udachny would ensure stable rough output that ALROSA can provide for the global mining market. And with diamond deposits dwindling around the world, the value of the underground giant is expected to grow.Article from the Rapaport Magazine - August 2014. To subscribe click here.
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