Poles apart: GeoProMining outlines its work in one of the coldest places in the Northern Hemisphere

Posted on Mar 4, 2013 in GPM in the media

Poles apart

GeoProMining outlines its work in one of the coldest places in the Northern Hemisphere

Mining Magazine
March 2013

The international diversified mining group GeoProMining (GPM) has two assets in the Sakha Republic (Yakutia), northeastern Russia – the Sarylakh- Surma production complex, which consists of the Sarylakh mine and a processing plant, and Zvezda, which is developing the Sentachan gold and antimony deposit.

The Sarylakh-Surma Complex and Zvezda have been part of GPM since 2007. When purchased by GPM, these facilities were not operational. After substantial investments, GPM re-launched the operations of both companies in 2008, and since then they have been developing steadily.

The output of Sarylakh-Surma and Zvezda is increasing every year. GPM has modernised and re-equipped its mining and production facilities, enhancing procurements and technologies. In 2012, GPM’s assets in Yakutia produced 11,200t of antimony concentrate.

The territory of the Sakha Republic is unique in terms of the variety and volume of mineral resources, not only compared with the rest of Russia but on a global scale. It has deposits of oil, gas, coal, ferrous ores, base and precious metals, rare earth metals, diamonds and other mining and chemical raw materials. Yakutia has also not been thoroughly explored so far, which implies a high potential to discover new mineral deposits.

GPM’s Sarylakh mine is located in the Oymyakon ulus (district) in the vicinity of Oymyakon – the Pole of Cold, or the place where the lowest air temperature has been recorded in the Northern Hemisphere. According to the Russian Geographic Society, the lowest temperature registered in Oymyakon is -67.7°C. The place is also famous for the large variation in temperatures, ranging 108ºC from –67.7°C in winter to +37°C in summer.

The Sentachan mine is located in a district with temperatures ranging from -59°C to +27°C during the year. Cold northeastern winds are predominant here. On average, precipitation occurs on 80-90 days per year, with rain and snow accounting for approximately half each. Snowfall begins at the end of September and lasts the whole winter; the snowfalls are minor and last for only a short time. By the end of winter the snow depth does not exceed 30-40cm.

BUILDING WINTER ROADS

The Sentachan mine is located in a remote region with limited vehicle access. From February until April, a winter road becomes the only ground-based access route. The rest of the year, the mine can be reached by helicopter only.

Traditionally, the production season in Sentachan begins in November and ends in April of the following year. Technical resources and the necessary supply of diesel fuel are purchased and delivered by road at the end of the previous season. Active preparation for the production season starts in September when the mine is reactivated, and all the necessary supplies for the mine operations and workers’ accommodation are delivered with helicopters.

To bring fuel and other materials to the Sentachan mine as well as transport the mined ore, GPM annually lays a 700km winter road from the town of Elginsky to the settlement of Sentachan. More than 600km of the road is laid through the frozen beds of the Elgi, Utachan and Adycha rivers.

The company’s special crew starts laying the winter road in February using cross-country vehicles, tractor-mounted dozers and all-wheel bulldozers. A vehicle column is accompanied by a relocatable trailer for personnel and a fuel filling truck. The carriageway is wider than 6m to allow trailer-truck traffic. The work is only performed during daylight hours.

Along with laying the road, the crew gathers a full set of measurements – they measure the thickness of snow cover, ice, characteristics of the ice structure and depth of the water bodies and determine the weight-carrying capacity of the ice. The ice thickness is measured with a wireless ice-detector and by drilling holes in a checkerboard pattern along the road. The average construction process lasts for up to three weeks.

For the entire period from February to April, a support crew maintains the winter road. This crew is responsible for controlling the road condition, timely cleaning of the snow blockades, arranging side-roads if necessary, and providing technical support to the transport vehicles.

MINING

The technology used for ore extraction at both the Sarylakh and Sentachan mines is almost identical. Like any country with a long mining history, Russia has regulations that stipulate procedures for extracting deposits of this type.

To mine the deposit, which has low-profile steeply dipping veins, GPM utilises shrinkage stope mining to extract the ore blocks. This ensures optimal results in productivity, ore extraction in terms of both volume and quality, use of consumables and overall cost of mining. Operational blocks are placed along the strike and measure 30-50m long by 50m high.

Access to the Sentachan deposit is gained through two inclined shafts. Shaft 1 is the main underground shaft designed for lifting ore. The shaft is equipped by a cable lift with a car and rail haulage. Shaft 2 is an auxiliary shaft designed to transport people, materials and equipment.

PRODUCTION OF CONCENTRATE

The ore extracted from the Sentachan and Sarylakh deposits is transported to the Sarylakh processing plant to produce antimony concentrate. The Sarylakh plant is located 10km away from the town of Ust-Nera, 65km away from the Sarylakh deposit and 1,100km from Yakutsk, the capital of Yakutia.

The technological process consists of several stages: grinding, gravitation, flotation, hydrometallurgical processing of the gravity concentrate, thickening, filtration and drying of the flotation concentrate.

The band conveyor delivers the ore from the bunker for grinding. Grinding is done in two stages: in a semi-autogenous mill and then in a ball mill.
After grinding, the substance undergoes gravity processing to separate free gold and decrease the gold content in the flotation concentrate. After classification in hydrocyclones, the gold sand is fed into jigging machines and then onto concentrating tables. Drainage liquid from hydrocyclones is directed for flotation. Then the concentrate undergoes thickening and drying.

The final product, gold-bearing antimony concentrate, is transported in large bags from the Sarylakh plant to the Magadan port, where it is dispatched by sea to customers.

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