Location and History

Buryatzoloto (Irokinda and Zun-Holba mines)

Buryatzoloto comprises the underground gold mines of Irokinda and Zun-Holba in the Republic of Buryatia in the Russian Federation.

Irokinda is located in the Buryatia Republic, approximately 75 km from the town of Taksimo, where the Baikal- Amur railway station and airport are located. The mine is accessible from an all-season road. Production began in 1985.

Zun-Holba is also located in the Buryatia Republic, approximately 315 km from the village of Kultuk, which is on the Trans-Siberian railway, and 400 km from the city of Irkutsk. It is also accessible by an all-season road. Production began in 1986.

These assets were acquired by Nordgold in late 2008 as part of the controlling interest in High River Gold. Nordgold holds a 90.6% voting interest in Buryatzoloto.

In 2015, Buryatzoloto delivered stable production and strong cost performance. The mines produced 112.7 thousand ounces.

Operating and Financial Highlights

2015 2014 2014 2013 2012 2011 2010
Ore mined (kt) 683 694 689 686 660 630
Ore processed (kt) 691 686 668 695 680 661
Grade (g/t) 5.18 5.58 4.72 5.04 6.48 6.87
Recovery (%) 92.3 92.9 92.2 93.3 92.9 91.7
Gold production (koz) 112.7 119.7 98.5 108.9 134.3 136.1
Gold sold (koz) 122.8 109.3 98.4 108.9 134.4 143.8
Average realised gold price per ounce sold (US$/oz) 1,172 1,281 1,382 1,665 1,563 1,236
Revenue (US$/m) 143.9 140.0 136.0 181.3 210.0 177.6
EBITDA (US$/m) 67.4 48.7 26.3 80.7 126.5 90.7
Total Cash Cost (US$/oz) 629 793 993 812 672 522
AISC (US$/oz) 780 992 1,425 - - -

Ore Reserves and Mineral Resources Summary (31 December 2015)

Category Ore (Kt) Grade (g/t) Au (Koz)
RESERVES (Zun-Holba)
Proven and Probable 1,0875.04176
RESOURCES (Zun-Holba)
Measured and Indicated 1,41410.24 456
Inferred 11917.68 68
RESERVES (Irokinda)
Proven and Probable 1,5876.05309
RESOURCES (Irokinda)
Measured and Indicated 95510.57325
Inferred 6047.47 145


For more information, please see Mineral Resources and Ore ReservesPress Release

Technology

The Irokinda and Zun-Holba mines are both relatively mature underground operations. Both contain a processing plants, each with crushing, grinding, gravity and flotation circuits. The Zun-Holba plant also contains a CIL circuit and related facilities. For processing, there are two crushing stages and two grinding stages using ball mills, followed by gravity separation, which produces concentrates for both the gravity and flotation circuits. The gravity circuit is used to recover free gold, after which smelting produces doré bars. Flotation is used to recover finer gold particles into a flotation concentrate. At the end of 2014, Buryatzoloto employed approximately 3,000 people.

Buryatzoloto
Buryatzoloto comprises the underground gold mines of Irokinda and Zun-Holba.
Milling and Classification
Ore is sourced from underground operations using conventional mining methods involving drilling and blasting, followed by load and haul to the run of mine (ROM) stockpiles where it is either directly fed to the primary crusher or stockpiled. The ore is crushed to a P80 15 mm using a two or three-stage crushing circuit with screening. The crushed material is then conveyed to a grinding circuit consisting of deferent size ball mills.
Gravity Circuit
Both Irokinda and Zun-Holba mines use a gravity circuit to recover free gold before ore is milled finer for floatation. Primary concentration takes place in a centrifugal concentrator followed by cleaning of concentrates using several stages of shaking tables. This allows the plant to produce a gravity concentrate ready for direct smelting. Gravity gold recovery account for up to 20% at Zun-Holba and 60% at Irokinda.
FLOTATION
Flotation is a method of separating minerals depending on their ability to attach to air bubbles. The flotation process consists of producing a mineral concentrate through the use of chemical conditioning agents followed by intense agitation and air-sparging of the agitated ore slurry to produce a mineral rich foam concentrate. At Zun-Holba and Irokinda after grinding and gravity recovery circuit all the ore goes to flotation. The flotation concentrates from the Irokinda is shipped to the CIP plant at the Zun-Holba mine for further treatment by cyanidation and sorption.
CYANIDE LEACHING AND SORPTION
At Zun-Holba mine flotation concentrate is carried out in a carbon in pulp (CIP) circuit. During the CIP or CIL stage, pulp flows through several tanks where sodium cyanide and oxygen have been added to dissolve gold into solution. In the absorption stage, this pulp flows through several tanks containing activated carbon. Gold then attaches onto the activated carbon, which is moved counter current to the pulp, while screens separate the barren pulp from the gold-loaded carbon.
Elution
The gold loaded carbon is removed and washed before undergoing desorption. Desorption is achieved by introducing the gold loaded carbon to a solution of sodium cyanide at a high temperature (>110°C) and pressure. This results in the reversal of the attachment process, with the gold detaching from the carbon back into solution. This produces a small volume of solution with a high gold concentration.
Electrowinning
The gold loaded eluate solution that emerges from the desorption process is passed through electrowinning cells, where gold is deposited onto the cells cathodes.
Smelting
The cathodes then undergo a smelting process, further refining the gold and leading to the eventual production of doré bars for transport to a refinery. Dore bar is an alloy of gold, silver, copper and other metals containing between 50%-90% gold.

2016 Deliveries

  • Further operational improvement initiatives will continue at both the Buryatzoloto mines of Irokinda and Zun-Holba, targeting the same volume and grade of mining material at improved efficiencies. The recovery will increase slightly in 2016.
  • Irokinda will continue Decline development and ore production from lower horizons of Vein #3 and Vein Serebryakovskaya.
  • Irokinda plans to increase plant efficiency in 2016 through reconstruction of the crushing complex scheduled for completion in Q1 2016, which will enable an increase in crushing volume and a reduction in the size of crushed material.
  • Optimisation of the gravity circuit, scheduled for completion in Q2 2016, will result in recovery improvement. Weightometers for the mining fleet and conveyors will be constructed in 2016 to increase the accuracy of operational statistics.
  • The mine will target Ore Reserve replacement from exploration drilling at the high-grade Vysokaya Vein. Irokinda will also start development of the Medvegya and Sluchainaya Veins. In 2016, the mine plans to continue the study of Veins 2&3, Hrebtovaya, Serebryakovskaya and Petrovskaya aiming at increasing resources.
  • At Zun-Holba, mechanised development of the Zun-Holba 2 Decline will be accelerated in 2016 in order to access the Deep horizons. Dewatering infrastructure required for the existing Shaft levels will be commissioned on the 1290 horizon.
  • The mine will also continue to develop exploration Declines from which deep targets in the Dalnaya, Kvartsevaya, Kontaktovoe and Severnoe-3 zones can be drilled out in the most efficient manner. Ore drilled in these targets will be incorporated in mineable reserves as drilling is completed in 2016.
  • The Zun-Holba mine in 2016 will be focused on the implementation of mechanisation projects, aimed at increasing the productivity of mining with a special focus on mining quality and effective reporting systems.
  • Mining of Kvartsevaya and Kontaktovoe ore bodies from the Decline should commence in 2016.

CONTACTS

Olga Ulyeva


Head of Media Relations
tel.+7 495 644 44 73 #707 6632

ROMAN MEZHUEV

RECRUITMENT MANAGER
tel.+7 495 644 44 73

OLEG BAZALEEV

HEAD OF SUSTAINABLE DEVELOPMENT PROJECTS
tel.+7 495 644 4473 #707 6746