Untitled - PRIME Gold

862005NORILSK NICKEL • ANNUAL REPORT •NORILSK NICKEL • ANNUAL REPORT •200587Oxidized ore processing technologyFrom the sorting yard the ore is delivered to the receivingbunkers from where it is fed into two parallel lines of two stagegrinding and then for sizing. The overflow from the sizingis fed into circular thickeners.The thickened ground pulp is fed to columns for absorptionleaching by sodium cyanide. During the absorption leaching,the gold is diluted and absorbed by the ion exchange resin.After detoxification, the gold saturated resin is fed for regenerationto a chain of columns. Gold bearing regenerate is fedfor electrolysis as a result of which the finest particles of goldsettle on the bottom of electrolytic baths.Gold bearing sludge is filtered, roasted and smelted in inductionfurnaces. The final product is rough gold bars that aresent on to the gold refinery.The rate of gold extraction from oxidized ores is 97.1%.Sulfide ore processing technologyIn sulfide ores, gold is combined with sulfides and is not suitablefor direct cyanidation. For this reason, additional technologicalextraction operations are needed to unlock the gold.Olimpiada MEC was the first in the world to apply bacterialoxidation (biooxidation) technology to unlock gold from refractorysulfide ore in the Far North environment.Sulfide ore, preliminarily crushed and milled into pulp, is fedfor floatation, after which the sulfide floating concentrate isfed for bacterial oxidation in cascades of mechanical air reactorsand the floatation tailings are fed for absorption leachingafter preliminary thickening. After neutralization, the oxidizedconcentrate is also fed for absorption leaching.Otherwise, the technology used for extracting gold from sulfideores is the same as that used in the oxidized ore processingsection.In 2005, the rate of gold extraction from sulfide ores was80.7%.OJSC LenzolotoAlluvial gold depositsThe history of alluvial gold deposit mining in the Bodaibo districtin the north-eastern part of the Irkutsk region beganmore than 150 years ago. Lenzoloto is the largest gold minerin the district.To ensure profitable development of alluvial gold depositswith low gold content, Lenzoloto uses specialized equipment,including 10 dredges, 26 draglines with a bucket volumeof 6 to 20 cubic meters, 18 mining shovels with a capacityof 5 cubic meters, over 200 bulldozers and 86 open-pit dumptrucks.Mining technologiesLenzoloto companies mine gold using both the open-pit andunderground methods. The share of underground mining isvery small (less than 3%).Open-pit method (separate)Stripping operations for the preparation of the mining groundsuse a combination of techniques involving draglines, bulldozersand open-pit dump trucks. Gold bearing sands fromthe grounds are fed to washing plants. The average gold contentin the sands using this method of mining is 0.8–0.9 g/m 3 .Dredging methodThe dredging technology of alluvial gold mining requires theperformance of preparatory works. The peat is stripped,depending on the depth of the productive layer, by bulldozersor by excavation with the use of draglines. The dredgingmethod is the most economically effective in the developmentof alluvial gold deposits and ensures profitable mining providedthat the gold content in sands is approximately 0.3 g/m 3 .Sand extraction technologyGold bearing sands are processed in various types of washingplants with sluice enrichment technology.OJSC Aldanzoloto GRKKuranakh MECThe Kuranakh MEC, a subsidiary of Aldanzoloto GRK, is locatedin the Aldan district of the Republic of Sakha – Yakutia inthe territory of the Eastern Siberia, several kilometers away fromthe Nizhny Kuranakh settlement.Deposits mined and characteristics of oresOver the period of operation, the 11 hard rock gold depositsin the Kuranakh ore field have been considerably affected bymining work. The central parts of the deposits with the moststable parameters of ore bodies and increased gold grade ofores have mainly been exhausted.Total recorded subsoil reserves of the gold deposits in theKuranakh ore field amounted to 61.2 million tonnes of ore(118.5 tonnes of gold) at 1 January 2005 with average goldgrade of 1.94 g/tonne.The following deposits are estimated to have the largestresources:• Delbe (12.2 million tonnes of ore with a gold grade of1.92 g/tonne);• Severnoye (10.0 million tonnes of ore with a gold grade of2.03 g/tonne);• Yakokutskoye (10.0 million tonnes of ore with a gold gradeof 1.69 g/tonne); and• Kanavnoye (8.9 million tonnes of ore with a gold grade of1.76 g/tonne).All the deposits of the Kuranakh ore field have the same geologic,morphologic and lithologic characteristics. The ores areof the quartz pyritous type. The gold from Kuranakh ore fieldis represented mainly by microscopic (0.05–0.001 mm) and submicroscopic(less than 0.1 micron) particles, is present in freestate and genetically combined with sulfides, ironic and quartzhydroxides.Mining technologiesKuranakh ore field deposits are mined using the open pitmethod with drilling and blasting operations. The top downtransportation system is used in the mining work with horizontallayers of up to 10 meters high.In some cases, bulldozer mining or preparation (ripping) of oreis used. Ore is mined by bulldozers in trenches with benchheight of up to 5 meters. Blasting operations are carried outusing the simplest explosives (igdanites).Mining is conducted using SBSh 250 åç rock drills andEKG-5, EKG-8, EKG-10, RH 90 C and Hitachi excavators.Mined rock is transported by HD-1200 open-pit dump trucksand by BelAZ-7540, BelAZ-7555 and BelAZ-75145 dumptrucks.The pit's total annual output of mined rock is approximately11 million m 3 and of mined ore is approximately 3.6 milliontonnes.Ore processing technology used by the Kuranakhgold extracting plantThe ores contained in all the Kuranakh deposits are easilycyanided with a low input of sodium cyanide – up to0.5 kg/tonne, grind size – 95% of minus 0.315 mm class andleaching time of 6–8 hours. The plant uses cyanide leachingtechnology with the absorption of gold in the resin. Heapleaching is commercially used on the Kuranakh ore field ores:in 2006 it is planned to obtain 6,109 ounces of gold at theNadezhny heap leaching section by processing 300 thousandtonnes of ore with an average gold grade of 0.9 g/tonnesand an extraction rate of 70%.LLC Lenskaya Gold Mining CompanyZapadny MECThe Zapadny deposit, mined by Lenskaya Gold MiningCompany, is located in the Bodaibo district of the Irkutskregion and is part of the Sukhoy Log ore field adjacent on itseast side to the largest Russian hard rock gold deposit –Sukhoy Log.Deposit mined and characteristics of oresThe gold mineralization of the deposit is of the vein-disseminatedquartz-pyrite type with low-gold-content quartz-veinbodies. The ores mainly contain placer gold.The mining plan designed for Zapadny MEC states that thereare 4.7 million tonnes of ore in the open pit envelope with anaverage gold grade in commercial ore of 2.77 g/tonne. Thedesign capacity of the Zapadny MEC is 0.8 million tonnes ofore per year.The refining of gold produced by Zapadny MEC is outsourcedto an independent precious metals refinery, the KrasnoyarskPrecious Metals Plant.Mining technologiesThe pit configuration, mining technology and type of equipmentused are determined by ore occurrence patterns, thinnessof ore bodies and relatively low gold grade of the ore.The deposit is mined by the open-pit method. The averagerate of ore and host rock hardness determines the need toconduct drilling and blasting operations in preparing the rockfor excavation.GOLD MINING ASSETS OF MMC NORILSK NICKEL(Polus)9