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| Introduction MNV Novoshirokinskoye Mayskoye Taseevskoye Exploration |
MNV
Overview
Geology
Mineral Resources & Ore Reserves
Mining
Mineral Processing
| Overview
Mnogovershinnoe is located in the Nikolaevsk area of the Khabarovsk Territory in the far-east of the Russian Federation. The mine is located some 650 km north of the city of Khabarovsk and is accessed from Nikolaevsk-na-Amure, the principal regional centre, via a 132 km long gravel road. The Mnogovershinnoe deposit was discovered in 1959 and detailed exploration commenced in 1963. Preliminary construction started in 1979, the mineral processing facilities were constructed between 1990 and 1993 and preliminary production started in 1991. Between 1991 and the present day the mine has produced some 700,000 oz of gold. |
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The Group owns 100% of the MNV joint-stock company, which has a licence for the extraction of gold ore valid until December 2018. Operations at MNV consist of both underground and open-pit mining of several high grade gold deposits. In addition, MNV has its own gold processing plant. MNV was initially brought into production by its previous owners in 1991 and operated until 1997, when the mine was closed due to poor technical and financial performance and a lack of funds for reconstruction and development. Following a change of ownership and the introduction of the current management team, gold mining and gold extraction recommenced in 1999 under the direction of the new management team. Subsequent capital investment in mining and metallurgical equipment, has meant that the technical performance of the mine has significantly improved over the last five years.
| Geology
The Mnogovershinnoe gold deposits are located at the junction of the Amgun synclinorium and the East Sikote-Alin volcanic belt. The area is characterised by numerous faults which control the location and orientation of the volcanics, intrusives and gold and silver mineralisation. The mineralisation covers an area of some 120 km2 which is divided equally into two parts by a north-west trending fault. The basement rocks consists of Mesozoic sandstones, shales and clay. Both these basement sediments and the overlying volcanics are intruded by dykes of granodiorite, granite and porphyries. Major north-east orientated fractures containing large quartz veins and veinlets control the mineralisation, the geometries of which are further complicated by later north-west orientated faults. |
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The ore bodies at Mnogovershinnoe are located within two zones, the Main Zone and the Intermediate Zone. The Main Zone is some 5.8 km long and contains the Central, Upper and Reindeer ore bodies. The Intermediate Zone is some 6.2 km long and is located 1.5 km north-west of the Main Zone and contains the Intermediate I and II ore bodies together with the South, Flank, North, Deep, Quiet and Boulder ore bodies. The overall width of the two zones is some 2.5 km. All the ore bodies strike north-east and dip to the north-west. Generally both ore body thickness and gold grade distribution is highly irregular.
| The Main Zone is confined to a steeply dipping fault with a north-east strike. It consists of a central quartz vein system surrounded by a zone of veinlet-impregnated silicification. The thickness of the total zone varies from 10 m to 60 m. The zone structure is complicated by numerous post-mineralisation faults and intrusions. |
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The Intermediate Zone is also confined to a steeply dipping fault with a north-east strike and consists of a thick quartz vein surrounded by a halo of quartz veinlets. The total zone thickness varies between 20 m and 80 m. The Intermediate Zone is subdivided into blocks by a number of north-west faults with vertical displacement.
The Mnogovershinnoe ore bodies are characterised as gold-chalcedony-quartz, low sulphide, veins. Quartz constitutes more than 95% of the ore bodies. Gold is distributed irregularly in the form of fine disseminated impregnations, small individual pockets and thin veinlets.
The majority (92-96%) of the gold and silver (80-90%) occurs in a free form amenable to standard cyanidation leaching. Some amounts also occur as fine inclusions in quartz, other rock-forming minerals and sulphides.
Visible gold is uncommon and cyanide leaching test work confirms that the gold is non-refractory, with extraction levels of 95% being achievable at standard grind parameters.
Mineral Resources & Ore Reserves
| Mnogovershinnoe Mineral Resource Statement | |||
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Tonnage
(kt) |
Au Grade
(g/t) |
Ag Content
(koz) |
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| B+ C1 (Indicated) |
6,579
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9.0
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1,915
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| C2 (Inferred) |
2,181
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10.7
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752
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| Total |
8,760
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9.5
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2,667
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| Mnogovershinnoe Ore Reserve Statement | |||
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Tonnage
(kt) |
Au Grade
(g/t) |
Ag Content
(koz) |
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| B (Proved) |
1,145
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7.3
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270
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| C1 (Probable) |
6,198
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8.2
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1,628
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| Total |
7,343
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8.0
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1,898
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Open Pit
Mining is standard open pit benching. Waste benches of 10 m and ore benches of 5 m are drilled using Russian-made drills with hole diameters of 125 mm to 250 mm. Holes are charged with Anfo(Ammonium Nitrate Fuel Oil) and the blasting ratio is 0.25 kg/t of rock (ore and waste). The overall pit slopes are between 45º and 55º. The mountainous topography enables the pits to be designed to minimise pumping and maximise the advantages of downhill haul gradients.
Primary loading is done using small (4-5 m3) electric rope shovels. Belaz trucks of 27 t and 40 t capacity are used for ore and waste transport.
Underground
The mining method currently in use is long hole sub-level caving with an interval of 14 m between sub-levels. 100 mm diameter long holes are drilled up from each sub-level using a Russian drill rig. Development is undertaken using modern mobile drill rigs and LHDs.
Ore is loaded from the draw points using modern diesel-powered 3.5m3 LHDs. The ore is tipped into a central ore pass system where it gravitates into a series of loading chutes on the No11 level. Ore and waste is loaded from the chutes into 2.6 m3 wagons which are hauled to the tip at the mouth of the adit by a locomotive powered by electricity from an overhead power line. Ore and waste is loaded at the tip by a conventional front end loader into 40 t off-road trucks and transported 3.6 km to the mill or the waste dump.
| Mineral Processing Pre-blended ore is delivered to the plant feed hopper by trucks, which either direct tip or stockpile for subsequent feeding via the front-end loader. Ore is withdrawn from the base of the bin by an apron feeder, which is then fed through a jaw crusher. Crushed ore is conveyed to a series of 14 feed hoppers. |
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The milling circuit comprises two 7.0 m x 2.3 m SAG mills each fitted with 1,600 kw motors and two 3.6 m x 4.0 m ball mills each fitted with 1,000 kw motors. The normal running format is to operate one SAG mill with both ball mills.
| SAG discharge pulp passes into a spiral classifier. The spiral overflow is pumped through a series of hydro cyclones generating a final product of 85% minus 74 microns. Cyclone overflow is pumped to the cyanide leach circuit. Following pH adjustment, sodium cyanide is added at a rate of between 0.8 to 1.0 kg per tonne of ore and the pulp is then leached for approximately 10 hours. The pulp then passes through the resin absorption circuit, where leaching of gold from the ore and absorption onto the resin particles continues for a further 10 to 12 hours. |
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Loaded resin is periodically removed from the leaching circuit and treated through the desorption and electro winning system to generate plated cathode gold. This gold is then smelted to produce bullion bars, which are shipped off site for final refining.
Leached pulp containing approximately 300 to 400 ppm residual cyanide is neutralised using the calcium hypochlorite technique, prior to being deposited in a tailings facility approximately 4 km from the plant. All decanted water is recycled from the dam and returned to the plant; any additional make up water requirements are drawn from a nearby stream.
| © 2005 Highland Gold Mining Ltd. |