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| Young Davidson mining operation |
Young Davidson mine is one of mining operation from AuRico Gold and among Canada’s largest underground gold mines. The 100%-owned Young-Davidson gold mine in northern Ontario is expected to produce 200,000 ounces per year by 2015. AuRico Gold has projects in Canada, Mexico and Australia and five operating properties including the Ocampo mine in Chihuahua State, the El Chanate mine in Sonora State, the El Cubo mine in Guanajuato State, as well as the Fosterville and Stawell gold mines in Victoria, Australia.
The Young Davidson gold mine is located near the town of Matachewan, approximately 60 km west of Kirkland Lake in Northern Ontario US and within the southwestern part of the Abitibi Greenstone Belt. The mine is centrally located between Timmins, Kirkland Lake, North Bay and Sudbury. The Young Davidson mine property consists of contiguous mineral leases and claims totaling 11,000 acres, and is situated on the site of two past producing mines that produced one million ounces from 1934-1957.
Geology
GEOLOGY AND MINERALIZATION IN YOUNG DAVIDSON MINE
Geology
The
deposit Young-Davidson lies within the south-western section of the
Abitibi Greenstone Belt, one of the largest greenstone belts in the
world with historic production of 160 million ounces of gold . The belt
is characterised by a diverse and complex spectrum of volcanic,
sedimentary and plutonic rocks that have been metamorphosed to
greenschist facies grade. Regionally, the rocks maintain the amphibolite
facies grade.
The
volcanic rocks, ranging between rhyolitic and komatiitic, exist as
mafic to felsic volcanic cycles. Sedimentary rocks are hosted as
intravolcanic sequences and as a sequence that overlies the
intravolcanic sequence.
A
broad spectrum of pre-tectonic, syntectonic and post-tectonic intrusive
rocks occur as mafic to felsic. All lithologies are cut by diabase
dikes belonging to the late Proterozoic age and trending mostly
north-east.
Within
the Abitibi Greenstone belt, a series of complex deformation events
have taken place including fabricless folding and faulting, faulting and
ductile shearing. Faulting and ductile shearing resulted in the
formation of large, crustal-scale structures, generally east-west
trending. The structures took the form of a lozenge-like pattern.
The
Larder Lake-Cadillac Fault Zone cuts through the project area.
Characterised by chlorite-talc-carbonate schist, the zone dips
sub-vertically and has an east-west strike.
Mineralisation
Gold mineralization at Young-Davidson is associated with a syenite intrusive rock (a quartz granite). Within this syenite, the gold mineralization is associated with a stockwork of quartz veinlets and narrow quartz veins, rarely greater than a few centimetres thick that are within a broader halo of disseminated pyrite and potassic alteration.
The three key Archean sedimentary rock groups found within the district are the Pontiac Group, the Porcupine Group and the Timiskaming Group. The Pontiac Group is the oldest and exists as thick assemblages within the Québec bedrock. The Porcupine Group consists of turbiditic siltstones and greywackes found interbedded within the Larder Lake Group volcanic rocks. The Timiskiming Group along with turbidite and iron formations overlie the Porcupine Group.
The southern limit of the Abitibi belt is defined by overlapping Huronian Proterozoic sedimentary rocks that are co-related to the Gowganda Formation tillite. The Huronian unconformity in the project zone is categorised by post-Archean dike rocks including the Matachewan diabase and the Nipissing Diabase.
Within the belt, the open pit and underground gold resources are hosted largely within syenite rocks. Syenite-hosted gold mineralisation includes a stockwork of quartz veinlets and fine quartz veins found within a wider halo of largely spread pyrite.
The narrower quartz veinlets are glass textured making the contained gold highly visible. The mineralisation zones are easily distinguishable as they are characterised by brick red to pink K-feldspar rich syenite.
Historic mining demonstrated the continuity of mineralization from surface to a depth of approximately 500 metres.Mineralization is known to extend beyond 1,500 metres below surface (orebody open at depth); however, current drilling below this level will not be initiated until suitable underground drill platforms become available. Other mines along the Kirkland-Larder Lake trend were mined to depths of over 2,000 metres.
GOLD MINING AND PROCESSING IN YOUNG DAVIDSON MINE
The underground mine at Young Davidson is accessed via shaft and ramp. The existing MCM shaft is expected to reach its ultimate depth of 1,500 metres in 2015 to provide for the hoisting of personnel, materials, ore and waste.
The sinking of the Northgate shaft was completed down to the mid-shaft loading pocket in 2013, which accesses the first eight years of mine production.
The underground mine at Young Davidson continues on developing vertical access in the underground mine below that of the mid-shaft loading pocket, to an eventual depth of 1,500 metres. The mine will also be accessed by a ramp, which will be extended to the bottom of the mine from the existing exploration ramp, currently at a depth of 900 metres below surface.
The Young-Davidson underground mine has been designed for low operating costs through the use of large modern equipment, gravity movement of ore and waste through raises, shaft hoisting, minimal ore and waste re-handling, high productivity bulk mining methods (long hole open stoping) and paste backfill. The mine operates scooptrams to load, haul and transfer stope production to the ore pass system from where it is hoisted to the surface via 18 tonne skips.
The underground ore and stockpiled open pit ore is processing through and 8,000 tpd single stage semi-autogenous grinding circuit with a gravity circuit followed by flotation. The flotation concentrate is further ground and leached in a conventional carbon-in-leach. The flotation tailings are also leached in a carbon-in-leach circuit. The gold is recovered from the carbon followed by electro-winning and pouring doré bars. The Young Davidson carbon-in-leach tailings are treated with the SO2/Air cyanide destruction method. The paste backfill plant was commissioned in 2014 and is capable of supplying paste fill to the underground voids at a rate in excess of 8,000 tonnes per day.
Gold mineralization at Young-Davidson is associated with a syenite intrusive rock (a quartz granite). Within this syenite, the gold mineralization is associated with a stockwork of quartz veinlets and narrow quartz veins, rarely greater than a few centimetres thick that are within a broader halo of disseminated pyrite and potassic alteration.
The three key Archean sedimentary rock groups found within the district are the Pontiac Group, the Porcupine Group and the Timiskaming Group. The Pontiac Group is the oldest and exists as thick assemblages within the Québec bedrock. The Porcupine Group consists of turbiditic siltstones and greywackes found interbedded within the Larder Lake Group volcanic rocks. The Timiskiming Group along with turbidite and iron formations overlie the Porcupine Group.
The southern limit of the Abitibi belt is defined by overlapping Huronian Proterozoic sedimentary rocks that are co-related to the Gowganda Formation tillite. The Huronian unconformity in the project zone is categorised by post-Archean dike rocks including the Matachewan diabase and the Nipissing Diabase.
Within the belt, the open pit and underground gold resources are hosted largely within syenite rocks. Syenite-hosted gold mineralisation includes a stockwork of quartz veinlets and fine quartz veins found within a wider halo of largely spread pyrite.
The narrower quartz veinlets are glass textured making the contained gold highly visible. The mineralisation zones are easily distinguishable as they are characterised by brick red to pink K-feldspar rich syenite.
Historic mining demonstrated the continuity of mineralization from surface to a depth of approximately 500 metres.Mineralization is known to extend beyond 1,500 metres below surface (orebody open at depth); however, current drilling below this level will not be initiated until suitable underground drill platforms become available. Other mines along the Kirkland-Larder Lake trend were mined to depths of over 2,000 metres.
GOLD MINING AND PROCESSING IN YOUNG DAVIDSON MINE
The underground mine at Young Davidson is accessed via shaft and ramp. The existing MCM shaft is expected to reach its ultimate depth of 1,500 metres in 2015 to provide for the hoisting of personnel, materials, ore and waste.
The sinking of the Northgate shaft was completed down to the mid-shaft loading pocket in 2013, which accesses the first eight years of mine production.
The underground mine at Young Davidson continues on developing vertical access in the underground mine below that of the mid-shaft loading pocket, to an eventual depth of 1,500 metres. The mine will also be accessed by a ramp, which will be extended to the bottom of the mine from the existing exploration ramp, currently at a depth of 900 metres below surface.
The Young-Davidson underground mine has been designed for low operating costs through the use of large modern equipment, gravity movement of ore and waste through raises, shaft hoisting, minimal ore and waste re-handling, high productivity bulk mining methods (long hole open stoping) and paste backfill. The mine operates scooptrams to load, haul and transfer stope production to the ore pass system from where it is hoisted to the surface via 18 tonne skips.
The underground ore and stockpiled open pit ore is processing through and 8,000 tpd single stage semi-autogenous grinding circuit with a gravity circuit followed by flotation. The flotation concentrate is further ground and leached in a conventional carbon-in-leach. The flotation tailings are also leached in a carbon-in-leach circuit. The gold is recovered from the carbon followed by electro-winning and pouring doré bars. The Young Davidson carbon-in-leach tailings are treated with the SO2/Air cyanide destruction method. The paste backfill plant was commissioned in 2014 and is capable of supplying paste fill to the underground voids at a rate in excess of 8,000 tonnes per day.
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