Process Of Gold Mining In Eagle River Mine

Eagle River mill exterior

The Eagle River mine complex is located near the north shore of Lake Superior 50 kilometres west of Wawa in Ontario Canada, the Eagle River complex includes the underground Eagle River mine, the open-pit Mishi mine, and the Eagle River mill.

In 1994 the Eagle River property was purchased by River Gold Mines Ltd to consolidate ownership of the Eagle River property. On February 1, 2006, River Gold Mines Ltd. merged with Wesdome Gold Mines Inc, to create Wesdome Gold Mines Ltd. (WDO-TSX).

Preproduction development at  Eagle River property commenced in 1995 and the first gold bar was poured on October 17, 1995.  Commercial production Eagle River  mine was declared January 1, 1996 with net of gold produced during the preproduction period, amounted to $15.5 million, from production  28,571 tonnes at a grade of 10.56 g/t of gold,  with 9,700 Gold Ounces  during Pre-Production

Mineral Ore Deposit In Eagle River Mine

Gold bearing quartz veins in the Eagle River mine

The Eagle River orebody deposit is a vertically dipping vein type deposit hosted in an Archean greenstone belt, vein type deposit along a regional deformation zone with discrete brittle, ductile shears localized along lithological contacts. It consists of a series of quartz vein lenses which to date have been traced over a strikelength of 2.5 km and to a depth of 650 metres.

Gold-bearing quartz is highly strained and recrystallized commonly displaying stylolytic textures. Gold occurs at the quartz grain boundaries and in the stylolites. Gold predates the straining of the quartz.

Gold bearing quartz veins in the Eagle River mine deposit constitute a structural corridor within an elliptical quartz diorite stock with dimensions of 1.8 kilometres east-west and 0.5 kilometres north-south and are predominantly hosted by sub-vertically

Gold bearing quartz veins in the Eagle River mine deposit consists of several zones. Quartz veins deposit in the Zones 2,3,6,7 and 8 Eagle River mine constitute different segments of the overall shear zone corridor and each have their own grade characteristic. The bulk of the historic production mine has come from Zone 8 and Zone 6,which are entirely within the intrusive quartz diorite, while Zone 2 mineralization is hosted in sheared mafic volcanic rocks just east of the stock.

In Zone 8 is characterized by a series of thick, white laminated quartz vein lenses. The veins vary in thickness from one metre to 15 metres, but average about 2.5 metres. Commonly only portions of this vein system can be selectively mined with mining widths varying between 1.2 and 7.5 metres. And the gold grade has averaged about 8 grams / tonne of gold with individual stoping blocks ranging from 5 - 12 grams / tonne of gold

Gold is concentrated in highly strained quartz of grey colour and in sericite-chlorite lamellae with accessory sulphide minerals including pyrite, pyrrhotite, galena, sphalerite, and chalcopyrite.

Quartz veins deposit in the Zone 6 is provided the economic backbone of the  Eagle River mine, because this Zone of its Quartz veins deposit high-grade. Mineral gold ore high-grade averaging 12 to 18 grams / tonne of gold and has very competent wall rocks.

The 650 Zone is in a sub-parallel southern splay from the shear hosting Zone 6, which continues eastward into volcanic rocks and hosts the 2 zone. Both the 650 and 2 Zones are characterized by sheeted veins of laminated white quartz ranging in thickness from 1.5 to 6.5 metres. These zones have good grades of 10 to 15 grams / tonne of gold

Reserves And Resources Eagle River Mine

Mining geology Eagle River located in the central portion of the Mishibishu Greenstone belt, which is a broad arcuate belt with about 60 km long and up to 18 km wide. This belt is part of the 2.7 billion year old Wawa-Abitibi Subprovince.

This age-correlative Subprovince of the Superior Province stretches east to Val d’Or, Quebec, and includes the famous prolific gold mining camps of Timmins, Kirkland Lake, Noranda, Cadillac, Malartic and Val d’Or.

Total proven and probable reserves at the Eagle River mine as at December 31, 2014, were 816 000 t grading 10.1 g/t of gold.

Total proven and probable reserves at the Mishi mine as at December 31, 2014, were 1.79-million tonnes at 2.1 g/t of gold.

Resources: Total inferred resources at the Eagle River mine as at December 31, 2014, were 292 000 t grading 8.5 g/t of gold.

Total inferred resources at the Mishi mine as at December 31, 2014, were 764 000 t grading 2.4 g/t of gold. Indicated resources were 3.69-million tonnes grading 2.1 g/t of gold.

Total indicated resources at the Mishi mine as at December 31, 2014, were 567 000 t grading 4.5 g/t of gold. Inferred resources were 437 000 t grading 5.8 g/t of gold.

Process Of Gold Mining In Eagle River Mine

Common Core at Eagle River

From 1996 to 2001, the primary mining method in Eagle River is underground mine was shrinkage stoping, but since 2002 it has been sublevel long-hole stoping. This method has increased production volumes at the expense of higher dilution and development costs.

The Eagle River  mine is accessed through a ramp system and a 580 metres shaft with a loading pocket at 460 metres. Currently, the deepest mining level is 720 metres, and underground access is established at the 150 metres level

Operation mining at Mishi is a Open Pit mining

Operation mining at Mishi is a Open Pit mining operation using conventional 5 m benches. By using a giant shovel, ore is loaded and then transported by haul trucks to stockpiles for processing plant

The Eagle River milling complex is situated 10 km north of the Eagle River mine and 2 km east of the Mishi mine. The mill has demonstrated historical capacity of 1 000 t/d.

The mill in Eagle River mine employ the Merrill-Crowe zinc precipitation process for mineral ore recovery . The Merrill–Crowe Process is a separation technique for removing gold from a cyanide solution.

The Merrill–Crowe Process is a separation technique for removing gold from a cyanide solution. The solution is separated from the ore by methods such as filtration and counter current decantation. Afterwards a very clear solution is achieved by using pre-coated filters applying diatomaceous earth.

Oxygen is then removed by passing the solution through a vacuum de-aeration column. Zinc dust is added to the clarified, de-aerated solution which precipitates the gold; zinc having a higher affinity for the cyanide ion than gold.

Other precious metals, silver, and base metals, like copper, will also precipitate, if present The gold precipitate (mixed with zinc dust) is then filtered out of the solution, and the zinc dust and gold are mixed with sulfuric acid to dissolve the zinc.

The zinc precipitate is refined into doré bars averaging 80-85% gold. These are shipped to the Royal Canadian Mint for final refining. Approximately 1 ounce of by-product silver is produced for each 10 ounces of gold.

Processing facilities also use gravity circuit (Knelson Concentrator), the gravity concentrate averages 70% gold from Eagle River mine and the Eagle River ore leaches well and is free of deleterious elements.

The Knelson concentrator utilizes the principles of centrifuge to enhance the gravitational force experienced by feed particles, which aids in the separation process mineral ore based on particle density.