Macraes

The Macraes open pit gold mine is located 100 kilometres north of Dunedin in the Otago Region on the South Island of New Zealand. It is the largest operating gold mine in New Zealand and is both owned and operated by international gold mining company, OceanaGold Corporation.

Macraes Open pit Mine Includes the Frasers Underground Operation
The Macraes gold mine, that has been in operation since 1990, includes the
Frasers underground gold mine that began gold production in early 2008. The Frasers underground mine was developed to target ore extension of the Macraes gold deposit. The Macraes ore body being developed by the Frasers underground operation is a dip-down extension that is open at depth. Mining here is concentrated on the higher grade ore hosted within the hanging wall. Since the Macraes mine was commissioned it has produced more than three million ounces of gold.

Macraes has Life of Mine to 2018
The gold resource at the Macraes gold mining operation totals 6.38 million ounces with gold reserves standing at 1.47 million ounces. The mine has an expected life to 2018 although this may be shortened to 2017 if world gold prices remain depressed. Gold production averages around 145,000 ounces a year and low gold prices do not encourage vigerous exploration drilling to continue that could target even deeper extensions of the Macrae deposit, despite the objective of identifying and developing extra underground opportunities along the strike of mineralisation showing considerable promise. Up until the present time exploration has also been focused on possible mineable tragets on the surface along the Macraes line of strike.

Macraes ore Processed at Nearby Gold Processing Plant
Ore from the Macraes operation is processed at the adjacent gold processing plant that incorporates a pressure oxidation plant to processes sulphide ore. This plant is one of only three other such plants in the southern hemisphere. Ore coming into the Macraes gold processing plant is subjected to being crushed, a grinding flotation process, fine grinding, pressure oxidation CIL (carbon-in-leach) elution and electro winning before it is smelted. Refactory ore has to be subjected to multistage processing in order to increase its recovery rate. Refactory concentrate originating from OceanGold's Reefton gold processing plant is taken to the Macraes plant by rail and road so it can be treated by means of the autoclave pressure oxidation and carbon in cyanide leaching process.

Earth Slip Temporarily Halts Work at Macraes Gold Mine
In April 2014 the Macraes open pit gold mine was temporarily shut down following a massive earth slip at the mine's west wall following heavy rainfall. The earthfall resulted in a large volume of rock sliding 100 metres into the mine. There were no open pit miners working onsite at the time of the earthfall. Staff working at the underground mine at the time of the slip were taken from the site by helicopter as road access was cut off. All underground workers were safely brought to the surface and no injuries were incurred. The underground operation was not effected by the rock-fall apart from access being blocked. The processing plant continued working by treating stockpiled ore while it awaited normal production to resume. Earlier in the year the Macraes mine workforce had been cut by 25 percent as a result of low gold prices.