Favona, Trio and Correnso underground mines
Late in 2004, construction began on the decline for the Favona underground operation. While some ore was mined during construction, full ore production from stopes began in 2006. Currently ore from underground and from the Martha open pit are both fed to the processing plant and treated alternately.
In January 2012 the Favona Mine had around 23,000 metres of drives, including the decline.
Modern mechanised mining operates from the bottom up. Mining began at Favona at a depth of 335 metres below the surface. Mined out areas (stopes) are backfilled so that we can access upwards the next level of the ore. Filling provides lasting stability and no large voids are left behind – as was common in the historic Martha underground mine.
The Trio underground mine
The Trio project is situated under Union Hill and comprises the Union, Trio and Amaranth veins. Construction of two development drives, 590 metres and 790 metres in length, began in 2010. Access to the Trio Mine is through the Favona portal. Ore production at Trio began in mid 2012. The Trio project will produce around 1 million tonnes of ore for approximately 200,000 oz of gold at 6-7 grams per tonne average grade.
Correnso underground mine
The Correnso project is situated under The East End of Waihi. This project began in November 2014. Please see The Eastender for maps of drives and stopes.