Waihi

Overview

Waihi gold mining operations are located in New Zealand and consist of the Favona underground deposit and the Martha open pit. Trio is another underground deposit that is currently under development (2012). The mine is 100% owned by Newmont Mining Corporation.

Gold and silver were mined at the property between 1890 and 1952. The mine was dormant until the open pit commenced operation in 1987. For older production figures and other info see the Waihi Mine (former name of the mine).

Gold production peaked in 1909. In the period 1879 to 1952, 5.6 million ounces of gold and 38.4 million ounces of silver were recovered from 12 million tonnes of ore.

The Waihi operation produced 97,000 ounces of gold in 2011 and at December 31, 2011 Newmont reported 0.4 million ounces of gold reserves.
 
Open pit mining is done via hydraulic excavator and haul trucks on the steeply dipping vein system which is over 1,600 m in strike length. Underground mining employs the cut and fill mining method.

In August 2011 Newmont Waihi Gold announced Golden Link proposals that have the potential to extend mining in Waihi to 2020. Golden Link comprises the Martha Exploration Project and the Correnso Underground Proposal.

Location

Waihi is located 110 km southeast of Auckland on the North Island of New Zealand.

New Zealand is an island country located in the southwestern Pacific Ocean. The country geographically comprises two main landmasses ‒ that of the North and South Islands ‒ and numerous smaller islands.

Climate is is warm with humid summers and damp winters.

Areas of natural beauty within the Waihi include the Karangahake Gorge, Waihi Beach and the coastline north and south.

Geology & Mineralization

 Waihi is an epithermal gold-silver mineral deposit which is large by world standards. Host rocks are of the andesitic type. Gangue is made of quartz and calcite and mineralization is represented by gold and silver crystallized as electrum, native gold and the silver mineral acanthite.

As of December 2011, proven reserves were estimated at 3.2 Mt grading 0.112 oz/t for 360,000 ounces gold. The average grade of the ore being mined is three grams of gold and 30 grams of silver per tonne.

In August 2011 Newmont Waihi Gold announced Golden Link proposals that have the potential to extend mining in Waihi to 2020. Golden Link comprises the Martha Exploration Project and the Correnso Underground Proposal.

Mining & Operation

Operations consist of the Favona underground deposit and the Martha open pit. Martha open pit is situated in a residential area.

Mining within the open pit is currently focussed on the Martha East Layback, a project that will see mining activity continue until 2014. Open pit mining is done via hydraulic excavator and haul trucks on the steeply dipping vein system which is over 1,600 m in strike length.

Favona's decline began construction in 2004 and it was in full production in 2006. The mining method of choice is cut and fill which provides for mechanized mining to start from the bottom up - the mined out areas are being backfilled. Favona underground operation is due to be completed by the end of 2011.

A new underground project, Trio, can be accessed from the existing Favona portal and has been granted resource and land use consents to proceed. 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.  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. Trio is due for completion in 2014.

Processing

Ore and waste rock are crushed at the surface facilities area prior to transportation along a 2.7 kilometre conveyor. On arrival at the processing plant gold and silver are extracted from the ore using conventional carbon-in-pulp treatment methods.

Waste rock is used to construct an engineered earth embankment to contain the tailings.

A water treatment plant treats excess water prior to discharge.

Environment & Community

Newmont operates in compliance with applicable laws, regulations and other legal requirements. In addition to this mandate, its internal management system includes a global set of performance standards. Its goal is continuous improvement, and it regularly measure itself against these performance criteria to track its progress.