Gold was first discovered in the Kanowna area by Irish prospector Jerry McAuliffe in 1893. Nearly one million ounces of gold were produced in the ensuing gold rush which lasted until the onset of the First World War. Despite several episodes of modern exploration throughout the 1970’s and 1980’s, the Kanowna Belle deposit was not discovered until late 1989 by Delta Gold NL. Open pit mining commenced in 1993, with full underground production achieved in 1998.
Ownership of the Kanowna Belle mine has changed hands several times during its operation: Delta Gold merged with Goldfields Limited in 2001 to form Auriongold; Placer Dome Asia Pacific completed the acquisition of Auriongold in 2002; Barrick Gold Corp acquired Placer Dome in 2006. The Kanowna Belle operations were acquired by Northern Star Resources Limited on 1 March 2014.
Mineralisation is mainly hosted within a large porphyritic granodiorite body (Kanowna Belle Porphyry) that has intruded a sequence of sedimentary and volcaniclastic rocks. A zone of intense structural disruption (Fitzroy Shear Zone) separates the deposit into hangingwall and footwall structural domains, and is the primary control on gold distribution. Gold mineralisation is locally associated with quartz-carbonate stockwork veins, breccia zones, sulphide-quartz-carbonate stringers and sheeted vein arrays. The generally tabular enveloping surface to mineralisation dips steeply to the south, has a high plunge to strike ratio and remains open at depth.
The mining method at Kanowna is a form of modified open stoping which is sequenced and driven on a stope by stope basis by geotechnical considerations. The open stopes are back-filled with paste utilising tailings from the Kanowna Belle Mill.
The ore is accessed on a level spacing of 30 metres, with development of footwall, and ore drives to enable longhole open stoping. The mine is subdivided vertically in mining blocks of nominally 150 to 250 vertical metres, (3 to 5 Mt).
The Kanowna Belle processing facilities are located adjacent to the Kanowna Belle mine and are designed to handle approximately 1.8 million tonnes of feed per annum. The plant has the capability to treat both refractory and free milling ores, through the flotation circuit and associated concentrate roaster circuit, including carbon-in-leach (CIL) gold recovery, or bypassing the flotation circuit and going directly to a CIL circuit that is designed to treat flotation tails.