Kalgoorlie Consolidated Gold Mines (KCGM) Operations is a world class asset located adjacent to the City of Kalgoorlie-Boulder approximately 600 kilometres east of Perth, Western Australia. The KCGM Operations include the Fimiston Open Pit (Super Pit), Mt Charlotte Underground Mine and the Fimiston and Gidji Processing Plants.
The 1893 gold rush resulted in the discovery of the Golden Mile, one of the richest gold deposits in the world. In 1903 there were 49 operating mines, 100 headframes and more than 3,000 kilometres of underground workings on the Golden Mile.
In the 1980’s, WA businessman Alan Bond started to buy up the individual leases along the Golden Mile with the aim to consolidate them into a single company. While Bond’s company failed to complete the takeover, the entire area was combined in 1989. Kalgoorlie Consolidated Gold Mines Pty Ltd (KCGM) was formed to manage the KCGM Operations owned by joint venture parties Normandy Australia Limited and Homestake Gold of Australia Limited.
Existing smaller pits were amalgamated into the Super Pit. All underground operations were phased out except for the Mt Charlotte Underground Mine, and the Fimiston and Gidji processing plants were constructed.
In 2019 KCGM celebrated its 30th anniversary and poured its 50,000th bar of gold, bringing the total produced from the Golden Mile to over 60 million ounces in the 120 years since the lease was first pegged.
Barrick Gold Corporation and Newmont Goldcorp Corporation owned the KCGM Operations in a 50:50 joint venture until November 2019 and January 2020, when they sold their 50:50 interests in the KCGM Operations to Saracen Mineral Holdings Limited (Saracen) and Northern Star respectively. The KCGM Operations became 100% Australian-owned for the first time in its 31-year history on 3 January 2020.
When the merger by Scheme of Arrangement between Northern Star and Saracen was implemented on 12 February 2021, the KCGM Operations became controlled by a single entity, Northern Star, for the first time in its history.
GEOLOGY & MINERALISATION
The Golden Mile at the centre of the Kalgoorlie Goldfield is one of the richest gold deposits in the world.
The Kalgoorlie Goldfield is part of the Norseman-Wiluna Belt, a greenstone belt consisting of volcanic and sedimentary rocks and surrounded by extensive granite. These rocks all belong to the Archaean period of the Earth’s history and the goldfield is between 2.6 and 2.9 billion years old.
The stratigraphy of the Kalgoorlie area consists of a 1,500m thick stratigraphic succession of mafic-ultramafic volcanic rocks that are unconformably overlain by a 3,000m thick succession of volcanic and sedimentary rocks. The volcanic rocks include lavas and pyroclastic flows. This succession is interbedded with siltstone and sandstone, and is unconformably overlain locally by a unit of poorly sorted sandstone and conglomerates.
The deposit is composed of a series of mineralised faults which are known as lodes and were formed by ancient shears, mainly occurring in a host rock known as the Golden Mile Dolerite. There are two main styles of mineralisation:
The Fimiston Style consists of classic Golden Mile lodes with abundant sulphides and tellurides.
The Charlotte Style consists of younger white quartz veins and is typically mined at Mt Charlotte but has been found in other smaller deposits in the area.
More than 1,000 individual ore lodes occur within the Golden Mile, some extending up to 1,800 metres long, 1,200 metres deep and 10 metres wide. They are within an area over 5 kilometres long, 1 kilometre wide and more than 1 kilometre deep.
The KCGM Operations are simple, large-scale mining operations. The vast underground network of historical workings throughout the Golden Mile has shaped the way the Super Pit has been mined during the past 30 years. Mining methods have also been governed by the proximity of the Super Pit to Kalgoorlie-Boulder.
Mining the Super Pit is a carefully planned sequence involving cooperation across a wide range of departments, specialist teams and partner contractors. Each has their part to play, from geology, environment, mine planning and survey teams to drillers, blasting engineers and the giant shovels and haul trucks which transport waste for disposal and ore for processing.
The Fimiston processing plant treats more than 13 million tonnes of ore from Fimiston and Mt Charlotte. The Fimiston plant was commissioned in 1989 and has since undergone two expansions to become one of the largest milling complexes in Australia.