By Jane Goldsmith
16 July, 2015
IN March 2014, Kalgoorlie Consolidated Gold Mines (KCGM) poured its 16 millionth ounce of gold from Fimiston open pit –widely known as the Super Pit. This milestone was achieved in time for the company’s anniversary celebrations to commemorate 25 years of activity at the historic site.
Since incorporating, KCGM has produced about 800,000oz per annum of gold from an 8.8 million ounces gold reserve, yielding 2g of gold per tonne on average.
The Newmont-Barrick joint venture produces about 8 per cent of Australia’s total gold output, and for much of Australia’s contemporary mining history, was the country’s biggest gold producer. KCGM relinquished its long-held title to Newmont’s Boddington mine in the final quarter of 2012.
Early Kalgoorlie was a story of prospectors fossicking for gold in WA’s eastern grounds. In June 1893, Irish prospectors Paddy Hannan, Thomas Flanagan and Dan Shea discovered what would become the basis of KCGM’s operation, finding nearly 100oz of alluvial gold at the base of Mt Charlotte in the Kalgoorlie-Boulder region. The discovery went down as a singular defining moment in WA history, and set in motion Australia’s second major gold boom.
People travelled from across Australia and the world to seek their fortunes in an area that would, with time, become known as WA’s Golden Mile. The influx boosted WA’s population and brought great wealth to the state. Capital works, including roads and railways and the construction of CY O’Connor’s Goldfields Water Supply Scheme also came about, and the increasing diversity of the population pushed WA to join the Commonwealth of Australia during Federation in 1901; a previously unforeseen move.
By 1903, the Golden Mile hosted 49 operating mines, 100 headframes and more than 3000km of underground workings.
Almost eighty years later, WA-businessman Alan Bond began buying up individual leases from the smaller operators, working to amalgamate them into one big company and one big pit, to extract gold at a lower cost. Although his company failed in this venture, Mr Bond’s ambition was later completed in 1989 by KCGM, who successfully formed the Golden Mile Super Pit.
KCGM was incorporated to manage the Fimiston Super Pit assets and operations on behalf of joint venture partners, Normandy Australia and Homestake Gold of Australia, and across the early 90s, constructed large, modern processing plants Fimiston and Gidji to manage the gold ore.
In December 2001, Canadian company Barrick Gold merged with Homestake and shortly after (February 2002), Normandy merged with Newmont Mining. Barrick and Newmont have since remained the equal owners of KCGM and the Golden Mile leases – although in April 2015, Barrick announced it would relinquish its bureaucratic control to Newmont in an effort to streamline future decision-making.
Since 1893, the Golden Mile, 550km east of Perth, has produced about 58moz of gold. In 2014, it still remained a globally important site, holding its position as the world’s fifth largest gold producing region.
Today, the 3.5km long, 1.5km wide and more than 600m deep Fimiston Super Pit is accompanied by a sister operation, the Mt Charlotte underground mine. The complete operation has a projected mine life to 2019 although low-grade stockpile processing is forecast to continue until 2029. At its expected 2019 closure, the Super Pit will have reached 700m in depth.
Barrick’s March quarter 2015 report showed its share of production was 59,000oz at an all-in sustaining cost of US$1271/oz. Total output for the quarter fell to 118,000oz from 162,000oz in December, which Barrick attributed to a 16 day shutdown in February. The shutdown saw 600 additional contractors working alongside KCGM’s standard personnel to complete a milling and girth gearing upgrade at Fimiston plant.
In early June, KCGM announced changes to its gold processing infrastructure, replacing the Gidji processing plant’s nearly-30-year-old roasters with a 30tph ultra fine grinding (UFG) mill. The upgrade is a part of KCGM’s $98 million Emissions Reduction project, and will work to eliminate atmospheric stack emissions from Gidji.
KCGM’s acting general manager Ian Butler said UFG mill installation was an environmentally-conscious upgrade which would significantly change how sulphide gold concentrate was processed for the mine’s remaining life.
“Golden Mile ore is unique, with most of the gold intricately bound in various sulphide minerals such as pyrite. Roasting is still the most effective method of extracting gold, however as part of KCGM’s long term commitment to continuous improvement, we have looked at alternative forms of concentrate treatment since the 1990s,” Mr Butler said.
“KCGM was the first in the Australian gold industry to adopt the UFG Isa mill when we installed a 10tph mill at Gidji in 2000, followed by a second 10tph mill at the Fimiston processing plant in 2002.
“The UFG mills have now proven that they are a viable alternative for treating gold concentrate, allowing KCGM to fully replace roasting at the Gidji processing plant.”
In February 2014, KCGM confirmed its plans to finish mining the Golden Mile, including the design, rehabilitation and monitoring of the progressive closures of Fimiston open pit, the Fimiston and Gidji processing plants and the Mt Charlotte underground mine infrastructure.
As Kalgoorlie-Boulder’s biggest employer, it also noted the possible impact the closure could have on the local community.
“Kalgoorlie-Boulder has been a mining community since 1893 and its residents are realists,” it said.
“The community is aware that gold is a limited resource and all mines have a finite lifespan. When the Fimiston open pit was first started, its projected operating life was just 14 years, which would have meant a 2003 closure date.
“By the time its projected closure date of 2029 has been reached, KCGM will have been a vital part of the Goldfields for 40 years. With an iconic landmark in the Super Pit, its rehabilitated landscapes a living inheritance and its historic status as the largest mining company ever to operate on the Golden Mile, the legacy of Kalgoorlie Consolidated Gold Mines will live on long after its has left the Goldfields.”