Air Quality in Kalgoorlie-Boulder
Local industry, households and the climate of our region all influence the quality of the air. There are a number of sources which contribute to local air quality, including mining emissions from both gold roasting and nickel smelting, cars, planes, and households, particularly in winter from wood heaters. The dry and windy semi-arid desert environment can also result in very dusty conditions, as well as storage of mine tailings near the city, unsealed roads, degraded land and roasting of ore concentrate close to town.
Historically, air quality in the City of Kalgoorlie-Boulder was poor. The formation of KCGM in 1989 provided the opportunity for improved air quality through:
- The establishment of a “green belt” between the mine and the City to improve the visual appearance and reduce dust generation from degraded bare land.
- A phased reduction of in-town roasting and the establishment of a roaster at a location that minimised the impacts of sulphur dioxide on residential areas.
Coupled with these, improved management practices have resulted in significant improvement in air quality in the City of Kalgoorlie-Boulder since the 1990’s.
The Fimiston Air Quality Management Plan (FAQMP) was initially developed by KCGM in 2007 as part of the Fimiston Gold Mine Operations Extension (Stage 3) and Mine Closure Planning Public Environmental Review (PER) to integrate a number of management plans that cover various air quality aspects of the Fimiston Operations, including the DMMP.
The 2019 FAQMP review was approved by OEPA in November 2019.
Dust Monitoring and Management
The Goldfields Dust Abatement Committee (GDAC) was formed in the 1970’s. This committee fenced off areas around the city, planted trees and monitored dust levels. Then in 1994 the Kalgoorlie-Boulder Land care Group (KBULG) continued on with similar work and KCGM formed its own team of Environmental officers who monitor dust levels and make sure KCGM and its contractors meet the requirements of the DEC.
KCGM, along with KBULG, has also completed extensive rehabilitation work. A “Green Belt” of around 730 hectares, including 210,000 trees now exists between the mining area and the city.
KCGM’s Dust Monitoring and Management Programme (DMMP) was developed and implemented in accordance with conditions set by the Minister for Environment. The first version of the DMMP was developed in 1993 and revised in 2001 to reflect blasting dust monitoring and management changes. It was again revised in 2004 to meet requirements of the Southern Landform Extension Project Section 45C Approval.
The major sources of dust emissions associated with the Fimiston Operations include drilling and blasting; loading and unloading of ore and waste rock; vehicle generated dust; wind erosion; crushing; and conveying.
There are also many natural and anthropogenic (manmade) sources of particulate emissions in the Goldfields Region and it is not unusual to have regional dust storms which can result in significant ambient dust concentrations (PM10) over a wide area. KCGM uses data from its dust monitoring network (seven continuous PM10 monitors and two wind speed and direction monitors) to assess the potential contribution of mining operations to any elevated concentrations.
KCGM undertakes continuous dust monitoring at the Hannan’s Golf Course (HGC), Boulder Shire Yard (BSY), Hewitt Street (HEW), Clancy Street (CLY), Hopkins Street (HOP), Mt Charlotte (MTC) and Metals Exploration Yard (MEX) sites. The MTC and MEX monitors are located near existing wind speed and wind direction monitoring stations. The HGC site is primarily used as a control/background monitoring site for dust as it is located some 4.5 km from the Fimiston Operations. It is considered to be representative of the local environment and data enables comparison of background levels with the other monitoring sites.
The 24-hour average PM10 concentrations measured at each site are contained in the KCGM Dust Monitoring Report which is available on the KCGM website within 24 hours of the data being recorded.
KCGM have undertaken a number of measures to reduce dust emissions associated with the Fimiston Operations and to ensure that the 24-hour average PM10 concentrations are less than the NEPM guidelines at the monitoring locations, as well as reducing the occurrence of short term high concentration events that occur as a result of its operations. Specific measures include:
- Monitoring current and forecast wind conditions using daily forecasts from the BoM and real time wind speed and direction monitoring data to minimise off-site dust emissions as a result of blasting;
- Use of water trucks and water cannons in areas that produce dust such as haul roads, service corridors and other active surfaces. Fresh water is used on areas to be rehabilitated;
- Undertake visual inspections for dust generation on a regular basis;
- Use of additional dust control measures where practical (e.g. a dust binding agent);
- Progressive rehabilitation to minimise exposed areas;
- Suspending work in a particular area or for a nominated activity as deemed necessary based on inspections, dust monitoring levels, public feedback or prevailing wind conditions;
- Ensuring that all contractors and staff undertake inductions which include raising awareness of the importance of dust control;
- Ensuring dust monitoring is undertaken and the results of this monitoring are reviewed; and
- Ongoing consultation with stakeholders to determine the success of the dust management measures.
Sulphur Dioxide Elimination
The reduction of atmospheric stack emissions associated with the operation of the roasters at Gidji has been a long-term focus of KCGM. Following the formation of KCGM in 1989, the establishment of the Gidji Processing Plant resulted in the decommissioning of the remaining three in-town roasters. This resulted in a significant reduction in sulphur dioxide (SO2) levels in the City of Kalgoorlie-Boulder.
The closure of the two roasters at Gidji in 2015 marks the end of a long history of using roasting to extract gold from the Golden Mile. Golden Mile ore is unique, with most of the gold intricately bound in various sulphide minerals such as pyrite. Roasting is still the most efficient and cost effective way to maximise gold recovery from sulphides, however this process has become more restricted due to environmental constraints associated with the atmospheric stack emissions of SO2 and mercury (Hg). As part of a long term commitment to continuous improvement, KCGM has been examining alternative forms of concentrate treatment since the 1990’s.
Since early 2001, KCGM has successfully operated a 10 tonnes per hour (tph) Ultra Fine Grinding (UFG) Mill at Gidji to supplement its roaster capacity for the treatment of concentrate. A second 10 tph UFG Mill was installed at Fimiston in 2002. These were the first commercial trial of UFG Mills in sulphide gold mining.
The UFG Mills have now proven that they are a viable alternative for treating gold concentrate, allowing KCGM to fully replace roasting and eliminate atmospheric stack emissions at the Gidji Processing Plant.
Download KCGM Air Quality Information Sheet