Third-party Mine Waste Clean-up
Our Golden Sunlight mine in Montana initiated a program to remove and process gold and silver bearing materials from non-Barrick abandoned mine sites near its operation. Currently they have seven contracts for the transportation of historic mine materials to the plant for processing and they have completed contracts with many other public land ore sources. Several of the projects were on priority clean-up schedules for various state and federal agencies. Removing these materials reduces the environmental impact to groundwater from the legacy sites and the additional processing increases mine production, which supports jobs and economic activity in the area. The program has also saved taxpayers hundreds of thousands of dollars in environmental cleanup.
Emissions, Effluents and Waste
Please see Climate Change for a discussion on our greenhouse gas emissions.
Dust and Particulate Matter: Dust is the most common air emission at Barrick’s operations. We suppress dust emissions from roads, crushers and conveyor belt systems through the application of water to roads, the operation of mist sprays and dust collection systems at point sources, and the application of chemical surfactants at some locations.
Sulphur and Nitrogen Oxides: These emissions are most often controlled by the use of filters, scrubbers and other pollution control devices. Information on SOx and NOx emissions is routinely collected in Canada, Australia, and the USA and submitted to national databases. In other jurisdictions, our mines may not routinely collect these data where there are no permit requirements to do so.
Mercury: At a number of operations, mercury air emissions are released during the processing of mercury-containing ore. These emissions are controlled by filters and scrubbers. We are now closing out a five-year mercury abatement program at those sites, which has included a comprehensive program to measure emissions, and the installation of greater controls to significantly reduce or eliminate them. In 2011, 5.4 metric tons of mercury emissions were released to air. Over 98 percent of these emissions come from four operations; one in North America, one in South America and two in the Australia-Pacific region.
Ozone Depleting Substances: Barrick operations do not manufacture ozone depleting substances, nor equipment that would use them. We also do not use materials that contain ozone depleting substances, except for fire extinguishers and some refrigerants and machine shop solvents, therefore emissions of these substances are minimal.
Barrick recycles and reuses water at most sites. We have 19 operations that are zero-discharge sites. However, we do have seven operations and nine other properties that release mine-impacted water to the environment once it meets water quality standards or permit conditions. To ensure that discharged water meets local legal, regulatory and permitting requirements we use sophisticated technology to monitor water quality and quantity prior to discharge. We also monitor groundwater and surface waterways downstream of our operations to ensure we are not having a negative impact on the local environment.
Water is discharged under permit at seven operating mines. In 2011, 73.1 million cubic meters of water was discharged from these properties once it met water quality standards. Eight closed properties and one project also discharge treated water to the environment. The total water discharged under permit from these properties in 2011 was 21.4 million cubic meters.
Water sampling ensures that we only discharge water when it meets permit requirements or water quality standards.
A number of non-process wastes are generated each year at our operations. These wastes may differ by region and by operation, but typically include laboratory assay waste, scrap metals, waste oils, cans and bottles, tires and office and camp waste. As much as possible, we try to recycle these wastes, however this is not always possible at some of our remote sites or at operations located in countries where recycling is not available. Non-hazardous waste which is not recycled is usually landfilled (either in municipal landfills or landfills constructed on the mine property) or incinerated. In 2011, 76,400 tonnes of non-hazardous waste were landfilled and 397,000 tonnes (mostly scrap metals) were recycled. Hazardous waste is addressed below.
Mining involves the removal of ore, the rock which contains economically-recoverable amounts of desired metals. To access the ore deposits, waste rock – the rock which does not contain economically recoverable amounts of desired metals – must be removed. As waste rock may contain various amounts of metals that are naturally present in minerals, it must be properly managed to reduce the risk of pollution, such as acid rock drainage and metals leaching. Waste rock can be placed into engineered facilities which can be contoured, covered with soil and revegetated, or it can be returned to completed open pits or underground mines for permanent storage. At some sites, non-reactive waste rock can be used to construct road beds or dams. In 2011, we deposited over 450 million metric tons of waste rock into engineered facilities, underground workings or into open pits.
Depending on the type of rock, the minerals in the rock and other geologic properties, the ore may be crushed, placed on large, leak-proof liners and chemically leached to extract the desired metals (called heap leaching), or it may be crushed further, mixed with water and chemicals to form a slurry and sent through a processing plant to extract the desired metals. Some of our mines contain both heap leach and process plant operations to recover gold, silver and copper.
The crushed ore in our heap leach facilities is usually the size of gravel, and this material remains after the desired metals have been extracted and all the leach solution has been recovered. At the end of operations, these facilities are normally recontoured and capped with a multi-layered soil cover that prevents rainwater infiltration and allows revegetation. The leak-proof liners underlying the heap leach facilities prevent seepage into the natural ground, and any residual seepage, captured by the liners after closure, is treated to meet water quality standards before being released to the environment.
Tailings are the finely-ground rock particles, usually the size of fine sand and silt, which remain after the crushed and slurried ore has been sent through our processing plants for removal of the desired metals. Tailings slurry is most often pumped to a tailings storage facility (TSF). We try to recover as much of the process water and residual chemicals as possible beforehand for re-use in our processing plants. We also recover water from our tailings storage facilities for re-use in processing. In 2011, we deposited 57 million metric tons of tailings into engineered storage facilities.
Barrick designs, operates and closes waste rock storage facilities, heap leach facilities and tailings storage facilities to internationally-accepted current best available practice, and complies with regulatory requirements for safety and environmental protection. We ensure that the technical, social, environmental and economic requirements of the site and materials are met, and that we honour the commitments made to our stakeholders. We developed a Tailings Management Standard in 2011. It will be implemented at our sites in 2012 and will, in future, direct the design, construction and management of our tailings facilities.
All design components and the overall designs of our storage facilities are subject to detailed risk assessments and critical review by fully-qualified engineers, scientists and socio-economic experts. In addition to daily inspections by fully-trained site staff, our active tailings facilities are inspected annually by the Engineer of Record or a similarly-qualified professional engineer. We also conduct regular corporate inspections and contract internationally recognized experts to provide independent performance reviews of our operating and closed tailings facilities.
We are developing, and have in place at several mines, processes to reduce the water content in our tailings and to lessen our mine footprint. These processes currently include thickening tailings to the consistency of paste before delivering to the tailings storage facility, storing tailings in completed open pits and mixing tailings with cement before backfilling in underground workings. At one of our operations, tailings are blended with crushed ore and sent to the heap leach facility for additional metals recovery.
At our Porgera mine in Papua New Guinea, we deposit tailings material into a nearby river under permit. More information about Porgera and riverine tailings disposal is presented in Significant Environmental Issues.
Barrick has implemented preventative management processes at its operations where the waste rock, heap leach and / or tailings have demonstrated the potential to generate acid rock drainage (ARD) and metals leaching. We are a member of the International Network for Acid Prevention (INAP), an organization which works to address this global mining issue. In 2011, we participated in the ongoing revision of the INAP Global Acid Rock Drainage (GARD) Guide which aims to be a world-wide reference for ARD prevention. Consolidating the vast global knowledge on ARD management into a single document was not an easy undertaking and occurred over several years. In order to create a truly global guide, experts from several countries contributed their knowledge to the development of the Guide. The GARD Guide will be updated periodically as knowledge increases. The first revision is focusing on four specific chapters: Characterization, Prediction, Prevention and Mitigation, and Treatment. The update will be completed by spring, 2012.
Barrick generates hazardous waste from our operations. These wastes include batteries, fluorescent lights, oils, solvents and laboratory assay wastes. The types of hazardous wastes vary among our sites; however all are recycled or disposed of in licensed waste facilities. In 2011, 14,800 cubic meters of liquid hazardous waste and 6,500 metric tons of solid hazardous wastes were disposed of or recycled according to the appropriate regulation.