Mining involves the removal and processing of ore — the rock containing economically recoverable amounts of desired metals.
To access the ore deposits, waste rock must be removed and stored in waste rock dumps and, after processing, mine tailings may be produced and stored in engineered tailings storage facilities (TSFs).
If not properly managed, TSFs can fail and lead to harmful impacts on the environment and nearby communities. This is why we have established internal requirements based on international best practices, and why these facilities are carefully designed and monitored by internal and external experts.
Following the disaster at the Samarco mine in Brazil, the ICMM launched a review of the TSF standards, critical controls and emergency preparedness of its 23 members. In Canada, the Mining Association of Canada undertook an extensive re-assessment of its TSF management practices (already described as ‘best available practice’) and made that report public. Barrick has been active in both efforts, which helps demonstrate that the mining industry is taking concerted action to improve industry practice and mitigate the risk of TSF failures.
For more information on these initiatives see the ICMM and MAC websites.
Barrick has a Tailings and Heap Leach Management Standard that requires our sites to locate, design, construct, operate and close their TSFs in compliance with applicable laws and regulations and in alignment with accepted international practice.
The Standard establishes the minimum geotechnical, hydrological, hydrogeological and environmental design, construction, operation and closure criteria and procedures for Barrick’s TSFs.
Our target is to have zero TSF-related incidents
We conduct daily routine inspections at our operations and annual dam safety inspections are conducted by the Engineer of Record. Independent third-party reviews are conducted at a minimum of every two to four years at high-risk TSFs and independent assurance audits of TSFs are conducted every one to three years.
Over 80 independent reviews of our TSFs have been conducted since 1998
At some sites, gold ore is processed using heap leaching. With heap leaching, ore is crushed to approximately the size of large gravel particles and placed on a contained composite liner system. The ore is then irrigated with a chemical solution which dissolves the desired metals, typically sodium cyanide (for gold recovery) or sulfuric acid (for copper recovery). The composite liner – a combination of clay soils and impermeable synthetic membranes – is designed to ensure that no solution escapes the leach pad. Equally important, the composite liner system also allows Barrick to recover the leach solution carrying the dissolved metals for further processing. In critical areas, we often double the synthetic liner system. Leak detection, down gradient monitoring and other safety features are also typical of our designs. The crushed ore in heap leach facilities (HLFs) remains after the copper or gold has been extracted and the leach solution has been recovered.
At the end of operations, the heap leach piles are rinsed or recirculated and allowed to drain down, ensuring both maximum gold or copper recovery and environmental protection. Any residual seepage, captured by the liner system after closure, is treated to meet water-quality standards before being released to the environment. HLFs are then re-contoured and capped with a multi-layered soil cover that minimizes rainwater infiltration and allows revegetation.
Management of Barrick’s heap leach pads are covered under the Tailings and Heap Leach Management Standard. The Standard establishes the minimum geotechnical, hydrological, hydrogeological and environmental design, construction, operation and closure criteria and procedures for Barrick’s TSFs and HLFs.
Mining involves the extraction of ore – the rock containing economically-recoverable amounts of desired metals – from the host rock. The waste rock – the rock that does not contain economically recoverable amounts of desired metals – must also be removed, though mining plans minimize as much as possible the amount of waste rock relative to extracted ore.
235 million tonnes of waste rock were stored in 2015
Because waste rock naturally contains concentrations of potentially harmful elements, the material must be properly managed to reduce the risk of pollution associated with acid rock drainage (ARD) and/or metals leaching (ML).
Waste rock can be placed into engineered waste rock storage facilities which, once full, can be re-contoured, covered with soil and revegetated, or the material can be returned to completed open pits or underground mines for permanent storage. At some sites, non-reactive waste rock – material that does not have the potential to generate ARD/ML – may be used to construct road beds or tailings dams. At other sites, waste rock may be co-disposed in tailings storage facilities and submerged to significantly limit geochemical reaction rates, thus minimizing ARD/ML.
Barrick has implemented mitigation management at its operations where the waste rock, heap leach, and/or tailings have demonstrated the potential to generate ARD/ML.
Mercury is a naturally occurring element that is present, at some operations, in the ore we process. As a result of processing, mercury is separated from the ore. Using a risk-based approach for each operation, we place controls on equipment to collect elemental mercury and to trap most mercury emissions to air where needed.
Mercury requires effective management due to potential environmental and human health risks. We promote responsible management of mercury by following our Environmental Management System and the ICMM position statement on mercury risk management. Barrick has a cross-functional Mercury Task Force that is currently focused on mercury management.
142 tonnes of mercury were produced in 2015
It is our practice to ship elemental mercury and mercury compounds to a reputable refiner or stabilizer or to store it securely on site. For mercury shipments, strict handling, packaging and transportation procedures are in place to protect both people and the environment. Consistent with U.S. law, we ceased the export of elemental mercury from U.S. facilities in January 2013.
A number of non-process wastes are generated each year at our operations. These wastes may differ by country and by operation but typically include scrap metals, waste oils, cans and bottles, spent tires, and office and camp waste. While we try to recycle these wastes as much as possible, this is not always feasible at some of our remote sites or at operations located in countries where recycling is not available. Non-hazardous waste that is not recycled is usually landfilled (either in municipal landfills or landfills constructed on the mine property) or incinerated, on or off the site.
We also generate a relatively small amount of hazardous waste each year. These wastes include batteries, fluorescent lights, certain oils, solvents, electronic waste and laboratory assay wastes. As with process materials, the types of hazardous wastes vary among our sites; however, all are recycled or disposed of according to the appropriate regulation in the countries where we operate.
Our vision is the generation of wealth through responsible mining — wealth for our owners, our people, and the countries and communities with which we partner.
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