Goldstrike mine in northeastern Nevada is one of the largest gold mines in the world. In 2016, the mine produced 1.1 million ounces of gold. Only two other operations—the Grasberg mine in Indonesia and the Muruntau mine in Uzbekistan—produced more.
On September 25, 2016, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite captured this false-color image of the mine. Vegetation appears red. Water is dark blue. Bare rock appears in shades of brown and gray. The most noticeable feature is the Betze-Post open-pit mine, which is managed by Barrick Gold Corporation and has a depth of more than 500 meters (1,600 feet). Smaller open-pit mines operated by other companies are also visible northwest and southeast of the Betze-Post pit.
Trucks transport ore from the bottom of the pit to nearby processing facilities, where gold is concentrated and extracted. On average, there is roughly 0.1 ounce of gold per ton of ore. Processing typically involves crushing ore into powder, exposing it to high temperatures and pressures, and leaching material out of liquid slurries. Leftover slurry is stored in tailing ponds, where solids settle out. In addition to its large open-pit mine, Goldstrike has two underground mines that also produce ore.
One of the key issues facing mines is water management. Open-pit mining requires pumping groundwater out of adjacent aquifers in order to prevent the pit from flooding. At Goldstrike, operators pump several thousand gallons of groundwater per minute to keep the water table below the level of the pit. Some of this water is used to process ore, but some of it gets used in other ways or pumped backed into the ground. For instance, the water used to irrigate the circular fields southwest of the Betze-Post pit comes from groundwater pumping related to the mining.
While the company that operates Goldstrike mine maintains a network of monitoring wells and stream gauges to track how mine activities are affecting the aquifer, it also has used Interferometric synthetic aperture radar (InSAR) data from satellites as part of its monitoring efforts. Since each monitoring well can cost between $300,000 to $500,000, and InSAR offers a big-picture view of the aquifer, a satellite perspective can offer an effective way of monitoring subsidence, uplift, and other changes in the Earth’s crust associated with groundwater pumping, the company noted. InSAR observations show subsidence in areas near the mines and uplift in areas southwest of the mines.
References and Further Reading
- Barrick (2008) Innovative satellite imagery takes water monitoring to the next level. Accessed August 25, 2017.
- Barrick (2014) Nevada Mine Tour. Accessed August 25, 2017.
- Infomine (2008) Goldstrike Mine—Nevada’s Giant Golden Goose. Accessed August 25, 2017.
- Mining Technology Betze-Post Gold Mine, Nevada, United States of America. Accessed June 26, 2017.
- The New York Times (2005, December 30) Drier, Tainted Nevada May Be Legacy of Gold Rush. Accessed August 25, 2017.
- North Nevada Business Weekly (2014, March 10) Barrick invests heavily in new processing. Accessed August 25, 2017.
- Price, J. et al. (2012) Update on Nevada Mining and Production and Exploration. Accessed August 25, 2017.
- Shelp, M. et al. (2011) The Applications of Satellite Based Remote Sensing Techniques in the Hydrological Assessment of Mine Water Supply and Management Systems. Mine Water and the Environment, 30 (4), 242-251.
- U.S. Geological Survey (2005) Changes in Ground-Water Levels in the Carlin Trend Area, North-Central Nevada, 1989-2003. Accessed August 25, 2017.
- Zhan, J. (2012) Mine Dewatering and Water Management at Barrick Goldstrike Mine in the Carlin Trend, Nevada. Accessed August 25, 2017.