Every object that humans use either is made from earth resources or relies on earth resources for its production and distribution, said Corale Brierley, a founder of Brierley Consultancy. Oil and gas provide fuel for transportation and electricity for homes and businesses. Groundwater provides drinking and irrigation water. Sand and gravel are indispensable for construction. Copper is essential for electrical equipment and other devices. Electronic materials contain rare earth elements. Fertilizers consist of mined potassium and phosphorus. Geothermal energy is an emerging source of renewable energy. The earth even provides for storage and disposal of wastes.
New technologies are also changing how people think about and use earth resources. In recent decades, hydraulic fracturing and horizontal drilling have radically changed the production of energy. New techniques make it possible to drill miles into the earth beneath 10,000 feet of water-bearing rock to obtain petroleum. Tunnel boring machines are digging passages all over the world.
In the 1970s, the experience with Love Canal in Niagara Falls, New York, provided valuable lessons about environmental pollution. “We have to be extremely careful about what we put in the soil because it can pollute our groundwater,” said Brierley. Since then, research on the analysis and transport of contaminants has helped avoid similar disasters.
Solvent extraction now allows for the mining of much lower grade ore. The combination of solvent extraction and a technique known as electrowinning can yield a copper product that is 99.999 percent pure, Brierley observed. Biomining uses microorganisms to extract certain metals from earth materials, with 20 percent of the world’s mined copper now being produced through this technique.
And although some people think sustainability in mining is an oxymoron, “it isn’t,” she said, “because technology and engineering play such a huge role in maintaining our ability to extract these metals deeper and deeper in the earth and lower and lower in grade.”
Technology also has made mining safer. The continuous miner has greatly reduced the number of miners who have to work underground. Many mining operations now use driverless trucks that rely on sophisticated technology to prevent injury and death to workers. In situ mining, in which minerals are extracted from rocks underground without transporting the rocks to the surface, could further reduce the exposure of workers and others to hazardous substances and situations.
TECHNOLOGIES FOR THE FUTURE
The next 50 years will demand equally dramatic improvements, said Brierley. In situ mining needs to be further developed to reduce the footprint created by mining on the earth’s surface. In situ extraction can take advantage of the higher temperatures with depth in the earth, because extracting minerals tends to be easier at higher temperatures.
It also will be safer and more sustainable and will reduce the amounts of waste produced.
Technologies that enable people to “see” underground will further boost sustainability and safety. Already, ground-penetrating radar and three-dimensional seismic technology can reveal things such as objects buried under Stonehenge and the structure of volcanoes. But existing technologies still have limitations. For example, Big Bertha, the largest tunnel-boring machine in the world, got stuck under Seattle because it could not “see” a steel pipe in its path.
“What we need is a Google Map of the interior of the Earth so that we can see the geological and structural features underground,” said Brierley. Just as biomedical technologies can see inside the body in real time, new technologies could visualize the fluids in the interior of the Earth with real-time accuracy.
With such technologies, the world could become a different place, Brierley concluded. Geothermal energy could reduce the need for fossil fuels. Earthquakes could be moderated or controlled. Carbon dioxide in the atmosphere could be stored underground. “Whether it is groundwater, whether it is geothermal energy, whether it is tunneling for transportation, whether it is mining, or for any of these other things, we have to be able to see what we are doing. That is where I see the great innovation technologically.”
The Human Origins of Biomining
Some of the technologies Brierley discussed at the forum were of nonstandard, even humble origins. The development of biomining occurred in part because of a young woman who grew up on a cattle ranch in Montana, who rode her horse to a one-room schoolhouse and hated to clean the chicken coop. Her mother told her, “If you would go to college and if you would marry the right man, you won’t have to ever clean another chicken coop.” That young woman did go to college and met a young PhD student, and together they studied the microorganisms at hot springs in Yellowstone National Park, many of which have become extremely important in the mining industry. For their contributions to biomining, James and Corale Brierley were elected to membership in the National Academy of Engineering.
Brierley said that she never thought of herself as an engineer—she was a microbiologist by background. “I was just doing engineering work and applying microorganisms to mining. It wasn’t until I got elected to the NAE that I discovered I was an engineer.”
