Apple, USGS develop rock-to-metal ratio
Study shows how much rock and ore is mined for 25 metals Metal Tech News - May 5, 2022
Last updated 7/12/2022 at 2:04pm
How much rock must be moved to produce the metals in an Apple iPhone, Tesla Model 3 electric vehicle or any other product that requires mined commodities (i.e., nearly everything)? Apple teamed up with the United States Geological Survey to develop a "rock-to-metal ratio" that makes it easier to answer that question.
Metals are essential to every aspect of modern life. Even a bowl of oatmeal requires these fundamental building materials to grow, ship, and process this heart-healthy breakfast – metal is even represented in the name of fiber-rich steel-cut oats.
The new rock-to-metal ratio developed by USGS and Apple provides a metric for better understanding how much ore and waste rock must be mined, moved, and processed to produce a refined unit of 25 different metals and semi-metals.
Nedal Nassar, chief of the Minerals Intelligence Research Section at the USGS National Minerals Information Center and lead author of the study, said this kind of information has many potential uses.
"For instance, manufacturing companies could use our data as one of several deciding factors on where to source minerals and or which materials they use in their products," he said.
Considering that more than 60 different minerals and metals go into making the average smartphone, the rock-to-metals data could be especially useful to tech companies.
An in-depth dive into the metals that go into smartphones can be read at Miracle of metals make smartphones smart in the inaugural January 1, 2020 edition of Metal Tech News.
A company like Apple, which already invests heavily in cleaner and greener sources of the materials that go into its products, could use the rock-to-metals ratio to determine the best metals to use in its high-tech devices. Or, if an alternative cannot be used without giving up quality or performance, know where it can invest in recycling, alternative sources, or more sustainable to produce the irreplaceable mineral or metal.
"As Apple continues to pioneer new innovations in recycling, the rock-to-metal ratio will help advance scientific understanding of the value of using more recycled materials and accelerate progress toward a circular economy," said Sarah Chandler, Apple's senior director of Environment and Supply Chain Innovation.
The tech giant is particularly interested in utilizing this metric to measure the environmental footprint of different mines producing any given metal to help ensure that it utilizes the most responsible operations to provide it with the mined materials needed for its iPhones, iPads, AirPods, and other electronics devices.
Toward this goal, USGS analyzed the rock-to-metal ratio of 25 mined materials that are used by virtually every manufacturing industry in the global economy – aluminum, chromium, cobalt, copper, gallium, gold, iridium, iron, lithium, magnesium, molybdenum, nickel, palladium, platinum, rhodium, ruthenium, silicon, silver, tantalum, tin, titanium, tungsten, vanadium, zinc, and zirconium.
The analysis shows there is a wide range in rock-to-metal ratios among different mineral commodities. At the low end of the spectrum is iron ore – one of the most heavily mined commodities on Earth – which has a rock-to-metal ratio of 9-to-1. This means that for every one metric ton of iron processed, nine metric tons of waste rock and ore must be moved. At the other end lies gold, which as a rock-to-metals ratio of 3 million-to-1, or about three metric tons of ore and waste rock, must be moved and processed to produce one gram of this precious metal.
"These iron and gold ratios are the global averages for these particular commodities," said Nassar. "We found wide variability among the ratios for each mineral commodity based on the particular mining operation that it was extracted from."
The study also found that roughly 37.6 billion metric tons of rock, or enough to build 7,000 Great Pyramids of Giza, is being moved each year to produce the 25 mined commodities analyzed.
While the rock-to-metal ratio can provide some clues to the environmental impacts of various mining operations around the world, Nassar is quick to add that "this is only one piece of a larger puzzle, and the rock-to-metal ratio needs to be used in conjunction with other data to make informed decisions about mineral sourcing or material choice."
The full study can be read at: https://pubs.acs.org/doi/10.1021/acs.est.1c07875