Lithium may store the power that drives out modern mobile world, but it's copper that delivers it. This malleable metal is a vital component in modern homes, electronics and agriculture. But our reliance on copper comes at a steep price, both economically and environmentally.
Copper is quite the miracle metal. It readily conducts electricity (second in ability only to silver), strongly resists corrosion, and can easily take on a variety of shapes and tasks -- everything from your home's plumbing and the circuitry of your car's stereo to utility-scale power transmission lines and industrial fertilisers and pesticides. In fact, nearly half (45 per cent) of all copper consumed goes into home buildings with less than a quarter being used in electronics. This is due in no small part to the economy's shift from production to service industries.
“If you think about electric cars and wind turbines,” Rohan McGowan-Jackson, vice president of innovation and resource development at the Rio Tinto mining company, told Pacific Standard. “They’re all part of this demand for copper. I mean, I drive a Prius. It’s full of copper! The more you move toward a lower-footprint future, the more demand there is for our product.”
Satiating the world's appetite for copper is a massive worldwide industry. Copper mining got its start in the mid 19th century. Last year, the US alone produced 1.15 million tonnes of the ore ($US9 billion worth, 65 per cent of which is consumed domestically in the US) from just 28 mines -- and that total only makes us the fourth largest producer behind Chile, China and Peru. The US has an estimated reserve of another 39 million tonnes of ore stashed under Arizona (which discovered one of the largest reserves in the world 7000 feet underground in 1996), Utah, New Mexico, Nevada and Montana. Only Chile, Australia and Peru have larger reserves.
How Copper is Mined and Refined
173 years after industrial copper mining got its start in the US, we're still using many of the same techniques -- specifically the open-pit method. Since copper ore often occur near the surface and doesn't form veins in hard rock like gold, silver and salt do, tunnelling into the Earth isn't necessary. Instead open pit mining simply removes the valueless soil and minerals above the copper (known as overburden) to access the ore directly.
Once the copper-containing rock is excavated, it's trucked out of the mine for processing. Since copper doesn't form neat little nuggets like gold does, but rather is widely dispersed throughout the unwanted rock (also known as gangue mineral) much like lithium is, the gangue must first be ground to powder. It is then separated from the gangue.
This occurs either through hydrometallurgical liberation, wherein the copper is leached out and concentrated using a menagerie of toxic chemicals, if it is locked up in an oxide ore. Otherwise, if the copper is stuck in a sulfide ore, froth flotation method is employed. Froth flotation, once called ""the single most important operation used for the recovery and upgrading of sulfide ores," uses a number of surfactants and wetting agents to exploit the natural differences in hydrophobic reactions between copper ore and gangue to separate the two.
The Copper Problem
Copper production is a dirty, expensive business. Especially for the surrounding environment. Just getting the unrefined ore out of the ground is a massive effort. Open pit mines demand massive resources, both for energy (they're often powered by coal-burning plants) and for water. What's more, mining operations become less efficient over time. It's easy to pull copper out of a new mine, it's all still near the surface. But eventually you'll have to dig deeper and deeper into the Earth, removing more and more overburden, and travel further up the winding walls of the pit to get to the rim (which requires increasing amounts of time and fuel). Eventually, the law of diminishing returns kicks in, wherein the production costs exceed what you can sell the ore for, and the mine either closes or fallows.
Take the Bingham Canyon Mine in the Oquirrh Mountains, a half our outside of Salt Lake City, Utah for example. It's been open since 1906 and has rapidly expanded over the course of 107 years of operation to 965m deep, 4km wide, and covering 1900 acres including the associated smelter, refinery and water pumping/recycling centre to supply the necessary fluids consumed in the refinement process. These facilities are powered by an onsite 175-megawatt coal-fired power plant, which itself consumes more than 37,000 litres per minute. Every day, crews pull 150,000 tonnes of ore from the ground and process it down to just 820 tonnes of copper -- barely 1/500th of the total.
In short, Bingham is quickly reaching its productive limits. The latest round of expansion in 2012 required blowing out a wall of overburden -- worthless rock -- a 1.6km wide, 300m thick, and 1000m tall. Sure, doing so will expose more of the valuable ore, but it's going to take seven years and $US660 million worth of digging to get to it. “Literally and figuratively, we’ve got a whole mountain to move,” Barry Gass, former project director of underground development at Bingham told Pacific Standard. “At some point, the dollars and cents of that don’t make sense.”
And then there's the tailings. These are the leftovers of the copper extraction process, a toxic slurry of chemicals -- sulfuric acid, arsenic, lead and cadmium to name a few -- and powered gangue particles the size of a grain of sand down to a few micrometres. This stuff is nearly as bad a nuclear waste, remaining deadly for thousands of years. What's more, it's not like you can just switch to a different extraction method to eliminate it. This stuff is not a byproduct, it's present in the ore itself and you can't get the copper without making it. In Bingham, the other 149,000 tonnes of rock pulled out every day that aren't copper are, you guessed it, tailings.
What's more, the liberation of copper from the gangue also tends to free sulfides. These ores were formed deep within the Earth but, under aerobic surface conditions, rapidly oxidize to produce sulfate and acids. These then mix with atmospheric moisture to form Metalliferous Drainage -- not unlike acid rain runoff -- which cannot be readily reabsorbed by the local environment. While mining operations in the developed world have strict limitations on where and how these tailings are dealt with in an environmentally responsible way, the same cannot be said for many such operations in developing nations. But at the current going rate of $US3 per pound (up from less than a dollar at the start of the decade) the threat of ecological destruction seems a small price to pay.
The price of copper had been stagnant since the early 1980s when the US and Europe began moving away from the industries that Asia was killing them in -- automotive production for instance -- and more towards a service-based economy. This was before China really awoke as a modern industrial powerhouse and demand for the ore, therefore, remained stable for years. In 2000, you could buy a pound of copper for just 78 cents. As Tim Heffernan of the Pacific Standard explains,
Closure of the [Bingham] pit was slated for 2013. It would be the end of an era.
That end did not come. If you visit Bingham Canyon today, you’ll find a fleet of house-size dump trucks descending into the pit, loading up on rock, and climbing back up and out, around the clock. The pit is being widened and deepened to expose new ore, even as current mining operations continue.
Rio Tinto is planning to build a second mine on -- or rather, under -- the site. The aboveground operation will now be shut down around 2029. But Bingham Canyon is likely to go on. According to the current plan, the giant pit will give way to a giant underground mine, already in the early stages of construction, 2,000 feet beneath the pit’s floor.
The plan calls for five blocks of ore, each more than half a mile square and a third of a mile tall, to be carved out of the solid rock underneath the pit. In theory, the void created could swallow midtown Manhattan from 33rd Street to 57th Street; 500 feet of empty air would hang above the spire of the Empire State Building. The project would completely transform the mine’s operations. Ore from an open pit is dug from above, like sugar spooned from a bowl. Ore from an underground mine is dug from below, like sugar spooned out from the bottom of a pile, except that the sugar is a city-size slab of solid rock.
Why would a mining operation on the edge of insolvency, facing eve-increasing production costs even bother expanding? Because China. In the early 2000s, China's economy exploded, a middle class emerged and with it, all the desires for a well-appointed household with modern conveniences. Conveniences that demand copper. China's demand for copper tripled nearly overnight and the country now consumes 7.9 billion tonnes of it annually, the most in the world. The price of copper jumped nearly 200 per cent in less than a decade thanks to that explosive demand growth, from 78 cents in 2002 to a peak of $US5 in 2007 just before the Great Recession bitch-slapped the world economy and pushed the price of copper down to its current level floating around $US3.
Industry analysts expect the price to stay around that level for the next two decades so don't expect meth heads to stop stealing every piece of copper that's not nailed down any time soon. [Pacific Standard, Wikipedia, Wikipedia, Wikipedia, 4 - Resolution Copper]
Top picture: Axel Seidemann/AP, Ross D. Franklin/AP, Denr Ho/AP, Rick Bowmer/AP