Under Ground

Under Ground

    Out of sight, out of mind, or so the saying goes.  But it could equally apply to the world of mining for we seem to have a fascination with what's below us.  Everything from hidden tunnels to caves to deep mines seem to captivate us with their darkness and recesses and perhaps, yet-to-be discovered buried treasures.  But just as with sand castles, mining is actually quite the dangerous occupation, the recent movie of the Chilean miners being rescued (the Hollywood version is titled The 33 for the number of trapped and rescued miners back in 2010) puts the number of mining deaths at 12,000 per year, a number which is disputed but is also possible due to the number of unregulated mines in many oppressive countries.  And mining is everywhere, as witnessed by the mining disaster less than a week ago in Myranmar which left 13 dead.  Turkey, South Africa, China (said the BBC just after the Chilean disaster: China has the world's largest mining industry, producing up to three billion tonnes of coal each year.  But while the country accounts for 40% of global coal output, it is responsible for 80% of mining deaths around the world each year.) and now Mongolia where Rio Tinto will expand its massive Oyu Tolgoi copper/gold mine, a mine that will have 125 miles (200 km) of tunnels and dig deeper than the height of three Empire State buildings.  Of course the U.S. isn't immune from all of this, even though mining deaths have been reduced substantially over the past few decades.  In an article from the conservative American Enterprise Institute it said: To understand how dangerous coal mining in the US used to be, consider that there were more than 1,000 US coal mining deaths in every year between 1900 and 1945 and more than 90,000 total coal-related deaths during that period, more than 2,000 deaths in the 24 years between 1905 and 1930, and more than 3,000 deaths in the year 1907.   As of last year, that reported number had dropped to 28 in the U.S.  Diamonds, gold, copper, even Poldark...our lust for going underground seems almost too tempting to pass up.

    Little of this would have really interested me had I not stumbled upon an article about another Rio Tinto copper mine, this one located in Arizona (remember Arizona from a post not long ago...yes, the one on mining for uranium ).  The piece from Bloomberg Businessweek gave a peek into what a mine deep in the earth really entails, and it was far from what I expected: Visited on a chilly day in December, the area around the top of the mine, the “collar” in mining terms, doesn’t look inviting.  Steam clouds pour from the mouth of No. 9.  It’s the hot air being drawn from the cave dug at the bottom of No. 10.  That far down, rocks formed billions of years ago still carry heat from the molten core of the earth.  Without the elaborate refrigeration system that pumps chilled air down No. 10, the bottom of the mine would be 180F, far too hot for a human to withstand.  “You’d cook,” says Randy Seppala, 60, project manager for shaft development.  Miners have long called this heat the “hand of the devil,” reaching up from the depths...After eight minutes a low roar from below picks up.  By now, about 4,600 feet from the surface, and 400 feet below sea level, the air pumped down by the refrigeration system has lost its chill.  At this depth, Resolution (the mining company) has built a second cooling station, dug laterally off the mine shaft.  Here, the air gets circulated through a second set of giant cooling coils, built into the rock and encased in metal.  Two fans, 5 feet wide, blow the freshly chilled air back to the bottom of the mine.  A giant duct carries it the remaining 2,300 feet down.

    There was more to the story to pull you into the mine's depths: Before going down the No. 10 shaft, visitors learn how to put on an emergency breathing kit consisting of a nose clip, breathing tube, and small oxygen bag you attach to your belt.  As the safety video points out, a fire or explosion can occur at any time in an underground mine.  Your ability to survive depends on being prepared.  There are lots of ways to die in a mine.  Roughly in order of likelihood, the most common include getting struck by objects falling down the shaft, falling down the shaft yourself, and being killed by an explosion.  In the last case, it’s probably not the fire that kills you, or even the force of the blast.  It’s the toxic gases that get released, particularly the high concentrations of carbon monoxide.  According to Andy Bravence, Resolution’s mine superintendent and Seppala’s No. 2, the breathing kit can get used up in a few breaths if you’re hyperventilating.  Dangerous levels of carbon monoxide are in the range of 3,500 parts per million.  “One breath of that, and pretty much she’s gonna collect your insurance,” Bravence says.  “It sucks all the oxygen out of the blood and knocks you out.  Your next breath you won’t remember taking, and you’re pretty much done after that.  But you know: Don’t worry.”

    It's an interesting peek into the world of the miner, and likely something miners in less-developed countries (with less safety rules and features) are even informed about (imagine their glimpse of natural light fading ever so quickly as they descend into the mine, their lungs dealing with dust and poorly ventilated air, breathing in what canaries-in-the-mine once breathed, then working in cramped quarters chipping rocks often filled with what could become toxic materials if mixed with water, a more detailed explanation of these materials as they come up from the mine was expressed in Wikipedia: Ore mills generate large amounts of waste, called tailings. For example, 99 tons of waste are generated per ton of copper, with even higher ratios in gold mining - because only 5.3 g of gold is extracted per ton of ore, a ton of gold produces 200,000 tons of tailings. These tailings can be toxic. Tailings, which are usually produced as a slurry, are most commonly dumped into ponds made from naturally existing valleys. These ponds are secured by impoundments (dams or embankment dams). In 2000 it was estimated that 3,500 tailings impoundments existed, and that every year, 2 to 5 major failures and 35 minor failures occurred; for example, in the Marcopper mining disaster at least 2 million tons of tailings were released into a local river. Subaqueous tailings disposal is another option. The mining industry has argued that submarine tailings disposal (STD), which disposes of tailings in the sea, is ideal because it avoids the risks of tailings ponds; although the practice is illegal in the United States and Canada, it is used in the developing world.


    This isn't meant to paint a blighted picture on the entire mining industry; indeed, many mining companies have to jump through so many environmental hoops that it factors into their decision as to whether a mine will prove profitable or not.  But anytime you dig that much dirt and rock out from the ground, it has to go somewhere (and the ground underneath will likely begin to sink...in the Arizona mine discussed in the article above, a crater estimated to be 2 miles across will become visible above the mine).  There are worse options such as stripping the top "layer" off and grabbing what you can when you reach the ore (says Wikipedia, this accounts for 85% of the mining methods in the U.S.).  Often, land is also traded since areas nearby the mine have to be cleared.  But imagine yourself a young person with healthy lungs and needing a good steady job.  In mining country, the mines proved attractive.  So down, down, down you would go, ready to risk the possibility of the mine collapsing or the ventilation stopping or the heat overtaxing the cooling system.  This is still around today, sometimes with safety features and sometimes with just a few propped up timbers.  Workers are many, jobs are few.  In the Chilean incident, a rock trapped the miners, a rock twice as hard as granite and twice as large as the mass of the Empire State building...one rock.  Mining is not easy work by any means, and certainly not risk-free.  The article in Bloomberg Businessweek is worth reading...you just never know when you might bump into a miner.