Preface. Economists don’t believe in “Limits to Growth”, but good grief, if sand can grow scarce for fracking of oil and gas, and everything else for that matter (see more peak sand posts here), then surely other important stuff has limits too, such as uranium, lithium, fresh water, rare earth metals, and more.
Alice Friedemann www.energyskeptic.com author of “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer, Barriers to Making Algal Biofuels, and “Crunch! Whole Grain Artisan Chips and Crackers”. Podcasts: Collapse Chronicles, Derrick Jensen, Practical Prepping, KunstlerCast 253, KunstlerCast278, Peak Prosperity , XX2 report
Vince Beiser. 2018. The World in a Grain. The Story of Sand and How It Transformed Civilization. Riverhead Books.
The fracking boom in the United States has created a voracious hunger for
what’s known as “frac sand. It happens that there are huge deposits of just
that kind of sand in Minnesota and Wisconsin. Result: the fracking rush in
North Dakota has sparked a frac sand rush in the Upper Midwest. Thousands of acres of fields and forests have been stripped away so that miners can get their hands on those rare grains.
Thanks to the fracking boom, which kicked into high gear in 2008, the United States has overtaken Saudi Arabia and Russia to become the world’s biggest oil and gas producer. None of this could happen without sand. America’s fracking fields are the latest front to which we have deployed armies of sand to maintain our lifestyle.
By shooting a highly pressurized mix of water, chemicals, and sand into a well bore, drillers shatter the surrounding shale, spider-webbing it with tiny cracks through which the hydrocarbons can flow. They need the sand to keep the cracks open, holding fast against the pressure of the surrounding rock that wants to close them back up.
Every one of those wells needs sand, and lots of it. A single well can use as much as 25,000 tons—enough to fill more than two hundred railroad cars. But like members of a specialized combat unit, frac sand grains need to meet a list of highly specific physical requirements. They must be hard enough to withstand all that pressure, which means they must be at least 95 percent quartz.4 That eliminates most common construction sand, shrinking the pool to the silica sands used for glassmaking. But frac sand must also have the right shape: small enough to fit snugly into the frack cracks and rounded enough to let the hydrocarbons slide easily around them.
Most quartz grains, you’ll recall, are angular; there aren’t many places where you can find grains with such high purity and low angularity. The quartz sands under the ground of western and central Wisconsin have just that rare combination. These are ancient grains that were eroded, transported, then buried and uplifted again. Generally speaking, the older a grain is, the more rounded it is, thanks to however many extra million years of having its angles and edges worn down. Wisconsin also happens to have an excellent rail network and relatively lax environmental regulations. And so the fracking boom has sparked a frac-sand boom in the Badger State. Thousands of acres of the state’s farmland and forest are being torn up to get at the precious silica below.
In 2010, there were ten frac sand mines and processing plants in Wisconsin; four years later, that number had shot up to 135.6 The state produced around 25 million tons of frac sand in 2014, worth nearly $2 billion.
Production is likely to continue growing, since oil and gas operators have learned that increasing the amount of sand they shoot into a well increases the yield of oil or gas. New frac sand mines are also being opened in Texas as producers seek sources closer to the oil fields.
Nationwide, the legions of silica sand used for fracking have grown tenfold since 2003.7 They now dwarf those used for glassmaking and all other purposes, including silicon chips. By 2016, total silica sand production stood at nearly 92 million tons per year, almost three-quarters of which was used for fracking. Only 7 percent went to the glass industry.
The first step, he explained, is for excavating machines to scrape off the “overburden”—the plants, trees, topsoil, and unwanted miscellaneous rock lying on top of the sandstone that is their target. One reason Wisconsin silica sand is so desirable is because it lies very close to the surface, requiring relatively little digging to get at it.10 The topsoil is piled somewhere out of the way; it will be needed to help reclaim the land once the mine is tapped out, as required by law.
Once the sandstone is exposed, blasting experts drill a grid of holes into it, pack them with explosives, and simply blow a chunk of the hillside to smithereens. The sandstone shatters and collapses in a heap of . . . well, sand and stones. Front-end loaders dump the raw sand into trucks. After the “raw pile” is cleared away, excavators tear off another swatch of overburden and the process starts again, the hill disappearing slice by slice.
Down on the mine floor, the trucks haul the sand a few hundred yards to another pile, from where it’s fed into a complicated behemoth of a machine, a forty-foot-high Frankenstein of pipes, tanks, ladders, catwalks, and conveyor belts. A series of belts haul the sand up some thirty feet to a sorting screen, where jets spray it with water to turn it into a slurry. This sand-water mixture is then pumped onto a series of vibrating metal screens, which separate out first the miscellaneous rocks, then the oversize grains, shuffling these unwanted bits into a waste pile. Once everything bigger than .8 millimeters has been screened out, the remaining slurry is pumped up through corrugated pipe into a kind of upside-down pyramid called a hydrosizer. One hundred jets blast down into the cone, creating a carefully calibrated rising current that carries the lighter grains up and over the top into a trough, while the heavier ones sink to the bottom. By controlling the strength of the jets, you control the size of the grains that sink.
That sand is then run through a series of four attrition tanks—basically giant washing machines that spin the slurry, making the grains grind against one another, washing off silt or other impurities that might coat them. Last stop is a dewatering screen, a mesh of tiny slots measuring .01 millimeters, big enough for water to get through but not sand.
The sand is taken next to the drying plant, a vast warehouse-style building a few hundred yards away. Trucks load the washed sand into a metal hopper that feeds it onto another series of rising conveyor belts that carry it up to a doorway in the dryer plant, some twenty feet above the ground. Inside is a cavernous space, untouched by natural light, filled with another set of machines. The sand gets one more sifting, to filter out any stray rocks that might have gotten in on the journey from the pile, and then is fed through a long cylindrical tank.
A series of ducts underneath the tank blows hot air upward, drying the sand, while smokestack-like chimneys whisk away stray silica dust. “That’s the bad shit,” says Losinski. “That’s the stuff you don’t want to breathe.” Crystalline silica dust is sharp and jagged, especially when it’s freshly formed—like that found at sand mines and processing sites—and it can wreak havoc on the lungs. It’s been known for decades that too much exposure can cause silicosis, an especially severe lung disease.
A final relay of vibrating screens separates the sand into three size grades. Those are then hauled up a hundred feet in bucket elevators, vertical conveyor belts fitted with dozens of fiberglass buckets, and dumped into one of the 3,000-ton silos atop which Losinski and I stood. Trucks drive right up to the silos, fill up, and haul the product to the nearest rail station in Winona, Minnesota. From there, it’s off to the fracking fields.
There are a number of potentially serious risks to be concerned about. The first is water. The mines need lots of it to create their slurry and to wash the sand; a single mine can run through as much as 2 million gallons per day. The miners get a lot of it from high-capacity wells, which pump more than 70 gallons a minute from underground aquifers. “There’s a lot of concern about whether that will affect groundwater and trout streams fed by these headwaters
There’s also the question of what to do with wastewater that has been used to wash and process the sand. Typically the wastewater gets pumped into settling ponds; this is where the flocculants Pat Popple worries about are added in. Flocculants help remove particles suspended in the water, which is good. But they also contain acrylamide, a neurotoxin and carcinogen, which is bad.
That compound could potentially leach from the ponds into groundwater or surface water, warns a 2014 report