The mine can produce 4 million tons of rock salt each year, but because of mild winters, the last two years the mine has produced about 75 percent of an average year. Last year, five Ohio counties produced about 4.5 million tons of salt. (Ohio is the fifth biggest producer of rock salt in the country.) The Cleveland mine produced the most.
How much longer will the mine exist?
Every year, engineers revise a 25-year plan, deciding where to drill next.
The mine could conceivably go on forever, expanding to the Canadian border, at least. But site manager Steve Horne says it has at least 50 years more, until global warming reduces the need for road salt or the process of trucking employees out to and salt back from the far reaches of the mine becomes too expensive.
How long has the mine been here?
Since about 1958, a year after the Morton salt mine in Grand River, under Lake Erie in Lake County. Cargill Deicing Technology bought the Cleveland mine in 1997.
Why is the mine under Lake Erie?
The mine could be anywhere in the Great Eastern Salt Basin, under a huge area stretching from Michigan to New York, through Ontario. Under Lake Erie, though, Cargill has to lease land from only one owner – the state of Ohio. Plus, Cargill can ship the salt all over the Great Lakes.
Does the mine leak?
Yes, in two spots: the skip (a cage elevator) and in one room where the ceiling converged and caused the mine to close temporarily four years ago. The water comes from the layers of rock in between Lake Erie and the mine, not from the lake itself, Horne said.
Cargill is still managing the leaks. Overall, the air in the mine is dry, though it may get humid in the summer.
“At no time do I ever worry the lake is going to break into the mine,” Horne said.
Is it cold?
Not really. The temperature is pretty steady year-round, about 68 degrees.
Does it smell?
Just a little stale and dusty, which sticks to your clothes and your hair. A single fan pushes fresh air through the mine and channels the dusty air, polluted with diesel fumes, back up to the surface. The fan is so strong that near the entrance, wind blows your hair around.
How far does the salt go from Cleveland?
From Cleveland, ships carry 1.6 million tons of salt to ports around the Great Lakes, including Duluth, Minnesota; Chicago; Milwaukee; and Canada. Salt is also transported by train as far as Massachusetts and by truck to southern Ohio. Governments buy it to spread on the road to melt snow and ice; businesses buy it for parking lots and other surfaces.
Cargill has two other rock salt mines, in New York and Louisiana.
Morton has a mine in Fairport Harbor, also under Lake Erie.
How many employees work at the mine?
About 220, with 160 of them below ground. Employees use a plastic, white and green tag system, to show who is underground at any time. They generally work 8-hour shifts around the clock, five days a week. On weekends, crews do maintenance.
How do they get the salt out?
Workers drill holes in the salt walls, then insert ammonium nitrate fuel oil. They blast the wall, then use a modified front-end loader called an LHD (short for load, haul, dump) to deposit the chunks of salt in a crusher-feeder-breaker machine, which channels it onto a conveyer belt. The belt leads to the mill, where the salt is refined, before being hoisted out on another skip. A giant machine claws at the ceiling and walls, to get all the excess salt.
About 30-50 percent of the total salt is extracted, with walls and columns of salt left to support the structure. There are no other supports, aside from metal studs drilled into some portions of the roof.
What if something goes wrong?
Cargill has a detailed safety plan, and visitors have to watch a 21-minute safety video before venturing underground. Everyone underground must wear what’s called a self rescuer in a metal container on a belt. The device fits over your mouth and changes carbon monoxide into carbon dioxide. In an emergency, miners would exchange their self-resuers for larger self-contained self-rescue devices, kept in boxes throughout the mine. Those provide oxygen for an hour.
There are green reflectors lining the tunnels, showing the way out. And the mine has two safe rooms stocked with food, water and oxygen to last three days.
Can you eat the salt?
Not really, even though it’s about 98-percent sodium chloride. The salt is good enough for animal feed. But for table salt, that happens at separate mines, where companies generally extract brine through a well or capture ocean water. Then they evaporate the water.
Can anyone tour the mine?
No, it’s closed to the public. But to feel what it’s like underground, check out John Pana’s video at RocktheLake.com.
When it collapses, Lake Erie and other Great Lakes will be severely impacted.
Looks like they can still dig for a while ...
Interesting story, thanks
Cargill? Isn’t that now another fine Chinese company?
Awesome read! Thanks for posting!
My home town of Cleveland. I learned about this at 12 or so from the Cleveland Press
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The history of salt. it was not always a commoditiy.
There’s a defunct mine underneath Detroit. I’ve read that most of the equipment down there is from the 1940’s. Pristine vehicles that are completely encrusted in salt. They had to be disassembled up top and transported in pieces down an elevator to be reassembled in the mine.
If they ever came into the atmosphere, they would rust almost immediately.
First thing that struck me was, “this is a ginormous sinkhole just waiting to happen.”
Cool info. Looks like we’ll never run out of the most valuable thing since water. Thanks
I hear the guys that work there are the salt of the earth.
Salty air is very healthy for the lungs.
There are even underground hospitals in old salt mines.
Working salt mines is a great job.
There’s a salt mine under Detroit too.....
I had no idea fresh water lakes hid massive amounts of salt.
Thank you!
T post. I was down in the one under Detroit when I was young. My dad’s brother (RIP both) worked in the mine. The shaft was nearing Oakwood St. on the left while traveling northbound on Ft. Street. I remember huge trucks moving about. Another world underground.
Fascinating. Thanks for posting.