Reporter's Notebook: Buried Treasure


If you just can't get enough of the Iron Range, read on for these two web-only nuggets. First: more history! Also, a detailed accounting of the cutting-edge science behind refining sulfide metals. Without further ado:

(Photo of the Rust Hull Mahoning mine, the largest open pit iron mine in the world. For a sense of scale, see the truck on the right side of the picture? And those two grey rectangles a little to the left of it? Those little grey dots are 12-passenger vans.)

It is said there are two histories of the Iron Range—one of the companies and the other of the workers. In the early days, the miners were European immigrants who came to the Range by the thousands. As Marvin Lamppa relates in his seminal history of the region, Minnesota’s Iron Country: Rich Ore, Rich Lives, “Their purposes for coming were clear. ‘You can get rich in America.’ ‘There’s work for everybody in America.’ ‘The streets are paved with gold in America.’”

Finns, Czechs, Slovenes, Italians, and others arrived in Duluth, quickly filtering up north to the small towns, sometimes no more than a collection of thrown-together bunkhouses at the edge of a mine. The new arrivals were mostly men, but not exclusively; some brought families, and some women made the trip alone to work in boardinghouses and restaurants.

Pay for the miners was a fraction of city salaries. And while the work varied by mine, and mostly by whether it was under or above ground, there was this much in common, according to Lamppa: workers made between $12.50 and $20 a week, worked 10 hour days, six days a week, and faced layoffs in winter.

And they were pushed hard to produce. Underground miners, for instance, worked on contract. Organized into small groups and assigned a section of the mine to hack away at with their pickaxes, they were required to fill a certain number of carloads of ore per day. Paid by the load, the men also faced losing their jobs if they couldn’t fill their quotas. More immigrants were following them, ever eager for work.


The mines were also fraught with danger. Many men were run over by ore cars, blown up by premature dynamite explosions, or crushed by the crumbling earthen walls of a pit. The lack of a common language didn’t help. Orders and warnings were often met with blank stares.

The most infamous accident occurred on a clear winter day in 1924. It was late in the afternoon at the Milford, a shallow underground mine on the Cuyuna Range. The day crew of 48 miners was a few minutes from the end of their shift, and 165 feet below the surface. All at once came a groaning sound accompanied by a strong breeze. The noise quickly grew louder. Then came the shouts: “Water!” The miners sprinted to the shaft—the only way out. The lift was at the surface. Fighting panic, the men instead climbed the ladder, one at a time. But the water was too fast. Flooding the mine within minutes, it continued up the shaft. The men, one after another, lost their grip. Seven made it safely to the ground. Forty-one others drowned. It would take a year to recover all the bodies.

Under such conditions, it is little wonder that conflicts between workers and management arose. And management took a hard line. The face of U.S. Steel in Minnesota was Henry Oliver. Owner of Oliver Mining Company, a U.S. Steel subsidiary, the industrialist was not known for his sympathy toward the plight of workers. Without the mines, he reasoned, miners had no jobs. Without jobs, they had nothing. The miners, Oliver felt, should be grateful to his company.

In early 1916—a year in which the Iron Range produced a record 46 million tons of iron ore—an Italian immigrant name Joe Greeni, working at the St. James underground mine in Aurora, got his monthly paycheck. According to legend, he opened it up, saw it was for only a couple dollars, and threw his shovel to the ground.

“That’s it!” he yelled. He told his coworkers that it was time to stand up for fair, hourly wages. His rage was contagious. Within two days, he’d convinced all the miners in Aurora to stop working. Emboldened, the strikers marched with their families for 75 miles, from town to town, spreading their message of revolt. By spring, over 10,000 and 20,000 mine workers—the entirety of the Oliver Company’s workforce— was on strike.

Oliver was not amused. He hired 1,000 armed mine guards, a move quickly copied by the smaller companies. But unlike a previous strike a few years before, he’d been unable to hire replacements to man the mines. The strike lasted for months, until workers, demoralized and facing a painful winter, caved in.

A couple months later, U.S. Steel unilaterally met some of the demands, offering 25 percent raises, and even helping foster civic life, from supporting youth hockey to staging plays. America was about to enter the Great War, and the company, poised to meet the demand from the U.S. military, didn’t want any slowdowns in production…

If you want to learn more about the history of the Range, I'd strongly encourage you to get yourself a copy of Lamppa's book, Rich Ore, Rich Lives.


Moving along, here's a blow-by-blow account of PolyMet's plans for extracting the metals from the sulfur bearing ore. The other companies mentioned in Buried Treasure plan to use similar technology:

We pick up after the rock's been extracted from the mine and crushed to the consistency of baking flour. The finely-ground rock is mixed into a liquid solution to which chloride salts are added. The mixture is poured into a mammoth vat--essentially an industrial-sized pressure cooker--and filled with air bubbles. The added oxygen causes the sulfur to oxidize and turn into sulfuric acid. This reaction gives off heat, which triggers further chemical reshuffling. First, the noble metals—gold, silver, and the various platinums—fuse with the chloride salts. With an adjustment to the solution’s pH level, these new salty metal molecules turn into a sludge and form at the top of the vat. The highly valuable slurry is scraped out, filtered, packed into bags, and shipped off to refineries all over the world to be turned into pure platinum, gold, and silver.

The remaining metals—copper, nickel, and cobalt—also undergo a chemical transformation triggered by the sulfur-driven heat. Instead of forming with the chlorides, though, they merge with the sulfuric acid. Another change in the solution’s pH allows these sulfide molecules to float to the top of the vat, where they are ladled out.

The solution’s next stop is a room full of boxy vats resembling bathtubs. The liquid is dumped into the tubs and electrically-charged sheets of titanium metal are dipped inside. The carefully calibrated charge attracts the copper molecules, causing them to jump from the liquid and form like frost on the plate. The plate is removed and the copper is scraped off. The copper, 99.99 percent pure, is now ready for sale.

This leaves just the nickel and the cobalt, which, after another change to the solution’s pH, form a powdery, light green substance that is separated from the liquid and, like the noble metals, dried and shipped elsewhere for final production.

As for the solution itself, it is cleared of the remaining waste minerals and sent back to start the cycle all over again. After awhile the solution becomes what chemists call “tired,” meaning that impurities have invaded, bonding with the acid and salt, and making it less effective. When this happens, the liquid is taken out of commission and mixed with limestone, which transforms it into a chalky substance called gypsum. If sufficiently pure, gypsum can be sold as wallboard. Otherwise, the relatively innocuous substance is dumped alongside the waste rock.