#tailings

Donbas Tailings and Siverskyi Donets river

The summits of mine dumps may possess a conical shape and stand out as notable landscape features, but they can also be flat and eroded. A mine dump is formed from waste rock delivered from the mine or quarry to the apex of the cone by railcars, skip hoists, or conveyors.

One man’s trash is another man’s treasure

Spoil heaps may be considered uneconomic waste by many companies, but to geologists they are a treasure trove of sparkling minerals and criss crossing veins. My sixth form geology teacher would regularly raid a white gold spoil heap in Wales, giving specimens to her students as good luck charms for their exams. We still don’t know if her activities were entirely legal, but they did help spark a love of minerals within her students that lasts to this day.

However, these rocks aren’t just pretty to look at; they can also provide an insight into the type, age and order of mineralisation that occurred. So much information can be gathered from such sites that universities will take students to spoil heaps as a field based exercise in mineral exploration.

Of course they are also the perfect place to add to any rock hounds collection, after all one man’s trash is another man’s treasure!

- Watson

Morenci Mine

Dusted Series

Morenci, Arizona

Hasselblad 500c/m

*High or more severe hazard potential includes high, very high and extreme classifications, which denote a failure could cause the loss of up to 10 lives (high); the loss of up to 100 lives (very high); and the loss of more than 100 lives (extreme); plus varying levels of environmental damage.   †According to available data. Size of circles doesn't indicate volume of material being held by a dam. Sources: U.S. Army Corps of Engineers; mining companies

Excerpt from this Wall Street Journal story:

An earthen dam is set to rise behind the trees of Dan Ehman’s 120 woodland acres in northeastern Minnesota’s Iron Range, a region with close ties to mining for more than a century.

The planned dam, designed to hold back hundreds of millions of tons of mining waste, will be similar in structure and height—soaring 250 feet above Mr. Ehman’s century-old log cabin—to one in Brazil that burst in January, killing 270 in a tsunami of sludge.

That disaster, the deadliest of its type in half a century, has upended the global mining industry. The world’s biggest mining giants have spent months and millions of dollars re-evaluating their dams. Institutional investors are scrubbing their portfolios, looking for companies with risky structures—and helping to publicize potential stability issues. And environmentalists are getting new support from residents, some of whom are learning for the first time about the potential dangers of the dams in their communities.

The U.S. remains one of the countries where the type of dam used in the Brazil disaster, known as an upstream design, is still being built. They are effectively banned in parts of Canada, in many situations in the European Union and now, in Brazil itself. The planned dam outside of Embarrass uses the design. Last month a court suspended permits for the mine until the builder makes clear how it has assessed the Brazil disaster.

“We are allowing dams in the U.S. that countries in the developing world do not accept,” said Steve Emerman, the owner of Utah-based mining and groundwater consultants Malach Consulting.

In the Brazil disaster, a dam holding tons of iron ore tailings near the town of Brumadinho crumbled, sending water, rock and mud flooding over a square mile. Inspectors had worried about the dam’s integrity for months.

Upstream design dams are built up with the tailings in a stair-step fashion. The design is one of the simplest and least expensive. Critics say it is also one of the most dangerous. The U.S., unlike some other mining nations, doesn’t have an accessible database of upstream dams, though experts estimate there are more than 500.