For This Engineer, Acid Mine Drainage Paints Quite a Picture

January 2, 2014"Painting With Acid Mine Drainage," a post on (the website of the American Society of Mechanical Engineers), details the unusual collaboration between two professors at the Ohio University in Athens (OUA), located deep in the state's Southeastern coal country.

Coal's storied history in Appalachia includes the abandoned mines that dot the region, typically leaching brightly colored runoff saturated with pollutants such as heavy metals into the watershed.
Guy Riefler, associate engineering professor at OUA, was touring the region in 2006 shortly after taking his post when he met someone "mining" iron sludge deposits from runoff sites. After separating out the metals, this individual was selling the pigments to paint companies.
Riefler's thought was, "If he was collecting deposits from sites, why not treat at the source?" Thus began a commercial venture to reclaim the metals to make paint pigment from the complex brew of heavy metals contained in acid mine waste.
Riefler enlisted students to draw samples, neutralize the water by adding a base to adjust the ph, and then oxidize the water as the ferrous iron converts to ferric iron and precipitates out.
Turning the resultant iron into a high-quality pigment base proved to be more difficult, however. "Iron can form a variety of different solids," says Riefler. "It has to be high in iron content and with a uniform crystal structure. We were producing a dry oxide but had a difficult time assessing things [such as color ranges] in my lab. Producing paint is an art and having an artist’s eye really helps."
Enter John Sabraw, an associate art professor on campus in Athens, who has had experience in preparing pigments. "The color can be affected by how high the heat is used to treat [the pigment]," Sabraw says. "With this material, you should be able to get a range from yellow to red to black. You have to learn how to tweak it through trial and testing."
A painting series called "Chroma" was the result of work over a two-year period between the two professors. But one question remained: How to make the venture profitable?

Riefler sees the concept scaling commercially, noting that the U.S. market for iron oxide pigment is roughly 230,000 tonnes per year, with some 178,000 tonnes imported, mostly from China.
The seep they've focused on has discharges of one million gallons per day of polluted water, with a possible yield of 2,000 pounds of iron per day. The plan calls for construction of a water treatment plant at the source of the seep to settle out the heavy metals, along with a sludge-processing system, both common technologies. Dewatering, and pulverizing the product to be of a suitable market quality, are still part of the process that needs some finessing.
Although the focus is on sustainability, after running the numbers Riefler sees the process as profitable. His work with Sabraw has drawn the attention of the U.S. Forest Service, which has been tasked to deal with acid mine drainage in nearby Anthony Wayne National Forest. The blog post notes that the university and the forest service have funded much of Riefler’s work so far, but that he’s looking for more funding to take the project to the next level.

Read the full post here

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