April 24, 2012
Student team’s project earns EPA accolades
CARBONDALE, Ill. -- An interdisciplinary team of students at Southern Illinois University Carbondale is among the winners of a government-sponsored competition aimed at finding better, more sustainable ways to promote quality of life for humans while protecting the environment.
The students, led by Manoj Mohanty, professor of mining and mineral resources engineering in the College of Engineering, was one of just 15 teams out of 45 proposals nationwide to advance to the second and final phase of the U.S. Environmental Protection Agency’s “P3” competition. The win, which was based on the team’s Phase I proposal, reports and presentation, as well as its Phase II proposal, made SIU Carbondale’s team the only one from Illinois to advance and put it in elite company with universities such as Princeton University and the University of California-Davis, Mohanty said.
The team also will receive $90,000 during an18-month period to implement its design, which is titled “Sustainable Utilization of Coal Combustion Byproducts through the Production of High Grade Minerals and Cement-less Green Concrete,” Mohanty said. Its goals are finding ways to extract and recycle metals from coal combustion byproducts such as ash that will reduce the need for mining and also lead to a concrete with reduced carbon dioxide emissions.
For the last eight years, the EPA has solicited applications for P3, which stands for people, prosperity and planet. The proposals are aimed at conducting research and developing and designing solutions for real life issues involving sustainability.
Mohanty, who advised the team of students along with Sanjeev Kumar, professor and distinguished teacher in the Department of Civil and Environmental Engineering, said the students’ project is aimed at mitigating the environmental issues associated with using coal for energy.
One of the biggest issues is disposing or mitigating the leftover ash when coal is burned. The SIU Carbondale team is trying to develop low-cost processes to extract from the ash various valuable minerals, such as iron oxides and titanium oxides, as well as using byproducts to manufacture so-called “cement-less” concrete that instead relies on polymerization for strength.
Coal combustion creates approximately 136 million tons of fly ash each year in the United States. Less than 45 percent of that is being mitigated through various processes and the rest is dumped as waste in ash ponds at power plants and landfills, Mohanty said.
The team currently is experimenting with fly ash from several different areas of Illinois, which they are feeding into a multi-stage pilot processing system aimed at extracting valuable substances, metal oxides and minerals, which can make up 10 to 20 percent of the ash material. Another, parallel path of the research involves using processed fly ash to create geopolymer concrete, which potentially has advantages over traditional concrete recipes.
Fly ash in its raw, unprocessed state is what is left over when coal is burned, such as in a power plant. The high temperatures present in such combustion create structures known as cenospheres, which can be highly useful as fillers in concrete and ceramics and certain paints and coatings. The fly ash also contains magnetite, a naturally magnetic mineral that is used in a variety of industrial and environmental applications, and other minerals and metal oxides.
The concept the team uses to separate these valuable substances from the fly ash tailings starts much the same as the process involved with the old gold miners’ panning method. The fly ash, along with water, is poured into the top of a water “cyclone,” consisting of a vertical, twisted water pipe that looks like a big corkscrew (or another, simpler structure that relies on water flow, as well). As the mixture swirls downward through the structure, gravity separates the heavier material from the lighter -- the magnetite and assorted other minerals and impurities from the lighter cenospheres.
With the cenospheres removed, the remaining fly ash then goes through a magnetic separation process that removes the magnetite. Finally, the team uses acids to leach valuable aluminum, titanium and iron from what remains.
Recovering the minerals helps the environment by cutting down on the amount of mining for them that must take place, Mohanty said. The process could eventually be applied to ash ponds that are rich in such minerals.
While commercializing such value-recovering efforts is one goal, the other involves creating cement-less, geopolymer-based concrete formulizations using fly ash.
The vast majority of concrete is formulated using the Portland method, which uses traditional cement. That method, while tried and true, also creates a substantial carbon footprint that might account for up to 8 percent of total CO2 emissions.
A geopolymer concrete, which uses heat to polymerize and harden the concrete instead of the CO2-producing action in traditional concrete, might cut down on those emissions substantially.
Hamid Akbari, an engineering science doctoral student in the Department of Mining and Mineral Resources Engineering in the College of Engineering, was the student leader of the team. Tom Heller, a senior in mechanical engineering, the spokesman. The team also included Sudha Bhusal, graduate student in civil and environmental engineering; Sanguok Shin, engineering science doctoral student in civil and environmental engineering; Nick Culberth, undergraduate student in mining and mineral resources engineering; Xinbo Yang, master’s student in mining and mineral resources engineering; Pravin Jha, engineering science doctoral student in civil and environmental engineering; Mohammad Rahman, doctoral student in geology; Baojie Zhang, former doctoral student; Prabir Kolay, assistant professor of civil and environmental engineering; Sue Rimmer, professor of geology and associate vice chancellor for research; and Tomasz Wiltowski, professor of mechanical engineering.
Mohanty said the winning teams were announced in no particular order, so hearing SIU Carbondale’s name announced late in the list was exciting.
“We were all ecstatic to hear the name of Southern Illinois University Carbondale being called after 13 other schools,” he said. “It was a very special moment for us.”
To learn more about the proposal, go to http://usepap3.siu.edu/.