Advancing Cleaner Coke Production

By Laura Nichol
June 2012

Researchers are designing a pilot-scale Energy Recovery Coke Oven to advance cleaner coke production and promote Canadian metallurgical coals.

CanmetENERGY technologists collecting coke into a quench cart from a pilot-scale oven

As the world searches for ways to reduce the use of fossil fuels, much steel and iron production remains reliant on a familiar energy source: metallurgical coal.

Metallurgical coal blends are made of coals with unique properties: When carbonized in a coking oven, they become a high-carbon content material called coke. Widely used in iron and steel production, coke plays key chemical and physical roles in the conversion of iron ore to iron metal.

Typically, coke is produced in slot-type ovens. But around the world, Energy Recovery Coke Ovens (ERCOs) are becoming more prevalent in iron and steel plants because they leak fewer pollutants and can lead to reduced greenhouse gas emissions.

To further advance ERCO technology, researchers at Natural Resources Canada (NRCan) have teamed up with members of the Canadian Carbonisation Research Association. Together, they are designing, building and testing Canada’s first ERCO at the CanmetENERGY research facility in Ottawa. Researchers aim to further increase the productivity, marketability and environmental benefits of ERCOs.

Reduced Leakage of Harmful Pollutants

Crushed coals are fed into the coking oven to create coke

Kirby Wittich, an NRCan research engineer working on the oven’s design, explains the main technical advantage of ERCOs. “They [ERCOs] operate at a slightly negative pressure,” says Kirby. “This prevents most leakage from the doors, charge ports and brick refractory during the coking process. As a result, ERCOs release only a fraction of the harmful pollutants leaked by slot-type ovens, such as volatile organic compounds, sulphur dioxide, nitrogen dioxide and carbon monoxide.”

More Renewable Carbon, Less Greenhouse Gases

The other environmental advantage of ERCOs is that they better tolerate the replacement of coal with biomass in coke blends. In this process, some of the non-renewable fossil carbon is replaced with renewable carbon from forest materials. The forest material is charred and compressed through briquetting, then blended into metallurgical coal mixes.

Biomass material is considered carbon-neutral because the carbon released through combustion is re-absorbed by growing trees. Its use in metallurgical coal blends could have significant benefits for the climate. “In the near to medium term, a 15 percent reduction in the amount of greenhouse gases produced during coke consumption is foreseeable,” says Kirby.

Kirby’s team will investigate how much biomass can be included in coal blends while still maintaining the coke quality necessary for blast furnace operation.

Encouraging Investment & Marketing Canadian Coals

Coke chunks are fed into the blast furnace during the production of iron and steel

Researchers will also create detailed data sets on the coke quality produced by the ERCO. Not currently available for coke makers and metallurgical coal producers in North America, this data will help validate the viability of ERCOs. Proven viability will reduce the investment risks of building commercial-scale ovens and accelerate adoption by industry.

The research will also benefit Canadian coal companies. “Western Canadian coals will be tested in the pilot-scale oven because of their unique properties,” says Kirby. “They not only work particularly well when blended with charred biomass, but they also improve the performance of cheaper, lower-grade coals. Proving their effectiveness in ERCOs is likely to increase their market value, especially given increasing ERCO demand.”

Overall, the development of Canada’s first pilot-scale ERCO aims to advance cleaner coke production that releases fewer pollutants and leads to fewer greenhouse gas emissions. At the same time, the research provides a new opportunity for the Canadian coal industry to market Canadian metallurgical coals.

For more information about NRCan’s research on cleaner fossil fuels, visit the department’s “Clean Fossil Fuels” web page.

To read about related articles, see Clean Energy.

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