UK researchers tackle ultra-clean coal

A NEW chemical process for removing unwanted minerals from coal could lead to greater reductions in carbon dioxide emissions from coal-fired power stations, by using chemical recycling to make coal cleaning processes more cost-effective, according to British researchers.
UK researchers tackle ultra-clean coal UK researchers tackle ultra-clean coal UK researchers tackle ultra-clean coal UK researchers tackle ultra-clean coal UK researchers tackle ultra-clean coal

The research team is based at the University of Nottingham and funded by the Engineering and Physical Sciences Research Council.

Although clean coal technologies already exist, such as the conversion of coal to gas to drive power generation turbines, the researchers say that the costs associated with removing unwanted minerals from coal has inhibited the adoption of clean coal technologies.

The new approach involves using chemicals to dissolve unwanted minerals in the coal and then regenerating the chemicals again for re-use, thus avoiding the costs of using fresh chemicals each time and of chemical disposal, which can also have an environmental impact.

By removing unwanted minerals before the coal enters the power plant the new process also helps protect the turbines from corrosive particles.

The aim is to cut unwanted minerals in coal from around 10% to below 0.05%, making the coal "ultra clean".

The team is using specific chemicals to react with the minerals to form soluble products that can be separated from the coal by filtration in a leaching process.

Hydrofluoric acid is the main chemical being tested.

The UK researchers claim chemical recycling has been largely ignored in other forms of clean coal research, despite the inherent cost benefits.

Dr Karen Steel of the School of Chemical, Environmental and Mining Engineering is leading the project.

"A lot of research took place in the 1970s and 1980s to see if coal cleaning was viable," she said.

"The conclusion was that it was too expensive. With the environment high on the global agenda and coal certain to remain a key energy source for decades, it makes sense to see if the perception is still justified today."

If the process proves to be both technically viable and economically competitive, the researchers hope the new process will ensure that world coal reserves are harnessed with less impact on climate change.

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