New technology improves Anglo's mine rehabilitation

© Rasica – za.fotolia.com

Known as fungcoal, a combination of the words 'fungi' and 'coal', the R17.5m project harnesses fungi and weathered coal, and is being undertaken in partnership with Rhodes University's Institute for Environmental Biotechnology.

The partnership began in 2004, when thermal coal sought ways of accelerating and improving the quality of rehabilitation at its opencast mines.

Humic and fulvic acids

"Research shows that certain fungi have the ability to break down and liquefy coal that has been exposed to the elements. When accompanied with other microorganisms, they create humic and fulvic acids, natural fertilisers that are regarded as the building blocks of soil fertility and plant life," says mine closure manager Henk Lodewijks.

Humic and fulvic acids have two important properties. Firstly, they promote soil microbe and plant growth, and secondly, they significantly alleviate the compaction of rehabilitated soil, one of the greatest rehabilitation challenges facing the industry.

"As discard coal is used as a medium on which certain grass species grow, we significantly reduce the need for topsoil, a scarce and costly resource," explains Lodewijks. "What nature does in 60 years we are trying to do over six months, or one growing season."

The technology has been trialed at four Anglo American coal mines and in certain applications, has shown extremely positive results, both on rehabilitated mining pits and coal discard facilities.

Importance of fungi and bacteria

"Our aim is to restore the ecology of land that has been disturbed. This process is underpinned by organisms that cannot be seen with the naked eye. All organisms act in concert and allow the environment to resurrect itself," says the university's Prof Keith Cowan, adding that the research team has been fortunate in discovering fungi and bacteria so important to the process in a relatively short space of time.

"What we are doing is finding a complete toolkit of organisms for land that has been disturbed to ensure that it can be returned to communities for economic activity almost immediately after mining."

The next steps will be to establish a thorough record of land rehabilitated with Fungcoal and to gain a greater understanding of the product's use in other applications and over a longer period of time. Engagement with regulators will take place as the project moves closer to the commercial phase.