Coal offers great economic potential beyond its use as an energy source according to a researcher working to build a better picture of the elements within product coal and its waste stream.
Brisbane-based CSIRO research scientist Jane Hodgkinson has spent the past year looking at applications beyond burning coal for electricity or steel-making.
“We don’t yet have a well-developed mindset of seeing it as anything other than coal and leftovers,” she said.
Yet coal deposits can be associated with valuable metals and elements including lithium, gold and rare earth elements, while there is also work under way to use it for hi-tech materials such a carbon fibre and chips for electronic devices. Even brown coal in Victoria is gaining a new lease of life through trials to produce hydrogen for export.
A geologist, Dr Hodgkinson said her work to date was based on interviews with other coal experts within CSIRO and a desktop study of global research on the subject.
She says, while some is already used in the construction industry, the ash that is left when coal is burned may in some cases become a more desired product in its own right rather than primarily a waste stream.
Coal deposits may offer multiple revenue streams
“There are minerals, metals and elements that have fallen into the organic debris while it (coal) was forming and others that were introduced later. It gets concentrated over time as the coal compresses,” she said.
“In some parts of the world they have found quite high concentrations of gold and in some places uranium that has washed through as a secondary deposit.
“The coal can contain rare earth elements, lithium, cadmium and aluminium. These are often bound up in clays and other material found with the coal and in some places, if they are found to be of high enough concentrations, it may be worth recovering them for making batteries and other technologies we need for a low-carbon economy, ironically.”
Technological developments and further research into the make-up of coal should contribute to more coal deposits offering multiple revenue streams in future and, in some cases, energy may not even be the primary reason for mining a seam, Dr Hodgkinson said.
Chemicals derived from coal by-products are already used in a vast range of goods as diverse as benzene, ammonia gas, perfume and food additives.
And in China, Honeywell’s Methanol-to-Olefins technology is being used to convert coal to chemicals and plastics on a large scale.
“We have been doing these things, with 98 per cent of coal use in the world being for thermal (power generation) or coking and 2 per cent for other purposes,” Dr Hodgkinson said.
“With those new plants in China and a few other things going on, the International Energy Agency has predicted that will become 4 per cent by 2021.”
There is also potential for a huge range of carbon-based products drawing on the superior strength of carbon fibre and graphene.
“Graphene is extremely strong – it can be as strong as steel even if it’s so thin you can see through it,” Dr Hodgkinson said.
She said coal also had applications in technology, with international researchers developing the potential for a thin film of coal to be used instead of a silicon wafer, for example.
Waste from burning coal has been used in construction materials for a long time, with its thermal and strengthening properties offering further opportunities in that sector as well.
Dr Hodgkinson is especially interested in the potential for in-depth analysis of Queensland’s coal waste streams to yield ways to turn tailings and unwanted by-products into valuable resources.
She hopes to assess a range of Queensland core samples in the next phase of her research and from there attract funding for a wider study.
“I would like to develop a map that shows what we are finding in our coal so we can look towards some sort of a catalogue of what’s in the accessible ground,” she said.
“If we can start assessing coal in a different way and start having a view of it as a valuable mineral resource beyond something that is predominantly burnt or used for steel making, then we might have a different type of industry.”