The University of Queensland’s Sustainable Minerals Institute (SMI) researchers have developed a new technique for predicting the rate at which coal mine waste releases salt into the environment.
To gain an industry perspective on the research, SMI is seeking partners in Queensland’s coal industry to help trial the techniques.
Following a two-stage project supported by the Australian Coal Association Research Program, SMI’s Environmental Geochemistry Group believes new procedures to predict the rate at which salinity is generated and released from coal spoils will offer the coal industry new insights.
ACARP soil salinity research team member Karan Jain said in order to reach the coal seam at an open cut coal mine, miners excavate enormous quantities of overburden material which is then dumped inside or outside of pit areas in the form of spoil piles.
“The problem is that when this freshly excavated material is dumped in the form of piles, it starts to weather as soon as it interacts with atmospheric conditions such as rainfall and oxygen,” Jain said.
“One of the issues associated with this weathering is the generation and release of salinity in terms of leachates or seepages.”
Spoils are waste rocks produced by open-cut coal mining operations which consists of rock formations and soil interbedded with coal seams. Spoils typically feature a high density of salt which is environmentally damaging if released in high concentrations.
Environmental Geochemistry Group leader associate professor Mansour Edraki said the new modelling would ensure mining companies have a better understanding of their spoils.
“Dissolution of salts in rainfall and their subsequent transport into waterways can adversely affect water quality, potentially for decades following the cessation of mining,” Edraki said.
“The current modelling that informs closure and rehabilitation planning for spoil piles and voids, provides mine operators with uncertain information and may be overly conservative and expensive.
“The methodology we have developed with the support of ACARP will equip them with more reliable, evidence-based predictions for the salinity loads of their spoil piles.
“While we have tested the modelling on spoils in natural conditions, we are now at the point where we want to advance to field trials, where conditions like water chemistry and volume are different.
“Queensland has a world-leading approach to rehabilitation, and we are keen to collaborate with the state’s coal mining industry to advance techniques and knowledge around the rehabilitation and closure of spoils and final voids.”