Associate Professor Karen Steel

Biography:

1992 - 1995. B.E. (Hons), Bachelor of Engineering (Chemical). The University of Melbourne.

1996 - 1999. Ph.D. (Engineering), Department of Chemical Engineering, The University of Melbourne.

2000 - 2008. Research Fellow then Lecturer. Nottingham Fuel and Energy Centre, School of Chemical and Environmental Engineering, The University of Nottingham, UK.

2009 - 2018. Lecturer then Senior Lecturer, School of Chemical Engineering, The University of Queensland.

2019 - present. Associate Professor, School of Chemical Engineering, The University of Queensland.

My research interests are in energy and resources, including coal science, gas recovery, and sustainable mineral processing with a strong interest in developing new technologies to solve major issues. I develop new experimental/analytical capabilities and innovative approaches to provide new knowledge and novel insights that can help Australian industries maintain and extend their competitiveness in world markets. I also develop novel process schemes by manipulating solution equilibria and are currently focused on developing new mineral processes that include CO2 sequestration.

Main themes:

Metallurgical Coal Carbonisation and Biocoke Production

I have pioneered the use of high temperature oscillatory shear rheometry to characterise the microstructure of coal during pyrolysis/carbonisation as it transforms into coke (an essential porous carbon material used for steel-making). I obtained real mechanical properties of the plastic phase that forms and studied viscoelastic thresholds for bubble nucleation, growth and coalescence which enabled me to develop a hypothesis for a process problem known as high oven wall pressure. The knowledge base created from this research has paved the way for better models to predict oven wall pressure and elucidated clever ways to control pressure through blending.

This led to an ambitious new focus to develop a mechanistic model for coke strength that would reveal why some coals are not well predicted and how the value of a coal could be improved through blending. I combine rheometry and X-ray micro-CT analysis to reveal the physical mechanisms by which the pore structure of coke forms and how its features contribute to coke strength.

More recently, I have turned my attention to examining how coal can be replaced by biomass in steel production given that 7% of the world's CO2 emissions come from producing steel. This involves examining the pyrolysis behaviour of biomass and finding ways to replicate the mechanisms that give rise to strong coke. Initial work has involved sugar can bagasse, an agricultural waste, and therefore involves examining the behaviour of grasses.

Significance: Coal is the 2nd biggest export earner for Australia, whereby the majority is metallurgical (met) coal used to make coke, and Australia is currently the largest exporter of met coal in the world. My research is used to ensure Australia remains at the forefront by enabling better predictions on the behaviour of different coals and providing new opportunities for the marketing of Australian coals.

Main collaborators: ACARP, BHP, Anglo American, Rio Tinto, Peabody, Vale, The University of Newcastle (Aus), CSIRO, School of Earth Sciences (UQ).

Novel Technologies for Increasing Gas Recovery from Coal Seams and Predicting Gas Production Rates.

Methane is a 'cleaner' fuel than coal because it is hydrogen-rich and can be burned in high efficiency combined cycles. Coal deposits in eastern Australia have enormous amounts of adsorbed methane (known as coal seam gas or coalbed methane) which has given rise to a fast growing industry whereby the methane is extracted, liquefied (LNG), and exported overseas. Extraction depends on the permeability of the coal seam. The most commonly used technology for increasing permeability is hydraulic fracturing, which originates from the conventional oil/gas industry where sandstone is the usual source rock. The structural properties dictating permeability for coal is different, whereby coal is already highly cleated due to the shrinkage process that occurs during formation. Instead of creating a new fracture network, our research has shown that it is possible to increase gas productivity by working with the existing cleat network, enhancing flow by dissolving the minerals within the cleats and etching cleat surfaces.

I have developed new laboratory and analytical capabilities to study the chemical and physical effects caused during chemical injection, including X-ray micro-CT analysis combined with pore characterisation and flow simulation (using GEODICT) to explain the permeability changes observed in laboratory injection tests.

I have also recently developed a new tool that enables the cleats to be examined as methane is desorbed (using high pressure cells and X-ray CT analysis). We aim to relate our observations to the structural properties of the coal and provide industry with a new capability to predict gas production rates for a given well over its life. Approaches taken are also applicable to predicting flow and adsorption behaviour of CO2 for sequestration considerations. Once coal seams become depleted of methane, the same pore space that held the methane is available for long-term CO2 storage

Significance: Liquefied Natural Gas (LNG) is the 3rd biggest export earner for Australia. Industry is currently targeting regions where gas is easy to extract, and the challenge is to develop new technologies for increasing permeability in other regions and to predict gas production levels as a well depletes. My research supports industry by providing new technologies and new capabilities that helps them maintain and extend their position in the world market.

Main collaborators: Santos, Origin Energy, Arrow Energy, QGC, UQ Centre for Natural Gas, School of Earth Sciences (UQ).

Sequestration of CO2 as Stable Mineral Carbonates

Mineral carbonates are known to be stable for millions of years and so conversion of CO2 emissions to solid carbonate is an attractive solution. My background in manipulating solution equilibria to achieve desired effects led me to establish novel chemical routes for making Mg-carbonates from CO2 and either Mg-silicates or Mg-rich tailings. Given that Mg-silicates can contain Ni the process can be aligned with the current process for Ni recovery. Furthermore, the process can extract CO2 from the atmosphere and can therefore offset the release of CO2 elsewhere.

Significance: Technologies to mitigate against CO2 emissions are of unparalled importance. One of the major challenges is keeping the cost low. Using clever chemistry and combining CO2 sequestration with existing mineral processing operations that produce valuable commodities could enable it to work commercially.