August 26, 2022
Like a Master Chef in his kitchen, the University of Western Australia’s (UWA) Mr Dongke Zhang loves to experiment with new recipes – only his kitchen is a state-of-the art laboratory, his favourite ingredients include iron ore and ammonia and the dish he hopes to serve is “green steel”.
As a globally-leading researcher into decarbonising power-generation, transportation, and steel-making, Dongke is a key member of the team within the Future Energy Exports Co-operative Research Centre (FEnEx CRC) and is leading a program that is investigating how ammonia can be used as a carbon-free reductant of iron ore.
“Everyone in Western Australia knows how critical iron ore is to our local economy and everyone knows how important iron and steel-making is to modern society, but most people are probably not aware the basic process and ingredients for steel-making has remained unchanged for thousands of years,” Dongke said.
“And the fact is our current recipe for iron ore reduction is also responsible for around 7–9% of all human-made greenhouse gas emissions1 – so we need to find a new and improved way to produce steel that is less carbon-intensive.”
As one of the FEnEx CRC’s key projects, Dongke and his team are aiming at unlocking the secret of how the WA iron ores, along with other major iron ores from elsewhere globally, can be directly reduced by ammonia – which can be produced via renewable energy – as well as help design the reactors needed for the process.
Dongke has more than 30 years of experience experimenting with renewable fuels and reductants in the laboratory.
However, the funding and support provided by the FEnEx CRC is now allowing him to experiment on a much larger scale and in a more systematic manner than ever before – with the aim of creating significant new export industries for Western Australia as well as helping reduce the global emissions
“Right now we are focusing on establishing a laboratory-scale pilot reactor that will allow us to conduct world-leading research and experiments on the process as well as modelling which we believe will lead to the development and demonstration of new technologies that can then be deployed at larger scale,” Dongke said.
He said steelmakers have flirted with varying their production methods for decades, but the current global drive to achieve decarbonisation means the business case for transformation is stronger now than ever.
Dongke said his team is working hard to overcome a number of known challenges associated with using ammonia as both a fuel and a reducing agent as well as managing the endothermic reaction (and high temperatures) associated with the reduction of iron ore by ammonia.
“There are multiple angles we need to examine very carefully before we can move from a laboratory-scale testing environment,” he said.
“This includes completely understanding how the physical structure, mechanical strength, and permeability of iron ore, as well as its chemical composition, evolves during reduction in the presence of ammonia.”
Dongke said some of the world’s oldest and largest steel producers are supporting his research including China’s AnGang Group (also known as AnSteel) and Hebei Iron and Steel (BEIS). He hopes to co-develop a larger scale pilot project with one or more of these partners as part of the next phase of the project post the successful laboratory demonstration of the process.
Beyond coke and traditional DRI
Since the dawn of the Iron Age some 3,000 years ago, smelting of iron ore has traditionally involved using a blast furnace which is filled with ore, limestone and coke and subjecting it to hot air blasting and heat which converts the ore to molten iron (known as “pig iron”).
In turn, heating pig iron on a bed of charcoal (which adds about 2% carbon) can then create an alloy (steel).
So for thousands of years, carbon has played three vital roles in steelmaking: a fuel for heating, a reducing agent and as an alloying agent.
Currently coke (which is manufactured by heating crushed coking coal) is the crucial carbon source for around 70% of modern steelmaking.
An alternative method is direct reduced iron (DRI), also called “sponge iron”, which is produced from the direct reduction of iron ore (in the form of lumps, pellets, or fines) into iron by a reducing gas or elemental carbon produced from natural gas or coal.
Dongke’s team is looking at using renewably produced ammonia – which would be produced with low to no carbon emissions – as a replacement for coke in the blast furnace method or the gas or coal in the DRI process.
See here for a video produced by the Australian Academy of Science as part of a series on collaboration between Australian and Chinese researchers for more information on Dongke and his work with the FEnEx CRC.
In addition to the work being conducted by Dongke and his team, the broader FEnEx CRC is also exploring the best way to produce, store and transport lower-carbon fuels such as ammonia and hydrogen. More information is available at www.fenex.org.au.