The steel, cement and aluminium industries account for 30% of global carbon dioxide (CO2) emissions.
A recent article in the Fin Review ($) by Simon Evans and Brad Thompson highlighted the challenge facing the companies that are striving to eliminate or reduce their CO2 footprint by 2030, noting a ‘game-changer’ is needed to ‘unpick tough carbon chemistry’.
Here at ECT, we approach the ‘carbon’ problem from outside the box.
Take lignite (brown coal) drying for example.
High moisture is the problem. It’s the reason lignite-fired power stations emit more CO2 per unit of electricity than black coal or natural gas-fired power generation.
An estimated $400 million has been spent by industry and government over several decades in the quest for a solution to this particular fundamental lignite problem, without success.
They all took a ‘heat and/or squeeze’ approach.
High heat and high pressure require high energy. High energy generally means higher cost, making it a negative-sum game. Processes that involve ‘squeezing’ the moisture from hot lignite resulted in a wastewater treatment issue, adding additional cost.
They weren’t economically viable.
Our Coldry process is counter-intuitive, employing low temperature and low-pressure.
This is made possible by understanding and working with, rather than against, the natural chemistry and physical characteristics of brown coal.
It involves harnessing a natural phenomenon known as ‘brown coal densification’, that causes moisture to be released and the remaining dry matter to shrink and harden. This can be triggered by specific processing conditions, allowing the expelled moisture to be removed via low-temperature evaporation, using waste heat from the adjacent power station.
Low temperature and low pressure equal higher efficiency and lower cost.
The result is the worlds only zero-emission, cost-effective lignite drying technology. The ‘gateway’ to lower-emission power generation and higher value downstream applications like char, gas, fertiliser, diesel and hydrogen.
This approach to innovation extends to our unique steelmaking process, HydroMOR: Hydrogen Metal Oxide Reduction.
But before we dive into HydroMOR, let’s quickly return to the article to get a handle on why the carbon chemistry of steelmaking is so tough.
Evans and Thompson note:
No matter how much they convert to using renewable energy sources to power industrial factories and plants, the chemical reaction involved in making steel and cement produces vast amounts of carbon dioxide.
We understand chemistry isn’t everyone’s thing, so in layman’s terms, here are the basics.
Iron, in its natural form, is found as iron oxide. Commonly referred to as iron ore. It’s iron, chemically bound to oxygen. Hematite (Fe2O3) and magnetite (Fe3O4) are the two main sources.
The chemical process of converting the iron ore to iron is called ‘reduction’.
Chemical reduction via the carbon-based reaction has proven to be the most scalable and economical method.
The blast furnace process is the dominant process globally for primary iron making. Natural gas or coal-based direct reduction rotary kilns are a distant second.
Essentially, iron ore (Fe2O3) and coal (containing carbon) are heated in a blast furnace. The coal combusts, giving off carbon monoxide (CO).
Fe2O3 + 3CO > 2Fe + 3CO2
In this reaction, the iron oxide is reduced to iron, and the carbon monoxide is oxidised to carbon dioxide.
The molten iron is refined and formed into products for use in manufacturing and construction.
In addition to the CO2 emissions from the chemical reaction in the blast furnace, preprocessing of raw materials also required:
- Coke ovens – coke, the source of the carbon for the chemical reaction, is made from coking coal, a process which is CO2 intensive.
- Sinter plant – the iron ore is combined with limestone and heated. The limestone helps deal with impurities in the ore and coal during smelting.
Blast furnaces operate at temperatures of 1300-1500 degrees Celsius, making them energy-intensive. That energy is provided by coal or gas.
The article quotes Mark Vassella, the chief executive of Australia’s largest steelmaker, BlueScope on the importance of distinguishing the carbon needed to achieve the chemical reaction and any CO2 emitted as a function of providing energy to the steelmaking process:
“Carbon reduction is a key focus, recognising that carbon is an essential part of the chemical reaction that processes iron ore into iron,”
“This means a significant proportion of steel’s carbon footprint is linked to the chemistry of making steel rather than the energy required.”
The article goes on to highlight the effort, and struggle by the likes of Bluescope and Rio Tinto to reduce CO2 due to the chemical and heat requirement, neither of which can be supplied by wind or solar.
CO2 capture and storage (CCS) is already technically feasible, but it adds considerable cost.
Hydrogen is briefly mentioned as a distant, aspirational prospect for replacing carbon, as the only emission is water vapour.
The concept of hydrogen-based reduction of iron ore isn’t new.
It’s just that historically, sources of carbon have been readily accessible and affordable. Unlike carbon (think coal, oil and natural gas), hydrogen isn’t found anywhere in nature on its own. Hydrogen needs to be produced, either by splitting water (hydrolysis) or cracking natural gas (steam methane reforming).
Splitting water is energy-intensive (i.e. expensive) and cracking natural gas, while cheaper, is CO2 intensive.
The current barriers to the adoption of hydrogen-based reduction are cost and scalability of renewable hydrogen generation and the cost of storage of electricity for reliably powering and electric arc furnace.
Our unique HydroMOR process is an alternative approach that competes with the blast furnace on cost while delivering lower CO2 intensity, allowing us to bridge the gap between today’s high-emission steelmaking and tomorrow’s low or zero-emission future.
HydroMOR is the most significant shift in approach to primary iron production since the advent of coke-based steel making in 1709, breaking the carbon mould in three ways:
- Lignite – HydroMOR is the worlds first and only lignite-based primary iron making process, replacing expensive coking coal. HydrMOR uses lignite as a reductant and heat source – no other technology does this.
- HydroMOR can use ‘waste’ iron ore fines and slimes, replacing premium lump iron ore. In places like India, around 30% of the ore extracted from the ground ends up as fines and slimes.
- HydroMOR is dominated by a hydrogen reduction reaction, instead of the traditional carbon-based reduction reaction
- Most of the carbon from the lignite is deposited in solid form within the process, reducing CO2 output
- Lower cost plant design:
- HydroMOR employs our unique vertical furnace that works with the natural chemistry of brown coal to produce hydrogen in-situ
- The HydroMOR plant, incorporating Coldry as its front-end raw material preparation stage, is up to 40% less capital intensive than an equivalent capacity blast furnace or coal-based DRI plant
- Relatively low operation temperatures reduce material capital cost of plant
- Smaller equipment sizes, when compared to existing steel production processes, results in reduced land area requirements
- Efficient reaction kinetics result in lower reductant requirements when compared to DRI technologies
- Simple equipment design facilitates low maintenance requirements, high asset availability and long production lifetime
- Simple process flow and high levels of process automation allow for low operational staffing requirements
- Very low water consumption compared with other DRI technologies
How HydroMOR works:
- Lignite and iron ore is combined and dried using our Coldry process to form ‘composite pellets’
- Composite pellets are continuously fed to our unique furnace (continuous vertical retort)
- Gasification of the volatile matter in the lignite produces hydrocarbon gases such as methane (CH4)
- Catalytic thermal decomposition of the hydrocarbon gas produces hydrogen (CH4 > C + 2H2)
- Hydrogen reduces the iron oxide to iron, producing H2O or water-gas
- Reactions within the retort result in the chemical looping of hydrogen, amplifying reduction reaction
- Much of the carbon is deposited in solid form, reducing CO2 emissions
Not only does HydroMOR offer a hydrogen-based chemical pathway today, but it is also characterised by two distinct additional economic advantages:
- Alternative raw material opportunity
- Lower plant cost
The ‘alternative raw material’ opportunity
There exists a vast, ‘above ground ore body’ in the form of iron ore mine fines and slimes, and industrial wastes such as mill-scale and nickel refinery tailings.
Current processes can’t utilise fines and wastes without expensive pre-processing. HydroMOR liberates this often stranded resource in an efficient, cost-effective manner.
HydroMOR enables a lower cost primary iron production pathway by leveraging two unique features:
1. Decoupling iron making from coking coal
By utilising the rich organic chemistry within low-rank coal, the HydroMOR process utilises a different chemical pathway to deliver a high-quality product without the need for high-quality coking coal, resulting in decreased raw material cost and diversified supply options.
2. Exploiting the ‘above-ground ore body’
By harnessing the vast ‘above ground ore body’ that exists as mine tailings, fines and slimes and from industrial wastes such as mill-scale and nickel refinery tailings, HydroMOR is able to leverage sunk mining and processing costs by providing a waste remediation solution that turns a contingent liability into a revenue stream.
Tailings storage locks up significant swathes of valuable land. HydroMOR minimises waste, releasing land for productive use.
Where to next?
HydroMOR is poised to progress to pilot scale, ahead of commercial deployment.
The successful commercialisation of HydroMOR would be a game-changer for countries with brown coal resources, providing a new, high-value application for a currently low-value, much-maligned resource while reducing steel industry CO2 intensity compared to traditional carbon-based methods.
HydroMOR isn’t a silver bullet for the entire industry globally, but it’s certainly a significant advancement and is the only process under development that can reduce CO2 intensity without additional cost.