Boston Metal wants green steel for everyone


Iron ore producers and steel fabricators are well aware that the steel industry is highly emitting – the nearly 2 billion tonnes of steel produced each year generate around 8% of global CO2 emissions.

This explains the wave of green steel projects launched in recent years, with Swedish miner LKAB and steelmaker SSAB partnering on hydrogen-reduced sponge iron HYBRIT on a pilot scale, and India’s Tata Steel developing the solution. HIsarna to improve the efficiency of blast furnaces.

But US cleantech start-up Boston Metal, an MIT spin-off half an hour north of its namesake city, says these “green steel” projects often face common challenges – the access to both renewable energy and premium iron ore – and that their solution could help with both.

Boston Metal’s solution uses a technique called Molten Oxide Electrolysis (MOE) to convert even low- and medium-grade iron ore fines directly into high-purity molten iron.

The company says this allows for the widest possible supply of raw materials and protects against premium mineral price volatility. The process also allegedly eliminates the need for coke production, iron ore processing, blast furnace reduction, and basic oxygen furnace refining.

Craig Guthrie, editor of Mining Magazine, discussed Boston Metal’s solution with Adam Rauwerdink, senior vice president of business development.

Can you explain the current challenges faced by larger-scale “green steel” pilot projects?

One of the challenges that all green steel technologies are going to face, whether they use hydrogen or electricity like us, is ultimately access to clean, green electricity.

Obtaining this access is something that must be decided now, given how the market will evolve over the coming years and decades.

The availability and pricing of electricity, as well as the production mix on the electricity network, will have a significant impact.

It shows with the SSAB project in northern Sweden, you have good iron ore, you have clean electricity. So that will be an important factor.

We spend a lot of time talking to renewable energy developers about where to place projects.

The other things, and more relevant to the mining side, are just – and I know every iron miner is interested in this – what the generation or production mix will look like in the future to convert iron ore into steel ?

And what impact does this have on the requirements for different qualities or granulates or agglomerates or fines or pieces? How does this compare to the existing infrastructure in the ground?

One of our great advantages is that we can be very, very flexible in this regard. I can use a DR grade iron ore pellet and it will work fine in our process, but so will a 56% Pilbara iron fine. And both work very similarly in our process, with just a bit of extra energy needed to melt all that gangue that’s in the lower-grade ores.

What is your vision of the current state of green steel projects?

Well, one of the things about us is that we’re a venture-backed company. It’s an exciting part of the equation for us, because we don’t have to prove the claim – it pops up everywhere. And you see it across the entire supply chain.

You have the steelmakers with their [environmental] commitments, you see automakers on the demand side, pulling steelmakers to get green steel in their cars.

You’ve seen companies like Ikea want green steel and construction companies looking for it for buildings and bridges. So this side of the market is moving very quickly in a very positive direction.

It’s the demand, the supply is not there yet. Yes, you can recycle junk, but it’s not available in all markets. And so that’s part of the huge effort to bring these new technologies to market.

DRI technology has the advantage of being mature and operating with natural gas. You can get a quick 20-25% reduction in CO2 compared to a blast furnace. But there’s still work to be done to convert that into hydrogen, and the availability of hydrogen alone is a big limitation.

Can you explain how Boston Metal’s modular molten oxide electrolysis (MOE) platform overcomes this problem?

In terms of our process, if you’ve seen a commercial-scale aluminum smelter, you might think that one of our plants is very similar in layout.

It is therefore a modular technology, using individual electrolysis cells. These individual cells are about the size of a school bus, and just imagine lining them up to reach production levels of one million tonnes per year – several hundred cells could reach the one million tonne level.

Inside a cell is a vessel lined with refractory steel, with internal temperatures reaching 1500-1600 degrees Celsius. There are three main components – it’s similar to a battery with a cathode, electrolyte and anode.

The cathode is at the bottom of the cell which is iron, liquid iron – it is the heaviest in mass or density. Thus, it sinks to the bottom of the cell and accumulates over time.

There is a molten electrolyte, which when you add iron ore to the cell, it dissolves and melts into the electrolyte, and the electrolyte is homogeneous, it is equal in everything.

That’s why we don’t really care if it’s fines, granules or agglomerates, because everything will be dissolved and melted.

So as long as you can get it into the electrolyte, just design your power system, and that’s fine.

And this electrolyte is a mixture of iron oxide and other more stable oxides. Silica, alumina, magnesium, calcium, kinds of contaminants that go into iron ore, and these other contaminants.

And that’s the important part for using lower grade ores – when you convert iron oxide to iron and oxygen, those other oxides stay in the electrolyte and become slag. But they are separated from the metal.

Thus you will accumulate these slag elements, these gangue elements in the electrolyte, and produce a pure and pure metal. And then what motivates all this is electricity.

So electricity, there’s a cathode at the bottom, it’s liquid metal, and there’s an electrical connection. There is anode technology, which is the key to this process that is in the electrolyte. And when you pass electricity, through all of this, the resistor heats everything up to 1600 C, and the least stable of the oxides is reduced.

And that happens by design, so you get iron starting to build up at the bottom of the cell, and oxygen is getting released in the exhaust. And then, in terms of collecting metal, it’s very similar to a blast furnace operation. Every day or two you’ll drill it through a taphole, remove the molten metal, plug the taphole, and keep going. Thus, a cell will operate for several years before being realigned and refurbished.

What is the origin of this solution?

What started our business was MIT research. A team there [MIT materials researchers Donald Sadoway and Antoine Allanore] was working on a new anode technology. Historically, aluminum has used carbon as an anode. For the large scale emissions from steel production you don’t want to use carbon anymore, so there has been the development of a metal anode that can survive for a long time in that operating environment and allow the process to work. So that’s what was developed and proven on a lab scale at MIT. It was patented, and Boston Metal was formed to market it – we have the exclusive license to that patent, and we’ve grown a considerable amount since the days of MIT.


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