Exclusive interview: Boston Metal scores breakthroughs in carbon-free metals production

Boston Metal is pioneering carbon-free steel production through its molten-oxide electrolysis technology, securing key partnerships and demonstrating industrial milestones in Brazil, Finland and the US. The company’s progress in anode durability and scalability positions it at the forefront of green steel innovation.

Key takeaways:

  • Boston Metal has partnered with Outokumpu to secure chromium supply for its inert anode technology
  • The company is advancing production with projects in Finland, Brazil and the US
  • Breakthroughs in anode durability and scalability are paving the way for industrial-scale carbon-free steelmaking

Boston Metal’s innovative carbon-free molten-oxide electrolysis (MOE) technology, which can produce iron from iron ore and selected metals from metal oxides, is racking up deployment milestones and breakthroughs in advancing the longevity and durability of its anodes, according to Adam Rauwerdink, senior vice president of business development.

Exclusive insights into carbon-free metals innovation

The latest milestone was achieved on Tuesday September 9, when stainless steelmaker Outokumpu announced a joint agreement with Boston Metal to provide chromium oxide and chromium feedstock from its Kemi mine in northern Finland, giving Boston Metal a potential significant source of chrome it needs to manufacture its inert anodes.

The joint agreement, inked in a memorandum of understanding with Outokumpu, is part of the Woburn, Massachusetts-based company’s long-term strategy for establishing earnings potential for anode technology, Rauwerdink told Fastmarkets in an interview.

The agreement “is part of where we are as a partner and part of where they are as a potential supplier [of chrome] in the future,” Rauwerdink said.

“If you’re familiar with the core of our technology, this electrolysis approach for metals production for steel or some of the ferro-alloys in a fully carbon emissions-free way,” Rauwerdink added.

“We’re using a metallic [inert] anode primarily made of chrome. Long term, the anode is a key area of our intellectual property and so we need to control manufacture [and have access to a reliable supply of chrome], and Outokumpu is one of the major European players in chromium,” he explained.

“There’s an element there of us working with them to understand their raw materials and how those factor into the production of the anodes for our technology,” Rauwerdink said. “The other angle is that some of the earliest applications of the technology are on specialty metals or higher value metals or alloys. They are a leader in stainless steel, and so lots of their side products.”

“Their processes are quite high in chromium or other high-value oxides, and we can use the technology to recover value from those, similar to what we’re doing with our first plant down in Brazil for some other metals,” the executive added.

Thus, Outokumpu can be both a supplier of raw material for Boston Metal’s production of its anodes, as well as a customer for Boston Metal’s technology.

Molten metals electrolysis

Boston Metal’s MOE method operates in a modular cell the size of a school bus that can produce about 10 tons of metal a day. The cell contains molten electrolyte liquid, and iron ore or other metal oxides are deposited in the cell to be processed.

A lot of feedstocks for metals are oxides and Boston Metal uses electricity to separate metal from the oxide, producing liquid metal and oxygen as the sole by-product, the company stated.

The process relies on inert anodes to split the iron oxide bonds (or other metallic oxides) in an electrolyte solution heated to 1600°C. This yields pure liquid iron (or other metal) at the bottom of the cell and releases only oxygen as a by-product, according to Boston Metal.

Importantly, it does not use coal — thus, there are no carbon emissions from the electrolysis process.

The molten metal from MOE can be directly used to make steel, or the process can be applied to produce alloys from metal oxides and can be deployed by mining companies to recover high-value metals from their mining waste.

If the electricity used to power the electrolysis is provided from renewable power generation, it can produce carbon-free steel or carbon-free ferrous alloys.

Ultimately, Boston Metal seeks to enable the industrial scale production of carbon-free green steel at competitive pricing.

Development in Brazil marks a milestone

Another milestone is on the horizon as Boston Metal do Brasil, a subsidiary of Boston Metal, is expected to commission its first industrial plant in Coronel Xavier Chaves in the state of Minas Gerais in the fourth quarter, according to Rauwerdink.

“We’ll be announcing the start of that plant very soon,” he said.

The Brazilian subsidiary celebrated the first commercial deployment of its MOE technology platform for the high-value metals business in April 2024.

The Brazil plant “is taking slightly different sources of waste, but a similar concept, where we’re taking wastes from an existing metallurgical process and further extracting some high-value components from those,” Rauwerdink said.

“It’s not chromium in the case of that project in Brazil — it’s transforming the niobium and tin —but it’s the same core principle,” he noted.

Anode technology advances

Boston Metal also announced a breakthrough in March 2025, when it commissioned its multi-inert anode MOE industrial cell at its facility in Woburn, Massachusetts.

This follows the successful testing of the modular cell technology using multiple anodes in a semi-industrial cell.

The company is also reporting other advances in its ongoing operational testing of two versions of its anode, according to Rauwerdink.

“We have one cell [in Woburn] where it uses one of these full-scale anodes, and we have an additional electrolysis cell at the Boston facility where we use multiple of those anodes in a single electrolysis cell,” Rauwerdink said.

Increasing the number of anodes in a single cell is “how you scale the cell for high volume production,” he explained.

“We have [successfully] validated the multi-anode operation with the inert anode,” Rauwerdink said. “The other big breakthrough we’ve had in the last year is the long-term stability of the anode, [with] substantial improvement over where we were just a year or so ago.” 

“We can now run the anodes for multiple months and finish a duration of a run, and pull out an anode [at the end] that looks very, very pristine compared to what you started with,” the executive added. “That’s [another] key milestone because in the commercial operation for these cells, we intend the inert anode to last in the range of one to three years [and in Woburn] we’ve already demonstrated that [it can be done].”

Advancing carbon-free steel production with durable anodes

The testing of the anodes in Woburn began in 2022.

“Now we’re very much focused on more efficient design of the anode to reduce production cost, and then the overall production cost of the process as a whole, as you talked to production cost per ton of steel, or per ton of some other ferroalloys,” he said.

Founded in 2012, Boston Metal first demonstrated emission-free steel production in its laboratory using its molten-oxide technology in 2013, commissioning its first semi-industrial MOE cell in 2014.

Boston Metal’s core MOE technology was developed by Massachusetts Institute of Technology metallurgical researchers Donald Sadoway, Antoine Allanore and James Yurko.

In 2012, MIT licensed the anode technology to Boston Metal. The company was created to commercialize the metallurgical advances achieved at the college.

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