PM producer Metalysis and the ESA are researching ways to extract metal powder from moon dust –leaving astronauts with something even more precious: oxygen for potential use in life support.

Near the end of a disastrous 2020, news from an unexpected quarter went some way to raise the spirits a little. UK powder producer Metalysis, bouncing back after having gone into administration in 2019, reported that it and the European Space Agency (ESA) had joined forces to research making metal powders in space.

According to the company, the project (entitled ‘The Metalysis FFC Process for Extra-Terrestrial Oxygen Production from In-Situ Resource Utilisation (ISRU)’) will investigate using the company’s Fray-Farthing-Chen (FFC) Cambridge process to obtain powder and oxygen from ‘regolith-like materials in a lunar context’ – i.e., surface moon dust and moon rock. (Figure 1.) According to the ESA, samples returned from the lunar surface show that lunar regolith is made up of 40-45% oxygen by weight, its single most abundant element. An initial proof of concept study of Metalysis’ process resulted in a material with 96% of the total oxygen successfully extracted, for potential use in propellants and life support consumables, and a mixed metal alloy product that can, in turn, be manufactured in place. (Figure 2.)

Interestingly in this case, the oxygen extracted is as important as the powder, since oxygen is essential for sustainable long duration activities in space, and its in situ production could significantly reduce the payload mass that would be needed to be launched from earth, Metalysis said.

‘This oxygen is an extremely valuable resource, but it is chemically bound in the material as oxides in the form of minerals or glass, and is therefore unavailable for immediate use,’ said researcher Beth Lomax of the University of Glasgow, who is researching the FFC process. ‘This research provides a proof-of-concept that we can extract and utilise all the oxygen from lunar regolith, leaving a potentially useful metallic by-product.’

Space exploration

This is not Metalysis’ first foray into space. A previous NASA-funded study, undertaken in 2004, investigated the applicability of the FFC Cambridge process for the electrolysis of lunar ilmenite, known as the Ilmenox process. ‘At the time of this previous work, the development of the FFC-Cambridge process was still in its early stages and had only been proven at a laboratory scale,’ said the company. ‘Since this time, Metalysis has successfully scaled-up its technology, with a further three generations designed, commissioned, and in operation.’

At the same time, the ESA launched its Space Resources Strategy which aims to secure Europe’s central role in global space exploration. According to the ESA, €73-€170 billion are expected to be raised from space resources during 2018-2045.

‘We are really pleased Metalysis is involved in this exciting program; taking an established earth-based technology and applying it to a lunar setting,’ said Ian Mellor, MD at Metalysis. ‘The fact that the process is capable of simultaneously producing both oxygen and metal powders is unique, offering potential solutions to two key areas of the ESA Space Resources Strategy.’

‘In the future, if we want to travel extensively in space and set up bases on the Moon and Mars, then we will need to make or find the things required to support life - food, water and breathable air,’ said Sue Horne, head of space exploration at the UK Space Agency. ‘The involvement of Metalysis in a program that aims to do just that, by producing oxygen on a lunar setting, will showcase the UK’s space credentials on the world-stage and help unlock breakthroughs that bring future space exploration a step closer.’

The FFC-Cambridge process

Metalysis’ FFC- Cambridge process, which was patented in 1998, uses electrolysis to extract metals and alloys from their solid oxides by molten salt electrolysis. The benefits of the FFC process over older pyrometallurgical technology, such as Kroll, are clear. Because it is a great deal simpler and requires a lower energy input, there are obvious reductions in energy consumed, carbon footprint and cost.

To test the process with moon rock, the researchers place the powdered regolith in a mesh-lined basket with molten calcium chloride salt serving as an electrolyte, heated to 950°C. At this temperature the regolith remains solid. They next pass a current through it, causing the oxygen to be extracted from the regolith and migrate across the salt to be collected at an anode. In one test, it took 50 hours in all to extract 96% of the total oxygen, but 75% was extracted in just the first 15 hours.

‘This is the first example of direct powder-to-powder processing of solid lunar regolith simulant that can extract virtually all the oxygen,’ said Lomax. ‘Alternative methods of lunar oxygen extraction achieve significantly lower yields, or require the regolith to be melted with extreme temperatures of more than 1600°C.’

‘This process would give lunar settlers access to oxygen for fuel and life support, as well as a wide range of metal alloys for in-situ manufacturing – the exact feedstock available would depend on where on the Moon they land,’ said James Carpenter, ESA lunar strategy officer. ‘It could also be used to extract useful materials on Mars as well, where pre-processing the feedstock would give pure metals and alloy products,’ added ESA materials engineer Advenit Makaya.

I spoke to Ian Mellor about Metalysis and its foray into the space race.

Liz Nickels (LN): Metalysis has obviously changed focus over the years. Where do you find yourselves right now?

Ian Mellor (IM): Our technology can be both a blessing and a curse – in that the opportunities are so great. We need to focus effort, or we can spread ourselves too thinly and achieve nothing. However, throughout our aim has been to scale up the process with an eye on mass production. The challenge that we face is that we are continually developing a new technology, but once you develop the technology itself, you have to develop the engineering for it at the same time. We must ensure they’re in sync so they can be processed together!

LN: The company has been also producing refractory materials containing High Entropy Alloys (HEAs), which can cope with the high temperatures required in aerospace and gas turbines.

IM: Yes – this is something of definite interest to us, and because the FFC technology is in the solid state, there is no melting, so no issue with different melting points. It is much easier to make challenging alloys that can't be produced by conventional melt. One of the criticisms of HEAs is that there is no obvious route to commercialization. Now, one of the things that we can do with our technology is make bulk powders. And so, in some respects, we can help grow the HEA market to make them a commercial material. Our aim is to show that HEAs are a credible technology with their own market and specific applications.

LN: Aerospace companies are always looking out for new materials suitable for their high temperature applications.

IM: Definitely! We want to give them the confidence to use those materials because they are sitting on the fence. We can bridge the gap between research and production and make it in a powder form that can be used in metallurgy or additive manufacturing (AM). Of course, refractory HEAs are also suitable for space applications such as thrusters or rocket chambers. Materials such as nickel super alloys are very good at what they do, and in terms of future performance, they are very close to their optimal. There are improvements, but they are single digit percentage points, whereas with HEAs, if you can get an extra hundred degrees operating temperature out of them, there’s a big improvement in performance and efficiency.

LN: Tell me about the lunar project. How did it come about?

We’ve been working with the UK Space Agency for the past 18 months, and we sponsored a PhD at Glasgow University with ESA. There are a handful of competing technologies that are also attempting to produce oxygen on the moon, but with the Metalysis process, not only is the amount of oxygen we can extract from the rock higher, but metal powder is an end product as well. It’s a double win!

LN: How will equipment be adapted for the moon?

IM: Obviously, preliminary research has been carried out in the same reactors that we use for our on-Earth processes. On Earth, equipment size, weight and energy use are obviously important, but not vital parameters. You want to run the process as efficiently as possible, but energy is not a premium to the same effect it is on the moon. And so, we are currently translating what works on Earth to what works in space. One of our subcontractors, a company called Added Value Solutions, are looking into how to make the equipment as lightweight possible and evaluating all the different operating issues.

LN: And is any type of moon rock suitable?

IM: Yes – another benefit of the technology is that while the composition of moon rock is different depending on where you are on the moon, we're not bound by location. We can take any moon rock from anywhere, unlike other processes that require a specific material.

LN: What kind of metals are produced from the moon rock?

IM: Predominately it's aluminium, silicon, some titanium and some iron. What’s interesting is whether we will need to separate the metals or use them in alloy form. The powder itself is pure enough to be suitable for 3D printing or other types of metallurgy whether separate or combined.

LN: What has been the company ethos since it went into administration?

IM: Over the last 15 months, there has been a period of reflection, asking ourselves ‘What went right? What went wrong? How do we make sure things go better under the new owners?’ From a commercial point of view, in the short term, tantalum production is still paramount. However, we are also refurbishing a larger scale unit to increase our titanium alloys production in future. In the short term we will have the capacity to produce up to five tons of tantalum and up to 15 tons of titanium per annum.

LN: Of course, you've had Covid-19 to deal with as well. How has that been?

IM: The biggest issue for us has been obtaining the external support that we need for certain equipment. We’ve managed to maintain staff on site following government guidelines, but it's been tricky when we’ve needed to bring somebody in externality. Understandably, not everybody's working. And so that's been quite difficult. There is uncertainty surrounding the supply chain, exacerbated by Brexit, too. But I’m feeling very positive about the future; we’re in a good position coming out the other side.