12 thoughts on “Separating Oxygen And Metals From Lunar Regolith”

  1. –“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,” explains researcher Beth Lomax of the University of Glasgow, whose PhD work is being supported through ESA’s Networking and Partnering Initiative, harnessing advanced academic research for space applications.–

    Yes. Lunar LOX should worth about $1000 per kg on lunar {$1 million per tonne} on lunar surface. And Lunar LOX should worth about $3000 per kg, in low Lunar orbit or about $4000 per kg in high Earth orbits. Which might be bought if NASA explores Mars,
    and later {+ decade} Mars settler could buy at 1/2 or less of that that price. Though Lunar water in high earth orbit by that time might 1/2 price of LOX and it’s possible that Lunar water is bought in high Earth orbit, and high earth rocket fuel made from lunar water is sold to people settling Mars {so Mars guys can buy lunar water, and buy all kinds of rocket fuel cheaper in High Earth orbit made in high Earth orbit- buy the high earth LOX, LH2, and etc.
    Plus once there is market for water in high Earth, water can got from places other than the Moon {water from NEOs, perhaps}.

    “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.”

    When mining lunar water, it would good to sort out the iron ore- sell it to anyone as iron ore. And once there enough iron ore, one make the iron {and steel] and sell the oxygen.
    So I think iron ore will be first metal sold, and those making iron will also make other metals.

    “The process involves placing 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.

    Passing a current through it causes the oxygen to be extracted from the regolith and migrate across the salt to be collected at an anode. It took 50 hours in all to extract 96% of the total oxygen, but 75% can be extracted in just the first 15 hours.”

    It seems to me you first separate iron, and the not iron ore, you could do this. And you could have large iron container to heat ore up to 950°C.

    But I don’t think we going to Moon unless there is mineable lunar water. It’s not a destination to go it. Though a dramatic lower of launch cost might make the Moon a destination, without mineable lunar water- or makes the non mineable water become mineable.

  2. A few years ago some British researchers had some limited success reducing titanium-dioxide in molten calcium chloride using electrodes, similar to using the current process for aluminum. However the calcium was plating out on the anode after a few hours and limiting the current, so they needed a way to keep that from happening. I figured the simplest, no-brain approach would be to order every different heat treating salt from a catalog and try them all, but I wonder if this process is likewise limited to a few hours of useful run time.

    1. That’s the FFC process mentioned in the article linked, George. Elsewhere, they seem to have solved the plating problem, (lowering current density?), but not the problem of the Russian ability to flood the market with Titanium from their old Cold War stores of it. Use of FFC for producing Oxygen on the Moon was first funded by NASA, but then a certain Senator from Alabama decided NASA was spending too much on technology development instead of on SLS.


      It’s good that ESA is standing in for NASA on this application. The nice thing about FFC is that it can be used on a wide range of metals that are relatively light, including Magnesium, Titanium, Aluminum, and several others. It can do this because it moves bound Oxygen to the cathode as free Oxygen that dissolves well in the Calcium Chloride, instead of moving metal ions to an anode. The sintered batch of metal oxide serves as the anode, IIRC. That turns into purified metal, while the Oxygen goes to the cathode. Here on Earth, they use Carbon Cathodes. On the Moon they will use Platinum or some other non-oxidizing cathode to collect the Oxygen gas.

      Fortunately, Calcium is to be had in good percentage on the lunar surface. The thing needing tight recycling, if any, should be the Chlorine. However, since the CaCl2 is used at 800-1000ºC, and it vaporizes only at 1,935ºC, then we shouldn’t see much problem with CaCl2 decomposing in the Moon’s vacuum.

      If this does work, it will be far better than the molten regolith electrolysis we modeled for a lunar ISRU set up in Second Life. May they have great success!

  3. Electrolyzing water to produce oxygen and very valuable hydrogen requires less energy than removing oxygen from metals. So, why is the focus of this article on the production of oxygen. And yes, there is unoxidized iron in the highlands at 1%. So, I would be inclined to start there for the initial metals. For things like aluminum or the other metals then you have to get the minerals with the high content of the metal that you want and start processing from there.

  4. I wonder how closely the simulated regolith really resembles the real thing. This lengthy, but fascinating, article by geologist David Middleton deals with the differences between lunar and terrestrial rocks. It contains a lot of interesting data I had never seen before, which shows that lunar and terrestrial minerals have little in common. In fact, he quotes geologists who have studied the Apollo samples in depth as saying in effect that it was cheaper an easier to land on the moon than it would have been to fabricate the minerals that were returned.

  5. Iron is reduced from ore by combining the oxygen with carbon still. The heat is produced by blasting air through the charge of ore, coke and limestone. Not a process that you could use on the moon, carbon and air being in short supply.

    Most other metals are produced electronically but the ore often has to be processed to remove troublesome compounds. Electrolysis takes a lot of electricity, you’re pushing the thermodynamic ball up a pretty steep hill. Even on Earth, it’s cheaper to produce hydrogen by reforming natural gas than by electrolysis. It’s much easier imagining this taking place on the Moon or in space.

    All it takes is lots and lots of energy.

    1. One thing you have a whole lot of on the Moon is available energy. Focus sunlight on a spot in the vacuum of the Moon, and you have one hell of a furnace.


      IIRC, the intensity is 750 W/cm^2. Though that isn’t a (frikkin) “laser” beam, in the absence of convection and with a reflective cavity surrounding the workpiece you could easily get to within shouting distance of the 6,000 K of the Sun’s temperature. And with solar panels on high, rotating towers at the lunar poles, one could have 24/7 photovoltaic power. Don’t forget, one can build a tower 6 times higher on the Moon than on Earth – higher, actually, since there are no wind or seismic loads to consider.

      1. The Solar Constant At the outer surface of the atmosphere is 1.361 KW/ square meter per:
        so 0.1361 W/ square cm.

        A quick look around found that it takes about 13KW/ Kg to produce Al. Another consumption item is around 0.5 Kg of carbon electrode. The process on Earth requires pretty nasty chemicals, the electrodes are consumed by fluoride corrosion from the salts used. The article Rand pointed to only talks about calcium-chloride which is a much more friendly material. All of this at 950°C.

        The most important resource that the Moon has in this context might be gravity. Doing any of this at 0g would be challenging.

        1. “The most important resource that the Moon has in this context might be gravity. Doing any of this at 0g would be challenging.”

          The low gravity and the vacuum are important resources on the Moon.
          Low gravity allows “faster speeds” and has no significant gravity loss. {Apollo had about 100 m/s of gravity loss leaving the Moon. Mars is less than 500 m/s And Earth is less than 2000 m/s of gravity loss.
          Anyhow in Space with the distances {Space is really Big} human with a life, will want to go fast. And you need gravity wells in space, unless you using stuff like low thrust ion rockets, which don’t get much benefit from gravity wells.
          {And with more powerful Ion rockets they provide a significant micro gravity which last a fairly long time.}

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