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Electrowinning of Titanium Metal in Molten Salts.

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NNadir Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Jun-04-10 02:52 AM
Original message
Electrowinning of Titanium Metal in Molten Salts.
Edited on Fri Jun-04-10 03:02 AM by NNadir
Titanium is not a rare element on earth. The oxide, TiO2 is widely used in paints and a host of other applications, including in sunscreens and in photocatalytic materials. The price of purified TiO2 is in the neighborhood of $150/ton.

Titanium metal on the other hand, which is used mostly in aerospace applications, including famously the SR-71 Blackbird spy plane, is very expensive and often difficult to obtain.

This has been a shame, since the metal is superior to steel inasmuch as it is refractory (wrt steel) and light weight (wrt steel). If the frame of the World Trade Center had been titanium rather than steel, the building may have withstood the attack by dangerous fossil fuel terrorists with comparatively minor damage.

The reason that the metal is expensive while the ore is cheap is the same reason that Napoleon III had aluminum dinner service at his palace as a display of his wealth. In former times, the reduction of alumina (the ore) to aluminum was very difficult and therefore very expenive. After the electrolytic molten salt Hall process was discovered, aluminum became cheap and Napoleon's expensive dinnerware became rather ordinary.

I have been aware of a new titanium reduction process that is electrolytic, and was patented about 8 or 10 years ago. This should improve access to titanium metal in the long run.

A recent paper in the scientific literature that I had cause to contemplate touches on this subject.

The paper is "Molten salt applications in materials processing" and the reference is Journal of Physics and Chemistry of Solids 66 (2005) 396401

Mostly the paper refers to the refining of calcium metal, using a novel porous ceramic sheath around the annode.

Some excerpts of the paper beginning with the introduction:

Molten salt processing provides a unique opportunity to process and produce metals where gas-based pyro-reduction, metallothermic reduction, hydrometallurgical methods or aqueous electrochemical techniques are not feasible due to thermodynamic or kinetic constraints. Industrial applications of molten salts have been well recognized for more than century. In spite of the use of high temperature corrosive liquids, molten salts offer unique opportunities. The steel and other non-ferrous metal industries make use of molten salts and slags for refining and precision heat treatment.

Commercial production of aluminum, magnesium, sodium, potassium, lithium, beryllium, etc. make use of molten salt reduction or electrolysis, since any other method is technoeconomically not feasible. Several other reactive metals, such as lanthanides and actinides make use of molten salt processing for extraction and refining. Additionally, the high temperature carbothermic or metallothermic smelting reduction methods for metal production are associated with the generation of significant quantity of waste as slags. Theres a need to develop alternative processes that have low waster ideally a zero-waste generation. Low temperature multicomponent molten salts <1>, as well as room temperature ionic liquids <2> have been developed for materials processing. Molten salts are also finding applications in fuel cell technology. The process described in this paper for producing metals is primarily aimed at complete recycling of process waste. It is also anticipated that the suggested scheme will lower the production cost, since the reductant is electrolytically generated. Significant research effort has been invested in recent times for producing titanium and other refractory metals by molten salt processing. Implementation of this scheme with respect to titanium production is demonstrated <35>...


Further on:

...A number of research studies have been initiated to prepare a waste-minimization strategy <69>. This work describes two aspects of the overall metal production program: (a) electrolytic recovery of calcium metal from theDOR process effluent salt comprising calcium oxide and calcium chloride and (b) use of electrolytically recovered calcium metal in situ as a reductant in a hybrid reactor. There are several advantages of the suggested hybrid process. The process ideally produces zero waste and themetals can be recovered from inexpensive oxides/chlorides without the need for an expensive reductant. Oxygencarbon dioxide and chlorine gases are the only process effluent which can be easily contained. Operational costs include graphite anode, electric power and recyclable salt only. The process is also amenable to alloy production directly by incorporating co-reduction of respective oxides...


The paper ends thusly.

...The process could be conducted under a cover ofnitrogen gas in the electrowinning and reduction chamber, since the metals are not exposed to high temperature atmosphere and are always contained within the salt phase.Fig. 4 shows two such possible designs that have been adopted to produce titanium metal (OS Process) byelectrolytically winning calcium and using it simultaneously to reduce titanium oxide <11>. In Fig. 4a, the calcium chloride salt with electrodeposited calcium is transferred into another reactor where the reduction of titania takes place. In the design shown in Fig. 4b, titania is introduced in the same chamber and the reduction idaffected by the calcium deposited on the iron cathode.

6. Conclusion

Calcium can be electrolytically produced by dissociating calcium oxide in a molten calcium chloride electrolyte. Aporous ceramic diaphragm around the anode is essential for separating the anolyte and catholyte to be able tocathodically deposit calcium. The cell temperature, fluidity of salt and porosity of the sheath are critical in recovering calcium. Ionic diffusion through the sheath is the rate controlling step. A diffusion coefficient in the range of 10K5to 10K6 cm2/s is obtained for a 30% porous alumina sheath for cell temperatures between 800 and 9008C.A hybrid process is investigated consisting of electrowinning calcium from calcium oxide and in situ utilization of calcium as a reductant within the same reactor. Silver, tin, lead and bismuth can be produced by pyrochemical reduction of their respective chlorides and/or oxides with calcium in a calcium chloride medium. These metals were produced as a surrogate for a certain radioactive metal.


Cool. I cite this paper as a demonstration of two of the three R's they teach kids Recyle and Reduce.

We can make better materials cheaper and more sustainably if we invest in intellectual capital.
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phantom power Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Jun-04-10 10:19 AM
Response to Original message
1. k+r
More affordable titanium could be a big deal.
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NNadir Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Jun-04-10 11:20 AM
Response to Reply #1
2. A very big deal. I think it will happen. Thanx.
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kristopher Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Jun-04-10 12:40 PM
Response to Original message
3. Why is this posted to E&E?
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NNadir Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Jun-04-10 01:46 PM
Response to Reply #3
4. Because it's about an environmental issue, specifically waste.
Edited on Fri Jun-04-10 01:49 PM by NNadir
People who know something about the environment may be able to glean that much.

It's also about materials science, which is a key issue in the environment for people who think on a more than superficial handwaving level. For instance titanium can reduce the weight of certain kinds of machinery and thus its energy consumption.

On the other hand, I understand that some people, not familiar with the energy costs and waste costs of metallurgy, would be totally clueless as to why it's here.

Have a nice "pretend to be an administrator" day.
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jberryhill Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Jun-04-10 08:14 PM
Response to Reply #3
7. You'll see.... /nt
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eppur_se_muova Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Jun-04-10 07:28 PM
Response to Original message
5. Bookmarked. I've been waiting for cheap Ti to hit the market ...
ever since the announcement of an electrolytic process way back when. Cheap titanium could really be a game-changer in so many areas -- higher strength/weight would allow a lot of "moreing with lessing". http://en.wikipedia.org/wiki/Ephemeralization
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OnlinePoker Donating Member (837 posts) Send PM | Profile | Ignore Fri Jun-04-10 09:11 PM
Response to Reply #5
8. I'm going to start stockpiling it
That way when Zephram Cochrane needs a source to build the first warp ship, I'll be able to give it to him.
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NNadir Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Jun-04-10 09:50 PM
Response to Reply #5
9. It would indeed be a game changer, comparable I think, with the commercialization of aluminum.
The FCC process is patented, and a tight patent can throw a monkey wrench into commercial development. I have seen great patents do less when they could have done more for reasons that strike me as unbelievable.

I don't know the details here though. I'm not saying the patent is the problem: It could or it couldn't be.

The patent has about 7 more years to go, after which it's a free for all.
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jberryhill Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Jun-04-10 08:13 PM
Response to Original message
6. Hang on kids... there's a punchline coming....
Edited on Fri Jun-04-10 08:17 PM by jberryhill

But it surely was not just the Hall process which led to economically feasible aluminum for the masses.

As you know, the co-inventor of the Hall-Hroult Process was Charles M. Hall of Niagara Falls, New York.

Mr. Hall, who was likely fond of waterfalls as well, was living in Niagara Falls, New York, because he was employed there by the Aluminum Company of America.

Mr. NNadir, would you be so kind as to perhaps tell us why ALCOA happened to choose such a picturesque and lovely town as Niagara Falls for their operations?

I seem to recall a reason why they were located there...


(edit: for the impatient - electron affinity is electron affinity, and ionic bond strength is ionic bond strength, no matter how you slice it)
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NNadir Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Jun-04-10 09:55 PM
Response to Reply #6
10. The answer is obvious and represents why Alcoa and other aluminum companies are in Iceland and the
Pacific Northwest.

Interestingly Alcoa decided to sell electricity rather than aluminum in the Northwest, since the electricity is more valuable.

This sort of thing is, however, the only way Iceland can export its electricity, and it's a good thing too, since they need the money. Their hydro/geothermal electricity is cleaner than most electricity. Those two forms of so called "renewable energy" are somewhat less noxious than others.

Except in places like Iceland though, I have some objection to hydro. I'm rather fond of rivers and continental salt flows, but that's just me.
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jberryhill Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Jun-04-10 09:58 PM
Response to Reply #10
11. Ah, yes... Too cheap to meter.... /nt
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NNadir Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Jun-04-10 10:11 PM
Response to Reply #11
12. And your point in quoting a stupid guy from the 1950's is what? That hydro is too cheap too meter?
I've had really really really really really, really really dumb people tell me here, in this space that solar energy is "free."

Not so, according to the solar industry: http://www.solarbuzz.com/SolarPrices.htm

Personally, I think solar energy should be stripped of its wasteful subsidies, since the world is impoverished and 50 years of super optimistic wishful thinking predictions for it have all proved to be nonsense.

I note that most of the people who end up quoting that moron Strauss when he was discussing fusion energy in 1954 are remarkably silent on quoting Amory Lovins 1976 prediction that the United States would be running on 54 Quads of electricity plus 18 quads of solar energy.

I don't think much of nuclear fusion, and I don't think much of Strauss, but I have zero respect for twits who quote Strass like he fucking matters. He doesn't.

But to anti-nukes, Strauss, who was not an engineer, not a scientist, but merely a government syndic with a bug up his butt, and as many stupid fantasies of a typical anti-nuke knucklehead on this web site, is a kind of god, whose stupid mutterings are the only think one needs to know about energy.

I note that the same asses who make this continuing reference to Strauss don't call for banning coal, oil, dangerous natural gas, wind, or geothermal because the electricity is NOT too cheap to meter.

Nuclear electricity is, when externalities are included, as the should be, the cheapest form of 10 exajoule scale energy on the planet, save maybe hydro, and is, irrespective of what vapid poorly informed people seem to think, the only form of ten exajoule scalable form of energy.

It doesn't need to be "too cheap to meter" to be infinitely superior to everything else. It merely needs to be infinitely superior to everything else, which, happily, it is.

This may be seen by comparing electricity rates in France with those in dangerous gas and dangerous oil hellholes like Denmark.

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jberryhill Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Jun-04-10 10:16 PM
Response to Reply #12
13. I simply wanted to understand your point about titanium

Thank you.
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Name removed Donating Member (0 posts) Send PM | Profile | Ignore Sat Jun-05-10 10:39 AM
Response to Reply #13
16. Deleted message
Message removed by moderator.
 
jberryhill Donating Member (1000+ posts) Send PM | Profile | Ignore Sat Jun-05-10 10:49 AM
Response to Reply #16
17. Thank you for the bonus insight into your character /nt
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kristopher Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Jun-04-10 11:33 PM
Response to Reply #12
14. "Too cheap to meter"
It demonstrates that the nuclear industry has built their entire existence on lies and hype; a tradition you gleefully follow with great zeal.

For example, you attempt a rewrite of history with the totally unfounded claim that Strauss was speaking of fusion power. He was delivering a speech in line with his efforts on behalf of the introduction of commercial FISSION power and there is absolutely nothing in the context that indicates he had anything else in mind.

"It is not too much to expect that our children will enjoy in their homes electrical energy too cheap to meter; will know of great periodic regional famines in the world only as matters of history; will travel effortlessly over the seas and under them and through the air with a minimum of danger and at great speeds, and will experience a lifespan far longer than ours, as disease yields and man comes to understand what causes him to age. This is the forecast of an age of peace."
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jberryhill Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Jun-04-10 11:57 PM
Response to Reply #14
15. Did you get your question answered? /nt
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Blubba Donating Member (4 posts) Send PM | Profile | Ignore Tue Jun-15-10 08:51 AM
Response to Reply #14
18. "too cheap to meter" = fusion
As someone who has actually read Strauss' biography, No Sacrifice Too Great, by Richard Pfau; his memoirs, Men and Decisions; and the authorized history of the American fusion research program by Joan Lisa Bromberg, I assure you the claim is far from unfounded. The public mistook Strauss' statement at the time (and to this day) as a reference to uranium fission for understandable reasons. Strauss was a strong proponent of both hydrogen fusion and uranium fission but since the research into hydrogen fusion was classified the public was only aware of uranium fission. Indeed, only 10 days before he gave his "Too cheap to meter" speech he attended the ground breaking for the Shippingport nuclear reactor and made bold predictions about electricity being generated from "atomic furnaces" in the not too distant future. Of course everyone would assume his "too cheap to meter" speech was referring to fission. But anyone who has read the early history of the hydrogen fusion program would know that Strauss, fueled by enthusiastic progress reports, was obsessed with hydrogen fusion and believed he would deliver the technology to humanity as a symbol of American superiority over the Soviet Union.

The statements Strauss made that are unambiguously about fission only expressed a belief that fission power would be "cost effective" compared to conventional power. Even that belief was optimistic relative to the consensus of the experts at the time.
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kristopher Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Jun-15-10 01:10 PM
Response to Reply #18
19. Another bullshit attempt by nuclear industry to rewrite history.
His statements were clear and in context of the speech he gave THAT DAY.
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Blubba Donating Member (4 posts) Send PM | Profile | Ignore Tue Jun-15-10 03:50 PM
Response to Reply #19
20. Nuh uh.
All Strauss predicted was that electricity would be too cheap to meter. He said absolutely nothing about how he expected it to be generated. It is clear that he believed nuclear technology would provide the benefits he predicted (he was, after all, the Chairman of the Atomic Energy Commission). But there are nuclear technologies that do not rely on fission. But it is obvious you are impervious to facts, no matter how scholarly the sources, that don't reinforce your world view.
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kristopher Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Jun-16-10 01:31 PM
Response to Reply #20
21. He said it in the context of rolling out commercial FISSION power.
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