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blogfast25
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Ever precipitated an insoluble fluoride? Going by NdF3 and CaF2, the precipitates are quite slimy, gelatinous
barst**ls. No sandy, easily filtered off substances.
What you suggest is possible, just not very easy.
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j_sum1
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I used CaO as a flux. (Admittedly on this run, I did not dehydrate my calcium sulfate.)
The reaction was quite interesting. I got a clean-burning reaction with no sputtering. It seemed to be very hot but not at all violent.
The product was a single cake of solid material about 20mm thick and 80mm diameter. Maybe a bit like a hockey puck. It was light coloured and dusty
on the surface. Breaking it open showed that the light coloration was only a mm thick. The interior was a charcoal grey colour with fine needle-like
Ti crystals lined up in parallel through the puck. They were finer than the thickness of a hair and sparkled somewhat in the light. But they were
obviously embedded into the surrounding slag. I didn't get any nice nuggets of metal.
Interestingly also, there was no sulfide smell -- not even much when treated with acid.
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blogfast25
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Quote: Originally posted by j_sum1  | I used CaO as a flux. (Admittedly on this run, I did not dehydrate my calcium sulfate.)
The reaction was quite interesting. I got a clean-burning reaction with no sputtering. It seemed to be very hot but not at all violent.
The product was a single cake of solid material about 20mm thick and 80mm diameter. Maybe a bit like a hockey puck. It was light coloured and dusty
on the surface. Breaking it open showed that the light coloration was only a mm thick. The interior was a charcoal grey colour with fine needle-like
Ti crystals lined up in parallel through the puck. They were finer than the thickness of a hair and sparkled somewhat in the light. But they were
obviously embedded into the surrounding slag. I didn't get any nice nuggets of metal.
Interestingly also, there was no sulfide smell -- not even much when treated with acid. |
That's very interesting and hard to explain. The fine crystals point to lack of time to coalesce the metal, of course. But why?
It would be worth trying this again with a KClO3 or KNO3 boosted TiO2 thermite.
I've been meaning to test this in a Classic ferric oxide thermite, CaF2 and CaO, back-to-back comparison... One day...
[Edited on 7-2-2016 by blogfast25]
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j_sum1
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My thoughts were that it didn't get up to a high enough temperature. Or more to the point my setup had a strong thermal gradient which lead to
directional crystal growth and insufficient time for the metal to coalesce. Working with the hydrated CaSO4 can't have helped.
Unfortunately I haven't had nearly as much time in the lab as I would have liked to experiment further. The KNO3 version is definitely on the list.
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blogfast25
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Your earlier observation:
| Quote: | | The product was a single cake of solid material about 20mm thick and 80mm diameter. Maybe a bit like a hockey puck. |
Doesn't really support that (all slag was molten and found at the bottom) but it's possible end-temperature was a bit lower and that reduces cooling
time and thus also time for the metal to coalesce into worthwhile puddles.
I noticed systematically that with TiO2/KClO3/CaF2 I always obtained one single regulus, with
CaSO4/CaF2 always several.
Lots of 'fiddling' with formulations possible, so little time...
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j_sum1
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Hmmm.
I had another look at the result this afternoon and took a pic. Unfortunately, I had crushed up most of it including the best looking pieces and the
photo is just from my antiquated phone. It does not really show well the needle-like crystals that went from one side to the other-- at least in some
of the pieces.
I am not really sure what to make of it. I'm pretty sure that there is metallic Ti there but it is definitely not the result I was hoping for. I
think the next attempt will be using KNO3. I will probably stick with the CaO flux for a while since I have plenty and i do not have much CaF2. I
will attempt the same with silicon as well. (But I think I need some better sand. Last attempt had a really low yield using Al/S. And the byproduct
was decidedly green -- almost Cr(III) colour. I have no idea what was in it.)
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blogfast25
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There seems to be metal in there but very little. Very strange...
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macckone
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Source of fairly pure calcium fluoride.
http://www.nmclay.com/ProductDesc.aspx?code=FLUOR&ty...
This is an artificial product rather than mined from what I can tell.
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MrHomeScientist
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Minimum order 10 lbs! That's a lot of thermite!
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careysub
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Maybe someone would like to order and split it? I would take some.
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semiconductive
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| Quote: Originally posted by j_sum1 |
I am not really sure what to make of it. I'm pretty sure that there is metallic Ti there but it is definitely not the result I was hoping for. I
think the next attempt will be using KNO3. I will probably stick with the CaO flux for a while since I have plenty and i do not have much CaF2. I
will attempt the same with silicon as well. (But I think I need some better sand. Last attempt had a really low yield using Al/S. And the byproduct
was decidedly green -- almost Cr(III) colour. I have no idea what was in it.) |
Sorry to resurrect this after so long, but I was very curious:
Did you ever get a chance to try again?
I bought 20LBS of TIO2, for $10. Aluminum is about $2/LB. I don't have a lot of CaF2.
So, I was wondering about carbonate fluxes, or perhaps boric acid; when I came across this thread.
In the original post, CaCO3 was a contaminant; but that becomes CaO under heat.
Some people also say that CaCO3 will burn with aluminum powder; which means it would create the flux at the same time as the thermite reaction
proceeded. I have both CaCO3 and MgCO3 to experiment with; and I know how to microvawe calcine them into impure CaO and MgO at home. I also have
slaked lime (CaOH).
But I was curious, did the CaO flux ever work out for you ?
The main issue with CaCO3 contamination was that it caused spattering because it out-gassed. But, if the thermite reaction was done in a deep hole
and buried in sand; it wouldn't explode (sand is used for casting steels, and outgassing is common) but I was wondering if that might contain the
spattering.
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j_sum1
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Funny you should mention. Answer, not yet. Shortly after that experiment my lab went into boxes for two years. I have a significant backlog of
interesting experiments to do.
Just today I showed MrHomeScientist's thermite videos to a science class and we will do a couple of basic ones later this week.
I recommend watching the thermite series by the gayest person on youtube. Really good stuff. One of the things he plays with is various
mixtures of fluxes/slags. It is pretty insightful. I am like you: having some oxides and Al powder but not a whole lot of CaF2. A cheaper and more
accessible flux would be welcome. My CaF2 took a while to locate and was quite pricey.
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semiconductive
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I found the videos for the Exotic Thermite, videos 1,2,3. Video 3 Has Ti, in it @ 5:45 minutes in.
https://www.youtube.com/watch?v=LsdesMWC37g
There is supposed to be a fourth video, but apparently was never uploaded? ... the experimenter says in Episode 1, that he's limiting flux to only
CaF2 and cryolite. He only mentions other fluxes in the first video ... but doesn't try any of them.
Also, his thermite mixes for extracting Ti uses potassium chlorate or perchlorate, which outgasses a lot of potassium chloride gas at molten titanium
temperatures. So he looses a lot of the titanium metal as blow-off from the oxidizer.
The process in this thread with plaster, I think, is more efficient.
Perhaps you were thinking of a different person who experimented with fluxes ??
This is what I know of various fluxes:
Cryolite (Na3 Al F6) reduces alumina's melting point to 1000C, and itself melts at 1016C. (Wikipedia) also listed as melting at 950C (Wikipedia). (See
Cryolite, vs. Sodium hexafluoroalumiante): It decomposes rather than boil, but the breakdown temp isn't listed even on MSDS sheets. I don't have any
of this unpredictable stuff.
Fluorspar (CaF2) melts at 1418C BP 2533C
Boric oxide (B2O3) melts at 450C Sublimes ~1500C and BP 1860C (Wikipeda).
So, boric oxide is similar in melting to Fluorspar; except that aluminum dust can reduce it to metal MP 2076C , BP 3207C.
Calcium Oxide is higher melting: MP 2613C, BP 2850C.
I haven't located Eutectic melting points yet for various oxides, so I'm not sure how to calculate amount of flux being optimum except by trial and
error.
I've been thinking that I could perhaps mix aluminum with calcium carbonate or slaked lime, pre-burn it, and then grind up the result to make a flux.
Either that, or microwave Ca[OH]2 with graphite to reach 800C in an alumina crucible. The other way I was thinking to attack the problem, was to make
a separate thermite mix of flux on TOP of the mixture without flux; then the outgassing would be over when the molten flux ignites the Ti mixture
underneath.
I've got a rock polishing tumbler that can be used as a ball mill on solid slag, to re-powder it, pretty easily; but I'm not sure if carbon
contamination will ruin the experiment to make Ti Metal. My experience is limited.
Earlier this year, I tried making a ceramic by partially de-oxidizing titanium with plaster of paris and aluminum powder. That was before I knew
making Ti Metal was possible that way. My idea was that CaTiO3 has a melting point of 1975C and might precipitate out if I only added enough aluminum
dust to remove some of the oxygen and sulpher. The waste alumina is high temperature refactory; So I didn't care that it remained in the ceramic. I
just wanted a cheap high temperature refractory sponge. What I got was a bluish ceramic with extremely large air-holes in it.
I used DAP plaster, just as the OP did (ACE Hardware). But I didn't realize it had so much CaCO3 in it. The MSDS says 20-50%, but at the same time
-- that can't be right; because the hemihydrate is also listed at 20-50% ... (It
doesn't add UP!)
Having 20% carbonate does seem to explain why DAP plaster becomes so weak after setting. I've cast hydrostone branded gypsum then put it in a
ceramics kiln and it will shrink ~20% at 900C -- but it will still he rock hard and strong. But DAP plaster from the hardware store cracks and falls
apart about the second time its heated in a regular kitchen oven. Now I know why.
I followed this threads idea, and mixed the DAP plaster with just enough ROOTO drain opener (H2SO4) to where it no longer bubbled. So, I verified
that DAP has a lot of chalk in it.
Rooto has some organic impurities in it (a few %), but the impurities are soluble in water or alcohol and tend to follow the steam to the surface when
cooked. The picture is of 50g DAP plaster + 591 grams water (2.5 cup) to prevent DAP from setting up hard.
I microwaved the plaster mud for 15 minutes on low to boil most of the water, then kicked the microwave up to high for 40 minutes. The mud shrank to
a dry, friable mass (because it was slightly acidic), with lots of bubble holes inside. I put an alumina plate under the pan, because the microwave
overheats the tempered glass when firing it on high with little water left. It's also to preserve the microwave, when I heat other things at 700 -
800C with graphite. Alumina doesn't absorb much microwave energy and only gets warm to the touch. The porcelain bread pan ... OTOH ... can get up to
200C or so and crack...
If washed with alcohol, the brown impurites in the picture (organics) mostly dissolve. Scraping them off the top of the gypsum may be sufficient, but
alcohol can be easily re-distilled. Alcohol is easier to work with than water, because vacuum filtration is not needed to separate it from they
gypsum again.
I think the microwave selectively heats organics more than water ... so likely that's why the they mostly spattered out of the gypsum onto the dish.
Convenient. 
If the cooked gypsum is put into water again, it turns to mud and won't harden -- So I think it's probably anhydrite. But if there is remaining water
of crystallization, I am not sure.
[Edited on 21-6-2018 by semiconductive]
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semiconductive
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Barium Chloride is apparently a good flux for Titanium !
Let us know when you get around to experimenting with lime again. I'm working on a way to make cheap microwave susceptors out of magnetic sand, so I
can make relatively pure lime. But I'm not there yet ... meanwhile, I found out that the U.S. military used BaCl2 as an acceptable flux for titanium
welds that excludes oxygen.
It has to be dehydrated before use, though.
BaCl2 -- MP 962C BP 1560C
Barium carbonate is fairly cheap; about $4/LB on ebay by seller rakugoldpottery.
$21 delivers 3Lbs to your door. I can make HCl for $2 a gallon 37% ... so that seems like a worthwhile experiment.
I figure posting some thermodynamic data might be useful for future reference...
dH @ 298K, and S at 298K are given in a military report. (http://www.dtic.mil/dtic/tr/fulltext/u2/402468.pdf) The values are not exactly the same as the wikipedia values, even after units conversion; but
they're all in one place for easy reference.
TiO2 dH=-225500 cal/mol S*=12.0 cal/mol.deg
CaF2 dH=-290300 cal/mol S*=16.45 cal/mol.deg
CaO dH=0151900 cal/mol S*=9.5 cal/mol.deg
Na2O dH=100400 cal/mol S*=17.0 cal/mol.deg
BaO dH=-133400 cal/mol S*=16.8 cal/mol.deg
Ti Liq dH=3670 cal/mol S*=8.61 ca/mol.deg
CaF2 Liq dH=-277030 cal/mol S*=27.51 cal/mol.deg
BaCl2 Liq dH=-20000 cal/mol S*=34.6 cal/mol.deg
TiF4 gas dH=-438000 cal/mol S*=71.7 cal/mol.deg
Ca gas dH=42600 cal/mol S*=37 cal/mol.dK
Ba gas dH=490000 cal/mol S*=40.67 cal/mol.deg
So, neither CaF2 nor BaCl2 will react with reduced titanium metal. The barium flux is even less likely to react than the fluoride flux. However, one
of the discoveries in the report is that fluorides react with titanium oxide above 1000C to dissolve titanium oxide.
The fluorides will partially reduce the titanium oxide, and cause it to "stick" in the slag.
So, the gayest person on youtube was wrong about CaF2 not reacting at all. Fluorides do attack the titanium oxide and absorb it into the slag. This
could potentially reduce yields...
Good news/note:
I was able to electro-plate bright clean titanium onto copper wire at about 125C in a proprietary molten electrolyte. (No Water).
So, If I can get titanium metal in crude form with little or no oxygen, I am pretty confident I can make pure titanium metal.
I'll be curious as to how expensive it is (net cost) per pound, because the electrolyte breaks down with time. ( I doubt it's cost effective. )
[Edited on 22-6-2018 by semiconductive]
[Edited on 22-6-2018 by semiconductive]
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