Steel retort design for making Na metal for review

I want to make Na metal chemically, because it seesm a lot easier than with the usal electrolysis of NaOH (which dissolves the Na metal) or NaCl/CaCl2 mixture which requires separation of the anode and cathode sections .

The reaction is :

Na2CO3 + 2C --> 2Na + 3CO

This reaction is favorable @ 1100oC and was still used commercially in the late 19th century.
Now I want to make a steel tube retort to run this reaction. Small samples in a test tube (the latter did not survive, melted like plastic) did release Na vapor due to the bright yellow sparks escaping from the reactants.
I already made a steel pot (made from a steel tube which bottom is squeezedin a vise and then welded together) with a 3/4 steel tube screwing cap but I'll make a steel tube to capture the vapor and collect it under mineral oil. I pot the end of the tube not too far under the oil level to prevent the oil coming in the retort when pressure lowers due to e.g. the flame moves a bit away.
I'll put the retort in a propane furnace heated to 1200oC
Of course I'll take safety precautions: do it outdoors , wear a face mask and gloves.

Does anyone have suggestions ?







[Edited on 2010-9-15 by metalresearcher]

Awesome its nice to see another person who is on the side of non-electrochemical alkali metal production . After a long hiatus from home experimentation I have started a new project similar to yours. My aim though is the production of potassium utilizing the KOH & Mg termite. The method was derived from the discussion's in unconventional sodium. Since KOH & Mg turnings are readily available to me this method is unmatched.

The reaction proceeds as follows:

KOH+Mg--->MgO+K+.5H

The reaction is very fast (almost explosive for NaOH) and it is initiated at a relatively low temperature. The nice thing about it is it can be applied to a variety of alkali metals including Cesium. In the system I have designed I will purge the inner chamber through a ball valve with argon before igniting the mixture. After the mix has reacted fully I will continue to heat the retort until its about 759°C when the potassium will volatilize into the copper pipe and condense. The condenser will be kept at a temp of about 65-70°C via a recirculating heater keeping the K liquid and allowing it to collect in the mineral oil catch pan.

Conveniently this reaction is well bellow the melting point of my reaction vessel. I do however intend to plate the inside of my steel pipe with nickel to help reduce the corrosive effects of the hydroxide on the iron.

And now for the best part photos :

It probably would be, but K2CO3 is not nearly as available to me as KOH. And the reaction isn't that bad with potassium its fast but not really explosively according to the thread i mention above so I'm not to worried. I'd only be concerned if I needed Na, but lucky for me I have enough of that to last me for a long time.

FIRST TRY ... FAILED :-(

I just did my first attempt but despite heating the (small)vesselto 1100oC I saw no sodium in the oil.
In the meantime I bought steel tubing + caps like @NREV did. I think the vessel as I used it now was not completely sealed as Isaw bright yello flames (see in the video) in the furnace and a little white smoke (Na2O ?) appeared.
I think that the threaded parts are hard to seal .

Other ideas like stainless steel retort do not make much sense as SS is as weak as 'ordinary' steel and oxidizes as easily. The only real solution is using Ir, Re or W as vessel material but these metals cost thousands of $$$ per kilo. And graphite crucibles (which I have) can be a solution too but ... how to seal ???
I bet the facilities producing Na metal commercially by this process at the end of the 19th century used black steel as well.

Here a video of which I did this evening:

http://www.youtube.com/watch?v=fNJgH52Ff1s

UPDATE:

I was unable to unscrew the bend + tube from th vessel. So the only option was the .... angle grinder .



And here a closeup of the open cut vessel:



[Edited on 2010-9-17 by metalresearcher]

Awwww shit.... and my 70amp 12vdc adjustable power supply turned up this morning as well.

A young guy into HAM radio donated it to the cause (science), on my birthday too!

There is a lot of stainless used for kitchenware / household items that is simply stamped, where precise wall tolerances, stress lines, welds and all the rest aren't an issue.

Maybe you could find something suitable digging around the local cheapo stores (e.g. I have a stainless steel toothbrush holder, a cup like thing, that cost next to nothing). Then nickel plate it for super duper corrosion resistance.

I'm not sure how you're going to oxidize the stainless with a reducing atmosphere inside it (unless you mean the outside).

Also, check the temperature on that spout coming out of the heating pot, you'll want the entire thing above the melting point of sodium. You'll probably also want to purge the pots with an inert gas prior to starting.

Bartlog is also correct about the temperature. People go on about "but jet fuel doesn't burn hot enough to melt steel". It doesn't need to melt it when there's thousands of tons of building sat on top of it. Anyone who's held a long, long rod of steel knows it's like spaghetti even when it's cold. The steel will loose a gigantic amount of strength once it goes over something like 700 - 800C, from memory. If the 'jet fuel not hot enough' stuff was worth a single grain of salt, boeing would be making engines out of wrought iron. They actually make them out of monocrystalline titanium and other super alloys, and stainless. There's probably some reasoning behind that.

You should check out the videos for how they do the turbine and fan blades. Unbelievable stuff. The fan blades are actually hollow, and cost about £20 -30k or something, EACH.

As for vocoders, any tune that involves a vocoder is going to be a guaranteed hit with me.

"Just on the border of your waking mind
There lies... Another time
Where darkness & light are one
And as you tread the halls of sanity
You feel so glad to be
Unable to go beyond"

John <----- WHERE ARE THE REST OF MY PRESENT GUYS!?

Left to right, a coffee filter, cocktail shaker (stirred will do), kitchen storage thingy (spices / sugar / flour), cups, 100% stainless thermos


I particularly like the drinks shaker and the storage thing. Both have friction fit lids and the walls are ready for heating (the shaker LOOKS like a crucible). They can all be found for very little money (the thermos was about £5 or something).


[Edited on 17-9-2010 by peach]

I was sure I saw one of the crucible companies in the UK doing lids at some point, Morgan (Salamander), but I can't see them on there now. If you're Europe / UK side, you could give them a ring.

The guys who do investment casting of jewellery and dental fixings are likely candidates I suspect, they usually have nice crucibles, but not the "How much did you say again?" end of nice.

{Edit}Are you in the UK? I thought DeWalt had made Bosch illegal in the US My last Bosch grinder actually died, early. And when I opened it up, I discovered it was 100% unserviceable, an odd thing for a German brand. I switched to a mondo 3hp DeWalt, that gets things moving alright. But the trigger switch also jams in the ON position when grit blows into it. 3HP, a few thousand RPM, mit blade and jammed ON. Hmm....

[Edited on 18-9-2010 by peach]

Quote: Originally posted by metalresearcher

FIRST TRY ... FAILED :-( I just did my first attempt but despite heating the (small)vesselto 1100oC I saw no sodium in the oil.

Quote: Originally posted by NERV

Since KOH & Mg turnings are readily available to me this method is unmatched. The reaction proceeds as follows: KOH+Mg--->MgO+K+.5H

@Formatik

The reaction *is* favorble @1100oC according to this site : fill in 1 mol Na2CO3 and 2 moles C and this was used commercially in the 19th century before that electrolysis of liquid NaOH or NaCl was more feasible.
I did address the suckback issue as I keep the level of the ducking tube less than 1cm below the oil level so when the retort sucks back it drags only the oil above this level and that is not enough to fill the entire tube to get into the hot vessel.

I just did my second attempt by using a sealed steel container (see the photo in my first post on top of in this topic) now I heated it more by using forces draft propane and within five minutes it got yellow hot which required dark goggles to see anything rather than yellow void which means as much the temperature is 1200-1300oC way enough to start the reaction. But what also happened is that I saw again bright yellow flames from the bottom of the vessel and then fumes escaping which required to wear a mouth mask as these fumes are probably Na2O.
When it did not react, no fumes can escape because Na2CO3 vaporizes at white heat @ 1600oC according to http://en.wikipedia.org/wiki/Na2CO3 .
The bubbling in the oil bath stopped as well which means that venting took place from the vessel itself
Then I stopped the furnace and opened the furnace lid and took out the retort and saw this:



and a more detailed view:



which tells that the steel is probably chemically attacked by the liquid Na2CO3.
It was not hot enough to melt (which occurs @ 1500oC).

Next time: graphite crucibles glued together with stove kit ???
Or iridium / rhenium ???


[Edited on 2010-9-19 by metalresearcher]

Quote: Originally posted by metalresearcher

@Formatik The reaction *is* favorble @1100oC according to this site : fill in 1 mol Na2CO3 and 2 moles C and this was used commercially in the 19th century before that electrolysis of liquid NaOH or NaCl was more feasible.

Welded retorts are useless > 1000oC

New try: no leaks anymore

Here again I tried Na2CO3 + powdered charcoal:

Heated it till a bright yellow 1200-1300oC:



It appeared brighter than on the photo I needed dark goggles to view into the furnace and I saw the outside of the retort was covered with molten Fe3O4 due to the slightly oxidizing flame.
The oil bath remained bubbling and no fumes coming off the furnace. Then I stopped it after running 15 minutes and let it cool down. Now the welds kept sealed.
After cooling I tried to reopen the threaded knee but is was so tight that the only option was:



After applying the grinder here a detailed view of the outside retort (was a 3/4" steel tube with a bottom welded onto it). The damage due to oxidizing is clearly visible.
After opening up I saw some unreacted stuff at the top of the retort, due to the narrowness of the retort.



Here a detail of looking into the condensing pipe into the oil bath. Possible some tiny amounts of metallic sodium might be there.



So I filled it with water. I did not see a reaction but I heard a very little bubbling probably due to reaction of a few milligrams of Na with water.

The next time I will use a wider steel tube which is not zinc plated (easier to weld) and thus a larger amount of mixture in it.

Quote: Originally posted by metalresearcher

Unlike the Na3CO3 + charcoal mix, no fumes appeared but bright yellow flames from the (welded) bottom of the retort and after cooling I saw holes (slag from the weld dissolved in liquid Na2CO3 ??) and the bottom of the furnace was glassy. Maybe the slag holes in the weld are the result of my poor welding experience and/or the steel was zinc plated.

Quote: Originally posted by peach

With the inert flush, as much as I like Nitrogen, Argon would probably be a good idea at such high temperatures. Helium would most definitely not be a good idea (it'll blow out quickly at those kinds of temperatures, and it costs a bomb).

Quote: Originally posted by peach

I'm right in the middle of trying to make sparkly glow in the dark paint, so I'll have to come back and reread the new bits more thoroughly later. With the inert flush, as much as I like Nitrogen, Argon would probably be a good idea at such high temperatures. Helium would most definitely not be a good idea (it'll blow out quickly at those kinds of temperatures, and it costs a bomb). You could give a nickel plating a try before going to the higher priced options. Len is using Nickel, albeit at significantly lower temperatures. He is also using a lot of current however. If that's not good enough, plate the crucibles with something from the Platinum group. Iridium is a good idea (for those unsure, Iridium is better for this kind of thing because it can withstand huge temperatures and still not begin reacting, whilst also retaining it's strength; it's used in some ion gauges for vacuum work, where the gauge needs to remain close to perfect and tiny traces of atmosphere in the pumping down stages may begin creating skin oxides, and to prevent the gauge mechanically distorting / skewing when it gets hot). Nickel is cheap enough to do the entire crucible from it. The platinums are going to make you bankrupt before you've heated anything. Plate the suckers on. The bulk material can act as the support, with the platinum group acting as the liner. If you're not stirring away or grinding things up in there and are gentle cleaning it out, the liner should remain in tip top condition for a good while. They use this same idea in high pressure reactors. Steel for the chamber, borosillicate / quartz / teflons for the liner (FEP, FPA, EFTE & PTFE are all almost identical in terms of their chemical resistance, but differ a little with regards to their electrical / mechanical / thermal processing properties). If you need to use a pure platinum group metal for the entire crucible, the idea is out the window immediately versus Len's electro method, which is going to be far cheaper and it doesn't involve cylinders or thousands of degrees. [Edited on 21-9-2010 by peach]

For high temperature work I made this metal flask, and for sealing threads and space between upper and lower portion of flask I used sodium silicate paste with some filler (rated to 1350 C).

When welding galvanized steel, you will poison yourself without proper ventilation. Zinc catches on fire, and there is cadmium in fumes from this smoking flame (old welder told me that). To weld such steel soak galvanized parts in dilute acid for one day (or to the point when hydrogen is no longer seen bubbling).

In one post there was mentioned teflon for use in sealing threads... For such temperatures its foolish, go read on decomposition products of teflon and how long those nasty substances stay in your system (years!).

Read many posts from you all, thanks for that, but is there anyone who really used the retort setup ?
I am curious about experiences on steel retorts (or what their remains are) after heating to temps over 1000oC.

Saturday I'll build a new one to this design:




[Edited on 2010-9-23 by metalresearcher]

It is very difficult to make the retort airtight

I got some 2" black steel tubes from a scrap yard, so I tried the design as sketched in my previous post. I welded a top and bottom onto it and a 1/2: knee on the top (after dezincking the knee as it was galvanized.
Then I filled the retort with Na3CO3 + C but the result was .....

Leaking welds on the top of the retort. It is very hard to make the seams airtight (read: sodium vapor tight).
In the picture below the yellow flame of the leak is clearly to see. And the oil stopped bubbling. So I stopped the furnace and let it cool down and will reweld the seams.

@Rogerywemaw: how did you keep the P4 making setup airtight ?



[Edited on 2010-9-25 by metalresearcher]

Quote: Originally posted by metalresearcher

@Rogerywemaw: how did you keep the P4 making setup airtight ?

Smaller scale attempt no leaking anymore

Now I performed a smaller scale test by just using a 15mm steel tube (1/2" inner diameter) of 30cm long which I bent 90 degrees in the center and squeezed together on one site which I welded together. Then I filled it with Na2CO3 + C so it just filled on the closed side of the bend. So no threads or other welds anymore which can leak...

I put this closed end into a furnace and the open end in a beaker with motor oil. Then I heated the furnace to 1200oC and saw bubbling in the oil. Furthermore I saw some precipitation in the oil which I will investigate later.
No leaks appeared as I did not see any sodium yellow flames coming from the bright yellow hot mini retort (bottom right picture: the bright object top right in the picture is the retort).

I think that the retort of the test yesterday leaked because of the poor welds.

@Rogermeryaw: you are probably a professional welder I am not as I waste 8 electrodes with 100 anp to weld 2 steel plates on both sides of a 2" steel tube. I feel embarrassed that my welds are such a poor quality....




UPDATE : After one hour the precipitation settled at the bottom of the beaker with oil and below a picture of the bottom of the beaker:
Probably no sodium metal but I don't know what the white subsance is.

UPDATE AGAIN: I peeled some substance out of the retort tube and dropped it in water. Yes some bubbling appeared !!!
Then I poured some water in the tube and it started bubbling and hissing and a yellow spark appeared .
YES !!!! I HAVE MADE IT !!! SODIUM METAL !!!!!

But it was frozen in the tube before reaching the oil bath. So I have to preheat the tube a bit more, over 98oC (Na 's melting point).






[Edited on 2010-9-26 by metalresearcher]

Quote: Originally posted by metalresearcher

@Rogermeryaw: you are probably a professional welder I am not as I waste 8 electrodes with 100 anp to weld 2 steel plates on both sides of a 2" steel tube. I feel embarrassed that my welds are such a poor quality.... [Edited on 2010-9-26 by metalresearcher]

MR, make sure your metal is as clean as you can get it, that the rods aren't the ultra cheap crappy kind and that the welder can dump enough current through to get it going properly.

To clean things, use an abrasive disc, a sanding disc or a twisted wire wheel cup. All three in an angle grinder, clean just prior to welding so it can't recontaminate in the meantime. If you put a 75mm sized wire cup in a 3hp angle grinder, it'll annihilate anything on contact and the finish will look polished to a mirror, without grinding the metal down. And, they squeeze into all the gaps, unlike a disc. But you seriously need a face shield, as they spit bits of wire out all the time (EYES).

Cheap electrodes won't flux / ignite properly. A guy I used to work for bought 4, 5kg boxes of some that were being thrown out from somewhere. They were being thrown out for a reason, they were horrible. I've also stick welded with nice 316's and the quality is superb, without even trying it can look like it's been done with a TIG torch and needed years of experience.

The current is another issue. Theoretically, the arc is hot enough to melt the puddle properly. In practice, if there's not a good amount of current happening, it'll run too cold, end up brittle, not properly stuck etc. Whilst working for that guy, I told him I'd found a 400amp DC TIG set for £150. He was laughing and telling me I hadn't. Then I turned up the next day with it and he spent the entire week trying to bargain it back off me (it was a Thermal Arc, the purple ones). I managed to burn out the industrial, 3 phase wire fuses in the workshop by turning it up.

If you need to, 'cheat'. Use a stick of wood or something to guide the stick in a smooth, constant line. They do it industrially so...

That aside, CONGRADULATIONS on finally getting something that looks right, you've certainly persevered and rapidly as well.

I have a question. Are those normal house building thermo blocks you're using as insulation? Have you got much experience with using them for that? And how well do they hold up?

I have some real high content alumina refractory. It's incredibly tough to cut and is used to line the ladles in iron foundries (so it has the maximum temperature rating available for regular, ceramic type refractories). But it also has fairly poor insulating properties. It's used to get the temperature down to the point where another liner, on the outside, can block the rest of the heat. I've often wondered about, but not tried, using those thermo blocks as an outer liner for the alumina stuff.

Len has informed us, helpfully, that regular glass wool melts around 800C, so that's another possibility.

I've heard that things like those blocks gradually fall apart over repeated high temperature runs. True, false, how true?

75mm £4, 100mm £7. Used 230mm (9"), 1800W+ (2.5 - 3hp) Makita grinder... there's one on eBay for 99p at the moment.


[Edited on 26-9-2010 by peach]

Quote: Originally posted by peach

Not sure about the fatty acids thing, but it may be an idea to stick with the motor oil. I'd start bumping the safety up by simply putting a loose fitting lid over the oil. Provided it doesn't start to boil, the lid should help smother it if it catches.

Heatsink / water cooling ideas are good and simple to incorporate. Although, I'd go with the heatsink one over the water, since the latter could easily make things exponentially worse if something goes wrong (see; Mythbusters, kitchen fires)

The flash point of typical motor oil seems to be around 200C (400F). A number of solders melt around that temperature, so a simple, cheap way to watch for it is to stick a bit of solder wire on the tin and look out for it going liquid. Rest it at sloping angle and it'll run from one place to the other, making it easier to see.

The metal processing guys often do something similar, with sample blocks of clean metals to judge the temperature reliably. There are also a number of crayons you can get to write on blocks. The crayon melts when it's hit that temperature, which is handy for annealing / tempering (not the same thing) and so on. If you watch videos of them making steel ingots etc, you'll sometimes see them scribbling on the blocks with things like this, whilst they're steaming hot.

Medical units can buy bags with similar things built in, that read STERILIZED when they've been cooked in the autoclave for the correct amount of time.

Going yet more off topic, they do something similar with gamma ray processing. Stick tags to the pallets to check they've been dosed correctly.

Temperature indicating crayons, from 40 to 1200C in 120 steps at 1% accuracy


[Edited on 27-9-2010 by peach]

Good ideas !
Now I made two other small scale retort pipes one of them (the middle in the picture below labeled 'Na') was used before with the larger retort last Saturday. At that experiment Na vapor was leaking from the retort.
Now I heated it to red hot in the middle to bend and after heating I quenched it in water and what happened .....?
Hissing and bright yellow sparks appearing and pops with a yellow flash which was clearly that sodium metal wast still in the tube (despite the tube was lying for two days in open air and a part of it heated to red hot shortly before).

A made a new one from the same tube (labeled 'K' on top of the picture) which I will use for K2CO3 + C for making potassium metal.

Now is the time to up the care level, as it sounds like you're on the way to a lump, possibly of special K.

Just found a solution for the oil capture :I use a 32mm (1 1/4") test tube filled with motor oil in which the condensing tube is partly immersed. Due to the narrow nature of the test tube the suckback issue is addressed as well.
It fits any 15mm outer diameter steel tube regardless for very small scale or much larger scale. The test tube holder has an adjustable height.

That's a smart bit of thinking, particularly the holder on the bottom with the adjustable height. Elegant, simple, effective.

{edit}Stick a small computer fan on there pointing at the bottom of the tube?{edited}

[Edited on 28-9-2010 by peach]

Thanks for your comments. I tested it and it worked fine. Now I tried potassium now with K2CO3 + C but the bottom of the retort got overheated / attacked / melted ????
On the right there is the weld, I saw it nearly white hot in the furnace what happened ??
Melting cannot occur as steel melts @ 1500oC, but to be honest I was rather close due to the blinding light yellow glow ....
I can peek my S thermocouple into the chamber but temperature is VERY HARD to measure. When the moving air in the chamber i, sday, 1300oC then the steel can differ more than 100 degrees.

What do you guys think about the damage to the retort ?

Tomorrow a next try.

Quote: Originally posted by metalresearcher

Good idea that U-tube, as I have destroyed two squeezed-end-tubes tonight with the same leaking issue at the weld at the squeeze.

Sweet! (pumps fist in air), unfortunately, now encouraged, i'm sure to spit out hundreds of useless stupid ideas chasing that feeling.

Next attempt: I tried the U-tube , thanks to @Panache.
I bent a 15mm pipe and filled it with the rxn mxture Na2CO3 + 2C a little bit more C than stoiciometrically requirfed (weight ratio Na2CO3 : C = 106 : 24) to remove the last traces of oxygen in the vessel. I had a receiver made from a glass jar of which the top half is cut off.
I had to tap with a hammer to the tube to ensure the mixture gets in the U.



Then I put the stuff into the furnace and protected the oil bath with a piece of Fermacell fire retardant board with some pieces of Rockwool roof isulation on it. Here the setup except the lid of the furnace.



After a few minutes the oil began to bubble heavily and sodium colored flames appeared above the Fermacell board and the tubes got yello hot so I had to lower the flame.



But despite all these measures, the oil caught fire. I put some Rockwool blankets over the receiver Then I saw what I feared: ywellow flames and white fumes from the furnace and looking inside I saw bright yellow flames coming from the hotetst part of the U. The 9/11 effect: overheating steel even without seams it collapsed under its own weight like the Twin Towers.
Now the oil is still cooling and I am curious whether some sodium is there......

This WAS the retort ....



As seen here it is clearly MELTED .....

I googled many times to search how commercial production took place by the end of the 19th century.They also used this approach. As there was no stainless steel at that time what did they use for the vessel ??

Later on I poured some water into it and this happened .....

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[Edited on 2010-10-2 by metalresearcher]

Looks like you have sodium there.

Nightinhawk, a guy on youtube who's fireworks cracky, has had a lot of luck with the NaOH / Mg thermite style pot method.

There are a lot of variables in the retort. If you're not going with upgrading the steel yet, I would suggest knocking the atmosphere out as a variable altogether, by purging it with argon. If you don't already have it, or use it on a regular basis, or have a neighbour who can donate his cylinder for a few minutes, it may be cheaper and easier to change the steel.

In the olden days, I expect they managed by dealing with low yields, tons of fiddling and a lot of care. Knowing the olden dayzers, they were probably using very thick walled tubing too.

I seriously think you should upgrade to stainless. There are grades specifically designed to retain their strength at high temperatures, for use in jet engines. I'm sure it's possible with lesser materials if they were doing it all the way back then, but those were their particle accelerators at the time. The stainless will be more expensive, but not by any significant amount compared to the high purity crucibles and platinums.

Surely you must be getting tired by now of seeing those things seize up / melt? The tiredness and your time has a price as well.

A fairly obvious warning that I doubt you need, but be careful adding water from something like a cup or watering can. I've seen one guy do the same in one of these videos and the sodium spat back at him, and got him. If you suddenly make a break through, there could be a lump of it trapped in the tube, which may then explode when the watering can method is applied.

My own silly story along those lines... I was melting lead water mains pipe in a pan buried in a fire. I knew there was water still on it because I could hear the violent boiling as I added them and they melted. One of them didn't play along and, with the bore acting as a barrel, shot molten lead 12ft across the garden in a shotgun effect. Luckily, I was siding to the side of it when that happened. But that's only boring old lead.

I don't know how true it is, but I've heard stories from people running industrial induction melters that have mentioned something to do with the load being incorrect, or the power supply, and the magnetic activity actually shotgunning the charge vertically back out.

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[Edited on 1-10-2010 by peach]

Quote: Originally posted by peach

Looks like you have sodium there. Nightinhawk, a guy on youtube who's fireworks cracky, has had a lot of luck with the NaOH / Mg thermite style pot method.

Quote: Originally posted by peach

I seriously think you should upgrade to stainless.

Quote: Originally posted by peach

A fairly obvious warning that I doubt you need, but be careful adding water from something like a cup or watering can. I've seen one guy do the same in one of these videos and the sodium spat back at him, and got him. If you suddenly make a break through, there could be a lump of it trapped in the tube, which may then explode when the watering can method is applied. My own silly story along those lines... I was melting lead water mains pipe in a pan buried in a fire. I knew there was water still on it because I could hear the violent boiling as I added them and they melted.

Try asking at the garages who do exhaust repairs. Some of them may be able to get stainless for fancy manifolds. I saw the guys making one at a metal fabrication place I did my work experience at in my teens, and their primary product was oil storage tanks for industrial heaters, ladders and beer keg carts.

Provided the wall thickness of the stainless is low, it shouldn't need heating. Swagelock is high purity stainless, and can be bent quite easily into complex tubing arrays. The Kurt ?Schreckling? guy who wrote "How to build gas turbine" bends the blades on the Inconel turbine blank with a little tool that looks exactly like a tap & handle, but with a slot in the end for the blade rather than a screw thread.

Hottest thing I've melted and cast? Aluminium. I was originally going for iron but then the garage needed knocking down and rebuilding from the foundations up.

Still got the iron contact capable refractory though, so it's probably in the works. The only reason I'd be interested in iron and those temperatures is a bit of artistic casting and machine tools. But the latter requires specific control of things like the carbon and the way it comes out on cooling down to produce a casting that isn't a pile of rubbish. As you probably know, there are many, many different cast iron structures in terms of the form the carbon deposits in. The right ones last forever, the wrong ones fracture on cooling.

[Edited on 2-10-2010 by peach]

Quote: Originally posted by metalresearcher

EDIT: I just found by Google an interesting article on tube bending:

Quote: Originally posted by metalresearcher

The problem when bending the tubes is that they flatten or get very kinky at the bend location. A plumber's pipe bender (local hardware shop $50) can resolve this problem but the radius is too large to fit the U in a furnace. EDIT: I just found by Google an interesting article on tube bending: http://www.hinesbending.com/BASICTUBEBENDINGGUIDE.pdf [Edited on 2010-10-2 by metalresearcher]

Yep, I know of the sand trick also.

Plumbers use a big spring that goes in the pipe and does a similar thing, stops it kinking in on it's self. The sand works better because it's finer and makes more contact, so it spreads the load and stops it collecting in points as wrinkles and kinks.

They use ice for bending the pipes on brass instruments. Fill with water, freeze, bend, let it melt out, for a super smooth wrinkle free result.

To expand the tubes to have them tightly mate with each other for joining, they push a slightly too large BB into the pipe, then force it through by pushing slightly smaller ones in behind it. The big one, obviously, stretches the pipe.

Plumbers have expanding hand tools that push into the end of the pipe, the grips are squeezed and a reverse collet type thingymehjiggy opens the pipe a bit for soldering. Saves buying more preformed joints and cuts down the number of joints. The fewer joints you have, the quicker the work gets finished....

It's possible squirty expanding foam may work as a replacement for ice, but it'll be more prone to collapse I expect. And it'll be a bitch to clean out by comparison.

[Edited on 2-10-2010 by peach]

Quote: Originally posted by Rogeryermaw

there is also a spreader tool that a/c guys use that looks like a series of progressively larger cones stacked on top of each other

I've got a Ridgid one, tool #562 for 1/4 ID tubing. Here a link to Google Products for one; photo from their site. The smallest diameter goes inside the tubing, the second one is the expanded diameter, the third one acts as a stop to keep it from getting too far down the tube. They're a standard tool for mating coolant lines to be brazed.

Thanks for all tips ! Ialready bent a steel pipe with sand and with success.
But I am looking around where I can get SS tubes as this is better. I also need them for other (non-chemistry) purposes.
I tried another approach with the steel tube: put it into a steel container filled with sand. This enables more evenly distribution of the heat over the vessel as there is no direct contact with the gas flames.
After 10 minutes of heavy bubbling of the oil the bubbling suddenly stopped, but I did not see Na colored flames or fumes coming from the sandbox.
The result afterwards was a little bit of Na metal in the tube.
The sand stops the leaking if there is a leak.
But I won't do this experiment again untilI have SS tubes.

EDIT: And I am thinking about using the same fine sand for capturing the Na and eliminating the stinking, polluting and flammable oil.

<hr />
Here a top view of the tube vessel in the sandbox after the session.



<hr />
Here a view of the complete setup taken out of the furnace after the session.


[Edited on 2010-10-3 by metalresearcher]

Other way to collect Na metal

Now I was thinking about another approach: attaching a closed metal can on top of the retort with the only opening being a narrow collar stuffed with rockwool allowing the CO to escape (and flush the oxygen out of it) while the Na vapor condenses and freezes to the inner wall of the can. At the end of the process the can can be taken off and the Na metal scraped off the walls.

Any comments ?

I tried an electric furnace

Quote: Originally posted by metalresearcher

Here all my pics and test results of sodium making: http://www.metallab.net/Na.php Now I tried an electrical furnace (without actual reaction, just to test if it gets hot enough) see the page mentioned above under the heading 'electrical furnace'.

@Picene : No yield yet I am experimenting:

And here the so manyth episode:

I got the leaking issue under control now by putting the retort in a sand filled crucible to spread the heat evenly along the retort and to reduce the oxidizing due to the sand layer. Furthermore I used a 20mm steel pile rather than 15mm. I can got no Stainless yet :-(
As the Kanthal furnace has to be rewired with thicker wire to get more power (700-1000W instead of 500W) I made a completely new small furnace heated by a low flame propane (without extra air) and keep all openings closed (except the top exhaust hole) with refractory felt. The oil did not catch fire anymore and the process ran smoothly (45 minutes) with a retort temperature (pyrometer peeked into the sandbox) of 1150oC.

But there was NO SODIUM at alll

The inside of the retort tube was clean, and when I poured water into the cooled retort no hissing appeared (and did not leak from the bottom which is a lttle good news).
During the process I saw it bubbling .
Where is the sodium gone ? In previous attempts I did get sodium.

Here a picture of the setup running:

I performed a test with three reactants !

First attempt to electrolyze NaOH