Zinc Removal with Steam and Flirting with Tinsel Fairy

[wimms]

Some time ago I had zinc in some of my melt. It came from range scrap, muriatic acid test was positive. I don't know how much but it was giving me hard time filling out my mold. So out of curiosity I got researching of ways to remove zinc at home relatively safely.

Sulfur doesn't sound nice, copper sulfide doesn't either. Besides it replaces zinc and Cu stays behind. It does dissolve in lead alloy to some degree and impacts mold fillout too. It also removes tin.

There is a process of lead desilverization with zinc where they intentionally add zinc to lead melt to extract the silver. Zinc preferentially alloys with silver and this alloy has higher melting point. This sounds promising as we could intentionally add silver by using silver containing solder in hopes to bring up both silver and zinc. But it has limit of applicability as zinc combines with silver only after zinc content in the melt is above 0.8%, meaning that this 0.8% of zinc needs to be removed later by other means.

Zinc vacuum vaporization that is industrially used for final zinc removal is out of reach for home setup.

I investigated molten salts on top of the melt hoping to find some salt compound that selectively reacts with zinc. There are some, but the temperatures needed go above 600C (1100F) and that seems too high for a steel pot that would be quickly corroded by molten salts. Besides there was chloride gas expected.

I investigated molten salt electrolysis at 400C (750F) where cathode would be solid zinc plate, anode would be the melt and molten salt would be the electrolyte. Seems promising but again some nasty gases are expected, and pot corrosion.

Caustics (Sodium hydroxide, NaOH) can be used to remove zinc, but it is not very active and leaves some sodium in the lead. I also don't fancy working with the most dangerous caustic when it is heated up to molten lead temps. Besides caustic also removes antimony.

I found that Zn reacts with phenols. C6H5OH + Zn → C6H6 + ZnO which is metane gas and zinc oxide. Where do you get phenols and how you introduce it into the melt? Well, I immediately thought that thermal pyrolysis of wood could be source of phenols, and it is. So what, cut a nugget off an aspen log, attach it to a steel paint stirrer, drown it into the melt and let it bubble while vigorously stirring with your power tool? Could be it, but there is lots of other **** in the products of pyrolysis that all tend to remain in the melt as impurities. Actually some of polymers like POM (plastic) are even cleaner than wood during pyrolysis, but I didn't really want to go there.

What really caught my eye was a process of solar hydrogen generation cycle that uses zinc oxide as a carrier of energy. It uses concentrated solar power to decompose ZnO at 1200C (2200F) into Zn and O2, after that Zn is delivered to reactor where it is mixed with superheated water steam to enable reaction Zn + H2O -> ZnO + H2.

https://en.wikipedia.org/wiki/Zinc%E2%80%93zinc_oxide_cycle

I researched on steam reaction with metals and turns out that steam reacts with only metals higher than hydrogen on the reactivity series.
"Metals such as Mg, Al, Zn and Fe react with steam when red hot. Tin and lead react with superheated steam with great difficulty. Copper, Mercury, silver and gold do not react with water or steam at all.

Only metals which are above hydrogen in the reactivity series displace hydrogen from water or steam. The reactions of metals with water are redox reactions".

https://secondaryscience4all.files.wordpress.com/2014/07/v3reactivity-series-of-metals.png

By introducing steam into the melt we are doing redox reaction of water by using for that purpose the very catalysts we consider to be impurities of the melt. A redox reaction that acts as a flux. Brilliant! And it's selective.

Apparently this method of reacting zinc with steam is known in metallurgy already since at least 19th century, so its nothing new. Some industrial processes have even been that daring that they introduce liquid water into the bottom of the kettle in carefully controlled doses. It might be even possible at home, but only for the most daring.

So how could we introduce steam safely into the melt? It is very important that the steam is absolutely dry - which means superheated with a safe margin. Any water steam above 200C (400F) is dry. At 450C (842F) it is already suitable for reaction. Below that it reacts with zinc very slowly.

I had an idea that the simplest way to generate superheated steam at home is to take a pressure cooker, attach a small diameter copper tube (like brake line tubing) to the cooker (new entry, preserving safety and pressure control valve), bend it into a spiral heat exchanger and let the wet steam go through it. Then use gas burner to heat up the copper heat exchanger so that the steam temperature is raised to above 400C (750F). It becomes dry, pure H2O steam.

Now if the end of that copper tube is also bent into a spiral with a deadend and steam escape vents facing down, and this spiral is drowned into the melt, pressure cooker generated pressure is enough for this steam to displace inrushing lead and push the steam bubbles out into the melt. Stirring with plain steel paint stirrer above the bubbles creates enough reaction sites that over time all zinc should get reacted into ZnO and float on top of the melt as white powder. Hydrogen gas generated could be controllably burned without letting it escape into environment and causing potentially hazardous concentrations.

Steam seems to be the cleanest possible way to remove zinc and many other impurities. It removes Mg, Al, Fe, Ca, Carbon (char, soot), but does not react with tin, lead, antimony, copper.

The safety warning - we are intentionally introducing WATER into the bottom of the melt. If anything goes wrong with the steam superheater and wet vapor gets into the melt, the tinsel fairy might say hi in unforgettable manner. I think it is not hard to ensure water get superheated before entering the melt by having some of coil length submerged into the melt acting as heat exchanger before steam reaches the vents.

I haven't tried this process yet, but I'm really itching.
Thoughts? Has anyone here tried using steam before?

[OS OK]

So how could we introduce steam safely into the melt?

I haven't a clue, have worked around steam my whole career and it's always associated with condensation...whatever you do...be sure to make a video, this is going to be epic!

[DougGuy]

I think you be wise to do this in a closed vessel from a safe distance no?

[Smoke4320]

hey Ma watch this :) :)

[dragon813gt]

The copper method is the best one available for the home caster. While there are issues w/ it the alloy at the end has useful properties. Adding tin back in is very easy. W/ the cost of lead alloys I would just toss the contaminated lead and start w/ new alloy. But my time is more valuable than money.

[JimB..]

I suggest that if you run your copper tubing around the inside wall of your pot, maybe a couple layers, so that there is 3’ or so of tubing in the melt that your risk of condensation will be low. Maybe wrap the exposed copper tubing in nichrome wire as a heat source.

Would have to go find a reference to calculate how much pressure will be required to inject steam into the bottom of 10cm of lead.

Cameras must be running for this!

[wimms]

I haven't a clue, have worked around steam my whole career and it's always associated with condensation...whatever you do...be sure to make a video, this is going to be epic!

Tell me more. What kind of steam, at what temperatures, what causes the condensation in real life?

[wimms]

I suggest that if you run your copper tubing around the inside wall of your pot, maybe a couple layers, so that there is 3’ or so of tubing in the melt that your risk of condensation will be low. Maybe wrap the exposed copper tubing in nichrome wire as a heat source.
3 feet? Why do you think so much is necessary? I'd think 1-2 rings around the pot would suffice. Surely wet steam from cooker must be first preheated, then can be delivered to the pot with insulated tubing, perhaps it makes sense to have a thermometer to check the temp before submerging the pot coil, and if the tubing is small enough, heat exchange is fast. Some kind of steam delivery rate valve is necessary perhaps.



Would have to go find a reference to calculate how much pressure will be required to inject steam into the bottom of 10cm of lead.

This is simple. p = 0.0981 * h * SG where h is head(m) and SG is specific gravity. For lead, SG=11 thus
p = 0.0981 * 0.1 * 11 = 0.11 bar above atmospheric pressure. Pressure cookers work at 1-1.2 bar.



Cameras must be running for this!
Thats for sure :)

[vzerone]

Condensation, when speaking about steam, is when the steam returns to a low enough temperature to turn it back into water. When you boil water in a tea kettle and the whistle starts blowing on the spout you see, (what most peopel call steam) escaping from the spout. That's not steam, that's condensation as the air around the pot has cooled the steam enough to begin to turn into water. That invisible space you see (which is very short) from the tip of the spout to that condensation vapor is "steam".

Why not just shoot your zinc ladened alloy if it cast good? Many here do.

[dragon813gt]

at what temperatures, what causes the condensation in real life?

It's not just temperature. There's a pressure temperature relationship. Read this if you want to know more specifics: http://www.wermac.org/steam/steam_part3.html

[vzerone]

It's not just temperature. There's a pressure temperature relationship. Read this if you want to know more specifics: http://www.wermac.org/steam/steam_part3.html

As pressure goes up temperature goes up. Exact opposite happens as pressure goes down, to a vacuum even. This vacuum is why nuke subs have a steam bubble (and noise) problem with their screws (propellers). Yes it's hard to believe being deep in the ocean and steam is forming on the back side of their screw and the noise is a major concern for running silent.

[wimms]

Condensation, when speaking about steam, is when the steam returns to a low enough temperature to turn it back into water. When you boil water in a tea kettle and the whistle starts blowing on the spout you see, (what most peopel call steam) escaping from the spout. That's not steam, that's condensation as the air around the pot has cooled the steam enough to begin to turn into water. That invisible space you see (which is very short) from the tip of the spout to that condensation vapor is "steam".
That's trivial, I don't think that's what OS OK meant. I think he's been working with closed steam delivery systems where condensation is meant to be avoided, but still happens. Steam in closed systems is tricky, as its condensation point is dependent on pressure and temp, and condensation can cause drastic changes in pressure. So professional insight is welcome.



Why not just shoot your zinc ladened alloy if it cast good? Many here do.
I don't need it. I scrapped my batch. It's just interesting refining method that can go beyond just zinc.

[Boolit_Head]

Ahhh just after they turn on the video ask someone to hold your beer...

[OS OK]

Tell me more. What kind of steam, at what temperatures, what causes the condensation in real life?

When the steam, low pressure steam comes out of the boiler's interior it is pure vapor, heat and pressure but it has to be conveyed to the work point in the system...it is in the transfer of steam to that point where it starts to condense as it looses temperature. They place water traps in front of pressure vessels where the steam is used for heat transfer, say to a web of paper in making corrugated board (boxboard) but the steam looses temperature in the transfer and always makes condensate on both sides of the trap. You can't use steam without making condensate and in your application it's going to go right back into steam in the Pb pot...then blam!

Temps? If I remember correctly it was at 275*F.

EDIT: Something else that just occurred to me is that when you get hit by steam, it'll cook you before you can react to get away from it. Steam is explosive when it ruptures a pipe or vessel into the atmosphere and under pressure it will cut like a razor as it cooks you. I've always been wary about working around steam, I've seen couplings blow apart where the piping is connected to a rotating vessel...it's unnerving and sounds like a jet engine...makes me cringe!
I wouldn't mess with this idea...

[vzerone]

If you look at steam turbine engines the rotor are a series of small rotors going up to large rotors. High pressure steam ( preferrably super heated steam) acts upon the small rotor first because it's at fullest power. As it passes through that rotor it loses some of it's power (think heat and pressure) so the next rotor is larger so it captures more of weakened steam, and so forth till the last largest rotor and then through the exhaust.

You never want to check for a steam leak with you hand, not even on low pressure saturated steam. Heard of a fellow checking for a steam leak on a super heated steamline and he fell to the floor in anguish. The steam cut his hand off at the wrist and it was just a pin hole leak.

Another dangerous concern of even minute drops of condensate are vacuum towers used in all sort of indrustrial applications from chemical plants to oil refineriers. They blow up violently when they get a drop of water in them.

I concur with OS OK I wouldn't mess with that idea.

[vzerone]

207142

[Silvercreek Farmer]

Dude, how much zinced lead do you have? My scrapyard will "trade" for a $.15/lb haircut.

[wimms]

When the steam, low pressure steam comes out of the boiler's interior it is pure vapor, heat and pressure but it has to be conveyed to the work point in the system...it is in the transfer of steam to that point where it starts to condense as it looses temperature. They place water traps in front of pressure vessels where the steam is used for heat transfer, say to a web of paper in making corrugated board (boxboard) but the steam looses temperature in the transfer and always makes condensate on both sides of the trap. You can't use steam without making condensate and in your application it's going to go right back into steam in the Pb pot...then blam!

Temps? If I remember correctly it was at 275*F.

I see. You probably work with steam that is used for heat transfer. It has to be wet or saturated steam for efficient heat transfer at destination through condensation. 275F seems to support that.

Pressure cooker provides wet steam and is not suitable for delivering directly into the melt, thats why I envision superheater, its purpose is to raise the temp of the steam to 400C (750F) at which point there is no chance that there is any condensate possible. Superheated steam has drastically lower heat transfer and we do not use very long piping, heat of the melt also only increases the temp of the steam, thus the conditions are rather different.

We won't use the steam for heat transfer. We'd want to make sure that superheated steam temp does not drop anywhere near hte saturation point before entering the melt and we are golden.

Just to make sure, superheated steam is abit different animal than saturated steam. I believe you know that and just missed my superheater on the way to the pot.



EDIT: Something else that just occurred to me is that when you get hit by steam, it'll cook you before you can react to get away from it. Steam is explosive when it ruptures a pipe or vessel into the atmosphere and under pressure it will cut like a razor as it cooks you. I've always been wary about working around steam, I've seen couplings blow apart where the piping is connected to a rotating vessel...it's unnerving and sounds like a jet engine...makes me cringe!
I wouldn't mess with this idea...
Fair warning. But we'd not need high pressures, we'd work with around 1 bar steam only as defined by pressure cooker's pressure regulating valve. This is rather tame. Though it's still a valid warning that steam leaks shouldn't be searched by naked hands, much like you shouldn't touch liquid lead to test if its warm enough. Pipes should have protective covers, insulation at least. That would dissipate any razor sharp steam jets.

[wimms]

If you look at steam turbine engines the rotor are a series of small rotors going up to large rotors. High pressure steam ( preferrably super heated steam) acts upon the small rotor first because it's at fullest power.

I concur with OS OK I wouldn't mess with that idea.

Guys, you are slightly overreacting. Please consider that proposed conditions are very different from typical industrial usage of steam.

Steam is hot. Right.
High pressure steam is dangerous. Right.
Wet steam says hello to tinsel fairy. Right.
Superheated steam at high pressure is extremely dangerous. Right.
Superheated steam at near atmospheric pressure is safe in the melt. It's just hot. But what's new in smelting?

We can arrange for rather safe application of steam for our usage.

[OS OK]

OK...sounds like you have yourself convinced that you can pull this off...just remember to video it...I wanna see what you look like 'before & after'...


:bigsmyl2:

"Hold my beer...watch this!"

[wimms]

OK...sounds like you have yourself convinced that you can pull this off...just remember to video it...I wanna see what you look like 'before & after'...

I believe so yes. But I take your input seriously. Why do you think it will blow up?

[JimB..]

3 feet? Why do you think so much is necessary? I'd think 1-2 rings around the pot would suffice.

This is simple. p = 0.0981 * h * SG where h is head(m) and SG is specific gravity. For lead, SG=11 thus
p = 0.0981 * 0.1 * 11 = 0.11 bar above atmospheric pressure. Pressure cookers work at 1-1.2 bar.



3’ was a swag at what a full lining of the pot would be, no real reason but more can’t hurt I don’t think.

Pressure is fluid density times depth times gravity, so
11 gm/cm3 x 10cm x 980cm/sec2 = 107,800 gm/cm2
Or 100bar

Although my units seem to be a mess so maybe I’m wrong. Looks like you and I moved the decimal in different directions converting gravity from meters per sec sq to cams per sec sq.

[popper]

You test turbine input (live) steam with a LARGE cardboard sheet.

[JimB..]

I am very concerned about pressure at the bottom of the pot. It will not be possible to keep the steam dry if the pressure is too high. Of course you could inject it just below or even at the surface. Slower effect, but perhaps safer.

[wimms]

Pressure is fluid density times depth times gravity, so
11 gm/cm3 x 10cm x 980cm/sec2 = 107,800 gm/cm2
Or 100bar
11 g/cm^3 x 10cm x 980cm/sec^2 to bar (http://www.google.com/search?safe=off&dcr=0&q=11+g%2Fcm^3+x+10cm+x+980cm%2Fsec^2+to+bar)

0.1078 bar

[OS OK]

I believe so yes. But I take your input seriously. Why do you think it will blow up?

Because when the steam looses temperature it condenses. Also, when first starting up the process, steam will loose temperature until all the tubing involved is as hot or hotter than the steam within...the result is condensation in the steam delivery line and eventually it's going to find it's way into the melt. Condensate doesn't necessarily mean droplets of H2O...it begins as superheated H2O and deposits like a film along the interior of the piping and accumulates into droplets eventually...it's appearance is like a shiny Clear Coat PC...Steam piping is a one way system and the steam will push the accumulating film/condensate with it.
I just can't see how you can avoid the condensate...condensate is H2O & that will return to steam in the melt...can't see how you can avoid it.

Possibly if you were to bring the steam system up to temp before the melt is started in the pot and maintain the steam, it seems that the steam in direct contact with the melt would be encouraged to remain as steam because of the Pb temp...I really dunnoh? This is the first I've ever heard of such a process...I'm hung up on the physics of condensate being introduced into the melt.

If I were looking at 1,000 lbs. or so of Pb I could recover then that would be tempting but I would for sure talk to someone who has done it before...all of us keyboard jockeys around here will only help you get burned or worse!

[lightman]

While the science behind this is interesting, I believe I would either dilute the contaminated alloy until it would cast well or just scrap it.

[MaryB]

The above! Add more alloy until the zinc is below 1%

[vzerone]

The above! Add more alloy until the zinc is below 1%

That's what I said earlier. A little bit of zinc doesn't hurt, other then it may make the alloy a little harder.

[JimB..]

11 g/cm^3 x 10cm x 980cm/sec^2 to bar (http://www.google.com/search?safe=off&dcr=0&q=11+g%2Fcm^3+x+10cm+x+980cm%2Fsec^2+to+bar)

0.1078 bar

107,800 g/cm^2 x 0.000980665 = 105.7bar

This agrees with the website https://www.convertunits.com/from/g/cm%5E2/to/bar

I’m happy to understand where I’m wrong, but our math is in agreement until the conversion to bar which is a black box.

[OldBearHair]

Ten inch sections of Stainless Steel wire .020 dia. packed into the 3/16 brake line until no more will fit in and then coiled to fit the application might help with delivering the needed amount of steam to the bottom of the mix. Or however long the submerged coiled tubing is would work instead of the 10" sections. SS fishing leader line can be used.

[OldBearHair]

Ten inch sections of Stainless Steel wire .020 dia. packed into the 3/16 brake line until no more will fit in and then coiled to fit the application might help with delivering the needed amount of steam to the bottom of the mix. Or cut wires to however long the submerged coiled tubing is would work instead of the 10" sections. SS fishing leader line can be used.

[runfiverun]

the melted alloy alone would provide enough heat to insure the steam stays steam.
[that extreme heat is what causes the tinsel fairy to visit]
it's between the pot and the coils I would be most concerned about condensation occurring.

I wonder if you couldn't just pull zinc out by boiling water on top of the alloy.
it would be a fairly tedious process of stir boil stir boil skim stir boil.

[vzerone]

the melted alloy alone would provide enough heat to insure the steam stays steam.
[that extreme heat is what causes the tinsel fairy to visit]
it's between the pot and the coils I would be most concerned about condensation occurring.

I wonder if you couldn't just pull zinc out by boiling water on top of the alloy.
it would be a fairly tedious process of stir boil stir boil skim stir boil.

I was waiting to see if anyone caught that the heat of alloy would insure the steam stayed superheated steam. By golly you knew runfiverun!!

[john.k]

Ay caramba.Have you met the grim reaper,yet?This is the craziest thing I have ever read on a forum,any forum.And its so easy to do.What could possibly go wrong?

[rondog]

Wow, there's NWIH I'd go through all that expense and hassle! I'd just scrap it and buy fresh alloy from Rotometals.

[wimms]

107,800 g/cm^2 x 0.000980665 = 105.7bar

This agrees with the website https://www.convertunits.com/from/g/cm%5E2/to/bar

I’m happy to understand where I’m wrong, but our math is in agreement until the conversion to bar which is a black box.
Your mistake is in units. Pressure is in units of force per area, N/m^2, and your final units is g/(cm*s^2) not g/(cm^2)

Simpler approach: you know that 9.8m of water head is 1 bar pressure. Lead is 11 times more dense, thus 9.8/11=0.9m of lead head is 1bar. 0.1m of lead is 0.1 bar.

[JimB..]

Your mistake is in units. Pressure is in units of force per area, N/m^2, and your final units is g/(cm*s^2) not g/(cm^2)

Simpler approach: you know that 9.8m of water head is 1 bar pressure. Lead is 11 times more dense, thus 9.8/11=0.9m of lead head is 1bar. 0.1m of lead is 0.1 bar.

Thanks, that makes sense.

[wimms]

Because when the steam looses temperature it condenses. Also, when first starting up the process, steam will loose temperature until all the tubing involved is as hot or hotter than the steam within...the result is condensation in the steam delivery line and eventually it's going to find it's way into the melt. Condensate doesn't necessarily mean droplets of H2O...it begins as superheated H2O and deposits like a film along the interior of the piping and accumulates into droplets eventually...it's appearance is like a shiny Clear Coat PC...Steam piping is a one way system and the steam will push the accumulating film/condensate with it.
I just can't see how you can avoid the condensate...condensate is H2O & that will return to steam in the melt...can't see how you can avoid it.
Check out properties of superheated steam. Condensate can occur only when steam is cooled down to temp of saturation, which is around 130C at 2bar abs pressure. When you add heat to the steam, it has to be released before it can fall down to that. And we do add lots of heat to raise it to 400C. Sure, the whole tubing must be at higher temp than 130C for condensate to not occur, by a safe margin, but it is doable, and superheated steam will do it.


Possibly if you were to bring the steam system up to temp before the melt is started in the pot and maintain the steam, it seems that the steam in direct contact with the melt would be encouraged to remain as steam because of the Pb temp...I really dunnoh?

But of course, you startup the steam and bring it to working temperature before you submerge the coil into the melt, or use some valve to purge the tubing before redirecting steam into the melt. Superheated steam will dry out any moisture in the tubing and any little that gets carried along is turned into steam by the tube section that is in the melt and at the melt temperature.


This is the first I've ever heard of such a process...I'm hung up on the physics of condensate being introduced into the melt.

This is actually quite interesting. This process of using steam for lead refining was first used Cordurié in 1867 and has been used in lead industry for over 100 years, yet it is still quite difficult to find description of it on internet. But not one book on lead metallurgy exists that doesn't mention it.

It exists, it's not my invention by any stretch, I just try to apply it on a small scale.


If I were looking at 1,000 lbs. or so of Pb I could recover then that would be tempting but I would for sure talk to someone who has done it before...all of us keyboard jockeys around here will only help you get burned or worse!

I'm aware of the dangers as should anyone be who wants to try it.

I'm not even so much interested in removing zinc. This process is more than just for zinc, it removes many impurities, fluxes, stirrs, and is completely clean. In industry they don't even use mechanical stirring anymore, they use steam stirring.

It is easy to add CO2 to the steam, or even by adding charcoal on the path of the superheated steam to generate CO inside the tubing which works as lead and tin oxide reducer, and can be burned on the surface of the melt. Heck, you could even inject propane into the pressure cooker. It will self-ignite after coming out of the melt, leave some carbon and reduce surface oxides. It can't burn inside the melt as there is insufficient oxygen there. Pure steam removes carbon by gasification of it into CO2.

It looks like it is possible to do lead refining without needing any of the traditional fluxes that burn, stink and leave ash behind, using only gaseous matter. It's fascinating.

And I am well aware how crazy it sounds. But we are all crazy here right? It's just a new level of crazy I guess..

I'm telling you, seriously, some refineries don't even bother with steam, they route tap water under the kettle, use tap water pressure to force water into the melt and let the melt do all the steam generation. Boiler is tubing inside the melt and uses the heat of the melt to generate steam before it is released into it. Kettle loads in tens of tons at a time..

[OS OK]

Like I said before...make a video. Not so much now for the explosion but I'd just like to see the process.

Have you thought about how to keep the splatter down to a minimum? You know though...the superheated steam shouldn't expand any more physically when it hits the bottom of the pot so...it oughta just bubble in the pot like boiling water bubbles?

right...?

[john.k]

There are any number of industrial processes that work perfectly every day,but to attempt them in a Lee 20lb pot and a pressure cooker would be more than a bit risky.

[wimms]

There are any number of industrial processes that work perfectly every day,but to attempt them in a Lee 20lb pot and a pressure cooker would be more than a bit risky.

Oh no, this is not for a lee pot. It's a smelting job outside and with propane burners.

[wimms]

Like I said before...make a video. Not so much now for the explosion but I'd just like to see the process.
I will. But this will have to wait for spring. It's cold winter season here.


Have you thought about how to keep the splatter down to a minimum? You know though...the superheated steam shouldn't expand any more physically when it hits the bottom of the pot so...it oughta just bubble in the pot like boiling water bubbles?

right...?
Yeah, I expect it to look like boiling water. My plan is to make orifices small so that they work as restrictors. The steam would probably still expand as I don't think I can control the superheater output temperature very accurately, and the melt temp could be anywhere between 500-800C. That's really my main concern - I need high btu heater to heat up steam fast, and have to make sure I do not overheat the copper tubing vs underheat the steam. In addition to that pressure cooker regulating valve is pulsating type thus the steam pressure and flow will also be pulsating. I also need to find a way to regulate the steam flow rate. And, I'd need to rebuilt my smelting station before I dive in with those experiments.

[William Yanda]

In your op you specified "copper tubing like brake line" or words to that effect. Brake line is steel, and probably cheaper than copper. The trade-off is that it is more reactive with water and even more reactive at elevated temperatures. And there are always trade-offs.

[OS OK]

https://www.youtube.com/watch?v=6HhdkkdsvTM >An old film of lead mining in the US. Very interesting.

https://energy.gov/sites/prod/files/2014/05/f15/processcontrol.pdf > Starting on page 9 there is info in controlling steam...looks expensive.

[Bent Ramrod]

There are steam traps (actually condensate traps) that are used to keep steam lines dry.

All the ones I’ve seen are pretty good-sized, used on well insulated steam lines running from the boiler house to outbuildings. You’d have to consult a catalog to see if they make small ones.

They would trap the condensate and hold it until enough had built up to open a valve at the bottom, then the steam pressure would blow it out. When the trap was empty, the valve would seal again.

They saw hard service where I worked and were constantly sticking open and had to be maintained. But better than having condensate in the lines at the operating end.

[alamogunr]

I knew I should have paid more attention in beginning thermodynamics classes in college. I still wouldn't have been able to add anything intelligent to this conversation but I might have understood it better.

[wimms]

Brake line is steel, and probably cheaper than copper. The trade-off is that it is more reactive with water and even more reactive at elevated temperatures. And there are always trade-offs.
There are several types, steel, braided, copper, and copper-nickel. The latter one is best suited. We might use even plumbing copper tubing, but the brake line tubing has a kind of its own fittings universe that is convenient to use I hope.


There are steam traps (actually condensate traps) that are used to keep steam lines dry.

They saw hard service where I worked and were constantly sticking open and had to be maintained. But better than having condensate in the lines at the operating end.

The whole point of superheating is to 1) avoid the need for traps, and 2) prep the steam volumetric density so that it does not explosively expand inside the melt. Thus I want to preheat it up to at least 400C.

[gwpercle]

hey Ma watch this :) :)
I know what happens when you say that !

Please make a video of this.....it's going to be a humdinger !

[runfiverun]

about 15 seconds in.


https://www.youtube.com/watch?v=T5ghrpmZc5o

[McFred]

Wimms, I like the way you think. If you have mostly pure lead contaminated with zinc then you can heat the melt up to any temperature over a propane burner. Dribble distilled water via an IV bag on a stand, for example, through some copper "refrigeration tubing" or "capillary tubing" coiled up in the propane burner flame under the pot for a 'dry steam' source and rig a mechanical agitator and percolate the steam through to generate your zinc oxide for skimming. It'd be quite easy with some 20lb propane bottles cut open and organized to skim the impurities and later pour off the result. I wouldn't regulate the steam, just the flow rate of water into the capillary coil. Once the lead is up to temperature it shouldn't take much heat to keep it liquid, use the spare BTUs to boil the water instead. Think about how liquid-fuel rockets work: liquid fuel is evaporated in the exhaust before the gaseous fuel's injected into the jet nozzle...

I'm surprised that the other users are such closed-minded safety nazis that they can't conceive of a safe way to accomplish the goal. Shame on them for crapping on your proposal. I too want a video or a report on the success; not for an explosion.

Some people don't realize that the process is often as fun as the end result. I say go for it.

[OS OK]

So...now we are calling each other... 'NAZI's' ...that's a new low!

[McFred]

Sorry, what's the internet-lingo equivalent of someone putting down another person's idea for fear of injury? Mother hen? Nanny? Babysitter? OSHA rep? In my defense I did use a lower-case "n" for the nazi word. :)

[OS OK]

I'm glad you didn't mean it in a mean spirited way...but...I've heard that term applied to the Conservative Right for so long now that it just took me back hearing it come from within our brotherhood!

[runfiverun]

he I'm sure meant it more like grammar or spelling nazi.
it's more a grrr grmble thing than a pointing fingers hey look thing.

check out that video that I posted, it shows them doing exactly what is proposed here.

[john.k]

The video shows a common method of removing dross from a melt,by bubbling an inert gas thru,the bubbles carry the impurities to the surface for skimming.This method is commonly used prior to pouring aluminium alloys.A ceramic sponge disperses the gas,which is argon or helium.Bubbling steam is a bit different,in that a violent reaction may occur.Without elaborate precaution steam in a long tube will be accompanied by slugs of superheated water.Where is the tower,Bulgaria,Romania? dont seem to be any EPA or WHS.