Remelted dross.... What to do with it?

[Twmaster]

While fiddle farting around today I decided it would be a nice day to do some melting. I have a small amount of pewter to turn into ingots and some 'hillbilly gold' to alloy with some pure lead to make into my favorite boolit alloy.

So while gathering my tools I noticed my dross can was full and much of it looked metallic. Shook out as much of the sawdust as I could (I use sawdust for fluxing) and put all of the metal looking dross into the pot and melted it.

After waiting what seemed forever I finally got a fully melted pot with what looked like 40 pounds of flux on top....

After skimming and re-fluxing the metal looks great. Nice and shiny. I've poured and recovered what looks like 3 pounds of whatever that is. The Lyman mold filled out really nice and silky smooth.

So, after all that long-winded hoo-ha, my question....

What to do with it? What is the likely content? I'm figuring mostly lead with very high percentages of Tin and Antimony based on reading some other threads about melts and temps and mistakes I've been making.

Ideally I'd like to get this tested for content. Mostly just to satisfy that itch to understand things a bit better.

[JWFilips]

Well, it usually has a good bit of "tin" in it...Not sure if it is worth the trouble recovering it. I have 20 lbs of it !
May have to watch this thread

[Twmaster]

I got a full 4 cavity Lyman ingot mold full of this. Actual weight was 2 pounds 13 ounces. With the price of tin this may be worth the effort to recover.

[bangerjim]

That is true "mystrie metal"! Heaven knows what is in there. Definitely some Sn you did not get reduced back in probably. 3# is not really worth taking to a yard and have them x-ray it.

I would just add it back into my mix a bit at at time, not knowing what the stuff really is. I probably have 50# of the stuff lying around. It will be my "last ditch effort" casting metal when I run out of all the tons of know alloys I have.

banger

[osteodoc08]

Likely a high tin antimony lead. Tin and antimony oxidize and mixes with the crud and lead to form a dross. You've essentially remelt we and cleaned it.

If high tin and antimony, take a known metal
and cast a boolit. Take mystery metal and cast same boolit. Compare weight. If my suspicions are correct, your mystery metal should be a touch lighter in weight.

[Twmaster]

I'm sure it's lighter. The comparison with known alloy Lyman ingots makes it very clear these are much lighter.

As I said in my original post I'm confident this is high tin and antimonial lead based on mistakes Ive made in past casting sessions.

[JonB_in_Glencoe]

When I smelt my range scrap (I don't dig/sift dirt, I just pick up boolits from the berm after a rain), That is when I also recover my metalic dross from my casting setup.

It's much easier and quicker to just dump the metalic dross into a freshly fluxed batch of molten range scrap. After the metalic dross is molten---doesn't take long, then just flux and reduce with saw dust a couple times.

[KYCaster]

Why did you skim it off in the first place?

If it's metal and you're able to melt it now, you should have been able to leave it in the pot with the original melt.

This is the problem I have with saw dust for flux.....a lot of stuff can hide in it! When you skim off the saw dust, you also skim off small particles of metal suspended in the saw dust. It got trapped there while you were stirring the saw dust into the metal. Skim it off and some of the suspended metal runs to the bottom of the container before it cools, leaving some metal in the bottom of the container......but also leaving some suspended in the saw dust.

After stirring the flux into the metal you should have a VERY THIN layer of ASH left on top of the melt. ALL of the saw dust should be reduced to ASH. If you're skimming saw dust off, you're using too much saw dust.

If the "DROSS" that you're skimming off has any metallic particles in it, there's something wrong. Your flux should reduce all the oxides back into the metal and leave only the ash that remains after all the flux has been oxidized mixed with any undesirable dirt. If you're fluxing correctly and still have metallic residue in your dross, then your alloy contains some undesirable component (Zn, Cu, Bi, Fe, etc.) or your Pb, Sb, Sn is way out of balance.

Best use of the alloy you recovered is put it in your next melt and do a better job of fluxing.

Jerry

[1johnlb]

I just throw it back in the pot with my plinking rounds and cast, I don't care what it is as long as it shoots and that it does.

[Chill Wills]

What is the likely content? I'm figuring mostly lead with very high percentages of Tin and Antimony based on reading some other threads about melts and temps and mistakes I've been making.
Ideally I'd like to get this tested for content. Mostly just to satisfy that itch to understand things a bit better.

Great questions! I've had the same questions myself. These are the two steps you need to do for meaningful answers.

Know what alloy was in the pot(s) the dross came from. -Do you know its content? or was it a "mutt" alloy?
Have the sample you reduced tested. Preferable by a reliable outfit.

I have done this and I hope you do the same and let us know!

Chill Wills

[runfiverun]

I do pretty much the same as jon does.
I re-run all my scrapings and skimmings and oxidized gunk back through with my range scrap.
I may only recover 2 pounds of whatever it is I get, but with all the gunk in the range scrap that needs cleaned out anyway, it's no more or less work and it ain't really gonna change the whatever it is in there alloy.
plus I'm doing it in my larger smelting pot before it hits my casting pot.

[lightman]

I smelt/melt in a pot that holds 300-400# of melted lead. I would dump this mystery metal into my next batch of WW or range scrap and call it good. I have a dutch oven full of this junk right now, just not sure if its worth the effort. And then I think about stopping in a busy intersection to rescue a wheel weight!

[MrWolf]

When I smelt my range scrap (I don't dig/sift dirt, I just pick up boolits from the berm after a rain), That is when I also recover my metalic dross from my casting setup.

It's much easier and quicker to just dump the metalic dross into a freshly fluxed batch of molten range scrap. After the metalic dross is molten---doesn't take long, then just flux and reduce with saw dust a couple times.

Basically what I do. Just put it in my next batch and flux away.

[RogerDat]

I just throw the metal I sift out of from the skimming bucket into the next batch of WW's. Figure it came out of the last big batch so feeding into the next one it will all even out.

There have been a couple (or something like that) times when I was under temp or had other issues and ended up re-melting and feeding the skimmings back in so I could do a better job of fluxing. Do Overs Rule! Think I may have to add that to my signature.

[Twmaster]

Following up. A kind member of the forums was generous and offered to test a sample of my re-melted dross. This is the report from the XrF machine:

Pb = 45.5%
Sn = 47%
Sb = 6.5%
Cu = 0.94%

So basically I am going to treat this reclaimed dross like 50/50 solder with a nice little Antimony bump.

[Chill Wills]

Thanks for posting this info....
It would be interesting if you knew what the make up was of the alloy you were taking this out of.
If so, can you tell us?
I asked above but you may not know what it is ????

Also, about the contents of your dross can? did you just skim during casting or was this what came out after fluxing/reducing? Or both? You get the idea of what I am asking....

Thanks! Chill Wills

[jmort]

As to the wood shavings/dust, you have to reduce it to ash. Keep at it. Thanks for this thread and the work you put into it.

[gtgeorge]

Wow I saved all my dross from smelting and pot skims and found the hardness and weight to be about the same as a blend of what i had melted and used. I had almost 80#'s from the last few years. So far what I have cast with it and bullets weights are close to what I normally use for casting.

So was some or a lot of that dross from melting down pewter?

[clodhopper]

Wow! that stuff is tin rich! The amount of tin would vary with how the pot is skimmed, temp, time, tool, operator.
I put my skimmings in a spaghetti sauce can with some small holes punched in the bottom. punch the holes from the inside before filling the can with skimmings. The punch holes, bent down helps the molten metal flow out the bottom.
When the can gets full it goes inside the wood stove for a good heating in oxygen poor environment.
in the morning when the stove is cool, rummaging around in the ashes under the can yields a wonderful chunk of lead "art", you never know what it will look like.
This method lets me skim the smelting pot getting lots of stuff off the top with the knowledge that the alloy is easy to recover.
Faster getting range scrap melted and ingotized.

[kbstenberg]

+2 for all of the work.
CW your question is also imp. about sn type used.
Twmaster your finding on the alloy comp. is very interesting. Your finding reinforce my view of remelting all of my dross.
I always keep any dross that I skim from any melt also. But I will sift it through a fine strainer to eliminate as much charred material as possible before remelting
I also do the same with any splatters that fall on the floor when I cast.

[Jeff R]

This is a great thread. My dross was too heavy to throw away, so I refined it. The surface of the dross ingots have some sort of crystalline appearance, so I figured it was high in something. The BHN of the dross ingots is 8.

In the photo it is next to an ingot of Lyman #2. I'll just gradually add it to some pot.

129902 129903

Thanks for your thread.
Jeff


Rocketing towards 200 posts!

[62chevy]

This is a great thread. My dross was too heavy to throw away, so I refined it. The surface of the dross ingots have some sort of crystalline appearance, so I figured it was high in something. The BHN of the dross ingots is 8.

In the photo it is next to an ingot of Lyman #2. I'll just gradually add it to some pot.

129902 129903

Thanks for your thread.
Jeff


Rocketing towards 200 posts!

Looks like the ingots I got from jetsfan last year. I think it's the antimony in them anyways they make great boolits.

[Twmaster]

Yes the Anitmony in the alloy makes the surface look like that.

[Ballistics in Scotland]

There are two ways you can possibly return more lead to the metal on the first melt. Fluxing with rosin etc. may help, and so may pushing the dross below the surface with something as you stir. With luck only substances lighter than lead will come back to the top.

Those oxides, sulphates etc. are pretty nasty stuff. Pure metallic lead isn't as poisonous as all that, as witness the Civil War veterans who had minié bullets extracted in the twentieth century, when X-rays made it easier to judge if it was safe. But it is the salts that go for you most easily.

You can calculate the density of a metal by suspending it on something of negligible volume (e.g superglue it to a human hair) and suspend it inn water. The dry weight divided by the difference between dry and immersed weights, is the density in grammes per cubic centimeter. Pure lead has a density of 11.34, tin 7.365 and antimony 6.697.

If you have a lead plus one other element alloy, your calculation can be precise, but that is unlikely with mixed scrap, dross or wheelweights. You can still get a pretty good idea of what proportion of non-lead things you have.

[RogerDat]

If my skimming was really 100% ash I would expect it to weigh less than it does even though it does have whatever dirt was in the WW's it came from in it. Still certainly worth running through a second time to reclaim. Especially given the Sn/Sb ratios gunned in the OP sample.

Might have to try something like the can with holes punched in it. Seems like that might be more efficient than tossing "crud" into the next smelting batch to skim a second time.

[osteodoc08]

Following up. A kind member of the forums was generous and offered to test a sample of my re-melted dross. This is the report from the XrF machine:

Pb = 45.5%
Sn = 47%
Sb = 6.5%
Cu = 0.94%

So basically I am going to treat this reclaimed dross like 50/50 solder with a nice little Antimony bump.

I see my assumptions were spot on. This is why I always try to reclaim my dross! Beeswax from Randy will reduce that right back in.

[BrianL]

I have been saving my dross and throwing it back into the first smelting of a batch of ww.

[bangerjim]

I see my assumptions were spot on. This is why I always try to reclaim my dross! Beeswax from Randy will reduce that right back in.

The %'s he came up with tend to indicate he was remelting lots of some kind of Babbitt. No all dross will contain those high levels of Sn. Sb and especially Cu....if you flux correctly 3X in your re-melting pots. If you are doing only COWW's you may have a little bit of Sn and Sb, but I would not suspect in those high levels! COWW's only have 0.5% Sn to start with!

Recycling dross is a peronal choice. I many times just throw it in the trash if the weight is not very high....meaning there is very little metal in there.....as it shoud be. If there is weight to the stuff, I throw in a can and mess with it later when I get about 15-20# of it.

banger

[gtgeorge]

The %'s he came up with tend to indicate he was remelting lots of some kind of Babbitt. No all dross will contain those high levels of Sn. Sb and especially Cu....if you flux correctly 3X in your re-melting pots. If you are doing only COWW's you may have a little bit of Sn and Sb, but I would not suspect in those high levels! COWW's only have 0.5% Sn to start with!

Recycling dross is a peronal choice. I many times just throw it in the trash if the weight is not very high....meaning there is very little metal in there.....as it shoud be. If there is weight to the stuff, I throw in a can and mess with it later when I get about 15-20# of it.

banger
Exactly what I was saying earlier with a very large amount of dross from melting range scrap, WW and a lot of 2-2-96 and a little mono and linotype. The weight of the bullets cast with this is the same as casting with the 2-2-96. I would gladly send some to someone if they want to analyze it.

BTW it is nowhere as clean as I would hope as I am sure it has contaminants in it. Not sure with our "home" fluxing will clean it up as nice as what I buy from a foundry. But then again I never saw wheel weights etc clean up that well either.