Soften WW Lead?

[GBG]

Recently a batch of WWs we melted down for ingots were very dirty and rusty. Even after raking off the steel clips and repeated fluxing and skimming, the ingots still held enough debris to partially clog the bottom pour spout of our small casting pot when remelted for making buckshot.

On the next batch of dirty WWs melted for ingots, after repeated fluxing a good skim of slag would still rise to the top. Fearing more casting problems we increased the temperature and dipped pint sized ladels of lead up then poured it back into the pot mixing and aerating the melt. Each time this would bring more slag to the top.

Since the air bubbles seemed to be removing the impurities we tried something new. After adding lots of protective welder's clothing, we injected low pressure (

 

[Idaho Ron]

Here is my guess. I think you have some zinc mixed into your lead. Most WW's are either Steel or Zinc. You can still find some lead but that lead is going to be hard. If your lucky to find lead stick on's some of them are fairly soft.

Back to my thought. It takes a great deal of heat to melt zinc. Most of the time it will skim off as a WW but I have melted it into lead and it makes a mess of the lead for bullets. I used a small amount of lead to melt zinc to make sinkers. I am only guessing but I think the air cooled off the zinc enough to allow you to skim it off.

Did the dross look like oatmeal? Ron

 

[F.G. Ford]

Melting your lead to 1100 degrees is a hazardous situation.
Lead oxide fumes are dangerous, and can cause some serious health issues.
You will need a very good exhaust hood, or strong fan to keep lead fumes away from the operator.
Good Luck!
Fred

 

[GBG]

The wheel weights were salvaged from the ground under a rusted out barrel and were about 20-25 years old. Don't know how much zinc was in them back then. Also, the buckshot and balls weigh only a few grains less than pure lead the same size.

The dross was a silver-grey crystal like metal, heavier than aluminum but lighter than steel with rainbow colors reflected in skylight. It was brittle and cracked after bending when cooled.

The temperature at the bottom of the melt where the air was injected could have been higher than 1100, because the steel pot legs started to get soft and began deforming under the weight of the lead. Since the lead looked shiny and clean, we cut off the air injection and stopped blowing combustion air into the wood coals to let it cool down for casting ingots.

We always melt wheel weights outside on a breezy day and stay upwind while working.

 

[Idaho Ron]

The wheel weights were salvaged from the ground under a rusted out barrel and were about 20-25 years old. Don't know how much zinc was in them back then. Also, the buckshot and balls weigh only a few grains less than pure lead the same size.

The dross was a silver-grey crystal like metal, heavier than aluminum but lighter than steel with rainbow colors reflected in skylight. It was brittle and cracked after bending when cooled.

The temperature at the bottom of the melt where the air was injected could have been higher than 1100, because the steel pot legs started to get soft and began deforming under the weight of the lead. Since the lead looked shiny and clean, we cut off the air injection and stopped blowing combustion air into the wood coals to let it cool down for casting ingots.

We always melt wheel weights outside on a breezy day and stay upwind while working.

Since they are about 20 to 25 years old you won't have any zinc. Back that far they could be close to pure. Your weights confirm that.
The way your describing the dross sounds like zinc but I don't see how it could be that old.
You got me. I have poured a lot of lead but I have never done that kind of stuff before. Sounds interesting.
I got an offer for you. You can send me a small sample of the lead before you added the air and then another that you added air to. I will test them for hardness. Now you got me curious. Ron

 

[Bill Hall]

You got me too, and I am also curious. Anytime air comes into contact with molten lead, it forms lead oxide, which automatically floats to the top. I don't believe you are cleaning out impurities in the lead by injecting air, just creating more oxidized lead. Since it floats to the top and looks "cruddy", it's easy to think you're cleaning out bad stuff from the lead, but in actuality, you're merely creating it.

But, if you find that after your air treatment the balls seem softer, something must be going on there. It may be that you're jumping to conclusions, or your "testing" is off a bit (it happens). But if they are really softer, I'd sure like to know.

Why don't you take Ron up on his offer of testing the hardness. Maybe a good sampling of each of the balls, like 5 hard and 5 soft. This is how we learn new things :thumbsup: . Bill

 

[GBG]

Thanks Ron, I'd be glad to send you some. What size or shape do you need for a sample?

We've got some 1/2 or 1 pound ingots of the dirty lead and several 2-3 pound round 'corn muffins' of the air blasted lead. Also got both in various sizes of buckshot up to about .330" diameter, and can cast new balls from .440 up to .735".

If RBs won't work we've got bullet molds from .338" up to .54" plus 12 gauge slugs.

Just PT an address and I'll get them in the mail.

snowdragon, I'd wondered about lead oxide because the dross would keep forming a very thin layer when more air was added to the clean lead. I'm just familiar with the white powder oxide but couldn't tell if it was present. Everything scraped off looked the same as described above.

 

[Idaho Ron]

Thanks Ron, I'd be glad to send you some. What size or shape do you need for a sample?

We've got some 1/2 or 1 pound ingots of the dirty lead and several 2-3 pound round 'corn muffins' of the air blasted lead. Also got both in various sizes of buckshot up to about .330" diameter, and can cast new balls from .440 up to .735".

If RBs won't work we've got bullet molds from .338" up to .54" plus 12 gauge slugs.

Just PT an address and I'll get them in the mail.

I can measure anything that is less than 1" thick. The easiest and most accurate would be a bullet with two flat ends. I can do PRB's too no problem.
What ever is most convenient for you. 5 samples of each would give the best results 3 samples would work too. I have done this before for several guys. I have always said anyone on the forum that wants lead tested I would be glad to. I will send a PT. Ron

 

[target man]

when melting weel weight ,i realize ,the bottom of the lead in the melting pot
was more dense and heavier ,

i think i have read some where ,the purest leads was in the bottom ???

if the hot lead was not as much brew,,mixed before put in the mold,

it possible a same bullet weight heavier in a half portion ,,and that may affect the accuracy
during the flight to the target ,,


now i keep weelweigth for bird and buck shots,
and pure lead for bullets

target man

 

[Idaho Ron]

when melting weel weight ,i realize ,the bottom of the lead in the melting pot
was more dense and heavier ,

i think i have read some where ,the purest leads was in the bottom ???

if the hot lead was not as much brew,,mixed before put in the mold,

it possible a same bullet weight heavier in a half portion ,,and that may affect the accuracy
during the flight to the target ,,


now i keep weelweigth for bird and buck shots,
and pure lead for bullets

target man

Alloyed lead will not separate by skimming off. I do believe that if it is not stirred the bottom will be some what heavier. I alloy a slight amount to get "my" mix for conicals. I use a ladle to make sure I don't get any separation. I do believe that the difference will affect accuracy. Again that is why I use a ladle. Ron

 

[mazo kid]

My feeling is that you got lucky with your wheel weight alloy. Zinc melts about 790*F so if there were any zinc WWs, they were incorporated into the lead. When I am making ingots from WW, I keep the temp about 700* and the zinc ones float on top of the melt, making it easy to scoop them off the surface.

 

[GBG]

Thanks, that's good to know how to seperate them.
I learned a few handfuls of new WWs may have accidentally been thrown in the old pile since the last time casting ingots.
I'll keep the temp. low and pick out the zinc floaters until the top few inches of weights are removed from the bucket.

 

[russecv58]

its possible you may have softened it some. according to this

Pyrometallurgical Refining
Pyrometallurgical Refining is performed in liquid phase, which means that the crude Lead must be melted to temperatures from 327ºC (Lead fusion point) to 650ºC. As a general trend, the process is performed in batches of 20 to 200 tons, according to the refining plant capacity. The chemical concept behind the refining process is the addition of specific reagents to the molten Lead at proper temperatures. These reagents will then remove the unwanted metals in a specific order as they are added selectively.
Copper (Cu) is the first element to be removed with elementary Sulphur in a two phase procedure. In the first step, almost all copper is removed as a copper sulfide (CuS) skims when elementary Sulphur is added to the molten Lead at 450ºC. The second step is meant to remove all remaining copper by adding small amounts of elementary Sulphur to the molten Lead at 330ºC until no reaction takes place anymore. Tin (Sn) is next removed by either chlorine (Cl2) or ammonium chloride (NH4Cl) oxidation. The addition of chlorine to the molten Lead at 500ºC produces tin chloride (SnCl2) skims which are mechanically removed. Although this is the current method for tin removal, its inconvenient is the parallel removal of small amounts of antimony (Sb) and arsenic (As) by oxidation.
Arsenic (As) and antimony (Sb) are selectively removed by oxidation with either air enriched with oxygen (O2) or a mixture of sodium nitrate (NaNO3) and sodium hydroxide (NaOH). The temperature of the molten Lead is raised to 550ºC and a flow of O2 enriched air is bubbled into it. The reaction is extremely exothermic and the temperature easily reaches 650ºC. Those skims are a mixture of oxides (25% Sb, 10% As and 65% Pb).
Silver (Ag) come next and its removal is carried out by the Parkes Process, which makes use of the preferential solubility of silver in molten zinc (Zn) instead of molten Lead (Pb). Therefore, metallic zinc (Zn) is added to the molten Lead at 470ºC and the mix is allowed to cool to 325ºC. A silver ”“Lead zinc alloy separates and forms a crust on the surface. The crust is removed and the zinc separated from the silver by vacuum distillation. The crude silver is further refined using oxygen to produce fine silver. The excess of zinc is removed from the de-silvered Lead by vacuum distillation and then by Sodium hydroxide (NaOH).

 

[Idaho Ron]

I have the results of the hardness test. I will post in a separate thread. Ron

 

[Stumpkiller]

You have a home furnace that gets up to 1,200°F?

 

[GBG]

I don't know if it would be considered a furnace, perhaps more like an outdoor oven.

We stack fire bricks in a circle around the steel pot, and leave an opening at the bottom to feed in combustion air.
For fuel we use a combination of well dried hardwoods and when we want high temps we add dark, rosin rich, red pine heartwood. This is known locally as "rich pine". A few lumps of bituminous coal on top of the wood seems to helps too.

When a good bed of glowing coals form, a 100-120 psi air blast is directed against the inside wall of hot bricks and circles into the fire bed. This can bring steel to glowing red heat.

We had never heated lead to these temps before, and only tried this to see it could be cleaned.

 

[Marc Adamchek]

Well yeah, Cap Smacker, that's easy for YOU to say!

 

[David G]

:haha: I'd say that ought to clean it up! :thumbsup: