PDA

View Full Version : Zinc


parttime
December 15, 2009, 08:57 AM
I have yet to cast any rounds, so for just reading an trying to compile the neccesary items. I keep reading that if Zinc becomes mixed in with the alloy it is bad, bad, bad. Is there any way to remove the Zinc once it becomes part of the mixture?

Stick_man
December 15, 2009, 05:05 PM
If you do a search on zinc in this forum or others you will likely find several ways to remove zinc from a lead alloy. Some are expensive, some are dangerous, most probably don't even work.

If you have just a small batch of contaminated alloy, you might be able to add enough pure lead to dilute the zinc to the point of it no longer causing problems for casting. That should be somewhere around the <5% range by weight.

I recently read about somebody saying zinc can be used in casting, but you need to use a lot of heat and some special handling to get good mold fillout. It was also recommended to NOT use zinc contaminated bullets for hunting since they won't expand hardly at all. Never tried it, never seen it done, just passing along some information I read about it.

GP100man
December 16, 2009, 12:11 AM
To check for zinc put a drop of muretic acid on an ingot it will give a reaction !!!

To remove zinc it`s been said to flux with sulphur.

I have heated a melt hot 850f then let it cool no stirrin & skim the oatmeal off the top , this is at 600f the zinc floats then freezes .

Just stay on top of your smeltin procces & the zinc will float before it melts , go slow & skim em off!!

Hope this helps even if a little!!

parttime
December 16, 2009, 01:41 PM
I thank you for your responses. As soon as I get the hang of melting down w/w and other scrap, I'll try the smelting process that you discribed with the 15lbs or so of ingots that I was told had zinc in it.
Thanks again.

GP100man
December 17, 2009, 07:05 AM
Before trying to remove the zinc try a castin with it , it may cast fine if not then I would go another route!!

If it`ll cast ok I`d go with it !:):cool:

darkgael
December 17, 2009, 08:20 AM
It was also recommended to NOT use zinc contaminated bullets for hunting since they won't expand hardly at all.
I can believe that.
I know that zinc bullets don't even deform a whole lot when fired into a steel backstop at my indoor range. Had to stop using them.
Pete

snuffy
December 17, 2009, 02:33 PM
Over on the cast boolit forum, there was a guy that was going to try to separate zinc that had been alloyed into lead. The procedure was to heat a pot to just over the point that the lead would melt. Like GP100 says, it's right around 600 deg. The zinc will,(supposedly), separate and float to the top, to be skimmed off.

I don't think you will get all of it that way, but most will be gone. It's important to remember that zinc melts at 787 degrees. As long as your WW smelter is UNDER that temp, you will see the zinc WW floating along with the steel clips. Skim them out, you're in good shape then. That requires a thermometer, but you need one anyway, right?

spitpatch
December 19, 2009, 08:21 PM
Reading in some of my old Lyman reloading books- from the 40s & 50s, in the cast bullet section it states that 1 part zinc to 10,000 lead is no good.
Stay away from wheel weights that are squared on the ends, they are for mag wheels and contain zinc.

res45
December 29, 2009, 08:19 AM
A good pot thermometer is always a plus to keep a check on your alloy temp,Lead melts at 621 degrees Zinc at 787 degrees. As mentioned the Zinc weights will float to the top and you can skim them off. I've missed a few when culling out 5 gal. buckets full of WW,I've never had a problem with the alloy I found floater in. The key is keeping your temp right so they don't melt in.

http://www.rotometals.com/product-p/lead_thermometer.htm

45long
October 14, 2013, 03:11 AM
I got my WW lead too hot and made a lot of ingots.A whole lot of ingots:mad:

This is what I noticed about zinc in bullets. They don't like to expand when hitting wood targets ,so if they were to hit a deer their not going to expand either .

I have a couple bullet traps. One is just an angled 1" steel plate over sand. They stay intact when they hit that one . The other trap is a round tube type (deceleration trap) The bullets spin around until they loose velocity and fall into a bucket. When I shoot into that trap they just turn to dust.

I am going to keep this dust and try to extract the lead out of it by heating it to over 787 degrees and fluxing it with sulfur and letting it cool to just above the melting point of lead 621 degrees and skimming it off the top..I'll see if that works.

I'll post my results later..

maillemaker
October 16, 2013, 09:31 AM
I recently read about somebody saying zinc can be used in casting, but you need to use a lot of heat and some special handling to get good mold fillout. It was also recommended to NOT use zinc contaminated bullets for hunting since they won't expand hardly at all. Never tried it, never seen it done, just passing along some information I read about it.

I accidentally ordered zinc instead of lead once from Rotometals. I did not realize it and put it in my pot and melted it and poured it into my mold.

When I tried to shear the sprue, the zinc was so hard it buggered up the knife edge of the inlet hole.

So I think that we may be able to use zinc to make bullets (expansion properties aside), but it will require some changes to our bullet molds to do it.

Steve

F. Guffey
October 16, 2013, 11:36 AM
"If you have just a small batch of contaminated alloy, you might be able to add enough pure lead to dilute the zinc to the point of it no longer causing problems for casting. That should be somewhere around the <5% range by weight"

http://www.shootersforum.com/bullet-casting/42663-zinc-mixed-lead-2.html

http://www.thehighroad.org/archive/index.php/t-389772.html

5 pounds of zinc to 95 pounds of lead?

Then there is the 1 pound of zinc to 10.000 pounds of lead.

It is time to get R. Lee's book on modern reloading out, not necessary to read it, just get it out, Somewhere there is a comment that goes something like "If it has lead in it bullets can be made"

F. Guffey

totalloser
November 9, 2013, 08:34 PM
As I understand it, you CAN NOT skim it out once it's in. At all. All you can do is dilute it to the point of usability.

Zinc fully alloys with lead, so it will never separate out without a caustic chemical reaction. What does separate and float at the surface is tin, which will not truly alloy with lead. It forms an amalgam, which routinely separates out, but can be fluxed back in. This means if you are skimming the shiny top off, you are probably tossing your valuable tin.

With the Zinc melting at 787F, and the lead melting at 621F, it is possible, and relatively easy to melt the lead and scrape all the other junk off the top. But it has to be a slow melt since the base of the crucible or pot will be hotter than 621 to melt the lead, and in a fast melt it may be significantly higher. I use a wick type kerosene stove to temper my patience since it is so slow as to be almost impossible to overheat the initial WW smelt.

Also, Zinc will contaminate the melt *before* melting point but at a *very* low rate. Similar to tin mixing (449F) into lead. Tin will mix into lead at temperatures WELL below it's melting point. A technically inaccurate but very good illustrative description is melting away a lollipop in your mouth. (ERROR! Note below)

dahermit
November 9, 2013, 08:47 PM
Tin will mix into lead at temperatures WELL below it's melting point.With the melting point Lead at about 620 F. and Tin at about 430 F., that is a little hard to envision how that would work. If the lead is liquid, and you put in some Tin, of course it is going to melt and alloy with the Lead. A solid piece of tin is not going to alloy with liquid lead without melting first.

totalloser
November 10, 2013, 12:56 AM
A goof, thanks. Just getting back into the old hobby. It's been awhile.

totalloser
November 11, 2013, 12:14 PM
I think I was thinking of antimony. :rolleyes:

http://www.lasc.us/ Here's a great resource btw.

So I got rather curious about the sulfur flux out method. A hazardous process worthy of *full study* prior to application. Sulfur dioxide in itself is a caustic agent. But when it comes in contact with water (like in your lungs) it converts to sulphuric acid.

I think my primary concern with such a process is that a wide array of oxides are likely to be created in the process- some probably significantly toxic. This gas will cause immediate damage to cillia in the lungs and can cause rapid pulmonary edema (immediate life threat) in extreme cases- such as a thick waft of it accidentally being inhaled.

My suspicion is that such a process can be made relatively safe, but this is less likely to happen in the garage of someone scavenging ruined lead, so a special note of caution might be in order.

Grain of salt is also in order since I am less than a layman on the issue, but the process appears to have hazards worthy of significant note.