Zinc contamination?

[singleshotbuff]

Gentlemen,

I think I may possibly have gotten some zinc mixed in and melted with some wheelweights I was smelting the other night. I rec'd 2 buckets of wheelweights from my source and was smelting it into ingots using my turkey fryer burner and a cast iron pot. I loaded the pot and left it sit for awhile to tend to some other things. I had the pot running pretty HOT. Anyway I came back later and found some clips in the melt that looked like they had been riveted on the weight. I have read on here where that may indicate zinc. Also the ingots I poured after I added this metal seem to have a lighter color than earier ones.

Anyway, assuming I did get zinc melted in with my WWs, what is going to happen when I cast? I always run the pot hot when I cast, don't mind frosted bullets, so I don't see a problem with the zinc not remelting or casting. Will my mold fill out? Will I ruin my mold if I use this suspect metal? Can I dilute it enough, by using 1lb of the suspect metal to 10lbs pure WWs, to make it useable? Should I chuck the whole bunch (45-50lbs of metal)?

All help is appreciated.

SSB

[felix]

SSB, no problem. Just keep diluting what you just made with another batch. Use your 10-1 ratio like you suggested. If you suspect it, then assume it as fact or not, and then compensate for the mistake automatically. ... felix

[44man]

I agree with Felix. I would not waste all that lead. A few zinc weights will not hurt and you are not even sure that they were zinc. If you melt the WW's from now on, keep the temps lower so the zinc can't melt.

[357maximum]

I contaminated about 50 pounds once, well in advance of knowing any better. I did not try to dilute it, I just used it for some 38 wadcutters that did not need to be perfect, and some decoy weights. It still cast decent, it just would not fill out perfectly in some of the more intricate moulds. If you suspect it, melt an ignot seperately, and when you have your most complicated mould up to temp and working good with known alloy. Use the seperate melt and try it(melt it over a coleman stove if you have to in an old non aluminum pan). Personally I would be afraid of ruining more precious metal with the dillution method if it truly is zinc fouled. I save all my iffy looking ww and melt them seperately in a batch everytime a fishing buddy needs some catfishin weights. They come over to use one of my 20+ do-it molds and I simply put their pretty ww's into my stash, and let them have at it with the iffy stuff. win win situation, they get their chicken gut sinkers and I get more wheelweights, everone is happy with the situation when I explain it,no one trying to sink chicken guts ever seems to care..

Michael

[LET-CA]

The only thing I've read is that fluxing with sawdust will help pull some of the zinc out. (One of Glenn Fryxell's articles) Good luck, hope you don't lose a whole pot of lead.

From Glenn's article

"Of particular interest to the bullet caster are calcium, aluminum and zinc -- all of which are difficult to reduce and all of which cause casting problems if present in any significant amount (they muck up the surface tension of the alloy and prevent the alloy from filling out the mould properly). As the sawdust chars, it can be thought of as a kind of activated carbon. Both the lignin's of the original sawdust and the oxygenated sites of the activated carbon are very effective at binding metal ions like calcium, aluminum and zinc. Thus, the advantage of sawdust is that it does both jobs, returning the tin to the melt and removing the problematic impurities. Sawdust has the added benefit of being free."

[GP100man]

Singleshotbuff im with 357 max try casting before condeming .Isave mine for plinking . If you have zinc run heat upto 800f then let cool to barely melting flux&skim with outstirring you takesome good with the bad , but I usually get satisfactory plinkers. Iknow ive posted it before probably leaving out something.butgo by the look of the melt when cooling down most , not all of the zinc will clump in the center if melt clumps on outside of center that is lead solidifying. then i save thezinc for gut sinkers .

[mazo kid]

If you bring your temperature up slowly, to just where the lead melts, could you see the zinc in the center of the pot? Or could that also be antimony? Just askin', hoping for a simple solution. Emery

[GP100man]

mazo kid i run temp up first then let cool down .then in the middle a clump forms.i skim that out 1or 2 times & pour some boolits may have to repete. but i usually put these boolits in the plinking can.

[mazo kid]

Thanks GP100man, I'm not even sure I have any contamination, but next time I cast some WWs I'll see what happens. Emery

[largecaliberman]

Singleshotbuff,

In the future, what you can also do is to get a bunch of ww ingots from a previous smelt, once they're melted, stabalize the temp 650 degrees F THEN throw in the "raw ore" a little at a time just to cover the surface of the melt and skim off as you go along adding more wws until you have enough to ladel the molten stuff into your ingot molds. Always be sure that the temperature does not go above 650, some crank it up to 700 but I like to play it safe. FYI, zinc melts at 787.244 F.

What the others said on cranking the temp up then lowering it below the melting temp of zinc is an excellent way of ridding zinc from the melt. Keep in mind though, you can't get 100% of the zinc out. At times, adding a little more tin to the contaminated melt will help.