How much zinc is too much in WW

[johnly]

I have one of those fancy XRF tools that will measure the tin, lead, zinc, antimony levels in metal samples.

I picked a bucket of wheel weights and checked what looked to be an old one and another that seemed to be of a newer manufacturer.

The old one had an antimonly concentration of 4.7% and a zinc level of 0.2%, the newer looking item measured 4.3% antimony and 0.7% zinc.

I'll measure a few more, but the question is how much zinc in the alloy will be too much?

John

[454PB]

I imagine most of us want (and expect) 0% zinc in our alloy. If you've found ANY in raw wheelweights, other than actual zinc WW's, it's surprising to me.

Since you have the test equipment, it would be interesting to most people on this forum to learn more. You are better equiped to answer this question than most of us. Of course you'd have to deliberately intoduce zinc into an alloy to find the percentage point where it causes casting defects.

Also, what percentage of tin did you find in those WW's?

[Typecaster]

The grail has always been to have no zinc...but the practical answer is that if the alloy still casts OK, it's OK. I've never had problems that I could attribute to zinc; but then again, I never had a way of quantifying what was in a batch of alloy.

You could be a real popular guy on this site if you offered inexpensive alloy assessment. I will do a melt of 100-120 lb. of lino or WWs at a time to be sure the batch is consistent, and it would be educational to send you a sample mini-ingot to find out the true content. I'm sure a lot of the zealots besides me would be interested as well.

[Ricochet]

I recall seeing a figure in the Metals Handbook for zinc content that could adversely affect casting. I'll see if I can find it.

[johnly]

I'm not too surprised to see some zinc in wheelweights, as there is no need for it to be a high purity alloy, and it could well be manufactured from reclaimed material.

Where a high purity alloy is required, like the solder used in the electonic industry, I wouldn't expect to see any zinc in the alloy( and I don't).

John

[johnly]

I just finished measuring a bunch of lead and wheel weight samples, the results show a great deal of variance between samples. Not good. 3 of the 10 samples had detectable levels of zinc, with the highest measuring 8.67%. The antimony levels hovered in the 3-4% range, and tin in the 0.6% to 1.2% range.

This level of variation seems to indicate that WW are made from what ever scrap lead is fed into the machine.

If the WW smears with a wire brush, is very soft and likely to be free of zinc. I had samples that buffed up, without smearing and some of them contained zinc, others didn't. Crap. No easy ID using that test.

John

[DeanoBeanCounter]

:oops: I've read it someplace before but I forgot. What undesirable effect does zinc have on boolits?
AND
johnly
Where does the equipment come from to test metal content and how much does it cost? Maybe somebody rich on this forum would want to buy it too. That's just not me though. :violin:
Deano

[redgum]

Wow - Interesting indeed.
I guess it's inevitable that they'd all get smelted together when sent back for recycling (?)

[Lloyd Smale]

I know i notice a big difference between batches of wws when i cast as to castablity. Ive suspected that they were contaminated from recyling but who really knows. I wouldnt think theyd intentional add zinc as its lighter which isnt what you want in a ww and its also more expensive. I too would be intersted in what a machine to check it costs.

[imashooter2]

I too would be intersted in what a machine to check it costs.

http://www.americanrecycler.com/03spotlight03.html


John Hunsaker of SOS Metals, Gardena, California notes, "Prices on hand-held units have come down dramatically in the past three years, but these things still aren't cheap." Scrap metal recyclers can expect to pay roughly between $20,000 and $35,000 for a hand-held OE or XRF analyzer. Larger analyzers - such as those for laboratory use - can cost as much as $50,000 or more, depending on options or custom programming.

That page was from 2003. I found another place that would lease them for only $800 a month. I just may wait for the prices to fall a bit more...

[DeanoBeanCounter]

I just had to ask. Didn't I?
Deano

[Lloyd Smale]

ouch!! for that price it had better not only tell me how much is in it but better remove it cast the bullets and even load the ammo and go search on weekends for more lead to test!

[randyrat]

Does anybody here have any contacts with anybody in the New WW business that we could ask. How much Zink is allowed in your new WWs? ect....

[Bass Ackward]

Metals prices have made recycling popular. This has never been to this extent before.

Do you think they are going to separate? Especially when they can just alter the mold size for the weight they need?

In fact, it may be cheaper to alloy with some zinc for hardness than using antimony alone.

This could have profound effects on casting. All molds may need to be iron or steel at some point just to cast well since they hold the most heat. Casting pots will need bigger spouts. Sprue plates, larger holes to get the mix in there.

Ah ah, gotch ya. Just kiddin. :grin: (I hope)

[monadnock#5]

There was a program on the History Channel a couple of night ago chronicling the story of base metals and their various alloys. When it comes to lead, there is a huge mining operation near St Louis IIRC. The lead in the tunnel walls allows them to open huge shafts that don't require support. I don't remember how many tons a year they're moving, but the figure that did make a dent was that 98% of lead products produced are being recycled.

Now I know that the tire shops don't segregate lead from zinc, I know the local scrap yard doesn't either. Just where in the process is the segregation being done? I'd bet no one does. Since wheelweights don't require a high degree of purity to be effective, whatever goes into the pot and isn't skimmed off gets molded.

[Ricochet]

I found the reference to zinc in the section on the effect of impurities in type metals in the Metals Handbook. Said that it increased surface tension and would cause problems, especially when the level went over 0.1%.

The specified levels of zinc aren't over 0.002% in any commercial grade of new lead.

[Bret4207]

You could be a real popular guy on this site if you offered inexpensive alloy assessment. I will do a melt of 100-120 lb. of lino or WWs at a time to be sure the batch is consistent, and it would be educational to send you a sample mini-ingot to find out the true content. I'm sure a lot of the zealots besides me would be interested as well.

I was thinking the same thing.

[Tom W.]

Too much Zinc is said to give the alloy a consistency of oatmeal. I dunno that to be so, but that's what I've read somewhere...

[johnly]

The unit I have is a year old and with the various software options came to ~$40k.

John

[leftiye]

Well put it to work! Just so long as it works! Wish I could afford one(40K$? dern!)

[Ricochet]

Zinc crystallizes at a much higher temperature than lead and the other elements alloyed with it solidify. Makes a light sludge that will separate out and unbalance the bullet. If you could suddenly chill the liquid metal from a temperature where the zinc was mixed in the liquid, it wouldn't be much of a problem, but that won't happen in our moulds.

The Metals Handbook points out that antimony also crystallizes out first and can separate from hypereutectic alloys (lead-tin-antimony alloys with more antimony than linotype), and that they are normally chill cast in typemaking. Sounds like they need to be cast with the metal and mould temperatures as low as practical.

Also, that means that the high Brinell hardness numbers for these hard type metals (as high as 34 for some) are measured when they've been chill cast or quenched.

[ssn vet]

I'm curious what the hand held XRF publishes for sensitivity.

Got to put a +/- on most measurements for them to really mean something.

Heck, at only $40K, I'm sure it will soon be added to the list of "must have" items for home casters :)

[johnly]

It's good for detecting less than 0.1% concentrations.

There are matrix effects, so the absolute accuracy is only going to be about +/- 20%. Even using the most advanced analytical methods, getting accuracy below 5% is a tough task. Been there, done that.

John

[HORNET]

johnly,
Since you gained about 3500 close, personal friends by admitting to actually having one of those analyzer thingies, let me be one of the first to abuse the friendship. If you check a couple of the other current threads, you'll find reference to salvaging useful alloy back out of dross. A couple of others have mentioned that there is often a dense dust left after the alloy is recovered. Any idea what this is?? I know JOEB33050 was looking for somebody to analyze it a while back. I'd hate to think I might be losing something I want back in my alloy, like antimony. Inquiring minds want to know....

[johnly]

The dense dust is likely lead dioxide as a major component.

Fluxing can help bring the oxide to the surface, but it can not reduce lead oxide back to lead metal. If you heated the dross in a hydrogen furnance, you can reduce the oxide back to metal, but it would hardly be worth the effort.

John

[leftiye]

Johnly,
We've been through this a lot of times here. Not at all trying to be upsetting here, but many who typify themselves as "metallurgists" have posted here, and waged war with whomever rose to the occasion. Not trying to start another such flaming debacle, but aren't there "fluxes" (should correctly be called chemical reducing agents) that will reduce those oxides?

I was about convinced that maybe the heavy oxides in my casting pot were lead dioxide, and that I have found a way to reduce them. Tin oxides form almost instantly on the surface of lead alloys, and fluxing (I know, improper term) visibly and instantly dissappears (reduces) them. Beyond that, there are no lead oxides (ever) skimmed off of my pot, and none to be seen. Just add more lead, make more boolits.

[johnly]

I'm a chemist, not a metalurgist. To reduce lead oxide to the metal form, you must introduce a material that had greater affinity for the oxygen than than the lead oxide and elevate the temperature so that the reaction will occur.

A thermite reaction is a good example of this, mix some iron oxide with aluminum or magnesium powder, elevate the temperature to the critical point and the magnesium/aluminum will rip the oxygen atom away from the iron atom to form magnesium/aluminum oxide, and generate a lot of heat in the process. This reaction proceeds because the thermodynamics favor the formation of magnesium/aluminum oxide over that of iron oxide.

Stearic acid, waxes, and the other common fluxes used by bullet casters don't participate in this type of chemical reaction. If you have a specific material in mind, I can look into its redox potential with lead oxide.

John

[trooperdan]

John, it is generally accepted as gospel among us casters that carbon in various forms will reduce the oxides back to metal. Sawdust with a high resin content plus some stearic acid has proven popular. I've used crushed charcoal and walnut hulls as well. Does the science of this hold up?

[johnly]

Yes.. There is a chance that carbon could react with a metal oxide to produce carbon monoxide or carbon dioxide and the base metal.

Another possibility is the formation carbon monoxide during the fluxing process. Carbon monoxide is a reducing gas, similar to hydrogen, and that is the metal oxide reduction process.

John

[leftiye]

What could we use to bring about available hydrogen in a flux? What form of Carbon would have the highest affinity for oxygen (carbon monoxide?)?

In previous wars on this subject it was found that there are many easily available experiments done (often by solder producers) that produce lead and tin oxides and then reduce them again (at the lower temps in which lead is molten but not fuming visibly- 450 to 750 degrees).

Is it possible that reducing tin and lead oxides are more readily accomplished than some sources believe? Again (whether or not I am succeeding) I'm trying to keep this friendly- don't read anything in to it.

[johnly]

Let's just say you want to avoid the hydrogen process. Hydrogen has a very wide explosive range in air and there are many safety aspects that would need to be implemented to even use the process. It's simply not worth the risk and effort for lead smelting.

If carbon monoxide is performing the oxide reduction, then heating dross/charcoal mixture in a almost sealed container like a covered dutch oven should maximize the effect. This experiment won't distinguish if the reduction is caused by the carbon or carbon monoxide, but it nothing happens, then we'll need to come up with another theory as to what is occuring when fluxing a pot.

John

[Ricochet]

Not necessarily. There might be compounds in some fluxes that would produce carbon monoxide at lower temperatures than charcoal will. Indeed, some might release hydrogen.

I was a disbeliever in the ability of any flux to reduce the metal oxides at casting temperatures, too, but others have posted pretty convincing experimental evidence that it occurs. There are extensive discussions of the topic in the archives.

[johnly]

The formation of hydrogen in the pot during fluxing is unlikely.

John

[leftiye]

One of the chief drawbacks to the use of charcoal indoors (the ancient -possibly still done today- Chinese used to carry charcoal braziers around with them for warmth) is that it produces a lot of carbon dioxide- and a lot of carbon monoxide poisoning. As a covering for molten metal (crushed charcoal), it may be a nearly ideal situation to produce carbon monoxide, as there isn't a lot of oxygen down inside the granules, and there is high temperature.

[testhop]

guys on the lighter side do you think
this zinc thing is being done by the anti gun bunch (darn liberals) cant trust em lol

[johnly]

Now that's an Oliver Stone moment.:drinks:

John