What is this in my alloy?

[Smokin Gun]

This is very grainy material and about half the weight of a piece of lead the same size. Is this zinc?

[jsizemore]

Did it look lumpy and frothy on top of the melt before you ladled it out?

[Winger Ed.]

Sure sounds like it.

If ya raise the heat up slowly, the Lead will melt, then the Zinc will float up since it melts at a higher temp.

[Smokin Gun]

It was lumpy and I noticed it rising to the top when the pot was cooling down. It was like this stuff was a thick layer on top of the lead as it was cooling

[Winger Ed.]

Lead melts at a lower temp., so it might still be Zinc- since it will solidify sooner, and (possibly) float on top of the molten Lead.

I'd dig around in the 'stickies'. This is a issue that has come up all too frequently, and should be well covered already.

[CastingFool]

Put a drop or two of muriatic acid on it. If it's zinc, it will bubble up. The resulting gas is harmful, so make sure you don't breathe it. That's the main reason to use one or two drops of the acid, to minimize the production of gas

[NyFirefighter357]

Test it with muriatic acid, if it bubbles it's zinc.

[243winxb]

Zinc, antimony and copper may float at lower temperatures. Just as the alloy starts to melt.

I would not treat it as scrap.

[dondiego]

Put a drop or two of muriatic acid on it. If it's zinc, it will bubble up. The resulting gas is harmful, so make sure you don't breathe it. That's the main reason to use one or two drops of the acid, to minimize the production of gas

The gas released is hydrogen and is flammable but not harmful.
H2SO4 + Zn = H2 + ZnSO4

[bangerjim]

Say "HELLO ZINC!" That sure sounds like what you have. What was the source of the stuff you melted? If tire weights, you did a poor job of sorting B4 melting. Like said, test with acid to see if any reaction. (You can even take a couple drops of battery acid out of your car to use if you do not have sulfuric (H2SO4) or hydrochloric (HCl) acid around. I have gallons of HCl around, as that is pool treatment acid. Pb, Sn, and Sb will not react to the acid. Zn will fume and bubble up. Concentrated HCl fumes on it's own and do NOT breathe the yellow vapors that come off it!

I would scrape it off and keep for later analysis or disposal.

banger

[CastingFool]

The gas released is hydrogen and is flammable but not harmful.
H2SO4 + Zn = H2 + ZnSO4

I stand corrected. Thanks!

[oley55]

Ditto on testing with muriatic acid, if for no other reason than setting your worries to rest.

If you don't have any or do not wish to be storing a quart/gallon of corrosive muriatic acid around your home or anywhere near your reloading equipment, you can easily make a tiny batch with citric acid, table salt and tap water. I mixed up some a couple weeks ago just to validate it does in fact work. It is not so strong as to boil n bubble, but after 30 seconds to a minute upon close examination you can see the tiny bubbles coming up through the drop of acid.

the mix ratio is 1/4 tsp of citric acid (I used Lemi-Shine), 1/4 tsp of table salt and 2 tsp of hot tap water. Mix until the citric acid and salt is dissolved and you are good to go. Just put a drop on your suspect metal and watch for a reaction. The solution seems pretty weak and I question whether it could identify small amounts of zinc dissolved in an alloy, but it works on known zinc. Deposal of this tiny amount can be accomplish with a good volume of flushed water or neutralized with some baking soda.

I found this on on the web somewhere very recently (maybe even here on castboolits), but don't remember where and haven't been able to find it again.

[jsizemore]

Did you end up with clean alloy after you removed the stuff pictured in the original post?

[bangerjim]

Found on the net:


Both Sodium Chloride and Citric acid are white crystalline solids. NaCl is a neutral ionic compound that completely dissociates into Na+ and Cl- ions when dissolved in a polar solvent such as water. Citric acid is an organic compound, a tricarboxylic acid (three COOH groups) that partially ioinizes to a H+ and (Citrate)- ions in equilibrium with the un-ionized citric acid when dissolved in water.

The two substances can be MIXED together to form a mixture. However, they do not chemically react with each other.

NaCl + Citric Acid <==> Citric Acid + NaCl.

This mixture can be used as a saline buffer for biochemical reactions. However, there is no new chemical compounds formed when you mix NaCl with Citric Acid (for example, HCl and Sodium Citrate are NOT formed).

Best to use the real thing. And store it outside NOT inside around anything you value! It does fume thru many plastics, so keep it in a GLASS container.

The internet actually IS your friend, if you use it properly and have safeguards in place.

[oley55]

as soon as I complete my introductory chemical-engineering 101 course I'll try to finger out those web search results....

[WRideout]

Some brands of toilet bowl cleaner are simply dilute Hydrochloric acid.

Wayne

[NyFirefighter357]

Ditto on testing with muriatic acid, if for no other reason than setting your worries to rest.

If you don't have any or do not wish to be storing a quart/gallon of corrosive muriatic acid around your home or anywhere near your reloading equipment, you can easily make a tiny batch with citric acid, table salt and tap water. I mixed up some a couple weeks ago just to validate it does in fact work. It is not so strong as to boil n bubble, but after 30 seconds to a minute upon close examination you can see the tiny bubbles coming up through the drop of acid.

the mix ratio is 1/4 tsp of citric acid (I used Lemi-Shine), 1/4 tsp of table salt and 2 tsp of hot tap water. Mix until the citric acid and salt is dissolved and you are good to go. Just put a drop on your suspect metal and watch for a reaction. The solution seems pretty weak and I question whether it could identify small amounts of zinc dissolved in an alloy, but it works on known zinc. Deposal of this tiny amount can be accomplish with a good volume of flushed water or neutralized with some baking soda.

I found this on on the web somewhere very recently (maybe even here on castboolits), but don't remember where and haven't been able to find it again.

Home Depot sells 30% vinegar that should work too.

[kevin c]

Muriatic acid is hydrochloric acid, or HCl. H2SO4 is sulfuric acid. I believe both produce hydrogen gas on contact with metallic zinc.

When processing antimonial lead, if the melt gets too hot I'll get a skin of oxides on the surface that looks like that when skimmed out.

[dondiego]

I stand corrected. Thanks!

Actually the fumes from either hydrochloric acid or sulfuric acid are toxic and can cause bad burns so it is a good idea to not breathe any fumes!

[oley55]

Some brands of toilet bowl cleaner are simply dilute Hydrochloric acid.

Wayne

I tried some Lime Away Bowl cleaner just for grins and can report virtually undetectable reactions on a zinc ingot. I'll assume it is too diluted for our purposes.

[bangerjim]

I tried some Lime Away Bowl cleaner just for grins and can report virtually undetectable reactions on a zinc ingot. I'll assume it is too diluted for our purposes.

Wrong chemistry! That stuff is basic, you need acidic to test for Zn. Just take a few drops out of your car/truck battery. You will never miss a few drops. That is H2SO4 in your battery, but HCL is more aggressive for metals testing, as it's hydrogen ion concentration is much greater.

[oley55]

Not too sure about 'wrong chemistry' since the stuff contains 5-10% hydrochloric acid, at least as per the MSDS. http://www.rbnainfo.com/MSDS/US/LIME-A-WAY%20Toilet%20Bowl%20Cleaner%20EN%20GHS.pdf

Substance/mixture : Mixture
Hydrochloric acid 5 - 10% 7647-01-0
Amines, tallow alkyl, ethoxylated 1 - 2.5% 61791-26-2
Alcohols, C12-15, ethoxylated 1 - 2.5% 68131-39-5


Likely 'it's too diluted' for our purposes.

[bangerjim]

Wife has a very old bottle of the stuff and the label indicates no acidic content. They must have changed the make-up over the years.

10% HCl is strong enough to get a reaction.

[GregLaROCHE]

You can buy a gallon of HCl cheap at a pool supply store. Use it to test the unknown metal and then keep it around. It can be quite useful for removing corrosion from metals, if you are careful handling it.

[oley55]

You can buy a gallon of HCl cheap at a pool supply store. Use it to test the unknown metal and then keep it around. It can be quite useful for removing corrosion from metals, if you are careful handling it.

No doubt, but I had presented the 'make your own' as a option for folks who do not have a wooden barn or shed to store the stuff. From my experience the acid tends to leach through the plastic bottles in something similar to vapor and will cause damaging rust/corrosion to any nearby metal (and that includes the very nails/screws holding a wooden structure together).

[kevin c]

...From my experience the acid tends to leach through the plastic bottles in something similar to vapor and will cause damaging rust/corrosion to any nearby metal (and that includes the very nails/screws holding a wooden structure together).
(NODS HEAD VIGOROUSLY IN AGREEMENT) Lordy, yes. I'm still finding rusted tools in my shop from when I made that mistake, usually ones stored within three feet on the bottle. I'm just hoping the water heater and furnace on the side furthest away are OK.

[GregLaROCHE]

No doubt, but I had presented the 'make your own' as a option for folks who do not have a wooden barn or shed to store the stuff. From my experience the acid tends to leach through the plastic bottles in something similar to vapor and will cause damaging rust/corrosion to any nearby metal (and that includes the very nails/screws holding a wooden structure together).[/[QUOTE]QUOTE]

That’s interesting. I never experienced or even heard about that. Luckily I do have a barn where I store mine, but I wonder what happens in the stores where it is being sold and there are many gallons of it. Perhaps if there is enough turn over, it doesn’t have an effect. I think I have some glass half gallon jugs around to store mine in. I’ll have to use a cork stopper and not the metal caps. Will much seep through the corks?