Need advice

[buletdoc]

I have about 140 lbs. of what I believe to be alloy contaminated with zinc. When I was casting in my mark ll l was getting what would be best described as oatmeal or grits on top of the lead. I had to fully disassemble the pot to remove the alloy. When it came to getting the last out had to use a chisel. I don't want to lose the alloy if possible. A friend suggested soaking the bullets cast in muriatic acid as a trial to see if zinc is present. Then rinsing off with lye drain cleaner. He said he has done this, remelted the bullets and they came out fine. I wonder if this works instead of using silver. He says the zinc is mostly on the exterior of the bullets &the ingots.
Any advice about this would be greatly appreciated. Also do I have to worry about the pot or molds?

[lobowolf761]

I've had the same thing happen to me when I'm smelting down bulk weights and scrap. I'm using a 5qt cast iron pot. When it gets like that I'll Flux the melt a few times scimming off the stuff floating on top of the melt in between the fluxing. I do this at a pretty high temperature stirring the melt every now and then to end up with it as clean as I can get it. Then I put it in the ingot moulds. A full pot of clean melt is a little more than 50lbs. I do this also with alloys periodically I'm not sure of just to makes sure it's clean to cast with. You might want to try this so your melter doesn't get all gunked up again. If I was you this is what I would do. If you have it happen again in your melter try to scim off what you can and keep casting and see what happens. Good casting.

[GabbyM]

If it's just a low concentrate of zinc. You can flux it out with sulfur. Or use copper sulfate to replace the Zn with Cu. Best done outside while standing up wind.

Here is one thread that will overwhelm you with data.

http://castboolits.gunloads.com/showthread.php?172475-High-Copper-Alloys-Lets-discuss-this-further

Forum member popper has written quite a bit on the subject.

[jsizemore]

In the stickys at the start of this forum are 2 that discuss zinc removal with sulfur. Most folks run high heat when casting and end up with the tin and antimony float on top of the melt. It's gray frothy oatmeal looking. Work on fluxing it back into your alloy with a little smash and stir technique. Smash it against the side of the pot with your stirring spoon and then stir it back into the melt. I would do this first before trying to remove the zinc because the zinc bogeyman is always just around the corner.

[buletdoc]

I tried fluxing both in smelting pot and casting pot with sawdust & wax. Stirred with wood stick while smelting, made no difference. I think my temp was too high. What I'm going to do this smelting time is try to keep temp lower so everything but lead floats on top to skimmed off. Last time the clips still had stuff stuck to them and there was much more what I took to be lead on them. First time smelting I sorted as best I could, then dumped into the pot. Must have done something right because the clips came out clean and not as much lost metal. Also no grits in smelting pot or casting, and the bullets were beautiful. I have to figure this out as right now have 20 5 gal. buckets full and am due to get at least 5 more in a couple of weeks.

[Yodogsandman]

I had a batch of range lead that I thought was zinc'd up. I checked it with hydrochloric acid and it was fine. I still haven't re-smelted it. I'm thinking that it will be OK for fishing weights remelted and poured with a ladle from my smelt pot.

[trapper9260]

I tried fluxing both in smelting pot and casting pot with sawdust & wax. Stirred with wood stick while smelting, made no difference. I think my temp was too high. What I'm going to do this smelting time is try to keep temp lower so everything but lead floats on top to skimmed off. Last time the clips still had stuff stuck to them and there was much more what I took to be lead on them. First time smelting I sorted as best I could, then dumped into the pot. Must have done something right because the clips came out clean and not as much lost metal. Also no grits in smelting pot or casting, and the bullets were beautiful. I have to figure this out as right now have 20 5 gal. buckets full and am due to get at least 5 more in a couple of weeks.

What I do is just fill the pot with the WW and melt it at low heat like you did that way it will have the clips and the zinc will float and just clean it off after. Then I would put in igots and start over again for the next batch that way you keep the heat down and all the ZN will be on the surface.I do flux also.

[RogerDat]

Acid will fizz if there is zinc. Test with that and at least you will confirm your suspicions or indicate that there is something else going on.

Sounds like you smelted WW's and might have been hot enough to melt the zinc WW's also. Even if you keep the temperature down it is possible to have some zinc ones get trapped on the bottom and melt. I use diagonal cutters (dikes) to "nip" each WW, the zinc are too hard to nip, lead nips easily. More work but then I don't have to worry about any zinc getting in. So far while smelting I have found 2 WW's that would not melt that I missed.

[CastingFool]

I just got a batch of wheel weights, and sorted them using a pair of dykes, just as RogerDat described. Tedious, yes, but I rather do that than end up with contaminated lead.

[runfiverun]

missing a zinc ww won't even be noticeable in a batch of melting ww's.
you have to get the zinc component up over 1.6% for it to be noticeable and affect the alloy enough to make you change the way you cast.
2% will show the floating oatmeal and affect the spout negatively.

if your sure you have zinc.
melt the alloy and scrape the oatmeal out then cut the contaminated alloy with good alloy.
fluxing with sulpher will help and make the repaired alloy cast very well.

[buletdoc]

I don't think my neighbors would like the sulfur fumes in the neighborhood. Any body think the idea o soaking in mureatic acid then rinsing off with lye drain cleaner, then remelting. My friend did this with some bullets that he thought had zinc and things turned out fine. I hate to seem stupid about this, that's why I'm asking here. Will the remelting with higher temp. then lowering temp. & skimming after several fluxings with sawdust? I have always found good advice here so please help.

[scottfire1957]

Analysis at a scrap yard.

ETA: will tell you if it's Zn or technique.

[runfiverun]

proper fluxing will try to make the zinc alloy in.
lowering the temp and scooping it out will get a bunch but be aware you will pull some of the tin out with the zinc.
get what you can out then cut the contaminated alloy with enough good alloy to make it useable.
that might be 3 to 1 or just 1 to 1.