Zinc in Lead

[243winxb]

Bullets wouldn't pour and fill out well

Don't mistake this for zinc being in the mix. This can be caused by a few things. The mould might be cold. The pot to cold. Oil in the mould. The hole in the bottom pour spout might be to small . Air gets trapped because the flow of alloy is to great and the air can not escape from the mold fast enough. The hole in the mold might need inlarging (don't try this yourself). Sometimes the vents cuts in the mould are not right, or dirty. A drop/drip of alloy fell into the mould before you opened the bottom pour spout. I am sure there are more reasons. I start casting with the pot at maximum temp. , then lower it to around 800-850 when the mold is hot. If the mould is to hot, the bullet will have a frosting on it, this does not hurt a thing UNLESS the bullet loses to much diameter, it alway does a little. Tin always helps the alloy to flow, make sure there is some in the batch.

 

[RustyFN]

I don't put WW's in my production pot because they get too dirty. I use a burner and a six quart dutch oven. I keep the melt between 650 and 700 so that the zinc weights won't melt. Then I scoop them off with the clips. That's a lot easier for me than trying to sort the weights by hand.

Hope that helps.
Rusty

 

[ForneyRider]

I have been doing some research and found a couple of articles.

They discuss, among other things, separating zinc from lead.

One method involved using silver to bond to the zinc, then cupellation to recover the silver from the zinc.

Another method involved high pressure steam.

One part does mention that zinc will bond with lead and not separate, but you can flux, stir, and skim some of it out. I think they mentioned nitric acid and charcoal as flux.


Annual_Report_of_the_State_Mineralogist_.pdf

Handbook_of_Metallurgy.pdf

The above 2 are available on google books.

 

[Bula]

Whenever i smelt into ingots i just start skimming clips as soon ast they start to float. The zinc weights floated like a cork after the lead had just started to melt. I guess if you wait until the whole batch is over the zinc melting point, you'll be in trouble. I guess these zinc weights are getting more prevalent, in about 4-500 lbs i've processed, Ive only seen 3 or 4 individual weights.

 

[zxcvbob]

Whenever i smelt into ingots i just start skimming clips as soon ast they start to float. The zinc weights floated like a cork after the lead had just started to melt. I guess if you wait until the whole batch is over the zinc melting point, you'll be in trouble. I guess these zinc weights are getting more prevalent, in about 4-500 lbs i've processed, Ive only seen 3 or 4 individual weights.

Or if you heat the lead quickly, before it's all melted the stuff at the bottom could be way hotter than the metal and trash on top -- and the zinc can't float up until all the stuff on top of it is melted. If you are very unlucky, a piece of zinc at the very bottom of the pot when you start the melt could get hot enough to contaminate the batch. Heat slowly and you shouldn't have the problem.

I start out with just weights that I can identify as being lead. I melt them and skim them, then I start adding the questionable weights to the liquid that I can control its temperature.

(a lot of the weights that people think are zinc are really just lead with a thick coating of tough paint, like the ones marked "MC-AL")