I have about 60 pounds of 30/1 lead/tin alloy which I believe is contaminated with zinc. I have not been able to get good bullets all year long, (about 7 attempts). I read somewhere that sulfur will remove zinc, (not sure if it is safe ) and that sawdust will also do so. Does anybody have any recommendations? 
Thanks!
Joe S

Dave is correct if the zinc is still in solid form mixed into say range lead or wheel weights. During melting the zinc pieces will float on molten lead and can be removed.  Unfortunately, some of the zinc will dissolve into the lead and make a real mess.   

Once the zinc is dissolved in the lead then the lead will have to be "refined".   There are several ways to do this, none of them very easy or perfect.   Adding sulfur to the molten lead mixture is one way but it has problems.   The sulfur forms zinc sulfide which floats on top of the lead and can be skimmed off.  A major problem is the sulfur burns and forms sulfur dioxide which is both quite harmful and will corrode steel.   I would only do this outside with proper safety equipment and a breeze.   It may require several treatments to remove the zinc.   Copper is also removed by this technique.  You will have to remove all of the remaining sulfur and flux the lead to clean it up.   

The other way to remove zinc is to oxidize the lead using compressed air.  This is really risky because if you have some condensed water in the air line you will have a big explosion!  If you want to do this I would use a small steel tube (1/4") and a needle valve to control air flow.    Oxidation will also remove tin so maybe this is not such a good idea.   It has to be done at a high temperature (say 800 F) and will make a lot of lead fume.   

Good luck and be safe, 
Dave 

On reflection I think you are better off, and safer, if you just sell the lead for anchor or fishing weights.    Even if you only got half price you would be better off buying pure lead and pure tin and making your own alloy.   

Even if you did decide to de-zinc with sulfur you would make a mess and it would probably take several treatments, but even then you would not know what you ended up with.   Heating the lead to red heat (watch the fume) and allowing it to oxidize will remove the zinc but also the tin.  You will make a lot of dross (scum).  You will also not have a clue what the residual tin concentration is although measuring the hardness might give a clue. 

For fire refining lead I recommend that in addition to the normal safety equipment for casting molten metal lead I would wear a face shield and a respirator (not dust mask), not something most people have.   

Sawdust will not do anything at all.  I don't know why people say that but it sounds like folk lore.  There are so many misleading and downright dangerous suggestions on the Web that I would be very careful.   

Good luck, 

Dave

Depending on your annual consumption of Schuetzen bullets buying pre mix good quality tin/lead from Roto Metals is cheaper than cleaning up junk lead. Figure the gas alone not even counting the time spent. 

Your bullet is the key to success false economy to shoot the cheapest possible material in the most important  component.

Boats

I had no idea such technology existed. I will contact some of the local scrap dealers to see if anyone can to that for me. 
Regarding the purchase of alloy from Roto Metals, my annual consumption of 30/1 alloy would be about 70 lbs per year at a cost of$205 plus $72 for shipping for a total of $277. I agree that spending hours trying to use contaminated lead would not be productive, but as long as I have several hundred pounds of lead pipe it is cheaper for me to give the contaminated lead away and make up a new batch, so that is what I will do. 
Thanks for your help everyone!
Joe S

Joe, 

If you really have just lead pipe then I think you can recover some very good lead if you don't include any soldered joints (they look larger than the pipe) and don't add any wheel weights or other 'unknown' stuff.  I've used a lot of lead pipe that I was able to buy at a local scrap yard.   It was dead soft and worked fine.  I ran out of that stuff and have switched to RotoMetals for pure lead.  The postman hates me

You can also add tin by finding some 50%/50% lead/tin solder.  It is probably more expensive than just buying pure tin from Roto metals or some other source but it will be fine.   

I'm not a big fan of the quickie X-Ray machines.  They are OK for identifying one metal versus another but to detect lower percentages of zinc, tin or other crappy alloying agents in lead they would need to be calibrated against known standards before they can be trusted.   That is expensive and not likely to happen.   

Good luck, 

Dave

Sell it. All done. Not to be a wise guy but a lot of effort and in the end you will never be sure of your Alloy. That is critical because you need to know how to reproduce an Alloy that produces really good shooting. Just my thoughts as I have followed this thread. Regards FITZ-G.

Be carefull some of the old roof flashing was  zinc it came in rolls about 12 inches wide and about .060  thick it's stronger than lead for the same thickness, it will dam sure mess up your mix.
HTH  LD1