I have aprox 40 Lbs of wheel weights ,how do i determine if they are lead ?

You should be able to drive a sharp something into them pretty easy.

I think you can also bend them.

Iron weights are marked FE, ferrous, lead is soft, will mark paper, melts easily with a propane torch and tastes different. Well maybe, I never tried

the steel ones are huge for the weight and sliver. the lead ones are tiny, dull dark grey and soft. lead wheel weights havent been a thing for like a decade. not likely to find them these days.

I use a magnet and a side cutters.

cut with side cutters

Lead is obvious then.

Diagonal cutters to be sure. You only have to nip at an edge. Lead will nick, steel or zinc won’t. Lots of other methods, but diagonal cutters are hard to go wrong with.

Just don’t melt the zinc ones with lead ones you will contaiminate your lead

Lead alloys can typically be scratched by your thumbnail if you need a quick and easy method that requires no tools.  You won’t be doing that with zinc or steel.  

Lead, zinc, and steel wheel weights are all quite different once you figure it out.  You can sort by hand, and verify with the side cutters.  

One caveat- Once in a while one will look just like a lead WW, but turns out to be something else, maybe zinc alloyed with lead (?) and it won’t melt as easily, despite being made just like a lead WW.  Those are few and far between though, thankfully.  Usually they are pretty different.

Yup. Even a squeeze with the side of a pair of pliers will leave a mark in lead and do nothing to zinc or steel.

This is how I do it too and you can get pretty quick.

I've been sorting weight for many years and I'm currently going through seven more 5gal buckets (my wife has worked for car dealerships for 30 years and is able to get a constant supply of WW's from all the mechanics, tire/wheel techs and vendor as well as mechanics from dealerships she's worked in the past and has remained friends )

Also, a ~99.9% reliable way is: the clips on steel weights are (IME) riveted on (and typically have "Fe" cast into them) and Zinc have "Zn" cast into them.

Stick on's are similarly marked as well.

Of course, there's always the possibility of getting an oddball here or there

Finally, drop on a concrete floor will result in a "ping" noise with steel and even zinc but lead will hit with a dull thud.

The easiest method I have ever found to sort weights is by sound. I also keep a strong neo magnet nearby which can verify odd sounding ones. Finally a pair of nippers, like a big side cutters, normal dikes are usually a little small, can be used to verify any that are questionable. Lead dents easy, where steel and zinc don't really at all. Pick out some weights, and find ones that you know for certain are steel, zinc, and lead. They are often stamped or cast right into the weight. It does not take long to hear the tink vs thud of steel and zinc vs lead weights on a solid metal surface. I use a big chunk of steel round stock. I couldn't imagine sorting a 5 gallon bucket all by hand and pliers, you would be there all week.

You should probably also sort by clip on wheel weights, and stick on wheel weights. Clip on weights are generally a harder alloy that contain lead and antimony. There's some tin, but it's not a ton. A lot of people add about 2% tin to clip on weights, and that makes a nearly perfect bullet alloy for a lot of things. Stick on weights on the other hand are very close to pure lead. I consider them pure lead, and I use them for muzzleloader and other things like that. Or you can mix them with tin, such as 5% tin to make 20-1 alloy, which is nearly ideal for expanding bullets like hollow points. You could mix your clip on and stick on weights together, but I think they are worth sorting.

Some other things you will run into are random garbage, as well as odd weights, plastic stuff, I just toss all that nonsense. I keep my zinc, but I haven't done anything with them yet. Some people cast bullets with them. I've heard of some people casting certain fishing weights with them. You won't get much for them at a scrap yard, but it's more than just throwing them in the garbage.

Lastly, when you smelt the weights, use a thermometer. Zinc should melt at about 787F or 420C, but some alloys will melt below that. Usually by the time the melt is up to 675ish you can tell if any floaters remain. All lead alloys will melt by 675. Once I am confident I have no zinc in there, I like to get the melt up to 700-725 range. You should not rely on the temp for sorting zinc, but it's a good backup check. Smelting weights is dirty business. The coatings, and oil, grease, random garbage, etc. that finds its way in there is not something to breath. This is not something to be done in a garage. This is something you need to do 100% outdoors, and ideally with a respirator. It's always a good idea to use protective clothing when working with molten metal, but it's not optional with smelting. You need eye protection, thick gloves, and you want fully covering clothing. All natural too, no synthetics. Do not wear synthetic tennis shoes, wear leather. A denim or leather apron is really nice too, because wheel weights are filthy. Obviously do not eat while doing this, and I'd be really careful how you drink.

As I'm getting my melt up to temp, I skim off my metal clips and anything else that floats up. It doesn't have to be 100% clean at this point. Once I get up to that 700-725 range, and back off the flame to maintain that, I flux. I use sawdust from the miter saw. It works as both an oxidizing and reducing flux. The oxidizing flux will help removing some of the odd garbage in the metal, while the sap from the wood will help reduce the lead together, which is mainly lead, tin, antimony, and some arsenic. I do not know the entire science to fluxing. You will want to stir quite a bit during fluxing, as anything non metallic such as charcoal, sand, dirt, or even little bits of metal such as copper wire, all kinds of different things can get trapped underneath the lead.

Stir that as best you can to get all that garbage to the surface to be skimmed off. Use something metal to stir, do not use wood or that wood will char and that char will get trapped at the bottom. I flux twice just for good measure. By that I mean I'll wait for the sawdust to turn to black charcoal, skim all of that off, and the surface of the metal will look perfect. I then add more sawdust, and repeat again. Finally after all that you can pour that alloy into ingots for use. My only suggestion is do not cast too big of ingots. 1 pound ingots are not too small. 5 pound ingots are getting to be a little too big for convenience in a casting pot. I made my own ingot molds out of angle iron, and I think they were around 2.5 pound ingots. If I did it again, I would have them cast 1 pound ingots.

I realize that is way more than you asked for. It's actually been a few years since I've sorted and smelted wheel weights since they are not that great a source of lead anymore. Back when you could get a bucket of weights for free, and nearly all of the weights were lead, it was a no brainer. It depends where you live today, a few states outright banned lead weights, and even where they didn't, lots of places are using steel and zinc now. The last bucket I sorted, I'm not even sure half of it was lead, it was more like 1/3rd. Even worse, it seems a lot of places are now charging YOU to haul out their garbage. One guy wanted $40 for his bucket! So be very carful how you go about it, because you don't want to be spending $40, and getting 20 pounds useable lead from it. The amount of work to turning wheel weights into bullet alloy is far too great for that nonsense. It's questionable if it's even worth getting for free anymore. The last run I did was a sold weekend, like 16 hours of hard labor work, and I got close to 200 pounds of bullet alloy out of that. It's kind of enjoyable in it's own way, but I'm not dumb enough to be spending money to be working that hard.

One of the best sources of lead currently today is recycled bullets. A lot of those are going to be indoor ranges, but some outdoor ranges do mine their berms. It varies so much by range to range. Many just don't sell. You have to call around. I've even heard of some gun clubs that allow members to take all they want for free, and it's not that hard on indoor ranges with bullet traps. The only downside is reclaimed bullets, espcially from indoor ranges, are mostly going to be plated or jacketed bullets that use quite soft lead alloy. It really depends though, some ranges get a lot of cast bullets. The stuff I'm shooting now turned out fine, it's right around 11BHN air cooled, works fine for me. I did add 2% tin. You will want to do large batches just to get consistent alloy. You don't have to melt it all at the same time, just that when you get reclaimed bullets, get like 300# at a time or whatever you can haul or carry.

There is a thread over at Castboolits.com about hand sorting WW's.  They included pictures to help.

https://castboolits.gunloads.com/showthread.php?139839-Guide-to-Hand-Sorting-Wheel-Weights