Smelting by Temperature

[ACrowe25]

I have an excellent source for WW, which 90% are lead. But I've been sorting them by hand and after the 15th bucket full, I'm sick of it lol!

My father owns a heat treating shop, with access to very large accurate furnaces... My thought was throw them all in the Dutch oven pot I usually cast in, close the door. Set at.... 700? For 10 minutes or so and pour off with my laddle after skimming off the zinc/steel.

Now ow my questions for you vets:

1.) 700? Will this ensure no zinc yet be hot enough? Those who smelt only by thermometer what temp do you ensure you do not go over? What should I set he oven at (they're AT WORST 5 degrees off but by law they're +\- 15 I believe).

2.) how fast will this cool? I can keep putting it in/out but wondering if I should bring an extra heat source. But this would just complicate things.

3.) any other tips guys?

I'm asking you guys as I live quite a distance from him, and I'm home for the holidays and we're going to do it tomorrow.

Best,

[Idz]

The fellow I worked with years ago would never allow lead or zinc in his furnace. If you spilled some it would contaminate the furnace when he ran it at higher temperatures. Better check out if that is a problem before you proceed.

[jsizemore]

Try a small batch and see your results. I like to separate the SOWW from the COWW which is my regular source of pure Pb. There's plenty of folks on here that don't and do separate with success. As long as you can control your temp you should have success.

[ACrowe25]

I should clarify from a PM I got...

I know the equipment well, working here allowed me to work my way through college. So I'm well aware of safety.

The plan was to place the dutch oven in a metal basket with hi-lo accessible bottoms, where the hi-lo would load it in, and remove it. I would then skim/flux/etc. And re insert if needed.

It was never the plan to open a "oven" and skim etc while inside. These are industrial furnaces, ranging from sizes you can insert full semi+ trailer to the size that can fit a Small 4x4 ATV (which ill be using).

I confirmed that the temp range AT WORST near the edges is +\- 15. Generally +\- 3.

PM did bring up a good point about safety. Will allow it to sit at 200 for 15-20 to drive off any water so I don't ramp up to 700 too quickly.

[lightman]

Sorting is a PITA, but is goes better and faster if you have a shooting buddy to help. Not many of us have access to the kind of equipment you have but it should work fine. As in any new adventure, you will have to refine the process. Expect the first pot to take you longer than the later ones. Sounds like fun, wish I could watch! Happy New Year!

[Geezer in NH]

So no temp answers huh????

[KYCaster]

I think I'd set the temp so the top of the cycle would not exceed 700F. Initial over shoot, if any, shouldn't be a problem since the temp should stabilize well before the entire batch reaches melting point.

You said dutch oven so I assume you're talking about batches less than 100 lbs. Ten minutes to melt 100 lbs. seems pretty optimistic.

I'd find a basket made of 1/4" mesh to nest inside the pot. Load the WW, give it time to melt, lift out the basket with the clips and unmelted material, flux, stir, return to the oven for a short time then skim the remaining dross and pour your ingots.

Seems like poor use of oven capacity to me. If this is going to be a regular endeavor, I'd find a way to do 300 to 400 lbs. a shot.

Just my .02.
Jerry

[lwknight]

I would recommend 650-675 if it's an option. Otherwise:

You don't even need to care about temperatures if you are right on top of it. You will need to start with a 1" or so layer of known to be lead in the bottom.
When I get buckets of junk, here's how I do it.

With a solidified layer about 1" thick ( does not have to be cold) just pour all the junk on to it and start heating. Water will dry and oil will smoke. Eventually the pile will start sinking. This is the time to start rolling/stirring with a strong rod like 1/2" steel. As the lead melts out it will keep the temperature below where zinc melts.

When you notice that everything can be dunked in liquid its time to dip off the floatie stuff quickly because the pot is still heating and will soon melt zinc unless you have the temp limited.

One caveat is to know that when you have tin content in the pot , it can start dissolving zinc even below melting temperatures. A small amount of tin and a short stay time will not dissolve enough zinc to be concerned about.

[remy3424]

Like the idea of the mesh basket to pull the clips and any stray "zincers" out...should galvanized hardware cloth formed to the shape of the pot with a couple pieces of wire for a handle work for that? Seems like a quick way to get the big trash out.

[Steve Steven]

Galvanized hardware cloth is zinc coated, with a LOT of surface area, and will dissolve the zinc into the melt. Would rather see you use a non-galvanized screen mesh, which might be hard to find if you don't have access to an industrial source. Recommend a slotted spoon, cheap and easy to find in kitchen supplies.

Steve

[remy3424]

I was wondering if that could happen....might have to stick with the slotted spoon.

[leadman]

Expanded metal which is bare steel might be used for a basket to lift the debris out of the pot. Comes in many designs.

If the OP can melt at 650-675 degrees it would be better. Also many of the zinc weights do have ZN on them so this helps speed up the sorting. I use the side cutters only on suspect weights with no markings. The iron are marked FE.
I would be concerned about the smoke that comes from the pot leaving a dirty/oily surface on the inside of the oven. I do wash any wheel-weights I intend to smelt, helps with sorting and reduces the smoke.

[454PB]

So no temp answers huh????

Zinc melts at 787 degrees, wheel weights around 675 degrees. 700 degrees should work.