Proper Alloying of Lead and Antimony

[nicoariate]

Hi

This is my first post after lurking for a few years now. I'm trying to build a proper furnace to melt down and mix lead and antimony in bulk. I will be melting down range recovered lead and will be adding 2-3% antimony.

My current setup consist of big pot I bought at the local market which i think is made off aluminum or steel alloy. Bottom line, it doesn't break down once lead and antimony is melted lol. this pot goes on top of an industrial kitchen burner which is extremely inefficient as the heat dissipates easily. for a 45-50kg batch of lead and antimony, it take a few minutes after an hour to melt. Also, sometimes I alloy in tin. Most of the time, I don't. I also know for a fact that tin helps dissolve antimony faster.

Here are my questions which I hope you guys can shed some light on:

1. considering that I won't be adding in tin, what is the proper way to alloy lead and antimony? Should I melt them both on separate furnaces and then once completely melted, add in the antimony to the lead? or should I melt the lead, add the room temperature antimony in and mix it until it melts?

2. what I do now is that I melt the lead, add in antimony and mix it until melted. What I noticed is that antimony floats in lead which is probably the reason why I cast some batches that are inconsistent in weight. Is there some sort of technique or proper way if mixing melted lead and antimony instead of just stirring it with a big laddle?

I hope you guys don't mind this lengthy post as I am trying to be as detailed as possible.

[JimB..]

I don’t know the process, but alloying lead and antimony is not easy. Most casters add antimony by using clip on wheel weights, type setting lead (linotype, monotype), or buying a lead/antimony alloy from a foundry (Roto Metals, Superhard).

I also believe that antimony is highly toxic.

Please do not us an aluminum pot, it is very dangerous to do so as it will eventually fail all at once without warning.

[243winxb]

Pure antimony melts at 1167F degrees. To hot for lead alloy. I just add linotype. Rotometal make a SuperhardAlloy that would blend in at a lower temperature. 30%-Antimony, 70%-Lead.

Melt the antimony, then add to the hot lead pot?

[Burnt Fingers]

You don't have to melt the antimony to dissolve it in lead. No more than you have to melt sugar to dissolve it in water.

It helps to have small pieces of antimony and the right flux. If you have both those and can keep the antimony under the surface of the lead it will dissolve pretty quick.

[m37]

antimony is dangerous wear rubber gloves respirator and face shield

that said adding antimony is not that hard
I did this on a larger scale than you need to I made ton of alloy at a time

It should work better to add the tin first but I didn't want the tin separating during the process
you need to build a small weighted basket to submerge the antimony I have deep fryer baskets
with steel pipe welded on with steel bars inside the pipe for weight
I break it up into around 1/2 to 1inch chunks
you could use fine wire mesh and wire it to a steel bar
when I was testing fluxes that's what I did

The most important thing is to coat the chunks with a flux
I dissolve citric acid in warm water as much as it will take
once dissolved I have mixed with alcohol to dry faster
put in spray bottle spray chunks until wet
you could use all alcohol it just takes a lot longer to dissolve the citric acid

Instead of spraying them you could just dip them in the flux with the amount you are doing

put the fines and real small pieces in a small pan I used a ingot mold and get them wet
the flux is sticky when dry and will hold them together make sure these are dry
I put them in my big coating oven for a hour or so at 150f

I coat them a few days ahead to let dry and for the acid flux to eat on the antimony
if they don't seem too sticky I will spray them again

submerge basket in lead I will agitate /move the basket around in the lead it will bubble fairly strongly at first
this helps the antimony dissolve and the bubbles help lift trapped solids out of the lead
if you pull the basket up you will see the lead had "tinned" the antimony that's what makes it work
each basket has about 15lbs in it takes 10-20 min to dissolve at 650-700 deg

this was about a 2000lb pour with range lead that I added 4% antimony and some tin

per BNE
First Sample - Range Lead
Pb = 98.3%
Sb = 1.6%
Sn = 0.0 - Trace%

Range Lead with Sn and Sb added:
Pb = 93.12%
Sb = 5.65%
Sn = 1.2%
Cu = 0.03% (This is believable and consistent with other samples from range scrap.)

had to mix a few hundred lbs from a different batch of range lead that's where the Cu came from


mike