Antimony separating

[nonferrous]

I have tried adding a few blocks of Monotype to the casting pot and could not get the antimony to flux into the melt, it wants to separate.
I tried it another time with a few sticks of Linotype, thinking that because it is not so rich, it may blend better, same result.
I have done some reading and can't seem to find anything that addresses this. Monotype and Linotype melt at a lower temp that lead, it would seem that when they all go liquid, they would blend, they don't.
What looks like must be done, is that the alloying should be done in advance during the smelting stage.
Is it necessary to bring the melt up to a higher temp during smelting, like 1000 or so to get these elements to blend, then ingot, then into the casting pot?
Any help would be appreciated.
Thanks

[cbrick]

Interesting, mono should be at liquidus at 512 degrees. The only thing that comes to mind at the moment is what kind of flux are you using? It could be possible that your flux isn't reducing the antimony. What temp were you doing this?

I've never tried alloying with mono, kinda tough to find but keep us informed, always good to learn something new.

Rick

[runfiverun]

try using a carbon type of flux.
take yor temp up to 700 or so and flux then. the antimony is probabaly showing itself as a grey bubbly type on top of the pot right?
just flux and stir it back in.
i have alloyed antimony itself in at 610* with marvelux and a lot of patient stirring.
sawdust,ashes from the wood stove. charcoal briquettes crumbeled up,etc...and a paint stir stick should put it back in.

[lwknight]

I know that when I melted some of Rotometals 30% "Superhard" it was slushy at all temperatures. I was thinking that if I used the bottom spout that I might drain some lead out of the slush.
So I just shoved in a ladel and stirred it and ladeled it into smaller ingot molds.
When the pot got too low to ladel out the last,I just put on gloves and poured out the pot
It all worked out just fine.
The high antimony stuff will trick you though. It will look like its set up and when you dump the mold it will run out some lead and deform the ingot.

[sagacious]

The chemical and physical processes that occur during alloying are not like simply mixing whisky and soda.

Just because the monotype/linotype/etc and the base lead are both liquid does not mean they will mix immediately and completely like some other miscible liquids. It's more like adding sugar to water-- the process is accelerated by thorough and patient stirring, as suggested in another reply above.

Fluxing and stirring are your friends here. You gotta flux and stir until it's all blended. Keep stirring, and you'll get there.

Good luck, hope this helps. :drinks:

[Casting Timmy]

I don't think it's the fluxing that will matter so much as the temperature. You'll need to raise the temperature of the melt so that the antimony can melt into it. I have an old book and it talks about smashing the antimony up with a hammer into smaller pieces. This will make it a little easier to melt in, if you can bust it up a little. Once you get the antimony alloyed it will have a lower melting temperature. The other thing the book suggested was using a propane torch up top to help melt the antimony in and it said not to flux during the process, just keep adding in more antimony and lead until it was all melted.

I don't think mixing metals is a chemical process, it's more of a physical process. Lead and tin are two metals that are completely soluble, if you look at a lead/tin phase diagram you can see how at different temperatures between the liquidious and solidous lines you will have a mixture of liquid and solid. Both of these will be at different mix ratios than when the melt was above the liquidious line. There are exceptions to this rule, and that's an eutectic alloy. An eutectic alloy will always go from liquid to solid at a specific temperature. Electrical solder is a good example of an eutectic alloy, it goes from liquid to solid when it crosses a specific temperature. Solders for filling or repairing usually will have an alloy that goes through a mixture phase so that you can fill cracks or build up solder on the joint. This is possible because it will be slushy and hold it's position better when between the liquidious and solidious temperatures.

[Linstrum]

Sagacious and Casting Timmy are on the right track, but there is another process that should also be considered as a likely culprit :bigsmyl2: besides simply re-combining slowly. Monotype is 74% lead, 16% antimony, and 10% tin, and there isn't any problem combining this alloy with any other lead-based alloy containing the exact same metals in different proportions.

Lead, tin, antimony, copper, bismuth, and arsenic are always soluble as a group in the amounts used for our purposes, they are not fickle, [smilie=w:being soluble one day and then not soluble the next day.:veryconfu They are always soluble, and if there is a sudden problem getting them together then you need to look for what is causing them to either separate or not dissolve to begin with.

If you can't get two batches of lead-based alloys to mix (such as Linotype or Monotype with wheel weights) or have trouble with their constituents separating out, please be patient and read on:

A very common silver ore is a mixture of lead sulfide and silver sulfide. The lead/silver ore is called galena, which should be a very familiar name [smilie=s:to everyone here. Silver metal and lead metal are totally miscible with one another in the ratios that they occur together in natural ores, and the two cannot be separated by melting and then expecting the very slightly lighter silver metal to rise to the surface where it can be skimmed off like cream from milk. It doesn't work that way.

In 1850, a clever British metallurgist named Alexander Parkes developed a very simple process for making the silver separate out of the melt and float on top of the lead, where it could be easily removed. What Parkes discovered was that when zinc metal is added to the molten lead and silver alloy that the silver metal is selectively dissolved out of the lead by the zinc, which is only slightly soluble in lead. The new zinc and silver alloy floats to the top of the lead and is poured off. Next, the zinc is removed from the silver very, very simply by distillation since quite amazingly zinc boils at red heat and turns into a gas that can be thought of as "zinc steam". The zinc vapor is condensed back to its solid form by cooling it and then added back into a new batch lead/silver alloy so the process can be repeated to recover more silver from lead.

The same process using zinc as a selective solvent works with other metals besides lead and silver; antimony and copper can be separated out of lead using zinc in the exact same manner as using zinc to separate silver from lead. Since zinc is now a common but accidental contaminant :groner: of our lead supply, I would suspect that zinc contamination is the culprit since it only takes a very tiny amount of zinc to combine with the non-lead constituents in a casting alloy and float out on the surface, giving the appearance of something not dissolving like it once did.:confused:


rl669

[nonferrous]

When this occured I was at 700 degrees and fluxing with paraffin wax and a pine paddle.
The Antimony floated in the form of silver slush and did not want to go into solution with the lead, even with quite a bit of stirring, I skimmed it off and saved it.
What linstrum said regarding Zinc contamination separating the metals could have some merit, as I am sure that I skimmed off more slush than the Monotype I added.
However, I have cast from this same batch of clip on ingots and the result of fluxing was a very thin layer of soot on top of the melt, almost to thin to skim.

Thanks

[felix]

All above is true. The best we can do at home is to never throw anything away except the thin soot. The hard stuff from the casting pot should be thrown back into the smelting pot, in our situation that would be the MOAS for another year's worth of melt which includes several buckets of WW, range scrap, et.al. Then the "****" would be such a small percentage in an ocean of other stuff which go readily into "solution" already. Because there is so much "solvent" the **** will enjoin the solution as constituents. However, there is no guarantee that any batch of lead using this process will deliver perfectly shooting boolits. ... felix

[1874Sharps]

Gentlemen,

Thanks for the great information presented above. It was very educating and interesting! It is nice that this forum has some members with metallurgical knowledge.

[sundog]

My last two batches of boolits, one Sunday past, and one yesterday, were both of WW and range scrap ingots. Both batches got 'pop corny' on top. A paraffin flux followed by another fluxing with wood ash got it mixed back in. The ash was purposefully submerged with the spoon and stirred. The ash remained on top as an oxidation barrier. This is normal routine for me. From my experience, both heat and carbon flux are required to get a good mix. If the pour is not good I would suspect a contaminant, possibly zinc first. The other culprit for me in not getting a good pour is to high percent of copper as it tends to freeze to quickly when ladle pouring, works better with a dipper when there is no air contact between dipper and cavity. More often than not copper problem is self induced, but 'thinning' the alloy with more WW and/or range scrap lowers the copper content.

One of our board members not to long ago also addressed sulphur as an alloying agent. That makes sense to some degree because of galena in its natural state. What I never found out was if the sulphur had adverse affect on casting equipment or barrels.

[StarMetal]

My last two batches of boolits, one Sunday past, and one yesterday, were both of WW and range scrap ingots. Both batches got 'pop corny' on top. A paraffin flux followed by another fluxing with wood ash got it mixed back in. The ash was purposefully submerged with the spoon and stirred. The ash remained on top as an oxidation barrier. This is normal routine for me. From my experience, both heat and carbon flux are required to get a good mix. If the pour is not good I would suspect a contaminant, possibly zinc first. The other culprit for me in not getting a good pour is to high percent of copper as it tends to freeze to quickly when ladle pouring, works better with a dipper when there is no air contact between dipper and cavity. More often than not copper problem is self induced, but 'thinning' the alloy with more WW and/or range scrap lowers the copper content.

One of our board members not to long ago also addressed sulphur as an alloying agent. That makes sense to some degree because of galena in its natural state. What I never found out was if the sulphur had adverse affect on casting equipment or barrels.

Corky,

I'm not a metallurgist, but worked at a chemical plant that's sole product was insoluble sulfur. Very few pieces of equipment were made of stainless steel. The rest were plain steels. Never was there any corrosion or wear to any equipment due to the chemical natural of sulfur. You know that sulfur is used in making certain steels, some they add sulfur, some they try to take the sulfur out.

At any rate speaking about barrels, I would imagine any sulfur transferred to it by the alloy bullets would be very minor. The casting equipment I wouldn't so much be worried about as it's easier to replace then the barrel. Now if sulfur had a very bad corrosive effect on metals I'd be concerned about the melting pot developing a hole.

Joe

[sundog]

Good point about the pot, Joe. Catastrophic failure would be, well, catastrophic. It would ruin your day, too. Seems like once the sulfur was tied up in the mix, it would mostly stay there. Same here, not a metalurgist.

I kinda remember the point being made about sulfur was use as a hardening agent in lieu of antimony when quenching or heat treating. I have a unused, small steel pot, so perhaps I should try some.

[montana_charlie]

I would suspect that zinc contamination is the culprit since it only takes a very tiny amount of zinc to combine with the non-lead constituents in a casting alloy and float out on the surface, giving the appearance of something not dissolving like it once did.
That is an interesting fact. I wonder how much more involved the process might actually be.

If it is truly that simple, a guy in need of 'pure' lead could melt down a batch of wheelweights, add a zinc one at a temperature high enough to melt it, and scrape off the crumbly scum that appears.

If he tested the resulting metal for hardness, he would have some idea about whether it worked.

Any of you w/w guys interested enough to give that one a try?
CM

[cbrick]

I kinda remember the point being made about sulfur was use as a hardening agent in lieu of antimony when quenching or heat treating. I have a unused, small steel pot, so perhaps I should try some.

If I remember correctly it was sulphur used in place of arsenic as a catalist in HT lead/antimony alloys. There are several materials besides arsenic that can do this but arsenic is mostly used throughout the metals industry.

If you try any experiments with sulphur I'd sure be interested in your results.

Rick

[cbrick]

That is an interesting fact. I wonder how much more involved the process might actually be.

If it is truly that simple, a guy in need of 'pure' lead could melt down a batch of wheelweights, add a zinc one at a temperature high enough to melt it, and scrape off the crumbly scum that appears.

If he tested the resulting metal for hardness, he would have some idea about whether it worked.

Any of you w/w guys interested enough to give that one a try? CM

I dunno Charlie, Linstrum mentioned "red hot" and "zinc steam". This could be quite the complicating factor in a casting pot, :-( not to mention possibly a bit dangerous.

Rick

[StarMetal]

Good point about the pot, Joe. Catastrophic failure would be, well, catastrophic. It would ruin your day, too. Seems like once the sulfur was tied up in the mix, it would mostly stay there. Same here, not a metalurgist.

I kinda remember the point being made about sulfur was use as a hardening agent in lieu of antimony when quenching or heat treating. I have a unused, small steel pot, so perhaps I should try some.


Corky,

Some more interesting things about sulfur was it was very difficult to prevent it from leaking through flanges and valves. Sulfur also doesn't shrink when it cools from a liquid. Could use it for a chamber cast, but it's very delicate. We packaged 50 lb bags of powdered sulfur and because the statie electricity was so high in the winter in PA some of the baggers (personel, not the machine) had to be grounded to the floor. We had many explosions and fires because of that stuff. The material was used exclusively in vulcanizing rubber. But as I mentioned I didn't see any evidence of deterioration in the machinery due to the sulfur and I had to work along with maintenance as I was the Process Operator.

Joe

[montana_charlie]

I dunno Charlie, Linstrum mentioned "red hot" and "zinc steam". This could be quite the complicating factor in a casting pot, :-( not to mention possibly a bit dangerous.
Yeah, but...
That was in order to separate the zinc from the metal it removed, and recapture the zinc so it could be used again.

I think one of us would just dump the crumbly scum, and grab another zinc w/w out of the bucket...
CM

[lwknight]

Nonferrus, what I was trying to tell you is that the slush is the high antimoy content. Of course my 30 percent was too much to cast with. I was just describing the slushieness.
Even when you have lino, it will have some slushy stuff trying to get floaty and like others said, just keep it fluxed and stirred.

I actually got some zinconated stuff and its no doubt when it really happens.
Its like thinking you see a deer and when you really, you know it.

As MuddyCreekSam mentioned in another post. " A few drops of muratic acid will boil and turn all kinds of colors if zinc is peasent.

[sagacious]

Nonferrus, what I was trying to tell you is that the slush is the high antimoy content. Of course my 30 percent was too much to cast with. I was just describing the slushieness.
Even when you have lino, it will have some slushy stuff trying to get floaty and like others said, just keep it fluxed and stirred.
...
This is the fix. If you work with the various type metals, you will invariably see this "slushiness" eventually. It can be overcome by fluxing and stirring.

Note: Fluxing does not just remove impurities. It definitely also facilitates the mixing (alloying) of metals. It does this by removing/reducing the oxide layers; by decreasing surface tension; by preventing oxygen from reaching the alloy components, etc.

Hope this helps, good luck.

[sagacious]

...
I don't think mixing metals is a chemical process, it's more of a physical process. Lead and tin are two metals that are completely soluble, if you look at a lead/tin phase diagram you can see how at different temperatures between the liquidious and solidous lines you will have a mixture of liquid and solid.
...
Just as a point of interest, and not to be contentious, the opinion quoted above is a commmon misapprehension.

The components in an alloy may combine both physically and chemically. One cannot get more than a vague grasp of the lead/tin phase diagram and the eutectic point unless one understands that chemical bonds are involved.

Here's an analogy that may help explain it a little better:
In 'homogenized' milk, one finds a physical mixture of water and tiny globs of fat. But the globs of fat are actually composed of a different elements chemically combined. One finds something similar in many lead alloys-- a physical mix of chemical compounds.

When lead/tin solder bonds to a copper pipe, for example, it does so chemically. The lead/tin alloy chemically combines (alloys) with the surface of the copper. Soldering almost always requires a flux, because the reducing action of the flux facilitates the alloying of the solder to the copper. The same sort of thing happens in your lead pot.

Fluxing is very important when combining and homogenizing a lead alloy melt such as when adding monotype alloy to a pot of ww lead or other lead alloy. Not fluxing properly can lead to any number of problems. When working with lead, fluxing is your friend. Fluxing with hydrocarbon flux will never 'damage' an alloy, nor prevent combination of constituents within a lead alloy.


The other thing the book suggested was using a propane torch up top to help melt the antimony in and it said not to flux during the process, just keep adding in more antimony and lead until it was all melted.
This will help when adding pure antimony to lead. The torch flame does not only locally increase the temp of the melt at the surface (where the chunks of antimony are floating), but the flame also provides a reducing atmosphere during the alloying process. That helps a lot, and the reducing action there is the same function that fluxing provides (if you light the smoke during fluxing, you get the benefit of melt surface temp increase and also a reducing atmosphere). This is not just trivia-- this knowledge will definitely help anyone working with lead alloys.

Hope this helps, best of luck! :drinks:

[montana_charlie]

Thanks, sagacious.
A recent experience caused me to slightly modify my general understanding of 'fluxing'.
Now, I know why...

CM

[nonferrous]

Thanks,
I have no doubt that the silver slag was antimony and I saved it to smelt back in the next batch of ingots.
A while back, within a thread similar to this on alloys, a member revealed what he believed to be the combination of metals that created the best alloy for most boolit casting.
His formula was this, simply blend 50% of clip on WW's that you got for free and combine them with 50% of clip on WW's that you had to pay for, then flux and cast. I have had very good luck casting with this method.
However, a while back I inherited 3, 50 pound ingots of mystery lead that I believe is boat keel salvage. I have also piled up over 100 pounds of stick on WW's from sorting and some dive weights.
I bought 50 pounds of Lino to mix with the pure to try to get the Antimony and Tin up a little. The very next week a friend asked me to get rid of some lead that was in his garage, I went over to get it and it was 100 pounds of Monotype.
I am now convinced that the casting pot is not the place to add the type metal. My next attempt will be to fire up the smelter and see if I can blend the pure and Mono about 6 to 1. All I can do is to flux and stir the devil out of it, try to get it into solution and pour ingots.
If this goes ok, then see if they stay in solution in the casting pot.
Thanks again