Thinning down Zinc contaminated Pb...?...

[OS OK]

I came across 120 Lbs. of Pb I thought was COWW's...as you can see, the ingots look fine...only problem is this, they are way too hard for WW's.
Assuming the extra hardness is from Zinc, Zn, alone...how much pure Pb would you mix with this 120 Lb. batch to bring the hardness down to an acceptable low pressure pistol Pb blend...say 14 BHN?

Attachment 194477This is a picture of 12 of the 24 ingots that I've tested for BHN. ^ It looks fine to me, no cottage cheese Zn excess here.

I don't have any experience thinning down contaminated Zinc/Pb...are there any other problems I may incur doing this?

*I think I've heard that Pb can tolerate a 5% blend of Zn...but not sure if that is correct.
*I don't have any idea either of what %'age Zn represents in BHN numbers.

Any suggestions you fellas have will be greatly appreciated...charlie

[Traffer]

You should have it tested for content. There is a member here under the name BNE who will test it for you. He asks for 1# of lead in trade for each tested sample. I thought I had zinc contaminated lead also. He tested it and found it was just high in antimony and tin. (which is good). Then you may find someone within driving distance of where you are that will trade you for softer lead.

I came across 120 Lbs. of Pb I thought was COWW's...as you can see, the ingots look fine...only problem is this, they are way too hard for WW's.
Assuming the extra hardness is from Zinc, Zn, alone...how much pure Pb would you mix with this 120 Lb. batch to bring the hardness down to an acceptable low pressure pistol Pb blend...say 14 BHN?

Attachment 194477This is a picture of 12 of the 24 ingots that I've tested for BHN. ^ It looks fine to me, no cottage cheese Zn excess here.

I don't have any experience thinning down contaminated Zinc/Pb...are there any other problems I may incur doing this?

*I think I've heard that Pb can tolerate a 5% blend of Zn...but not sure if that is correct.
*I don't have any idea either of what %'age Zn represents in BHN numbers.

Any suggestions you fellas have will be greatly appreciated...charlie

[454PB]

Maybe it's linotype, the ingots look nice and cleanly cast.

[OS OK]

I've already spoken with BNE about sending him samples. He kindly is going to oblige, his work load is heavy at the moment and doesn't have a lot of spare time.
I wanted to get done with the preliminary BHN samples to see if I needed to send multiple hardnesses to make sure.
All of the 24 samples average 20 BHN as a 'lot sample'. So I don't figure I'll need to send more than one or two samples for testing.

If it were high in Sb, Sn or if it were some type of Linotype I'd be tickled...I'd just set it aside to use to blend with for rifle casting...I'm fooling with the 8 x 57mm right now but have the .30/30, .30/06 & the .308W to do, the latter two I want to speed up a bit so hard is good.

The reason I'm assuming Zinc contamination is because the fella that smelted this batch thought he had used COWW's exclusively...I'm thinking a few, or a lot of Zn snuck into the pot.

[Dusty Bannister]

Is it possible that he used some type of cooling to speed up the ingot forming process? Quenching would get it quite a bit harder.

Not being able to examine the top of the ingot, I have to wonder if you filed it flat to be sure it did not give a false reading with the hardness tester. I know that you did not cast the ingots, but when I clean alloys, I use a large flat nosed bullet mold to cast sample ingots just for hardness testing. That way the sample is consistent and clean. I would suggest you test cast from one ingot and give it hardness tests every few days until your hardness levels out. Obviously, you have the hardness tester and it would only cost some time and then you would know if further testing is required or desirable.

[upnorthwis]

I would cast some up and shoot them to see if they are a problem. I'm thinking not.

[Freischütz]

Ibelieve I'd melt this stuff in a separate pot, see what the drosslooks like, and try casting a few bullets. If there's a contaminantI’d heat the metal just above lead’s melting point and then stirand skim to see how much contaminant would precipitate out.


Ithink there’s a thread here on decontaminating with sulfur. I’dtry things like that before throwing good metal into bad.

[JonB_in_Glencoe]

Zinc doesn't add that much hardness, maybe a point or two for COWW alloy with about 1% or 2%, any more Zinc than that, and you would have a devil of a time, even pouring ingots. Here are some Zinc contaminated COWW alloy.
http://castboolits.gunloads.com/show...ing&highlight=
I concur with others, that you have linotype ingots.

[Traffer]

Ibelieve I'd melt this stuff in a separate pot, see what the drosslooks like, and try casting a few bullets. If there's a contaminantI’d heat the metal just above lead’s melting point and then stirand skim to see how much contaminant would precipitate out.


Ithink there’s a thread here on decontaminating with sulfur. I’dtry things like that before throwing good metal into bad.

Yes this is a great idea. You can tell if it is weird by the way it melts and the dross that comes up. I have tried using sulfur to smelt out zinc. There is either a thread on it or a lot of conversation on a thread. It turns out that the alloy I was trying to smelt zinc out of didn't have any in it. lol. You can also try putting muriatic acid on it. If it bubbles it has zinc.

[OS OK]

Attachment 194496

Is it possible that he used some type of cooling to speed up the ingot forming process? Quenching would get it quite a bit harder.
I didn't ask whether he quenched or not...didn't even think of that because it wouldn't do any good to quench ingots because when they hit the cast pot they will come back to their normal hardness for the Pb blend you have. It could be that a dishonest smelter would try to pass WW's ingots for Lino by quenching but he would be found out in short order...nawh, he advertised COWW Pb, I don't think this figures into the question.

Not being able to examine the top of the ingot, I have to wonder if you filed it flat to be sure it did not give a false reading with the hardness tester. I know that you did not cast the ingots, but when I clean alloys, I use a large flat nosed bullet mold to cast sample ingots just for hardness testing.<(I can't test on a meplat, can't position the magnifying scope on the narrow meplat and focus it properly, I file the sides and test) That way the sample is consistent and clean. I would suggest you test cast from one ingot and give it hardness tests every few days until your hardness levels out. Obviously, you have the hardness tester and it would only cost some time and then you would know if further testing is required or desirable.

The tops of the ingots look as good as the bottoms just not as smooth as the bottom and side planes, as you see in the picture I test dimple on the bottoms of the ingots where it is smoother and more level than the top of the pour. The red is a Marks-A-Lot, it makes the dimple appear lighter in red color and very shiney and distinguishes it from the 'crater edge' of the dimple. Easy to get exact measurements with the LEE SCOPE.

These two ingots obviously came out of different muffin pans, see the radius on the bottom edge. The muffin pan on the right has a textured finish...don't mistake that for something wrong with the lead...for instance 'cottage cheeseing'.

[Taterhead]

By the way, if you need muriatic acid, go to a swimming pool supply store. So much of what is stocked at the hardware stores now is a "greener" type of product with a bunch of adjuncts. The stuff at the pool store is the real stuff. I use gallons of it every summer to balance ph in the pool.

[OS OK]

I would cast some up and shoot them to see if they are a problem. I'm thinking not.

I'll have to melt some of this Pb to get samples for BNE, he wants a specific size to test. I don't think this Pb blend will be a problem either with the fill out...but...I don't want a high %'age of Zn in the blend, I am afraid it will be too abrasive on the rifle bores...think about it...I have 120 Lbs. of this stuff. I want to thin it out as much as possible.

[OS OK]

Ibelieve I'd melt this stuff in a separate pot, see what the drosslooks like, and try casting a few bullets. If there's a contaminantI’d heat the metal just above lead’s melting point and then stirand skim to see how much contaminant would precipitate out.


Ithink there’s a thread here on decontaminating with sulfur. I’dtry things like that before throwing good metal into bad.

It doesn't look like I'll get around having to have this Pb XRF tested...I won't throw good Pb into the bad.
This is just a problem that I could get all 'twisted' over but I'm trying to use this mishap as a learning curve by fixing the problem. It's a win-win situation since the seller is bending over backwards to make it right.

[OS OK]

Zinc doesn't add that much hardness, maybe a point or two for COWW alloy with about 1% or 2%, any more Zinc than that, and you would have a devil of a time, even pouring ingots. Here are some Zinc contaminated COWW alloy.
http://castboolits.gunloads.com/show...ing&highlight=
I concur with others, that you have linotype ingots.

Those examples are glaringly obvious...it ain't my situation. I think I can have up to 5% Zn in the mix, I'm not sure...I wish r5r would put his 2-cents in, I think he knows something about Zn.

It would be a great help if there was a formula about Zn and how it adds to BHN value...that way I could better back-engineer this mess using a formula like this one.

Estimated hardness calculated by Rotometals formula: Brinell =8.60 + ( 0.29 * %Tin ) + ( 0.92 * %Antimony ) Only difference is I'd use 5 BHN for the Pb value...more realistic.

[OS OK]

By the way, if you need muriatic acid, go to a swimming pool supply store. So much of what is stocked at the hardware stores now is a "greener" type of product with a bunch of adjuncts. The stuff at the pool store is the real stuff. I use gallons of it every summer to balance ph in the pool.

Thanks, it's been a while since I maintained a spa, I forgot about that. I'm going to get the XRF measurement done so I can depend on some calculations about this mix.

[RogerDat]

Seem to recall bangerjim did some testing and below 5% Zn wasn't un-castable. if these are all running with a BHN near linotype I would set one in a ladle and hit an edge with a propane torch. Not easy to mistake that lower melting and smoother flowing nature of lino for zinc.

Might be a case of I think I only cast those with.... when in fact he had something else but forgot about it. Sometimes I forget the composition of the block in my hand going across garage. If not marked when made it could be anything. Drain cleaner with muratic acid would rule in or rule out zinc. Don't have to keep a gallon jug around that way.

[OS OK]

Casting (Zinc Wheel Weights) Into INGOTS = BULLETS
Casting 300 BLK. "ZINC" Bullets! Lead Alternative?

elvis ammo on YouTube did the Zn casting and believe it or not...they didn't come out half bad. They are just hard as can be! Hard as a '_____'s - heart'.
I think he said the 250 grain 300 Blackout cast would weigh 130 grains. The astonishing part is this...they measure 37 BHN as pure Zn!
This is one instance when you can't cut the sprue fast enough...otherwise you'll have to beat the heck out of the mold to cut those hard sprues.

[OS OK]

*If the XRF test comes back telling me that Zn is the contaminate...

Do you fellas think that using this old mixing cross would give me the correct ratio/weight of soft Pb to use to blend the 20 BHN down to say...15 BHN?

EXAMPLE of MIX CROSS . . . . . . . . . >Attachment 194509
Applied like this....?

Attachment 194510
Do these figures look correct?

[Bird]

OS OK. Melt the ingots in your pot. Take the temperature to 600 and hold it there.. If there is any zinc in the mix, you will see it on the top of the melt. Try casting a few at 700 to 720, and if the melt starts sticking to the sprue plate, then you know there is zinc in the mix. If you are using iron molds, the bullets will tend to stick in the mold if there is zinc.
I think you may have linotype lead.
Your figures look correct and will get you close to 15 bhn, but may come out slightly harder though.
If there is zinc in the mix, get most of it out before blending in the pure lead or you can still end up with casting problems. Do a search on my posts, and you will find out what happens if zinc is there.
Here is the thread to read. http://castboolits.gunloads.com/show...with-alloy-mix

[JohnH]

I don't think it's zinc, I think it's linotype. I have some linotype pigs (25 pounds) I normally mix them at two parts lead to lone part linotype. This makes an alloy that is for practical purposes wheel weight. Linotype mixed one to one with lead gives you Lyman #2 alloy @15 BHN.