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Thread: A possible way to remove zinc from molten lead

  1. #61
    Quote Originally Posted by nwilson1024 View Post
    i have been looking over this thread the past few days and I had an idea that popped into me head today. This is a little excessive and time consuming but I think it just might work. I mention this to try and spark ideas from others.
    So as stated HCL will react with the zinc and not this lead. This we know. The problem becomes that we have ingots and dunking them into CHL will only treat the surface area of the slabs. My thought was to make as much surface area as possible then treat the mix in HCL.
    If one were to melt the mix to liquid form and take a ladles worth at a time and CAREFULLY toss it onto a cooler surface (like a piece of sheet medal) the mix would harden almost instantly. This would create much more surface area for treatment in HCL and much less area that would be shielded from the HCL. You would just gather all of these thin pieces of mix and drop them into HCL and let the zinc bubble to hydrogen leaving only the lead and other alloys behind.
    I realize this would be time consuming, and might not even work that well, but like I said just trying to spark some thought.
    The process is done by slowly and in a very thin stream, pouring the molten metal into a pail filled with ice cubes. HCl will dissolve the zinc, but it will make a very big mess of the lead forming lead choloride. That's a big mess to undo.

  2. #62
    Quote Originally Posted by GunStuff View Post
    From a chemistry point of view the zinc is a much more reactive metal than are the others mentioned. The electromotive series is a relative scale that lists elements from most reactive to least reactive. Here is the list starting with zinc: zinc>chromium>iron>cadmium>cobalt>nickel>tin>Lead>hydrogen>antimony=arsenic=bismuth>copper. While sulphur may react with a small amount of the tin and lead, it will largely react with the much more reactive zinc metal.

    The suggestion to separate the zinc weights from the lead weights should be done first. Then separate out any zinc that slipped through by adjusting the temperature of the pot to melt the lead but not the zinc which will float on top. Finally, eliminate the residual zinc with the sulphur treatment. That should leave you with an alloy/lead containing very little zinc.

    The melting points of pure metals: lead 327.3ēC , zinc 419.5ēC, steel ~1375ēC The specific gravity of pure metals (how heavy they are compared to the same volume of water) lead 11.3, zinc 7.1, steel ~7.7 . That's near room temperature. At a higher temperature the numbers change a little but both solid zinc and steel (the cllps) will still float on liquid lead.

    No one has suggested distilling the zinc off. It could be done as zinc boils at 907ēC while lead boils at 1750ēC. OK, that's a stupid suggestion but it's fun to throw it out there for the back yard distillers to contemplate.
    Something similar is used in refining. Zinc is added in the refining process. Gold and silver are very attracted to lead, much more so than the Iron sand in which they are usually found. Zinc s added in the molten state after the iron is removed and melted in, as zinc is around 3000 times more attracted to gold and silver than to lead. The zinc then forms a dross on the top as the pot cools, and is skimmed off. Then the zinc is then boiled from the silver and the gold and recovered for reuse... Charcoal or coke is used to rid the lead of the zinc.

  3. #63
    Boolit Man
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    RE: Sulpher

    PLEASE111 WATCH THE FUMES. They can be quite toxic. I stand with my fan behind me and blowing fumes away.

    Lump S is hard to find around here, so I went to my Druggist (a shooter) and bought some "flower of sulpher

    Good Luck!




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  4. #64
    Boolit Master
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    if you guys care I have found 5 pound bags of powdered sulphur for like 10$ in the hunting section at canadian tire. For deer I think? No clue why. Maybe you could find some in hunting stores.

  5. #65
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    Quote Originally Posted by Markbo View Post
    This is a repeat of a post in another thread: I think the problem is using a Propane turkey fryer, the temp gets above 600° whether I plan on it or not. Think of a 2/3 propane tank - my smelting pot - almost full of wheel weights. By the time the liquid is visible or enough that it floats what's on top of it, that temp in the bottom (and yes I do use a top) has exceeded zinc melting temperature.
    I have had one batch fail doing that. I filled the pan, cooked, everything melted in an ugly slush. I did the cooling and heating skim, lots of fluxing, removed probably 95%....

    What I did before, and now do, is start with just an inch layer in the bottom. let melt, skim. add an inch of weights, let melt, skim.
    I don't separate weights now. I just add a bit and skim, keeping the mix just above lead melting temp. zn doesnt melt. just skim off with clips.

    Works 100% easier for me.

    Separating is a hassle, takes hours and hours, and I STILL got some zn that wasnt identified in the mix. I just skimmed off.
    faster imo is just to dump more into the mix, re-heat to liquid, skim off, ... keep going.

  6. #66
    Boolit Bub
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    Quote Originally Posted by sciguy View Post
    I believe that matches and road flares have an oxygen providing compound as one of their ingredients. You would be amazed how quickly a huge number of materials would combust when mixed with a good provider of oxygen.

    Hugh
    Not sure if road flares have any sulfur at all but they do have a lot of Strontium nitrate and wood meal. The wood meal provides a fuel and the Strontium nitrate is an oxidizer and colorant. It makes the flame red. I do believe there is pvc included too as it makes the color brighter and more red.

    Frank

  7. #67
    Boolit Master


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    For all those that proclaim the simplicity of Just Keeping The Temp Below the melting point of zinc, it aint that easy.
    If we only used a heat source that produced less than 725 degrees, we would take forever to melt even pure lead. The flame licking the pot is measured in thousands. The heat transferred through the pot is also measured in numbers way over the zinc melting temp. If just a single zinc weight was missed and happened to be against the pot, under the weight of all the lead above it, guess what happens to it. It melts. It is melted before even 5% of the lead.
    Getting the zinc out of a melt is iffy at the very best. Keeping it out of the pot to begin with is the answer.
    It takes less time to pinch everything, than to look for the symbols or fishing out (hopefully the only) floating Zn weight. It makes no sense to collect, half look, and melt contaminated alloy. Either do it right or pay someone else, and hope they did it right.

  8. #68
    Boolit Man
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    I went to the Sanders Lead Company in Troy, Alabama a few years ago. They have an industrial tower/bui9lding that looks like a cracking tower found in oil refineries. One of the Engineers told me that they bring in scrap lead and then heat it up to 2300 Degrees Fahrenheit and separate ALL the various metals from the lead.

    They sell their pure lead in 60 pound ingots and will actually give you a computer print out of all the metals in it. Their "Pure" lead is around 99.96% pure if I recall correctly.

  9. #69
    Boolit Mold
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    I had an occasion once to try to separate Sulphur from Bentonite Clay and use the Sulphur in making Black Powder. Filled a gallon jug (big lid) 1/2 full of water and added the Feed Store bought Sulphur until the mixture was fairly thickened. Then you shake the jar for a while then let it settle. The Sulphur goes to the bottom. Then dip out the remaining water and clay down to the Sulphur. You will probably take out a little mix of both products. Pour out the Sulphur in a large pan that is tilted a little. The water will drain and can be picked up with paper towels. Let it completely dry and you have usable Sulphur.
    Last edited by OldBearHair; 06-11-2015 at 02:29 PM. Reason: mis-spelling

  10. #70
    Boolit Man AllanD's Avatar
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    I am constantly mystified by the fact that most casters are worried about Zinc, but unaware that during commercial refining of lead that it is intentionally mixed with molten zinc...This is because in mining and refining lead, the lead is essentially pure profit.
    How you ask? the SILVER (and there is typically a small amount of gold found as well) that is always mixed into native lead pays for everything!!!

    Read up on the Parkes Process (https://en.wikipedia.org/wiki/Parkes_process) for an understanding of the chemistry involved...

    I recall there was another process for separating zinc from lead or tin using copper sulfate but I would be hesitant to use the commonly available Copper sulfate... as those pretty blue crystals are not something you want to be adding to a pot of molten metal without expecting a visit from the tinsel fairy...

    Those pretty blue crystals are more technically known as "Copper sulfate Pentahydrate" (make thyself familiar with the
    term "water of crystallization")

    OldBearHair, Sulfur is not chemically important in black powder mixtures... it's function is more as an "Emulsifier" to aid even granulation. Black Powder is essentially a fuel/oxidizer mixture, the charcoal is the fuel and he Nitrate is the oxidizer...
    Last edited by AllanD; 07-31-2015 at 06:01 PM.

  11. #71
    Boolit Master popper's Avatar
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    Just don't push those pretty blue crystals under the lead until they turn white - the H2O is gone then and no tinsel fairy. Safely dispose of the brownish powder dross - wear a painters mask when handling the dross. It is a fine powder that is not good for you. Sulfur burns very well.
    Whatever!

  12. #72
    Boolit Master
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    Sulfur does the job... Which Kind?

    Well.... has been a long while since i 'revisited' our sticky collection... a long time....

    Removing zinc is an issue for good mold fill out. The best way, is to keep it out of your smelt pot. Browse through you smelt material and remove suspect WW's and other items. KEEP THEM....but smelt them alone in another batch of smelt.

    When I am smelting 'bad news' stuff...which, really, is most of the time.... I too start with sawdust AND ELEMENTAL SULFUR mix. It is easily found at the nursery, in small bags...about 4 or 5 bucks each. Watch closely as at the end of the year,,,in autumn, you can find 'hard' packages on sale...left out in the rain and they get real hard and caky. No issues here... cloth rag and a hammer renders the 'brick' soft enough for my smelt pot.

    I cover the bottom of my smelt pot with about 2 or 3 inches of sawdust mixed heavily with the sulfur. Or, a handful or two of sulfur. then I add my smelt material over the top.... then fire up the heat...on LOW... My smelt is usually,,,well...damp.... I water wash all my smelt item on the driveway the day before...wash out the mud, butts, trash... and let it stand over night if no rain in the forecast. I scrap it up the next day...dump in smelt pot a prepared as above...turn on the propane fire on LOW... So now...we are ready for TOXIC SMOKE..TOXIC FUMES...smoke like crazy and of course am OUTSIDE and now...we put on our safety gear...leather boots, Apron, sleeves..welding gloves, safety glasses and face shield....

    Are we now beginnig to see the SMOKE..FLUE GAS...smell the sulfur?? let it go and stink!! (expect love letters from your HOA!) come up a bit on the heat...little by little....when you see some melted metal...with a long handle spoon...face to the side...stir...slowly...keeping your head BACK and I slip on an acid gas canister mask here too. Come up on the heat....add some more FLUX....still slowly.... let that sit and stinks about 30 minutes....stir...mix...come up on heat and wait.... let things 'cook down'....and NEVER,,<EVER...add any more smelt material to the pot...NEVER.......So by now we are a good 90 minutes in our smelting operation and the pot is all molten...scrap out clips and dross... sides of pot and bottom.... and check temp of smelt...should be around 600 to 700....not too hot... and now...add final flux of sawdust and sulfur.... get back...gonna STINK....still,,scrape...remove dross....

    Once the smoking has slowed down.. and dross and grud are gone.... I finish with wax... I grabbed some toilet bowl wax rings a few months back and they are great.... stir...remove dross.... Bingo... I am ready to pour ingots.... I do not cast boolits out of the smelt pot....

    the trick here gents...is fluxing and coming up slow on the heat in the pot...keep in mind...my smelt was water washed last night... I do get some popping but to date... because I come up so slow on the heat....not tinsel fairy...KABOOM.... and the burning flux helps remove moisture....

    I never have tried the muratic acid trick...however I have heard the results are good. the magic stuff is the sulfur and I think the dry kind in my sawdust is safer. And I am very queasy about adding any liquid to my smelt pot. Once my pot is full... the only thing I add is dry sawdust and dry sulfur and wax....

    So...again...that's my 2 cents and worth every penny!!

    Nose Dive

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  13. #73
    Boolit Master
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    who ever said to put muriatic acid in the melt?

  14. #74
    Boolit Master
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    Triggerhappy 243..... Adding acid to our pots... muractic...sulfuric is discussed in the post shown below on this site. one below this one.

    http://castboolits.gunloads.com/show...-Sulfur-Report.

    The sufuric adds the sulfur...does about the same job if you know when, where, how to get it in the smelt pots safely. I don't do it. Powder sulfur does the same job and is safer in my opinion.

    Nose Dive.

    Cheap, Fast, Good. Kindly pick two.

  15. #75
    Boolit Bub
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    OK Hold it right here. The muriatic acid in the above web site was suggested as a way of checking a mix of wheel weights to see if any zinc ones are present. Yes zinc would react as opposed to lead BUT all of the iron clips in the mix would also react. Adding Muriatic acid was NOT suggested as a way of removing zinc from a lead alloy containing zinc. It was a stupid suggestion coming from a physics teacher with obviously no clue of what is in a bucket of wheel weights.

    Muriatic acid is a water solution of hyrochloric acid (HCl). In its anhyrous form HCl is a gas at room temperature. You be the judge if the water or HCl will stick around until the lead melts.

  16. #76
    Boolit Master
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    Who's on first?

    GunStuff... Mmmmm My response was targeted to the question---"who ever said to put muriatic acid in the melt?"--- (see the word 'who'?)

    My response was..to see the post...on this site that discusses adding acids, bases, plumbing solutions, to our smelt pots.

    Triggerhappy243, you, any reader can go to the thread, (again shown below), to see "
    who ever said to put muriatic acid in the melt?"

    http://castboolits.gunloads.com/show...-Sulfur-Report.

    The need, the usability, the desired results, the reactivity, and applicability of adding these solutions to our smelt pots was not questioned.

    Where to find the "WHO" was the response. I believe, if one reads the thread, one can discern the 'who'. And, I am sure there are other locations where adding reactive solutions to smelt pots is discussed. And, there too, the WHO, to me, would be important. As, an unskilled or neophyte smelter could be lead to concoct a mixture in his pot that could lead to one harming ones self and/or others.

    Your briefly stated analysis of the thread and the Chem 101 lesson in the reactivity chain, may or may not be astute. Again, only the individual reader can be charged to ascertain if the provided data is useful to his specific application.

    Nose Dive

    Cheap, Fast, Good. Kindly pick two.

  17. #77
    Boolit Master
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    In some of my melting of ingots from smelting, I get some less than BB sized balls that are shiny floating on the top of the melt. The lead temp is 715F. Should I try to flux those tiny balls with beeswax? There are only one or two when adding several 1 lb ingots to the melt.

    Ed C

  18. #78
    Boolit Master
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    edctexas... In my opinion, in your casting pot I assume, the wax trick my indeed help get rid of the little BB's. Depends on what they are.

    When I see 'things' appearing in my CASTING pot, I swish a bit with wax and see what happens. Rarely do i see 'particulate' matter appear in my casting pot, but, I do as a routine add WAX... I am not that exotic to add beeswax to my casting or smelt pots as to me, it is a bit out of my budget. I use any wax I can get my hands on to flux or reduce nasties in my pots. I save the beeswax for my mix for lube. And, I do not add my sawdust flux to my casting pot as I try to keep it somewhat clear and clean. If I find I have a 'bad smelt' ingot in my casting pot,,,,which indeed is quite often as I smelt a lot of 'road trash' and corruption.....I just pour the stuff out of the cast pot back into ingot mold to be 'resmelted' as discussed below....

    You didn't mention how aggressive you are in fluxing and mixing during smelting. Here, during smelting, is where i get 'happy' with sawdust and sulfur mixture to mix in my smelt pot. Usually do this three or four times at least. Mixing well all the time and at the temps you show. And, in the smelt pot, i always finish with a good dose of wax. I scavenged about 15 or so wax toilet rings from an apartment demo site back during the summer. After the top floor was demo'ed, i went back and got about 25 more from the ground floor. I also get some drippings from a church. They burn alot candles and don't mind me gathering the drippings. Wife burns scented candles and I always get some 'left overs' out of the bottom of those candle jars. I also find some form garage sales and Good Will. There, i gather a few pieces and offer about 50% of the total 'asking' price. Rarely am I turned away as I have cash in hand.

    Now beeswax is a better material that I 'pay for'. That is, give green money for it. This is used for my boolit lube mix. I deem it 'expensive' and keep it out of smelt and casting pots. My lube recipe is sweet enough to be blended on the kitchen stove or a hot plate in the shed.

    I would suggest you go to HOBBY LOBBY and get some wax blocks....the ones they sell to 'candle makers' ....this way, you are paying for wax and not 'candles' made by wage earning person's that you have to pay for.

    Give it a shot. See what happens. And then let us know how it went.

    Nose Dive.

    Cheap, Fast, Good. Kindly pick two.

    PS: if you flux with sawdust/sulfur, be sure to read on this site how, where, when to do this. SMOKES LIKE HECK..STINKS...and fumes are 'BAD NEWS" and must be done outside.
    PSS: one last suggestion...DON"T flux with sawdust/sulfur on a nice Sunday after noon in your back yard while neighbors are outside Bar-B-Quing. YOU will be told very quickly 'where to go'..and be queried by several citrus questions posed as to the degree of your intelligence. (ask me how I know)
    Last edited by Nose Dive; 12-07-2015 at 06:40 PM.

  19. #79
    Boolit Master
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    Boy this is an old one. I didn't read the whole thing so if this has already been sorry. I smelt my lead and turn it into ingots. To smelter it I use the melting point of the lead. I think it was something like 650*. The zink will not melt that cool so it floats to the top and is skimmed off. Same with the WW clips. Only place I've found zink is in WW but then again WW are what I mostly use. Oregon outlawed lead in WW so finding them around here is a lost cause. But I've got a life time supply of ingot's on the place!

  20. #80
    Boolit Master
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    Quote Originally Posted by amosfella View Post
    The process is done by slowly and in a very thin stream, pouring the molten metal into a pail filled with ice cubes. HCl will dissolve the zinc, but it will make a very big mess of the lead forming lead choloride. That's a big mess to undo.
    Pouring melted lead on water? It doesn't explode?

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