Handbook of Commercial Bullet Casting from Star/Magma discusses this and other procedures. I don't have my copy handy so I can't give more details. Lye is usually available in grocery and hardware stores. Be careful with it.
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Handbook of Commercial Bullet Casting from Star/Magma discusses this and other procedures. I don't have my copy handy so I can't give more details. Lye is usually available in grocery and hardware stores. Be careful with it.
Some dummy where I worked, disposed of some sodium hydroxide in the dumpster and the trash truck made it across the street to the next pickup before starting to smolder. When they activated the compactor it caused the powder to be expelled and landed on half a doz cars. The results involved two fire trucks and a hazmat team. That stupid mistake cost several grand and a fine from OSHA.
As with all chemicals, there are procedures to follow and safe ways to use them. Ignorance and serious chemicals don't mix well.
Information not shared. is wasted.
Roasting is done on sulfide ores (including galena, lead sulfide) to convert them to oxides. The oxides are either reduced to metals by heating with carbon, or dissolved in acids and reduced to metals by electrolysis, plating them out.
Looking across the Periodic Table from left to right (and ignoring Hydrogen, which is kind of unique), we find that water soluble compounds of the elements on the left tend to be strong alkalis (bases), while those of the elements on the right are strong acids. Alternatively, we can note that the elements in the column on the left tend to be strongly metallic, while those in the right-hand column are strongly non-metallic. As we go from left to right, the metallic characteristics get weaker and the nonmetallic characteristics get more pronounced.
The elements in the middle can act as metals or non-metals, depending upon what they are reacting with. Lead or zinc are in the middle, so they can react as metals do with a strong nonmetal acid like hydrochloric acid, reacting to form lead or zinc chloride. Lead is much less reactive than zinc, but they both react in this manner. The chlorides will dissolve to a greater or lesser extent in the water that carries the acid.
Lead and zinc can also act like nonmetals, reacting with a strong metallic alkali like sodium hydroxide the way a nonmetallic acidic element like chlorine would, forming a plumbate or zincate. Again, lead is much less reactive than zinc, so if you had a mixture of lead and zinc, the zinc would react first. The plumbate or zincate would dissolve, depending on their solubilities, in the molten sodium hydroxide or in its water solution.
Speaking as one who has had a more than sufficient number of chemical burns in my career, I would say that alkalis do much more and much more painful damage to the skin than most acids, given the same exposure and time before washing off. Sodium hydroxide is also deliquescent, which means that out in humid air, it will absorb enough moisture to liquefy. On the old beam balances, it took a good technician to weigh the stuff out quickly enough so the atmospheric moisture didn't add to the weight. Tossing some of this moisturized alkali into a pot of molten lead and stirring it good would be mapping yourself out for an ambulance ride if you aren't careful. "Careful" meaning all the personal protective equipment MaryB mentioned in her post.
On the other hand, chemically speaking, the reaction should work to the extent that all the zinc should react before much of the lead does, and the dissolved zincate should float in the layer of molten sodium hydroxide on top of the molten lead.This reaction will generate heat, which may or may not further endanger the operator. It will also react in mostly uncharacterized ways with the grease, oils, tar and whatever else the lead is contaminated with. This may add to the hazards as well.
So if you have enough contaminated lead, or are desperate enough to need to do this, I would suggest shields, gloves, goggles, rubber suits, remote stirring and heat controls, and anything else that isolates you from the effects of splattering. The lead and alkali should be brought up to temperature slowly, just as if there was a suspicion of water in the lead. If you think a burn from a flying droplet of molten lead is bad, it's nothing compared to a similar drop of molten sodium hydroxide. That's a burn that keeps on burning.
One of my college chem profs said that the reason alkali burns are so bad is that they convert your skin/body oils/fats into soap which then washes away leaving fresh tissue for it to work on. I would take my chances with molar strength acid before a molar strength base, although my first choice is none of the above.
No you are correct. it's not an acid, it's a strong base. very very strong base.Originally Posted by William Yanda
OK.
I see the safety nazis are out in full force. Great.
As much as I do appreciate your input and concern, go back and review my original post. I am (or was) looking for an intelligent conversation concerning the chemistry and metallurgy involved with this process for purifying lead.
We ARE dealing with a chemical that has known hazards. One of those hazards, is that it will eat the meat off your bones.
You have a personal choice on how to handle this chemical. You can handle it in a safe manner and not be harmed by it, or can can handle it in a unsafe manner and suffer some personal injury from it. Bottom line is, that is up to you.
If you hurt yourself with this chemical, that is not the chemicals fault, nor is it my fault for discussing the use of this chemical.
Do your own research, know the risks, and use your own personal safety gear as to how you see fit to protect yourself.
I expect the discussion and the knowledge shared about this to be about the purification of lead.
I don't expect this to be a safety lecture from my mother.
Having said that, I had to try this today (in spite of you guys) and I can say that it has some very interesting and promising results.
Hutch,
This is a very good and valid question.
I agree with the initial concept that if tin, antimony and arsenic are the 'good' metals, why would we want to remove them?
First off, this is more that just the 'because I can' argument.
I've seen more than a couple of forum questions where guys ask if they can remove the antimony and soften lead. Generally, the answer had been 'no you can't' or ' yes you can, but it's is beyond your skill and ability'; no real answers and nothing beyond that.
Two people that come to mind that want softer purer lead are the muzzle loader guys, and the swaging guys. I'm looking at this from the swaging aspect, as well as from the simple curiosity aspect of the process.
The second reason for my curiosity in this: I have been fortunate enough to be able to mix my own alloys from virgin clean metals using raw stock. I can tell you, and probably many other as well, that a clean, say 6/2/92 alloy will cast WAY better than the 'scrap' that most of us are use to. This includes wheel weight, Iso core lead, roofing or x-ray sheet lead, etc. All the stuff the we tend to scrounge for free and nearly so.
I am pretty sure that there there are two types of lead out there. First is the pyrometallurical lead, that is the lead from the blast furnace, and then there is the electrochemical lead that has gone through the electrolysis refining at a much higher cost and purity. I'm pretty sure most of the wheel weight alloy is made straight from the furnaces and carries a lot of impurities with it, and is good enough for the purpose it serves. Same with ISO lead, same with the sheet leads.
If we can purify a relatively cheap lead source to use, in a cost effective manner, and then alloy it with known additives... I'm sure that would interest a lot of people. At the very least, it's worth discussing, and maybe some experimentation.
I see many people who build PID's so they can cast at the 'perfect' temperature as well as guys that take details to the nth degree. All in search of perfection.
One of the questions that seems to have not been answered yet is "where can I get pure lead that I don't have to pay a fortune for?"
There may be an answer for that.
Hey Trigger,
So far, you seem to be the only person that shares a curiosity in this.
PM me an email addr and I'll send you the info I'm working off of.
To answer your question, from what I've done today, I think I can say the following:
Can you purify lead and pull the additives out? - Yes
Can you do this at home on a small scale? - Yes
Can you do it with readily available hardware store stuff. - Probably, yes.
Can you do this without harming yourself? - uhmm, according to everyone else here, probably not. Pretty sure you're gonna die. This process was known as a 'softening process' for lead way back in the 1800's and I'm pretty sure everyone who was doing it back then is now dead.... so maybe we shouldn't answer that question just yet. That outlook, based on statistics doesn't look favorable.
I am also interested in this process, although only as an academic exercise. Having come into accidental contact with strong acids and knowing their relation to strong bases, I can see why there is so much concern for safety.
I wonder for the home user if an aquaeous reaction might be safer: zinc and other metallic impurities are typically far more reactive with both aquaeous HCl and aquaeous NaOH than lead, so perhaps a wash with high surface area (cooling bin for a shot dripper comes to mind) would remove a significant portion of the impurities without the dangers of working with molten NaOH.
Just to answer this question up front, no I don't think an aquaious use of Na OH is better.
Just to put this in perspective, I run a 'hot tank' with caustic soda and sodium nitrate. The nitrate is used for corrosion protection. That's why I have these chemicals on hand.
After about 180 degrees, a hot tank will tend to boil off caustic fumes, and yes those are nasty. That's why 'hot tanks' tend to run at 180 rather than 210, where they would be more effective.
I will say, that 'fused' NaOH (molten) seems to give off little to no fume. I was surprised at that, even tho prepared for the worst.
For those that have done the sulpher burn to remove zinc, this is WAY less hazardous as far as off gassing. The SO2 is pretty nasty and REQUIRES a chemical respirator. Molten NaOH is pretty tame and I'm sure could be done without a respirator. Aqueous NaOH - Different story, you want some protection.
Last edited by B.C.Jay; 08-28-2017 at 10:37 PM.
I was not suggesting that the aquaeous reaction should happen near boiling; rather, that increasing the surface area of the reaction will help overcome the limitations of a solid/liquid reaction, and that the cooling tray of a shot dripper might be the ideal place for such a reaction to take place. Anything that creates noxious fumes is basically unsafe for home use because generally people are not consistent about how they treat this sort of hazard.
I agree, most people don't take the hazards seriously.
I was actually surprised at how little fume was produced by the molten caustic vs the hydrous caustic, as I'm quite familiar with the hydrous fume.
As compared to the 'zinc removal with sulphur', quite honestly, this is quite safe and a walk in the park in comparison.
As this is a 800 degree process and chemical reaction, water in any form is definitely not part of the equation.
[QUOTE=B.C.Jay;4138258]Hey Trigger,
So far, you seem to be the only person that shares a curiosity in this.
To answer your question, from what I've done today, I think I can say the following:
Can you purify lead and pull the additives out? - Yes unquote!
ok To clarify, I am the type of guy that tries to maintain a positive out look on all things. I always ask "IS IT POSSIBLE"? Yes, I am curious by nature. Always have been. When I first joined here, removal of antimony was one of my first questions i had............. Because I am a muzzle loader shooter. I read all I could find............ and found That I could just sell or trade for the pure I needed. But curiosity, keeps tugging at me, what if-what if. if there were a simple and cheap/safe way............. I am all ears. I am sitting on 4000 pounds of range scrap that is 100 % Zinc free. But bucket to bucket analysis differs, because of the introduction of lead shot. The antimony % is different from bucket to bucket. So I have to melt and test every bucket before I can offer it for sale( most everyone wants to know the composition). This adds to the cost of production for each batch Which chops away at any possibility to make extra beer money.
I just came home and emptied the casting pot which had 'roofing lead' in it. Typical platinum silver color, kinda dirty, has some crud in it.
Replaced it with the lead I 'purified' today - very silvery sheen to it and hardens with a dark navy/ purplish sheen to it. Pure lead.
Going to cast some cores with it.
So: how do we get there?
Hey Trigger.
From what I gather, removing copper is done in two stages. The first stage is to cool the alloy and skim off the 'oatmeal'.
I played with adding babbitt to alloy for the tin content and it got weird and oatmealy, i'm sure that was because of the copper.
To remove, cool the alloy to almost freezing and skim off any of the dross that goes partially hard.
That gets rid of most of the true 'heavy' metals. Copper will remain in solution to about 0.5%.
To remove the rest of the copper, treat with sulphur as per the removing zinc with sulphur instructions.
Last edited by B.C.Jay; 08-28-2017 at 10:41 PM.
To remove antimony, tin and arsenic, follow along:
How to purify lead using the 'Harris process'
The Harris process is used to purify lead, both before and after the 'Bess process' which is the electrolysis of lead. Some metals are only recovered during electrolysis which include bismuth, gold, cadmium and a few others.
Most of the metals that have an affinity to lead, tin, antimony, arsenic and tellarium, carry though.
The 'Harris Process' uses caustic soda and sodium nitrate to oxidize and capture these metals that have an affinity for lead.
The amount of sodium nitrate is calculated based on the amount of metals you want to remove. The sodium hydroxide is used until saturated, then removed and replaced with fresh sodium hydroxide.
The process is repeated until the lead is pure.
Todays results:
I took about 10 lbs of 'roofing lead' which obviously had some tin and or antimony content and melted it down with 1/4 cup NaOH and about a teaspoon of sodium nitrate.
Due to NaOH being hydroscopic, I put it in first, along with about a teaspoon of sodium nitrate. As it melts, it boils off any water that's present. Add the lead, and it melts in to the pot.
Once everything is melted, the slurry on top boils quite a bit and is foamy.
At that point, everything is stirred together as vigorously as possible, without splashing anything outside of the pot.
After about 20 Min, the foam ceases, and the slurry on top becomes about the consistancy of pancake batter and a battleship grey color.
The color is due to the tin and antimonial salts being suspended in the caustic.
Once all the tin/antimony is is removed, the metal with continue to heat until the lead starts to oxidize with the familiar purple hue. Stirring the mixture at that point will put a yellow/gold swirl into the slurry and at that point you know you are done. The yellow/gold will mix into the NaOH flux similar to caramel in ice cream. At that point, you are removing lead oxides as all of the tin/antimony/arsenic is gone.
Pour the lead off and deal with the flux as per next msg.
Last edited by B.C.Jay; 08-28-2017 at 10:06 PM.
If the the NaOH slurry, becomes dry and crystalized, it is saturated and should be skimmed off and the process should be repeated with fresh caustic and salt.
That didn't happen to me as I was using 'near' pure lead, so it cleaned up before that.
What I got was lead that acted as 'pure' lead. It oxidized with the purple hue. It poured and cast into ingot and stayed very shiney until hard.
Once I remelted it in my pot, it left a very blue/purple hue.
The untreated metal I poured out had a platinum sheen that was not mirror shiney.
These two metals are NOT the same, despite being from the same source.
Bottom line: Does this work? YES.
Oh and if someone tries this, don't throw away the NaOH slag, there's a really easy way to deal with it and recover the caustic.
Boil the pot with water and it will come out cleaner that your have ever seen it. But don't throw that solution away yet either. Throw it in a bucket for now.
Bonus points to someone who can tell me how to handle to NaOH and metal salt solution in the bucket....
Hey Bent R,
I have to respond to this just for historical reasons.
I used to work for Teck, Trail back in the 90's. At that time they were still running the roaster plant, doing exactly what your describe. Burning off all the sulphides before the blast furnace.
From what I gather, the new process eliminates the roasters and does all that in the furnaces.
I can't remember exactly what when on, but I remember that they tried the QSL furnace on a larger scale and it didn't work, so they scrapped that to go back to the Kivcet process. Either option eliminated the sulphide roasters. I never did get to see any of the plant or the original furnaces before they were decommissioned. Wish I did.
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