Economical Source of Zinc

[TariqMujahid]

Hey. I'm not sure about the cost of Zinc or how difficult it is to obtain, but I've found a solid source of it at a pretty low cost...atleast for those of us in the United States. It's one of those things that make you think "Duh" once you've read it:

Materials:
-Beaker (Any size will do)
-Etchant Solution (9% FeCl3: 91% Water): bought at Radioshack for $4.95 USD
-Pennies made after 1983

NOTE: After buying the FeCl3 solution with the hopes of making Phosphorus Trichloride out of it and realizing it wouldn't work, I was messing around late at night to find some good use for it. Therefore, I didn't make any measurements...sorry friends. Also, I don't know any good uses for Zinc, flash powder maybe? I don't have any use for it, I just thought this information might be helpful =).

Procedure:
-Put the pennies in the beaker, and cover them with the Etchant Solution. I didn't measure how much Etchant Solution I used. I just poured in enough Etchant Solution so I couldn't see through it to the pennies.

-Let the pennies sit in the solution for 1 Hour and 30 minutes - 2 Hours, stirring and moving the pennies around occasionally. Applying heat can speed the chemical reaction up, I'm assuming. I'm making this assumption because on the bottle of Etchant Solution, it says, "Etching may take more or less time, depending on the temperature of the solution."

-After the time is up, remove the pennies from the solution and dispose of the solution down the toilet. The copper coating should be like mud now. Rinse the pennies off in warm water, and rub them dry to remove the copper coating. You should be left with a high quality piece of Zinc, which is a dark bluish color. I imagine you will want to grind this down into a powder to make it more usable.

This seems like something very obvious, but after searching the forum, I found no posts on it. Has anyone else been using this method all along? Or do you have better ways of accomplishing this task?

Sorry about this...after looking through the Forums again, I realized this post would be more appropriate in the "Miscellaneous" section. If someone could be so kind as to move it there...

<small>[ May 05, 2002, 04:21 PM: Message edited by: TariqMujahid ]</small>

[Polverone]

You can also remove the thin copper shell with a mixture of HCl and H2O2. You don't need to use very much of either, and these are 2 chemicals that many Forumites already have on hand. Or, for super-crude pyro devices, you can just mix pennies in with a hot, slow burning composition. The zinc will ignite in bulk with high enough temperatures. You can do the same thing tossing pennies into a charcoal fire, especially if you blow a stream of air onto it. It has very little to do with weapons or explosives, but there's just something wrong with you if you don't enjoy those pretty blue-green flames :)

I believe that zinc dust is produced by vaporizing it under an inert atmosphere and recondensing, but that's probably beyond most people's lab setups. I can't remember if zinc is particularly brittle at low temperatures or not. If so, it could be pulverized after chilling with LN2. It does irk me to pay more than $10.00/lb for zinc dust, but my time is worth something also, so I've never tried to reduce bulk zinc to powder as an amateur.

[VX]

Anyone know if this will work with English pennies?

I always thought that they would just be an alloy.

[Rhadon]

Using pennies shouldn't be that economic... try a large 'clunker seller' (don't know the correct word for it), if he's friendly he'll give it to you for free. I got 500 g without paying for it, that's enough for some experiments :)

[vulture]

Like I mentioned before, open an alkaline battery, there's very fine zinc powder in there. There's some grease on it however, which you will have to extract with toluene or something.

[Zach]

i think you mean "junk dealer", right?
many carbouraters here in the us of a are made of zinc.... as are a smaller number of hand brake levers from motorcycles

[Rhadon]

Yes, "junk dealer" should be the right word for it.

[Arkangel]

I've been considering investing in some marine sacrificial anodes, since they are supposedly pure Zinc. You'd still have the trouble of reducing it to a powder, but at least you can dispense with the ballache of removing coating metals.

They are pretty cheap, available from any chandlery shop and come in all sizes up to a few kilos. The ones I REALLY want to get are made from Magnesium, but haven't had time to look properly yet.

[Polverone]

This weekend I tried to prepare some zinc powder starting from the crudest and most available of materials. To make a longish story short, this is probably worth trying if you can't/won't buy zinc dust from a chemical supplier. It is only economical if your time has no value. Anyway, on with the show!

PREPARATION OF ZINC CHLORIDE SOLUTION

I went home for Mother's Day so I had an extremely limited selection of chemicals and equipment available this weekend. I started from post-1981 U.S. pennies as my crude zinc source. They were the only zinc I had around. There is a thin copper shell around the core of each penny which I had to pierce so that the zinc could react with hydrochloric acid. The piercing can be done mechanically, using an awl, nail, or pair of wire cutters to put a scratch or gap in the shell. A faster and more effective method is to destroy the shell in many places with a mixture of HCl and H2O2. I placed about 20 pennies in the bottom of an empty plastic coke bottle and added about 100 ml of an equal volume mixture of paint-grade HCl and 3% H2O2.

The liquid will turn green as copper is dissolved. When the pennies' shells start failing, there will be bubbling that will increase considerably in vigor as more zinc is exposed. As the zinc starts reacting the color of the liquid will disappear, since the more electropositive zinc will plate out the copper that has dissolved and the iron contamination that gives paint store HCl its lovely yellow hue. Once the shells were well-pierced I added additional acid and sat back for a bit. The reaction becomes very vigorous. The container eventually became too hot to hold and started shrinking/deforming because of the temperature. Considerable HCl was driven off by the heat as well. Don't do this indoors unless you can moderate the reaction.

REACTION WITH ALUMINUM FOIL

As the reaction slowed down and tapered off, I transferred the mix of metals and liquid into a glass jar and heated it in a water bath on the stove. I wanted to make sure that most of the HCl had been consumed. I made sure that there was always an excess of zinc available. After an hour or so of heating I decided it was time to try recovering the zinc. I filtered out some of the liquid into a pyrex custard cup and added squares of aluminum foil. No reaction. I thought maybe it needed a better kick to get going, so I heated the custard cup on the stove. Eventually, at about the same time the liquid began boiling, the foil began reacting. Once it got started things seemed to go much easier. Considerable hydrogen is evolved at this stage, which is rather amusing when using a gas stove. Once the foil reaction gets going it can actually be annoyingly vigorous, splattering the suroundings with liquid and foil bits. After some foil had been consumed it seemed that subsequent pieces of foil started much more easily. This could have just been due to the further concentration of the liquid achieved by frequent heating. The liquid turned dark gray and then black. I assume that this was from extremely fine zinc. Sadly, this material was not very persistent, being easily consumed by the remaining acid in the mixture, at which point the liquid was again clear.

The aluminum foil seemed to turn gray and then stop bubbling. When I plucked some out, I discovered that it had been converted to a porous zinc foil. This foil was easily ignited with a match when dry. As I packed more sheets of foil into the limited confines of the cup, lower layers of crumbly zinc foil compacted into clumps that could not be easily separated. When I had grown tired of preparing zinc foil I dumped the whole mess into cold water and rinsed it. While the foil clumps were sitting on a paper towel I could hear them fizzing still, presumably from excess acid, so I dumped them into water again, added some baking soda, and swirled vigorously until bubbling ceased. Then I pressed the metal dry between paper towels and stuck it back in the (now clean) custard dish to dry it on the stove.

After some time of heating over the stove I decided that my zinc was sufficiently dry. The biggest clue was that one of the clumps in the dish ignited. Fortunately, it did not touch off the rest. I let the zinc cool and then tried to crumble it up more. I was able to obtain a decent powder by crushing and rubbing the dry foil lumps between two spoons. No doubt this task would better be accomplished by a ball mill. I hope to prepare some more foil and introduce it to a mill in the future. Some of the powder was quite fine. It could probably be separated by sifting through a t-shirt or similar.

When I made a second attempt to prepare zinc dust/foil on the following day, the liquid that I used had been in contact with the zinc for nearly 20 hours longer, and was correspondingly less acidic. It was very difficult to start the reaction this time. Several minutes of contact with boiling liquid were required to initiate the reaction of the aluminum foil. Again, once it started it was easier to make subsequent pieces of foil react.

EXAMINATION OF PRODUCT

When mixed with sulfur and/or potassium nitrate, the crude zinc dust/foil fragments made a respectable pyrotechnic mixture. It would no doubt have been better had I screened out the larger chunks.

FUTURE WORK

Although it was a very tedious process to prepare zinc from its chloride this time, I may be able to do it much more easily now that I have access to my lab equipment again. In the future I am going to try preparing larger batches of zinc chloride solution, and also reacting the foil with it in a larger vessel. I am not going to make any special effort to consume *all* of the HCl with zinc since it seems that a somewhat acidic solution is needed to break the initial oxide layer on the aluminum foil. If I were able to use a vessel large enough that it can contain a fair amount of bubbling without splattering all about, the preparation would be much less tedious. I am also interested in processing the foil in my improvised ball mill, though I may need to get some marbles first. Since the zinc foil's tendency is to disintegrate already, I suspect it will be much easier to mill than aluminum foil.