Leaching With Chlorine

[CharlieBitMe]

I have searched extensively for online references on halide leaching -- specifically Chlorine. The little information out there talks about iodine and doesn't provide enough detail. There's plenty of information on aqua regia, mercury and cyanide extraction, but I want to learn the specifics of the chlorine process as I think it uses chemicals that are relatively safe and easy to obtain.

My numerous sluicing trips have produced about a bucket of black sand concentrates, which contain micron (mosquito eye) sized gold. The black sand also has some flakes which are heavy and appear to have a blue (almost sky) color and a number of pinky nail sized black opaque crystals which have a reddish/purplish color. This color becomes more black when the crystal is taken out of water.

I would like to leach out the gold from my concentrates. If you have experience with leaching black sands using chlorine, can you please respond in this thread with instructions or shoot me a message if you prefer to correspond directly.

Cheers.

 

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[aussco999]

Hey Charlie:

Just to clarify, aqua regia is a chlorine leach. Here's the simplified explanation; The idea is to convert the metallic gold to a higher valance (II) with chlorine and some form of oxidizer. The oxidizer converts molecular chlorine to nascent chlorine, which attacks the metallic gold and puts it into solution. The draw back with all chlorine leaches is that several base metals will also be converted to their chloride state before the gold goes into solution. This problem is not so true with the other halides, like iodine, but there is a huge cost difference between buying chlorine and iodine. You might want to head over to the GoldRefining.com forum and do a lot of reading on the various chlorine leaches they use to recover refined (jewelry, computers, etc) gold. One of the smarter guys over there (LazerSteve), even sells a How You Do-DIY CD on different chlorine leaches.

Hope this helps and good luck on your project,

John

 

[Sam Burgin]

Interesting thread thus far, so I hope to stay on target. In general, for small quantities of material, the best way to recover all the heavies is to pan them. For any size or fraction of material, if the gold is the heaviest thing in the pan, it will pan out easily.

The problem with leaching is the set-up involved. It's easy to get gold into solution, the problem comes in getting it out. It takes practice.

If you really want to learn about the chemistry of extractive metallurgy, buy the CW Ammen book Recovery and Refining of Precious Metals; THE authorative source on the subject. I got mine at Cotton Patch Gold Mine.

http://www.cottonpatchgoldmine.com/.

Good luck,

Sam

 

[Bunk]

Check this out, I just posted this site on my site this AM. Keep in mind, This man lost his life through a careless mistake! Hey Skip, Help me out here!
Bunk
http://webpages.charter.net/kwilliams00/bcftp/bcftp.htm

 

[CharlieBitMe]

Thanks for the replies guys.

John, the problem with AR is that it's a mixture of HCl and HNO3 and as a binary acid it dissolves not just gold. So there's no specificity in this reaction unless you've done a lot of preliminary work to take out the silver, iron etc. from your solution so you know you're leaching just gold. For this reason AR is not a good pathway to follow. A halide (bleach or iodine) leach will dissolve nothing but platinum and gold regardless of what else is in my concentrates. I tried the goldrefining forum, but the only detailed reply provided instructions on how to leach with Hg (not my cup of tea), not to mention that ideally I want to create a record of the proper procedure here on this forum.

Bunk, that's the web page that gives you a good high level summary of how the process is supposed to work. However even though it talks about a chlorine process, it doesn't provide detailed step by step instructions.

Sam, I'll definitely check out the book you recommend. Hopefully it will have idiot-proof instructions as that is my level of knowledge on the subject .

 

[Hoser John]

Ken slipped and fell on the steps to his own patio,hit his head and died in CR one cool morning--what careless mistake ya refering to??John

 

[aussco999]

Charlie:

I'm well versed in using AR and several of it's different formulas for specific dissolution, but it's still a chlorine leach as per your original post request. And, as I stated before, none of the chlorine leaches will be precious metal specific, but they are the cheapest, easiest and safest leaches available.

And, on a safety note, even a H.S. Chemistry 101 class teaches that no chemical or a combination of chemicals capable of leaching metals should be considered to be "relatively safe", without some proper training.

With access to the internet and all of the people that have done this before, there is an abundance of available info to extract a little bit of gold from a bucket of black sands. You just need to choose a system that works best for you. I didn't read that part were someone recommend using mercury as a leach, which is impossible, as much as they were probably recommending using mercury as a collector for your fine gold.

Iodine is a somewhat more specific leach, but has never caught on commercially, because of the high costs involved, especially when cheaper leaches are available. There is a lot of info on-line for using iodine as a leach (see Google), and even several downloadable U.S. Patents for your reading enjoyment. But, most of this material assumes that you have some chemical background and understand the basic fundamentals of the process.

The only other leaches (that I'm aware of) that are more precious metal specific (sort of), are cyanide, thiourea and the Haber process. Cyanide is probably the best leach and has a very good safety record, in trained hands, but when things go bad, it goes real bad. Thiourea was making a strong comeback as a specific leach until they found out that it often converts to a carcinogenic compound. And, the Haber process,,, well,,, only those people know about that process and are unwilling to share that info with anyone for a bucket of black sands.

You might want to look at a different way to extract the micron gold from your black sands (i.e. acid pre-wash, pulverizing, magnetic separation, flotation), and then a simple chlorine leach. All of the base metal chloride problems have proven, simple solutions and you will be left with high grade gold.

And, a heads up on the both of C. W. Ammen’s books. They are great “How to/DIY” books and I own both. But, there is no discussion in either book on iodine leaching as he doesn't consider that a viable leach either. He does go into great step-by-step detail on using chlorine leaches, and both editions of his books have a chapter dedicated to the treatment of black sands.

Let us know how your project progress, and good luck,

John

 

[Bunk]

Ken slipped and fell on the steps to his own patio,hit his head and died in CR one cool morning--what careless mistake ya refering to??John

John, After I posted his site, I was told thats how he passed away. Sorry for the mixup.
Still, anyone new to the gold game should not mess with the chemical side of things, just save your black sands until you have a barrel of non magnetic. Them you might have enough to make it worth your while, then get help.
Bunk

 

[homefires]

Here you go!

http://webpages.charter.net/kwilliams00/bcftp/bcftp.htm

OOps! Someone aready posted that one!

 

[Ragnor]

The charter website is no longer responding. Did anyone ever save Kens work into a PDF?