# precipitate gold out of gold strike solution w/ cyanide



## eleazar (Aug 20, 2013)

......hi guys....i'm a goldsmith in philippines but...eventually residing here in taiwan...i am dealing w/jewelries.... i make 24k gold strike solution w/ cyanide...my question was...can HCL destroy or neutralize the cyanide in the solution...?if yes....it is possible to use SMB to precipitate gold...?the elements that i used were as follows 1gm 24kgold... 1L distilled water..little amount of muriatic and nitric acid and aprroximately 4-5gms of sodium cyanide....all i want to know is how could possibly regain or recover gold back from its original property.....could you help me guys..... on this matter..thanksa lot...!!!


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## g_axelsson (Aug 20, 2013)

I'm sure someone will help you with the details on how to recover your gold.
But in the mean time, do NOT mix acid and cyanide!
It will create deadly hydrogen cyanide gas and can kill you!
http://en.wikipedia.org/wiki/Hydrogen_cyanide
"A hydrogen cyanide concentration of 300 mg/m3 in air will kill a human within 10–60 minutes."

Göran


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## Harold_V (Aug 20, 2013)

Use zinc flour (dust) to recover the values. If you expect to recover an ounce, use an ounce of zinc. A little extra does no harm, and is easy to remove once the gold has been cemented. 

As has been suggested, DO NOT MIX CYANIDE AND ACID. The result is a deadly gas. 

Harold


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## eleazar (Aug 20, 2013)

..thank you guys....i have just read it from hokes book..dropping 5 times drops of HCL on gold cyanide solution...because stannous solution could not detect gold with alkaline neither cyanide solution.....could you help me guys in dealing with zinc cementation process i don't know the step by step procedure....is theres a current on it that should be used?please help me guys....by the way thank you very much for your cautious advice...it makes sense to me now that cyanide-HCL is a No-No in recovering gold....cause it will harm everybody around me as well as mother nature...thanks to the forum...educating people and helping to widen and increasing more knowkedge.....thanks a lot and more power to all.......!!!!


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## Harold_V (Aug 21, 2013)

You need almost no help in recovering the gold. Do not complicate the process by over thinking. 

It is helpful if there is a trace of free cyanide in the solution, so if you have some at your disposal, introduce a few bits, then stir until they are dissolved. Weigh out the prescribed amount of zinc, stir the solution very well, and introduce the zinc as you keep stirring. Done. 

If the gold content is high, you will see an instant conversion. The dull gray zinc will transform to a brown substance (gold). If there is very little gold present, you may not see anything happen at all. 

If there is an over abundance of cyanide present, you risk having the cemented gold get re-dissolved. For that reason, I had a tendency to introduce a little more zinc after the initial precipitation, to ensure that any that did get dissolved was recovered. 

Allow the cemented gold to settle well, then siphon off the cyanide solution. Rinse the solids well (tap water is acceptable), then WORKING IN A FUME HOOD, dissolve the remaining zinc with HCl. The resulting gold may be of high quality, but you can ensure it is good by refining the material. Adding HCl to this material without the use of a hood is risky business, even if you have rinsed the recovered values well. 

Harold


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## Gratilla (Aug 21, 2013)

I have heard that some cyanide users here in Indonesia add hydrochloric (ie muriatic) acid to their mix. I have absolutely no clue as to why. In fact it sounds a bit dumb.

The chemical formula for the reaction I would suspect would be something like:

HCl + NaCN -> NaCl + HCN

with HCN (hydrogen cyanide) being a toxic gas, as previously mentioned.



eleazar said:


> ...i have just read it from hokes book..dropping 5 times drops of HCL on gold cyanide solution...



Did Hoke really say this? I must've missed it. IMO cyanide solutions should always be kept strongly alkali to be safe.


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## Harold_V (Aug 21, 2013)

Gratilla said:


> I have heard that some cyanide users here in Indonesia add hydrochloric (ie muriatic) acid to their mix. I have absolutely no clue as to why. In fact it sounds a bit dumb.
> 
> The chemical formula for the reaction I would suspect would be something like:
> 
> ...


It has been MANY years since I looked at Hoke's book---but if she did make that recommendation, I would suspect it is to allow for testing with stannous chloride. The very small sample (a single drop) would most likely not liberate enough gas to be of concern. If that isn't the case, I have no idea why one would want to introduce HCl to cyanide. 

Comments?

Harold


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## eleazar (Aug 21, 2013)

........im so sorry for not detailing on you guys on what i have read....on hoke book....it made you misleaded you anyway.......sorry for what i have quoted.....its my fault not digesting all what is written on the book......in chapter 9..... page 91......
hoke says;
thus.suppose you have an old CYANIDE gilding solution take about five 
drops of the suspected liquid in a small test tube or tiny beaker,stand near
window or exhaust fan,and ADD FOUR OR FIVE DROPS OF HYDROCHLO- 
RIC ACID.the fumes evolved are EXTREMELY POISONOUS,hence the need
of working near an exhaust.bring the mixture cautiously to a boil,this 
drives off CYANIDE.let it cool,and now you can TEST with copperas as
usual......
.....now it makes sense to me now that he did it only for testing..but not on recovering the entire cyanide solution.......so sorry guys.....


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## Gratilla (Aug 21, 2013)

Ahh, that's more like it. And thanks for the clarification with all the important safety caveats capitalized.

On a not-completely-unrelated topic; if I'd read Hoke more recently, then I would've been more sensitive to her reference to "cyanide gilding solution". Just yesterday we received our first sample shipment of gold leaf materials to attempt gilding, ie "dry method", in our furniture business. I have read about a "wet method", ie using cyanide solution and will now put that on my ToDo list for future comparison.


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## laxman (Oct 5, 2013)

Hi all user 

i tried this math ode very small precipitate use SBS 

how large precipitate mud make which chemical better 

http://www.metalminemedia.com/2013/03/gold-recovery-method-aqua-regia.html




Gratilla said:


> Ahh, that's more like it. And thanks for the clarification with all the important safety caveats capitalized.
> 
> On a not-completely-unrelated topic; if I'd read Hoke more recently, then I would've been more sensitive to her reference to "cyanide gilding solution". Just yesterday we received our first sample shipment of gold leaf materials to attempt gilding, ie "dry method", in our furniture business. I have read about a "wet method", ie using cyanide solution and will now put that on my ToDo list for future comparison.


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## g_axelsson (Oct 6, 2013)

laxman said:


> Hi all user
> 
> i tried this math ode very small precipitate use SBS
> 
> ...


Hi Laxman and welcome to the forum,

On the link above is the recipe of a complete mess. It is written by someone that doesn't understand how to refine. Do never drop electronic scrap in aqua regia directly. The instructions start


> Cut the parts of the circuit boards that contain gold and put them in the bucket & throw away the other parts of the board. If you also have CPU chips hit them with a hammer as the gold parts are usually inside the chip. Place these in the bucket too.


Always remove the base metals before dissolving the gold.
The rest is so full of mistakes I'm not going to list them all.

The document you uploaded is also full of mistakes. It starts with


> CPU Pins are made of pure Gold and Silver


Which is totally false. No CPU pins are made from silver. Gold plated, yes, but the base is made from kovar, brass or bronze. The document has no mention of ratios or any safety precautions.

You need to read more until you get a good grip of the process. Read Hoke, do her acquaintance experiments and ask if it is something in it you don't understand. Put weight on learning to test for gold in solution and read about safety and dealing with wastes here on the forum. A lot has happened in that area since Hoke's days.

Good luck!

Göran


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## Lino1406 (Nov 18, 2013)

The next edition of "30 recovery procedures..." will answer this issue as well as many
others


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## Lino1406 (Dec 1, 2013)

To begin with, it is of major importance if you
have FREE cyanide in the system - that is more
CN- than just included in KAu(CN)2-4


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## Lino1406 (Dec 11, 2013)

After a series of experiments - the best reducer
for gold cyanide is found to be
sodium dithionite (hydrosulphite),
a chemical from the textile industry.
Preferably in the powder form.
According with free cyanide and the freshness
of dithionite - the surplus needed
(over equivalent amount).


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