Gold Elution From Activated Carbon At Room Temperature!!

[Willy bikaka]

Hi brethren!.
I have attached a PDF file providing information on how to elute gold from AC at room temperature using Na2s as eluant that,as according to it,can be completed at about 4 hours!!
Basically this process seems to be a dream come true to me than conventional Zadra or Carbon ashing as I find them more costive especially at artisan scale.
The more challenging part I find when reading the document is understanding the following:
1.It says "Sodium SULPHIDE solution" can "Strip gold from the carbon" ,but I don't understand the next part,does the stripped gold solubilize to gold sulphide ?(..I'm not sure of this Compound being existent or soluble!!!)...or sodium cyanide is needed in conjunction?
2)How is the gold won to solid state?!.Does the sodium SULPHIDE act as both eluant and dissolver?..if "Gold SULPHIDE" is formed ,How is gold separated from the solution__precipitation or electrowinning?!

I've edited the title so it's not in all caps. No need to shout here - FrugalRefiner

 

[Deano]

When sodium sulphide solution is used to strip gold from carbon it forms gold sulfide which is very weakly adsorbed on carbon.
The gold may be recovered by electrowinning from the strip solution but the sulfide ions are degraded during this process.
A similar effect occurs when thiourea is used to strip gold from carbon.
Apart from the strong odour and toxicity of the hydrogen sulfide generated with water contact of the sodium sulfide, the sodium sulfide will form insoluble sulfides with many base metals, most importantly with copper.
Pretty much all metallurgical uses of cyanide involve copper in ores or e-waste, this copper will form insoluble complexes which will occupy loading sites on the carbon as well as blinding gold already loaded on the carbon.
Other base metals have a similar effect but copper is the pervasive one.
If the gold industry is not using a particular method there is always a really good reason for this.
It may be cost, efficiency, toxicity or other reason but it should automatically put up a red flag to someone looking for a magic bullet in their processing.
Deano