Recovery of gold and disposal of stripper

A. A good amount of organics in the gold stripper can be easily adsorbed onto

1) Activated carbon and then dispose off in a well equipped incinerator.

2) Certain ion exchange resins can also remove these organics

But the first is simpler.

There are CN destruction techniques in which organics are also destroyed significantly.

A. In Gold stripping solution, there are 3 substances as following:

1. cyanide

2. organic(nitrobenzene sulfonate)

3. metallic ion ( Pb ,Zn).

If you removed gold by electrowinning, metallic ion and some part of cyanide would deposited on cathode and being oxidized respectively. The remained cyanide can be get rid off by oxidizing agent for instance hydrogen peroxide or hypochlorite. The last substance is organic part that is difficult to remove even using activated carbon.

A. I would plate the gold out onto a mild steel cathode, using a graphite or platinium clad titanium anode.

When I had recovered all the Au, I'd either add sodium chloride and continue electrolyzing, or do alkaline chlorination for cyanide destruction. The gold could be easily removed from the cathode by immersing in hydrochloric acid. It will eat away beneath the non adherent Au deposit and the gold will fall to the bottom, as easily smelted flakes.

A. You may kill the gold stripper solution by addition of sodium thiosulphate ⇦ this on eBay or Amazon [affil links] . After addition of sodium thiosulphate, add potassium hydroxide and zinc.
you will get gold without any danger.

A. Hi, Prashant.

There is usually more than one way to do something and this is no exception :-)

The gold may be removed by ion exchange, in which case it is usual to burn the resin for recovery (although there's more than one way there too); or the gold may be plated out in a plating cell specially designed with close anode to cathode spacing, large electrode area, and solution agitation. Custom equipment for this is available from companies like PMPC who offer their "Goldbug®".

After the gold has been recovered, the cyanide is destroyed, usually by alkaline chlorination. Although it is possible to learn all of this from reading a couple of books, it really is best to get some hands-on instruction. Good luck.

Regards,

A. Hi Prashant,
First you add same quantity of water in stripping solution then add NaOH depending on your alloyed (kt) gold loss in it. than you add zinc in it, stay it for one whole night to complete reaction. you will get cement type residue after filtration; wash it, dry it to 500° c in furnace and treat it with nitric acid to get Ag then again filter wash and dry residue of contaminated gold in furnace to 650° c treat it with aqua regia. disposal of cyanide - I think you read MSDS of cyanide in internet or you can use na hypochlorite but it is dangerous (Dis. in H2O conc. NOT to exceed 25 mg/mL. Mix with 1 vol. of a 1M sodium hydroxide sol. and 2 vols. of a FRESH 5.25% sodium hypochlorite solution [have someone else] stir for 3 hours. Test for completeness of destruction, neutralize and discard.)