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"Recovery of gold and disposal of stripper"

An ongoing discussion beginning back in 1998 ...


Q. Dear Sir,

Can anyone suggest an effective method to treat cyanide gold stripper? We remove the gold by electrolytic machine and destroy the cyanide using sodium hypochlorite. We found that the COD content in the stripper solution is 20,000 ppm.

Our local regulation parameter limits for COD is 100 ppm before discharging.

Looking forward to a favorable comment.Thank You



Q. We are having some problem on discharging the gold stripper after reclaimed the gold. It contains a lot of cyanide and complexing agent. The concentration of COD in the solution is more than 20,000 ppm. Therefore, we couldn't dump the solution after the cyanide destruction.

Any further help or experience would be appreciated.

Teoh Meng Soon


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.

- Bangalore, INDIA


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.

Pramot Pupanthong
- Bangkok, Thailand


Q. Hi Everyone
I am working in E-waste Recycling company. We are recovering metals from E-waste.
In one of our process we use cyanide solution to strip off the gold from waste materials, for this I need to use a Gold stripper to remove gold alone leaving other metals like copper, nickel etc in the material itself.
Can anyone guide me on the composition of a gold stripper.

Dinesh Rajamanickam
- Penang, Malaysia

De-activating gold stripper solution


Q. I presently, use a cyanide based gold sripper solution. After sometime the gold stripper is still active. I need to recover the gold from the stripper through a gold recovery system. Advise given was as follows:-
1) Strip more gold parts until the gold stripper is no longer active.
2) If I need a quick fix it was suggested I add Sodium Hydroxide and Formalin into the gold stripper.

Any advise as to what the proportions of NaOH and formalin would be. I understand that formalin is a toxic substance. Or any other ways which I can 'kill' the gold stripper.

Poobalan Loganathan
Electroplater - Singapore


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.

dave wichern
Dave Wichern
Consultant - The Bronx, New York

October 15, 2008

A. You may kill the gold stripper solution by addition of sodium thiosulphate [affil. link to info/product on Amazon]. After addition of sodium thiosulphate, add potassium hydroxide and zinc.
you will get gold without any danger.

- Coimbatore, Tamil Nadu, India

February 28, 2011

Q. Hello,

I am really interested about the content of gold stripper. It is same for all gold stripper or it depends on the chemicals we used in the extracting gold from e-waste?

Fida Yahaya
university - Malaysia

Recovering gold from cyanide stripping solution and neutralizing cyanide before disposal?

May 3, 2011

I want to know how to recover gold from cyanide solution and how to neutralize it before throwing it in sewage?


May 2011

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.


Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

May 8, 2011

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.)

Bhupesh Mulik
- Mumbai, India

October 11, 2019

Q. Hi, I have leftover stripping solution from a potassium cyanide gold and I would like to know if it's possible to substitute the zinc 235 mesh with sodium metabisulfite to make the gold drop? Thank you

Ricardo Almeida
Shop employee - Aveiro, Portugal

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