Gold extraction from cyanide gold stripping solution

[godslavejose]

I tried gold plated pin stripping by sodium cyanide 20gram/litre and gold stripping solution of 150ml/litre company is growel stripping.
There is no problem in dissolving gold with this solution. I cant extract the gold. After dissolving the ph is showing 14. Then i add 10 gram NAOH and add zinc dust. There is no reaction taking.

Why we add sodium hydroxide?
How and why to adjust the ph?

Thanks
Jose

 

[Lino1406]

If pH = 14, there's no need to add NaOH, it's already there. What is the initial weight of pins?

 

[godslavejose]

Pins weight is 700 grams. Sir can you tell the reason why we add naoh?

 

[Lino1406]

Cyanide gold solution always contain NaOH for optimal gold dissolution and electroplating. In the case of zinc or aluminum cementation, NaOH acts as corroding agent, to expose fresh areas of metal

 

[godslavejose]

Ok sir. In this case i just add zinc dust to precipitate the gold for cementation. If suppose the ph is below 12 should add NaOH correct.

 

[Lino1406]

PH 12 may be enough. But you may add, no problem

 

[godslavejose]

Thank you sir

 

[r3arch1312]

Thank you sir

I read in officiall pappers for extraction of gold from cyan solutions, you need to decrease Ph under 11 it says" the best 10.5, and you must add H2O2 30% hydrogen-peroxyd to free-cyan's. on 2lit of solution you need to add 40ml of H2O2 and after you kill cyan than you do. cementation...in casse that you dont kill cyan in solution it will redisolve your gold again..

 

[godslavejose]

I read in officiall pappers for extraction of gold from cyan solutions, you need to decrease Ph under 11 it says" the best 10.5, and you must add H2O2 30% hydrogen-peroxyd to free-cyan's. on 2lit of solution you need to add 40ml of H2O2 and after you kill cyan than you do. cementation...in casse that you dont kill cyan in solution it will redisolve your gold again.

I read in officiall pappers for extraction of gold from cyan solutions, you need to decrease Ph under 11 it says" the best 10.5, and you must add H2O2 30% hydrogen-peroxyd to free-cyan's. on 2lit of solution you need to add 40ml of H2O2 and after you kill cyan than you do. cementation...in casse that you dont kill cyan in solution it will redisolve your gold again..

Correct sir. Thats why the expecting recovery didnt come. Thank you.

 

[Deano]

The mining industry uses vacuum to remove oxygen from cyanide solutions before zincing, this is because they work with very large volumes of liquor and they want to gat the maximum gold recovery from the solution, they use longer contact times.

In small scale the contact times are short if you are using zinc dust, any small amoumnt of gold lost to redissolution will be recovered when you reuse the barren solution with some make-up cyanide.

Always interesting to watch reactions to peroxide addition to cyanide solutions, lots of frothing as all the residual cyanide froths to destruction.

Deano

 

[yasin1987]

How and why to adjust the ph?

Hello.
Dear friend, in cyanide solution, the most important issue is the pH of the solution.
When the pH of the solution is low, the possibility of producing deadly toxic gases is high.
Especially when you want to do cementing. Because sometimes the pH of the solution drops quickly and .... !!!
Also, before adding zinc or aluminum to the filtered solution, make sure that there is no oxygen in the solution.
Because the presence of oxygen (such as nitric acid in AR) will dissolve gold or silver.
Although it has other factors, this is the most important factor that raises the pH of the solution.

 

[yasin1987]

I tried gold plated pin stripping by sodium cyanide 20gram/litre and gold stripping solution of 150ml/litre company is growel stripping.

By the way, I doubt you got the gold.
I will say the generalities of cyanide work. Of course for minerals. But that's the whole point.
Every 10 grams of sodium cyanide can dissolve up to one gram of gold.
The solution must be heated during the process. Keep the solution temperature above 40 ° C.
The pH of the solution should be between 9 and 11.5. This should always be constant during the process.
Otherwise, you either lose your cyanide in the solution or cause other elements such as copper, iron, etc. to become complex with cyanide.
To increase the pH of lime or sodium hydroxide
And to lower the pH of sulfuric acid (be careful when using sulfuric acid when you have cyanide in solution)
You must use 50% hydrogen peroxide during the process. Usually 150 drops per liter of solution ...
If you want to cement with zinc, you can also use ammonia during the process.
Cyanide works better with ammonia. However, the temperature of the solution should not exceed 65 degrees Celsius if ammonia is used. Because the probability of its evaporation increases. Do not use more than one gram of ammonia per liter.
At the end, filter the solution, raise the pH of the solution and pour it zinc or aluminum ...