How to adjust the pH ?

[future gold refiner]

How to adjust the pH of a basic (around 10) thiosulfate leaching solution.
[my solution rises with time so i have to lower it ]

rise is logic : ammonium hydroxide (called ammonia solution)
but to lower?? : sulfuric acid ? -> but does it decomposes the thiosulfate-ion ? or not? or only when it´s not diluted ?

thanks for help

 

[Lino1406]

environment will decompose Thio to sulphur. Use
dilute acid for solution not to become acidic. Do
experiment on small sample, then work proportionally

 

[Juan Manuel Arcos Frank]

Here is a trick come out from the photo process bussines:

Since sodium thiosulphate is common fixer then we use glacial acetic acid to down pH,you can use vinegar but you should use a lot because vinegar is 5% acetic acid.

Hope it helps.

Best regards.

Manuel

 

[Lino1406]

If you use acetic acid for that, avoid using
formaldehyde, sometimes being used to augment
recovery (in addition to caustic). Otherwise,
you have a bomb!

 

[future gold refiner]

i thought about acetic acid but does it not converts the coppper amine (which is required for gold leaching) to copper acetate which is not active for gold leaching?

 

[Juan Manuel Arcos Frank]

Good point, Herr Future Gold Refiner...it depends on how much acetic acid you need to achieve your desired pH level level.Sodium thiosulphate used as photo fixer is about 5 pH.Anyway,you have many options...you may increase thiosulphate concentration to low pH to 5....you may change copper sulphate instead of copper amine or you may use another thiosulphate leaching process.

As you see,there are many options and today,more than ever,emphasizes the truth written by GoldSilver Pro (GSP,Grand Master of our Brotherhood) with golden letters:"THERE ARE MANY WAYS TO SKIN THE CAT"

Gott segne dich

Manuel