Laboratory Testing & General Mineral Processing Engineering

Laboratory Testing & General Mineral Processing Engineering

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How much cyanide is required to dissolve gold (2 replies and 1 comment)

D
Donard ZM
6 years ago
Donard ZM 6 years ago

Hi, I fail to know exactly amount of sodium cyanide needed to leach the gold ore with a certain amount let's say 5 ppm,please help me a nice calculation relates the amount of gold in ore, capacity of leaching tanks. Thanks.

Y
Yves
6 years ago
Yves 6 years ago
Like
1 like by David

The amount of cyanide cannot be calculated. What you have to do is too make sure you are keeping a pH above 10.5 with lime or caustic soda and maintain a sodium cyanide concentration of 0.35 g/l or 0.035%. The gold dissolution rate is driven by the amount of dissolved oxygen in the slurry. If the oxygen is less than 4mg/l so you can boost it by injecting air into the slurry or by addition of hydrogen peroxide. There are no hard formula to run leaching it all depend of the ore treated. 

N
Nurettin
6 years ago
Nurettin 6 years ago
Like
1 like by David
  1. what is the gold minerals? 
  2. partical size and crack rate (permeability of particals)?
  3. pH situation? ( S content and types? How much CN you will lost?
  4. Cu content? How much CN you will lost? 
  5. pH arranger effects? Ca may be gypsum May be etc.

if no H+ ion, no metals except gold and solution is touching gold surface easly you will need minimum 2 times ppm CN and minimum 1 times ppm O2 for 1times ppm gold. 

it is not the easy to determine the values for 5 topics. But you have to.

easiest way is making bottleroll and colon tests for different parameters and then evaluate the ore habits. Then you can decide the CN ppm for the decided ore situation.( partical size, alteration, pH arrangement etc)

Y
Yves
6 years ago

I will tend to disagree with the suggestion above. The reality is you cannot use Stoichiometric calculation to complex ore in real leaching plant. If you had some experience in that field you will note write the above. Of course copper can be an issue and you just have upper the cyanide content to take care of it. Generally in CIP circuit the pH is maintained above 10.5 and the sodium cyanide to 0.3 to 0.4 grams per litres and on vat leach around 1.0 grams per litres. Hydrogen peroxide has been proven to accelerate the gold dissolution.

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