Hydrometallurgy: Leaching in Heap, Vat, CIL, CIP, Merrill–Crowe, SX Solvent Extraction

Hydrometallurgy: Leaching in Heap, Vat, CIL, CIP, Merrill–Crowe, SX Solvent Extraction

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Gold stripping from activated carbone (3 replies)

A
Ahmed Zaky
7 years ago
Ahmed Zaky 7 years ago

Hello , I want to make stripping but i want details about ( optimum CN and NaOH concentration and also alchole , temperature ) and which is better ? heating stripping solution with carbon directly or circulate solution through carbon, ratio of carbon to solution

R
Richard S
7 years ago
Richard S 7 years ago
1 like by David

If you are setting up a carbon strip circuit, I suggest that using an atmospheric Zadra system is likely the simplest and least expensive to set up.  In this style system the strip solution is passed through the carbon in a container and subsequently passed though an electrolytic cell to remove the stripped gold.  You can use steel wool as the cathode in the cell.  Ultimately when the wool is loaded, you will need to remove it from the cell and smelt it to recover the gold.  The strip solution will be heated to near boiling temperature and can be 2% NaCN and sufficient caustic to keep the pH at >11.  The strip solution can be recycled but you will need to maintain the pH and the free CN strength by reagent addition as necessary.  You can use alcohol which might be helpful in the strip and might be effective at slightly lower temperature; however, I would advise against it as it can and will be a significant fire hazard in addition to the chemical hazard.  You do not need to have a fast solution circulation through the carbon and can use a horizontal container or columns to accomplish the stripping.  Just be mindful that you have good solution contact with the carbon.  An upflow column may be the simplest for you initially, utilizing screens to keep the carbon in place.  You must have the strip solution as near boiling as possible to speed stripping.  Solutions at 150F will remove copper but not significant gold from the carbon.

A
Ahmed Zaky
7 years ago
Ahmed Zaky 7 years ago

thanks for reply , i want some points to be  explained  

1- ratio of solution to active carbon

2 - composition of electrolytic cell and if it depends on volume of solution

3- how can i circulate solution through carbon automatically all duration of stripping 12 hours ( name of instrument) and how many circulations enough to make sufficient strip  

J
Jorge
7 years ago
Jorge 7 years ago

It is important to evaluate the elution process because it has an impact on the electrowinning process. For example the AARL system designed to operate in open circuit creates 7 to 8 bed volumes of solution. The addition of alcohol or glycols improves the elution rate. The solution flow rate to perform the elution ranges from 2 to 4 bed volumes per hour. The temperature depends on the elution system. You should evaluate it. The pH should be considered between 10 to 11.5.


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