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 EW circuit low efficiency (2 replies)

H
Hamid2017
6 years ago
Hamid2017 6 years ago

Hi guys

In a gold plant, the EW circuit efficiency is low, it is suspected that it is due to higher concentration of chlorine in the solution. any article or plant experience addressing this issue and suggesting any solution? your help will be highly appreciated.

 

http://www.soutex.ca/

T
Emadi
6 years ago
Emadi 6 years ago
Like

 

Concentrations < 0.5 mol m-3 (< 102 g m-3) of AuCl4- and AuCl2- ions in 1 kmol HCl m-3 aqueous electrolyte were reduced to elemental gold in a packed bed cathode of 2-3 mm graphite particles, in an electrochemical reactor incorporating a cation- permeable membrane and operated in batch recycle mode. Depletion to concentrations < 5×10-3 mol m-3 (< 1 g m-3) appeared to be mass transport controlled at an applied potential of 0.53 V (SHE) and occurred with < 4 F (mol Au)-1 and specific electrical energy consumptions of ca. 400 kW h (tonne Au)-1. However, atomic absorption and UV spectrophotometry established that, as the ([AuCl4-] + [AuCl2- ]) concentration decayed, the [AuCl2-] : [AuCl4-] molar ratio changed. A (multi-step) mechanism for reduction of AuCl4- ions is proposed, to explain this behaviour, in terms of changing overpotentials for AuCl4- and AuCl2- reduction as total dissolved gold concentrations decreased.

http://ecst.ecsdl.org/content/2/3/317.abstract

Meet.-Abstr.-2006-Kelsall-924.pdf
D
Deano
6 years ago
Deano 6 years ago
Like
1 like by David

Are you getting high values in the strip liquor so that the problem is only related to the actual EW section. It is often the case that these types of problems are caused by poor values in the strip liquor, it is pretty hard to be efficient if the strip liquor values are low.

Assuming that your strip liquor values are reasonable and your electrical connections have checked out OK and that you are drawing the appropriate amps compared with previous practice, then the usual cause of problems is related to the presence in the liquor of metals in solution.

The usual culprits in this case are copper and iron with iron being the worst offender. Usually but not always iron complexes in these cases will colour the strip liquor a light to dark ferric colour.

The only easy solution to the running of such liquors is to push the amps up so that you can beat the tendency of the iron ions to bounce from +3 to +2 valency and back again between the electrodes.

Even nicer if you can explain the problem to the geos and have them send the problem ore to a separate stockpile.


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