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Organic Strength VSOrganic Flows in Copper Extraction (5 replies)

Bob Mathias
10 months ago
Bob Mathias 10 months ago

In our SX we are maintaining organic flow of 650 m3/hr with strength of 12% which is giving max. test of 6.5 gpl. Till 6 gpl copper I am getting extraction efficiency of 85 - 90%. But as soon as tenor goes further high even 6.2, extraction efficiency is dropping to 65%. Can anybody suggest me graphical representation of this phenomenon.

I am using Cytec compound.

Bill Rico
10 months ago
Bill Rico 10 months ago
1 like by KevinYoung

Check the pH of your feed before (6 g/L) and after (>6.2 g/L) as this may be the root of your problem. For every mole of Cu loaded you release one mole equiv. of H2SO4 to the raffinate; if the pH drops too much the loading efficiency starts to suffer.

Helena Russell
10 months ago
Helena Russell 10 months ago

Talk to Cytec. They will be able to sort out your issue and they are very helpful (as are BASF to be fair). But the information you have provided is not sufficient to diagnose the problem. You need to indicate your aqueous and organic flows and the Cu tenor of the aqueous feed and raffinate you are achieving as well as the pH of the feed and raffinate. Is there any other source of copper coming into extraction, for example an electrolyte bleed? Do you have an extraction isotherm with new extractant mixture and another with the plant extractant mixture for comparison? Have you changed something in stripping to make that less efficient? Again, you need to specify aqueous flows and free acid and Cu concentrations in and out of stripping. If stripping is less efficient, organic loading capacity drops.

Jean Rasczak
10 months ago
Jean Rasczak 10 months ago

Agreed, you need to supply additional information. How many series stages are you running? Individual stage efficiency may shed some light on your situation. Have you modeled the operation using Cytec's simulator? It may be a matter of mixing efficiency.

Alan Carter
10 months ago
Alan Carter 10 months ago

The equilibrium is more complex than people think, and depends on many factors.I'd recommend reconstructing the whole equilibrium curve (for your process conditions) and using both extraction efficiency and stage efficiency to understand performance of your equipment.

It appears to me, that the solution to this problem is to work far from saturation (say, 4-5 g/L copper by improving Stripping/EW as recommended or use 15-17% extractant instead of 12%). This shall bring process back to 85-90%.

Bob Mathias
10 months ago
Bob Mathias 10 months ago

Thanks for information. I have contacted Cytec. They told it will take some time to send the equilibrium curves. We have split circuit with low PLS and High PLS. Organic flow as series parallel. First it comes in contact with LPLS in E3, then HPLS in E2 - E1. Stripping efficiency is running at 58%. Advance electrolyte 58 and spent electrolyte 43.

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