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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CIP tanks not flowing (16 replies)

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Philipo
3 weeks ago
Philipo 3 weeks ago

Hello Guys;
I work at a CIP Gold processing plant. Currently the CIP tank has a problem with the slurry flow. There are 9 tanks, 2 leaching and 7 adsorption. Slurry from some tanks donot flow to the next tank, like from tank#7 to tank#8. Besides the difference in density, what other factors could there be that stops the flow. The screen valves and the pipes are all fine.

Thanks

David
3 weeks ago
David 3 weeks ago

Sanding? A cyclone plugged for a while and now those coarse are trying to exit the system? A large piece of scaling came off the tank walls and is blocking the exit? 

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Philipo
3 weeks ago
Philipo 3 weeks ago

Thanks Dave. i understand now the problem. I will check for that.

Thanks, much appreciated.

 

David
3 weeks ago
David 3 weeks ago

please come back let us know what you found

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Philipo
3 weeks ago
Philipo 3 weeks ago

Hey Dave.

I checked the sanded material. It reports 60-65%<75um. But it is of a a huge quantity. It settles easily. It can only be transfered through compressed air to the former tank during carbon transfer. Now we are trying to lower the tank and lower the slurry denisty so as to flow easily, but not that much good. Is there any other means of taking it out.

Thanks

SmartDog
3 weeks ago
SmartDog 3 weeks ago

Shut the tank down and bring in some vacuum trucks and vacuum it out.  Alternatively shovels and buckets.  Sorry, but once you get large material in the only solution is to dig it out.

Unfortunately, with the "modern" tendency to run cyclones at a high density feed this is what happens.

An operation I did some work with about 10 years ago was running their cyclones at 50% solids and where getting up to 75 mm solids in their tanks like you.

Saved on capital, but required digging out about every 6 months.

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Philipo
3 weeks ago
Philipo 3 weeks ago

It seems like this is the only solution left. We will proceed with that. Appreciate all for your efforts and helpful ideas.

Thanks

David
3 weeks ago
David 3 weeks ago

Just reducing density will cause even more settling in your tanks. Just like a thickener works better if you dilute its feed.

I found the best way to "un-sand" anything is to increase the density of a finer slurry. This is temporary, for maybe a 12-hour shift. You would do this by reducing your tonnage (20 to 30%) to improve the grind but also thicken your system by cutting water where you can. Yes, your cyclone efficiency will be reduced but the lower tonnage will secure the finer grain. The result is the fine and thick stream will carry away the coarse sand from your tanks.

No need to shut down production.

If you normally operate with a 40% density leach circuit, I will try 50 or 55% (if you can... if it runs) for that shift.

P
Philipo
3 weeks ago
Philipo 3 weeks ago

I got the idea Dave. We have started operation at lower tonnage and pumping 48-49% solid material to CIP. I will update you on the results. Thanks again

David
3 weeks ago
David 3 weeks ago

While you do this, you can help the process by poking an air lance in the area where your coarse has settled. This will lift them up and help carry them away in the finer & thicker slurry.

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Philipo
3 weeks ago
Philipo 3 weeks ago

Okey David. High flowrate compressed air is running into the tanks. Let me update you in the coming 4-5 days.

Thanks

David
3 weeks ago
David 3 weeks ago

be careful to not perforate (sand blast) a hole at the bottom of your tank

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Philipo
2 weeks ago
Philipo 2 weeks ago

Sure. I will.

r
rob riggir
2 weeks ago
rob riggir 2 weeks ago

Hi Philipo,

The above suggestions are good. Some others are;

  • replace the airlance with a submersible pump that can be moved to the areas where the coarse material has settled. Sand blasting a hole in the tank is a REAL issue.
  • Check that the tank agitator is designed for the PSD that is entering the tank. The agitator MUST create full suspension, therefore no settling.
  • Check that the tank screens are the correct size for the PSD entering the tank.

Cheers,

Rob Riggir

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Philipo
2 weeks ago
Philipo 2 weeks ago

Hey all;

Thanks all for your help. Now the system is getting better and stable. Once we start the ball mill at a lower tonnage and finer material, then tanks are getting unsanded, which eases all the problems. The agitators wont alone mix the slurry, needs sufficent air as per the design. But now looks fine. Thankyou again for your beautiful ideas.

Appreciate it.

Philipo

David
2 weeks ago
David 2 weeks ago
r
rob riggir
1 week ago
rob riggir 1 week ago

Hi Philipo,

Just a further comment on tank agitators;

Tank agitators should be designed to fully suspend the slurry in the tank by themselves and also to re-suspend settled solids after a power supply cut of say, 4 hours.

Using compressed air to assist the agitators is not a good option as it is expensive and will abrade the activated carbon in your adsorption tanks.

The best option (assuming you have the correctly sized motors and gearboxes) is to replace the agitator blades which is not expensive. You may even get improved recovery due to the better suspension which can result in less tanks dead spots and bypassing.

I have an associate here in Perth who can investigate new agitator blades if you wish.

My contact is rob.riggir@gmail.com

 


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