A handful of dry flocculants powder spread along the offending seal and lightly wetted forms a gel seal that can be quite effective.

But you really need to look at your priorities. Significant gold losses cannot be held over till the next quarterly shut. We fix them the same week. A little loss in throughput or running time is more than compensated by the reduced gold loss. Who "wears the pants" on your plant - the metallurgists or the maintenance guys? 

Need more information, sounds like you’re in the electrowinning area, is that correct, if so how does the gold get to the tails? The only other places could be Elution or C.I.L tanks. Even Elution should be directed to tanks as should electrowinning area.

If this is becoming a constant problem, then it's really a symptom of the problem,
Check the specs of the valves. Confirm they are correct for the application.
Check operating procedures are correct and being followed, Cycles are correct that there's no undue pressure causing these problems.
Have the operators kept it all clean and lubricated, Prevention.
Valves wear and fail but shouldn't be that often.

Is there sediment or rubbish getting into the system that prevents the valves from closing? Tanks and pipework drained and flushed. Check it's not a scaling problem. Brainstorm with Supervisors and operators, find the problem and symptoms will disappear.

It is like that one crew in favour of using floc and another crew prefer fine dirt, but we sure tried them all. It seems that sealing with floc can have quite some downside effects on carbon as seen in a lumpy formation from kiln discharge oversize chute carbon bag.

It would be ideal if the faulty valves/gates can be fixed immediate after they are spotted or at least during the time the cell is pulled. How do your sites manage maintenance work in adsorption area? As far as I know there would be safety concerns, isolation limitations, as well as production loss pressures, these are the facts that stop us from getting pump cell system back to its designed efficiency. Oh, I nearly forgot that the curing time required for some repairs before they can be put back to service can also put us off.

Interesting discussion! The worst thing that can happen is the situation where the feed valve going to the tail tank (in a carousel circuit) leaks thereby causing high dissolved gold losses to residue. This can normally be detected by a spike in solution tail gold values. Immediate action should be taken to seal the valves. In some instances where the feed pipe discharge is not visible a drain valve can be installed at the bottom of the bend which will give a visual indication of any leak.

Thanks for the background of Pump Cell Circuit (a carousel circuit).
Yes, having those leaking detection valves on bend sections of feed pipes is very helpful for detecting if high gold bearing slurry passing to tails when some feed launder dart valves or knife gates are passing. We have got them in system. I am more interested in the solution for the head cell to tail cell gate valves, they are difficult to seal when passing, and hard to detect when both side of cells are online. It seems the best time and the only time to be able to check and seal them is when the head cell is pulled or cell slurry level is lowered. Sometimes when all both valves seal, the seal can be undo after pulled cell is refilled and brought back online.

It seems that the valves you have are not suitable for the application as suggested. You should speak to the vendor of the cell; they should be able recommend the ideal valve for your application. Most vendors provide technical support for their product and should assist you.

The solution to detecting passing valves is to use a double block and bleed arrangement. The bleeder drains the area between the two valves, to prove that no fluids are passing either direction. If anything comes out of the bleeder, it is time to fix the valves.

Since these valves are handling suspended solids, rubber sleeve pinch valves may be the right type of valve. Red Valve is a company that is a well-known maker of these pinch valves. Contact them to see what kind of products they can retrofit you cells with.

Would you mind sharing the type of pump cell circuit that you have and the brand of valves that are causing problems?Are these valves the same type/brand as initially installed or were changes made by operations/maintenance?

Did you see the report that I did on the Pumpcell valves about 2 years ago at your plant? There were a lot of photos and some suggestions on how they could be optimised. Most of the intertank valves have been replaced or refurbished, but they still require maintenance of the replaceable seals from time to time. The tank to tails valve were all the old original valves and in very bad condition. I can resend this report if you have not seen it.

Yes I have just read that report recently. There will still be a lot of work to do to get these valves sealed properly!