Usually you recycle the coarse oversize through the plant with the feed. It cuts down the wash feed rate but this is preferable to having clay balls carrying gold through the tails.

The water requirements have to be found by experiment, you usually have a spray bar inside the trommel to help with the clay break down.

Adding clay breaker helps somewhat but usually not enough to pay for the chemistry and it will bite you when trying to get clean water back from the tailings dam.

I assume that you have a 300mm wide ring at the bottom of the scrubber section to retain the feed.

You would want to have 4 slotted 150 wide lifters on the ring to keep the oversize moving through the circuit.

You usually have 150mm angle iron longitudinal lifters in the scrubber section, allow 1 lifter per metre of circumference.

What you want is to run the scrubber as a semi SAG mill with the high pressure spray bar adding the majority of the water in the circuit.

Hello Alex - Did you get your clay problems solved?

Hello Deano - Interested in your observations about a prewash for heavy clays?

Do you provide tech services?

Rob

rslavik@tanzaniangoldfields.com