↑ The belt sluice will rotate in this direction.
↑ This is the belt. See the red arrow, it can trap gold.
↑ When it’s working, the water flow in red direction, the belt sluice rotate in blue direction.
↑ So when it’s working, the nugget gold and big sand move in the blue direction. The small gold and sand will move in the red direction.
Why need a belt sluice?
When raw material has clay, it will be slurry after washing. Slurry is not good for concentrator extracting gold.
Belt sluice can take cleaner slurry and concentrate up to concentrator, and dirtier slurry go down to carpet sluice/ vibrating sluice/ hydraulic riffles.