Key points
- Inside the collector vehicle, nodules and sediment pass through pumps into a hopper, where differential flow rates tumble the nodules so sediment separates from them at the seabed.
- Because nodules are heavier, they sink to the bottom of the hopper while 95-98% of sediment particles stay suspended in the water discharged out the back of the vehicle, returning to the seafloor.
- The remaining 3-5% of sediment travels up the riser to the surface vessel, where cyclones separate it before it is released into the midwater.
- Allseas is developing and testing a Hopper 2.0 that enlarges the hopper and improves flow to give nodules more time to separate from sediment, building on lab trials that optimized flow rates and pump sizes.
