Dredger sucks up the nodules and the seabed as well as silt and sand and other debris, including marine life. It destroys the oxygen whilst it washes and crushes the nodules and spits out voluminous clouds of debris, including dead marine life, which can flow for thousands of kilometres before settling again.
It then pumps the crushed nodules to a rig or ship where they are washed and the spoil is deposited back into the sea. The spoil is very near the level where most marine life - algae, plankton, fish, seals, dolphins, sea lions, sharks and whales - live and thrive at 80 to 200 metres. The deposits will land on bottom feeders such as dab, plaice, sole, turbot, crabs, clams, lobsters, langoustines, octopus, etc. Some 40% of humanity relies on these resources to survive. The whole process is energy intensive, more so than wind and solar can produce on site - net zero my a..s. But all is OK, eh? For you and yours there's no problem, profits and money are to be made. Drive an EV and you'll save the world.
As part of its plans, Royal IHC has designed a 16-metre-wide robot and built a three-metre test vehicle - called Apollo II - which would be able to gather about 400 tonnes of nodules in an hour and pump them aloft. Over two weeks’ operation, more than 100,000 tonnes could be removed this way. And after operating for 25 to 30 years – the anticipated limit for an ISA extraction licence – about 10,000 square kilometres of the seabed could be strip-mined.
The test vehicle is only 1/5 full scale. There will be many full scale versions made. You do the maths. It's one rig - of many!