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Challenges of Deep-Sea Mining

Interest in sea floor mining is increasing. A lot has been written on the advantages of Deep-Sea Mining, but not much on the basic challenges. Getting to the deep-sea floor is fairly easy, although the recent issue (June 2023) with the Titan submersible does illustrate some of the issues of coming back up.

Where does deep sea mining occur?

While most mining that has occurred to date (going back several thousand years (see “Voyage to the bottom of the sea” https://www.smartdogmining.com/topics/Voyage%20under%20the%20sea.html) has been in coastal waters current plans are to mine the deep sea on the ocean basin. This is at a depth of 4,000 - 5,000 meters (12,000-18,000 feet).

At this depth pressure is 400 – 500 atmospheres (5,900 – 7,300 psi, 400- 500 bar), and below about 200 meters depth the average temperature is 4°C (39°F). At this depth it is perpetually dark. And communications between this level and the surface is difficult. While in space we have been able to communicate with the Voyager space craft at a distance of 161 AU (24 billion km; 15 billion mi) from Earth as of August 2023. Radio signal loss (attenuation) occurs at depths of as little as 20 m below sea level. Below this depth acoustic (sound waves/sonar) is commonly used with limited bandwidth.

The best way to communicate with and control (which is way more important) is by a tethered cable. Such a cable will need to be very strong and durable. Even though we use subsea cables already they are actual quite different. While information shows that the average life of subsea cables is at least 17 years (normal design life is 25 years), that would imply that they are very durable. But these cables are not subjected to constant movement. In fact, the easiest way to damage them is by moving them, by say a ships anchor.

Then comes the mechanical components, particularly moving parts. Moving parts, particularly rotting joints are needed, even if the actual recovery system is a scoop that is dragged over the sea floor.

Most current systems are designed to hold pressure in not hold pressure out. Even in space the effort is to contain 1 bar (1 atmosphere/14.97 psi) or less in. Even current high-pressure design in refining and chemical plants are designed to contain 100 bar (100 atmospheres/1,497 psi) in.

From this perspective designing for space mining could be considered easier. Design would entail keeping 1 bar (14.97 psi) in.

This article does even begin to discuss the ecological impacts, because that is not an area the I feel qualified to talk about. But others have, which a google search will show.

 

o   40+ years’ experience in the mining industry with strong mineral processing experience in precious metals, copper, industrial minerals, coal, and phosphate

o   Operational experience in precious metals, coal, and phosphate plus in petrochemicals.

o   Extensive experience performing studies and determining feasibility in the US and international (United States, Canada, Mexico, Ecuador, Columbia, Venezuela, Chile, China, India, Indonesia, and Greece).

o    E-mail:  info@smartdogmining.com