Deepsea Mining: Heading Back Down to 15,000 Feet
Authors: Heydon David 
Published: April 2012

Paper

On 13 March 1874 the crew of the British research vessel HMS Challenger, on thefirst great oceanographic expedition of modern times, hauled in from a depth of15,600 feet in the Pacific Ocean a trawl containing the first known deposits ofseafloor manganese nodules. We can but imagine the surprised look of the ropemakers with a budget requisition in the 1870's for a rope ‘umbilical’ &gt;15,000 feet (4,500 metres) to deploy sampling tools to the ocean deeps. Analysis of the samples in 1891 showed the Pacific Ocean nodules to containimportant metals, including nickel, copper and cobalt. Subsequent samplingdemonstrated that nodules were abundant throughout the deep regions of thePacific.

Jump 104 years to 1978 when an ROV was deployed to 15,000 feet (4,500m) andsuccessfully "harvested" manganese nodules from the east Pacific Ocean.

At that point the deepsea mining industry far exceeded offshore oil & gasin depth of operation, ROV technology, pumping and riser deployment. Thedeepsea mining industry however was ‘still born’; as at that time nointernationally recognized regulatory framework was in place to provide thesecurity of tenure necessary for commercial enterprises to invest further inthis activity.

Fast forward another 30 years to 22 July 2011 the date which marked there-emergence of commercial interest in these vast seafloor deposits with thegrant of the first ever contract by the International Seabed Authority (" ISA")to a commercial enterprise over a 28,900 sq mi (75,000 sq km) area inInternational Waters.

This paper revisits the potential for mining these vast deposits in light oftoday's commodity prices and technological advances, including highlightingareas where the offshore industry and contractors can participate. It outlinesopportunities for R&D and product/equipment development to support thisemerging industry as the mining industry seeks to regain the lead of operatingcommercial activities on the seafloor at 15,000 feet (4,500 metres).

The economic potential of the vast deposits of nodules on the deepsea abyssalplains was recognised by several mining companies who began preliminaryinvestigations in the 1950's. Others started R&D programs in the 1960'sculminating in peak activity in the 1970's with over 20 companies involved in 4consortia conducting short trial ‘mining’ at depths of 15,000 feet. Amongst theships used for these trials were the SEDCO 445 and the Glomar Explorer, thelatter of which was designed as a ‘heavy lift’ vessel.

Several groups deployed passive mining tools which were attached to the riserand ‘powered’ by the movement of the ship and riser through the water withimprecise navigation on the seafloor. The dynamics of ‘dragging’ a 15,000 feetthrough the water column as part of one's operation would scare most engineerstoday studying riser design and straking; yet engineers in the ‘70's went aheadand built, deployed and operated these systems albeit without the fear ofmassive pollution in the event of a failure which is clearly on the minds ofriser designers in offshore oil fields.

One group built an ROV ‘miner’ incorporating Archimedes screws instead ofcaterpillar tracks for propulsion in the soft muds of the abyssal plains(Figure 1). Surely this in 1978 was the first commercial ROV operating in15,000 feet (4,500 metres): well ahead of its time!