Deep Ocean Mining Then and Now, a 1978 Perspective and Todav's Realitv

摘要

In early 1978 Ocean Management Inc. (OMI), a consortium comprised of INCO Ltd. of Canada. AMR, a consortium of West German companies, DOMCO, a Japanese consortium led by the Sumitomo family of companies, and SEDCO, an ocean drilling company based in the USA, successfully completed a pilot mining test (PMT) and became the first organization in the world to mine manganese nodules from the deep abyssal plains of the Eastern Equatorial Pacific. Flying high from their success, this group of young enthusiastic engineers, technicians, and operators from around the world saw a bright and unlimited future in deep ocean mining. Little did they know then their vision was not to become reality for another thirty years and even then materialize in a form substantially diferent from what they had envisioned. Much has changed since 1978 including the switch from "manganese nodules" to the more appropriate"polymetallic nodules" designation for this potential ore. This paper presents a "then and now" perspective on deep ocean mining. in 1978, operating in excess of 5,000 meters of water, OMI's deep ocean miners conducted PMT operations from the Drill Ship SEDCO 445. They had more than one million pounds of 9-5/8" drill pipe suspended from the rig floor to down near the seafloor. They utilized multiple one thousand horsepower in-line submersible pumps as the primary means to bring the nodules to the surface. A very simple, low horsepower, passively towed collector was attached to the riser via flexible rubber hose. The collector was used to separate the nodules from the cohesive sediment of the seatloor and introduce them into the riser for the twenty minute transit to the suttee. Once at the surface, the water and unwanted sediments were discharged overboard, and the nodules were transported via conveyors to holds and storage containers on deck. Back in 1978, nodules with a combined of nickel, copper, and cobalt content of only 1.5% were considered ore grade. The OMI mine site was located in the Clarion-Clipperton fracture zone approximately one thousand miles Southeast of Hawaii. By comparison, today's ocean mining companies like Nautilus Minerals, Inc. and Neptune Minerals, Pic., are not interested in nodules at all. but are instead alter high grade seafloor massive sulfide (SMS) deposits containing gold, silver, and other high value materials. Their mine sites are in only～1,500 meters water depth and are located much closer to land within the EEZ of several island nations in the Western Pacific. The mining approach for SMS deposits is different than the recovery methodology for polymetallic nodules. SMS deposits resemble underwater versions of hard rock deposits on land, the mining equipment being developed is generally large, high horsepower, self-propelled, sophisticated rock eating and crushing systems. Mining systems containing multiple independent collectors feeding central crushing stations and single risers are being evatuated. On the threshold of reality, deep ocean mining of 2009 is a far cry from what the now gray-haired, mostly retired, ocean miners of the late 1970s saw in their vision of the future. However, like the deep ocean miners of the 1970s, today's young, enthusiastic, high tech ocean miners are breaking new ground and developing new technology and equipment not envisioned thirty years ago.