emphasis will be given to the first three. One can subjectively give varying degrees of technical risk associated with the functions and subsystems listed. As an example, a high degree of reliability associated with the mobility and nodule pick-up performance must be achieved so that confidence can be obtained in the designed production rates.

It will be noted that many of the items listed have a strong operational slant. That is, the success of the test relies as much on operational procedures previously established or acquired as it does on the design and technology applied to the system.

The list given is not complete but does contain many of the most important items. Some of the items are associated with efficient sediment separation and slurry lift. The bottleneck to production rates is primarily the slurry production of the lift pipe. Here sediment separation at the ocean floor is important because every ton of clay lifted reduces, in an equal amount, the total tonnage of nodules lifted. While test and analysis ashore have provided the operators with respectable engineering data, only largescale tests at sea can provide the accuracy desired.

The design of the mining system comprising the ship, the pipe and the nodule collector draws some technology developed in offshore drilling as well as government sponsored ocean R&D programs such as the Glomar Challenger and Glomar Explorer. In the interest of costs, the ocean mining industry is using existing surface ships modified to handle the pipe and the nodule collector. Both International Nickel and Deepsea Ventures have scheduled their initial operations in 1977, while Kennecott and Lockheed are looking toward 1978 and 1979 for their initial test operations. Some of the tests will be conducted in previously selected mine sites.

Actual operation to determine mining costs

All systems are being designed to mine at a slow speed of a few knots. The practical operating speed depends upon a number of parameters such as pipe stress and fatigue, hydrodynamic drag and stability as well as the total system dynamics. Included are the dynamic characteristics of the nodule collector at the ocean floor water-clay interface as well as the nodule collection and clay rejection efficiencies. It is apparent that the tests will provide the necessary data for design modifications and improved operational procedures.

The cost of the feedstock to the processing plant is a December 1976

The above are not independent variables. As an example, reliability, maintainability and costs are interrelated as well as many of the other factors.

Preliminary calculations show economy of scale. That is, a 3 million tpy mining ship may produce nodules with measurably less cost per ton than one with a production of a million tpy. The number of crew required is almost independent of ship size as well as miner capacity. Energy requirements generally increase as the two-thirds power with size. These types of scaling factors may not hold for a mining ship because it will be operated differently than other ships. Therefore, it is the operational characteristics that may have the greatest influence upon design.

All preliminary designs and prototype systems tested at sea will exhibit characteristics that will require modifications. Not all the characteristics that lead to inefficient operations will be immediately recognized. For this reason, several trials at sea over a period of a year or so will be necessary. At each step, modifications will be made to provide better operational data during the next step. The cumulative knowledge gained will then be incorporated into the initial operational model.

Nodules embedded in heavy "grease"-like clay

It should be emphasized that the manganese nodules represent somewhat of a unique ore deposit, a thin horizontal strata approximately 2 in. thick, extending for many miles. The nodules are friable, and 50 percent by volume pores, and are imbedded to approximately half of

their vertical dimension into the bottom clays. These clays are very soft and have some of the physical characteristics of heavy grease. The efficiency of the system is not only set by the percent of the area that can be navigated by the nodule collector and the percent of the nodules within that area that can be recovered but also by the quantity of clay that is recovered along with the nodules. The pipe represents somewhat of a production bottleneck; for most efficient production, it should be operated close to the maximum design capacity.

Fig. 4 is a simplified chart of the so-called nodule belt. Only a few of thousands of nodule sitings are listed. There is considerable variation in nodule coverage as well as nodule grade of ore, even though the area is extensively covered with nodules. Testing of the prototype systems by the different mining groups will most probably be accomplished in their prime mine sites. Indicated also in

fig. 4 is the claim area of Deepsea Ventures. Most probably the other activities also have chosen mine sites in the eastern portion of the nodule belt since distance of the mine sites from the processing plant on the U.S. West Coast is an important economic consideration. Prior to the deep ocean deployment, shallow water tests (600 to 6,000 ft) close to the West Coast will probably be conducted for initial checkout and crew training. Any major deficiency can then be more easily corrected because the mining ship is close to a supply and maintenance base.

Fig. 5 is a reproduction of a chart prepared by the research team of Horn, Horn and Delach at the Lamont Geological Observatory of Columbia University. Of particular interest is the light area called Siliceous Ooze running from south of Hawaii to south of Baja California; it is labeled siliceous and biogenic on the chart. As previously stated, these clays are somewhat unique since they are physically very weak. The shear strength of these clays varies from about 4 to 2 psi. The dredge head or miner must, therefore, be designed light enough to prevent sinking in these soft sediments. These soils are not frictional soils as found on land, but instead are almost completely free of the fine grain-like sand particles that are found in the turbidites or ice-rafted sediments. Practically all the particles are less than one micron, about half of which is composed of biological remains. The water content is very high-one to three times the solid content. When dis

Approximately 90 percent of the nodules at any location are on the ocean floor surface, so the dredge head must be able to scrape the ocean floor within close tolerance over a width of 25 to 50 ft or more (see fig. 6). The dredge head must be carefully designed so that a minimum of clay is picked up with the nodules or, if too much is picked up, it is discarded prior to pumping to the surface.

From the previous discussion, it can be envisioned that there is a great variability in nodule size, abundance and ore grade as well as soil strength and ocean floor topography. The dredge head must be designed to provide reasonable production rates and at the same time navigate the ocean floor in a reasonably prescribed manner, avoiding obstacles and abrupt changes in terrain. Therefore, one of the primary functions of the mining system is accu

Fig. 7. Station keeping system. A transducer on the ship hull obtains distances from transponders several miles apart. The information is fed into a computer that commands the ship's propulsion and thruster systems, allowing the vessel to stay within a few feet of a prescribed course

rate station keeping (see fig. 7). One means for accomplishing this is basically the dynamic positioning system developed in offshore drilling; it is being used extensively by the offshore oil industry. A sonar transducer on the ship hull obtains distance from transponders several miles apart. The information is fed into a computer which then commands the ship propulsion and thruster systems allowing the ship to accurately navigate within a few feet of a prescribed course. It is important that the deviations December 1976

Fig. 8. An operational mining system will require vessel lift capabilities of 2 to 4 million lb or more. Illustrated are lift capabilities of several ships for different depths of water

The second important capability of a mining system is the ability to lift heavy loads. The prototype systems require between 1 and 2 million lb, while the operational system will require 2 to 4 million lb or more (fig. 8). Until recently, drill vessels and crane barges had capabilities of 1 million lb or less. The Sedco 445 will have approximately 11⁄2 million lb, while the Glomar Explorer has an 18 million lb capability. Therefore, the state-of-the-art can provide all the pipe lift required. Another characteristic required is that the pipe system be gimbaled to allow the ship to pitch and roll while the pipe remains relatively vertical. This places less stress on the pipe, lengthening the usable life by limiting fatigue.

The overall efficiency is made up of three elementsminable area, sweep efficiency and mining efficiency. The design of the total mining system will influence all three factors. The types of terrain that can be navigated by the dredge head will determine the minable area. The navigational accuracy of the dredge head will determine the amount of overlaps or gaps in the covered area. The percent of nodules picked up by the dredge head on any one pass will determine the mining efficiency. Estimates are that the first systems will pick up about a quarter of the available nodules and that, in time and with improvements, one could expect the efficiency to approach 40 to 50 percent. The initial large-scale test now planned by the industry will provide the productivity and cost figures required to determine the cost of the feedstock to the processing plant.

Legal environment will affect investment pace

The large-scale tests of deep ocean mining systems will be conducted during the next three years, 1977-1979. Large scale means from one-fifth to full designed production rates. The expenditures during this period of time for each consortium group can vary from a low $20 or $30 million to as high as $75 million or more.

Based upon the performance of their respective mining system designs, each industry group will be in a position to make decisions on the next step. This can vary from $300 to $600 million and involve the processing system and its infrastructures as well as the transportation and full scale mining system. However, it should be stated that the mining industry is carefully following the Lawof-the-Sea activities as well as U.S. legislation prospects and will speed up or slow down its investment pace as dictated by variables of the legal environment. The minimum investment by the American industry in the next 5 to 7 years could be approximately $2 billion. It should be emphasized that the technology is here; the large scale tests will provide the engineering, operational and economic confidence. Hopefully, the U.S. government can provide a favorable legal environment to allow this potentially very promising business to be established by providing a favorable investment climate.

Conrad G. Welling, manager of ocean mining for Lockheed Missiles & Space Co., spent 18 years in the Navy before joining the company in 1959 as director of operations research studies on various classified ocean system and space system programs. In 1965, he assumed responsibility for technical direction and market development of ocean mining and exploration programs.

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Deepsea Venture Group

The Deepsea Venture group is composed of U.S. Steel and Union Miniere of Belgium, with Deepsea Venture under contract as project manager. The activity is under the direction of John L. Flipse, president. The group has essentially completed its tests of the dredge head on land in a simulated sea floor test pit. Previously, in 1970, Deepsea Ventures demonstrated a nodule mining system on the Blake Plateau off the Florida coast in about 3,000 ft of water. Although the nodule and sea floor characteristics are different than the Pacific nodule belt, the test proved the ability to collect nodules and air lift them to the surface. Deepsea Ventures has conducted extensive exploration of the nodule area and, in particular, the mine claim site the company has announced. This has been accomplished with the R/V Prospector, a well-equipped oceanographic vessel.

Current plans involve the conversion of an ocean ore carrier (the Weser Ore, a diesel-driven 560-ft vessel) for the mining test platform. The dredge head is an ocean bottom screening and collecting device connected to a near vertical pipe. The system is towed through the water at a speed of from one to three knots. A 27-ft wide by 34-ft long moon pool or center well will be installed amidship to handle the pipe and dredge head. Thrusters fore and aft will provide the precision navigation capabilities required and long, base-line acoustic navigation will be employed. The pipe will be handled hydraulically from a gimbaled platform. Other modifications will include pipe and dredge handling equipment aboard ship, air compressors for the nodule air lift system and cargo holds and distribution systems for handling the nodules. Quarters for an additional 30 people will be provided, and they will handle the complete mining system.

The system tested is approximately one-fifth scale. Present plans call for initial test in early 1977. The group has not announced planned operations beyond these initial tests or the time scale of the full production system.

International Nickel Group

The Inco group consists of AMR-Metallgesellschaft Preussag, Salzgitten, Germany; Domco-Sumitomo companies and other Japanese firms; Inco Ltd., Canada; and Sedco Inc., U.S. The basic philosophy of the organization is the maximum use of the technology of the participants to accomplish as much "in-house" as practical. The project management is under Ocean Management Inc. of Bellevue, Wa., and directed by John L. Shaw, president.

The exploration program is being carried out by the R/ V Valdivia, an excellently equipped ocean exploration vessel. It is owned and equipped by the government of the Federal Republic of Germany and staffed by a German crew. The scientific crew is drawn from the participants' staffs and rotated as appropriate for the talents needed. The prime tools are free fall samplers with camera, box cores and underwater TV. The R/V Valdivia has a narrow beam depth recorder, low frequency profiler, satellite navigation, chemical analyses facilities and seismic equipment. Data reduction can be ac complished aboard, except for a few computer-based operations.

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The large-scale tests at sea will be conducted with an ocean floor nodule collector towed from the long vertical pipe on the ship. Various collector designs have been designed and tested in a local facility built for the purpose. Initial test at sea with the collector head minus the pipe have been made. The Sedco 445 was chosen for the large-scale test.

The planned operations are for the fall of 1977. The primary pumping method will be the use of submerged hydraulic pumps with a 9 5/8-in. pipe string reaching to full depth. Air lift will also be tested. The Sedco 445 is to be converted to use a special hydraulic pipe lifting system with heave compensation positioned on a gimbaled platform. The ship has a dynamic positioning system employing thrusters both fore and aft. The ship has a length of 445 ft, a beam of 70 ft and a moon pool of 37 ft diam.

The Kennecott Group

The Kennecott group consists of Rio Tinto Zinc and Consolidated Gold Fields of Great Britain, Noranda Mines of Canada, Mitsubishi of Japan and Kennecott Copper of the U.S. As is the case of the other groups, the consortium has attempted to bring together as much capability as possible to provide the know-how required for the venture. The group is under the direction of Marne A. Dubs.

Kennecott has, in the past, given considerable effort to exploration; and it is believed to have more than one potential mine site available, with one of undisclosed location selected for the initial operations. This group has employed well-equipped, leased vessels for its exploration efforts.

Kennecott appears to have completed its basic development work on its nodule collector and is now planning its large-scale test at sea in early 1979. The previous efforts involved a test mining unit of approximately 2,000 tpd capacity. It was tested at a 15,000 ft depth, but no nodules were brought to the surface. The planned operations will involve the towing of the dredge head at the end of a near-vertical pipe string from the surface ship. It appears the previous tests made with the dredge head were accomplished by tow

ing with a cable. Evidently this is the technique used by other groups for initial tests.

It appears that Kennecott plans to test a full scale system at sea in the range of 5,000 to 15,000 tpd capacity. For this reason, the tests will be a year or two later than the tests planned by the other groups.

Apparently, the design of both the miner and lift system is fixed. Kennecott has not announced the ship to be used for the tests. However, a system with a production capacity of 5,000 to 15,000 tpd will require a fairly large pipe of up to 20 in. or more. This, in turn, could require a pipe lift system in the range of approximately 4 million Ib. While this is three times the lift capacity of present offshore oil drilling vessels, it is only a fraction of the pipe lift capacity of the Glomar Explorer. The U.S. Navy is now in the process of moth-balling the Glomar Explorer so it is not known if the ship will be available or economically desirable for such large-scale tests. However, it should be stated that such largescale tests could cost as much as $75 to $100 million.

Lockheed

Lockheed is in the process of forming a consortium for the development of a complete ocean mining and processing system. Lockheed's activities in ocean mining have extended over a period of more than 12 years and include the development of mining and processing technology. The activity is under the direction of Conrad G. Welling, the author of these comments.

Lockheed has developed a test miner and has essentially completed the required land tests in a simulated sea floor "mud pit" as well as submerged in a wet tank. The company has not yet selected a ship for the at sea tests, therefore, it will probably be some time in 1978 that these initial tests will be made. Consideration has been given to the Glomar Explorer as well as drilling vessels. It is not known at this time if the Glomar Explorer will be available when required. If not, or for other reasons not optimum for the test, another ship will be used. The test miner has a production capacity of approximately 20 to 25 percent of the planned operational unit. The successful tests of this miner will provide engineering data required for the production miner.

December 1976