United States Patent: 3811730

[US Patent & Trademark Office, Patent Full Text and Image Database]

( 38 of 38 )

United States Patent	3,811,730
Dane, Jr.	May 21, 1974

DEEP SEA MINING SYSTEM

Abstract

A deep sea mining system for mining ore from the surface of an ocean bed using a mining plant that travels the bed, a Sessile ship, and an interconnecting hoist pipe circuit. The system is transported to the mining site by a ship with streamline and structural strengthening sections which are later detached and reassembled into an auxiliary vessel. The hoist pipe circuit is towed to the mining site in sections which, during assembly of the hoist pipe circuit, are used to lower the plant to the ocean bed. After being lowered, the plant covers the bottom, the Sessile ship following the course of the plant, continually hovering over it. A scraper bucket system mounted on arms incorporated by the plant scrape ore nodules from the surface of the bed. The plant cleans the nodules of valueless mud, crushes them to particle size and couples the ore particles to the hoist pipe circuit where they are lifted as slurry and deposited in bins of the hovering Sessile ship.

Inventors:	Dane, Jr.; Ernest Blaney (Belmont, MA)
Appl. No.:	05/284,606
Filed:	August 29, 1972

Current U.S. Class: 299/8 ; 37/308; 37/310; 37/314; 37/324

Current International Class: E02F 7/00 (20060101); E21C 45/00 (20060101); E02F 5/00 (20060101); E02f 007/00 ()

Field of Search: 299/8,9 37/DIG.8,58,72

References Cited [Referenced By]

U.S. Patent Documents


3433531	March 1969	Koot et al.
3522670	August 1970	Flipse et al.
3693272	September 1972	Gariel
24946	August 1859	Miller
3490157	January 1970	Venus

Primary Examiner: Purser; Ernest R.

Parent Case Text

This application is a continuation-in-part of my copending U.S. Pat. application Serial No. 148,853 which is now abandoned and is a continuation-in-part of U.S. Pat. application Ser. No. 754,191 filed Aug. 21, 1958 and subject to a requirement for restriction.

Claims

1. In a deep sea mining plant for collecting and processing ore nodules on the ocean floor for delivery to a pipe circuit for hoisting to the ocean surface, the combination of;

a vehicle adapted to travel said floor with a velocity S.sub.v and including receiving means for receiving collected nodules, an ore cleaner for removing unwanted mud from said nodules, and means for transferring said cleaned nodules to said pipe,

ore gathering apparatus mounted on said vehicle and extending over a substantial distance laterally from said vehicle to span a strip and adapted to collect nodules from said ocean floor along said distance and deliver them to said receiving means of said vehicle, said ore gathering apparatus having propulsion means adapted to travel said floor laterally spaced apart from said vehicle to move said apparatus with said vehicle

2. The mining plant of claim 1 wherein said means for transporting said cleaned nodules to said pipe circuit includes a surge bin for accumulating said cleaned nodules from said cleaner, and said plant further includes first control means operatively associated with said bin adapted to vary the speed S.sub.v of said vehicle so as to maintain the flow of said cleaned nodules into said bin essentially equal to the flow of said

3. The mining plant of claim 2 wherein said first control means comprises a crawler drive motor for driving said vehicle, a weight transducer for measuring the weight of nodules in said bin and generating signals according to said weight, means for producing a weight reference signal according to a specified weight of nodules to be accumulated in said bin, and means for comparing said signals of said weight transducer with said weight reference signal and causing said crawler drive motor to adjust said speed S.sub.v to maintain said weight of said nodules in said bin

4. A mining plant as set forth in claim 2 wherein said first control means is adapted to drive said vehicle at a speed S.sub.V corresponding with

5. A mining plant ss set forth in claim 4 wherein said speed S.sub.v corresponds with keeping said bin approximately half-filled with nodules.

6. The mining plant of claim 4 wherein said ore gathering apparatus includes a track with an axis "c," a series of scraper buckets circulating along the length of said track at a speed S.sub.c with inbound buckets of said vehicle contributing to the support of said track and having open bottoms and an input axis "b" which is skewed forward of said axis "c" in the direction of said vehicle's motion by an angle .phi., and wherein said plant further includes inclined plate means extending from said receiving means to said ocean floor for providing a riding surface for said inbound buckets from said floor to the top of said receiving means whereby said nodules collected by said inbound buckets are slideably supported by said

7. The mining plant of claim 6 wherein said track is extended at an angle .theta. relative to the negative of said velocity vector S.sub.v, and wherein .phi. is substantially according to the relation.

.phi. = .theta. - tan.sup.-.sup.1 S.sub.c sin .theta./S.sub.v + S.sub.c cos

8. The mining plant of claim 4 wherein said ore gathering apparatus comprises a long arm projecting from said vehicle along an axis "c" describing an angle .theta. of substantially 90.degree. relative to the negative of said velocity vector, with the distal end of said arm carried by a tail-sheave tractor, and an endless scraper which scrapes nodules

9. A mining plant as set forth in claim 8 wherein said ore cleaner comprises a hollow inclined cylinder with an elevated end receiving said nodules from said receiving means, means for rotating said cylinder, a helical plate affixed to the internal surface of said cylinder along which said nodules may slide down said incline upon rotation of said cylinder, and means for directing jets of water on said sliding nodules to clean

10. The combination as defined by claim 2

wherein said apparatus comprises a pair of long arms projecting from said vehicle at an angle .theta. of substantially 90.degree. relative to the negative of said velocity vector S.sub.v with the distal end of each arm carried by a tail-sheave tractor, and and endless scraper which scrapes nodules inwardly from said distal ends to said vehicle along said arms,

wherein said vehicle comprises an ore crusher for reducing said cleaned nodules to particle size, and means for mixing said particle-sized nodules with fluid to produce ore slurry, in further combination with

a Sessile ship adapted to hover over said plant, and

a hoist pipe circuit adapted to pump ore slurry along its length, one end of said circuit connected to said ship and a second end connected to said plant and receiving said ore slurry porduced by said plant, said hoist pipe circuit comprising a series of hoist pipe sections each having a plurality of buoyancy tanks to provide a buoyant force amounting to at least half the weight of said pipe section loaded with ore, and a pump

11. The combination as set forth in claim 10 wherein said first control means comprises a crawler drive motor for driving said vehicle, a weight transducer for measuring the weight of said bin and generating signals according to said weight means for producing a speed setting signal S.sub.v ' according to a specified weight of said bin, and means for comparing said signals of said weight transducer with said speed setting signal and cooperating with said crawler drive motor to adjust said speed

12. The combination of claim 2 wherein said vehicle comprises an ore crusher and means for mixing the resulting crushed ore with water to form an ore slurry, in combination with a hoist pipe circuit comprising a plurality of interconnected sections, each section comprising pumping means, electrical connections, and a dump valve to clear the section in

13. The combination of claim 12 having a hovering stable surface ship with ore bins for receiving said ore slurry and further including:

a submerged float joined to said hoist pipe circuit providing it with a subsurface floating support, and

a flexible, supported pipe connected between said ore bins of said ship and said hoist pipe circuit at said float for providing a flexible conduit for

14. The combination of claim 13 wherein said ore bins are located at about the same depth as said submerged float so that said flexible pipe is

15. The combination of claim 14 wherein said hoist pipe circuit is fabricated of buoyant material for reducing the load of said hoist

16. The combination of claim 15 wherein said stable ship is a Sessile ship in a vertical orientation incorporating a stem section with a narrow stem and an assigned water-line crossing said narrow stem, and said ore bins

17. A sea-going rig for harvesting manganese nodules and the like from the floor of the ocean, comprising,

a. a plurality of long, buoyant hoist pipe sections, each comprising, pumping means to raise an ore slurry at a designed efficient rate, electrical connections for carrying electrical power to and through said sections, interconnecting means to permit said sections to be vertically assembled into a long conduit, an emergency dump valve, and means for rafting said sections together for towing on the high seas,

b. a miner comprising (ii) a vehicle adapted to move across the floor of the ocean with a velocity S.sub.v and including receiving means for receiving collected nodules, an ore cleaner for removing unwanted mud from said nodules, and means for mixing said cleaned nodules with sea water for introduction into said conduit as a slurry, and (ii) ore gathering apparatus mounted on said vehicle and extending over a substantial distance laterally from said vehicle to span a strip and adapted to collect nodules from said ocean floor along said distance and deliver them to said receiving means, comprising propulsion means adapted to move said apparatus with said vehicle while so extended thereby to clean said nodules from said strip,

c. a first control means for controlling the amount of water in said slurry responsive to the lowermost of said pumping means in operation,

d. second control means for operating said dump valves,

e. third control means for controlling said velocity to maintain a steady adequate supply of ore from said apparatus to said means for mixing, and

f. a tender adapted to transport said miner from port to its operations area, to carry the equipment required to assemble said miner to the lowermost of said sections while in said operating area, and to lower said miner so attached to the ocean floor, and adapted to hover over said miner as it is in operation gathering and conveying said ore and to provide the

18. The rig as defined by claim 17 wherein said tender is a flip ship adapted to navigate in a horizontal orientation, and to hover in a

19. In the art of recovering ores comprising manganese nodules and the like from the ocean floor wherein the ore is elevated from the bottom of the ocean in a slurry carried by pumps through a very long conduit, said pumps and conduit being designed to deliver ore to the surface at a sufficiently high rate to be commercially economical, the method of harvesting comprising the steps of:

a. carrying the lower end of said conduit along the floor of the ocean along a predetermined initial path at a controlled velocity, while gathering to said lower end nodules laterally across a wide strip bounded by a first edge and a second edge,

b. gathering ore deposits on the ocean's floor to said lower end from a substantial distance laterally and transverse to said path thereby clearing a strip having a first edge and a second edge, at least one of said edges being distinctively marked by said gathering step,

c. cleaning the gathered ore by water jets at said lower end,

d. mixing said ore with water in an amount controlled to achieve constant maximum efficiency of said conduit and pumps in raising said ore to the surface, and

e. controlling the magnitude of said velocity so that the amount of ore gathered at said lower end is sufficient to supply ore for mixing in the required quantity to achieve constant maximum efficiency of said conduit and pumps in raising said ore to the surface,

f. monitoring the ground at an edge of said strip at said distance to detect an edge previously distinctively marked, and

g. controlling the direction of said velocity responsive to the detection

20. The method of claim 19 with the further step of crushing said ore prior to mixing.

Description

This invention relates generally to ocean mining systems and particularly to systems for retrieving loose ore sediment from deep sea floors.

INTRODUCTION

The mineral resources of deep ocean beds though long recognized have yet to be fully exploited. Sufficient quantities of minerals lie loosely in the sediment of deep sea oozes to make their recovery in scale attractive. Of particular interest are manganese nodules that are found in ocean sediments formed under oxidizing conditions, and are especially widespread in the southeast Pacific Ocean. They are shaped like potatoes, mammilated cannon balls, marbles and also assume less identifiable forms. They range in size with diameters of between 0.5 to 25 cm, however, the majority of nodules recovered from deep sea dredging probes have not exceeded 10 cm in diameter. Numerous photographs taken of the ocean floor indicate that they average about 3 cm in diameter (See The Mineral Resources of the Sea, by John L. Mero, Elsevier Publishing Company (1964)).

In addition to manganese, the nodules contain a number of other minerals in adequate quantities, for example, iron, silicon, aluminum, copper and nickel, to make them an attractive source of these as well. Mineral content is regional with comparatively high concentrations of iron in nodules near the western coasts of North and South America and the eastern coast of Asia, while nodules distant from Pacific islands and continental bodies possess relatively high nickel and copper content.

Most deposits are covered by between 2,000 and 6,000 meters of ocean. They are within the range of some deep submersible vehicles and sampling probes but the feasibility of mining them depends on the capability of recovery in scale, at the rate of many tons per day.

PRIOR ART

Most ocean-mining systems of the prior art are directed toward recovery at comparatively shallow depths and at small scale. Drag dredges, for instance, are of limited capacity and involve considerable turn-around times when used at great depths. Lengthly ladder dredges tend to become massive. When extended from the side of conventional ships wave-induced oscillations of the ship may rupture the interface with the ladder or embed it in the ocean floor. Suction dredges have also been employed. Often in these, however, much power is expended in raising valueless mud. Moreover, systems such as these and others that are stationary may recover insufficient quantities of ore to make them economically unfeasible. In particular U.S. Pat. No. 3,522,670 granted Aug. 4, 1970 to J. E. Flipse et al. discloses apparatus for harvesting nodules with a gathering means which is arranged to crawl around the bottom under control of T.V. cameras and the like, but the gathering of nodules at any instant must be from the immediate locality of the expensive and complex gathering means. U.S. Pat. No. 3,433,531 to Koot recognizes the need to harvest from a substantial area around the lifting apparatus, and the desirability of crushing and treating the gathered material befor lifting it, but does not provide these features with the means hereindisclosed to move the plant rapidly, systematically, and in operating condition from place to place over the ocean floor, so that economic tonnages can be handled in regions where the nodules are of only moderate concentration.

SUMMARY OF INVENTION

In view of the cited limitations in the art of ocean mining, applicant has as the primary object of his invention to provide a system for gathering loosely embedded minerals form deep ocean beds in quantity.

It is another object of his invention to provide an efficient system for mining minerals from deep ocean floors.

It is a further object of his invention to provide a system for mining at ocean depths of 100 fathoms or more.

These and other objects are met by a system comprising a tractored central mining plant and a "Sessile" ship interconnected by a string of buoyant hoist-pipe sections. Except for the pipe sections which are carried in tow, the system is transported to the mining site in the Sessile ship. To reduce drag and provide structural strengthening, the ship is equipped with streamlining, strengthening and propulsion sections that are detatchable at sea and may be reassembled into an auxiliary vessel. Upon reaching the mining site, the sections are separated and the Sessile ship is erected. The mining plant is lowered by linking it up with the first and succeeding pipe sections one at a time. The hoist pipe circuit so formed is completed when the miner reaches the bottom and rests on the ocean floor.

The miner incorporates a tractored vehicle with a pair of arms projecting from its sides. Each arm carries a series of scraper buckets that ride on an endless chain that circulates along the length of the arm. As the vehicle travels the bottom linked with the hovering Sessile ship by the hoist pipe circuit, the circulating buckets scrape nodules on either side of the vehicle cutting a wide swath in the deposit. Gathered nodules are cleaned of valueless mud and crushed into particle size by apparatus on the vehicle. They enter the hoist pipe circuit as slurry and are pumped to temporary storage bins in the ship to await subsequent transfer to an ore freighter.

Because the system is capable of sweeping large areas, it recovers ore at a high rate. The system is efficient as the ore is cleaned of mud prior to transport thereby reducing power consumption. Operation is continuous and involves no turn-around time except for initial deployment and final recovery of the miner which may be some weeks apart. The system is self-contained, all necessary power, equipment, and facilities being supplied by the Sessile ship. These and other features of the system will become apparent from the following detailed description; but this description should not be taken as a representation that the whole system or any parts of it have been actually constructed or actually observed and tested by me to operate in the manner described. This specification is to be read in conjunction with the drawings of the above-mentioned application Serial 148,853 about to be abandoned which are to be transferred and made a part of this application to the extent that they may be of which:

DRAWINGS

FIG. 1 is a sistant bird's eye view of the system in transport to the mining site.

FIG. 2 is a side cut-away view of the freed Sessile ship of FIG. 1 in a vertical orientation.

FIG. 2A illustrates the bottom dump hatches of the ore bins in the ship.

FIG. 3 is a partial cross-sectional side view of two joined pipe sections of FIG. 1 illustrating the principal features of a typical pipe.

FIGS. 3A, 3B, and 3C are top cross-sectional views of the pipe of FIG. 3 along cutting planes A--A, B--B, and C--C, respectively, while FIG. 3D is a cross-sectional view of the spherical tanks used in the lower pipe sections.

FIGS. 4 and 4A are side and vertical views, respectively, of the dump valve in the pipe section of FIG. 3.

FIG. 5 is a detailed side view of the secured junction of FIG. 3.

FIG. 6 is a side view of the Manbot used to construct the hoist pipe circuit and its operation in securing the pipe junction of FIGS. 3 and 5.

FIG. 7 illustrates the haul-down of pipe sections of FIG. 1 in the construction of the hoist pipe circuit.

FIG. 8 illustrates the terminal junction between the hoist pipe circuit and the Sessile ship of FIG. 3.

FIG. 9 is a front view of the folded arms of the miner of FIG. 8.

FIG. 10 is a side view of the double-joint fold of the arms of FIG. 9.

FIG. 11 is a distant vertical view of the miner of FIG. 2 with arms extended.

FIGS. 12 and 12A are side and front views, respectively, of the ore-gathering buckets mounted on the miner's arms.

FIGS. 13 and 14 are side views of the near and far ends, respectively, of the miner's arms.

FIG. 15 is a side view of the tractored vehicle of the miner.

FIG. 16 is a cut-away view of the ore cleaner in the vehicle of FIG. 15.

FIG. 17 is a diagram of a speed-control system for the tail-sheave tractor of FIG. 14.

FIG. 18 illustrates a steering control system for the tail sheave tractor of FIG. 14.

FIG. 19 is a functional block diagram of a system for controlling the advance rate of the tractored vehicle of FIG. 15.

FIG. 20 illustrates a geared-motor drive for use in deep sea apparatus.

PREFERRED EMBODIMENT

The surface components of the mining system are provided by a tender that performs a mumber of functions to sustain the venture, including the following;

a. transports the miner to a distant mining site,

b. supplies power to the miner and hoist pipe circuit,

c. provides a control facility for all apparatus in the system,

d. stores ore mined from the ocean bed temporarily pending transfer to another ship,

e. provides living accommodations for the crew and holds enough commissaries and fuel for at least a month's work,

f. provides a sufficiently stable and suitable base for lowering the miner and construction of the lengthly hoist pipe circuit therewith, for retrieving them upon conclusion of operations, and for receiving ore as it hovers over the miner working the ocean floor.

While conventional ships are adequate in some of the above respects, they may be troublesome with regard to the provision of a stable base in rough seas. During construction, the miner is lowered from the ship attached to the hoist pipe circuit as the latter is assembled from the floating pipe sections. The accumulating load may develop a mass of over 1,000 tons before the miner reaches the bottom. A large component of the static load is compensated by buoyancy tanks built into the respective pipe sections. However, the dynamic load produced by the massive ship as it rolls, pitches and heaves in the waves, some of which are in the order of 20 feet or more in height, is imposed fully on the construction hoists and the uppermost sections of the pipe circuit. Such dynamic loads could damage the pipe circuit or cause it to break away from the ship altogether.

The sensitivity of the hoist circuit to unwanted motion characteristic of conventional ships may be reduced by using complex compensating equipment in the pipe circuit. Alternatively, the surface terminal may be supplied by a semi-submerged catamaran, like those used on oil-drilling sea rigs. However, the preferred embodiment of the present system features a simpler and less expensive approach by incorporating a surface ship whose ratio of displacement change to total displacement as a function of depth from an assigned water-line is small compared to that of a conventional ship. Such features are realized in a "Sessile" or "Flip" type ship illustrated in later FIG. 2 which has a relatively thin stem section and an assigned water-line midway up the stem. The section comprises a relatively narrow cylindrical steel shell bounded by two widening conical shells, with a slope of about 45.degree.. The upper conical shell merges into a cylindrically shaped double decked top while the lower conical shell is bounded by a long and wide cylindrical shell that is submerged when the ship is erected along the vertical. The cross-sectional area of the bottom cylinder is much greater than that of the stem section which is at the ocean surface. Consequently, changes in displacement due to wave action is significantly less than that of a conventional ship. Moreover, the massive ship's submerged bottom provides substantial damping to motion, particularly heave, caused by waves.

The Sessile ship has a draft of about 85 meters, which makes her too deep to float in many harbors. Therefore, she is conveyed from port to deeper water in a horizontal orientation. Because of the flatness of her top deck, she develops considerable drag or resistance to passage in the sea. Her velocity is accordingly limited to a few knots in this orientation. With the aid of special power drives adapted to propel the ship at inclined attitudes, say with her top deck a few feet or so above the surface, the ship with miner attached may be transported to a mining site at restricted speeds. As surface conditions change from calm to rough, the inclination of the ship may be varied by internal ballasting so the top deck clears the waves. However, due to the slow speeds of such self-propelling modes, mining sites attempted are limited to short distances from port.

Since many of the productive mining areas may be some thousands of kilometers from port, it is desirable to provide for more expeditious transport to the distant sites. Accordingly, the Sessile ship is supplied with special sections that reduce her resistance to motion, provide propulsion, and add structural strengthening to her weak stem section. A Sessile ship so adapted is shown in the distant vertical view of FIG. 1, and more fully described in applicant's copending application "Ship Sections Adapted for Disassembly and Reassembly at Sea," U.S. Pat. Ser. No. 97,484 also subject to the above requirement for restriction. As illustrated in FIG. 1, Sessile ship 100, with miner 300 clamped through an opening in ship bottom 180, has her top deck covered by streamlining bow section 20, her stem section strengthened by midships section 40, and is propelled by powered stern section 60. Upon reaching the mining site, the sections are detatched in the manner described in the above referenced copending application. The ship is then erected along the vertical by controlled flooding of its internal ballast tanks, eventually assuming the vertical orientation shown in FIG. 2.

Referring now to FIG. 2, the Sessile ship contains multiple levels of decks 125a through 125g, and bottom ore bins 175. Decks 125a through 125c have single and double drum winches 127; 129; 131; 133; 137; respectively. The winches hold cables 127, 129, 131, 133, and 137 extending down central well 121 or out hatchway 143 and through a series of snatch blocks 147, some of the latter resting on flat landing 149. Cable 127 is a sheet cable of light-weight electrical conductors for carrying power and control signals from a control room on deck 125e to miner 300 and pipes 200. Appropriate lines of cable 127 are connected to the various terminals of miner 300 and pipes 200 during construction of the hoist circuit. Cable 131 has a pair of electrical wires that convey temporary power for initially operating the two top winches of the first pipe section. Cable 129 is an elevator cable for manipulating the position of a manned submersible as will be described. Cables 133 and 137 are hoist cables each having two lines with a load capacity greater than the weight of miner 300, which may be in the order of 100 tons. Two lines of cable 133 are attached to eyelets at the top of outlet pipe 305 of miner 300, and each pays-out from one of the interconnected drums of winch 133'. A line of cable 137 from coupled drums 137' is attached to each of folding joints 346 of the miners arms. Hoist cables 133 and 137 serve to lower the miner and forming hoist circuit.

Decks 125d contain personnel facilities and space for a number of functions in support of mining operations. Fuel cells 125f' on deck 125f supply electrical power to the system and to drive propellers 181 to station the ship. Ballast tanks 155b on deck 125g cooperate with blow tanks 155a to perform ballasting action. Circular pipe 165 is designed to receive mined ore from the mining plant 300 after it starts mining the ocean floor. Ore slurry from pipe 165 is released into funnel shaped bins 175. As shown in FIG. 2A, a typical bin is equipped with dump hatches 177 (shown open) and pumping apparatus 187 and 189 between feedline 183 and external discharge pipe 190. Affixed to bottom 180 is powered stern section 60. All equipment for the mining operation is stored on board except for buoyant hoist pipes 200 that are towed as a raft by sea-going tug 85. As discussed in detail in the above referenced parent application, ship sections 20, 40 and 60 are specially adapted to detach at sea and recombine into an auxiliary vessel for further utilization.

Once over the intended mining site, the special sections are detached and the Sessile ship is raised along the vertical by controlled flooding of its ballast tanks. The erected ship appears in the cut-away side view of FIG. 2 with pipe sections 200 stationed nearby tended by motored launch 10. Details of the ship are next outlined.

SUGGESTED DIMENSIONS FOR THE SHIP

The following general dimensions are recommended for the ship.

Vertical Heights or Lengths

Upper to lower decks of the Top: 2.5 meters

Lower deck to cylindrical shell in stem section: 9 meters

Cylindrical shell in stem section: 16 meters

Vertical length of lower conic in stem section: 9 meters

Bottom: 42 meters

Radii

Top radius (r): 12.5 meters

Radius (s') of top cylindrical shell in stem section: 10 meters

Radius (s) of central cylindrical shell of stem section: 3.5 meters

Radius of bottom: 12.5 meters

HOIST PIPE CIRCUIT

The hoist pipe circuit used to transfer ore from central miner 300 to Sessile ship 100 is constructed from the several hoist pipe sections 200 of FIGS. 1 and 2 towed to the mining site. The pipes are serially connected between the miner and pipe 165 of ore bins 175. Each pipe section includes a pump for raising the slurry through its length and an emergency valve to permit rapid dumping of the slurry in the event that there is a serious failure in the system. The pipes are made of strong buoyant material and further equipped with buouancy tanks. They are designed so that the resulting buouancy is sufficient to support most of the total weight of the loaded pipe sections including that of its pump, pipe and about 8 tons of ore slurry. The pipes have sufficient radial strength to withstand the internal pressure of the slurry. They are also provided with enough longitudinal reinforcement to withstand both the stresses caused by subsurface sea forces and to support the weight of the mining plant. The pipes are used to transport the plant between the Sessile ship and sea bottom both during the initial deployment of the system and upon termination of the mining operation. The pipes are also equipped with water-tight electrical connectors that receive lines of cable system 127 supplying electrical power for the pumps and auxiliary equipment. One pair of power lines is assigned to each pipe and the performance of the corresponding pump is monitored by measuring the power it consumes.

PIPE SECTIONS

The principal features of each pipe section 200 are illustrated in FIGS. 3-6. FIG. 3 shows two pipe sections 200' and 200" as they appear after being joined in the construction of the hoist pipe circuit. The top of pipe section 200' is joined to a succeeding pipe 200" by toggle ring binder 205 and other fastenings to be later described in conjunction with FIG. 5. Pipe section 200" is representative of the lower portion of each pipe section. It comprises plastic pipe 201 having an internal diameter of about 40 cm. except near pump section 220 where it widens out to a diameter of 3 to 4 meters. Located above pump section 220 is about 100 meters in length of floatation gear in the form of hollow tanks 240. Above the tanks each pipe 200 assumes the form of a simple pipe 200'.

Since it is difficult to extrude pipes in 300 meter sections, each pipe section is fabricated on shore in parts that are joined lengthwise by molding or otherwise. Pipe 201 is made of strong, non-porous buoyant material having a compressibility approximating or preferably less than that of water. These properties are aimed at preventing the pipes from sinking gradually when exposed to the sea pressures along the length of the pipe circuit over considerable periods of time. Polypropylene and polyethylene plastics possess the sought characteristics. Pipe walls are about 2.5cm. thick and are internally lined with materials 202 that resists the abrasion of moving slurry, for example, are lined with about 0.5 cm. of rubber. Each pipe is equipped with four or more I-bars 203 that improve the natural tensile strength of the pipe. The I-bars are of plastic potted fiberglass and secured to the pipe with the aid of wrapping straps disposed around each pipe. The rubber lining and I-bars are shown in FIGS. 3A, 3B, and 3C which are cross-sectional views of the areas cut by planes A--A, B--B and C--C, respectively.

Pump section 220 houses a pump with motor 224 within casing 225 capable of pumping 500 metric tons of slurry per hour at a moderate head. Motor 224 is coupled downward to rotor 227 having many vanes located at the bottom of pump section 220. A modified version of the radial flow type used on hydraulic dredges is employed in the pump. The modification resides in building an upward curvature in the stator's guide vanes.

Specifically, in a conventional rotary pump, the rotor vanes impart tangential motion on the fluid. The fluid is collected by a stator surrounding the rotor and is redirected out the pump's discharge terminal. However, in the modified pump shown in FIGS. 3 and 3B, stator guide vanes 226 are mounted on the inside wall of pump section 220. The surfaces at the input side of guide vanes 226 are shaped to receive the tangential flow while the surfaces at the output side are co-directional with the axis of the rotor or that of the pipe. The intervening surfaces of the vanes have a gradual twist that provide a smooth directional transition. Stator vanes 226 thus transform ore slurry leaving rotor vanes 227 from a tangential flow into an axial flow upward through the spacing between casing 225 and the internal wall of pump section 220. To reduce wear in this area, the rotor and stator vanes and casing 225 are rubber lined.

To avoid brush wear, pump motors are three phase a-c motors. Cable system 127, shown in FIGS. 3A, 3B and 3C is a sheet cable which is added to the pipe section. The individual lines of cable 127 tap-off the sheet at points along its length and carry two phases of the three phase supply. Two such tap-off lines 229 are illustrated in the area of the dump valve of FIG. 4A to which reference is shortly made. Plate 231 mounted on the pump section provides the third terminal of the supply. It has enough area to provide a good electrical circuit through seawater between the pipe and the ship's structure that supplies the other ground terminal. For maximum efficiency, rotor vanes 227 are run at about 960 rpm. For operating minimum weight motors at maximum efficiency, high speeds of about 1,700 rpm are advisable. To gain this advantage, the coupling between rotor vanes 227 and the pump motor may have a single-step reduction gear (not shown) to reduce speed.

Still referring to FIG. 3, just above pump section 220 is about 100 meters of serially arranged tanks 240 affixed to the outside of pipe 201. These supply about three-fourths of the buoyancy for a section filled with ore slurry. Tanks used at greater depth, say below 3,000 meters, require greater strength than ones used at lesser depths. Upper seas tanks are cylindrical with hemispherical tops and bottoms as in FIGS. 3 and 3A, and are made of fiberglass, plastic or aluminum. Lower seas tanks 240' of FIG. 3D, are preferably spherical and made of more expensive hollow glass. Tanks 240 and 240' are filled with air or another gas. The tanks are covered by a thick plastic cover or tube 239 that makes them easier to tow on the surface and protects them from abrasion during construction of the pipe circuit to be described subsequently. The tank floatation gear is further secured to pipes 201 by bands that extend around both tanks and pipes.

The tanks are serially disposed along the length of a pipe with collar-like cushions 237 interposed between the opposing curved surfaces of adjacent tanks. Cushions 237 are of solid propylene reinforced with fiberglass and are designed to prevent high direct contact pressures from occuring between the curved surfaces of the tanks. As is seen in FIGS. 3 and 3D, a pair of cables is linked between each of padded collars 237 and the heavy pump section 220 to distribute the load between tanks, preferably so that they each support about the same weight.

Near the bottom of pump section 220 is emergency dump valve 250. Valve 250 provides an exit by-passing the pump's rotor and stator for releasing the column of ore slurry in the event of an emergency and also affords for repairing the pump in the event it is necessary. Valve 250 is positioned to allow the pipe to release most if not all of its slurry without backing-up in the pump. FIG. 4 offers a cut-away side view with details of valves 250 shown in a closed condition, while FIG. 4A is a top view of the valve when opened. Referring to FIG. 4, dump valve 250 comprises door 241 mounted on hinge 242. Door 241 is closed by the pull of chain 243 when winch 245 is energized. When door 241 is shut, solenoid catch 247 is activated causing it to force up against the door, locking it in place. Winch 245 is then reversed allowing slack in chain 243, this state being shown in FIG. 4. Commands for operating the mechanisms are provided by lines 229 of cable system 127 coupled into pump section 220 by connectors 229'. Lines 229 carry power to both the pump motor and solenoid catch 247. In the event the pump is shut down due to a power failure or intentionally because of a malfunction, catch 247 is automatically released. Door 241 swings open by the force of the slurry to the position of FIG. 4A and the ore is dumped. Lines 229 also include a line for controlling winch 245 so that it takes up or releases chain 243 when desired.

FIGS. 4 and 4A also illustrate other features of the area near pump section 220. Rubber lining 202 is shown covering the internal wall of pipe 201 and casing 225 of the pump motor. One of the series of straps 249 wraps around longitudinally extending strengthening I-bars 203 and pipe 201 holding the former in place. One of the series of binding cable 251 holds those lines of cable system 127 continuing down to a lower pipe section. Top view 4A shows stator guide vanes 226 fixed to the inside wall of the pump section.

Connectors, such as connector 229', employed to connect cable system 127 to various points in the mining system are oil filled and of the kind typically used to couple power into submarines or other submersibles. They point downward and have an oil-filled chamber that protects the internal sockets from the sea water. A tape seal across the mouth of the chamber helps to retain oil and exclude the sea water. To resist corrosion, cable pins and connector sockets are made of solid copper or are copper plated. Once an electrical connection is made, it is sealed by rubber tape or other suitable material and secured by a strong spring fixture to prevent it from being shaken free by pump or other vibrations.

FIG. 5 is a detailed view of the junction of pipe section 200' and 200" of FIG. 3. To stablize their registration the ends of each pipe section are flanged. Strengthening I-bars terminate into eye splices 204 at both ends of a pipe which have extra holes 204a for receiving hoisting or haul-down cables. The bottom of each pipe section is equipped with pelican hooks 207 having a safety ring 207a, ring binder 205 held by chain 205a, while the eye splice at the top of each pipe is provided with shackle 207e.

The pipes are joined by aligning their ends so that the flanges are in smooth registration and both sets of eye splices 204 are aligned, with mechanical operations worked by the "Manbot" of later FIG. 6. Ringbinder 205 is fitted crosswise over the joint. Toggle levers 205b are used to clamp the ring in place and pelican hooks 207 are then secured. Hook 207 has ring 207a and member 207b joined at one to rotatable arm 207d by pin 207c. The opposite end of member 207b has jaws bolted to short turnbuckle 209. Each arm 207d is arranged to fit through shackle 207e fixed to an eye splice at the top of a lower pipe 200' and to fold back on member 207b. Turnbuckle 209 is is located below the end of I-bar 203. Once a pelican hook is fitted through its shackle 207e and folded over member 207b and locked by ring 207a, the clamping action is firmed by adjustment of turnbuckle 209.

Each of the pipe section is as just described except the first one that has one or a pair of winches near its top that help support folded joints 346 of the miner's arms. The winch is illustrated in FIG. 6 where the pipe sections are assumed to be the first and second. The winch has drum 339 holding cables 341 and 341' linked with joints 346 and 346' of the arms. The drum is operated by motor 335 initially energized by cable 131 and finally by sheet cable 127.

THE MANBOT ASSEMBLER

Construction operations occur in quiet water with the aid of one or more manned submersible machines, here termed a "Manbot," which is a variant of the kind described in "The Deep Submersible," by Richard D. Terry, published by Weston Periodicals Co. (1966), at page 169. It consists of a water-tight chamber capable of providing a shirt-sleeve environment to an operator at depths of at least 400 meters. The Manbot is shown in FIG. 6 making a junction between the first and second pipe sections. It has chamber 250 linked by suspension member 251 to the ship's elevator cable 129. It has a telephone to the ship's control room and is ventilated by hoses 252 and 254. Power is furnished through cable 255. Anchoring clasps 262 are provided to secure it along positions on the pipe. Saddles 261 on the inside of clasps 262 fit the sides of a pipe. Clasps 262 are opened and closed by cylinders 264. A similar member, upper clasp 272, extends upward through support 268 and is operated by cylinder 271. Angular adjustment cylinder 267 connected to support 268 controls the angular position of clasp 272, while support 268 manipulates its height. One or more cylinder-operated manipulator arms 275 are included to perform manual functions. In FIG. 6 one is shown closing a pelican hook at the bottom of pipe 200". Tool crib 273 installed in the clasp is within easy reach of arms 275. At the bottom of chamber 250 is a pair of interconnected drums 280' each containing over 400 meters of haul-down cable 280 with enough strength to haul 10 tons of load. These are used to haul-down pipe sections 200 during construction of the hoist pipe circuit.

LOWERING THE MINER AND PIPE SECTIONS, PROCEDURE

Referring now back to FIG. 2, hoist cables 133 and 137 are connected to miner 300 when the system is prepared for deployment. Pipe sections 200 and motored launch 10 are brought in the proximity of the ship, and an endless wire 157 with an attached hook ring is run down central well 121, to the launch and back to the ship through an opening made by the removal of plate 143. Lowering of the miner 300 begins by releasing its clamps with ship 100 so that it is supported entirely by cables 133 and 137. Winches 133' and 137' then pay-out cable at the same rate so miner 300 descends levelly until it reaches a depth of a little more than one pipe length, say about 400 meters. The Manbot, which is linked with cable 129, may clamp itself to outlet pipe 305 or be lowered after the miner reaches its station. Before descending, haul-down cables 280 are hooked to the ring on endless wire 157 so that the Manbot may release cable upon its descent. When the Manbot is firmly clamped to outlet pipe 305, it so informs the ship and the first pipe section is prepared for lowering. Personnel in launch 10 draw on endless wire 157 holdng the ends of cables 280 and connect them up with the bottom of the first pipe section.

With the assistance of personnel in the launch, the first pipe section is hauled-down until it is about 5 cm. above the top of the miner's outlet pipe 305. Using upper clasp 272, the Manbot draws the two pipes into alignment and firms the junction as was discussed earlier. Elevated by cable 129, the Manbot again links cable 280 to the endless wire and then returns to the top of the first pipe section. Temporary electrical cable 131 is drawn down and connected to the winches of the first pipe section. Cables 341 and 341' of the winches are connected to joints 346 and 346'. They assume the load of lines 137 which are returned to the ship and led down its side through snatch block 147 along the course of dashed line 137 of FIG. 2. Cable 280 is then used to haul down cables 137 whereupon they are connected to the top of the first pipe section. With cables 137 assuming the load along the outboard side of ship 100, cables 133 are released. Simultaneously, ballast tanks 155b on the opposite side of the ship take in enough water to counter the off-center load. Cables 133 are retrieved and led outboard of the ship along dashed line 133 of FIG. 2. Next, elevator cable 129 and the Manbot are drawn up and led over the side of the ship along dashed line 129 of FIG. 2 as is electrical sheet cable 127. The latter is linked to the endless wire whereupon it is received by the Manbot that connects it up with all electrical apparatus including the pump and winches of the first pipe section, and control and monitoring equipment in the tractored vehicle and the tail sheave tractors.

The Manbot ascends, connects its cables 280 to the endless wire and returns to the top of the first hoist pipe. Cables 280 are connected to the bottom of the second pipe section. Lines 137 are lowered one pipe length, the Manbot paying-out cable 280 as it rides down with the pipe. The second pipe section is subsequently hauled-down, which operation is illustrated in FIG. 7, but not to scale, and where sheet cable 127 is omitted for clarity. The second pipe section is aligned and registered with the first. After making electrical connections between lines of cable 127 and electrical terminals in the second pipe, the Manbot is raised by elevator cable 129 toward the endless wire to which it attaches haul-down cable 280. Previously freed hoist cable 133 is linked with cable 280 near the ocean surface. Releasing cable 280, the Manbot then descends to the top of the second pipe where it anchors itself, and then draws cable 133 down with winch 280' and connects it up with eye splices at the top of the pipe.

The Manbot is next lowered by elevator cable 129 to the top of the first pipe section. Upon instructions from the Manbot the load is gradually shifted from cable 137 to cable 133. The Manbot frees cable 137 and returns toward the surface to connect haul-down cable 280 to the endless wire. After the Manbot returns to a station on the top of the second pipe section, winch 133' lowers the miner to a third depth, the Manbot riding down to the construction depth. Cable 280 is then attached to the bottom of the third pipe section and it is prepared for transport to the forming pipe circuit.

The above sequence of operations performed by the Manbot is repeated until the miner reaches the bottom. Hoist cables 137 are used to secure the top of odd-numbered pipe sections and assume the suspended load when even-numbered sections are hauled-down by the Manbot with cable 280 and linked therewith. Similarly, hoist cables 133 are utilized to hold the load at the tops of even-numbered pipe sections when odd-numbered ones are hauled-down. More generally, miner 300 is lowered to the kth depth, where k is an integer (k= 1, 2, . . . n), and the kth pipe section is hauled-down by the Manbot clamped to the top of the (k-1)th pipe section. After the junction is secured, sheet cable 127 is connected to electrical apparatus in the pipe. The Manbot is then raised by cable 129 to attach its haul-down cable 280 to endless wire 157 for transfer to the free hoist cable of cables 133 and 137. The free cable is then drawn down and linked with the kth pipe section and assumes the suspended load. The alternative hoist cable is freed and the Manbot elevated to attach cable 280 to the endless wire for transfer to the (k+1)th pipe. The Manbot then stations itself on the top of the kth pipe section whereupon the miner is lowered to the (k+1)th depth, the Manbot rinding down to the construction depth in preparation for the lowering of the (k+1)th pipe section.

During formation of the hoist pipe circuit, the remaining distance to bottom is estimated by comparing the known length of the circuit with the depth indicated on the ship's fathometer. Scanning sonars on tail sheave tractors 356 offer a more precise indication of the distance to bottom. When the miner reaches the ocean floor, the load on cables 133 or 137 holding the last pipe section lightens abruptly.

Once the miner is solidly on the bottom, the nth pipe section is hauled-down and joined the the (n-1)th section. The nth section may be shorter than the others in order to locate the upper end of the hoist circuit within a short distance of the surface, say 50 to 100 meters depth. Next, a large float containing a special power and control line with the ship, buoyancy tanks, two or three winched lines, one end of a flexible pipe and other equipment is guided to a point over the nth pipe. The lines are connected-up with the Manbot's haul-down cables. The Manbot is then stated on the top of the nth pipe section. It draws the lines down and links them up with auxiliary eye-splices at the top of the nth pipe section. The winches are next activated and reel-up the lines connected to the nth pipe as the float is drawn toward the top of the pipe. The Manbot guides the float into alignment so that the pipe threads a central aperture in the float and then secures it with pelican hooks and suitable fastenings.

Referring now to FIG. 8, after float 290 is secured, one end of flexible pipe 295 temporarily fastened to the float is engaged with the top of the nth pipe. The other end of pipe 295 is already joined to distribution pipe 165 over the ore bins in the ship. Flexible pipe 295 is supported by a cable connected to the ship, and sheet cable 127 is fastened to pipe 295.

Ballast tanks in the float are pumped out to offer a buoyancy slightly more than the uncompensated weight of the hoist circuit. It is recalled that buoyancy tanks in the pipes provide an upward force of about three-fourths the weight of each pipe loaded with ore. For example, assuming each pipe section has a capacity of 8 tons of ore, a section is 5 tons "light" when empty and 3 tons "heavy" when filled. For neutral buoyancy in a circuit of 17 sections, float 290 provides a vertical force of 51 tons.

Float 290 is linked with small surface buoy 294 containing radio tracking equipment and flashing lights. The buoy is small enough to offer little drag to the pipe circuit even in a typhoon. In the event of a serious storm, the ship is detached from the circuit and driven to a safe location. Buoy 294 provides a reference to the returning ship. Float 290 is located deep enough below the surface to be unaffected by storms.

EXTENDING THE ARMS

The arms are unfolded one at a time by the coordination of winches 339 of the first pipe section of FIG. 6 and maneuvers performed by each tail sheave tractor 356. Tractors 356 are initially secured to vehicle 301 by electrically actuated davits 311 of latter FIG. 15 and other remotely controlled catches transmitted from the ship through cable 127. Tractors 356 are slightly elevated by a few centimeters, and are lowered to the floor prior to their release. Running gear within the tractors is tripped by relays to afford direct or manual control from the ship. Scanning sonars, lights and the closed circuit t.v. system are turned on. Upon receipt of a manual control command from the ship, tail sheave tractors 356 turn sharply outward and travel away from vehicle 301. A t.v. camera is directed to scan astern of tractors 356 to assure that their course is approximately at right angles to the heading direction of vehicle 301. As the tractors move outward, winches 339 of the first pipe are activated and pay-out cable. Angle transducers 349 at joints 346 indicate the angular disposition of the folds. The outputs of transducers are monitored shipboard and signify appropriate signals to be transmitted to speed control equipment in tractors 356. When transducers 349 indicate the joints to be substantially opened, say at about 160.degree., the outbound tractors 356 are slowed-down progressively until they are just crawling, for instance at a speed of 10 cm/min., when the arms are completely outstretched.

CENTRAL ORE MINER

Ore is gathered from the bottom surface by central ore mining plant 300. The plant incorporates a tractored vehicle with a pair of foldable arms at its port and starboard sides, each being coupled to the vehicle by a rotatable mast. The opposite end of each arm is supported by a tail sheave tractor that is driven parallel to the vehicle. The arms carry a circulating endless chain with attached buckets or hoes that scrape nodules along successive paths and deliver them to the vehicle as it proceeds along the bottom. The nodules are dumped into a trough mounted on the front of the vehicle. A pair of slanting plates shaped like a snow plow is mounted on the front of the vehicle. These force ore sediment to either side where it is gathered up by the incoming buckets. The The plant thus clears a strip which is spanned by the vehicle and its two extended arms.

The sediment delivered by the buckets is transferred from the trough to a washing cylinder where the mud is separated from the nodules. The process of removing valueless mud saves the large amount of valuable energy and plant capacity that would otherwise be required to lift it through the hoist pipe circuit. The cleaned nodules are then fed into a crusher where they are reduced to particles of about 1 cm maximum diameter. The particles are transferred to a surge bin coupled to the suction feed of the first hoist pipe where they enter as slurry. The slurry is pumped up through the hoist pipe circuit and to circular pipe 165 of hovering Sessile ship 100 into ore bins 175. The gathering, processing and transfer of ore to the surface ship in this manner is continuous as the plant sweeps the bottom.

The operation of the ore cleaner and the scraper buckets in many situations stirs up the mud so that visual observations may be impossible, however, hulks of sunken ships are widespread, and there may be other hazards to avoid, accordingly television camera 359, sonar systems 360 and high-intensity lights 358 are provided at the front of the sheave tractors 356, where visibility may be best. Power for this electrical apparatus is supplied by lines of cable system 127 that runs down the pipe string and out along each of the arms. Information signals return to the control system in the control room 125e of the ship through the same cable system.

As the miner operates, the edge of the strip that has been mined will be distinctively marked by the tracks of the tail sheave tractor 356 and by the bites of the scraper buckets. Both of these marks are periodic in nature. This periodicity is unnatural and will distinguish sonar echoes from these periodic artifacts from echoes from naturally occurring features of the bottom. It follows, therefore that the sonar system 360 may be provided with a mode of operation wherein it may seek out and follow these distinctive markings even though individual bucket and track marks may be indistinct.

By causing one of the tail-sheave tractors to follow the edge of a previously mined strip, the means of efficient and accurate control of the collection is at hand. The miner may be lowered to the top of a hill, and follow a spiral path around it. After one turn under direct control, the uphill tractor's sonar acquires and follows the track made by the down-hill tractor on the previous circuit. Thereafter the equipment will systematically mine a circular area of steadily increasing diameter.

For flat areas, the tractor may follow a compass heading until the deposits become too lean, then double back along the track, until the whole area is mined in parallel strips, the tracking preventing the overlapping of the mining strips.

Since the ship is physically linked to the plant by a fixed length of hoist piping, there must be minimum lateral motion of the ship relative to the plant. Personnel in control room 125e maneuver the ship to hover continually over the plant. Motion is made very slow to avoid high drag forces on the extensive length of pipe. In addition to drag, other factors limit the advance rate. First is the amount of power required to drive a vehicle at such great depths. Secondly, an excessive speed tends to develop a catenary in the pipe and poses the need for additional piping. To maintain drive power within reasonable limits and to avoid unnecessary complications in the hoist circuit, the maximum advance rate of the plant is limited to 0.5 m/sec. Within this limit, the average speed of the vehicle is servo controlled to deliver a constant flow of about 500 tons of ore per hour.

The speed of the vehicle is modified by monitoring the weight of ore particles in the surge bin. The hoist pipe circuit is withdrawing slurry at its capacity of about 500 tons per hour. If the bin does not receive enough ore to support this rate, the total weight of the bin varies. A decrease in total weight indicates that the vehicle should be speeded-up, whereas an increase in weight indicates that it should be slowed-down. A weight transducer monitors the weight of the bin and generates an electrical signal the amplitude of which is modulated by the weight. This signal is used to control the advance rate of the vehicle.

These and other features of the plant are illustrated in FIGS. 9 and through 19 and related auxiliary views. FIG. 9 is a front view of the plant emphasizing port and starboard arms 340 and 340' prior to their extension. The arms are maintained in this folded condition by tension in lines 341 and 341' between joints 346 and 346' and winches at the top of the first pipe section. Both arms are of the same construction. Consequently, further reference is made to the port-side arm in unprimed notation.

Again referring to FIG. 9, arm 340 comprises a double-tiered track 342 carrying sprocketed chain 350 that circulates between drive sprocket 344 and tail sheave 345. Attached to chain 350 are a series of buckets 351 preferably skewed to reduce crabbing. Tail sheave 345 is connected to tail sheave tractor 356 by swiveling support frame 357, while drive sprocket 344 is mounted on rotatable mast 313 above ore receiving trough 308.

FIG. 10 shows details of the double-hinged joint 346 of the track. Hinges 347 are set inboard of the rails with their axes just below the head of the inverted rail. Hook 348 is remotely controlled to connect-up with the lower branch of chain 350 and release it when the chain becomes operative. Once the arms are unfolded, outbound buckets of upper track 342b are inverted while inbound buckets on lower track 342a are righted and contact the bed.

FIG. 11 shows vehicle 301 with extended arms scraping a strip bounding edge 380 of a previously cut strip. Arms 340 and 340' are disposed from masts 313 and 313', respectively, at an angle .theta. relative to the negative of the vehicle's velocity vector S.sub.v. To reduce crabbing, axes "b" of inbound buckets are skewed in the direction of the vehicle's motion by angle .phi. relative to axis "c" of the track 342. Generally, angle .phi. is in accordance with the relation

.phi. = .theta. - tan.sup..sup.-1 (S.sub.c sin .phi./S.sub.v + S.sub.c cos .phi.)

where S.sub.c and S.sub.v are the scalar speed of the buckets and of the vehicle, respectively. To maximize the width of the strip, angle .theta. is maintained at 90.degree. so the angle .phi. = 90.degree. - tan.sup.-.sup.1 (S.sub.c /S.sub.v). By appropriate gearing between the crawler drive-motor of vehicle 301 and drive sheave 344, speeds S.sub.c and S.sub.v are proportional so that the ratio (S.sub.c /S.sub.v) and the proposed skewness .phi. of bucket axes "b" are essentially constant.

Still referring to FIG. 11, lights 358 and 358' illuminate areas in front of sheave tractors 356 and television cameras 359 display the terrain on monitors in control room 125e of the ship. Camera 359 displays edge 380 of the preceeding strip so that an operator in the control room may steer behicle 301 to clear an abutting strip. Scanning sonars 360 mounted on tractors 356 scan the surface to warn of impending obstacles and hazardous terrain, penetrating cloudy water that may obscure television images.

THE BUCKETS

FIG. 12 is a close side view of two representative buckets, outbound inverted bucket 351b riding upper track 342b and inbound righted bucket 351a riding lower track 342a. FIG. 12A is a front view of righted bucket 351a and shows the relation between bucket input axis "b" and track axis "c." Buckets 351 have an open front and bottom, a partially closed top, fully closed sides and back. Each bucket slides on a pair of broad ski-like runners 353 and 354 the height of each being adjusted by means of slotted fasteners attached to each side of a bucket. Downstream runner 354 is flush with the bottom of the back of the bucket while upstream runner 353 is adjusted to a height equal to the thickness of the layer 343 to be cut as judged by samples previously taken of the bed. The disparity in runner heights enables the bucket to ride level with runner 353 gliding along undisturbed ground while runner 354 rides on a previously scraped surface. Both bucket sides extend slightly below the runners. Fastened to the back of the bucket is a cutting block with a toothed edge 352. The cutting edge of the block scrapes the surface causing nodules to accumulate in the bucket and the teeth permit some of the unwanted clay and mud to escape.

The buckets have a paritally closed top for the attachment of four flanged wheels 355 and fasteners that link the top with the chain. As is more clearly detailed in FIG. 12A, upper track 342b and lower track 342a each comprise a pair of light railway rails. Flanged wheels 355 ride along the heads of a rail. The support of the inbound buckets help hold the track structure in the vertical plane.

THE TRACK

The track structure is thin to make it limber in the vertical plane so that the system of buckets can follow gentle irregularities in the bottom topography. Transverse stiffness to keep the buckets in line is supplied by a series of ties and cross bars 342c shown in FIGS. 12 and 12A that extend orthogonally and diagonally between the rails of each track.

The two ends of the track are illustrated in FIGS. 13 and 14. Track rails terminate in rigid supporting members at both ends. At the near end of FIG. 13, lower track 342b bends upward so that incoming buckets may be elevated to deposit their loads in trough 308. The upward bend starts over the point where inclined plate 308a of the vehicle of later FIG. 15 emerges from the ground. Lower and upper tracks 342a and 342b terminate in supporting member 370 which bends upward over the point where buckets 351a meet plate 308a.

The distant end of the track is shown in FIG. 14. Upper track 342b bends upward while lower track 342a remains horizontal and in close proximity to the chain. Both tracks terminate into support member 372 rigidly connected by swivel frame structure 357 to tractor 356. The terminal points of the tracks are close to tail sheave 345. The terminal point for lower track 342a is as close as possible to where the rounding buckets assume a righted position. A hydraulic actuator 362 is provided in structure 357 to raise the outer end of the track when tractors 356 are maneuvering into position or the miner is moving to a new area.

For support additional to that provided by the buckets and to provide stability at its center, each arm is provided with a pair of wheels (not shown) that are wide enough to avoid sinking into the clay. These are mounted in the vicinity of the midpoint of the arm, one to the front of the track and the other to its rear. They are separated by about three or four meters and prevent the arms from tipping.

Endless chain 350 is composed of many long links that mate with the flats of drive sprocket 344 and tail sheave 345. Drive sprocket 344 is coupled by gearing to the output of the crawler drive motor of vehicle 301. Buckets 351 are mounted at points on the chain of each arm so that there is no interference between the two sets of buckets over trough 308.

Servo units in the miner maintain angle .theta. at 90.degree.. Limit switch 337 linked to each mast 313, as shown in FIG. 15, senses angle .theta. and issues appropriate speed adjustment command signals to sheave tractors 356 and 356'. As is discussed again subsequently, a decreasing angle .theta. causes switch 337 to provide a signal for increasing the speed of tail sheave tractors 356 and 356', whereas an increasing .theta. causes switch 337 to slow down the tail sheave tractors. Tension transducer 361 of earlier FIG. 14 measures the tension of each track along its longitudinal axis. It generates steering signals for constraining the movement of tractor 356 along a path parallel to tractor 301. If tail sheave tractor 356 deviates from a parallel course, corrective commands are sent to a steering mechanism in tractor 356. Both control systems are described in conjunction with later FIGS. 17 and 18.

PARAMETERS OF THE ARMS

To utilize the buckets efficiently, they should be spaced so that the swath of any bucket overlaps somewhat that made by the preceeding one. The following specifications for the arms suppose an average advance rate S.sub.v of 0.2 m/sec. which should be reasonably sufficient to mine ore over a typical deposit at a rate of 500 tons/hr. Exemplary specifications are:

Extended length of each arm -- 50 meters

Height of the arms including mounted buckets and two tiers of tracks -- 1.05 meters.

Scraper chain speed, S.sub.c, -- 1 meter/sec.

Length of each chain link -- 0.5 meters.

Bucket capacity -- 0.5 meters.sup.3.

Bucket width -- 1 meter.

Width over outside of bucket runners -- 1.7 meters.

Angle .theta. of 90.degree. and angle .phi. of 11.degree..

The nodule-gathering apparatus as just described is a vital part of the system; and the success of the system requires that it operate reliably, and unattended, for long periods of time. It is, however, not necessary that details of this apparatus be as described and shown in the drawings to fall within the spirit of this invention.

There are other kinds of gathering apparatus which may effectively span a wide mining strip.

It is necessary that the gathering apparatus extend out a substantial distance, of the order of 100 meters, from the vehicle where the ore is collected in a trough or other receiving means. It is further a feature of my invention that the gathering be accomplished by a mechanical conveyor which scrapes the ocean floor along a path extending from its proximal end at the vehicle to its distal end at the edge of the strip. It may be that a screw conveyor or the like may be used; but one or another form of endless belt or chain of buckets is contemplated to be preferred depending on various design factors. In these the endless scraper scrapes along the distance from a tail sheave at the edge of the strip inward to the vehicle. The invention further requires that propulsion means be provided to move the collecting means with the vehicle while extended to span the strip. I prefer that this be provided by a tractor carrying the tail sheave; but clearly the tail sheave might be carried by a sled which would be towed by a tractor and kept at its distance by the angle of its runners.

I prefer that the position of the buckets be positively controlled by indexing their wheels to a track with vertical flexibility, and that they be propelled by a chain; but they might be drawn like so many skiers on a rope tow.

On their return to the tail sheave, I prefer that the buckets be carried on the track out of contact with the ocean floor, but the scraper means might well be supported on this return trip by passing over one or more sheaves held off the ground by floats; or might be pulled back over the ground in a reversed non-scraping orientation.

While I believe that a chain of buckets or scrapers is preferred, it is possible that the nodules may be scraped up and carried by an endless belt, weighted at its lower edge by a steel cable, and bouyant at its other edge. This may have angles cleats along the heavy edge to urge it against and into the material to be recovered.

Generally the collecting apparatus will extend laterally from the vehicle that is in a direction, preferably and generally normal to the velocity vector of the vehicle, and being flexible will not necessarily extend in a straight line, but rather adopt some optimum curve, and may angle considerably forward or backward while extending laterally.

THE TRACTORED VEHICLE

Referring again to FIG. 15, tractored vehicle 301 comprises an ore-delivery component followed by cleaning and crushing apparatus mounted on a tractored chassis. With the aid of FIG. 11, it is observed that plow blades 309 and 309' are followed by inclined plates 308a and 308a'. The blades push ore directly in front of the vehicle to its sides where it is gathered up by the incoming buckets. The inclined plates terminate sharply into trough 308. The plow and inclined plates ride on a pair of flat runners 310 and 310' that, though only partly shown, extend back and end just short of the vehicle's tracks. The runners control the cutting depth of the plow blades. Mounted on each inclined plate is a telescoping rotary mast 313 or 313' supporting driving sprocket 344 and the prozimal end of the corresponding arm. The masts are located at points on the inclined plates to permit them to swing about 180.degree. without interference. As better shown in FIGS. 11 and 13, the masts are connected to the drive sprockets through an inward pointing member 313a so as to reduce the slope at which the buckets must climb the plates before depositing their loads in trough 308. Masts 313 and 313' telescope and swivel by operation of motors mounted under plates 308a and 308a'.

Base 301a of the vehicle houses the mechanisms that drive the tractored wheels. The mechanisms are actuated by crawler drive motor 302. Because of the softness of the bed, the tracks are sufficiently wide to support the vehicle. The necessary width for the tracks is determined from samplings taken of the bed prior to the lowering of the plant.

Mounted on base 301a is cylindrical nodule cleaner 320 and ore crusher 303. Cleaner 320 is slightly inclined with its output end tipped toward the inlet of crusher 303. Nestled in the base underneath ore crusher 303 is surge bin 304. This bin is carried by a weighing transducer 389, (not shown) illustrated in later FIG. 19, that provides electrical feed back signals to the servo loop that controls crawler drive motor 302 and the advance rate of the vehicle. At its bottom, surge bin 304 is emptied by outlet pipe 305 which was rigidly coupled to the first hoist pipe at the beginning of the lowering sequence. Rods 338 support the outlying portions of the miner during the long trip to the bottom, when all its weight is supported by outlet pipe 305.

Cylindrical cleaner 320 slowly rotates about its longitudinal axis. The rotary drive is provided by interaction of gear 333 installed on the outer rim of the cylinder and drive motor 321. The cylinder is supported by a pair of trunion rings 322 which ride on rollers 322a fixed to the base.

Feedline 307 extends from the bottom of trough 308 through pump 306 and freely projects into cleaner 320 through a large aperture in its elevated input end 328. Feedline 307 has a tap-off valve that couples into a large ballast bin with a capacity of at least 20 tons and a bottom dumping hatch (all of which are not shown). The initial load of sediment composed of mud and nodules deposited in trough 308 is fed into the ballast bin until it is filled whereupon the valve is shut and the rest of the sediment is fed into the cleaner. After the removal of clay and mud, cleaned ore 343b escapes from the cleaner at output end 322 and falls into crusher 303 where it is reduced to particles of 1 cm. or less in diameter. Ore processed by the crusher falls from its bottom into outlet pipe 305 where, by action of a pump in outlet pipe 305 or the pump of the first hoist pipe, it is transported into the hoist pipe circuit up to the hovering Sessile ship. Servo-controlled valve 314 admits sea water to mix with the rising slurry to keep the concentration constant. Manifold 312 mounted on the base distributes clean water to the many water-lubricated bearings used in vehicle 301.

ORE CLEANER

Details of the ore cleaner 320 are illustrated in the cross-sectional side view of FIG. 16. It comprises a cylindrical chamber about 2 meters in diameter and 6-9 meters in length. Elevated input end 328 has a large aperture whereas output end 332 is fully open. Midway through the chamber is a helical baffle 327 open at the center. The helix is fastened to the cylinder and revolving with it. The helix controls the stream of nodules and fine ore particles 343a sliding down the incline of the clinder and prevents their escape while being stirred and washed. A water pipe 325 passes through the open center and has several output nozzles 326 that discharge cleaning water on the ore. The output of these nozzles is sufficiently close to the stream of nodules to reduce frictional losses between the jets and the surrounding water. The pipe is made rigid enough to withstand the reaction of the downward pointing jets even though it is only supported at its ends.

Clean water for pipe 325 is derived from intake pipe 324 which extends to a clear zone a distance of between 200 and 300 meters vertically from the cleaner. The intake pipe passes through pump 323 and coupled into central pipe 325 at the output end of the cleaner.

A combination of the tumbling motion induced by the rotating helix and the agitation of the water jets separates the fine mud from the ore particles. The fine mud rises in cloud 330 and escapes out the openings in the two ends of the cylinder. The heavier ore particles and nodules 343a remain at the bottom of the cylinder while the finer particles are prevented from escaping by the helix. The ore finally moves down to output end 322 and falls into ore crusher 303.

ORE CRUSHER

Ore crushers are common in mining. A number of commercial units may perform the function presently contemplated, so a description of the structural and operational details of crushers is though unnecessary. However, certain considerations enter into the design of a preferred embodiment for crusher 303.

As is mentioned at the outset of the specification, the average diameter of nodules on the ocean floor is about 3 cm. So few may be expected to exceed a diameter of 10cm that the inlet of crusher 303 may be restricted to 10 cm without incurring a significant economic penalty. A "secondary" type crusher (one with intake limited to small sized solids) is preferred for this application. Although they have a restrictive inlet, they have a larger hourly capacity. The latter feature is more important and fortunately imposes little if any operational penalty.

To avoid the high drag that accompanies the high speed flywheels of the Blake type, the "secondary" crusher is of the gyrator type. The opposing ore crushing surfaces are lined with a "hard" substance that is corrosion and wear resistant, such as alumina blocks. The bearing of mechanically interacting members, such as that of the eccentric drive cones and surrounding pressure cones, are water lubricated. As water has a much lower viscosity than the oil used in gyratory rushers, the bearings are designed with a larger diameter than that adopted in conventional units. Bearing clearances are reduced to compensate for the lower viscosity of the water lubricant. High stiffness and minimum friction is sought for the bearings. They are made of very thin rubber, for example, in the order of 1 mm on a conical bearing of 60-80 cm. diameter.

SERVO CONTROLS

Illustrated in FIGS. 17 and 18 are two systems for controlling the direction and speed of tail sheave tractors 356. FIG. 18 illustrates a steering control system functioning with the command signals of tension transducer 361 of FIG. 14, and FIG. 17 shows a proposed speed control system utilizing the command signals of limit switch 337 of FIG. 15. Referring first to the steering control system of FIG. 18, tension transducer 61 comprising spring 361a in series with a pair of collars 361b-361c is connected between the frame of mast 357 and structural member 372. Collars 361b and 361c cooperate respectively with heavy and light tension switches 361d and 361e. When triggered by movement of the collars, switches 361d and 361e activate re-cycling timers 363 and 365, respectively. The timers energize one of clutch solenoids 447 or 449 to disengage briefly one track from drive shaft 452 for purposes of turning the tail sheave tractor in the appropriate direction by a small angle, say 1.degree.. If the turn is insufficient to release the switch, the timers re-cycle after a short period, for example 30 seconds, to cause successively small turns in the same direction. Thus, an inward deviation of tractor 356 compresses spring 361a and declutches the drive to outer track 451, while elongation of the spring declutches track 453. The corrective action of the steering control to unwanted deviations of tractors 356 and 356' keeps them within maximum and minimum angular limits and on an average course essentially parallel to the travel of tractored vehicle 301.

A speed control system for maintaining angle .theta. approximately constant on the average is illustrated in FIG. 17. Limit switch 337 coupled to mast 313 is connected electrically by line 363 to gearbox 455. The gearbox has two sets of gears, one set of which is operative at any time to couple drive motor 459 of tail sheave tractor 356 to drive shaft 452. The two gear sets provide an incremental step in the drive speed, say a 1 percent change, of shaft 452. For example, gear set 446-446a may have a tooth ratio of 201/200, and gear set 448-448a the inverse. The gears are coupled to shaft 452 by action of bi-state solenoid 444 which operates clutches 449 and 453. The state of solenoid 444 depends on which of the two limiting signals of switch 337 is carried by line 363. When angle .theta. exceeds 90.degree. by a specified angular limit, solenoid 444 is energized to engage step-up gear pair 446-446a to decrease the speed of the tractor by 1 percent. Similarly, when angle .theta. reaches a lower specified limit, step-down gear pair 448-448a is engaged with shaft 452 imposing a 1 percent increase in speed.

While gearbox 455 provides an immediate but small adjustment in speed, a requirement for gradual and greater variations is satisfied by adjusting a governor regulating the speed of drive motor 459. Still referring to FIG. 17, limit switch 337 is parallel connected to reversible control motor 461 which is coupled to governor 463 through a large step-down gearbox (not shown). The step-down gearing affords a slow adjustment in the governor's setting, say 1 percent per minute, in response to signals from switch 337. Governor 463 regulates motor speed in the usual way with spring actuated switch 467 sorting series winding resistor 465 when motor speed is less than that ordered by the governor, and reinserting the resistor when the motor speed is excessive. Thus, when angle .theta. of the scraper bucket arm attains its maximum specified limit, reversible motor 461 gradually increases the governor setting, and conversely decreases the setting when angle .theta. reaches its minimum specified limit.

The effect of such variations in the operating speed of motor 459 complements step speed changes produced by gearbox 455. If the speed required of the tail sheave tractor is not within the 1 percent adjustment capability of the gear change, one of the contacts of switch 337 will be operative for a longer period than the other and the net change in the governor's setting is in the direction required to achieve orthogonality in the scraper bucket arm. The speed adjustment will continue at a slow rate until the tractor is running at a speed very close to that desired. The intervals of high and low speed operation of the gearbox will become equal and no further net change in governor setting will occur.

The advance rate of the plant is regulated by the speed control for the crawler drive motor 302 of vehicle 301 appearing in the functional block diagram of FIG. 19. Surge bin 304 of earlier FIG. 15 offers a measure of the difference of the flow rate of ore processed by the vehicle and the rate of ore hoisted by the pipe circuit. Controls, including servo control valve 314 maintain the desired flow rate and ore concentration in the pipe circuit, here about 500 tons/hr. The crawler speed control of FIG. 19 adjusts the advance rate S.sub.v to keep the two rates equal. The initial rate of speed for the control is set according to the ore density of the field previously determined from a sampling tube. However, as the field is mined, weight transducer 383 for surge bin 304 provides a control signal W. Weight reference signal S'.sub.v transmitted from the control room of the Sessile ship corresponds with a specfied quantity or weight of ore to be maintained in bin 304, preferably the weight of the bin when half-filled with ore. Output W of transducer 383 is compared with weight reference signal S.sub.v ' and error signal "e" results to vary the speed of crawler drive motor 302 appropriately until the vehicle's speed S.sub.v is such to hold the reservoir of ore in bin 304 as specified (half-filled). A scraper bucket chain drive proportional to speed S.sub.v derived through gearing between the output of crawler drive motor 302 and drive sheave 344. This coupling allows a chain speed S.sub.c proportional to vehicular speed S.sub.v and the ratio (S.sub.c /S.sub.v) to be maintained reasonably constant, as was discussed above.

MOTOR DRIVES

The several motor drives used throughout the lower portion of the system and miner 300 are specially designed to avoid the need for tightly sealed and expensive cashings ordinarily required in a high pressure environment. Referring now to FIG. 20, a typical motor drive comprises a motor housed in casing 400 located below gear box 420. The chamber of casing 400 is filled with distilled water 413 that is electrically insulating and immiscible with the oil in gear box 420 and has a specific gravity greater than that of the oil. Water 413 fills casing 400 from "O" ring seal 426 at the junction of the casing and gear box 420 to the bottom where it envelops the closed surfaces of expansion bellows 415. As with a similar bellow 419 located in the shell of gear box 420, bellows 415 have outward facing openings that receive sea water. Immersed in the distilled water is the stator 405 and a rotor 410 that is mounted on the shaft 409. The bottom of shaft 409 rests on rubber-lined, fluid-lubricated bearing 412, wiile the top of the shaft is mounted on ball bearings 424. The drive of shaft 409 is coupled to the motor's output shaft 425 and its rubber-lined, water-lubricated bearing 427 through meshed gearing 422 in box 420. Gear box 420 is filled with lubricating oil of light density and high viscosity, say with a specific gravity of 0.89 and a viscosity of about 90cs. The gearbox is sealed from the sea by "O" ring seal 426. The outer surface of casing 400 has a thin layer of insulation 400a but with enough leakage to allow some of the heat generated inside the motor to dissipate. Solid material, such as alumina oxide, high melting point wax paints or plastics, are suitable insulators.

Functionally, the chilling temperature of the deep sea environment contracts the oil and water inside the motor causing bellows 415 and 419 to adjust in volume until the pressure differential across the motor's housing is substantially reduced. Through action of "O" seal 426, the pressures of distilled water 413 and the lubricating oil tend to equalize. These adjustments in the pressure differentials both internal and external, and the natural segregation of the oil above the water in casing 400, tend to simplify the sealing problem and allow the use of "O" seals 426 instead of more expensive tighter ones at mechanical junctions.

MINING PLAN AND SYSTEM RETRIEVAL

In mining an ocean bed, flat areas are covered in a straight strip while abyssmal hills are worked along a spiral path. When an area is sufficiently covered and the plant is to be transferred to a new site, arms 340 and 340' are rotated forward of vehicle 301 (.theta..DELTA.180.degree.) and tail sheave tractors 356 and 356' are aligned with the vehicle. Alternatively, the arms may be folded again with the aid of winch 339 and the plant moved in the orientation of FIG. 9.

The retrival procedure basically is the reverse of the assembly process. The miner and pipe sections dump their loads and the arms are folded into the arrangement of FIG. 9. Upon being lowered from the ship, the Manbot connects one hoist cable, say cable 133, to the (n-1)th pipe section. The cable gradually assumes the load of the system while flexible pipe 295 and float 290 are de-coupled from the nth pipe section by scuba divers. After electrical cable 127 is disconnected from terminals of the nth pipe, the junction between that and the (n-1) th pipe section is disengaged by the Manbot. The nth pipe is guided to the surface with the aid of a line between it and motor launch 10. The system is then elevated one pipe length by cable 133 and the Manbot next connects the second hoist cable 137 to the (n-2)th pipe. Cable 137 then assumes the load while the (n-1)th pipe is disconnected by the Manbot and guided to the surface. The remaining pipe sections are disengaged in the same manner, the system being raised one pipe length at a time with the top most pipe guided to the surface after being freed.

Finally, when only the first pipe section remains, one of the hoist cables is run down central well 121 and linked-up with outlet pipe 35. The load is then transferred gradually to the axis of the ship. The free cable is likewise run down well 121 and the Manbot one of the lines with each of joints 346 of the arms. The top winches of the first pipe section are disconnected from joints 346 whereupon the pipe is freed of outlet pipe 305 and guided to the surface. The miner is centrally positioned along the axis of the ship for its final return and clamping to the ship's bottom as in FIG. 2.

Having thus described a preferred embodiment of his mining system, applicant now defines his invention in the appended claims.

* * * * *

Current U.S. Class:	299/8 ; 37/308; 37/310; 37/314; 37/324
Current International Class:	E02F 7/00 (20060101); E21C 45/00 (20060101); E02F 5/00 (20060101); E02f 007/00 ()
Field of Search:	299/8,9 37/DIG.8,58,72