US3545812A

US3545812A - Underwater mining apparatus

Info

Publication number: US3545812A
Application number: US747199A
Authority: US
Inventors: Melvin W Smith; Charles S Kluth
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1968-07-24
Filing date: 1968-07-24
Publication date: 1970-12-08
Anticipated expiration: 1987-12-08
Also published as: DE1936777A1; FR2013600A1; NL6911146A; SE356778B; GB1228263A

Description

United States Patent m Inventors mmw. s-nu 1.55 .657 9/1925 Goeriz soz/i v 1.6! 1,478 l2/ I926 Massey 302/ I4 l W Sim Primary Examiner-Andres l-l. Nielsen ,E.P.Kl'fl dD.Sch Filed u m Attorneys F H Henson ip e an ron [4S] Patented Dec. 8, I970 [73] Assignee WestinghouseElectr-lc Corporation l'lttsburgi, Penney lvanla mm M Pmmhuh ABSTRACT: A surface vessel for an underwater mining system which utilizes (a) a bottom collector, (b) conduit exlsl uNnuwA-"m Mums APPARATUS tending between the vessel and the bottom collector for transporting collected material. and (c) a gas lift system for raising c 7 Dun." collected material. The surface vessel includes a plurality of [52] US. Cl. 302/14 naive. bins connected to the condui for receipt of counted 53/o4 material. Associated with each bin is an air vent trunk open to [50] misfit. 302/, Is, he upper part d the receiver bin and emu-ding downwardly through the surface vessel where it is communicative with the Re cued ambient sea water at the bottom of the surface vessel. [56] m After selected receiver bins are full, the collected material is UNITED STATES PATENTS removed. dried and transported via conveyors to storage areas l,3 l6,507 9Il9l9 Pollard 302/ I4 aboard the surface vessel.

vmtmauumwm I 5.5545812- same 0F 2 STARB AR 1 r UNDERWATER MINING APPARATUS BACKGROUND OF THE INVENTION l. Field of the Invention- The invention in general relates to the field of material lift and collection systems, and particularly to a structure particularly adapted for use, in underwater mining systems.

2. Description of the Prior Art Underwater mining systems have been proposed wherein gas under pressure, forv example compressed air, is introduced vided by the collector. I

As the bubbles rise tothe surface they expand due to the decreasing pressure and are traveling at extremely high velocities. Where mining operations are carried out at many thousands of feet below the surface of the water the velocity of the material discharging-fromthe conduits to a receiver on the surface vessel is so high and the area of the conduit occupied by the air is so large that the daily production rate of material,

for example, aggregates in the form of manganese nodules, is

very low. Increasing the air supply increases the velocity and the discharge rate at the surface, however, the volume of conduit'occupied by the aggregates is reduced and the requirement for a high production rate .is not met solely increasing the compressed air supply.

One proposal for increasing the production rate is to discharge the upper portion-of the conduit into a pressure ves sel to slow down thedischarge and apply a back pressure on the system. The pressure vessel has an outlet which is conducted through a filter network back to the compressor for the compressed air system. The prior art apparatus necessitates the continual replacement of the filters for compressor protection, however, even with filter replacements the air under pressure being fed to the compressor is stillcontaminated with salts, and in some instances some sulfides. The salt attacks the compressor components and a chemical reaction is possible whereby if any sulfides are collected, sulfuric acid could be formed which when constantly recirculated severely reduces the life ofequipment.

It is therefore a general object of the present invention to provide in a system of the type described, a structure which applies a back pressure to the gas lift system being utilized to significantly increase production rates while not having an adverse affect on the compressorutilized.

Other general objects are to provide a relatively simple.

SUMMARYO-F THE INVENTION Basically, the invention includes a receiver means in an un- I derwater material collection. system utilizing (a) a bottom collector and surface structure at respective first and second vertically spaced points with Y (b) conduit means extending between them and (c) a gas lift system introducing compressed gas to the conduit means to raise collected material.

The conduit means is communicative with the' receiver means for deposit of collected material and back pressure is effectively put on the gas lift system by provision of a discharge means connected with the receiver means and including a discharge aperture disposed to discharge gas against a liquid pressure such as by location below the surface of the water. A

Where the material collected is in the form of aggregates, transfer means is provided for transferring the collected aggregates to storage means and'in the process of transfer the aggregates are heat treated to aid in drying.

. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates the basic components of an underwater mining system;

FIGS. 2 and 3 are graphs illustrating relative areas in the conduit of FIG. 1, occupied by collected material at two different pressures;

FIG. 4 is an isometric view, partially in section, partially in phantom, with portions broken away, of the surface vessel of FIG. 1;

FIG. 5 is a cross section through the surface vessel of FIG. I;

FIG. 6 is a plan view of a flow path diagram; and

FIG. 7 is a schematic representation of a heat flow and heat transfer system for drying collected material.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, there is illustrated by way of example a typical underwater mining system including a surface vessel 10 which travels through the water in the direction of the arrow. Depending from, and towed by, the surface vessel 10 is a conduit means,conduit 12, connected to a collecting means, bottom collector l4, vertically displaced from the surface vessel 10 and which travels on the sea bottom 16. The conduit 12 may bedivided into a plurality of segments joined together by means of swivel,-or ball joints 19 and 20. One type of collector which may be utilized is described and claimed in copending patent application Ser. No. 729,728 filed May 16,

I968 and assigned to the same assignee as thepresent invention.

In order to-convey the collected aggregates or other material from the collector 14 to the surface vessel 10 via the conduit 12, a compressor onboard the surface vessel 10 supplies a gas such as air under pressure to the conduit 12 at the injection point I. The compressed air is introduced as small bubbles which rise through the column of water in the conduit 12, which action draw up material from the collector 14.

Depending upon the depth of mining operations, the compressed air introduced into the conduit at injection point I may be at a pressure of hundreds or even thousands of pounds per square inch (p.s.i.). The air'rises through the conduit 12 to an atmospheric pressure of approximately 14.7 psi. at the surface vessel 10, and in so rising increases in velocity and expands to occupy a substantial area of the conduit, such as illustrated in FIG. 2 to which reference is now made.

In FIG. 2 the circle 25 is illustrative of the cross-sectional and sea water, when the' conduit discharges to atmospheric pressure at the surface vessell0. The remainder of the conduit is occupied by the expanded air as represented by the unshaded area 29. The discharge of material represented by the shaded area 27 may be defined by the formula 0 AV, where Q is the discharge rate, A the area represented by the shaded portion 27, and V the velocity of the material at discharge. In the situation illustrated in FIG. 2, the area A is extremely small and even though the velocity may be in hundreds of feet per second, the consequent discharge rate and accordingly the production rate is relatively small. 1

At a point further down the conduit 12 where the pressure is greater, it is seen that the compressed air as represented by the unshaded area 29' has not completely expanded and accordingly the area occupied bythe material, as represented by the shaded portion 27'is much greater than that of FIG. 2.

Although the velocity of material in the situation of FIG. 3 is reduced, the discharge O is significantly increased due to the manifest increase in area, A, of material.

In the present invention the situation as depicted in FIG. 3 is recreated at the surface vessel by means of the structure illustrated in FIGS. 4 and 5. Many mining vessels include a center well portion through which collector, conduit and associated equipment may be lowered. The center well 37 may be best seen in FIG. 5, with a protective grating 39 at the deck level best seen in FIG. 4.

Conduit 12 extending downwardly through the center well 37 to the collector on the sea bottom passes through and is held by a girnbal 42 supported by structures 43, and operative to rotate about first and second axes perpendicular to one another in order to accommodate for pitch and roll of the vessel 10 during mining operations, such gimbals being well known to those skilled in the art.

The surface vessel 10 includes a receiver means preferably in the form of a plurality of receiver bins of which two, forward starboard and

port receiver bins

34 and 34 are illustrated in FIG. in cross section.

During mining operations aggregates conveyed by conduit 12 are concurrently deposited in closed receiver bins 34 and 34'. When these two bins are filled, the collected aggregates are deposited in aft starboard and port receiver bins (not shown) while the forward starboard and port receiver bins 34 and 34' are emptied. To direct the collected aggregates to the proper starboard and port receiver bins there is provided a deflector 45 having diverging

arms

47 and 48 connected through respective ball joints 51 and 52 to

conduits

12a and 12d by means of respective slip joints 57 to 60.

A clearer understanding of the deflector 45 and its connection may be had by reference to FIG. 6 which is a plan view of a line diagram illustrating flow paths and wherein components identical to those in FIGS. 4 and 5 have the same reference numerals. When the forward starboard and port receiver bins 34 and 34' are being filled, valves VI and V2 are open while valves V3 and V4 are closed. Subsequent to the filling of receiver bins 34 and 34' valves V3 and V4 are opened so that collected aggregates may be deposited in the aft receiver bins and valves VI and V2 are closed. The contents of

receiver bins

34 and 34 are then removed and the cycle is repeated so that they may thereafter receive the aggregates conveyed by the conduit while the aft receiver bins are unloaded.

Referring back to FIGS. 4 and 5, at the top of the-deflector 45 there is illustrated a pipe 63 which is connected to a suitable compressor means (not illustrated) below decks for supply of compressed air or other compressed gas. A compressed gas lift system which maybe utilized herein is further described and claimed in copending patent application Ser. No. 736,036 filed June II, 1968. now US. Pat. No. 3,526,436 assigned to the same assignee as the present invention.

Each of the receiver bins is communicative with the conduit 12 by means of respective conduits 12a to l2d, the deflector 45, and valving arrangement therefor. By way of example, and as best seen in FIG. 5, conduit 12a is disposed for depositing collected aggregates 66 into the starboard receiver bin 34. Conduit 120 includes a flanged end portion 67 which may be clamped or bolted to a mating flange 68 connected to a short section of conduit 70 extending through the deck 72 of the surface vessel and in airtight relationship therewith. Similar components on the port side of vessel 10 have been given primed reference numerals herein and an explanation of the components associated with receiver bin 34 is equally applicable to those associated with receiver bin 34'.

In order to apply a back pressure on the gas lift system, and it is assumed that compressed air utilized, there is provided discharge means communicative with the receiver bin 34, the discharge means including a discharge aperture below the surface 74 of the water. By way of example, the discharge means takes the form of an air vent trunk 76 communicative with the receiver bin 34 by means of an or an aperture 78 in side wall portion 80 and communicative with the ambient sea water by means of aperture 79at the bottom of the vessello'and vertically spaced from the aperture 78. A screening means 81 is provided for the aperture 78 for preventing the lossof collected aggregates and the clogging the air vent trunk 76.-

Discharge aperture 79 is opened to theambient sea water and consequently prior to mining operations the. level of the water within the air vent t'runk 76 rises to the level 74 shown dotted, said level being identical with the ambient water level. During mining operationswith the air liftsystem in use, conduit 12a discharges, intothereceiver bin 34, aggregates 66 in addition to air and sea water. The receiver bin 34 is airtight except for the aperture 78 which allows for overflow and exhaust of the compressed air. The exhausting of the air is opposed by the column of water It in the air vent trunk 76 which column is forced through the discharge aperture79. 'A pressure P hd is effectively placed upon the air lift system, where): is the h of FIG. 5 and d is the density of the 'sea water. The continual discharge of air from the dischargeap'erture 79 insures thata back pressure maintained in the receiver bin 34, that is,'a back pressure is effectively maintained on the air lift system so that instead of discharging to atmosphere pressure the aggregates are discharged to a pressure P,, to stimulate the conditions illustrated with respect to FIG. 3.

Discharge of air from the discharge aperture 79 at the bot tom of air vent trunk 76, results in large bubbles which may induce considerable hull noise in the surface vessel 10. Ac-. cordingly, there is provided screening means 83 for the discharge aperture 79 to break up the large volume of exhausting air into small bubbles. The air vent trunk 76 with the discharge below the surface of the water not only effectively provides a back pressure but in addition, the exhausting air is washed to aid in elimination of odor caused by collected material.

In some instances it may be desirable to apply a back pressure greater than P and accordingly there is provided valve means 87 operable to restrict the size of the discharge passageway of air vent trunk 76. The valve means 87 includes a valve 88 interposed between apertures 78 and 79 for restricting the area of the passageway therebetween. The valve 88 is connected by means ofa valve stem 89 to a handle 90 which is manually or otherwise operable from the deck 72 of'the vessel 10. The valve stem is held by and is in substantially airtight relationship with a hatch means 92 which is removable not only for servicing the valve 88 but for conveniently replacing screening means 81 and 83 when needed.

Alternatively or in addition to the use of valve means 88 it would be possible to provide a second air vent trunk within the air vent trunk 76 and which second air vent trunk would be slidably extendible below the bottom of the vessel 10, thus increasing the value of the h of FIG. '5, and, with this increase, the amount of back pressure maintained.

The lower portion of the receiver bin 34 has sloping wall portions of which three, 95, 96 and 97 may be seen in FIGS. 4

and 5. These sloping wall portions insure that the collected ag-.

gregates 66 within the receiver bin 34 are directed to a central area where they may conveniently be collected and removed from the receiver bin 34. The collection and removal means includes a vertically traveling bucket ladder conveyor 100 which extends from the lower portion of the receiving bin 34 to a position above the deck and which is surrounded (except for the lower portion) by an enclosure 102 of suitable airtight construction to maintain the back pressure during collection operations.

When the forward starboard and port receiver bins 34 and 34' are filled and are ready to be unloaded, valves V3 and V4 (FIG. 6) are opened so that the aft, starboard and port receiver bins may receive collected aggregates. Thereafter.

gregates picked up in the receiver bins 34 and 34'into hoppers'107 and 107" which in turn direct the aggregates onto a first set of longitudinal conveyors 110 and 110' forming a poition ofa conveyor means for transferring collected agg'rega'tes from the receiver bins to storage holds. a

The surface vessel 10 includes conventional forward andaft cargo holds for storage of collected aggregates. When the forward cargo holds are to be loaded, conveyor Il0.traveling in the direction of the arrowshown deposits aggregates unloaded from the receiver bin 34 onto a first transverse conveyor I13 l00 and 100' when placed into operation may dump ag-' by means of chute 114. Conveyor traveling in the direction of the arrow deposits aggregates onto a second transverse conveyor 117 by means of chute 118.

By means of transfer mechanisms such as trippers 121 and 122 the aggregates on transverse conveyors 113 and 117 may be transferred to a second set of longitudinal conveyors 125, i

- veyor system and any operating personnel from the elements,

that is, the effects of wind, precipitation and adverse seas.

. Conveyors 125 to' I27 emerge from the housing via

protective trunks

134, and 136, respectively, which extend longitudinally'abov'e the cargo holds below deck 72. Hatch means such as

hatches

139 and 140 are disposed above a first cargo hold and are covered by means of

deck structures

143, 144, respectively, which although shown broken away in FIG. 4 in actuality extend longitudinally over other hatches communicative with other cargo holds (not shown) in the forward portion of the surface "vessel 10. The flat top surfaces of the deck structures 143m 144 constitute hatch covers while the vertical walls of the

deck structures

143 and 144 are commonlytermed coaniings'. The coamings of the

deck structures

143 and 144 include gating-means such as gates 146 to 149. Basically the gates are provided on the outboard and inboard coamings of the

deckstructures

143 and 144 to selectively receive the aggregates carried by the conveyors 125 to 127.

Transfer means well known to those skilled in the art may be utilized for directing the aggregates carried by the conveyors through selected gates, through the hatches and into the holds below.

Gates on the inboard co'amings are provided to receive aggregates carried by the middle conveyor126 whereby a more complete utilization of hold volume is achieved. The aggregates may be transferred onto conveyor 126 from one or both of conveyors 113 and 117 by repositioning of trippers 121and122. f

in order to'load the aft cargo holds there is provided an arrangement similar to that for loading the forward cargo holds.

More specifically,

longitudinal conveyors

155, 156 and 157 emerge from the rear of housing 130 in respective

protective trunks

159, 160 and 161 extending along side and between deck structures 164 and165 covering hatches communicative with one or more cargo holds. Although not illustrated in FIG. 4, in the aft section of the housing 130 there would be in cluded transverse conveyors similar to transverse conveyors 113 and 117 which would receive aggregates from longitudinal conveyors 110 and 110' traveling in a direction opposite to that indicated by the arrows on these latter conveyors.

After

forward receiver bins

34 and 34 have been emptied and the collected aggregates transferred by conveyor means to cargo holds. the bins are readied to again receive collected aggregates. The bins are made airtight, and valves V1 and V2 (FIG. 6) are opened, valves V3and V4 are closed, and the aft receiver bins emptied in a similar manner as described with respect to the forward receiver bins.

During receiver bin unloading operations aggregates which are deposited on first

longitudinal conveyors

110 and 110 are water laden. in order to aid' in dewatering the aggregates to prevent clogging andto facilitate conveying, transfer and storage, there isprovided heat transfer means which may conveniently be within the housing 130.

Each of the heat exchangers has a respective exhaust stack 171 and 171 which extends to a point above the bridge 173. In a similar manner, the aft portion of the conveyors 110 and 110' have associated therewith heat exchangers of which one. 175, is shown in phantom and which include respective exhaust stacks 176 and 176' also at a height above the level of bridge 173.

The heat utilized toaid in dewatering the collected aggregates may be derived from the waste heat of a prime mover. FIG. 7 illustrates one such arrangement which may be utilized. Compressed air for the air lift system is supplied via pipe 63 (also shown in FIGS. 4 and 5) by means of a compressor 180 which in turn is driven by a prime mover such as a gas turbine 182 through suitable coupling means 183. The gas tu'rbine exhaust 185 is directed via a valving arrangement 187 to a selected

pair

170, or 175, of heat exchangers. The

' heat exchangers may be fabricated such that the exhaust gases do not come in actual contact with the collected aggregates but are merely in 7 heat transfer relationship therewith. Although the present invention has been described with a certain degree of particularity, it should be understood that the present disclosure has been made by way of example and that modifications and variations of the present invention are made possible in light of the above teachings.

We claim:

1. A surface vesselfora deep underwater mining system utilizing a bottom material collector, conduit means extending from the vessel to the collector, and a gas lift system for the conduit for raising collected material, comprising:

a. a closed receiver means having an outlet aperture;

b. said conduit means being communicative with said receiver means for deposit of collected material, water and gas from said gas lift system, therein;

c. discharge means communicative with said receiver means at said outlet aperture and including a discharge aperture below the surface of the water containing said vessel, for exhausting gas from said. receiver means; and

d. said discharge means initially containing a column of water which is displaced by said exhausting gas to create a back pressure at said receiver means. I Apparatus according to claim 1 wherein:

. the receiver means includes at least one receiver bin having sidewall portions, at least one of said sidewall portions including a first aperture above the water level in the receiver means;

the discharge means is communicative with said receiver bin by means of said first aperture; and

c. the discharge aperture ofthe discharge means being vertically displaced from said first aperture.

3. Apparatus according to claim 2 which includes first grill means for the first aperture for preventing collected material above a certain size from entering the discharge means.

4. Apparatus according to claim 2 which includes discharge grill means for the discharge aperture for breaking up the gas exhausting through the discharge means into a plurality of bubbles. I

5. Apparatus according to claim 2 wherein:

a. the vessel includes a deck and bottom;

b. the discharge means is a gas vent trunk extending from said deck to said bottom; and including c. a substantially airtight closure for said gas vent trunk at said deck. 7

6. Apparatus according to claim 5 which includes valve means disposed with the gas vent trunk for varying the size of the discharge passageway of said gas vent trunk.

7. Apparatus according to claim 6 wherein the valve means is operable from the deck.

8. Apparatus according to claim 7 wherein the closure is removable for servicing the valve means.

9. Apparatus according to claim 1 wherein:

a. the vessel includes starboard and port sides and a fore and aft portion; and

b. the receiver means includes at least first and second receiver bins, one on the starboard side and the other on the port side of the vessel.

10. Apparatus according to claim 9 which includes:

a. third and fourth receiver bins;

b. said third receiver bin being disposed aft of the first receiver bin; and

c. said fourth receiver bin being disposed aft of the second receiver bin.

11. Apparatus according to claim 10 which includes means for selectively connecting the conduit means with the first and second receiver bins only and thereafter with the third and fourth receiver bins only.

12. Apparatus according to claim 9 wherein:

a. the vessel includes a deck and at least a hold for storage of collected material; and which includes b. first longitudinal conveyor means;

c. means for transferring collected material from the receiver bins to said first longitudinal conveyor means;

d. transverse conveyor means for receipt of material from said first longitudinal conveyor means; and

e. second logitudinal conveyor means for transferring material from said transverse conveyor means to said hold.

13. Apparatus according to claim l2 wherein:

a. the second longitudinal conveyor means includes first, second and third conveyors which pass over the hold; and which includes b. transfer means for selectively transferring material from the transverse conveyor means to selected first, second or third said conveyors.

14. Apparatus according to claim 12 which includes housing means covering all the conveyor means for protection against the elements. 7

15. Apparatus according to claim 1 wherein:

a. The vessel includes at least a hold for storage of collected material; and which includes b. transfer means for transferring collected material from the receiver means to said hold;

c. a source of-heat; and

d. heat transfer means for transferring heat from said source to aid in drying of material on said transfer means.

16. Apparatus according to claim 15 wherein:

a. the gas lift system includes a compressor for supplying gas under pressure; and which includes b. a prime mover for driving said compressor, said prime mover having an exhaust of hot gases;

c. heat exchange means in operatively disposed relationship with the transfer means; and

d. means for conducting said hot gases to said heat exchange means.

17. In a material lift system including a fluid filled conduit means extending between first and second vertically spaced points for conveying collected material, and a gas lift system for introducing gas under pressure into the conduit means for raising collected material, the combination comprising:

a. closed receiver means at said first point for receipt of collected material;

b. said conduit means being communicative with said receiver means for deposit of collected material and gas from said gas lift system;

c. gas discharge means communicative with said receiver means for discharge ofgas; and

d. said gas discharge means disposed to discharge gas against a liquid pressure to create a back pressure within said receiver means of a magnitude to simulate the pressure a point, within said fluid filled conduit, between said first and second vertically spaced points.