Innovative Deep Ocean Mining Concept based on Flexible Riser and Self-propelled Mining Machines

Transcription

1 Iovative Deep Ocea Miig Cocept based o Flexible iser ad Self-propelled Miig Machies. Hadschuh, H. Grebe, J. Pathel, E. Schulte, B. Wezlaski, W. Scharz Istitut für Kostruktio Siege (IKS), Uiversität Siege, Fachbereich Maschietechik, D-5768 Siege, Germay. (.ui-siege.de) M. A. Atmaad,. Jeyamai, M. Shajaha,. Deepak, M. avidra Natioal Istitute of Ocea Techology, NIOT Campus, Velachery-Tambaram Mai oad, Palikaraai, 6132 Cheai (Madras), Idia. Abstract: This paper presets the cocept of a itegrated miig system based o self-propelled, track pad mouted cralers equipped each ith a collector, a crusher ad a pumpig uit, a umbilical cosistig of a flexible hose ad a cable ith associated buoyacy packages, a mother statio ith the eeded utility systems (electricity), support systems (propulsio, positio cotrol, slurry hadlig ad craler hadlig) ad cotrol systems (trasducers, actuators, computer commuicatio, video surveillace). Keyords: magaese odule miig, craler, flexible riser, umbilical IKS, amogst various other research istitutes ad compaies, developed from the eighties o a system, hich is expected to miimise the problems listed above, except for the legal aspects o hich the desig ca have o ifluece. This developmet resulted i hat e call today the flexible riser cocept ith self-propelled miig machies feedig a mother statio, as sho i Fig. 1. Ulike a miig system developed by Ocea Mierals Compay (OMCO) ad tested by Lockheed Marti (Wellig, 1996), here the mier delivers the odules ito a buffer through a flexible riser, to pump it to the surface through a rigid pipe strig, the cocept developed by IKS uses a flexible riser from the miig machie to the surface of the sea. Cocept: To uderstad the cocept of the flexible riser miig system ad its advatages, it is helpful to look back at the miig cocepts developed i the past ad their drabacks. The most elaborated ad advaced cocept of the 7ies cosisted of a drillig ship, a approximately 5 m vertical steel pipe ad a toed collector. After various theoretical aalysis (e.g. Köhe, 1974, Köhe 1976, Chug 1981) this system as realised by a group of compaies uder the ame of Ocea Maagemet Icorporated (OMI), ad is sho schematically i fig. 1. The cosidered output as 3 millio tos of et odules per year. Slurry Pump 1 m Steel Pipe This system, though proved to be techically feasible, had the folloig disadvatages ad their combiatio lead to the ed of further implemetatio: Toed Collector 52 m - Large ivestmet capital requiremets. - Uforeseeable risks (legal, fiacial ad techical) - Little flexibility, critical productio bottleecks ad - associated possible dotimes - Iaccurate cotrol of collector path. Fig. 1: igid Steel Pipe System versus self propelled Miig Machie ith flexible iser (Ecker, 1978, Scharz, 1999) The system is to be modular ith high extesio potetial. Each mother statio is to receive the slurry stream of up to 4 craler mouted miig machies, ith a capacity of 5 t et odules per year from each craler (i.e. 2 t year per mother statio). The OMS-1-MT-14 Page: 1 of 9

2 muddy ater is the separated ad discharged back ito the ocea i depths such as to miimise the ecological impact. From the mother statio the odules are shipped to the metallurgical processig plat. Depedig o the ecessary capacity to ru such a processig plat i competitio ith covetioal plats, the umber of mother statios is to be defied. Each of the miig machies is equipped ith a device to loose ad to pick-up the odules (collector), crush ad pump the odules through a flexible riser to the surface. The remote cotrolled, craler-based miig machie ill be able to harvest a delimited area ad able to avoid obstacles. Compared to the rigid steel pipe system, the expected advatages are umerous ad outlied belo. The small scale ad the modularity of the system allo iitial ivestmets costs to be oly a fractio of those estimated for the OMI system (Flipse 1981, Adres 1982) hich as tested i the late seveties (The ecoomic aspects of a flexible riser system are curretly ivestigated i a project ra by IKS). Also, the techical risks are miimised by the described approach. If oe starts for example ith a mother statio fed by oe craler oly, the cocept ca be tested, operatio ad maiteace data ca be gathered ad the dra coclusios used to improve ad simplify the ext cralers for this same mother statio. The approach also reduces the techical ad fiacial risks durig operatio, he compared to the steel pipe system, here a breakdo ould stop the etire operatio. The flexible modular system offers the possibility of a almost cotiuous miig operatio ith oly partially reduced output should oe of the cralers or mother statios. The amout of bottleecks is strogly reduced. I additio to breakdos, bad eather situatio ca require the stop of operatios. I the preseted modular system, the evisaged solutio ould be to leave the miig machies o the seabed ad to discoect them from the mother statios, leavig the umbilical attached to a buoy. Last but ot least, the miig field ca be harvested ith a high efficiecy as the craler path ca be cotrolled accurately to allo coverage of every mieable spot ithi the selected area. To give a idea of the order of magitude, the cateary shape of the umbilical gives each craler eough freedom to move up to approximately 1 m from the mother statio ito each directio, i.e. all cralers feedig the same mother statio cover a area of 4 km 2. For a average odule abudace = 7.5 kg/m 2 (of hich a total of 7%, i.e. 5 kg/m 2 is assumed to be collected), this meas that the mother statio ould have to be moved by 2 km approximately every 1 to 1.5 moths. From the mother statio, the odules ould be coveyed ito a ocea goig barge that ould be picked up ad brought to shore by a ocea goig tug. Each mother statio ould be coected to such a barge able to store eough odules to cover at least the time spa it takes to get to shore, uload ad come back. With several mother statios orkig ithi oe area, the barges may be combied to form a barge trai ad to be pulled together by oly oe larger tug or, alteratively, a lighter-aboard-ship-carrier (lash-carrier) type of cofiguratio usig smaller barges (lighters) ca be cosidered. I the past, ecoomical models have bee developed based o a output either 1.5 millio t or 3 millio t output (Flipse 1981, Adres 1982). To reach semi-commercial magitudes a output of approximately 1 millio et tos per year, i.e. 4-5 platforms are cosidered. With gaiig experiece, it is expected that larger cralers ith higher collectig ad pumpig capacities ill be developed so that a output of 1 millio t of et odules per year per mother statio is targeted. As it appears today, the limitig factor ill be the 1 m maximum distace from the mother statio. This is a summary of the lie of thought regardig the cocept of self propelled miig machies ith flexible risers. The ext sectios ill describe i more detail the compoets of such systems util the poit ere the odules reach the surface of the sea, hile trasportatio ad processig ill ot be addressed here. Nodule collectio Magaese odules are maily foud i ater depths of 4 to 6 m, sometimes more. They have various shapes ad are typically embedded i the semi-liquid top-layer of the deep sea soil. To pick up these odules, several devices have bee developed i the past ad are still beig developed today (Thetis, 1992, Scharz, 1999). Some of these devices have bee tested i the real deep sea, some oly o simulated deep sea soils o the laboratory scale ad some have ot yet bee tested at all. Whatever device is chose to be mouted o the self propelled miig machie ith flexible riser, IKS has idetified the folloig requiremets. - Highest collectig efficiecy at velocities aroud.2 m/s - High collectio rate of all odules ith a diameter betee 17 mm ad 1 m (i.e. 7% or more of all the odules i the field). - Lo impact o the soil - Separatio of odules from the cloggig soil particles ad precleaig from sedimets - Coveyig of the odules to a crusher. - Crushig of odules to a diameter of 3 mm or less. - Lo eergy cosumptio - High reliability The folloig existig desigs ill be preseted ad aalysed regardig the above metioed requiremets. Cocepts for toed collectors ill ot be discussed here as they typically do ot fit i ith self propelled miig machies. At last a cocept developed by IKS ill shortly be preseted ad subjected to discussio. Magetic collectig methods: Magaese odules do react to magetic forces. Hoever, due the magitude of magetic fields required ad the associated electric poer demad, this cocept as abadoed i the very early stages (Scharz 1999). Fluidic ad fluidic-mechaical collectig methods Fig 2: Collector Movemet Nozzle v Guide Plate Groud Schematic Priciple of TAM Collector (left) ad VWS collector (right) OMS-1-MT-14 Page: 2 of 9

3 A purely fluidic collector type has bee developed recetly ad tested i the real deep sea i 1997 by the Japaese Techology esearch Associatio of Ocea Mieral esources Miig System (TAM), see fig 2. Based o the Coada Nozzle effect, this collector as actually a toed collector. Its priciple hoever is basically suitable to be adapted to a self propelled miig machie. While the collectig efficiecy reached as satisfactory values as 87% for odules of 3 mm ad less, the amout of uated soil sedimets that ere coveyed simultaeously as very high (Tsurusaki, 1999). The requiremet of lo eergy cosumptio ad of little impact oto the soil as therefore ot met as expected I the mid eighties, the Germas developed a hybrid collector hich uses a fluidic method to loose the odules ad a mechaical belt coveyor to trasport them. The schematic diagram is sho i Fig. 2. Fig. 4: Mechaical collector desiged by Preussag ad tested by IMB Fig. 3: IKS craler ith hybrid-mechaical VWS collector at Haover fair i 1992 Pick-up Device v Coveyor Belt This collector as ever tested i the deep sea, oly o simulated soil at the Versuchsastalt für Wasserbau ud Schiffbau (VWS) i Berli (BMFT / Thetis 1993). There also, the fidigs ere a excessively high eergy cosumptio ad heavy impact o the simulated deep sea soil. It as preseted to the public mouted o the already existig IKS craler durig the idustrial fair i Haover i 1992, fig. 3. Movig Comb Base Comb Mechaical collectig methods Oe of the first collectors used o a large scale test (the OMI Test) as of the mechaical type ad as ufortuately lost durig recovery. Aalysis of the advatages is therefore difficult. A similar collector as hoever tested later i the test basi of the Istitut für Maschie im Baubetrieb (IMB) of the Uiversity of Karlsruhe, Germay, o simulated deep see soil. It shoed a bedig of the ties at higher speeds (,5 m/s) ad cloggig ith the soil imitate, fig. 4 (BMFT/Scharz, 1987). IKS has compiled the above listed disadvatages ad developed a collector type that is expected to miimise them, fig. 5. The frame of the pick-up device is coected to the loer coveyor drum shaft. It is mouted o a skid hich maitais it o a certai distace from the groud. The frame cosists maily of profiled sheet metal, assembled to a comb-like grate structure (base-comb). The tooth-like frot of the frame udercuts the sea bed ad smoothly dislocates the magaese odules. Fig. 5: Cocept of a mechaical odule collector (IKS, 1999) Additioally, a mobile, mechaically drive comb-like structure moves ithi the gaps of the frame structure. This ay, the odules are lifted ad moved toards the belt coveyor. I order to clea the odules before they are discharged oto the coveyor, a vibrator is mouted o the basic frame. Both comb structures clea each other from sedimet residues through their relative motio. From the pick-up or loader device the odules are the lifted by the steep iclie belt coveyor ad trasported to a crusher before eterig the pisto pump ilet. Trasport of odules through the flexible iser The odules delivered from the crusher are fed ito a positive displacemet pump located o the self-propelled miig machie movig over the soft seabed. The poer requiremets to pump the OMS-1-MT-14 Page: 3 of 9

4 Poer P i kw ad Pressure p i bar crushed odules alog ith ater as to-phase flo through a flexible hose to the mother statio ad the poer cosumptio to move the miig machie o the seabed are calculated as follos: Poer cosumptio ad liftig parameters For realisatio of the miig system it is essetial to determie the poer cosumptio P to pump the odules to the surface. The poer required ca be expressed by the total pressure loss p ad the total flo rate V P p V. (1) The total flo rate of the to-phase mixture ca be determied accordig to the ier cross sectio A i of the hose, the velocity of the odules v ad the velocity of the trasport ater v : V Ai c v (1c ) v W V V. (2) The total flo rate is the sum of the odule flo rate rate of the trasport medium V accordig to Buhrke (1989) is give as: c V V ad the flo. The trasport cocetratio c V. (3) v Ai V For a give odule flo rate V ad a ier hose cross sectio A i the trasport cocetratio ca be adjusted accordig to the upard velocity of the odules v. This velocity depeds o the velocity of the trasfer medium v ad the sik velocity v s of the odules (Buhrke 1989). Ad is calculated as v v vs. The sik velocity of odules (idealised as spherical grais) ith a diameter of D ca be obtaied from equatio (4), takig ito accout the drag coefficiet, the desity of odules ad the desity of ater accordig to Brauer (1971) ad others as v s 4 D g 3 To realise a hydraulic trasport the trasport velocity must be higher tha the sik velocity. Therefore the velocity of the trasfer medium is chose as a multiple of the sik velocity: v vs. Accordig to Brauer (1971) a parameter 5 is recommeded to achieve the miimum required trasport velocity. With a odule desity kg / m, a desity of ater 1 kg / m ad grai diameters up to 3 mm the required trasport velocity ill be i a rage betee m/s. The pressure hich has to be provided from the pump to trasfer the odules is a result of geodetic height pgeo ad frictio losses i the hose : pdy p geo dy. (4) p p. (5) I order to obtai a estimatio for the pressure, a purely vertical trasfer is assumed. The trasfer height i ater is approximately that of the depth of ater h. Aother fe meters (say 1 m) as the distace betee the mother statio s deck ad the ater surface are added ad * give the total trasfer height of h (ater colum plus height i air) p geo ( 1 c c g h * g h ) (6) The dyamic pressure drop is also calculated uder the assumptio of a vertical trasfer i a hose ith a ier diameter of Di ad the total hose legth L. 2 p L c d 2 ( 1 c dy ) v * v 2D 2D i i The calculatio of the dyamic pressure drop i most cases is difficult as the exact frictio coefficiet is ot ko. Here a empirical calculatio formula is take, hereby the frictio loss coefficiet is split up ito oe for the ater ad oe for the odules. The all * frictio coefficiet for odules is calculated empirically (Egelma 1979) based o the ratio of the trasfer parameters * D D i v g D i 1. 6 (7). 7 2 m. (8) m I this m is the mass flo of odules ad m the mass flo of the trasport medium. It is a empirical equatio, hich has bee derived usig the dimesio aalysis ad -theorem hich permits trasmissibility of test results o differet systems. The all frictio coefficiet of ater ca be obtaied i depedecy of the eyolds Number by the equatio of Colebrook (1938) hich formulates a uiversal resistace la for smooth hydraulic tubes ,3,4,5,6,7,8,9,1 Poer i kw Pressure i bar Trasp. Cocetr. C Hose ier diameter D i 1,,9 Fig. 6: Poer cosumptio, pump pressure ad cocetratio versus hose diameter Figure 6 shos the results of a calculatio of required poer, pump pressure ad trasport cocetratio depedig o the hose diameter. The calculatio is based o a suggested small scale miig system of approx. 5 t/a. It is proposed to use a hose of 8 mm ier diameter to achieve a trasport cocetratio of c 12% ad acceptable values for poer cosumptio ( P maximal pressure required for the pump ( p 13bar ). 155kW,8,7,6,5,4,3,2,1 Cocetratio C ) as ell as OMS-1-MT-14 Page: 4 of 9

5 For the system it is evisaged to use a positive displacemet pump, located o the self-propelled miig machie. Such pumps are available o the orld market ad may be adapted to the specific evirometal coditios of the deep sea. Shape of the hose The etire cocept is based o a cotiuous flexible riser hose. Various calculatios ad model scale tests have bee carried out (Lübbert, 1986, Freitag, 1993) for straight hoses from the miig machie o the sea floor to the surface ith some slackess oly. It became clear that such cofiguratios ould ot be practical, due to the eormous forces actig o the hose ad therefore o the ship ad especially o the miig machie itself. The reaso for these high forces is the flo agaist the hose he moved i the ater. The solutio as to modify the spatial shape of the hose i the ater colum so that oly a mior hose segmet eeds to be moved durig the miig machie operatio. 5 z x v c 1 15 Costat Curret 32 Ship Velocity Mier Velocity Outer Diameter: Ier Diameter: Legth: y v S. m / s F i kn t i s F i kn poit 32 poit 1 rea. Fx Fy Fz t i s Curret Surface v CS. 5 m/ s v M. 2 m / s Curret Seafloor v CB. 15 m/ s d a. 16 m Axial Stiffess: EA 4kN d i. 14 m Drag Coefficiet: c D 1. 4 L 596 m Added Mass coef.: c a Desity Water: 13 kg / m Desity of Mixture: 113 kg / m Fig. 7: Exemplary Calculatio of Shape for a Movig Miig Machie resistace, iertia force, pressure force, force due to mometum chage ad cosideratio of bedig. Therefore the S-shape as chose. The S-shape as ko for short coectig lies o offshore applicatios ad moorig lies. The shape is geerated by attached buoyacy material either o defied poits or distributed alog a certai legth of the umbilical. To calculate the etire hose for the miig purpose a computer program as developed (Scharz 1995; Grebe 1996) i hich the riser is replaced by a lumped mass model ith fiite hose elemets. The physical effects covered i this program are the three dimesioal o-statioary flexible riser behaviour uder cosideratio of large displacemets, drag loads from movemet of miig machie, curret ad ave effects, iertia force ad forces from the iteral flo. To geerate the S-shape to optios are possible i the mathematical model. Oe is to have a distributed buoyacy. The buoyacy parameters are the cosidered to be icluded i the elemet properties such as diameter, eight per legth, etc. The other optio is to cosider the buoyacy forces as a vertical force actig o a mass ode correspodig to a equivalet amout of buoyacy material. The last is a rough idealised mode, but is expected to be sufficiet to give first results. Further aalysis should be carried out usig fiite elemet programs for detailed aalysis. Fially Figure 7 shos a sample calculatio for the above metioed umbilical cofiguratio. The hose has ot bee desiged o ad the values used are the oes for a Aramid fabric rubber lied hose desig (Scharz 1993). The kid of hose is evisaged to realise a lighteight ad less bedig stiffess desig he compared to stadard offshore hoses. (I the example the bedig stiffess is eglected.) The fial desig has to be able to resist the omial axial tesio of aroud 7 kn ad a pressure of 15 MPa ith a adequate factor of safety. The hydrodyamic forces are calculated usig the Moriso equatio ith drag load ad iertia terms (Clauss, 1992), cosiderig the hydrodyamic mass for a circular cylider (used added mass coefficiet c a 1). Poit 1 represets the miig machie o the sea floor, poit 32 represets the ship o the surface. It is assumed that the ship s positio is fixed ad that the miig machie moves ith.2 m/s alog a give path. Additioally a surface curret of.5 m/s ad a bottom curret of.15 m/s from the same directio are overlaid. The figure shos that the forces at the miig machie (poit 1) ca be brought do to a rage hich is possible to be hadled as much from the machie size poit of vie as from the eergy required for movig, eve he cosiderig the poor tractio capacities of a soft deep sea soil. The major target i developig such a riser based miig system is to miimise the total poer cosumptio icludig pumpig ad drivig operatios. The S-shape offers a large operatio area for the miig machie. Due to the buoyacy material located i the loer sectio of the hose heave motio from the surface are absorbed ad do ot affect the miig machie much. Hoever the atural frequecies of such umbilical are close to that of the frequecies of the relevat ave spectrum (Sub Hog, 1992). Durig the desig phase care has to be take that the atural frequecies of the system are ot matchig the oes of the aves. Craler Desig A miig system ith self-propelled cralers ad flexible riser systems ould be most practicable ad efficiet (Melcher 1986, ehor 1994, Dörfler 1995). Oe of the basic compoets for the magaese odule miig system is the actual miig machie. I this chapter the desig of a self-propelled craler, developed by IKS, is itroduced ad some special coditios are cosidered The craler is used as a carrier for the collectig device ad for draggig the flexible riser. The mai structure of the actual miig machie is sho i Fig. 8. OMS-1-MT-14 Page: 5 of 9

6 equiremets ad Features of the craler The specificatios for the craler have bee orked out by IKS ad are summarised here. The craler chassis has to craler tracks ithout slopig ilet ad directio is cotrolled by slip steerig. The mai frame of the chassis is completely rigid. The chai heels are each coected to the mai frame through the upper rocker to allo some degree of tiltig. A set of 4 rollers is mouted to each loer rocker. To loer rockers are coected to oe upper rocker to form a freely tiltable lever suspesio arragemet. The etire system is ciematically udefied, but ithi certai boudaries the ueveess of the soil ca be compesated by the rocker system. To support the upper segmet of the track, to rollers are istalled o each side of the chassis. craler track roller maiframe drive uit Fig. 8: Cocept model of the magaese odule miig machie (Wezlaski 2) tesio device loer rocker upper rocker sprocket Evirometal coditios For the desig of the deep sea miig machie some specific evirometal coditios i deep sea ad o lad have to be take ito accout (Wezlaski 1999, 2, Melcher 1986, ehor 1994): The craler ill operate i sea ater depths of to 6 m, hich meas it has to stad ambiet pressures ragig from 1 bar to 6 bars. The ambiet temperatures amout from approximately C i the deep sea ad durig hot eather o lad up to 5 C air temperature he directly exposed to the su. With respect to the corrosive effects of sea ater it has to be oticed, that the salt cocetratio is approximately 3.5% ad the oxyge cocetratio varies betee 6 ad 1 ppm. The ph-value varies betee 7 ad 8. While craler tests o lad ill take place oly o eve sady groud, for deep sea operatios the vehicle ill have to move o soft soils ith partially hard obstacles up to 15 mm high, small hills ad ditches or treches similar to river beds. While beig lauched, the craler is exposed to high stresses caused by ave actio ad ship movemet. To avoid damages the craler has to be desiged to stad a sea state of 5 durig lauchig. Due to the ufavourable characteristics of deep sea soil regardig its trafficability, the tractio ad mobility of the craler are strogly limited. Accordig to Melcher (1986) ad ehor (1994) the shear stregth max rages betee ad 7.4 kpa ad the ormal soil is covered by a semi-liquid layer of up to 1 cm. For plaig the e miig machie, the limit of trafficability is set for a shear stregth value of max = 2.5 kpa. At this limit oly very lo tractio potetial is expected. Wezlaski (21) shos that, amely due to deep sikage of the vehicle, high exteral drivig resistaces build up, so that the useable tractio force is further decreased. The bearig capacity at the limit of trafficability is calculated accordig to the approach of Terzaghi (1961) ad it has a value of 14 kpa (Wezlaski 1999). To guaratee the craler s mobility, the groud pressure σ C applied by the craler must ot exceed the soil bearig capacity, the vehicle therefore has to be build as light as possible Fig. 9: a desig of the craler chassis (Wezlaski 2) To achieve a smooth ruig of the trackig elemets, all rollers are desiged slightly spherically ad tapered at both eds, so that they fit tightly ito the guidig elemets of the track. The craler tracks cosist of profiled ylo track pads, hich are coected by to parallel drive lik chais made of light metal. I Fig. 9 the most importat features ad dimesios of the craler chassis are represeted. The required drive poer is geerated by hydrostatic motors, the poer itself beig trasmitted to the sprockets through permaet ratio gearboxes. The complete drive uits (motor ad gearbox) are coected to the double sprockets at the rear of the craler. The positive poer trasmissio betee drive ad craler track is doe through itervetio of the drive sprockets ad the chai sleeves. The drive cocept is sho i Fig. 1. The preferred motio directio is forard, but the vehicle is desiged to be able to move backards OMS-1-MT-14 Page: 6 of 9

7 also. For compesatio of rear sikage due to slip, the cetre of gravity of the vehicle is slightly moved toards to the frot. The mai frame, the rockers ad all other supportig parts are made out of seaater-resistat alumiium alloy AlMgSi, titaium ad stailess steel. Especially the coectig elemets, the smaller compoets ad highly stressed elemets are out of stailess steel. To avoid galvaic corrosio betee the differet materials suitable measures are to be take. Wog (1993). Here the shear stress-shear displacemet relatio for soft soil ith a maximum shear stress ad folloig smooth decrease to a residual shear stregth is regarded. The ier frictio of the deep sea soil is less ad therefore eglected. The cohesio correspods to the shear stregth of the soil. The relatio betee maximum shear stregth max ad residual shear stregth res is assumed ith K =.5 (Bode 1991). The folloig, simplified formula is therefore used: sl sl 2sL K K 1 1 W K e W W K W K W F T A max K 1 e e e e s L (9) K e 1 2 s L Fig. 11 shos the results of the calculatio for deep sea soil ith a shear deformatio of K W = 7 mm at a maximum shear stress of max = 2.5 kpa ad ith a residual shear stregth of res = 1.2 kpa. tractio force FT i kn slip s i % Fig. 1: Arragemet of craler track, sprockets ad rollers As to the choice of bearigs, maily slidig bearigs are used. For highly stressed bearigs, sealed ati-frictio bearigs ith lubricat storage are the better alterative. For limited oscillatig motios ad mior requiremets regardig the guidig accuracy, steel-rubber elemets are relied upo. All compoets of the craler chassis such as maiframe, rockers, bearigs, drive uits, rollers, tracks etc. are to be dimesioed for a durability of 1 hours meatime betee maiteace (MTBM) ith regard to stress, corrosio ad reliability. Fig. 11: Tractio force of the deep sea craler i relatio to slip Accordig to Fig. 11 the maximum tractio force is estimated to F T,max = 17.5 kn at a optimum slip of approximately s opt = 4%. The limit of permissible slip should ot be higher tha s max = 1%, as the tractio ill rapidly decrease at values higher tha the optimum slip ad the mobility of the vehicle is the edagered. To realise drivig performaces as metioed above, a drivig poer of 2x2 kw ith a maximum torque of 15.7 knm at each drive sprocket at a velocity of.3 m/s are required. Dimesios ad techical Data of the Craler The mai dimesios of the miig machie are restricted by the hadlig ad lauchig facilities o board of the mother statio. The mai dimesios cosidered ca be see i Fig. 9. With a track gauge of W G = 2.2 m the steerig ratio (L/W G ) amouts to λ = 1.45, hich is i a satisfactory rage for the maoeuvrability of tracked vehicles (Mehr-hof/Hackbarth 1985, Wog 1993). Each track cosists of 34 track pads. Each track is dimesioed for a pre-stress force of 4 kn ad a maximum chai tesio force of 6 kn. I order ot to exceed the limit of soil bearig capacity of σ max = 14 kpa, the maximum total eight of the complete miig machie is set to 85 kn i ater (1 kn i air), so that the average static soil pressure of the craler i ater comes to σ = 1.3 kpa. The maximum velocity durig trasit operatios is.5 m/s ad velocity durig collectig operatios is.2 m/s. With cosideratio of slip the maximum tractio force ca be estimated accordig to the approach of Ship / odule hadlig The mother statio for the etire miig system ca be either a ship, a barge or a platform. It has to meet ith differet requiremets. The mother statio has to provide eough deck area for istallatio, repair orks, dry-tests for the miig machies as ell as for the supportig craes to hadle the miig machies or their compoets. Additioally, the space for a lauchig system ad for hose ad cable iches is ecessary. Also, cotrol rooms ad rooms for the orkshops icludig all ecessary tools ad ma poer are required. Furthermore, facilities to allo bukerig of odules as ell as a slurry hadlig ad ater draiig system cosistig of a pipe system oboard, a separator, a optioal filterig system ad a discharge system for the muddy ater to deeper ater regios eed to be istalled o the mother statio. As to the utilities, the mother statio has to provide eough electrical poer for all four miig systems hich is expected be as much as 2.2 MW, the poer for propulsio, positioig ad ruig the mother OMS-1-MT-14 Page: 7 of 9

8 statio itself ot beig icluded. To allo proper operatig of the miig machies, the mother statio has to be kept i orieted ad i positio ithi a required accuracy of 5 metres hich ca be achieved for example ith a Dyamic Positioig System. At last the requiremets for accommodatig the staff (autical, techical, scietific, etc.) eed to be met ith, as ell as the requiremets for safety features ad commuicatio systems, etc. used. The mai cotrol system ith redudat compoets is istalled o the mother statio (Schulte 21). All fuctios of the miig machie ca be cotrolled i maual modus by joysticks or i automatic modus through a computer routie. For this purpose, the miig machie itself is equipped ith a cotrol system hich is istalled i various pressure proof housigs. All sesors ad actuators such as acoustic ad icremetal speed measuremet uits, pressure sesors, headig idicatio, hydraulic valves, etc. as ell as the uderater cameras ad lights hich are istalled o the miig machie ill be cotrolled by this system. The commuicatio betee the mai cotrol system ad the craler system ill be realised through fibre optics iside the cable. Oe possibility for this commuicatio is via a etork based o TCP/IP. A example for a suitable softare package for the miig system cosists of a process visualisatio softare i the cotrol room, a cotrol softare for developmet ad implemetatio of the mai cotrol program ad the operatig systems of the craler computer ad the cotrol computers. Such a cotrol system is described by Schulte (21). The mai cotrol program should have a predefied structure (Programmable Logic Cotroller - PLC accordig to IEC1131) ith various features for secure programmig ad olie debuggig. Fig. 12 Lauchig device for OV Literature Adres, BV, Flipse, JE, ad Bro, FC (1982) The Ecoomic Viability of a Four-Metal Pioeer Deep Ocea Miig Veture Texas A&M Uiversity, 21 p. Brauer, H, (1971) Grudlage der Eiphase- ud Mehrphaseströmuge, Verlag Sauerläder, Arau ud Frakfurt am Mai, 955 p. Bode, O (1991). "Simulatio der Fahrt vo aupefahrerke," Ph.D. Thesis of the Uiversity of Haover, 134 p. Craler hadlig ad operatio A lauchig system has to be used to loer the miig machie to the seabed. Oe mai compoet of this lauchig system is a hadlig device to brig out the miig machie ito the ater ad to avoid damages due to hittig agaist the mother statio structures. This ca be a tiltable A-frame ith support structure, a crae or a fork lifter. Oe example of a supplier for such equipmet is sho i fig. 12 (ODIM, 21). Durig lauchig the miig machie ill be hadled by a umbilical, hich cosists of a cable ad a hose. The cable is the mai part to carry the load. Further it is used to trasmit the electrical poer at voltages of 6 to 1 kv. The data trasmissio for the cotrol of the miig machie is realised via fibre optics hich are also icluded i the cable. The hose ill be of the flexible type ith a ier rubber liig. To form a sigle uit out of cable ad hose, it is eeded to attach the hose to the cable at certai itervals or cotiuously over the etire legth. This process has to be automated. To get the required S-shape it is also ecessary to attach floats to the umbilical hich ill form the shape after the miig machie touches the seabed. To operate the miig machie, a computer system i coectio ith a stadard idustrial field bus system for data acquisitio ad cotrol is Buhrke, H, Kecke, HJ, ichter, H (1989). Strömugsförderer, Verlag Vieeg & Soh, Brauscheig, 368 p. Chug, JS, Brik, AW (1981) Automatic Positio Cotrol of a 3, tos Ship durig Ocea Miig Operatios, 13 th Aual OTC, Housto, pp Clauss, G, Lehma, E, Östergaard, C (1992): Offshore Structures, Volume 1, Spriger-Verlag, Lodo Berli Heidelberg. 342 p. Colebrook, C.F. (1938) Turbulet flo i pipes, ith particular referece to the trasitio regio betee the smooth ad rough pipe las, Joural for Istitute of Civil egieerig, 11, Lodo. Dörfler, G (1995). Utersuchuge der Fahrerk-Bode-Iteraktio zur Gestaltug vo aupefahrzeuge für die Befahrug eicher Tiefseeböde, publicatios of Istitut für Maschieese im Baubetrieb of Uiversity of Karlsruhe, series F / paper 43, 312 p. Ecker, K, (probably 1978). Submersible motor pumps for Deep-Sea- Miig KSB Documetatio, Frakethal, 6 p. Egelma, H (1979). Eiführug i die vertikale hydraulische Förderug grober Feststoffe, Marie ohstoffgeiug Bad 1, Verlag Glückauf, Esse OMS-1-MT-14 Page: 8 of 9

9 Flipse, JE (1981). The ecoomic viability of deep ocea miig Texas A&M Uiversity, 57 p. Freitag, W (1993) Teoretische ud experimetelle Utersuchuge zum Verhalte lager Tiefseesträge PhD Thesis, Uiversity of Siege, Shaker Verlag Aache, 141 p. Grebe H (1996). Magaese Nodule Miig from Deep Sea. Iteratioal Deep seabed miig Semiar, Beijig, pp B43-B52. Köhe M (1974) Lieare Optimale egelug elastischer Systeme, Ph.D. Thesis, Uiversity of Stuttgart, 17 p. Köhe M (1976) Ivestigatio of the Dyamic Behavior of Elastic Pipes für the Hydraulic Liftig of Deep Sea Mierals Iter Ocea 76, Düsseldorf, pp Köhe M (1976) Simulatio ad optimal cotrol of haulig pipes i Ocea Miig Systems, 2 d IFAC Symposium o Automatio i Miig, Mieral ad Metal Processig, Johaesburg, 9 p. Lübbert, M (1989): Experimetelle Modellierug flexibler dyamisch beegter Verbidugsleituge zische selbstfahrede Tiefseemaschie ud ihre Mutterschiffe, Ph.D. Thesis, Uiversity of Siege, 124 p. Thetis Techology GmbH (1992) The Evirometal Impact of Deep Sea Miig, Sectio III, Miig, Haover, 283p. Thetis Techology GmbH (1993) Magakollekollektor Detailplaug für die Tiefsee, Schlußbericht 1 über das BMFT Forschugsvorhabe MTK 538, Haover, 136p. Tsurusaki K (1999) Fudametal Study for Developmet of collector Sub-System ad its future eeded Techology ISA Kigsto- Jamaica, 14 p. Wezlaski, B (1999). Aalyse vo Kostruktiosmerkmale vo aupefahrerke ud Erstellug eies Lastehefts für de Neubau eies Tiefsee-aupefahrerks, Diplomarbeite-Agetur Björ Bedey, 198 p. Wezlaski, B (2). System Specificatios, equiremets ad Prelimiary Desig of Craler Chassis, Iteral eport of Istitut für Kostruktio, Uiversity of Siege, 36 p. Wezlaski, B (21). Betrachtuge zur Traffikabilität eies Tiefsee-aupefahrzeugs im Zusammehag mit Traktio ud äußere Fahriderstäde Iteral eport of Istitut für Kostruktio, Uiversity of Siege, 32 p. Wog, J Y (1993). Theory of Groud Vehicles, Joh Wiley & Sos, Ic., 2d Editio, 435 p. Mehrhof W.; Hackbarth E. M. (1985). Fahrmechaik der Kettefahrzeuge, Leuchtturm-Verlag, 2d Editio, 48 p. Melcher, P (1986). Utersuchuge über das Befahre des Tiefseebodes mit aktive Magakollekollektore, Ph.D. Thesis, Uiversity of Siege, 175 p. ODIM (21) ODIM AS Advaced Subsea Hadlig Solutios, ODIM AS, Offshore Sectio, 663 Hjrugavag, Noray ehor, I (1994). Eticklug eies Tiefseeraupefahrzeugs ud Utersuchug seier iere Fahriderstäde, Shaker Verlag, 196p. Schulte E. et al. (21) Istrumetatio of a Sad Miig System for Shallo Water), proposed for ISOPE 21 Symposium, Szczeci, 7p. Scharz, W, (1987). Kompoeteerprobug für Magakolle Geiugssysteme Abschlussbericht über das BMFT- Forschugsvorhabe MTK 355 DO, Siege, 99 p. Scharz W; Freitag W, Grebe H; Hoffma E-O (1993): Utersuchuge zum dyamische Verhalte flexibler Verbidugsleituge zische Tiefseemaschie ud ihre Mutterschiffe Abschlußbericht DFG Sch 339/3-1, Siege,.111 p. Scharz, W; Grebe, H; Hoffma, E-O (1995): Utersuchuge zum dyamische Verhalte flexibler Verbidugsleituge zische Tiefseemaschie ud ihre Mutterschiffe Abschlußbericht DFG Sch 339/3-2, Siege,.82 p. Scharz, W, Grebe, H, (1999). Workshop o Proposed Techologies for Deep Seabed Miig of Polymetallic Nodules - Kigsto/Jamaica 1999, Siege, 48 p. Sub Hog (1992) Dreidimesioale ichtlieare statische ud dyamische Aalyse vo flexible ohrleituge im Seegag. PH.D. Thesis, WTH Aache. 118 p. Terzaghi, K (1954). "Theoretische Bodemechaik," Spriger-Verlag, 55 p. OMS-1-MT-14 Page: 9 of 9