Special Issue
Mining System of Manganese Nodule in the Deep Sea
Integrated
Studies on Lifting of Manganese Nodules by Air-Lift Pump
Takayuki SAITO (Ocean Mechanics Div., Geo-technology Dept., NIRE)
Takeo KAJISHIMA (Osaka University)
Abstract
National Institute for Resources and Environment has been carrying out a basic study of a lifting system of manganese nodule. The objective of this paper is to summarize results on vertical transportation of manganese by a large-scale air-lift pump.
First, the authors discuss procedure and scheme to design a large-scale air-lift pump for large particles such as manganese nodule. Second, experimental results on pump performance of 200m air-lift pump (151mm in pipe diameter and 212.6m in pipe length), which is designed on the basis of the procedure developed by NIRE, are described. Analytical results are compared with the experimental results to find that the procedure and the scheme are reasonable. Third, similarity of air-lift pump characteristics such as flow pattern, static pressure and hold-up will be discussed. Finally, numerical scheme to simulate unsteady pump characteristics of large-scale air-lift pump is proposed.
Key words : Manganese nodule, Air-lift pump, lifted water volume, lifted ore volume, pump efficiency, non-dimensional analysis
(Language:Japanese)
Technical Report
Fundamental study of design parameters for a manganese nodule collector
Tetsuo YAMAZAKI (Ocean Mechanics Div., Geotechnology Dept.)
Katsuya TSURUSAKI (Japan Environmental Management Assoc. for Industry)
Keiji HANDA (International Research Cooperation Office
Yasuo TOMISHIMA (Rock Mechanics Div., Geotechnology Dept.)
Abstract
Objectives of fundamental study of design parameters for manganese nodule collectors were clarification or development of the following items:
- Physical, static geotechnical, and dynamic geotechnical properties of deep-sea sediments
- Resistance acting on the collector from sediments
- Sediments recovery by the collector and its effects
- Quantitative analysis and evaluation techniques of ocean collector test
- Distribution characteristics of cobalt-rich manganese deposits
From results of the study, preliminary design parameters for nodule collectors, effective information for ocean collector tests, and quantitative analysis and evaluation techniques for such tests were induced. Preliminary conceptual design of a miner for cobalt-rich manganese deposits was also presented. Outline of the study is introduced in the paper.
Key words : Manganese nodule, Collector, Deep-sea sediment, Seamount Sediment, Cobalt-rich mangamese deposit
(Language:Japanese)
Review
Environmental study for manganese nodule development
Masa-aki TSUJI and Koh HARADA (Marine Environment Div., Environmental Assessment Dept., NIRE)
Abstract
The sediment discharge and the resedimentation of sludge occurs in deep ocean mining for manganese nodules, because the seafloor mining operation directly disturbs the abyssal bottom. This discharged sediment is subjected to advection and dispersal, and redeposited broadly on the seafloor. Such an abyssal impact and resedimentation process is predicted to bring about great changes to the ecology of abyssal benthos.
The other side, low temperatute and hight nutrients bottom water as bring with Manganese nodule development, have a large effect on environment of surface ocean.
For these reasons a baseline study concerning water quality, plankton and nutrients, bottom material and fauna and observation of bottom currents was performed as a study on the sea surface and abyssal bottom environmental impact of mining for manganese nodules. Still more, the studies concerning advection and dispersal, and the resedimentation quantity of the discharged sediment, based on the observed results of current meters, transmissometers and sediment traps deployed in the vicinity of the artificial impact experiment site, are reviewed.
This paper brings together the results of analysis concerning the characteristics of surface and bottom water quality and bottom currents at the mining area of Japan where observations were carried out for during in this project. Furthermore, the numerical simulation experiment carried out concerning the diffusion and the resedimentation process of sludge bring about seafloor disturb by means of these observed result.
Key words : manganese nodule, diffusion, numerical simulation, sedimentation, nutrients, plankton, seafloor disturb
(Language:Japanese)
Original Paper
The Research and Development of Air-Lift Pumping System for Manganese Nodule Mining
Tohru SHIMIZU, Motomitsu SUZUKI, Chiaki TOJO, Yoshiyuki SHIMIZU (Technology & Development Headquarters, Hitachi Zosen Corp.)
Keiichi NITTA (R & D and Basic Design Fept. Ship Group, Sumitomo Heavy Industries, Ltd.)
Takayuki SAITO (Ocean Mechanics Div., Geotechnology Dept., NIRE)
Abstract
The air-lift pumping system transports manganese nodules from the deep sea- bed by making use of the buoyancy force of compressed air. Stable and effective operation is important under the influence of gas, liquid and solid phases in the long lifting pipe. Experiments and simulations were conducted to evaluate the static and dynamic performance of the system and to establish a suitable control method in the practical operation.
Simulation analysis to examine application to a practical system calculates the condition of gas, liquid, and solid-phases in the lifting pipe which is divided into short segments. Mathematical models are used in each segment to estimate the volume ratio of each phase, and velocity or pressure distributions. Mathematical models of air compressor and separator are added to the program to estimate the unsteadiness of operation of the whole system.
An air-lift system experiment using 200m of vertical bore was conducted to examine the steady and unsteady lifting characteristics under the influence of air flow rate, air injection depth, and back pressure in the separator.
The air compressors, the air transportation system and the air-water-nodule separator unit were designed and manufactured for the large scale test during the last stage of the project.
Three centrifugal air compressors (145 kgf/cm2, 6.1kgf/s, 5500kw) and an air hose (1490m length, 63.5mm dia.) were connected in series for the last test. A pressure change which generates at the air injection point in the lifting pipe is simulated by two operating valves. The test was conducted to examine the pressure control system when the air-lift system starts or nodule concentration fluctuates.
Key words : air-lift system, multiphase flow, air-water-nodule separator, simulation, experiment, control system
(Language:Japanese)
Original Paper
Development of submerged pump lift equipment for manganese nodule mining system
Kazuhiko SUGIYAMA (Specific Products Development Dept., Haneda Plant, EBARA corp.)
Atsunobu OMI (Engineering Dept., Rotating Machine SystemFactory, Meidensha corp.)
Abstract
The pump lift equipment, namely a pumping system of slurry, supports a lift subsystem under research and development to feed a mining ship with collected manganese nodules. This equipment is installed on the middle of the mining pipe,between the collector on the deep seabed and the mining ship. It comprises a submersible high-head multistage centrifugal pump and a submersible high-voltage motor and mining pipe. To achieve a stable mining quantity and conveys slurry with high solid contents under high depth and dynamic conditions, it demands high efficiency, high reliability and long term service life, compact size, a clog free feature and advanced control system. Then we conducted various experiments, for example a study of two phase flow (solid-liquid mixture) characteristics, the lift strings structural characteristics and the pump characteristics, etc.
Key words : pump lift, submersible pump, submersible motor, slurry
(Language:Japanese)
Original Paper
Structural Design of A Lifting Pipe on Manganese Nodule Mining System
Masao MORIKAWA (Marine Structure LAB., Tsu Research Kabs., Engineering Research Center, NKK Corporation)
Abstract
The Agency of Industrial Science and Technology [AIST], the Ministry of International Trade and Industry [MITI], began a large-scale project entitled zshe Research and Development Project of Manganese Nodule Mining System zžin 1981. The mining system of this project consists of many subsystems. Many activities on the research and development of each subsystem have already been carried out.
One of the most important structural elements is the pipe string with its function given by the nodule transfer channel and a means of towing the seabed collector. Then, the pipe string is considered to be one of the most important of the structural elements.
The pipe strings are subjected severe static axial stresses as a result of their dead weight. In addition to this, the fluctuating axial and bending stresses are produced in the pipes due to the mining ship being motion. Under these circumstances, the pipe string should be have plenty of strength. This paper presents the concept design considerations of the lifting pipes such as the evaluation of hydrodynamic load, the procedure to predict the behavior of the pipe strings, fatigue and buckling strength, non-destructive inspection and other relevant and important aspects.
Key words : Slender marine structures, Deep-sea development, Dynamic response, Pipe strings, Fatigue strength and Simulation analysis
(Language:Japanese)
Original Paper
Development of a Manganese Nodule Collector
Kazuo SANO (Sumitomo Metal Mining Co., Ltd., Mineral Resources Division)
Abstract
Manganese nodule collection sub-systems have a very important position in manganese nodule mining systems, namely at the most upstream part of the system.
The character and function required of the collector are as follows;
- After soft landing in a stable condition on the sea floor, the collector should be able to be driven smoothly on the very soft sediments of red clay.
- The Collector should sweep the manganese nodule, half buried in the sedimentary clay and take them efficiently into the system.
- The Collected nodules should be arranged according to its grain size and the content of the slurry in a suitable condition before transfer to the nodule lifting sub-system.
The collector system is developed separately as six pieces of equipment. They are the nodule collecting equipment, separation and supply equipment, ski/driving equipment, frame body, electric and hydro power equipment and measurement and control equipment. These are researched and developed step by step steadily through the processes of conceptual design, experiment for the elementary factors, simulation and to the verification of functions of each equipment. After that, development stage proceeds into the initial design and detailed design and finally real equipment are manufactured.
Based on these research and development processes the collector sub-system consists of fluid dredging method for the collecting equipment and open system of separator with glizzly, the skid system consists of fixed skies under the pipe frame body, the power supply equipment of 6,000 volts and a TV monitoring system.
The collector was examined successfully in the marine experiments for its driving function and nodule collecting function test. The result was excellent to confirm their efficient functions in every parameter of the collector. Much data was gathered in the marine experiment, which is useful for the design of a commercial collector system in the future.
Key words : marine resources, manganese nodule, manganese nodule mining system marine experiment, manganese nodule collector
(Language:Japanese)
Original Paper
Research and Development of Total System for a Manganese-Nodule Mining System
Kunihiro IKEGAMI, Yojiro WADA, Hironori YASUKAWA and Tohru MINAMI (Mitsubishi Heavy Industries, Ltd.)
Abstract
The abstracts of the planning for manganese-nodule collecting test in the Pacific Ocean, and the simulation and analysis for maneuvering of a towed ship and behavior of a collector are reported. The simulation method for maneuvering of a towed mining ship under external environmental loads such as wind, wave and current was developed. Maneuvering motions under various environmental conditions were calculated so that a manual can be conpiled. Availability of the simulation method was confirmed by comparing the actual test results with simulation ones. The simulation method for behavior of a collector under various conditions: collector towed at sea, collector towed at seabed and collector landing on seabed, this simulation method was adopted to put together the handling manual. Availability and limitations of the simulation method were clarified by comparison with actual results.
Key words : Manganese-nodule mining, Simulation, Motion of a towed ship, Behavior of a collector
(Language:Japanese)
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