Tetsuo Yamazaki

Tetsuo Yamazaki
Osaka Prefecture University | OPU · Department of Marine Systems Engineering

About

74
Publications
4,386
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
417
Citations
Citations since 2016
6 Research Items
150 Citations
2016201720182019202020212022010203040
2016201720182019202020212022010203040
2016201720182019202020212022010203040
2016201720182019202020212022010203040
Introduction
Skills and Expertise

Publications

Publications (74)
Article
Full-text available
An examination of the technical and economic feasibility of the combined mining of the rare-earth element-rich mud (REE-rich mud) and ferromanganese nodules (FN) around Minamitorishima (Marcus) Island in Northwest Pacific is introduced. A previous study showed that the mining of REE-rich mud around Minamitorishima Island was not economically feasib...
Conference Paper
These days, many seafloor massive sulfide (SMS) deposits have been discovered in Japan’s exclusive economic zones. They have many kinds of useful metals, and are expected to be future metal resources. However, SMS mining faces an economic problem for the reason that disposal of unnecessary parts of SMS ores is very expensive in Japan. Adding a func...
Chapter
Deep-sea manganese nodules have been of interest as future metal sources for copper (Cu), nickel (Ni), cobalt (Co), and manganese (Mn). R&D efforts of the mining technologies from the 1970s until the 2000s by international consortia and national programs are summarized. The historical trend of the mining technologies is evaluated. Seafloor massive...
Chapter
The importance of manganese nodules, seafloor massive sulfides, and cobalt-rich manganese crusts as future metal sources has been well recognized. However, less geotechnical information of the resources is available to aid the design of mining system. The results of fundamental studies for geotechnical characteristics of the resources and sediments...
Conference Paper
Many seafloor massive sulfide (SMS) deposits have been discovered in Japan’s exclusive economic zones (EEZ). They have some useful metals and are expected to become future metal resources. In Japan, because of an expensive waste disposal cost, it seems to be difficult to realize the SMS mining. Adding a function of primary waste separation from met...
Conference Paper
Because of the higher Au, Ag, and Cu contents, seafloor massive sulfides (SMS) have received much attention as future commercial mining targets by private companies and nations. One of them, Solwara 1 Project in Papua New Guinea (PNG), is scheduled to start the commercial mining operation from 2018. Because the mining site is inter-island area and...
Conference Paper
A preliminary tank experiment for clarifying the effect of micro-bubbles on settling behavior of fine particles was conducted. The behavior of the particles was continuously photographed by a still camera and the images were analyzed by the gray scale intensity. From the results the authors found a suspension effect of micro-bubbles for the settlin...
Article
Full-text available
Deep-sea mineral resources, such as manganese nodules, seafloor massive sulfides, cobalt-rich manganese crusts, and rare-earth element-rich deep-sea mud have been interested in as potential resources for metals near future because of their higher metal contents and no overburden removals. The R&D histories and current activities are introduced. In...
Article
Deep-sea rare-earth element-rich mud (REE mud) distributes in pelagic clayey sediment column on ocean seafloor at 4,000- 6,000 m deep. The thickness ranges 5-80 m and the burial depth 0-100 m. The REE contents range 600-2,250 ppm in the Pacific and one of the richest, maximum 6,500ppm, has been found near Minami-Tori-shima (Marcus Is.) in Japan's e...
Conference Paper
In Papua New Guinea (PNG), a seafloor massive sulfide (SMS) mining venture has been proposed to start in 2013 and the expected high profitability was presented. However, the geophysical and social conditions are quite different from Japan’s ones. The technologies and model used for the PNG mining are difficult to apply under Japan’s conditions. The...
Conference Paper
Various unconventional natural resources (e.g. seafloor massive sulfide, methane hydrate and manganese nodules) existing on and under the seafloor will possibly be mined in the near future. When mining these deep sea resources, it is necessary to monitor the environmental impacts of seafloor mining. Environmental impacts have been usually monitored...
Article
Seafloor massive sulfides (SMS) which contain Au, Ag, Cu, Zn, and Pb have been interested in as a target of commercial mining these 15 years. Japan has large potential of SMS and a national R&D project for the mining has been active these 5 years. However, the economy of SMS mining is very bad, because the waste tailing disposal cost is very expens...
Conference Paper
Because of the higher Au, Ag, and Cu contents, seafloor massive sulfides (SMS) have received much attention as immediate commercial mining targets by private companies and nations. One of them is scheduled to start the commercial mining program in the end of 2013 and the expected profitability is presented. However, the geophysical and social condi...
Conference Paper
Full-text available
Manganese nodules on deep ocean floors have been interested in as future metal resources these forty years. The Total Materials Requirement (TMR) of the conventional proposed mining method, however, is very high because of the much lifted water with the nodules from the seafloor to the sea surface and the longer transportation from the mining site...
Chapter
Deep-sea mining has been a subject of interest for several groups and countries for over four decades, due to its potential for the economical recovery of large reserves of minerals that would provide an alternative resource of strategic metals for industrial development. A deep-sea mining operation will offer a variety of challenges, owing to deep...
Conference Paper
Full-text available
Seafloor Massive Sulfides (SMS) including Au, Ag, Cu, Zn, and Pb exist in exclusive economic zones (EEZ) of the Pacific island countries. Some of SMS are interested in as immediate targets for commercial mining ventures. Little information, however, is available for the mining impacts on marine ecosystem, because no actual deep-sea mining operation...
Conference Paper
It is necessary to carry out a proper environmental impact assessment for not only the sea-floor massive sulfide area where a special hydrothermal-vent chemosynthetic ecosystem is observed, but also its surrounding area. This paper shows provisional results of the environmental baseline survey conducted at the Izena Cauldron in 2009. Environmental...
Article
For the ecological risk assessment of mining of Seafloor Massive Sulfides (SMS), three kinds of ecological risk that could be caused by the mining were identified using a mining plan. To assess the effect of the direct disturbance of seafloor on benthic organisms, the ecosystem model that deals with recovery process of benthos from elimination with...
Article
Seafloor Massive Sulfides (SMS), which are formed by deposition of precipitates from hydrothermal fluids venting from deep seafloor, are one of unconventional mineral resources. In the Japanese waters, some desirable SMS sites have been found at the depths of 700-1600m. In the master plan for development of seafloor resources including SMS in the E...
Article
Seafloor Massive Sulfides (SMS) including Au, Ag, Cu, Zn, Pb and some rare earth elements exist in exclusive economic zones (EEZ) of Pacific island countries and the ones in Japan's EEZ are the largest and very much attractive. However, there are many problems to be solved for the development. The most important point is the location of ore dressin...
Article
High primary biomass production and dense population are found around hydrothermal vent system. High fluxes, especially hydrogen sulfide, from hot water support this chemosynthetic community. Nowadays, some mining programs of seafloor massive sulfide ore body nearby the vent system are under progress. In order to estimate the environmental impacts...
Article
Sediment properties, such as water content and density, have been used to estimate the dry and wet weights, as well as the volume of sediment recovered and discharged, during benthic impact experiments conducted in the Pacific and Indian Oceans. The estimates show that the weights of dry (355-1332 t) and wet sediment (1651-4888 t) recovered during...
Conference Paper
Full-text available
Seafloor massive sulfides have been a subject of interest for profitable commercial mining these ten years. However, less information is available for both the baseline ecosystems in the distribution areas and the environmental impacts on them caused by the mining. Owing to growing concern for the global and local environments, the quantitative und...
Conference Paper
Full-text available
The importance of cobalt-rich manganese crusts on the Pacific seamounts for possible future rare metal sources has currently been recognized. The thin layer-type deposit characteristics affect not only the excavation efficiency but also the economy of mining venture. Considering the thin layer-type distribution and the utilization of some rare meta...
Article
Recently, measurement of certain environmental factors such as dissolved oxygen and chlorophyll using electric sensors has been realized. Such measurement is continuous and automatic, and is very important for monitoring the environment in sea areas. However, it is difficult to continuously measure nutrient, hydrosulfide and so on, because data mus...
Article
There are chemosynthetic ecosystems nearby deep-sea mineral and energy resources such as seafloor massive sulfides and methane hydrate. A prediction model that predicts the response of the ecosystems due to changes in environmental condition should be developed to assess the impact of deep-sea resource development on environment including chemosynt...
Conference Paper
Deep-sea mining has been a subject of interest for several groups and countries for over four decades, due to its potential for the economic recovery of large reserves of minerals that would provide an alternative resource of strategic metals for industrial development. A deep-sea mining operation will offer a variety of challenges, owing to deep-s...
Conference Paper
In order to take measures against environmental impacts during the process of mining seafloor massive sulfides (SMS), it is important to measure some of the components of hydrothermal origin with high resolution in time and space on-site as well as to understand the ecosystem in the hydrothermal environments. The adoption of spectrophotometry for m...
Article
The importance of cobalt-rich manganese crusts on the Pacific seamounts for future rare metal and rare earth element resources has currently been recognized. The thin layer-type deposit characteristics affect recovery efficiency of the deposit, degradation of the mined ore, and the economy of the mining venture, when the microtopographic undulation...
Article
Manganese nodules on deep ocean floor have received continuous attention as future resources for Co, Ni, Cu and Mn last five decades. The mining is a large-scale and long term venture. However, very few ecological assessments have been reported for it, due to the lack of a suitable assessment method. In this paper, the authors have applied an evalu...
Article
Transition ecosystem area from chemosynthetic community at active hydrothermal venting site to normal seafloor one is the expected place of mining seafloor massive sulfides. No data is available for the distribution characteristics of ecosystems in the transition area. Using visual seafloor observation data obtained by a towed camera system, a prel...
Article
The distribution characteristics of chemosynthetic communities around seafloor massive sulfide deposits provide important quantitative background information for the understanding of these sensitive ecosystems. Using visual seafloor observation data obtained by a towed camera system, a preliminary quantification approach of the distribution of chem...
Conference Paper
The Kuroko-type seafloor hydrothermal deposits, sometimes known as seafloor massive sulfides (SMS), are currently the hottest business targets in ocean mining field, because metal prices included in the deposits tend to be several times or more expensive than the ones a few years ago. Therefore, two private venture companies have been very active f...
Conference Paper
Full-text available
Natural cold seepages are characterized as rapid upward transports of methane from deeper parts of geological structures to the seafloor. The original methane supply source is expected to locate below BSR (Bottom Simulating Reflector). The methane moved up to seafloor is mainly consumed by microorganisms living in anoxic marine sediments. When the...
Article
Full-text available
In Japan, the potential use of natural methane hydrate as an energy resource has been emphasized, and a national R&D project named MH21 to locate deposits and to develop exploitation technologies has been conducted. Since there are less domestic oil and natural gas resources in Japan, the highly attractive possibility for energy resource and the ma...
Article
Natural cold seepages are characterized as rapid upward transports of methane from deeper part of geological structures to the seafloors. Prior to reach the seafloors, when methane meets downwards diffusing seawater sulfate, it is oxidized anaerobically by a consortium of microorganisms that use sulfate as an oxidant, producing sulfide. The anaerob...
Article
Full-text available
A mass balance ecosystem, model of a chemosynthetic community around natural cold seepages in sediment layer and on the seafloor has been created numerically. Though the model is in preliminary form, the mechanism, and functions necessary to support the community are fundamentally solved. A quantitative evaluation of the ecosystem may be possible g...
Conference Paper
Metal market prices drastically changed from 2002. Not only the price of iron but also the ones of copper, nickel, cobalt, and manganese quickly rose in the market. Economic growths of Asian countries, especially China, have induced the situation. Results of economic validation analyses of Japan's nodule, crust, and Kuroko-type SMS mining using upd...
Article
Full-text available
A mass-balance ecosystem model around natural cold seepages on the seafloor has been studied. One component of the model is a water column methane consumption process unit. The detailed structure of the unit, which is composed of a bubble blow-up process and a plume dissolution and dispersion process with methane oxidation, is introduced. The resul...
Article
Natural methane hydrate has been scientifically studied as a carbon reservoir globally. However, in Japan, the potential for energy resource has been industrially highlighted. There is less domestic oil and natural gas resources in Japan, but many potential deposition areas for methane hydrate in ocean around Japan are the reasons. Less CO2 dischar...
Article
Full-text available
Potential of natural methane hydrate for an energy resource has been highlighted in Japan and a national R&D project to find out the deposit locations and to develop the exploitation technologies has been conducted. However, because methane hydrate distributes in shallower sediment layer in ocean floor, accidental leakage of methane may occur durin...
Article
Geotechnical properties of deep-sea sediments which have important roles for design of manganese nodule miner and mining system are presented. They are water content, vane shear strength, sensitivity, cone penetration resistance, cohesion, friction angle, and dynamic moduli of elasticity and viscosity. The interactions with the miner are examined....
Article
Seafloor massive sulfides found in the western Pacific have been considered to be potential Au, Ag, Cu, Zn, and Pb sources. The geological distribution characteristics of seafloor massive sulfides have been widely studied. However, physical and geotechnical properties such as density, porosity, strength, and hardness have not yet been clarified. We...
Article
The Kuroko-type seafloor massive sulfide deposits found in the western Pacific have been considered to have potentials for economic recovery of Au, Ag, Cu, Zn, and Pb. The technical and economic feasibility of mining is preliminary evaluated in this case study. The Sunrise Deposit of Myojin Knoll on Izu-Ogasawara Arc in the Japanese EEZ is selected...
Article
The Environmental Impact Research on Marine Ecosystem for Deep-sea Mining has been conducted from 1998 to 2002 for establishing quantitative methods to estimate environmental impacts on marine ecosystem on deep seabed likely to be caused by mining operations for mineral resources. This research program was composed of the baseline study, the artifi...
Article
Cobalt-rich manganese crusts on seamounts and manganese nodules on deep ocean floor have both been received attention as future resources for Co, Ni, Cu, and Mn. Lack of information on cobalt-rich manganese crusts has precluded comparisons between the two sources in terms of their technical and economical advantages. In the past 15 years, Japan has...
Article
Cobalt-rich manganese crusts on seamounts and manganese nodules on deep ocean floor have both received attention as future resources for Co, Ni, Cu, and Mn. Lack of information on cobalt-rich manganese crusts has precluded comparisons between the two sources in terms of their technical and economical advantages. In the past 15 years, Japan has surv...
Article
It is expected that some of the deep-sea sediments will be lifted along with water and manganese nodules by a hydraulic transportation system, and either be discharged near the seafloor or at the surface. This discharge may create a turbid sediment plume, changing the physicochemical conditions of the surrounding waters, and affecting the ecosystem...
Article
An artificial resedimentation was created in the Clarion-Clipperton Fracture Zones, where is one of dense manganese nodule areas in the Pacific, in 1994 for impact assessment on seafloor environment. In order to quantify the resedimentation, an image analysis technique of the seafloor photographs was developed. Subsequent artificial disturbances on...
Article
Several groups of mining engineers and environmental scientists have been conducting studies for the assessment of environmental impact and additional disturbance on the deep seabed. These studies influence the development of an individual mining system and its subsystems for the collection, screening and lifting of deep-sea minerals and their tran...
Article
An artificial impact experiment named DIETS, whose objective was an analysis of the direct destruction of the benthos occurring in the running tracks of a nodule collector, was conducted in a terrace on a seamount in the southeast region of Marcus Island in 1999. The depth was 2,200 m, and the nodule population was 15 kg/m2 in the terrace. In the e...
Article
Environmental impact researches for manganese nodule mining have been progressive in many countries. The current status in the world is introduced. Fundamental understanding about deep-sea environment obtained by the Japan's research and results of the impact experiment to it are introduced. Requirements of in-situ long term and continuous monitori...
Article
A large-scale nodule collection test at ocean was conducted in 1997 at the end of a Japanese national R&D project of manganese nodule mining system. The collector passes were observed by a ROV, a side scan sonar, and a towed seafloor observation camera system for the post-test evaluation. Preliminary analyses of the results are introduced in the pa...
Article
Full-text available
Distribution characteristics of cobalt-rich manganese deposits were evaluated from stereo photographs and video data on a seamount in the central Pacific Ocean by image analysis, photogrammetric technique, and visual observations. The results show that many locations have high crust coverages with highly undulating microtopography. High nodule cove...
Article
Cobalt-Rich Manganese Deposits (CRMD) is one of underwater mineral resources which is cobalt supply. In order to mine this CRMD efficiently, it is important to understand such engineer properties of CRMD and their substrates, as P-wave velocity, specific gravity, strengths and so on. But these engineering properties have not been well known yet. Be...
Article
Full-text available
Cobalt‐rich manganese deposits on Pacific seamounts have become a focal point as one of the marine mineral resources with the most potential for the twenty‐first century. Extent and distribution of the deposits have not yet been well determined. Conventional survey techniques have estimated the distribution of the deposits by the surface coverage o...
Article
Full-text available
Geotechnical properties and distribution characteristics of the Pacific seamount sediments, which coexist with cobalt‐rich manganese deposits (crusts and nodules), are essential data for the design of a seafloor mining system for the deposits. Samples were cored by a large‐diameter gravity corer during the research vessel Hakurei‐maru No. 2 survey...
Article
Full-text available
The importance of deep-ocean deposits for future cobalt resources and geological distribution characteristics have been well recognized. However, no sufficient geotechnical information of the cobalt-rich manganese deposit region is available to aid the design of seafloor mining systems. Based on the results of a recent large-diameter gravity coring...
Article
Full-text available
Evaluation of stereo photographs and video data shows a variety of surface features associated with the crusts and nodules across a mid‐Pacific seamount. The differences in the coverage, distribution, and relief are used to classify the surface features. The crust outcrops have large coverage (up to 100%), and their surface features vary from stepl...
Article
Full-text available
Cobalt-rich crusts on seamounts have been considered a potential mineral resource for the 21st century, and mining programs have been assessed in Japan during recent years. The crust distribution characteristics are not yet clearly known, although the United States, Germany, France and Japan have been conducting its exploration. So far the potentia...
Article
In the case of lifting of manganese nodules by air lift pump, gas-liquid-solid three phase flow is formed in lifting pipe. Accordingly, its lifting characteristics are influenced by the length and diameter of the lifting pipe.We considered static pressure profile, flow pattern and average hold-up from the experimental results of a 200m vertical tes...
Article
The effort of the research and development of manganese nodule mining system from deep ocean floor has been concentrated in several countries this decade. Among many sub-systems of the mining system it is said that the development of collector system which harvests manganese nodule on the sea floor involves most difficult problems. The engineering...
Article
Full-text available
There are practical and financial difficulties to measure gas permeability of coal seams. So we tried to evaluate gas permeability of a coal seam using permeabilities of small lump coal samples. From the results of measurement it was shown that; 1) Gas permeabilities of coal samples are distributed between very wide range, i.e. 10⁻⁷-10⁰ darcy. 2) T...
Article
Full-text available
The movement of methane gas in the coal seam has been observed by use of tracer gases in several coal mines in HOKKAIDO. Radioactive methane and freon gas were used as tracer gases. Results gained are as follows. (1) Almost all quantity of the methane gas in the coal seam moves through cracks, And seams which have no crack are scarcely permeable. (...
Article
Method of exploitation, selection of mine site and desing of mining system of cobalt-rich manganese deposits on seamounts would be greatly influenced by the distribution characteristics as well as the associated seabed features, wuch as the seabed topography, surface morphology and sediment characteristics. An example detailed analysis of the distr...
Article
Evaluation of seafloor stereo photographs, video data, and large diameter gravity core samples shows a variety of surface features associated with the crusts, nodules, and sediments covering mid Pacific seamounts. A set of deep sea stereo camera and a color video camera mounted on a deep tow vehicle with CTD system was used on the research cruise,...

Network

Cited By