Carbon-dioxide Capture and Storage (CCS) has been topical research since CO2 is required to reduce from atmosphere as one of greenhouse gas. CO2 geological sequestration can be learnt from the CO2 enhanced oil recovery (CO2-EOR) technologies applied to the oil industry since there are many projects and developments around the world. In this paper, the pilot tests and their related research conducted by Japan National Oil Corporation (JNOC) and Japan Oil, Gas and Metals National Corporation (JOGMEC) are reviewed in order to contribute to the CCS technologies. The pilot tests conducted in Kubiki, Ikiztepe and Sarukawa oil fields with the reservoir simulation studies, laboratory experiments and facility designs are mainly discussed. In addition, some feasibility studies for Kuwaiti, Abu Dhabi and Mexican oil fields are also reviewed. Most of the technologies reviewed in this paper are also useful to the CCS and give the shortcut to successful CCS projects.Carbon-dioxide Capture and Storage (CCS) has been topical research since CO2 is required to reduce from atmosphere as one of greenhouse gas. CO2 geological sequestration can be learnt from the CO2 enhanced oil recovery (CO2-EOR) technologies applied to the oil industry since there are many projects and developments around the world. In this paper, the pilot tests and their related research conducted by Japan National Oil Corporation (JNOC) and Japan Oil, Gas and Metals National Corporation (JOGMEC) are reviewed in order to contribute to the CCS technologies. The pilot tests conducted in Kubiki, Ikiztepe and Sarukawa oil fields with the reservoir simulation studies, laboratory experiments and facility designs are mainly discussed. In addition, some feasibility studies for Kuwaiti, Abu Dhabi and Mexican oil fields are also reviewed. Most of the technologies reviewed in this paper are also useful to the CCS and give the shortcut to successful CCS projects.
Compositional and structural properties of clay minerals from hydrothermal systems show highly diverse and systematic variations related to their localities. The chemical compositions of chlorite, one of the most common clay minerals, are thought to have a close relationship with its formational environments such as geological conditions, temperature, chemistry of hydrothermal solution, etc. In this study two chlorite geothermometers were considered by using the chemical composition of chlorites from some hydrothermal ore deposits in Japan. The two chlorite geothermometers are the Cathelineau's thermometer giving an empirical temperature scale of chlorite formation in an active geothermal field, and the Walshe's thermometer giving a thermodynamic temperature scale based on exchange reactions of chlorite solid solutions. On the basis of a comparison of fluid inclusion geothermometry, it is concluded that the two geothermometers can be applied to different compositional types of hydrothermal chlorite. The Cathelineau's thermometer fits well for Mg-chlorite, and the Walshe's thermometer fits for Fe-chlorite, indicating that both two chlorite geothermometers can be used as exploration indicators for geothermal reservoirs and hydrothermal ore deposits. In addition, it must be emphasized that the impurities in the chlorite should be examined in applying the chlorite geothermometers to chlorites.
Accurate modeling of geology, rock fracture, and geologic property distributions is an important problem for natural resource explorations, rock engineering, and underground storages of CO2 and high-level radioactive wastes. This paper presents 3D spatial modeling techniques that are suitable for clarifying these distributions for a wide study area. The techniques are composed of two methods, OPTSIM for discontinuous geologic layers and physical properties and GEOFRAC for fractures including joints and faults. A mechanical minimization criterion and a stochastic simulation were combined for OPTSIM. GEOFRAC is a geostatistics-based method which incorporates the orientations (strikes and dips) of sampled fracture data into the simulation. Fracture locations are generated randomly following the fracture densities assigned by a sequential Gaussian simulation. Fracture orientations are transformed into an indicator set consisting of eight binary variables and the variables are compressed using the principal component analysis. Ordinary kriging is then employed to estimate the distributions of these principal values and the results are back-transformed into the original coordinate system. Fracture orientations are generated randomly using their histograms within the defined directional sector. Finally, fracture facets are determined from the simulated locations and orientations, and the fractures within the angle and distance tolerances are connected to form a fracture plane. The Tono Area, chiefly underlain by Cretaceous granite in central Japan, was selected as a study area, because this area includes the 19 deep boreholes raging from 500 to 1000 m depth. The main target area size is 12 km (E-W) , 8 km (N-S) , and 1.5 km depth range. GEOFRAC was shown to be able to draw a plausible fracture system, because the simulated orientations reproduced those measured: in addition, the locations and directions of the continuous fractures corresponded to the zones of abrupt changes of resistivity and P-wave velocity and the known main faults.
The spatial distribution of hydrogeologically-relevant geological structures such as fracture and fault is usually very heterogeneous, varying, in general, according to geological history, scale of observation and rock type. With the objective of improving analytical methods to better understand structural heterogeneities, this paper describes the results of investigations of the spatial relationship between regional geological structures (Tsukiyoshi fault and Tsukiyoshi paleo-channel) and fracture density with special emphasis on low-angle fractures in the Toki granite, central Japan. As a result of the analysis, positive correlations between average of fracture spacing data and the horizontal distances from two regional geological structures have been observed. Because the positive correlations can be approximated with a polynomial function of the response surface, we have obtained an improved understanding of the spatial distribution of low-angle fractures with respect to the location of regional geological structures. We have interpreted that the observed spatial distribution of low-angle fracture density conforms to the tectonic setting, on the assumption that the Tsukiyoshi fault and Tsukiyoshi paleo-channel are probably associated with the pull-apart basin by strike-slip faulting from the past investigations and geophysical surveys for this research area. In addition, the proposed spatial modeling techniques and geological interpretations are able to evaluate certainty of interpreted faults and fractures distributions, quantify general trend in structural heterogeneities and detect unknown faults.
Lithofacies discrimination has been conducted using the full- and dual-polarimetric ALOS/PALSAR data in the semi-vegetated Kalgoorlie area, WA, Australia and vegetated Lao Cai area, Northern Vietnam. In the Kalgoorlie area, characteristic features of topography, vegetation and surface roughness affected by the difference of geological units were noticed from simple scatter component image of PALSAR and multi frequency image using PALSAR and ENVISAT/ASAR data. In the Lao Cai area, the relation between polarimetric characters data and lithofacies are not recognized due to the thick vegetation and steep slope, however, the geological boundaries between metamorphic, igneous and sedimentary rocks are detected by using coherence information which is computed within InSAR processing.
It is well-known that granite has anisotropy due to the preferred orientation of micro-cracks. Therefore, it is important to investigate the orientation of micro-cracks in granite to discuss the anisotropy. It has been postulated that the orientation of micro-cracks in rock can be determined by DSCA (Differential Strain Curve Analysis). In the case of DSCA, however, it is necessary to use a lot of specimens to determine the orientation of micro-cracks precisely. Additionally, it is impossible to evaluate the orientation of micro-cracks if the rock contains few oriented micro-cracks. The seismic wave velocity shows the extreme values in the direction of principal axes of elasticity. Therefore, it is possible to obtain the information of the orientation of micro-cracks in rock by the measurement of the wave velocities. In this study, longitudinal wave velocities in various directions were measured to determine the orientation of micro-cracks in granite by using polyhedral specimens. From the measurement of the longitudinal wave velocities, the three-dimensional distribution of the velocities in granite could be obtained. By using the associated Legendre function, it was shown that the three-dimensional distribution of the longitudinal wave velocity could be approximated within 2nd order terms of the associated Legendre function. This result means that the wave distribution function can be expressed with the quadric surface and the coefficients can be expressed as the symmetric tensor of the 2nd rank. This shows the existence of the principal axes and the principal values which can be expressed with the eigen values and the eigen vector same as the cases of the stress and the strain. It is concluded that the directions of the principal axes and the values of the longitudinal wave velocities in granite can be determined by the calculation as evaluating the principal stress or the principal strain from the stress tensor or the strain tensor.
Understanding mechanical behavior of frozen rocks is useful for evaluating the stability of rock slopes in cold regions. In this study, uniaxial compression tests and Brazilian tests were carried out on frozen rock specimens of welded tuff and andesite under -20°C temperature. The fracture process was examined by observing deformation behaviors and AE activities. Effects of water saturation degree on strength and deformability were also investigated. The main results are as follows. 1) The fracture process of the frozen rock was similar to that of non-frozen rock and was divided into the following regions. (I) Closure of cracks and pores. (II) Elastic deformation. (III) Fracture initiation and stable fracture propagation. (IV) Unstable fracture propagation. Also, stress levels at the beginning of the region (III) increased with the degree of water saturation. 2) Both strength and strain at peak stress increased as the degree of water saturation increased. The relations between them were able to be approximated by a straight line. Brittleness of rocks decreased with the degree of water saturation since indirect tensile strength was more sensitive to the degree of water saturation than uniaxial compressive strength. 3) The mechanical effect of frozen pore water was considered with an inclusion model. The model predicted the observed phenomenon. Namely, increment in fracture initiation stress, due to frozen pore water in uniaxial tension, was always higher than that in uniaxial compression. The increase in strength was thought to result from relaxation of stress concentration around pores.
For a couple of decades, creep of rock has been one of the research topics, but little knowledge has been obtained concerning long-term creep behavior under low stress level. To estimate the long-term stability of underground structures, it is important to know how creep strain rate will change for a long time, and to know whether or not creep strain will asymptotically approach a constant value under low stress level. In this study, creep testing machine and high-accuracy measuring system were developed for long-term accurate testing. In 1994 uniaxial compressive creep test with Tage tuff was started under the stress level of 30% (ratio of creep stress to strength) in wet condition, but in 1996 this test was halted due to measuring equipment fault. Then the countermeasure was examined to continue the test when equipment fault may happen. In 1997 creep test with another specimen of Tage tuff was started, and has continued for ten years without any problems. Experimental results showed that creep strain of Tage tuff has been continuously increasing for ten years under such a low stress level. Creep strain rate, however, has been rapidly decreasing in proportion to about -0.9th power of elapsed time. Experimental results of long-term tests in this study and short-term tests in earlier studies were compared with the aid of non-linear visco-elastic theory, and it was found that both of them had many similar features.
A shear-flow test under constant normal stress to clarify anisotropic and heterogeneous water flow of a rock fracture was carried out using a true triaxial compression test apparatus. The main results in this study can be summarized as follows: 1. The hydraulic conductivity in rock fracture shows remarkable anisotropy and heterogeneity with increase of shear displacement due to the formation of both channels and ridges. This anisotropy becomes more remarkable with shear displacement. However, hydraulic conductivity of whole flow area is not influenced by this anisotropy. 2. Spatial distribution of the aperture during shearing plays an important role in anisotropy of hydraulic conductivity of the fracture. 3. In this study, the hydraulic aperture eh is almost constant until the shear displacement is 13.4 mm, and decreases dramatically when the shear displacement exceeds 13.4 mm. It was considered that water flow was inhibited since contact stations of the aperture are enlarged and localized as shear displacement increases. Moreover, it was clarified that an accumulation of gouge which was produced by shearing becomes an important factor of dramatic decrease of hydraulic conductivity.
As a fundamental study for support design of underground space using cable bolt, a series of laboratory pull-out tests were conducted. In the test, two types of cable bolts, namely plane strand cable bolt and bulb strand cable bolt, were used. The embedment lengths of cable bolts were 350mm and 4000mm. Then the mechanical behavior of cable bolts in the pull-out tests was analyzed, focusing axial force and axial displacement of cable bolt, confining pressure from surrounding rock, inner pressure acting on the boundary between cable bolt and grout. The mechanical behavior is dependent on not only type of cable bolt but also Young's modulus of surrounding rock. Both cable bolts are ineffective to increase pull-out load in the case of soft rock and effective in the case of hard rock. Because that the confining pressure from surrounding rock to cable bolt in the case hard rock is stronger than that in the case of soft rock.
The Hishikari Mine consists of epithermal vein type Au-Ag deposits. The veins are extracted mainly by drifting and bench stoping with backfill. Blasted waste rocks are generally used as backfilling materials and crushed waste rocks with cement are used for larger stopes. Although backfilling controls the displacement of excavation surface and increases the stope stability, practical evaluation for stope dimension in conjunction with backfilling effects is not established. In this study, supporting effects of stope ends were evaluated and available support lines were drawn by using a three-dimensional elastic finite element analysis. Based on available support lines, the properties of backfilling materials were evaluated. The behavior of rock mass in bench stoping was compared with a two-dimensional elasto-plastic finite element analysis. The results indicated more remarkable influence on the stope stability with the backfill stiffness. The Young's modulus of the backfilling materials containing cement at the Hishikari Mine changed from 10 MPa to 1 GPa by numerical analyses and field measurements.
Deformation and failure behaviours of rock masses are governed by both characteristics of geometrical distribution of discontinuities and those of mechanical behavior in a single discontinuity in slopes. It is thought that stability of those rock structures extremely depend on not only the existed discontinuities but also the new cracks which are newly generated by weathering and degradation of rock masses. Therefore, how to evaluate the behaviour of cracks in the rock masses becomes a key problem to assess the long-term deformation and stability of the jointed rock slopes. In this paper, the behaviours of rock slope around a reservoir are evaluated by using the extended distinct element method (EDEM) . The appropriateness of the proposed approach is verified by means of the comparison with the field data. It has been clarified that the proposed numerical approach could be used as an effective method to build a long-term stability management of a rock slope.
Results from distinct element method (DEM) simulations are presented for the uniaxial compression test, cyclic loading test considering the Kaiser effect, and hydraulic fracturing, and the applicability of DEM to model rock fracture is discussed. Each simulation was in good agreement with the actual experimental results. It is shown that DEM is an effective technique to mimic fracture within a heterogeneous material. However, it was found that there are unresolved issues to be considered in the application of DEM to rock fracturing. (1) For proper simulation using DEM, appropriate micro-parameters are needed. In spite of efforts by many researchers, there are no effective procedures to find an optimum set of parameters. (2) Conventional DEM simulations assume generation of new cracks to be acoustic emission (AE) events, whereas slip occurring at the preexisting crack surfaces also generates AE. To better understand the mechanism of rock fracture, it is necessary to discuss the generation mechanisms of such AE events. (3) For a field scale simulation, the important problem of grain size, as well as input parameters, has not yet been resolved.
A force-penetration relationship is considered to be closely related to the deformation and fracture mechanism at the bit-rock interface. In this study, a series of percussive long-hole drilling tests using Inada granite were carried out to examine the effects of hole length on drilling performace. Stress wave was measured by a pair of strain gauges, and then force-penetration curve of a button bit was calculated by the measured stress wave. The main results are summarized as follows: 1) It can be said that characteristic impedance of hard metal chips has negligible effect on the calculated force-penetration curve, but characteristic impedance of the bit and travelling time from strain gauges to the bit have considerable effect. 2) With increase of hole length, the energy transmitted to the rock decreases, damage around the bottom of the hole decreases, and then the variation in slope of each force-penetration curve decreases. 3) Average advance per blow of rock drill can be expressed by following equations: (Average advance per blow of rock drill) = 0.26× (Maximum penetration) = 0.51× (Final penetration) .
In recent years, many trenchless rehabilitations of pipeline that are considered of residents' living environment and mitigated the influence on traffic have been developed. Although the grouting material is required to make the established pipe and the lining material unify, it has high mobility etc. The grouting material using the material that was mixed the surface-active agent with the flyash was developed. Usage of flyash instead of cement leads to improving mobility, reducing construction cost and so on. In this paper, in order to examine the effect on ambient surroundings of the mixture material developed as grouting material, a fundamental investigation is performed and various these results are discussed.
When underground piping for a water or gas supply is buried, the construction site should be checked in advance, referring to the plan or sign. However, some obstacles, such as unknown pipes or stones, can be encountered. To avoid these cases, an examination of the underground condition is required. The purpose of this study is to detect underground objects that exist in the ultra-shallow layer, where 2-3 m below the surface, and to obtain underground image which is easy to see intuitively. For detection, seismic method is applied. However, this method has two downsides. One is a generally used seismic source not having reproducibility. The other is mixing Rayleigh wave which is one of the surface waves and reflected waves. To compensate these downsides, giant-magnetostriction vibrator was used as a seismic source, and magnified cross-correlation analysis was proposed. Underground image was obtained using combinations of them. In this paper, as the method of underground imaging, new algorithm of elliptic orbit brightness value it was developed by the authors was used.
We have already developed a new recycling system for high-water content mud by using paper debris and powder polymer in order to increase the recycling rate of the construction sludge and water purification sludge.Modified soils produced by this system have several features such as high failure strength, high failure strain and high durability for drying and wetting. In spite that modified soils have several features, the utilization of modified soils as landfill materials is not largely increasing because a large amount of free excavated soils which are competing goods of modified soils remains. Therefore, in this study, the utilization of modified soils as planting soils is focused. In the recycling system developed previously, the addition rate of paper debris is determined based on the water content of the mud. However, it is difficult to produce the planting soils of constant quality because soil/paper mass ratio is not always constant if the water content of the mud is different. Therefore, the purpose of this paper is to investigate the optimal soil/paper mass ratio from the view point of soil physical properties and to produce the planting soils of constant quality regardless of the water content of the mud. It was confirmed through the experiments that the most appropriate soil/paper mass ratio was in the range of 5-6. In case of wet type planting soils, it was impossible to satisfy all target values, but it can be considered that the quality of wet type planting soils will be improved and they will satisfy all target values if the other lightweight construction wastes such as wooden chips are mixed with wet type planting soils.
Recently, a mobile soil-recycling machine has been receiving considerable attention in order to recycle the excavated soils produced from the construction sites. This machine is also used to remediate the contaminated soils. Some researches have been already carried out in order to investigate the effects of mechanical factors on the mixing performance of excavated soils and additives. However, there are few researches related to the effects of soil properties on the agitation torque and discharge rate. Because the mixing performance is affected by not only mechanical factors but also soil properties, the investigation of the effects of soil properties on the agitation torque and discharge rate is very important to perform the safe and effective recycling work of excavated soils. Therefore, in this study, the effects of soil properties on the agitation torque and discharge rate were experimentally investigated. The results obtained in this study were summarized as follows: (1) The discharge rate and agitation torque were strongly affected by the soil properties and water content, and they increased linearly with increasing the packing rate in the mixing chamber. (2) It was confirmed that the working performance which is defined by the discharge rate per unit agitation torque showed minimum at a certain water content. Once the water content exceeds this value, the working performance increased rapidly. Especially, this tendency was significant for clay soil. Therefore, if the water content is close to the one which leads the minimum working performance, the adjustment of water content by adding water is necessary. (3) It was confirmed that the agitation torque is largely affected by the cohesive force and internal friction angle for clay soils. In the case of sandy soil, the internal friction angle affects the agitation torque. However, the factors which affect the agitation torque are considered besides the internal friction angle. Therefore, further investigations are still needed.
Japan has a manganese nodule mining claim in the Clarion Clipperton Fracture Zones, the Kuroko-type massive seafloor sulfide deposits (SMS) and cobalt-rich manganese crusts (CMC) in Japan's exclusive economic zone (EEZ) and the continental shelves. Japan needs to use these deep-sea mineral resources as future strategic metal and rare earth element supply sources. Furthermore, the development technologies have wide variations in applying for the other food and energy supply targets in EEZ and continental shelves and the same-type resources of Pacific island nations'. Some current topics in deep-sea mineral resources development and the development technologies are introduced. Possibility and necessity of deep-sea mineral resources development for Japan are discussed.
Although development of any kind in deep-sea areas must abide by environmental protection rules, human activities in these areas continue to increase. Development of deep-sea mineral resources will be one of the most intense human activities in the area. However, the characteristics unique to deep-sea environments are not well understood, making it difficult to design environmental assessment programs. From the 1970s, a series of environmental assessment studies for development of manganese nodules has been conducted. Those effects brought a lot of basic knowledge of deep-sea environment, and made it possible to predict magnitude of environmental impact caused by mining activities. And these led to the issue of the environmental protection guideline by the International Seabed Authority in 2001. Currently, seafloor massive sulfide (SMS) , which is one of the deep-sea mineral resources, is attracted attentions as a new mineral resource. To develop it, similar to the case of manganese nodules, an environmental assessment program is indispensable. The knowledge provided from experience of the manganese nodules development will be useful to make the new assessment program. On the other hands, due to many people concerned with the problem of the sea, there are many contemporary problems that we cannot cope with from past experience. To understand this situation and solve those problems, ocean governance with broad scope is necessary.
Because of the depletion of terrestrial mineral resources, the recovery of base and precious metals from deep-sea mineral resources is sure to become of significant importance. Although pyro- and hydrometallurgical processes have been developed to recover valuable metals from deep-seabed ferromanganese mineral resources, another possibility is the application of biohydrometallurgical processes. The use of microorganisms to facilitate the extraction of metals from minerals is referred to as "bioleaching" which is an economical and environmentally friendly process. The bioleaching of terrestrial sulfide minerals has developed into a successful and expanding area of biotechnology: commercial heap bioleaching is typically used for low-grade sulfide ores of 0.5% or less Cu, and commercial tank bioleaching is used mostly in the pretreatment of gold ores. The bioleaching technologies can be applied to metal extraction from deep-sea hydrothermal sulfides as well as terrestrial sulfide minerals. However, little attention has been given to the bioleaching of oxide minerals such as ferromanganese crusts and nodules. A new bioleaching system has been more recently proposed for ferromanganese crusts and nodules, in which dissolved Fe (II) is microbially produced by the Fe (III) -reducing bacterium and simultaneously used to extract Co, Ni and Mn under anaerobic conditions. The proposed bioleaching is a potentially attractive method, with good metal extractions taking only 7 hours of batch operation at room temperature and neutral pH. Further research should be planned to clarify the bioleaching behavior of other elements such as rare earths, Ti and Mo from deep-sea ferromanganese crusts. It can be concluded that bioleaching is an attractive processing route to recover valuable metals from deep-seabed mineral resources.
During the past two decades, China had achieved remarkable economic growth with the annual average increase in GDP (Gross Domestic Growth) by 10%. The strong economic growth was aided by increasing domestic investment and export-oriented industrial production particularly after the participation of WTO (World Trade Organization) in 2001. In 2007, China ranked number one metal consuming country of copper,lead,zinc,nickel, aluminium and so on. Along with the expanding demand of metals, China became importing country of many mineral commodities except for rare metals such as rare earth,antimony and tungsten etc. With the rapid increase of metal consumption, LME metal prices has been rising since 2003. Particularly, copper, zinc and nickel prices 4~6 times higher during 2003-2007. Especially, 2006 prices were skyrocketing, and even now in 2008 maintains the higher level of copper,aluminum,gold and so on. Higher metal prices are supported by expanding metal demands mainly by China, and inflow of speculative market into mineral commodity. The current higher metal prices have a great influence on world mining industry, and creating several issues from the viewpoint of countries, corporation, and stake holders. This paper includes (1) current soaring prices of metals , (2) fact of expanding mineral consumption in China, (3) impact of higher metal prices on world major companies, (4) influences on Japanese smelting companies.
Following the Chinese economic reform program at the end of the 1970s, the Chinese economy started growing steady, and around 2001, when China joined the WTO, the economic growth accelerated. This economic growth also rapidly increased the demand for almost every kind of metal. In particular the demand for copper in China is considered to be one of the main factors driving the world copper price in recent years. The recent economic growth rate in China has continued to stay above 10%, and the demand for copper is high too. However, copper consumption shows regional characteristics, that is, copper is not consumed uniformly across this large country that has a huge population of nearly 1.3 billion. In this paper, the demand for copper in China was analyzed in consideration of regional differences. First, the overall consumption of copper in China was surveyed as compared with other important copper consuming countries. Next, by using regression analysis, regional future demands were estimated by the territory of China into 6 large divisions. Finally, future regional trends of copper demand were projected on the basis of these estimations. It was estimated that industrial production will increase copper consumption future in the industrial areas, while copper consumption in buildings will not increase as much in either rural or urban areas.
The rise in demand for coal due to growth in Asia is inducing coal price increases and it will be necessary to develop cleaning method for difficult-to-treat coal. High-efficiency power generation techniques are required to reduce greenhouse gas emissions and it is necessary to reduce ash content of coal significantly before combustion. Advanced coal cleaning techniques can generate low ash coals and this paper reviews recent applications of low ash coal, recent developments in commercial scale and lab scale flotation, and research results of enhanced gravity separators and comminution.
Fly ash is a by-product in coal power plants and a rich source of hollow and spherical particles. Hollow and spherical particles having density less than 1 g/cm3 are known as cenospheres. Their concentration in coal fly ash is around 1%. Particles are widely used as fillers and insulators with high performances in rubber, plastics, oil industry, space industry, glass steels, etc. due to their shape, specific surface, excellent physical and chemical properties; as a consequence, their value is relatively high. However, hollow and spherical particles are filled up with N2 and/or CO2 gas bubbles so their densities can vary from 0.6g/cm3 to near or greater than 2.0 g/cm3. Fly ash can consist of more than 80% hollow and spherical particles having particle diameter less than several hundred μm and density less than 2.0 g/cm3, but there is no efficient and economic way to selectively recover them. The authors study on the recovery of cenospheres and hollow and spherical particles having density more than 1 g/cm3 from coal fly ash using a two-inch hydrocyclone and laboratory/pilot scale Mozley multi-gravity separator(MGS). A two-inch hydrocylone having 6.4 mm of spigot diameter was used to effectively concentrate cenospheres in overflow product. A very small amount of cenospheres having density less than 1 g/cm3 were recovered as a float of overflow product. Underflow product and overflow product without cenospheres were supplied to MGS and the influence of MGS parameter such as drum rotation speed and wash water rate was studied. As a result, 54% of hollow and sphercal particles having 2.08 g/cm3 of density and 61.6 μm of median diameter in underflow product was recovered as MGS lighter product and 17% of hollow and sphercal particles having 2.19 g/cm3 of density and 8.4 μm of median diameter in overflow product was recovered as MGS lighter product. These results show that hollow and spherical particles having median diameter less than one hundred μm with middle density can be recoverd.
Indian economic growth is significant and real rate of economic growth continues 9% for several years. UN predicts that the population of India will outstrip China in 2030. Coal resources are placed more expectations on in rapid increase of demand for energy. On the one hand, Indian coal is characteristic having normally high ash content and difficulty of coal separation. This report introduces coal demand and supply, coal field, issues of coal utilization, road map and present movement of CCT, specialty of Indian coal and issues of coal preparation technology through JCOAL's study carried out more than 5 years.
The feasibility of extracting gas from the coal seam while storing carbon dioxide underground in Japan was evaluated. A CO2-ECBM project had begun near the town of Yubari on the island of Hokkaido in northern Japan. The primary coal seam of interest was 5-6m thick Yubari coal seam located at the depth of 900m. A micro-pilot and two multi-wells CO2 injection tests, involving an injection and production wells, were carried out in the period between May 2004 and October 2007. There were a variety of tests conducted in the injection well, including an initial water-injection falloff test and series of CO2 injection and falloff tests. Although gas production was obviously enhanced by CO2 njection, water production was not clearly affected by CO2 injection. Several injection tests suggested that injectivity of CO2 into the virgin coal seam saturated with water was eventually increased as the water saturation near the injector was decreased with the injected CO2 . It was believed that low injectivity of CO2 was caused by the reduction in permeability that swelling in coal matrix induced. So N2 flooding test was performed in 2006 to evaluate the effectiveness of N2 flooding on improving well injectivity. The N2 flooding test showed that daily CO2 injection rate was boosted, but only temporary. On the top of that, the permeability might not return after CO2 and N2 were repeatedly injected. It is likely that the matrix swelling might create a high stress zone near to the injection well.