Asaue H.,Kumamoto University |
Sasahara M.,Toda Corporation |
Yoshinaga T.,Kumamoto University |
Obara Y.,Kumamoto University |
And 2 more authors.
Acta Geodynamica et Geomaterialia | Year: 2013
Magnetotelluric (MT) and audio-magnetotelluric (AMT) methods were applied to clarify the deep geological structure in a coal-mining area in Kushiro, southeastern Hokkaido, Japan. These methods are effective in surveying to deep. Onedimensional inversion was applied to the measurement data obtained in the MT and AMT surveys to estimate the resistivity distributions in the study area. In addition, the one-dimensional inversion method was improved to obtain accurate results by including a smoothing factor and Akaike's Bayesian information criterion. The inversion method revealed that the lowresistivity zones at depths between 100 and 120 m below sea level correspond with the Yubetsu coal-bearing formation and clay layer, and the thickness of Cretaceous strata was estimated to be more than 4000 m. Finally, the dip of the Osotsunai fault was estimated.
Tamamura S.,Hokkaido University of Science |
Ueno A.,Hokkaido University of Science |
Aramaki N.,Hokkaido University of Science |
Matsumoto H.,Kushiro Coal Mine Co. |
And 3 more authors.
Organic Geochemistry | Year: 2015
The effect of oxidative weathering on the composition of sedimentary organic matter (SOM) of lignite, subbituminous coal, quartzose arenite, siliceous mudstone, siliceous shale and diatomaceous shale was investigated in Hokkaido, Japan, in a subarctic humid climate. For 15 samples in total, a humic substance extraction method was applied to divide SOM into lipid-C, humin-C and alkali soluble-C. The alkali soluble-C was further divided into fulvic acid (FA)-C, humic acid (HA)-C and a smaller molecular size fraction (SMSF)-C, which comprised organic molecules able to pass through a dialysis membrane (<1000Da) during the HA and FA purification processes. The alkali soluble-C (8-750g/kg) increased with the degree of sample weathering in compensation for lowering of humin-C. For the alkali soluble-C, HA-C (undetectable to 698g/kg) became dominant with sample weathering, in contrast to FA-C and SMSF-C. These observations imply that oxidative weathering converts humin-C into alkali soluble-C (mainly HA-C). The 13C nuclear magnetic resonance (NMR) analysis (precision ±2.4%) revealed higher aromatic-C content of HA (average 40%) as compared to bulk humin (average 33%), suggesting that the re-generated HA was derived from condensed products (aromatic-C rich) in the humin, rather than from recalcitrant biomolecules (alkyl-C rich) in that fraction. The longer emission wavelength of the HA and FA from weathered samples in the excitation-emission matrix (EEM) spectra (precision ±1.0%) is ascribed to the abundance of oxidized aromatic moieties, with the higher O/C atomic ratio of HA and FA from the weathered samples. © 2015 Elsevier Ltd.
Widiatmojo A.,Kyushu University |
Sasaki K.,Kyushu University |
Sugai Y.,Kyushu University |
Suzuki Y.,Kushiro Coal Mine Co. |
And 3 more authors.
Process Safety and Environmental Protection | Year: 2015
The environmental safety of an underground mine depends strongly on its ventilation system. An efficient ventilation system provides fresh air, removes hazardous gases and dust, and maintains the temperature and humidity at appropriate levels. One of the most important factors in removing hazardous gases and dust is the dispersion behaviour in the mine network. This factor determines the longitudinal spreading and the average air residence time of gases or particulate matter throughout the mine. This paper describes tracer gas measurement in an underground mine and the utilisation and analysis of the dispersion characteristics using numerical simulations. The concentration-time curve obtained from the measurement is simulated to evaluate the effective diffusion coefficient that reflects the general dispersion characteristic of an entire mine. The evaluated values of effective diffusion coefficient are then compared to other data from several studies. The diffusivities obtained in this study were higher than other analytical and empirical results. More research is still required to identify the main factors causing such higher diffusivities. However, the results from the present work can be an important standpoint for future work. Numerical simulation conducted in this research was confirmed to be effective in detecting several leakage paths occurring in the mine ventilation network. © 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.