Journal of MMIJ
Online ISSN : 1884-0450
Print ISSN : 1881-6118
ISSN-L : 1881-6118
131 巻 , 5 号
選択された号の論文の9件中1~9を表示しています
総説
  • 川﨑 了
    2015 年 131 巻 5 号 p. 155-163
    発行日: 2015/05/01
    公開日: 2016/01/01
    ジャーナル フリー
    New ground improvement technologies using microbial functions have attracted attention recently both within and outside Japan. In this review paper, an outline of the present status of ground improvement technologies using microbial functions is presented. First, the advantages of ground improvement technologies using microorganisms are described. Second, previous studies on ground cementing technologies using calcium carbonate, silica, or calcium phosphate compounds, which are biominerals and representative eco-friendly cement materials in nature, are explained after being classified into three chapters. The main conclusions of the present review are as follows: most of the previous studies used calcium carbonate as the cement material; the studies were conducted mainly in the laboratory; the techniques fall one-step short of practical use stages. Finally, studies related to the usage of waste and applied to natural beachrock formations are presented as future prospects; similar to the ground improvement technologies mentioned above, these studies may lead to unprecedented new understanding, discoveries, and development through cooperation between microbiology and geotechnical engineering fields in the future.
論文
  • 中村 紘樹, 大上 悟, 曽我部 信義, 中野 博昭
    2015 年 131 巻 5 号 p. 164-169
    発行日: 2015/05/01
    公開日: 2016/01/01
    ジャーナル フリー
    To clarify the effect of chloride ions on the deposition behavior and crystal morphology of Zn at initial stage from electrowinning solutions, the partial polarization curve, current efficiency and AC impedance for Zn deposition and the morphology and crystal orientation of deposited Zn were investigated. In solutions containing chloride ions, the partial polarization curve for Zn deposition was evidently depolarized and the polarization resistance was decreased. With increasing the concentration of chloride ions from 600 to 6000 mg/L, the degree of depolarization and decrease in polarization resistance became significantly large. On the other hand, the partial polarization curve for hydrogen evolution was almost unchanged by the presence of chloride ions. As a result, the current efficiency for Zn deposition of initial stage at current densities from 100 to 2000 A/m2 increased by 3 to 10 % with chloride ions. The crystal of Zn deposited from the solutions containing chloride ions became aggregated and large. This tendency was remarkable with increasing the concentration of chloride ions to 6000 mg/L. In Zn deposition at 500 A/m2, the orientation index of {0001} plane and the crystallite size of Zn increased a bit with chloride ions. This is attributed to the decrease in overpotential for Zn deposition with chloride ions.
小特集 石炭エネルギーの開発・利用
  • 安居 徹
    2015 年 131 巻 5 号 p. 171-176
    発行日: 2015/05/01
    公開日: 2016/01/01
    ジャーナル フリー
    Based on the New Basic Energy Plan and the Japan Growth Strategy, Coal will continue to be an important from a viewpoint of the energy mix. For future stable supply of coal, Japanese government will advance diversification of the coal supply countries improve and promote coal power generation efficiency by advancing technology development promote the coal power generation investment in developing countries.
  • 古川 博文, 中村 貴司, 冨田 新二
    2015 年 131 巻 5 号 p. 177-182
    発行日: 2015/05/01
    公開日: 2016/01/01
    ジャーナル フリー
    The world produced over 7.8 billion tonnes of coal in 2012. The world relies on coal for about 30% of the primary energy consumption and is consumed by 41% of electric power as fuel. Although the production and consumption are concentrating on China, the U.S., and India, especially China consumes about 48% of the total amount of coal produced in the world. On the other hand, in China, investment was supplied to coal industry and oversupply has occurred. In recent years, the structure of coal supply-demand, such as competition with alternative energy, rise of concern about global environment problems and the U.S. shale-gas revolution, rise of resource nationalism, a jump in oil price, a shortage of skill, and a nuclear problem, is changed dramatically.
  • 井清 武弘
    2015 年 131 巻 5 号 p. 183-188
    発行日: 2015/05/01
    公開日: 2016/01/01
    ジャーナル フリー
    Vietnamese coal industry is now increasing the production at a higher rate of around 15 percent a year that is almost double of the economic growth. Their coal production of 12 million tons in 2000 had been increased up to 48 million tons in 2011, most of which are anthracite, namely four times increase in ten years. During this time, depending ratio on underground production increased from 33% to 45% and in the near future underground production inevitably exceeds the production from open pit coal mines. In contrast with production increase, safety record has not been improved in the past 10 years, for example, fatality rate per one million tons of underground coal mine stays around one since 2003, namely, safety of underground coal mine had not improved not so much in spite of much effort of relevant people in Vietnam. From the experiences of technical advices for coal mine safety management in Vietnam for more than 10 years, the author had found five key important factors which relate to the safety management of underground coal mines, and which are (1) safety check during weekend and holidays, (2) ineffective utilization of monitored data, (3) production overemphasis mine design, (4) non-feasible coal mine safety regulations and (5) organizational structure for coal mine safety management. In this report, those five factors are introduced in concrete manner and some proposals for improvement would be discussed.
  • Le Trung Tuyen, 大賀 光太郎, 名和 豊春
    2015 年 131 巻 5 号 p. 189-194
    発行日: 2015/05/01
    公開日: 2016/01/01
    ジャーナル フリー
    坑内掘炭鉱におけるガス爆発は,重大災害につながる。ベトナムの無煙炭炭鉱においてもガス湧出は増大傾向にあり,ガスの安全管理が重要課題となってきている。この観点から開発されたモデルを用いて炭層の深度,ガス包蔵量などを変化させ炭鉱長壁切羽からのガス湧出を推定した。その結果,深部におけるガス包蔵量の多い炭層の場合,特に採炭パネルの準備ならびに採掘初期において,通常の通気では規定のガス濃度以下に希釈できない事態が発生することが推定された。この推定に関連して,ベトナムの無煙炭炭鉱で発生したガス爆発の結果についても考察を加え,それらの多くは採炭パネルの準備段階で発生しており,推定で得られた結果との相関性が確認された。
  • 笹岡 孝司, 濱中 晃弘, 島田 英樹, 松井 紀久男, 一ノ瀬 政友
    2015 年 131 巻 5 号 p. 195-202
    発行日: 2015/05/01
    公開日: 2016/01/01
    ジャーナル フリー
    The surface mining method is generally considered to be more advantageous than the underground mining method, especially in recovery, grade control, production capacity, economics, flexibility, safety and working environments. Therefore, the surface mining method is common in major coal producing countries. Most of coal is produced from open-cut mines in Indonesia. However, the conditions of their surface mines are worsening each year: The stripping ratio is approaching to the value of break even stripping ratio, the regulations of environmental protection become to be tighten, and the infrastructure for transportation of coal from inland mining areas is insufficient for such intense mining operations. To meet the demand for coal in Indonesia and the rest of the world, underground mines have to be developed in the near future. Under these circumstances, the development of underground coal mines from the toe of open-cut highwalls is being planned in several mines in Indonesia. However, if the conventional mining systems and designs introduced in US, Australia and European countries are applied, several geotechnical issues can be expected to arise due to weak geological conditions in the mines. This paper describes the conditions and geotechnical issues for underground coal mines developed from the toe of open cut highwalls in Indonesia and addresses problems associated with the weaker rock strata. From the results of on-site investigation and numerical analyses, the mechanisms of the roof fall have been clarified. It was concluded that the current roof support system is not sufficient to maintain the stability of the roadways. In order to develop an appropriate roof support design and code of practice for this mine, further data such as that for geological conditions, mechanical properties of roof rock, the behavior of rock around the roadways, etc. have to be collected and studied. Additionally, as underground water flow is a major problem in this mine, drainage systems should be introduced immediately.
  • 蘇 発強, 板倉 賢一, 出口 剛太, 大賀 光太郎, 海保 守
    2015 年 131 巻 5 号 p. 203-218
    発行日: 2015/05/01
    公開日: 2016/01/01
    ジャーナル フリー
    UCGにおいては,炭層内のき裂進展に伴う燃焼空洞の拡大と石炭の消費が重要であり,これがガス化効率や安全性 (地盤沈下,ガス漏洩等) に大きく影響する。本研究では,ガス化効率,回収エネルギーとガス化空洞の評価方法として,化学量論および化学平衡に基づく評価手法を検討した。生成ガス組成と求めたガス化反応式から,石炭の消費量,ガス生産量等を推定する方法である。また,エネルギー回収率を定義し,UCG室内モデル実験及び露天炭鉱の炭層で行った小規模現場実験の結果を評価し,リンキングの方式や注入ガス等のパラメータがガス化効率やガス化空洞の成長に与える影響を検討した。リンキングの方式として,L字,V字,同軸型のUCG実験を行い,ガス化効率の違いと,その原因を明らかにした。すなわち,リンキング型と同軸型モデルを比較すると,リンキング型UCGモデルの方が発熱量が高く,平均発熱量では,前者が10.26/11.11 MJ/m3 (室内) ,14.39 MJ/m3 (現場) であった。一方,同軸型モデル試験では,7.38/4.70 MJ/m3 (室内) と6.66 MJ/m3 (現場) と低い値であった。実験後の空洞体積の直接評価結果でも,リンキング型の方がガス化領域が拡大していることを確認した。リンキング方式の方が,炭層内にき裂を連続的に進展させやすいためと考えられる。また,エネルギー回収率の評価では,実験前後の供試体質量差から求めたエネルギー回収率と比較検討を行った。その結果,両者の誤差は約10%で,検討した手法によりエネルギー回収率や燃焼ガス化領域の石炭消費量を推定できることがわかった。以上の結果より,検討した化学量論法よる回収エネルギー評価手法は簡便で,実用的であることが明らかになった。
  • 野中 壯泰, 平島 剛, 熊谷 聡, 笹木 圭子
    2015 年 131 巻 5 号 p. 219-225
    発行日: 2015/05/01
    公開日: 2016/01/01
    ジャーナル フリー
    ロイヤング炭 (褐炭,水分約60%) の水熱処理を200℃から380℃の範囲で行った。改質炭に関して燃料特性,平衡水分,固体VACP/MAS 13C-NMR,熱分析を行った結果,高品位化が認められ,処理温度をより高く設定することで炭素量,固定炭素,燃料比,芳香族炭素指数が上昇した。300℃以上の温度で処理した場合湿度の変化に影響を受けず低い水分と高い発熱量が維持され,250℃以下の温和な条件での処理はエネルギー回収率と固体歩留まりの点で有利であった。水熱処理の際少量のアルカリを添加することで,改質炭のガス化速度を2倍以上速く出来る一方,灰分はむしろ低下させることが出来た。さらに添加量を増やすとアレニウスプロットの傾きが小さくなり,このときフェノール性水酸基が減少に転じガス化の反応パスに変化が生じたものと考えられる。
feedback
Top