資源と素材
Online ISSN : 1880-6244
Print ISSN : 0916-1740
ISSN-L : 0916-1740
116 巻, 2 号
選択された号の論文の11件中1~11を表示しています
総説
  • 井上 雅弘
    原稿種別: 総説
    専門分野: 資源開発
    2000 年 116 巻 2 号 p. 81-89
    発行日: 2000年
    公開日: 2001/09/12
    ジャーナル フリー
    The term of "ventilation network analysis" meant the calculation of airflow distribution in a ventilation network, that is the calculation of airflow rate through each roadway in a mine formerly. However, nowadays the meaning has expanded to mine fire simulation, thermal environment analysis in a mine, detection of abnormal roadways, optimization of network, etc. This paper describes these analyses first.
    The heading face is one of the most important places to be ventilated in a mine. There are still some problems remained to be analyzed about the ventilation of heading faces, especially, for the discharge of flammable gases and control of respirable dust. The latter part of the paper describes the result of analysis about the heading face ventilation using an actual size model roadway, small-scaled model roadways and computational fluid dynamics.
論文
  • 山口 勉, 大久保 誠介, マラニーニ エンリコ, 成田 孝
    原稿種別: 論文
    専門分野: 資源開発
    2000 年 116 巻 2 号 p. 91-96
    発行日: 2000年
    公開日: 2001/09/12
    ジャーナル フリー
    During a multistage creep test (MSCT), a rock specimen is stepwise loaded until failure. Several loading phases are followed by creep periods at regular time intervals, during which free viscous deformations are observed in the sample. The MSCT is very useful to examine the visco-elastic behavior of rocks : when the stationary creep state (or steady state) is observed during a creep stage, the creep rate is revealed as a function of the applied constant stress level. In case of hard rock like granite, a logarithmic creep relation is commonly identified to explain the visco-elastic behavior during a given creep stress level. One of the authors (Okubo) proposed a visco-elastic constitutive equation for a rock. This law can explain correctly the time dependent behavior of rocks, both during creep behavior, relaxation behavior, and dependence of strength level associated to different loading rates.
    In this work, MSCTs were performed in triaxial compression on Inada granite specimens, at a confining pressure varying from 0 to 40 MPa. The data were analyzed adopting the above said constitutive equation. the results of both the experimental and the analytical characterization give the following conclusions : (i) the Janach failure criteria fits correctly the strength level variations of Inada granite, at confining pressure up to 40 MPa ; (ii) a logarithmic relation can explain the creep rate during each step of the MSCTs ; (iii) the proposed constitutive equation predicts correctly the visco-elastic behavior of the rock ; (iv) the same formulation can be used to estimate the life-time dependency of this rock.
  • - 一軸引張試験結果との関係に注目した検討 -
    大久保 誠介, 福井 勝則, 荻野 智成
    原稿種別: 論文
    専門分野: 資源開発
    2000 年 116 巻 2 号 p. 97-104
    発行日: 2000年
    公開日: 2001/09/12
    ジャーナル フリー
    The study was started mainly to investigate horizontal velocity change and attenuation not only in pre-failure region but also in post-failure region. Beyond the strength failure point, ten rocks were tested in uniaxial compression and elastic-wave velocity and wave height in lateral direction were measured. Typically, the velocity and the wave height started decreasing at relatively low stress level in pre-failure region. The wave height decreased more rapidly than velocity; (Wave height change) / (Initial value of wave height) = 3 (Velocity change) / (Initial value of velocity). It was also found that the velocity and the wave height were correlated with the lateral strain which increased with crack number and length within a rock specimen.
    The experimental results in compression were compared with those in tension which had been carried out by the authors, and two interesting findings were obtained. 1) At the strength failure point of Inada granite and Akiyoshi marble, the lateral strain in uniaxial compression test was close to that in uniaxial tension test. 2) Energy loss in a loading-unloading cycle in uniaxial tension test was compared with the attenuation of elastic wave in uniaxial compression test, and a good correlation was found between the two.
  • 大久保 誠介, 福井 勝則
    原稿種別: 論文
    専門分野: 資源開発
    2000 年 116 巻 2 号 p. 105-110
    発行日: 2000年
    公開日: 2001/09/12
    ジャーナル フリー
    A non-linear rheological model which was proposed by the authors mainly for the behavior of a brittle material in compression is slightly modified and extended to tensile stress field. This constitutive equation can be applicable to the post-failure region / behavior of steel-fiber reinforced mortar in tensile stress field. The one-dimensional simulation results indicate that the stress decreases more rapidly in the post-failure region as length of a test piece increases.
    The constitutive equation is implemented to a FEM program and 4-points bending test is simulated. Calculated results of ultimate strength, absorbed energy and load-deflection curve reasonably coincide with the experimental ones.
  • 児玉 淳一, 石塚 与志雄, 安部 透, 石島 洋二, 後藤 龍彦
    原稿種別: 論文
    専門分野: 資源開発
    2000 年 116 巻 2 号 p. 111-118
    発行日: 2000年
    公開日: 2001/09/12
    ジャーナル フリー
    The effects of excitation frequency on fatigue life and fatigue damage were investigated by carrying out a series of cyclic loading tests at high stress levels on Inada granite. An attempt was made to estimate fatigue strength under long-period loading based on the experimental results. The amount of fatigue damage per cycle and fatigue life decreased with increases in the excitation frequency at the same maximum stress. On the other hand, they did not depend on the excitation frequency between 2.5 × 10 - 4 Hz and 0.5 Hz when the same maximum stress ratio, which was normalized by the static strength under a strain rate corresponding to the excitation frequency, was applied. Cyclic fatigue tests at the frequency of 0.5 Hz were performed under several stress ratios. It was clarified that : (1) there is no fatigue limit within 4 × 104 cycles of loading, (2) the relationship between stress ratio S and fatigue life Nf can be represented by S = A - B log Nf (S - Nf curve), (3) fatigue strength increases with increases in confining pressure, and (4) fatigue strength decreases in the presence of water. Estimation of fatigue strength under long-period loading might be possible using both the S - Nf curve and the relationship between static strength and strain rate.
  • 張 其武, Flio James M., 二階堂 満, Kim Wantae, 齋藤 文良
    原稿種別: 論文
    専門分野: 素材
    2000 年 116 巻 2 号 p. 119-123
    発行日: 2000年
    公開日: 2001/09/12
    ジャーナル フリー
    Mixed grinding of the two sets of starting materials was conducted under atmospheric dry condition by a planetary ball mill to investigate the formation of forsterite in the sintered body. These were talc-magnesium carbonate basic (MCB) and talc-magnesium oxide powder mixtures. The specific surface area of the ground product increases in the initial stage, subsequently it decreases due to aggregation of the obtained fine particles. The grinding the mixture of talc and (MCB) causes structural change into amorphization, while crystalline phases still remain in the ground mixture of talc and MgO. This amorphization in the former mixture resuls in the formation of forsterite single phase at lower temperature than that of the unground one as well as that of the latter one. The addition of methanol and regrinding of the mixture induce lowering of sintering temperature by about 100 K in the formation of forsterite single phase.
  • -とくに反応を伴う一次元拡散過程の場合 -
    定木 淳, 岡野 靖彦
    原稿種別: 論文
    専門分野: 鉱物処理
    2000 年 116 巻 2 号 p. 124-130
    発行日: 2000年
    公開日: 2001/09/12
    ジャーナル フリー
    Transfer function representations of various plants still have significant positions in design and analysis of control systems, because new frequency-domain control techniques, such as H control theory, are now easily available. This paper describes applications of transfer function representations of resources processing plants. The authors at first have showed examples of processes when the idea proposed in a paper of Åström et al. (1992) is applied to resources processing plants.
    The authors have, subsequently, calculated 4 transfer functions of one-dimensional reactive-diffusive models, which are typically found in resources processing plants, under 4 types of boundary conditions. Then, behaviors under Bo → ∞, 0 have been established based on the transfer functions calculated above. The transfer function representation of a free-flow flotation process proposed by Niemi (1966) seems to be lack of generality, because of the boundary conditions adopted. The authors have showed a new transfer function representation of the flotation process, under appropriate boundary conditions. The new transfer function model has been investigated to validate the idea of Åström et al. (1992), which attempts to apply Ziegler Nichols's PID tuning method through analyzing dimensionless numbers. The main results are summarized as follows :
    · Achievable performance of the PID control system is not affected by normalized reaction constant K, but by Bodenstein number Bo.
    · Relation between normalized process gain κ and normalized deadtime θ can empirically be described by an equation κ = 1 + 0.46 / θ 1.67. Relation κ = 2 (11 θ + 13) / (37 θ - 4) for finite-dimensional systems also gives rather a good approximation.
    · Within recommended region 0.1< θ < 0.6 of Ziegler-Nichols's ultimate gain method, crude approximations κ λ ≈ 1.4 and τ ≈ 1 hold.
    The latter half of the second term and the whole of the third term mentioned above show the validity of the idea of Åström et al. (1992), while the reactive-diffusive models are infinite-dimensional. This suggests usefulness of dimensionless numbers.
    Relations between other tuning methods and dimensionless numbers, applications to back-mixing models which are also familiar models in resources processing plants are the remaining themes to be studied.
  • 別所 昌彦, 和嶋 隆昌, 中澤 克仁, 西山 孝
    原稿種別: 論文
    専門分野: 資源探査
    2000 年 116 巻 2 号 p. 131-135
    発行日: 2000年
    公開日: 2001/09/12
    ジャーナル フリー
    In a geothermal power station, silica scale often causes serious problems, such as a decline of the heat exchanger's performance, and plugging of pipelines and permeable layers. Polymerization of silicic acid dissolved in geothermal water plays an important role in silica scale formation, and this reaction is affected by many factors, such as temperature, pH, silica concentration and coexisting elements. In this study, the effect of residence time, temperature, aluminum concentration, and pH on silica precipitation was investigated to resolve silica scale troubles. The experimental results were as follows : Polymerization of silicic acid supersaturated in geothermal water progressed by decreasing temperature and increasing residence time. The aggregation through the formation of Si-O ···Al 3+ ···O-Si bonds occurred in the narrow pH range between 4 and 5. A large quantity of silica precipitation formed by adding trace amounts of aluminum. We present a new process of silica removal from geothermal water based on the optimum conditions obtained by experiments.
  • 張 其武, 盧 金鳳, 齋藤 文良
    原稿種別: 論文
    専門分野: その他
    2000 年 116 巻 2 号 p. 137-140
    発行日: 2000年
    公開日: 2001/09/12
    ジャーナル フリー
    Fluorescent powder was subjected to mechanochemical (MC) treatment using a planetary mill to control its structural change followed by selective leaching of Y and Eu with 1N HCl solution at room temperature. The crystal structure of the fluorescent powder tends to be transferred into disordered state by the MC treatment. It is possible to control the crystal disordered state by choosing the MC condition such as media size and rotational speed of the mill. The optimum condition gives us to improve the yield of Y and Eu, depressing the yield of La, Ce and Tb in the acid leaching. In the present experiment using 15 mm ball size, the preferable MC treatment would be conducted within about 20 minutes at 400rpm in mill rotational speed.
  • - フェロニッケル製錬に関する基礎的研究(第3報) -
    松森 豊己, 石塚 司
    原稿種別: 論文
    専門分野: 製錬
    2000 年 116 巻 2 号 p. 141-146
    発行日: 2000年
    公開日: 2001/09/12
    ジャーナル フリー
    Gangue minerals of siliceous nickel ores, raw material of Fe-Ni smelting, occupy some 80 % of each ore and changes of the mineral compositions of blended ores due to mines as well as working places are apt to make smelting operations unsteady. The effect of the mineral compositions and flux on softening temperatures of the ores was investigated and the following results were obtained.
    (1) Fe2SiO4 inevitably formed in reducing process of the ore creates olivine slag with low melting point, reacting with CaO, Al2O3 and SiO2 of the flux as well as the ore and generates local molten phases above some 1,473K.
    (2) Melting temperature of the ore is influenced in the beginning by the amount of Fe2SiO4, that is index of Fe / SiO2 and later by index of (Al2O3 + CaO) / SiO2, along with proceeding of FeO reduction.
    (3) The ore with higher value of Fe / SiO2 gives better reduction fractions of Ni and Fe due to progress of direct reduction by solid C in the local molten phases from lower temperature.
    (4) Fe of goethite plays essential roles both in slag formation and in Ni recovery.
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