著者

岩野 圭太 永江 純一 福井 勝則 羽柴 公博

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.133, no.6, pp.123-131, 2017-06-01 (Released:2017-06-19)

参考文献数

24

被引用文献数

1

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Although blasting is a quite efficient and economical excavation method, it is rarely applied to tunnel projects close to residential areas due to its environmental impacts, especially with regard to vibration and noise. Two key controls used to mitigate the occurrence of noise and vibration due to blasting are the use of small instantaneous explosives charges and the use of precise delay times to initiate the blast design sequence. An advanced electronic detonator, which has its precision of 0.01% of designed delay time and has made it possible to achieve precise initiation control in blasting, was introduced and used in a tunnel construction site in Japan. Testing of the delay times during blasting was carried out, the test results revealed the specific features and performance of the detonator to control the blasting vibration especially within a short distance of the tunnel face. In previous studies, several ways of simulating blasting waveforms were used. One of these, the Monte Carlo method, in which the production wave was reproduced by superposing a single wave had the potential to give good predictions of the production waves that might occur. Therefore, in this study, a similar way of simulating production waves was carried out. Section peaks in the production waveforms correspond with the detonation of each blasthole. These section peaks were found to follow the Weibull distribution, even though the section peaks might be influenced by amount of explosives, drill alignment, and geological inhomogeneity etc. More detailed simulation with consideration of difference in travel time and the change of the Weibull parameters with distance gives further precise results compared with the real production waves. This study leads more precise method of predicting production waves and of optimum blasting design.

著者

制野 友樹 蟹江 澄志 村松 淳司

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.133, no.6, pp.116-122, 2017-06-01 (Released:2017-06-12)

参考文献数

43

被引用文献数

2

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Cerium-doped barium zirconate (Ce-doped BaZrO3) fine particles with high crystallinity was prepared by a hydrothermal reaction using barium hydroxide, CeCl3, and a Zr-triethanolamine complex. Characterization of the Ce-doped BaZrO3 particles revealed that utilization of the water-stable Zr-triethanolamine complex was an efficient way to introduce cerium ions into the BaZrO3 perovskite crystal structure. The three-way catalytic activity of the Ce-doped BaZrO3 for an exhaust gas conversion reaction was investigated under a stoichiometric condition (CO 0.5%, C3H6 400 ppm, NO 500 ppm, O2 0.49%, H2 0.17%, CO2 14%, H2O 10% in N2). The Ce-doped BaZrO3 exhibited a remarkable low temperature NOx cleaning performance when the Ce-doped BaZrO3 was applied as an alternative for an Al2O3 support.

著者

片岡 みなみ 包 添書 羽柴 公博 福井 勝則

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.133, no.6, pp.107-115, 2017-06-01 (Released:2017-06-06)

参考文献数

28

被引用文献数

3

---

The effect of water on the mechanical properties of rocks, such as strength and Young's modulus, has been investigated in many studies. To understand the mechanism of the effect of water on the mechanical behavior of rocks, not only these mechanical properties but also the stress-strain curve, which is one of the most basic data showing the mechanical behavior, should be focused on, and the change of the stress-strain curve with the different water conditions is needed to be known. In this study, the effect of water saturation on the uniaxial compressive strength and the stress-strain curve of rocks was investigated. The uniaxial compression test with alternating loading rate was performed using Sanjome andesite, Tage tuff, Kimachi sandstone and Akiyoshi marble. Inada granite was used for the uniaxial compression test with constant loading rate. The tests were conducted under various water conditions: oven-dried, vacuum-dried, air-dried, air-dried for one day, immersed in water and watersaturated conditions. The test results showed that the stress-strain curve of the andesite, tuff, sandstone and granite changed with the water saturation. On the other hand, the effect of water saturation on the stress-strain curve of the marble was not observed. From the test results, the increase in strength due to decrease in water saturation was discussed. A shift of the peak strength point with the water condition change was investigated, and the relation between the stress-strain curves under the different water conditions was considered based on it.

著者

廣岡 知 山口 達也 渡部 利文 山本 順也 城代 邦宏 保田 尚俊 塚田 和彦 小池 克明 朝倉 俊弘

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.133, no.5, pp.98-106, 2017-05-01 (Released:2017-05-31)

参考文献数

12

---

In addition to hydrological characterization of water-sealed type underground rock caverns, their mechanical stability is constantly monitored by measuring several properties, such as earthquake-induced vibration, strain, and tilt. Among them, tilt measurement is the most accurate monitoring method for rock deformation because of the tiltmeter's high resolution of 10-9 rad, which enables the detection of minute deformations caused by earth tide, rock responses to earthquake, change in atmospheric pressure, and artificial disturbance by operation. This study aimed to correctly extract these responses from long-term tilt data measured by a high precision tiltmeter at the Kushikino station and clarify the mechanism of tilt change as a result of deformation of rock mass. Tilt changes due to a small change in the gas phase pressure at the top of the rock cavern, approximately 10 kPa pressure fluctuation, were analyzed and discussed. The gradient response due to the gas pressure change was extracted from the measurement data by BAYTAP-G, and its magnitude was identified as 2 to 8 nrad, which was almost the same tilt response magnitude observed at an issuance of stored crude oil. This tilt response to the increase in tank gas pressure was numerically confirmed to originate from minute elastic deformation of rock masses, by using finite element method. Because fluctuation of the gas phase pressure can be continuously monitored, the effectiveness of tilt measurement was proved as a minute strain sensor for deformation of the water-sealed type underground rock cavern.

著者

早野 明 板倉 賢一

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.133, no.4, pp.76-86, 2017-04-01 (Released:2017-04-29)

参考文献数

27

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Fracture mapping conducted during gallery excavation on construction projects of a large-scale underground facility is based on traditional geological techniques such as visible observations and simple measurements of fracture orientation using a clinometer. Therefore, some difficulties persist, such as securing data quality and worker safety. Three-dimensional (3D) laser scanning, which can instantly acquire point clouds representing the 3D shape of an object surface, is can be effective for resolving these difficulties. In order to confirm the applicability of the three-dimensional laser scanning to the fracture mapping on a gallery wall, this study proposes the method for obtaining attribute information from a point cloud, such as trace length and orientation, associated with the spatial distribution of fractures. In the proposed method, the two-dimensional image is generated from the point cloud to obtain the trace map. After the proposed method was applied to an approximately 50-m-long horizontal gallery excavated into the granitic rock, the reproducibility of the attribute information of fractures obtained solely from the point cloud was examined. Results show that the number of fractures extracted from the point cloud is approximately 80% of those extracted by traditional geological techniques. Although the trace length reproducibility ratio of fractures is approximately 70%, fracture orientations calculated from the point cloud compare favorably with those measured by an on-site researcher. Most fractures that were not extracted from the point cloud do not act as water-conducting fractures because they had short lengths and because they were bonded tightly. Even if the fracture data obtained from the point cloud were applied to modelling for hydrogeological analysis, the results would probably not be influenced strongly. Results of this study indicate the possibility of applying 3D laser scanning to fracture mapping.

著者

平郡 伸一 庄司 浩史 西川 勲 小林 宙 井手上 敦

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.133, no.4, pp.68-75, 2017-04-01 (Released:2017-04-29)

参考文献数

19

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Owing to the continual depletion of resources, low-grade nickel laterite ores are being treated nowadays to extract Ni. High-pressure acid leaching (HPAL) is a suitable process for treating nickel laterite ores. HPAL has the advantage of having a high extraction rate and low chemical consumption associated with the neutralization of iron; the low chemical consumption is owing to the formation of hematite precipitate in the residue. By studying the behavior of iron under pressure acid leaching, it was observed that sulfur and carbon contained in the ore decreased the redox potential and lead to Fe (II) dissolution. Iron concentration in the leached solution was decreased by oxygen rich leaching.

著者

米田 哲朗 前田 寛之

出版者

一般社団法人資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.124, no.12, pp.694-699, 2008-12-25 (Released:2011-02-15)

参考文献数

28

被引用文献数

1 4

---

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.

著者

中村 大 川口 貴之 渡邊 達也 川尻 峻三 山崎 新太郎 山下 聡

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.133, no.2, pp.4-11, 2017-02-01 (Released:2017-02-08)

参考文献数

12

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Recently it has been found that frost heave phenomena can be seen not also in soil but also in rock. It is obvious, however, that the number of researches on frost heaving in rock is much less than that of researches on frost heaving in soil. In the present research, we newly developed test equipment in which a pressure transducer is incorporated into a device for testing frost heave in rock. Frost heaving tests were performed using three types of rocks (Ohya tuff, which is soft rock with high frost susceptibility; Kimachi sandstone, which is medium-hard rock with low frost susceptibility; and Sapporo soft rock, which is non-frost-heaving soft rock) to measure the suction pressure generated in the process of frost heaving. In these tests, we obtained fairly large negative pressures for Ohya tuff and Kimachi sandstone. In mediumhard Kimachi sandstone, negative pressure was generated before frost heaving displacement started. On the other hand, negative pressure was not generated in non-frost-heaving Sapporo soft rock. Therefore we considered that frost heaving in rock might be caused by negative pressure generated in the process of frost heaving.

著者

岸本 章宏 倉満 晶子 土橋 一輝 宇田 哲也

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.132, no.12, pp.199-206, 2016-12-01 (Released:2016-12-26)

参考文献数

33

被引用文献数

3

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A new smelting process of Ti via Bi–Ti liquid alloy is proposed, which comprises reduction of TiCl4 by Bi–Mg alloy, enrichment of Ti in Bi–Ti alloys, and vacuum distillation of the alloys. In this study, the continuous reduction of TiCl4 by Bi–Mg alloys and vessel materials for the reduction step were investigated. Firstly, we demonstrated the reduction of TiCl4 by Bi–Mg alloys and the subsequent recovery of Bi–Ti liquid alloys and MgCl2 repeatedly. As the result, the alloys containing 5.2–7.4 mol% of Ti were obtained. However, it was found that the reduction rate of TiCl4 by Bi–Mg alloys is much slower than that by pure Mg because of MgCl2 layer formed on the alloys, slow mass transfer of Mg in the alloy, and small activity of Mg. For fast reduction of TiCl4, it is required to inject TiCl4 into Bi–Mg alloys. Secondly, we kept Bi–10 mol% Ti alloys in stainless steel, soft steel, and Mo crucibles at high temperatures, and measured solubility of each metal in the alloys. The solubility of Mo in the alloy at 900℃ was 220 ppm, and elution from stainless steels and soft steel was dramatically suppressed at 500℃. However, it was found that most Mo in the alloy remains in Bi9Ti8 at the segregation cell. To decrease Mo content in Ti product, it is required that the vessel is cooled to lower temperatures than 900℃ or the shorter time of contact between Mo and liquid alloys is desired.

著者

荒牧 憲隆 A.K.M. Badrul Alam 玉村 修司 上野 晃生 村上 拓馬 金子 勝比古

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.132, no.12, pp.190-198, 2016-12-01 (Released:2016-12-16)

参考文献数

23

---

Recently, the possibility of realizing a subsurface bio-reactor has been realized since microbial methanogenesis has been confirmed in diverse subsurface environments such as coalbeds or petroleum reservoirs. We propose a new gasification method for use in subsurface environments, known as the Subsurface Cultivation and Gasification (SCG). SCG was devised based on the production of biogenic methane gas in subsurface environments. This approach employed hydrogen peroxide to decompose organic matter rapidly. Conversion of organic matter from source rocks into biomethane with the help of microorganisms is expected to be highly profitable. In this study, a series of batch tests using a hydrogen peroxide (H2O2) solution were performed on lignite to estimate the potential of low-molecular-weight organic acid production. The effects of several factors on the production of low-molecular-weight organic acids have been considered, such as, concentration of H2O2, temperature, liquid-solid ratio, and specific subsurface area of lignite. It was found that the quantity of low-molecular-weight organic acids depended on temperature, liquid-solid ratio, and specific subsurface area of lignite; however, there isn't a unique relationship between them and the H2O2 concentration. Moreover, the mass of lignite reduced remarkably when batch tests were performed with a high concentration of H2O2. If H2O2 is to be injected into a target seam with the SCG method, we should estimate the optimum H2O2 concentration to produce low-molecular-weight organic acids with taking into consideration the mechanical stability of the target seam as well as the subsurface environmental chemical reaction with a geological improvement.

著者

森 勇人 高橋 弘 加来 伸夫 西村 宏之

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.132, no.12, pp.182-189, 2016-12-01 (Released:2016-12-15)

参考文献数

14

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It is difficult to reuse the construction sludge directly because the water content of it is extremely high. Therefore, it has been disposed as industrial waste in the final disposal site. In order to reduce the construction cost and environmental load, the effective reuse of construction sludge has been an important problem. In order to increase the recycling rate of construction sludge and to solve the above mentioned problem, the authors have already developed a new recycling method for construction sludge by using paper debris and cement. As this method can improve the high water content sludge into high quality ground materials on sites, this method has already been utilized in over 400 construction sites in Japan.On the other hand, the biodegradation of fibrous materials is not made clear as yet. It is considered qualitatively that fibrous materials used in this method is hard to be biodegraded by soil microbes, because fibrous materials still remains in the soil which was improved by this method 10 years ago. However, the degradation by soil microbes is not confirmed quantitatively.Therefore, the biodegradability of fibrous materials was investigated experimentally through a culture test and a soil buried test. As a result, it was found that paper fragments were degraded in the solution of pH7.0, but were not degraded in the solution of pH9.5. Furthermore, it was confirmed through soil buried test that paper fragments buried in the normal mud were degraded significantly, but those buried in Fiber-Cement-Stabilized soils were not degraded and fibrous materials remained. Therefore, it was concluded that the fibrous materials in Fiber-Cement-Stabilized soil are not degraded by soil microbes when pH of Fiber-Cement-Stabilized soil is over 9.5, and they remains in the modified soils for a long time.

著者

濱井 昂弥 小寺 拓也 小林 幹男 増田 信行 酒田 剛

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.132, no.11, pp.175-181, 2016-11-01 (Released:2016-11-25)

参考文献数

17

被引用文献数

3

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In order to prevent the mine pollution caused by the acid mine drainage (AMD) from abandoned metal mines in Japan, the treatment of AMD has been conducted with neutralization using a significant number of reagents. Passive treatment processes are attractive as an alternative because of an energy and cost saving one. Although the passive treatment processes using sulfate-reducing bacteria (SRB) have been investigated widely in the United States and Europe, many of those processes require a huge area that is necessary for a long hydraulic retention time (HRT). So, in this research, the mechanism, influential factors and performance of metal removal using SRB have been investigated in the column test to develop it as a prospective, effective and compact process. The results showed that sulfate reduction by SRB had continued for 140 days under the condition of a 50-hour HRT, and that metals had been removed as sulfides in a column. In addition, it is apparent that the positions where each metal sulfide was precipitated were different. This means that the quality of AMD is an important factor when the treatment facility is designed.

著者

Le Trung TUYEN Nhu Viet TUAN 大賀 光太郎 井清 武弘

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.132, no.11, pp.167-174, 2016-11-01 (Released:2016-11-21)

参考文献数

13

被引用文献数

5

---

無煙炭は自然発火し難いと一般的に言われてきたが,ベトナムの無煙炭炭鉱においては2004 年以降,幾つかの炭鉱において自然発火が多発するようになってきている。筆者等は,これら全ての自然発火事象の調査と対策に関わってきている。また,亜瀝青炭を採掘する一炭鉱における数回の自然発火事象についても調査を行った。本論文では無煙炭の自然発火の特性を中心に検討を行う。この中で,無煙炭の自然発火の指標ガスとして,瀝青炭などに見られる炭化水素系ガスは発生せず,一酸化炭素と水素の二種類のガスに限定されることを明らかにするとともに,自然発火防止の観点から現場の採掘条件の問題点などについても検討する。

著者

五十嵐 敏文 上田 貴宏 洞 秀幸 城 まゆみ 加藤 欣也 三代 雅崇 工藤 元

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.130, no.2_3, pp.60-64, 2014-02-01 (Released:2015-02-01)

参考文献数

11

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Horonobe Underground Research Center, located in northern Hokkaido, Japan, has been excavating shafts of underground research laboratory for R&D of radioactive waste disposal. In this site, the groundwater seepage from the shafts and leachate from the waste rock storage site contain high concentrations of total nitrogen. Ammoniumnitrogen, the major chemical species of nitrogen in the seepage and leachate, has been treated by the effluent treatment facility. However, the ammonium-nitrogen is transformed to nitrite- and nitrate-nitrogen (nitrification products) by nitrification. As a result, the concentrations of total nitrogen increase to the effluent guideline due to nitrification. Therefore, column experiments were carried out to understand the phenomena and the factors affecting the leaching behavior of nitrification products. The result showed that the nitrification was inhibited when the column layer was almost saturated, and that the nitrification occurred near the surface of waste rocks, in particular, at 25℃. These results indicate that nitrification can be mitigated by controlling the hydrological conditions in the waste rock storage site.

著者

富山 眞吾 五十嵐 敏文 井伊 博行 髙野 日出男

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.132, no.5, pp.80-88, 2016-05-01 (Released:2016-05-14)

参考文献数

30

被引用文献数

6

---

The understanding of source and flow path of the groundwater provides important strategy for the environmental management of mines. Thus, groundwater samples from the shaft and level in the Shimokawa mine and the surrounding river water samples were taken and the stable isotopes of hydrogen and oxygen and water quality of the samples were analyzed. The results indicate that shallow groundwater starts mainly from mountain-sides and passes through rocks above ore bodies. The simulation of groundwater flow was also conducted. The distribution of velocity vector of the simulated result showed that down streamlines which flows more than 2×10-3 m per day from mountain-sides to the ore bodies were observed. By considering the altitudes of mountain-sides range from 300 to 550 m, these results correspond well with the altitudes estimated from δD and δ18O values of samples.

著者

徐 維那 森本 慎一郎

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.132, no.4, pp.66-70, 2016-04-01 (Released:2016-04-29)

参考文献数

21

被引用文献数

3

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Cobalt tends to occur in the high risk regions of the world. Cobalt sources are typically concentrated in Congo, DRC, and there are concerns about supply security. Cobalt is used in the leading-edge industries including green technologies and aerospace industries. In terms of resource security, it is important to verify the domestic cobalt consumption trends. In order to resolve the domestic cobalt consumption trends in Japan in 2013, we tracked the cobalt consumption structure from material to end-uses by applying the bottom-up approach, and illustrated the recent domestic cobalt flow by using a substance flow analysis. Recent consumption in 2013 was driven primarily by the use of cobalt in Li ion batteries (7839 t) and nickel metal hydride batteries (1263 t). In total, 9413 t of cobalt was input to Japan in 2013. And also, we anticipated the future domestic cobalt demand up to 2020, based on the relationship between the historical consumption trends and GDP. It showed that cobalt demand would reach to 13162 t in 2020, that is, Li ion battery sector (11089 t) should hold the biggest demand in 2020, followed by NiMH battery sector (1004 t), carbide sector (320 t), magnet sector (360 t), etc.

著者

名木 稔

出版者

一般社団法人資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.123, no.12, pp.779-783, 2007-12-25 (Released:2010-12-17)

参考文献数

11

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In Japan, the domestic recycling system of the nonferrous metal is formed with two businesses. One is many collecting & sorting enterprises and processing & wholesale enterprises, which are usually small and medium-sized business. The other is nonferrous metal smelting & refining enterprises, which are usually big business. Recently legislative resource recycling system, which consists of Home Appliance Recycling Law, End-of-Life Vehicles Recycling Law, Law for Promotion of Effective Utilization of Resource and so on, has been also developed. But, in spite even in these circumstances, considerable amount of domestic occurrence scraps of copper has been exported to China, and a lot of used home appliances and used personal computers have been exported to foreign countries. Namely, it has become clear that the present resource recycling system could not circulate the resources sufficiently inside Japan.These problems were caused by rapidly increasing resource consumption of the world in these several years, which was originated by quick economic development of the Asian region, in especial in China. Tightness of worldwide resource demand has requested the advancement of creating new countermeasures and/or corresponding methods under the slogan of “conservation and effective utilization of resources” for a long time.This manuscript intoroduces these circumstances and suggested some solutions to the problems.

著者

田村 智樹 太田 光浩 児玉 淳一 吉田 豊

出版者

一般社団法人資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.128, no.2, pp.65-71, 2012-01-25 (Released:2013-06-26)

参考文献数

14

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Recently, old narrow tunnels are reused by widening their sections for economic efficiency. New design concept will be required in their construction because excavation damaged zone (EDZ) might be already formed around old tunnels. Especially, estimation of EDZ extent is necessary for safe construction and stability assessment of a widening tunnel. In this study, EDZ around an old tunnel constructed in the Neogene soft rock seventy years ago was estimated based on P-wave velocity and observation of the face during widening. Deformation caused by widening the old tunnel was also measured. It was found that EDZ estimated by reduction in P-wave velocity was in good agreement with that estimated by observation of the face. It was also found that deformation of the widening tunnel was much less than that of either the old tunnel or a new tunnel constructed near the widening tunnel. In the widening tunnel, most of EDZ had been excavated and non-damaged zone outer side of the EDZ had been little excavated. It can be expected that deformation of a widening tunnel is little when the section size of that is almost equal to extent of EDZ.

著者

松木 浩二 狩野 祐一 坂口 清敏 木崎 彰久

出版者

一般社団法人資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.126, no.12, pp.668-678, 2010-11-25 (Released:2011-11-25)

参考文献数

26

被引用文献数

1 1

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Using joint elements for a mechanical model of grain boundaries, we performed a preliminary 3D finite element analysis of uniaxial tensile fracture for specimen models of monomineral polycrystalline rock under the assumption that fracturing occurs only at the grain boundaries. The specimen models were created on a computer by the method previously proposed by the authors, and the constitutive law of the grain boundaries was derived by applying the associated flow rule in the plastic theory and a tension-shear-softening curve to an extended Coulomb criterion. Tensile fracturing initiates at grain boundaries with a small angle of the normal direction relative to the loading axis, which are followed by grain boundaries with a larger angle of the normal direction. Unloading of intergranular cracks occurs before the peak strength when the intergranular cracks do not compose the final failure plane that is completely formed near the inflection point of the axial stress-axial strain curve after the peak. During the completion of the final failure plane, the conversion of failure mode from tension to shear occurs at intergranular cracks that have a large angle of the normal direction relative to the loading axis. For these intergranular cracks, the axial displacement given at an end of the specimen is converted to a shear displacement, rather than an opening displacement, and the normal stress becomes to be compressive due to shear dilation. Furthermore, the number of tensile intergranular fracturing at the peak strength increases with a decrease in the constant α that characterizes the rate of decrease in the tensile strength in the tension-shear-softening curve of the grain boundaries, and as a result, the tensile strength of the rock specimen increases with a decrease in the constant α. However, the effect of the residual frictional coefficient is small and limited to the stage after the final failure plane is completely formed, since the residual friction coefficient affects the mechanical behavior of the grain boundaries only after the failure plane is completely formed.

著者

高階 浩二 中尾山 利行

出版者

The Mining and Materials Processing Institute of Japan

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.123, no.12, pp.751-753, 2007-12-25 (Released:2010-12-17)

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The Ikuno tin smelter has started its operation in 1913, followed by tin refinery in 1916. Originally, the reverberatory furnace had been used for smelting, but later it was replaced by the present electric furnace in order to improve productivity and increase tin recovery. The refinery was relocated from Ikuno to Osaka in 1920, and then again relocated to Naoshima in 1960.The present refinery in Ikuno has started operation in 1991. After Akenobe mine was closed in 1987 due to low tin price and its poor mining condition, domestic secondary materials from the market has been purchased and treated. At present, Ikuno plant is the only producer of electro-refining tin in Japan and 65t/month of electric-tin has been produced.