著者

アニンディティヨ パトモノアジ ムハンマド ナシル ムハンマド アジス マハルディカ 雲 佘 末包 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.137, no.9, pp.91-97, 2021-09-30 (Released:2021-09-30)

参考文献数

23

被引用文献数

2

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多孔質内にトラップされているガスの流動している水相への溶解は二酸化炭素地下貯留(GCS)などの様々な水理学的分野において重要な過程である。GCS では,CO2 の溶解により,貯留層圧力変化や浮力によるリークリスクの低減につながるため溶解速度は安全性評価において重要な観点になる。本研究ではCO2, O2, N2, と Ar の4種のガスの多孔質中での溶解プロセスの違いを比較検討した。CO2 は他のガスに比べて極めて特徴的な溶解挙動を示すことを見出した。CO2 は他のガスに比べて溶解度が一桁程度大きいため,初期の溶解が非常に速く,トラップされたCO2 気 泡の周りに飽和水の膜が形成される。この飽和膜の存在がCO2 の物質輸送係数を低下させていると考えられる。

著者

西松 裕一

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.129, no.1, pp.1-10, 2013-01-01 (Released:2014-01-30)

参考文献数

16

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In This paper, the author tries to discuss on the development and finiteness of natural resources on the basis of the present state of their supply and demand.The natural resources are classified into several categories i.e. mineral resource as solid raw materials, fossil fuels, nuclear power and new natural resource of energy.The finiteness and exhaustion of natural resources are one of the most important problems, in near future, because they are indispensable for production of various industrial materials as well as fuel of power plants, industrial plants, transport facilities, and home use.Then, the effect of increasing concentration of CO2 on the global warming is critically discussed from scientific and long term point of view. Furthermore, it is indicated that the nuclear power is one of the most important energy resources in the future, although there remain some severe technical problems to be solved, at present. Next, the author discuss on the technical features and possibilities of such new natural energy resources as solar panel, wind power plant, geothermal energy, etc.And, the features of various storage facilities of electric power are discussed from technical and ecological point of view, because most of new natural energy are transformed into electric power for transmission and tentative storage.Finally, the author indicates that is most important to discuss on the interaction amongst new natural energy, mineral resources, and global environment from scientific and long term point of view.

著者

Dagvadorj Otgonjargal 中村大 川口貴之 渡邊達也 川尻峻三 宗岡寿美

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.137, no.7, pp.69-78, 2021-07-31 (Released:2021-07-31)

参考文献数

16

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In this study,field surveys were carried out at the damaged area of slope stabilization works,where the main cause was presumed to be the frost heaving of the rock mass.Field measurements of the freezing depth and the amount of frost heave were also conducted.In addition, the effectiveness of the slope stabilization work with the frost heave measures was verified based on the investigation results.The findings are summarized as follows. (1) From the results of the field survey and the field measurements,it was found that even if frost heaving occurred in the extreme surface layer, the rock mass would be degraded and the slope stabilization work would be affected.(2)From the results of the frost heaving tests, it is clear that the frost susceptibility of the damaged rock slope is extremely high, and there was wide agreement between the results of the frost heaving tests and the results of determining the frost susceptibility of the damaged rock slope using a simple strength test method. Therefore, the validity of the simple method proposed by Nakamura et al. for determining the frost susceptibility of rocks by using the strength test was also verified. (3)It was confirmed that both the gabion and the continuous fiber reinforced soil work were effective in preventing the freezing front from advancing into the rock mass.The method of covering the rock slope with non-frost susceptible material to prevent the penetration of the freezing front was found to be effective as a countermeasure against frost heaving.

著者

藤井 響也 武部 博倫

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.137, no.6, pp.63-68, 2021-06-30 (Released:2021-06-30)

参考文献数

19

被引用文献数

3

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Mixtures of copper concentrate and silica sand with various CuFeS2/FeS2 ratios and with 5 mg in weight were dropped from the top side of the silica tube filled with O2 gas and were reacted at 470℃. The Fe/SiO2 mass ratio of the mixtures was fixed at 1.1 as a typical composition of flash smelting. The samples exhibited the white light emission expecting the arrival temperature of > 1500℃ due to the ignition reaction of sulfide minerals. Reaction products were evaluated by using scanning electron micrograph-energy dispersive X-ray spectrometry (SEM-EDS) analysis. In addition to un-reacted oxide and sulfide particles, matte-slag-mineral-magnetite coexisted particles were recognized in microstructure observation. The products supported heterogeneous reactions occurring in the copper concentrate burner. The effect of FeS2 concentration on copper concentration in matte phase and magnetite phase fraction in slag phase was discussed.

著者

張 春偉 高 謙 胡 映学 袁 正一 末包 哲也 肖 鋒

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.137, no.5, pp.56-62, 2021-05-31 (Released:2021-05-27)

参考文献数

30

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多孔質中の非混和二相流に関する現象はCO2地下貯留や原油増進回収,土壌修復など様々な工業的,自然科学的応用を有している。ハイネスジャンプや毛管圧浸透などの空隙スケールの現象は置換プロセスに大きな影響を与えることが知られている。ハイネスジャンプは周囲の空隙内におけるメニスカスの再配置を伴いながら二相界面が急激に移動する現象である。対して,毛管圧浸透は濡れにくい相が大きな空隙を平坦な界面を維持しながら選択的に浸透する現象である。本研究では,様々なスロート径を有するランダムな構造を有する多孔質における排水過程の数値シミュレーションを行った。ハイネスジャンプと毛管圧浸透は飽和率の変化に影響を与える。ハイネスジャンプでは飽和率が変わらず先端界面の移動が生じる。一方,毛管圧浸透では先端位置がほとんど変化せず,飽和率の上昇が発生する。さらに,キャピラリー数と粘性比の影響を調べた。高いキャピラリー数と高い粘性比が,CO2などの濡れにくい相のキャピラリートラップには有効である。エネルギー収支を求めた結果,外からなされた仕事の48%がこれらの不可逆過程で散逸していることが分かった。

著者

荒牧 憲隆 村上 拓馬

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.137, no.5, pp.51-55, 2021-05-31 (Released:2021-05-27)

参考文献数

9

被引用文献数

1

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We proposed a new gasification method that converts unused organic matter in sedimentary rocks to bio methane gas through the use of microorganisms, known as Subsurface Cultivation and Gasification (SCG). Our approach uses hydrogen peroxide (H2O2) to decompose organic matter rapidly into usable substrates for methanogens. We previously reported that H2O2 would be useful for effective SCG at lignite, and conversion of organic matter from lignite into biogenic methane with the help of microorganisms is expected to be highly profitable. However, changes of physical properties of the sedimentary rock seem to occur due to decomposition of sedimentary rock in the biogenic methane conversion with the SCG method. In this study, immersion tests using a H2O2 solution were performed on two types of lignite to estimate the quantity of low-molecular-weight organic acids and the producing potential for biogenic methane gas. In addition, mass loss rate of lignite with oxidative decomposition of lignite was examined. The mass loss of lignite with the oxidative decomposition increased with increasing the amount of substance in H2O2. Furthermore, it was confirmed that the loss rate depends on the lignite. The biomethane deposits might become mechanically unstable during promoting decomposition of organic matter of lignite seams, if lignite has the greater resource potential for biomethane.

著者

尾﨑 佳智 岡部 徹 香川 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.130, no.4, pp.93-103, 2014-04-01 (Released:2015-04-01)

参考文献数

22

被引用文献数

3 10

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Nickel is widely used because of its excellent physical and chemical properties. Stainless steel and super alloys for turbine blades are representative nickel-based alloys. It is noteworthy that nickel has recently been adopted for use as a component of electronic devices such as capacitors and secondary batteries. Nickel is indispensable in our day-to-day life, and it is widely used in basic to advanced applications. A future shortage of nickel is anticipated because the demand for this metal in developing countries in places like BRICs and Southeast Asia is rapidly increasing along with their economic growth. There are two kinds of nickel ore: sulfide ore and oxide ore. Sulfide ore is mainly used because of its ease of concentration and smelting. Oxide ore, which is not as useful at this stage, should be considered as a potential new source of nickel for the future since it contains 70% of nickel resources. This paper reviews the current status of the resources and supply–demand of nickel as well as its metallurgical processing. An update and outlook on hydrometallurgical process technologies for nickel laterite ore, especially the HPAL process, which will be widely applied because of its high efficiency, are introduced.

著者

徂徠 正夫 後藤 宏樹 杉原 光彦 西 祐司 中尾 信典

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.137, no.4, pp.46-50, 2021-04-30 (Released:2021-04-28)

参考文献数

17

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Toward the implementation of geological CO2 storage, cost reduction of CO2 monitoring during and after injection into targeted reservoirs is the key issue. The continuous gravity measurement using a superconducting gravimeter, which has been applied to the demonstration project site in Japan ahead of the rest of the world, has a potential to resolve the issue from the viewpoint of a complement to the high-cost seismic survey. The concept is such that the continuous gravity measurement is substituted for constant monitoring and that the use of seismic survey could be limited only when any anomaly is detected. The comparison of the monitoring cost after the completion of CO2 injection indicated that applying gravity measurement can reduce costs by up to 15 to 50% of the seismic cost. The current detection limit of gravity change is around 1 μGal based on the application result in the coastal area in Japan. However, the time series analysis using pseudo gravity data suggested the possibility of anomaly detection even below the detection limit. Further improvement of analysis precision would lead not only to more rapid and more reliable anomaly detection but also to contribution to the cost reduction during the CO2 injection period.

著者

竹田 修 岡部 徹

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.137, no.3, pp.36-44, 2021-03-31 (Released:2021-03-27)

参考文献数

64

被引用文献数

4

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Scandium possesses unique physical and chemical properties. However, its applications are limited to special/minor fields because of its small production volume and high production cost. While the abundance of scandium in the Earth's crust is not scarce, there are no concentrated ore deposits that are commercially available. Historically, scandium was extracted as a byproduct of uranium and rare earth deposits, and smelted in a small scale. In this review, the characteristics and applications of scandium are briefly introduced. Further, the natural sources of scandium and its current resource developments are discussed. Recent technological developments in the hydrometallurgical process of nickel smelting and the resource potential of scandium from lateritic nickel deposits are also explored. With respect to the production of scandium metal, the development of reduction processes including the electrolytic and the metallothermic reactions is discussed. Finally, the reduction processes for the direct production of aluminum-scandium master alloys are also reviewed.

著者

孙 强 佐々木 久郎 菅井 裕一 ンゲレ ロナルド

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.137, no.1, pp.17-23, 2021-01-31 (Released:2021-01-29)

参考文献数

25

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In this study, pressure response at A monitoring well in early stage of CO2 geological storage were predicted against pressure build-up at CO2 injector after starting CO2 injection into a deep saline aquifer to design the monitoring well distance from the injector and resolution or sensitivity of a pressure transmitter installed in the monitoring well. The numerical simulations on pressure distributions and expanding CO2 plume front were carried out using a reservoir simulator, CMG-STARS, for the aquifer (10 km in radius, 50m in height) with open boundary under 1,000 m from the ground or seabed level. The ratio of pressure response at the monitoring well against the pressure build-up at the injector have been presented for various monitoring locations (500 to 5,000 m from a injector) and homogeneous and heterogeneous models of horizontal permeability distribution in the aquifer (Base Model and Model 1, 2 & 3) and CO2 injection patters during 100 days (Scheme 1, 2 & 3). It has been presented from the numerical simulation results that the monitoring well radial distance from the injector is recommended to be 2,000 to 4,000 m or less than 1000 m when the resolution or sensitivity of the pressure transmitter is 1kPa or 10kPa, respectively.

著者

熊本 和宏 國友 美信 岸本 章宏 岡本 克文 倉満 晶子 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.137, no.1, pp.10-16, 2021-01-31 (Released:2021-01-29)

参考文献数

31

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A new Ti smelting process via. Bi–Ti alloy is proposed. This process comprises reduction of TiCl4 to Bi–10 mol%Ti alloy by Bi–Mg alloy, precipitation of Ti-rich compound from the alloy, and vacuum distillation. In this study, we investigated the precipitation and distillation processes. In the precipitation process, the Bi–10 mol%Ti liquid alloy is cooled from 900 ℃ to 500 ℃ to precipitate Bi9Ti8 in the liquid alloy. The Bi9Ti8 is recovered by a two-step separation method: recovery of mixture of Bi9Ti8 and Bi and further removal of Bi by centrifugal filtration. We demonstrated the recovery of mixture. As the results, Ti concentration in the mixture was 31 mol%, and the Ti yield was about 45 %. Because the remained liquid alloy after the recovery contains a large amount of Bi9Ti8, it is required to reuse the remained alloy in the precipitation process. Assuming the reuse of remained alloy, the material flow of the process was designed based on the experimental results. The centrifugal filtration of the mixture of Bi9Ti8 and Bi was also carried out at 500 ℃. By the centrifugal filtration at 50 G, alloys with a size of 1.5 mm were obtained, and the Ti concentration in the alloys was increased from 31 mol% to 40 mol%. Vacuum distillation of alloy powder and ingot was demonstrated. The distillation rate was enhanced when using the powder than when using alloy ingot as a starting material.

著者

岡田 夏男 前川 陽平 大和田 済熙 芳賀 一寿 柴山 敦 川村 洋平

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.137, no.1, pp.1-9, 2021-01-31 (Released:2021-01-29)

参考文献数

10

被引用文献数

3

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Currently, there have been issues concerning the depletion and scarcity of mineral resources. This is mostly due to the excavation of high grade minerals having already occurred years and years ago, hence forcing the mining industry to opt for the production and optimization of lower grade minerals. This however brings about a plethora of problems, many of which economic, stemming from the purification of those low grade minerals in various stages required for mineral processing. In order to reduce costs and aid in the optimization of the mining stream, this study, introduces an automatic mineral identification system which combines the predictive abilities of deep learning with the excellent resolution of hyperspectral imaging, for pre-stage of mineral processing. These technologies were used to identify and classify high grade arsenic (As) bearing minerals from their low grade mineral counterparts non-destructively. Most of this ability to perform such tasks comes from the highly versatile machine learning model which employs deep learning as a means to classify minerals for mineral processing. Experimental results supported this statement as the model was able to achieve an over 90% accuracy in the prediction of As-bearing minerals, hence, one could conclude that this system has the potential to be employed in the mining industry as it achieves modern day system requirements such as high accuracy, speed, economic, userfriendly and automatic mineral identification.

著者

山路 法宏 岡本 信行 塩川 智 川野 誠矢 櫻井 宏信

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.135, no.6, pp.42-51, 2019-06-30 (Released:2019-06-28)

参考文献数

10

被引用文献数

3 9

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Seafloor Polymetallic Sulphides (PMS) is deep sea mineral that is confirmed to exist within Japanese exclusive economic zones and expected to develop as a new supply source for Japan. However, deep sea minerals including PMS have not been commercially developed so far, although various countries are eagerly working it. Japan Oil, Gas and Metals National Corporation (JOGMEC) has been commissioned by Ministry of Economy, Trade and Industry (METI) to conduct practical study on PMS for commercialization. As part of the efforts, JOGMEC implemented “Excavating and Ore-lifting Pilot Test” from the middle of August to end of September 2017. In the test, JOGMEC succeeded in consecutive lifting of ore and sea water in a state of solid-liquid flow from a depth of approximately 1,600m for the first time in the world. Through the test, it became clear that there are still many technical challenges left to be resolved for development of PMS such as improvement in durability of equipment, system optimization, adjustability of ore grain size and slurry concentration and so on. JOGMEC will continue efforts aimed at commercialization of PMS from a long-term perspective.

著者

坂田 章吉

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.136, no.12, pp.159-172, 2020-12-31 (Released:2020-12-25)

参考文献数

38

被引用文献数

1

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Since multi-national oil development companies (herein after referred to as “companies”) employ significant CSR in the Federal Republic of Nigeria (herein after referred to as “Nigeria”), CSR in Nigeria is examined in this study. CSR has changed from only pursuing a “corporate objective”, which aims to achieve companies' stable operations, to emphasizing a “development objective” through which the “corporate objective” could still be achieved. However, it has been suggested that the “development objective” oriented CSR has not always been effective because companies had a tendency to emphasize the “corporate objective”, and the “development objective” was often incompatible with the “corporate objective”. Also, it has been suggested that government failure in its community development increased the people's expectation of companies to provide community development and that community development by CSR might ease the pressure on the government to undertake a developmental role. This study examines these points and the results are as follows. Since some CSR cases were found to have achieved both the “development objective” and the “corporate objective” simultaneously, it is possible that these objectives can be achieved in concert. Many of the people who expected community development by companies responded that companies had a responsibility to pay compensation for oil extraction from the Niger Delta/Nigeria, some responded that companies had social responsibility, and a few responded that companies may have been able to provide effective community development for their CSR. Furthermore, it has been inferred that companies were expected to pay compensation even though they payed taxes to the government, because the government provided only limited community development using these tax receipts. Thus, it appears that, expectation of compensation for oil extraction by companies and their social responsibility, as well as limited community development by the government, are the major factors that could increase the people's expectation of companies to provide community development and ease the pressure on the government.

著者

加藤 達也 福島 諒 佐藤 康市 山縣 三郎 所 千晴

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.136, no.12, pp.151-158, 2020-12-31 (Released:2020-12-25)

参考文献数

51

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The objective of this study is to clarify the zinc removal mechanism and construct a quantitative model for column experiments using a natural component of organic soils, namely leaf mold. We performed column experiments using actual acid mine drainage (AMD) at several conditions. After column experiments, the residues in the column were analyzed by x-ray absorption fine structure (XAFS) analysis. These experimental results highlighted that when leaf mold, limestone, and iron powder were filled in the column, the zinc removal mechanism was not only surface complexation for leaf mold but also the formation of zinc sulfide. Whereas, when only leaf mold was filled in the column, that was only surface complexation for leaf mold. Based on the above results, we constructed a quantitative model incorporating surface complexation by leaf mold, sulfate reduction reaction by sulfate-reducing bacteria, Fe2+ dissolved reaction from leaf mold, and one-dimensional transport against the height of the column. The experimental results of pH and the concentration of each element were successfully represented by the quantitative model.

著者

加野 友紀 石戸 経士 中尾 信典

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.136, no.12, pp.140-150, 2020-12-31 (Released:2020-12-18)

参考文献数

45

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Heterogeneity in mudstone/shale layers has significant effects on seal layer integrity. The presence of intralayer sandstone channels in a seal layer may allow the buoyant CO2 to escape from the reservoir, even if the globally averaged permeability of the seal layer seems low enough. On the other hand, multi-layered structures are known to work often as baffles for the upward migration of CO2 in formations. In this paper, we investigate the storage capacity of multilayer formations with discontinuous seals. Numerical simulations are carried out to study the effects of seal layer discontinuity on the long-term behaviour of CO2 injected into deep saline aquifers. To represent a seal layer composed of low permeability rocks intersected by sandstone channels, ‘MINC' doubleporosity model is adopted. Also conducted is sensitivity analysis to investigate the effects of key parameters such as capillary pressure, relative permeability, temperature, and the thickness of the formations. The results show that CO2 injection into a sufficiently deep multi-layered reservoir enables CO2 to be stored and trapped in and around the reservoir without reaching to a shallow aquifer, even though seal layers have discontinuities. The upward movement of CO2 is greatly affected by capillary pressure of sandstone channels in seal layers. The relative permeability and the temperature-dependent CO2 properties have a significant effect on the final plume spread and the amount of CO2 dissolved or fixed by residual gas trapping.

著者

竹原 孝 及川 寧己 藤井 孝志 宮崎 晋行

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.136, no.11, pp.134-139, 2020-11-30 (Released:2020-11-28)

参考文献数

28

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A project of CO2 injection in the Ishikari coal basin (Yubari-shi, Hokkaido, Japan) since 2002 has shown that injection of CO2 into coal seams affected their permeability. Adsorption of CO2 caused swelling of the coal matrix and lowered the permeability of coal seams, probably because of closure of cleats and pores in the coal seams. However, a temporary recovery of permeability was observed after subsequent injection of N2, suggesting that some amount of adsorbed CO2 was replaced by N2 and the closure of cleats and pores were mitigated. However, the changes of mechanical properties of coal in the process are not yet fully understood. In this study, we injected CO2 and N2 into coal specimens recovered from the Ishikari coal basin and observed the changes of coal strength under hydrostatic pressure and temperatures typical of a coal basin. We conducted triaxial compressive strength tests on the coal specimens to clarify the effects of CO2 and N2 on the mechanical properties. Our results are summarized below.1) We verified that swelling and shrinkage of the coal were associated with adsorption and desorption, respectively, of CO2.2) The triaxial compressive strength tests showed that injection of CO2 caused decreases of peak strength and Young's modulus.3) Both coal strength and Young's modulus recovered when previously injected CO2 was replaced by N2.

著者

田中 敦子

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.136, no.11, pp.127-133, 2020-11-30 (Released:2020-11-28)

参考文献数

37

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In this review, the status quo of social acceptance of CCS is discussed in relation with international efforts to establish understanding on CCS. The author analyzed suspended 43 CCS project cases out of total 133 cases, and identified major impacting factors: economic reasons, legislative reasons, political reasons and social protests were 50%, 25%, 10% and 12% respectively. All of these impacting factors are within the range of social acceptance considerations, and could be solved by stakeholder engagement efforts. The author reviewed ISO/TC265 CCS standards which encourages to establish preferable social acceptance on CCS project by way of stakeholder engagement process and risk communication process. The author summarized recommendations from CCS stakeholder engagement process. Then, the author surveyed reports on public perceptions on CCS and CCS outreach works. Finally, the author researched literally succeeded and failed cases in of social acceptance gaining among communities in vicinity of CCS site and discussed the issue.

著者

近藤 めぐみ 小澤 教良 藤巻 宏太 五十嵐 敏文

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.136, no.10, pp.117-126, 2020-10-31 (Released:2020-10-29)

参考文献数

13

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The Une Mine excavates limestone by the bench cut method at Mt. Buko in the Chichibu area of Saitama Prefecture, Japan. Since the final rock slope, which is the largest scale in Japan, is beeing constructed at Mt. Buko, long-term monitoring and analysis have been carried out for the safety management of the rock slope. From the previous researches, a significant relationship between groundwater behavior and displacements of the rock slope was revealed, and suppressing the displacements of the rock slope, i. e., the reduction of the crack displacement rate, was accompanied by the lowering the groundwater level. Based on these results, countermeasures against the slope stability are being carried out in the mine. In this study, groundwater samples in the mine were collected and analyzed to characterize the groundwater chemistry, and to understand how the water quality was changed by rainfall and rock layers was examined. The results showed that the groundwater was classified into three depending on the layers, and that the groundwater in the alternated layer sensitively affected the rock slope.

著者

及川 寧己 竹原 孝 雷 興林 深沢 洋規 山口 勉

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.136, no.10, pp.110-116, 2020-10-31 (Released:2020-10-27)

参考文献数

17

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Elucidating the sealing capacity of caprock is very important because CO2 sequestered in deep aquifers can remain there for several hundred years in the CO2 sequestration. Threshold capillary pressure is a key property affecting sealing capacity, and therefore, the ability to measure the threshold pressure of a target rock conveniently is highly sought after. In this study, data collected during the CO2 injection process in triaxial compression tests of mudstone supposed to be a caprock were used to measure threshold pressure via the dynamic method. These triaxial tests were conducted to study the mechanical properties of mudstone below depths of 1000 m. The threshold pressure for 23 out of 26 test samples was successfully measured. Measured values ranged from 0.54 to 1.57 MPa, which was within a reasonable range compared to the results reported by three other studies that used similar mudstone specimens. A small amount of shrinkage induced by a pore pressure decrease, which was caused by a threshold pressure, was observed in the experiment. The threshold pressure showed a positive correlation with the shrinkage, implying that this pressure might be estimated from the shrinkage. Thus, a volumetric elastic constant was calculated from the shrinkage assuming that the decrease in mean pore pressure was half of the threshold pressure. The mean volumetric elastic constant was 0.92 GPa, which was about 40% lower than that of the rocks from which the test samples were obtained. These results indicate that the shrinkage value cannot be directly used to estimate the threshold pressure, and that a correction of this shrinkage value is necessary.