著者

萩野 翼 富山 眞吾 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.137, no.2, pp.24-35, 2021-02-28 (Released:2021-02-26)

参考文献数

46

被引用文献数

2

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This study involved a mine in Akita Prefecture, Japan, which was closed in the 1970s and from which acid mine drainage (AMD) flows directly into a nearby river. Local residents use river water downstream of the mine, at a point-of-use, for agricultural purposes. In selecting factors to be used as a contribution index, the flow rate at multiple points including tributaries, and the concentrations of dissolved ions and heavy metals, were measured periodically and their trends evaluated. The river flow rate increases with rainfall, the AMD flow increases during the snowmelt season. These two periods and the river low-flow period were selected for study. Mine drainage is acidic (pH 3.0-3.6), and comprises Mg-SO4 type water quality throughout the year, with higher concentrations of SO42-, S-Fe, Cu, and Zn than those of river water. Downstream of the mine, where the AMD merges, the concentrations of heavy metals gradually decreased with increasing distance downstream, particularly during the low-flow period. The SO42- fluxes did not change from above to below the AMD merge-point, and the heavy metals fluxes decreased after merging in the order S-Fe > Cu > Zn. As for the factors that decrease the concentration and fluxes, the possibility is considered that S-Fe has an effect of oxidizing and precipitating Fe2+ due to the increase in pH by the mixing with river water and dissolved oxygen. And Cu, Zn has an effect of adsorption accompanying the formation of surface complex of iron precipitates. The AMD contains high concentrations (320-400 mg L-1) of SO42- due to the acidification of pyrite, and no precipitation of heavy metals was observed in the stream. Since precipitation phenomena such as heavy metals are not recognized in SO42-, an index indicating the degree of impact of AMD on the water quality of the point-of-use was calculated using SO42- as a contribution ratio; CR. The CR of the AMD to water quality at the point-of-use is in the range of 2%-12%.

著者

赤塚 真依子 玉村 修司 五十嵐 敏文 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.131, no.7, pp.459-464, 2015-07-01 (Released:2015-07-01)

参考文献数

30

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As one of the application of coal resources, domestic and overseas industries have been focusing on the recovery of methane from coal resources by methanogens using low-molecular weight acids or hydrogen that are converted from the organic matter in coal. For this application, it is essential to enhance the extraction of organic matter from low-rank coal (lignite) and maximize the conversion rate to consumable substrates for methanogen. In this study, we focused on the effects of chelating and reducing agents on the extraction of organics and metals from low-rank coal. Citric acid (chelating and reducing agent) and EDTA (chelating agent) were chosen as typical solvents. In the presence of citric acid, the Fe (II) concentration was correlated with the concentration of extracted organics as well as the total Fe. By contrast, the Fe (II) concentration was constantly at a low level for each EDTA concentration and pH. The absorbance (280 nm) of both solutions was almost the same when the total Fe concentrations were similar, regardless of the concentrations of Fe (II) , Al, Mg and Ca. These results indicated that organics from lignite were extracted with the leaching of Fe (III) and that the effects of reduction on the extraction of organics were insignificant. Excitation emission matrix spectra analysis suggested that humic acid was the main component of the extracted organics from lignite. The amount of acetic acid and formic acid released from 1g of lignite was calculated to be in the range 0.14 to 0.25 mg, and it was observed no correlation of the released amount with the citric acid /EDTA concentrations. Further research to obtain substrates such as low-molecularweight acids from the extracted organic materials is necessary for methane production using methanogens.

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

有馬 孝彦 佐々木 亮介 Carlito Baltazar TABELIN 田本 修一 山本 隆広 Tangviroon PAWIT 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.6, pp.64-76, 2020-06-30 (Released:2020-06-30)

参考文献数

21

被引用文献数

1

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Rocks generated from tunnel construction projects for roads and railways throughout Japan have often leached out hazardous trace elements, such as arsenic (As) and selenium (Se). In nature, the oxyanionic species of As and Se have a variety of chemical species, so speciation is one of the crucial factors in their migration through natural geologic media. In this study, column experiments consisting of four types of crushed rock samples containing As and Se, and a river sediment (RS) as an adsorbent obtained near the tunnel construction site were conducted to evaluate the leaching and adsorption behavior of arsenite (As (III) ), arsenate (As (V) ), selenite (Se (IV) ), and selenate (Se (VI) ). The results showed that the dominant speciation of As and Se in the effluent from the rock layer was As (V) and Se (VI), and that the addition of a bottom RS adsorption layer or the mixing of RS with the rock layer decreased the leaching concentrations of As (III), As (V), Se (IV), and Se (VI). Cumulative leachability (CL) for each speciation through the column experiments was calculated to evaluate the amounts of As and Se retained in RS. The calculated CL showed that the bottom RS layer or mixing of RS with the rock reduced the CL of As (III), As (V), Se (IV), and Se (IV) ranging from 60 to 89%, 73 to 89%, 9 to 75%, and 36 to 60%, respectively; however, mixing of RS with the rock layer was ineffective in decreasing CL of Se (VI). The reduction of CL may be due to adsorption and/or coprecipitation by iron and/or aluminum oxides contained in RS. These results indicated that utilization of RS for the bottom adsorption layer was effective in reducing As and Se concentrations irrespective of their speciation, although that of mixed with rock layer was effective only in reducing As concentrations irrespective of their speciation.

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

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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

吉田 哲也 五十嵐 敏文 朝倉 國臣 宮前 博子 彌富 信義 橋本 晃一

出版者

一般社団法人 資源・素材学会

雑誌

資源と素材 (ISSN:09161740)

巻号頁・発行日

vol.120, no.10,11, pp.577-583, 2004 (Released:2006-05-09)

参考文献数

22

被引用文献数

1 3

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To reduce the volume of precipitates generated by the neutralization of acid mine drainage (AMD) containing high concentrations of Fe and As, ferritization of the precipitates was attempted by a two-step neutralization process in which magnesium oxide (MgO) was used as the first neutralizer and sodium hydroxide (NaOH) as the second. Batch neutralization experiments with MgO and continuous flow experiments by the two-step neutralization were conducted in laboratories and an AMD treatment plant. The results showed that the precipitates by the neutralization were magnetized in the continuous flow experiments, although there was Al and Si that prevented the generation of ferrite in the AMD. This indicates that ferrite was formed from the precipitates after removing most of the soluble Al and Si by the first neutralization. In addition, aging of the precipitates under reducing conditions and returning the aged precipitates to a ferrite tank were required to form ferrite. The molar ratio of As to Fe in the precipitates reached a constant value at pH>3.5. This suggests the coprecipitation of As and Fe.

著者

吉田 哲也 五十嵐 敏文 朝倉 國臣 宮前 博子 彌富 信義 橋本 晃一

出版者

一般社団法人 資源・素材学会

雑誌

資源と素材 (ISSN:09161740)

巻号頁・発行日

vol.120, no.10,11, pp.577-583, 2004 (Released:2006-05-09)

参考文献数

22

被引用文献数

1 3

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To reduce the volume of precipitates generated by the neutralization of acid mine drainage (AMD) containing high concentrations of Fe and As, ferritization of the precipitates was attempted by a two-step neutralization process in which magnesium oxide (MgO) was used as the first neutralizer and sodium hydroxide (NaOH) as the second. Batch neutralization experiments with MgO and continuous flow experiments by the two-step neutralization were conducted in laboratories and an AMD treatment plant. The results showed that the precipitates by the neutralization were magnetized in the continuous flow experiments, although there was Al and Si that prevented the generation of ferrite in the AMD. This indicates that ferrite was formed from the precipitates after removing most of the soluble Al and Si by the first neutralization. In addition, aging of the precipitates under reducing conditions and returning the aged precipitates to a ferrite tank were required to form ferrite. The molar ratio of As to Fe in the precipitates reached a constant value at pH>3.5. This suggests the coprecipitation of As and Fe.