巻号一覧
75 巻, 11 号
選択された号の論文の9件中1～9を表示しています
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特集「レアメタルのリサイクル技術」
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岡部 徹2011 年 75 巻 11 号 p. 601
発行日: 2011年
公開日: 2011/11/01
ジャーナル フリーPDF形式でダウンロード (149K) -
佐々木 秀顕, 前田 正史2011 年 75 巻 11 号 p. 602-606
発行日: 2011年
公開日: 2011/11/01
ジャーナル フリーThe hydrometallurgical recovery process of precious metals involves a great environmental load. This is because strong oxidant and complexing agents such as aqua regia are required to dissolve these metals which have high chemical stability. To enhance the dissolution, alloying with other metals may be effective as is conventionally used in production and refinement of some precious metals. When precious metal alloys are immersed in aqueous solution, the less noble metals in them dissolve preferentially and precious metals form transient particles. Thus, the Gibbs-Thomson effect, which explains the excess free energy of small particles, may contribute to the enhancement. Based on the assumption, an exposure to zinc vapor was proposed as a pretreatment for the leaching of precious metals. Precious metals form alloys or intermetallic compounds with zinc during the pretreatment, and if these products can be dissolved more easily than the pure metals, the environmental load involved in the recovery will be reduced. Dissolution rates of some precious metal-zinc compounds were evaluated quantitatively by channel flow double electrode method to discuss the effect of the pretreatment.
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松宮 正彦, 近藤 瞳, 倉知 明史, 綱島 克彦, 小玉 春2011 年 75 巻 11 号 p. 607-612
発行日: 2011年
公開日: 2011/11/01
ジャーナル フリーIt is very important to develop the recycle process for rare earth metals from the standpoint of environmental-friendly and saving-energy. We have already demonstrated that an economic recycle process of the rare earths from the waste of neodymium-based magnets. This study in rare earths recycle process was focused on the separation of the iron group metal and the recovery of the rare earths using a novel ionic liquid. In addition, this phosphonium-based ionic liquid was adaptable as an electrodeposition media for the recycle process because this kind of ionic liquid is unique physicochemical properties such as low viscosity and high electrochemical stability. The electrochemical and the diffusive properties of the iron complex were investigated from linear sweep voltammetry and chronoamperometry. The diffusion coefficient of Fe(II) was estimated to be the order of 10−11 m2 s−1 at 100°C. It was also revealed that the nucleation process of Fe(II) was proceeded on the instantaneous nucleation from Scharifker model. The overpotential of the nucleation process for Fe(II) was decreasing with elevating the bath temperature of the ionic liquid. Moreover, the selective separation of the iron metal was effectively possible for the electrodeposition at the constant potential. Furthermore, the electrodeposition in ionic liquid bath was allowed us to recover the neodymium metal at highly efficient.
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芝田 隼次, 村山 憲弘, 新苗 正和, 古山 隆2011 年 75 巻 11 号 p. 613-619
発行日: 2011年
公開日: 2011/11/01
ジャーナル フリーIn a present process to treat the tungsten carbide tool waste, the wastes are roasted in air and then an alkali leaching is carried out in an autoclave. However, the cost of reagent and energy consumed in this process are expensive. An environmentally friendly process is required to recover rare metals (Co and W) from the wastes. The effect of mechano-chemical (MC) treatment on leaching of rare metals was investigated in this study. The solvent extraction and crystallization-stripping methods were applied to separate and recover tungsten and cobalt in the leached solutions.
The MC treatment for the rare metal leaching is effective to dissolve rare metals from the wastes due to the change in crystalline structure of WC and oxidation of WC with KMnO4. Cobalt ions are extracted with D2EHPA by a cation exchange reaction. Tungsten in the leachate can be extracted by TOA(tri-octyl amine) as an extractant, because tungsten species exist as a form of anionic species in acidic solution. The rare metals in organic phase are recovered as insoluble salts such as oxalates and ammonium salts in the crystallization-stripping process.
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東 あるみ, 齋藤 範三, 荻 崇, 小西 康裕2011 年 75 巻 11 号 p. 620-625
発行日: 2011年
公開日: 2011/11/01
ジャーナル フリーMicrobial adsorption of soluble indium(III) was successfully achieved at room temperature over the pH range 2.3 to 3.5 using the gram-negative bacterium Shewanella algae. The microbial uptake of indium by the resting cells of S. algae was a fast process: 10-100 ppm indium(III) ions were completely collected into the bacterial cells within 30 min. The pH value and the cell concentration in aqueous indium(III) solutions had a significant effect on the adsorption fraction of soluble indium(III). The adsorption capacity of S. algae cells was determined as 41±2 mg-In/g-dry cells, indicating that the 100 ppm aqueous InCl3 solution was concentrated up to 680-fold by the microbial adsorption. The optimal pH for microbial adsorption was found to be 0.9-1.4 for Sn(IV), pH 2.3-3.5 for In(III), pH 2.9-4.3 for Al(III), respectively. For microbial recovery of indium from waste liquid crystal display (LCD) panel, moreover, S. algae cells were able to collect selectively indium(III) to the bacterial cells, after indium leaching from spent LCD panel with dilute HCl solution under hydrothermal conditions (120°C, 0.198 MPa, 5 min).
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中村 浩一郎2011 年 75 巻 11 号 p. 626-632
発行日: 2011年
公開日: 2011/11/01
ジャーナル フリーA simple technique for the detoxification of inorganic arsenic was successfully developed. It is believed that the proposed arsenic detoxification would be effective for rare-metal recovery. The objectives of the present study are as follows: (1) Development of the safe and efficient arsenic detoxification treatment technique, streamlining of processes, and cost reduction; (2) Establishment of a safe technique for recovering gallium from III-V compound semiconductors. The results are as follows. A bio-inspired catalyst system with vitamin B12 was developed for the detoxification reaction (turnover number for methyl transfer: >150). Inorganic arsenic was selectively removed from the acid solution of GaAs semiconductors by using a suitable adsorbent with cerium hydroxide. The removed inorganic arsenic was detoxified by using vitamin B12 and an amino acid. Without using the adsorbent with cerium hydroxide, the detoxified arsenic, arsenobetaine, was isolated from the mixture with gallium ion and arsenobetaine by column chromatography on silica gel after detoxification. As stated above, the proposed arsenic detoxification was used for the safe recovery of gallium from GaAs semiconductors, thus confirming that the technique was effective for the recovery of rare metals.
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論文
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德永 透子, 松浦 清隆, 大野 宗一2011 年 75 巻 11 号 p. 633-639
発行日: 2011年
公開日: 2011/11/01
ジャーナル フリーAlthough magnesium-based alloys have excellent mechanical properties, their very poor corrosion resistance limits their application. It has been considered that aluminum coating would solve this problem because aluminum has an excellent corrosion resistance. This study proposes a superior coating method based on the hot extrusion process. An aluminum plate set between the magnesium alloy billet and an extrusion die having an inversely angled face was successfully extruded together with the magnesium alloy billet and, as a result, the aluminum coated the extruded magnesium alloy with a uniform thickness. Corrosion tests based on dipping in HCl aqueous solution and potential measurement in NaCl aqueous solution showed that the extruded sample exhibited the same corrosion resistance as the aluminum. A three point bending test at room temperature resulted in fracture after plastic deformation, while at high temperatures between 100 and 300°C plastic deformation without fracture occurred. Notably, the intermetallic layer formed on the boundary between the magnesium alloy substrate and the aluminum coating layer plastically deformed without cracking at 300°C. A tensile test at room temperature resulted in a UTS of about 320 MPa and a plastic elongation of 18%.
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西元 学, 末岡 浩治, 本岡 輝昭2011 年 75 巻 11 号 p. 640-644
発行日: 2011年
公開日: 2011/11/01
ジャーナル フリーBy means of first principles calculation we studied the interfacial energy of void defects which were formed during the crystal cooling process in a Czochralski(CZ) puller. In this study the interfacial structure of void defect was assumed to be either a vacuum/oxide film/Si(111) structure or a vacuum/Si(111) structure. The calculation result showed that the interfacial energy was 0.886 Jm−2 in the case with an oxide film. It was close to the value(0.830 Jm−2) which was derived from the viewpoint of void defects formation around 1373 K. And it was 1.551 Jm−2 in the case without an oxide film, which was twice as large than an interface with an oxide film. For the range of Si crystal growth conditions for semiconductor use, we calculated the size and density of void defects with the interfacial energy which was obtained from first principles calculation in the case with an oxide film. The results agreed with the experimental results.
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越智 達朗, 久保田 学2011 年 75 巻 11 号 p. 645-650
発行日: 2011年
公開日: 2011/11/01
ジャーナル フリーThe elementary factors which determine the fatigue strength for finite life of the carburized steel were studied by investigating the properties of grain boundary and relationship between properties of grain boundary and fatigue strength for finite life. The precipitation of fine carbide in the prior austenite grain boundary was recognized. The fine carbide precipitated in the process of tempering. The fatigue strength for finite life was increased by disturbing precipitation of grain boundary carbide or refining grain boundary carbide. This was because crack propagation rate became slow by increasing grain boundary strength.
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