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Volume 78, Issue 7
Displaying 1-7 of 7 articles from this issue
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Special Issue on Recycle-Related Technologies of Rare Metals, and Their Frontier
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Katsuhiro Nose, Toru H. Okabe2014 Volume 78 Issue 7 Pages 241
Published: 2014
Released on J-STAGE: July 01, 2014
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Overview
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Ryo Kasuya, Takeshi Miki, Hisashi Morikawa, Yutaka Tai2014 Volume 78 Issue 7 Pages 242-249
Published: 2014
Released on J-STAGE: July 01, 2014
JOURNAL FREE ACCESSTo decrease the environmental load due to current Pt dissolution processes that use strong acids in combination with oxidizing agents, dissolution of Pt in hydrochloric acid (HCl) by way of alkali metal platinates was examined. Synthesis of Pt-containing double oxides was examined by calcining mixtures of Pt black and the alkali metal carbonates (Li, Na, K) at 600-800℃ in air. As a result, it was found that Li2PtO3 powder was obtained through the calcination of Pt black and Li2CO3 at 600℃. The formation of NaPt3O4 and Na2PtO3 was also confirmed upon the calcination of Pt black and Na2CO3 at 600-800℃, whereas a part of Pt remained unreacted in the calcined samples. In contrast, the calcination of Pt black and K2CO3 did not yield any Pt-containing oxides, even at 800℃. These results indicate that Li2CO3 has the highest reactivity among the examined alkali metal carbonates for the formation of the platinates. The time dependence of the concentrations of Pt and Li ions leached out of the resulted Li2PtO3 in HCl was monitored by inductively coupled plasma-optical emission spectrometry. The results showed that Li+ leached into HCl solution prior to Pt4+, and the solubility of the double oxides increased with decreasing calcination temperature. The dissolution behavior of Li2PtO3 was discussed based on its particle properties such as crystallite size, surface areas and anisotropy of the crystal.
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Kenichi Horai, Junji Shibata, Norihiro Murayama, Shigeki Koyanaka, Mas ...2014 Volume 78 Issue 7 Pages 250-257
Published: 2014
Released on J-STAGE: July 01, 2014
JOURNAL FREE ACCESSLithium ion battery (LIB) is composed of valuable metals such as Li, Co, Ni and Cu, and less valuable metals of Al and Fe. The toxic and flammable electrolyte, LiPF6, and organic solvents, propylene carbonate (PC), ethylene carbonate (EC) and dimethyl carbonate (DC) are used for an electrolytic solution. By this reason, the treatment process should have crushing, classifying and hydrometallurgical treatments after burning LIB at about 500℃.
The recycling technology of used LIB has been investigated in order to recover rare metals such as Li, Co and Ni with the combination process of crushing, classifying and hydrometallurgical treatments. The burnt LIB used for PC was employed in this research. Then, the physical treatments consisting of crushing, classifying and magnetic separation, and the chemical treatments containing acid leaching, hydroxide precipitation, solvent extraction and carbonate precipitation methods were applied. The operating conditions for several treatments were clarified.
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Hiroyuki Hoshi, Yu Miyamoto, Katsuyoshi Furusawa2014 Volume 78 Issue 7 Pages 258-266
Published: 2014
Released on J-STAGE: July 01, 2014
JOURNAL FREE ACCESSCarbothermal reduction technique was applied to extract rare earth elements from the machined powders of R-Fe-B based magnets, where R is Nd, Pr, Dy etc., generated as waste from the manufacturing process. After the oxidizing process to oxidize the powders and the reduction process to reduce iron oxide to iron metals by carbon, the powders were separated to the pig iron which mainly contained Fe and the slag which mainly contained rare earth elements. During the oxidizing process, the rare earth elements in the machined magnet powders needed to be oxidized, which could be achieved by heat-treatment at more than 1173 K for 1 hour under an air atmosphere. During the reduction process, the oxidized powders needed to be heat-treated at more than 1323 K under an argon atmosphere to separate them into the pig iron and slag. However, to separate these phases mechanically, the powders needed to be heat-treated at more than 1673 K, which is higher than the melting points of these two substances. And though the melting points of most of rare earth oxides are over 2173 K, the existence of B in the slag makes the melting point lower, which enables to separate to pig iron and slag at a temperature under 2173 K. Using this technique 93.6% of the rare earth elements were extracted from the machined magnet powders.
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Waki Nishijima, Katsunori Yamaguchi2014 Volume 78 Issue 7 Pages 267-273
Published: 2014
Released on J-STAGE: July 01, 2014
JOURNAL FREE ACCESSThe demand of platinum group metals (PGM) such as platinum, rhodium and palladium is recently increasing for a catalyst for decomposition of toxic gases in automobiles. The worldwide scarcity and high price of PGM accelerate the PGM recycling. The liquid copper has been used as a collector metal in one of the major methods for the recovery of PGMs from scraps of the automobile catalyst. With the aim of the minimization of the loss of PGM into slag phase, the distribution ratios of platinum, rhodium and palladium between the molten copper and the Al2O3-CaO-SiO2-Cu2O slag under MgO saturation with Q=0.36 and 0.52 (Q=(mass%CaO+mass%MgO)/(mass%CaO+mass%MgO+mass%SiO2)) were investigated at 1723 K in the range of the oxygen partial pressure 10−8 to 10−3 kPa. The copper solubility in the slag increases with increasing the oxygen potential, and liquid Cu2O separated from the Al2O3-CaO-SiO2-Cu2O slag with the oxygen partial pressure of 10−3 kPa. When the distribution ratio of PGMs between the slag and liquid copper was defined as LPGMs/Cu=(mass%PGM in slag)/[mass%PGM in Cu], LPGMs/Cu for platinum, rhodium and palladium were almost constant with increasing the oxygen potential up to 10−6-10−5 kPa and increased in the range of higher oxygen partial pressure. Based on these distribution ratios, activity coefficients of Pt and Pd oxides in the slag were thermodynamically calculated. The activity coefficients increase with increasing the oxygen potential.
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Regular Article
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Taichi Abe, Kiyoshi Hashimoto2014 Volume 78 Issue 7 Pages 274-279
Published: 2014
Released on J-STAGE: July 01, 2014
JOURNAL FREE ACCESSFor interstitial solid solutions various sublattice configurations have been applied in CALPHAD-type thermodynamic assessments. To construct a thermodynamic database for multi-component systems from the assessed binary and ternary systems, one difficulty is consistency of the thermodynamic models for the phases with sublattices. Previously, to combine parameters of the different sublattice configurations for the same phase, the thermodynamic assessment would need to be repeated. In the present work, we propose a simple method to convert parameters between the different sublattice configurations, and demonstrate that the present parameter conversions work well for the Ti-O binary system. Although it is a simple conversion process utilizing the known parameters, for the case where the valid composition range is limited, the thermodynamic database can be determined for multi-component systems. Furthermore, if a reassessment is required the obtained conversion can be used to estimate initial values for the parameter optimization.
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Tomo Ogura, Tomohiro Yagishita, Shinya Takata, Tomoyuki Fujimoto, Akio ...2014 Volume 78 Issue 7 Pages 280-285
Published: 2014
Released on J-STAGE: July 01, 2014
JOURNAL FREE ACCESSThe bondability of copper joints formed using a mixed paste of silver oxide (Ag2O) and copper oxide (CuO) that contained reducing solvents was evaluated in order to achieve bonds that exhibited high migration tolerance and could serve as Pb-free alternatives to the conventional bonds formed using high-melting point solders in electronics packaging. The Ag2O particles reduced into silver nanoparticles at 150℃, whereas the CuO reduced into copper nanoparticles about 300℃. The joints formed using the Ag2O/CuO mixed paste, when heated to the appropriate levels, exhibited bondability superior to that of conventional Pb-5Sn joints. The oxide film formed on the copper substrate was reduced by the combustion of polyethylene glycol 400, and bonding was achieved between the sintered layer and the copper substrate. A longer period resulted in the oxidisation of a few layers of sintered copper layers into Cu2O. The ion-migration tolerance of the Ag2O/CuO mixed paste was approximately four times that of a layer of pure sintered silver.
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