著者

三村 均 柴田 雅博 秋葉 健一

出版者

東北大学

雑誌

東北大學選鑛製錬研究所彙報 (ISSN:0040876X)

巻号頁・発行日

vol.44, no.2, pp.182-190, 1989-03-25

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The chemical stability of pollucite (CsAlSi_2O_6) has been studied under hydrothermal conditions in relation to the leachability of cesium. At room temperature, the leachability of cesium from pollucite in the neutral pH region was very low. Under hydrothermal conditions (100 and 200℃) in sodium or potassium chloride solution, cesium leached out due to an ion exchange reaction forming new phases such as analcime (NaAlSi_2O_6) and leucite (KAlSi_2O_6) through an isomorphous substitution mechanism. In the presence of calcium or magnesium chloride, the pollucite phase recrystallised with the formation of anorthite (CaAl_2Si_2O_8) and clinochlore (Mg_5Al_2Si_3O_<10>(OH)_8) at the surface of the original pollucite and with the cesium leaching into solution. (Received November 7,1988)hydrothermal stabilitypolluciteleachabilitycesiumion exchangeanalcimeleuciteisomorphous substitutionrecrystallizationanorthiteclinochlore.

著者

三村 均 山岸 功 秋葉 健一

出版者

東北大学

雑誌

東北大學選鑛製錬研究所彙報 (ISSN:0040876X)

巻号頁・発行日

vol.44, no.1, pp.1-7, 1988-09-30

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The selective removal of Cs and Sr from high-activity-level water (HALW) has been studied by the use of various zeolites. The rate of adsorption of Cs and Sr increased with a decrease in size of zeolite particles, and the adsorption reached almost 100% after 5 h and 10 h of shaking for Cs and Sr, respectively. High distribution coefficients of Cs (K_<Cs>=10^4〜10^5) were obtained in the solution/zeolite ratio (V/m) region of about 300 to 1000. The presence of sodium ion fairly affected the distribution of Cs^+ and Sr^<2+>, and K_d values decreased with increasing concentration of Na^+. While the presence of boron almost had no effect on the distribution of Cs ; high K_<Cs> values (K_<Cs>≧10^5) were obtained below 5000 ppm of boron. Distribution coefficients of Cs and Sr were also independent of the equilibrium pH in neutral and alkaline regions at the ionic strength of 0.1. The removal of Cs and Sr from simulated HALW was effectively achieved by the use of mixed zeolites, and the K_d value was 7.0×10^3ml/g at the mixing ratio of 48/52 of X/chabazite.high-activity-level watercesiumstrontiumadsorption ratedistribution coefficientboronmixing ratiomixed zeolite

著者

張 世波 Acuna Cesar M. 矢沢 彬

出版者

東北大学

雑誌

東北大學選鑛製錬研究所彙報 (ISSN:0040876X)

巻号頁・発行日

vol.40, no.2, pp.143-154, 1985

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Three kinds of melting experiments were carried out for investigating the equilibria between ferrite slag and matte as follows : (I) Calcium ferrite slag and copper matte were brought into equilibrium under a current of SO_2-Ar gas. This corresponds to the condition of oxidizing smelting. (II) Calcium ferrite slag, copper matte and metallic copper were brought into equilibrium under a current of Ar gas. This corresponds to the condition of reducing smelting. (III) Three liquid phases of slag, matte and copper were brought into equilibrium under a current of SO_2-Ar gas. This corresponds to the direct production of copper by oxidizing smelting. In all of these cases, the distribution behaviour of arsenic, in addition to those of the principal components, was investigated. The solidified samples were investigated by microscope and electron probe microanalyzer (EPMA) to confirm the structure and composition for each phase obtained. The following crystallites were recognized in each phase. In the metal phase : a. Matrix of copper metal containing arsenic. b. Small bluish-grey particle of Cu_2S or bornite. c. Small greenish-grey crystallite of copper arsenide. d. Small light-grey arsenide consisting of Cu-Fe-As. In the matte phase : i. Bluish-grey matrix consiting of Cu_2S and bornite solid solutions. ii. Hair-like metallic copper. iii. Tiny dark grey crystallite of CaS. iv. Round dark grey particle consisting of calcium ferrite and bornite. v. White particle of iron. vi. Round yellowish-white grain consisting of copper and arsenic. vii. Tiny grey eutectic-type grains of Cu_2O recognized under very high oxygen potential. viii. Dark grey boundary crystallites observed in low grade matte. Sulfide-oxide mixture of Fe-Ca-S-O system. In the slag phase : 1. Large dark grey plate-like crystallites of 2CaO・Fe_2O_3. 2. Large grey plate-like crystallites of FeO・Fe_2O_3・CaO. 3. Massive light grey crystallites of FeO or Fe_3O_4. 4. Tiny dark grey grains observed in calcium ferrite crystallite. 5. Light yellow crystallites of FeS. 6. Brown or bluish-grey crystallites of bornite. 7. Greenish-grey plate-like or massive crystallites. Sulfide-oxide mixture of Fe-Ca-S-O system. 8. Small metallic copper grains. 9. White spherical crystallites of Fe occasionally containing As.

著者

菅野 卓治 橋本 裕之 大谷 登蔵

出版者

東北大学

雑誌

東北大學選鑛製錬研究所彙報 (ISSN:0040876X)

巻号頁・発行日

vol.34, no.1, pp.53-57, 1978-09-16

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The ion-exchange properties of cesium and strontium into zeolite from sodium salt solution has been studied in zeolite A, zeolite X, zeolite Y, mordenite and clinoptilolite. The distribution of cesium into mordenite from about 1〜2 M sodium chloride and sodium hydroxide solutions is considerably larger than that into zeolite A. The distribution coefficient for 2 M solution of sodium salts was about 300. Therefore, the seperation of cesium from sodium salt solution is possible by using mordenite. The distribution of strontium into zeolites from 1〜2 M solutions of sodium chloride and sodium nitrate were in the order of zeolite A>zeolite X>zeolite Y&sime;mordenite. The distribution coefficient of 230 was obtained for 1 M solutions of sodium salts. The anion in solutions had no effect on the distribution of cesium and strontium into zeolite from sodium salt solution.

著者

堀田 浩充

出版者

東北大学

雑誌

東北大學選鑛製錬研究所彙報 (ISSN:0040876X)

巻号頁・発行日

vol.33, no.1, pp.9-14, 1977-09-30

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The details of observations of the photoconductive spectra (0.7 to 2.5 μm) for the natural pyrite crystal are described with some supplements to the experimental results of the previous report. Several sub-peaks have been observed at 77 K near the principal peak of 0.9 eV which is attributed to the interband transition. The sign of dE_G/dT is determined to be negative from the temperature-variation of the peak. Photoconductive decay of the natural pyrite crystal has been observed at 77 K with the 2 μs pulsed white light. Three different life times (τ_j) have been derived from the empirical formula, V=Σ V_jexp (-t/τ_j), which applies to the observed decay curve. Their values of τ_j are about 80 μs, 5 ms and 65 ms, respectively.

著者

石川 遼平 井上 博文 三本木 貢治

出版者

東北大学

雑誌

東北大學選鑛製錬研究所彙報 (ISSN:0040876X)

巻号頁・発行日

vol.29, no.2, pp.193-200, 1974-03-28

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The relation berween cerium and oxygen in liquid iron together with the phase of deoxidation products at 1650℃ was studied. The following results were obtained : 1) The composition of deoxidation products is considered to be that the O/Ce ratio is 1.5 to 1.64 ([%Ce]<10 ppm), 2) If the deoxidation products are assumed as Ce_2O_3,the deoxidation equilibrium constant can be expressed as below, Ce_2O_3=2 Ce__-+3 O__- K=4.0×10^<-15>, 1650℃, [%Ce]<10 ppm.