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Volume 58 (2004)
- Issue 6 Pages 547-
- Issue 5 Pages 448-
- Issue 4 Pages 337-
- Issue 3 Pages 242-
- Issue 2 Pages 142-
- Issue 1 Pages 3-
Volume 58, Issue 6
Displaying 1-8 of 8 articles from this issue
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Masahiro KAMEKURA2004 Volume 58 Issue 6 Pages 547-554
Published: 2004
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSThick and widespread evaporites are known from the Neo-Proterozoic to throughout the Phanerozoic. The contribution of the different salts to evaporite sequences varies greatly. This results from different modes of salt precipitation in shallow and deep basins, with and without brine reflux, often modified by sea-water seepage and loss of highly concentrated brine by leakage. Shallow groundwater/brine circulation and deeper, more closed flow systems largely transform the primary evaporites into secondary evaporites. Further modifications (tertiary evaporites) are caused by uplift and erosion of buried salt rocks.View full abstractDownload PDF (6639K) -
Eisaku MIYOSHI2004 Volume 58 Issue 6 Pages 555-562
Published: 2004
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSPoint defects in crystals consist of holes, interstitial atoms, and impurities. These point defects are important for physical and chemical properties of the crystals. In particular, impurities and electrons trapped in holes are responsible for optical properties of the crystals. In jewelry such as ruby and sapphire, d-d transition of impurity transition-metal atoms is the origin of its sparkling color. Similarly to the colors of ruby and sapphire, a crystal such as NaCl and MgO can be colored. The color of such crystals is due to electronic transitions of color centers, which consist of electrons trapped in hole sites. Interactions between photons and electrons in the color centers are explained from the basic theory of the quantum mechanics. The electronic structures of the F and U centers in NaCl and of various F centers in MgO are discussed from results obtained by recent molecular orbital calculations.View full abstractDownload PDF (6520K) -
Kenichi KAGIWADA2004 Volume 58 Issue 6 Pages 563-565
Published: 2004
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSDownload PDF (2018K) -
Hiroyuki TO2004 Volume 58 Issue 6 Pages 566-569
Published: 2004
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSDownload PDF (2849K) -
Reactive Crystallization of CaCO3 by Multistage Column CrystallizerHideki TSUGE, Kazuya TAMURA2004 Volume 58 Issue 6 Pages 570-578
Published: 2004
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSJapan is poor in natural resources, so it would be very beneficial if components dissolved in seawater can be used as resources. In our laboratory, reactive crystallization processes with components dissolved in seawater have been investigated by the absorption of CO2 gas that causes the greenhouse effect. In this study, Ca ion was selected as a component of seawater to produce calcium carbonate particles by means of the gas-liquid reactive crystallization. Additionally, a multistage column crystallizer was used, which is a column crystallizer partitioned with perforated plates. From an economical viewpoint, the multistage column crystallizer has been developed to overcome the redundancy of equipment due to the duplication of mixers and hardware in the cascade of MSMPR crystallizers. The aims of this study are to control the particle size of calcium carbonate and to evaluate the characteristics of the multistage column crystallizer. The staging effects of the multistage column crystallizer and the effects of operating parameters on the particle size and the conversion of Ca ion were experimentally investigated using the three-stage column crystallizer.
The following conclusions were obtained:
1. The particle size distribution of calcium carbonate obtained in the multistage column crystallizer becomes sharp compared to that obtained in the standard column crystallizer.
2. By increasing the initial concentration of calcium hydroxide, the particle size decreases and the particles are agglomerated easily.
3. From high-supersaturated solution, large particles can be obtained due to the strong effect of the agglomeration.View full abstractDownload PDF (6733K) -
Crystallization Characteristics of Lithium CarbonateHideki TSUGE, Ichiro KUZE, Kazuma FUJII2004 Volume 58 Issue 6 Pages 579-584
Published: 2004
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSDemand for lithium carbonate has been increasing as the material used in lithium ion batteries. In this research we studied the fundamental mechanism of reactive crystallization of lithium carbonate between a concentrated lithium solution obtained from seawater through an adsorption process and carbon dioxide contained in the flue gas of power plants and factories. The effects of operating factors, including the initial concentration of lithium hydroxide, reaction temperature and impeller speed, on the crystallization characteristics, such as nucleation rate and crystal growth rate, were investigated using an MSMPR(Mixed Suspension Mixed Product Removal)crystallizer. Nucleation rates increase with an increase in the initial concentration of lithium hydroxide and reaction temperature, and a decrease in the impeller speed. The crystal growth rate increases as the reaction temperature decreases and the impeller speed increases. The suspension density and the mean particle size increase with the same operating factors as the nucleation rate and the crystal growth rate, respectively.View full abstractDownload PDF (3666K) -
Hitoshi SHINDO, Daisuke ARAI, Daisuke SATO, Shinya YAMAZAKI2004 Volume 58 Issue 6 Pages 585-591
Published: 2004
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSNaCl whiskers grown from the surface of cellophane in contact with saturated aqueous solution on the other side were observed by means of optical microscopy and scanning electron microscopy (SEM). Square tube whiskers, often tapered at the top, were commonly observed.In situ observation revealed that the growth occurred at the base, not at the tip. Tapered whiskers were also formed starting at the tip. Characteristic structures were found with SEM at the bases of well-developed tube whiskers, namely, macro-steps growing horizontally around the outer surface, smooth bottom face presumably in contact with the cellophane surface, and a duct connecting the inside to the outside of the tube. The lowest part of the whisker was covered with water on the outside. The tube size changes depending on the balance between the growth rates in horizontal and perpendicular directions. Presence of rough parts at the inner surface suggests that the sidewalls were not necessarily in contact with water. Addition of [Fe(CN)6]4- with various concentrations markedly changed the whisker growth patterns by suppressing horizontal step motions on the (100) surface. At concentrations of 1-80μmol/L, whiskers started to grow as thin solid pillars. Horizontal connections were, then, gradually made at the base between the pillars, finally bunching into a common base. When two pillars having the same crystallographic orientation combined horizontally, a whole tube having a square cross section was generated. This explains how tube whiskers are formed. At a concentration of 0.5 mmol/L, tiny single crystals in the forms of tubes having rectangular cross sections, rectangular plates and blocks were formed. Among them, the tubes would have better chances of growing bigger in wet conditions in the absence of [Fe(CN)6]4-. At 1 mmol/L concentration, tiny sharp cones were formed.View full abstractDownload PDF (5471K) -
[in Japanese]2004 Volume 58 Issue 6 Pages 592-597
Published: 2004
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSDownload PDF (3820K)
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