Bulletin of the Society of Sea Water Science, Japan
Online ISSN : 2185-9213
Print ISSN : 0369-4550
ISSN-L : 0369-4550
Volume 27, Issue 5
Displaying 1-6 of 6 articles from this issue
  • Determination of Trace Inorganic Elements in Common, Industrial Salts and Salt Dome by means of Atomic Absorption Spectrometry (I)
    Soichiro MUSHA
    1974 Volume 27 Issue 5 Pages 255-262
    Published: 1974
    Released on J-STAGE: February 19, 2013
    JOURNAL FREE ACCESS
    When a quantitative analysis on the trace of microgram arsenic contained in salt was conducted by atomic absorption spectrophotometry, the arsenic was reduced to arsine as the result of employment of zinc and hydrochloric acid.
    This arsine was trapped in solid form in a U-tube filled with glass beads which had been frozen with liquid nitrogen around-150°, and then evaporated from the U-tube to the room temperature. The gaseous arsine was swept out with nitrogen into a premixed argon-hydrogen flame for absorption measurement. The atomic absorption for the arsenic was measured at the 193.7nm resonance radiated from an electrodeless discharge lamp.
    This atomic absorption method indicated that although most of the elements gave no interference with the production of arsine, tellurite and nitrate ions interfered with the reduction of arsenic to arsine.
    In case 2 gram salt was used as sample, the most suitable optimum sample weight for arsenic was between 0.05 and 0.4μg. In this range of arsenic, the variation coefficient of the measurement of atomic arsenic was found to be about 7%, and the sensitivity for 1% absorption for arsenic was 6×10-9g.
    When the amount of arsenic contained in salt was determined by the above method, the salt produced by old-fashioned making method was found to contain nearly the same amount of arsenic as natural sea-water, but the one produced and extremely refined by the modern making method was found to contain so little that no arsenic could be detected. This pointed out an environmental problem that the human-kind would have to eat salt containing no arsenic in the future.
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  • Studies on the Scale Prevention in Concentrating Process of Sea Water (Part 4)
    Shizuo SUGITA, Tetsuzo ISHIKAWA, Mitsuo ONO, Kiyomi SOGA, Misae KOHASH ...
    1974 Volume 27 Issue 5 Pages 263-271
    Published: 1974
    Released on J-STAGE: February 19, 2013
    JOURNAL FREE ACCESS
    In this paper, the behaviors of components of scales in the brine, and the composition and crystal form of adhered scales and seed crystals, were studied following the previous paper.
    1) When “additive treatment” was applied, a considerable decrease in the heat transfer coefficient was observed. This was attributed to deposition of the scale of paste form.
    2) When the new method, in which equivalent amounts of CaCO3 and Mg (OH) 2 were added together with slaked lime, was applied, the formation of CaCO3 and Mg (OH) 2 crystals were observed.
    3) The relationship between the temperature of brine and the constituents of adhered scale was recognized. And the correlation of the effect of scale prevention among “additive treatment”,“addition of alkaline reagent”,“addition of seed” and the “new method” was made clear.
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  • Studies on the Corrosion of Metals in a Salt-Making Apparatus and Its Protection (XII)
    Yukio NAGAOKA, Shiro AIDA
    1974 Volume 27 Issue 5 Pages 272-284
    Published: 1974
    Released on J-STAGE: February 19, 2013
    JOURNAL FREE ACCESS
    A corrosion test on heating tubes made of various types of stainless steel was conducted by using a model heat exchanger in two actual salt-making plants. The results obtained were as follows:
    1. In a 7, 100 hour test conducted in a refined-salt making plant, no stress corrosion cracking was observed to take place on AISI type 304, 316, and 316L heating tubes. However, some pitting corrosion and deposit attacks were found to occur at the inlet or outlet of those heating tubes other than type 316L.
    2. In a 5,700 hour test conducted in a common-salt making plant, stress corrosion cracking was observed to occur on types 304, 304L, and 316L with the exception of type 329. These cracks were found to take place near the welded parts on the outlet side of type 304 and 304L, respectively. Also, some cracks were seen on the outside of the tube plate. The cracking on the outside of the tube plate seemed to be caused by the tensil residual stress due to plastic deformation. In the middle part of each tube was also observed some pitting corrosion similar to deposit attack. The test showed that there took place more corrosion on the heating tubes in the common-salt making plant than in the refined-salt making plant. This was considered to be due to the fact that the concentration of MgCl2 in the salt used in the common-salt making plant was greater than the one used in the refined-salt making plant.
    3. As the result of the two tests, type 329 proved to be the most suitable stainless steel for a heating tube in a common-salt making plant. This steel seemed to be a most promising one especially for a crystalizer used in high-temperature zones in a common-salt making plant. Types 316 and 316L were considered usable for a crystalizer in a refined-salt making plant, and also for a crystalizer in low-temperature zones or for a concentraing evaporator in a common-salt making plant. Types 304 and 304L were not suitable.
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  • Studies on the Corrosion of Metals in a Stalt-Making Apparatus and Its Protection (XIII)
    Yukio NAGAOKA, Hiroshi IZUURA, Kenichi KAGIWADA
    1974 Volume 27 Issue 5 Pages 285-294
    Published: 1974
    Released on J-STAGE: February 19, 2013
    JOURNAL FREE ACCESS
    Experiments were carried out to establish the technique of cathodic protection with impressed current for the heat exchanger of the salt-making evaporator consisted of different metals. The results obtained were as follows:
    1. The protection potential of copper, naval brass, and stainless steel in mother liquid at 30°C under static condition was assumed to exist near -500mV, -650mV, and -800mV (SCE), respectively.
    2. A corrosion protection test was conducted by using a model evaporator (outside heating type) with a stainless steel water box, naval brass tube plate, and a copper heating tube in mother liquid containing 15 volume % salt crystals at 112°C under dynamic condition of the flow rate of 2m/sec. for 120 hours. This test showed that the water box, the tube plate and the end of the heating tube were perfectly protected from corrosion at a cathodic potential of -800mV (current density 0.8A/m2).
    3. From the potential distribution over the internal surface of the tube in a basic test and from the distribution of corrosion rate in a corrosion protection test, the protection of the heating tube seemed to be limited to the length of 100mm from the tube plate. The distribution of corrosion rate was found to correspond to the deposit by electrolysis.
    4. Most of the Mg (OH) 2 and CaCO3 deposits were observed at the end of the tube, but the speed of scale deposition was under the critical value (0.03g/m2hr). 5. The concentration of free Cl2 by electrolysis was 0.1ppm at 2.2-3.0 Volt of bath voltage, and there seemed to be no corrosion problem for this apparatus.
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  • Shoji KIMURA
    1974 Volume 27 Issue 5 Pages 295-299
    Published: 1974
    Released on J-STAGE: February 19, 2013
    JOURNAL FREE ACCESS
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  • [in Japanese]
    1974 Volume 27 Issue 5 Pages 300-304
    Published: 1974
    Released on J-STAGE: February 19, 2013
    JOURNAL FREE ACCESS
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