Behavior of Impurities in Limestones during Calcination with Sodium Chloride

DOI Web Site 11 References
  • AITOH Shigeru
    Ueda Lime Manufacturing Co. Ltd.
  • UMETSU Yoshio
    Department of Applied Chemistry and Molecular Science, Faculty of Engineering
  • NARITA Eiichi
    Department of Applied Chemistry and Molecular Science, Faculty of Engineering

Bibliographic Information

Other Title
  • 塩焼き工程における石灰石中不純物の挙動
  • シオヤキ コウテイ ニ オケル セッカイセキチュウ フジュンブツ ノ キョドウ

Search this article

Abstract

A behavior of metal impurities in various limestones during the calcination with sodium chloride has been investigated to clarify the chemical effect of sodium chloride additive in the production of calcium oxide. The calcination of the limestones has been carried out at temperature range from 900 to 1200°C under air (oxidation) or carbon monoxide (reduction) atmosphere. Though a small amount of iron (III) oxide was changed to iron chloride under the oxidizing atmosphere, the removal of iron (II) oxide based on vaporization was not observed. However, under the reducing atmosphere, a large amount of iron (III) oxide was removed as FeCl2.<BR>When the mixture of the limestone (Fe2O3 : 0.12%) and sodium chloride with the molar ratio of Fe203 : NaCl=1 : 10 was calcined at 1100°C for 1 h, 41.0% of iron was removed. During the calcination process, sodium chloride was found to change partially Na2CO3 which being fusible as an eutectic mixture with excess sodium chloride. The other metal impurities in the limestone such as zinc, lead, copper, manganese, chromium were removed as chloride or metal state under the reducing atmosphere depending on each intrinsic m. p., b. p. and vapor pressure. On the other hand, alminium and silicon impurities were not removed and remained in the resulting calcium oxide as aluminosilicates. It was concluded that there are many factors affecting diversely the removal of impurities such as crystal grain size, crack, clay mineral content of the limestone as well as the reaction conditions such as calcination temperature and time, amount of sodium chloride additive and calcination atmosphere.

Journal

  • Inorganic Materials

    Inorganic Materials 4 (266), 13-19, 1997

    The Society of Inorganic Materials, Japan

References(11)*help

See more

Keywords

Details 詳細情報について

Report a problem

Back to top