Characterization of Mineralogical Changes of Chrysotile and its Thermal Decomposition by Heat Treatment

열처리에 따른 백석면의 광물학적 특성 변화와 열분해 과정 연구

  • Jeong, Hyeonyi (Department of Geological and Environmental Sciences, Chonnam National University) ;
  • Moon, Wonjin (Korea Basic Science Institute, Gwangju Center) ;
  • Roh, Yul (Department of Geological and Environmental Sciences, Chonnam National University)
  • 정현이 (전남대학교 지질환경과학과) ;
  • 문원진 (한국기초과학지원연구원 광주센터) ;
  • 노열 (전남대학교 지질환경과학과)
  • Received : 2015.12.24
  • Accepted : 2016.03.28
  • Published : 2016.04.28


Chrysotile is a 1:1 sheet silicate mineral belonging to serpentine group. It has been highlighted studies because of uses, shapes and structural characteristics of the fibrous chrysotile. However, it was designated as Class 1 carcinogen, so high attentions were being placed on detoxification studies of chrysotile. The objectives of this study were to investigate changes of mineralogical characteristics of chrysotile and to suggest detoxification mechanism of chrysotile by thermal decomposition. Samples for this study were obtained from LAB Chrysotile mine in Canada. The samples were heated in air in the range of 600 to $1,300^{\circ}C$. Changes of mineralogical characteristics such as crystal structure, shape, and chemical composition of the chrysotile fibers were examined by TG-DTA, XRD, FT-IR, TEM-EDS and SEM-EDS analyses. As a result of thermal decomposition, the fibrous chrysotile having hollow tube structure was dehydroxylated at $600-650^{\circ}C$ and transformed to disordered chrysotile by removal of OH at the octahedral sheet (MgOH) (Dehydroxylation 1). Upon increasing temperature, it was transformed to forsterite ($Mg_2SiO_4$) at $820^{\circ}C$ by rearrangement of Mg, Si and O (Dehydroxylation 2). In addition, crystal structure of forsterite had begun to transform at $800^{\circ}C$, and gradually grown 3-dimensionally to enstatite ($MgSiO_3$) by recrystallization after the heating above $1,100^{\circ}C$. And then finally transformed to spherical minerals. This study showed chrysotile structure was collapsed about $600-700^{\circ}C$ by dehydroxylation. And then the fibrous chrysotile was transformed to forsterite and enstatite, as non-hazardous minerals. Therefore, this study indicates heat treatment can be used to detoxification of chrysotile.


Supported by : 한국환경산업기술원


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