Mechanism of tremolite carbonation |
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Authors: | Kyoung Won RyuMyung Gyu Lee Young Nam Jang |
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Affiliation: | a Korea Institute of Geoscience and Mineral Resources, Geological and Environmental Research Department, Daejeon 305-350, Republic of Korea b University of Science and Technology, 113 Gwahangno, Yuseong, Daejeon 305-333, Republic of Korea |
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Abstract: | The direct aqueous carbonation of fibrous tremolite was investigated by TEM, powder XRD, and FT-IR to elucidate the transformation mechanism of tremolite into calcite. The TEM study revealed that tremolite dissolves along the weak cleavage on (1 0 0) and (1 1 0) and the cleavage fragment fibers. The preferential release of Ca, relative to Si or Mg, into the solution resulted in the crystallization of compositionally homogeneous calcite and in the concurrent formation of proto-saponite. X-ray diffraction analysis revealed that the amount of product calcite increased rapidly within 15 min. Subsequently, after a 5 h carbonation period, it increased slowly to about 60%. The product calcite is euhedral. In contrast, the unreacted tremolite grains retain the original crystal structure even after prolonged carbonation. The morphological modification of tremolite from fibrous to round may have important implications for the elimination of its toxicity. |
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