Chrysotile の低温分解における CaCl2 添加効果と融体形成
Chrysotile の低温分解における CaCl2 添加効果と融体形成
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CaCl2添加和熔体形成对温石棉低温分解的影响
DOI：
10.2109/jcersj.114.844
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发表时间：
2006
影响因子：
1.1
通讯作者：
昭 小島
中科院分区：
文献类型：
--
作者：
昌生 藤重;良太 佐藤;礼乃 栗原;郁子 唐澤;昭 小島
在500℃~1000℃的温度范围内，对温石棉(Mg6Si4O10(OH)8)和CaCO3的混合物进行燃烧，加入CaCl2降低了温石棉的分解温度。热分析和随后的扫描电子显微镜观察证实了熔体的形成，这可能是添加CaCl2的影响的原因。当CaCl2的加入量只有CaCO3的1-5%时，仍能观察到熔体的存在，CaCl2的量比从相图预测的量要少。化学平衡热力学计算表明，纤蛇纹石的热分解产物镁橄榄石(Mg_2SiO_4)在500℃左右发生分解。在将石棉-水泥复合材料转化为Ca-Si系氧化物的常用分解方法中，分解反应通过固-固反应进行，反应速度较慢。因此，要提高反应速度，需要1000℃以上的反应温度。实验证明，熔体的形成扩大了温石棉与CaCO3之间的反应界面，使分解反应即使在较低温度下也能进行。
Mixtures of chrysotile (Mg6Si4O10(OH)8) and CaCO3 were burned at temperatures ranging from 500°C to 1000°C; the decomposition temperature of chrysotile was lowered by adding CaCl2. Thermal analysis and succeeding SEM observation confirmed the formation of melts, which was supposed to be responsible for the effect of the added CaCl2. The melts were detected even when the added CaCl2 was as little as 1-5 mass% of the CaCO3; the quantity of the CaCl2 was smaller than that predicted from the phase diagram. Thermodynamic calculations of chemical equilibrium showed that forsterite (Mg2SiO4), which was a thermal decomposition product of chrysotile and had a fibrous shape, destructed at about 500°C. In the common decomposition methods to convert asbestos-cement composites to oxides of Ca-Si system, the decomposition reaction occurs via a solid-solid reaction and reacts slowly. So to increase the reaction rate, a reaction temperature above 1000°C is required. The present study has experimentally evidenced that the formation of melts enlarges the reaction interface between the chrysotile and the CaCO3 so that the decomposition reaction can proceed even at lower temperatures.