Chrysotileの低温分解におけるCaCl_2添加効果と融体形成

概要

論文の詳細を見る
Mixtures of chrysotile (Mg_6Si_4O_<10>(OH)_8) and CaCO_3 were burned at temperatures ranging from 500℃ to 1000℃; the decomposition temperature of chrysotile was lowered by adding CaCl_2. Thermal analysis and succeeding SEM observation confirmed the formation of melts, which was supposed to be responsible for the effect of the added CaCl_2. The melts were detected even when the added CaCl_2 was as little as 1-5 mass% of the CaCO_3; the quantity of the CaCl_2 was smaller than that predicted from the phase diagram. Thermodynamic calculations of chemical equilibrium showed that forsterite (Mg_2SiO_4), which was a thermal decomposition product of chrysotile and had a fibrous shape, destructed at about 500℃. 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℃ is required. The present study has experimentally evidenced that the formation of melts enlarges the reaction interface between the chrysotile and the CaCO_3 so that the decomposition reaction can proceed even at lower temperatures.
社団法人日本セラミックス協会の論文
2006-10-01