Reaction pathway led by silicate structure transformation on decomposition ofCaSiO3 in alkali fusion process using NaOH
(1. School of Materials and Metallurgy, University of Science and Technology Liaoning, Anshan 114051, China;
2. Key Laboratory of Chemical Metallurgy Engineering of Liaoning Province, Anshan 114051, China;
3. School of Materials and Metallurgy, Northeastern University, Shenyang 110004, China)
2. Key Laboratory of Chemical Metallurgy Engineering of Liaoning Province, Anshan 114051, China;
3. School of Materials and Metallurgy, Northeastern University, Shenyang 110004, China)
Abstract: The mechanism of decomposition of calcium inosilicate (CaSiO3) synthesized through chemical deposition method using analytical reagent NaSiO3？9H2O and CaCl2 during the alkali fusion process using NaOH was investigated by Raman spectroscopy in situ, X-ray diffraction and Fourier transform infrared spectrometer (FTIR). The results show that the tetrahedral silica chains within CaSiO3are gradually disrupted and transformed into nesosilicate with the isolated SiO4 tetrahedra at the beginning of the alkali fusion process. The three intermediates including Ca2SiO4, Na2CaSiO4 and Na2SiO3 appear simultaneously in the decomposition of CaSiO3, while the final products are Ca(OH)2 and Na4SiO4. It can be concluded that there exist two reaction pathways in the alkali fusion process of CaSiO3: one is ion exchange, the other is in the main form of the framework structure change of silicate. The reaction pathway is led bysilicate structure transformation in the alkali fusion process.
Key words: alkali fusion process; CaSiO3; intermediate; reaction pathway