EARTH

[3812-23-01] Study on mechanism of fayalite formation by solid state reaction in sintering process

○Zhongbing Wang¹, lifeng Zhang¹, Zongwen Zhao¹, Jie Lei¹, Yanjie Liang^1,2, Hui Liu^1,2, Liyuan Chai^1,2, Yanchun Li^1,2 (1. Central South University, 2. Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution)

Chairman: Jae-Young Jung （Kyungpook National University）, Liyuan Chai (Central South University)

Keywords:fayalite (Fe2SiO4), chemical diffusion, heterogeneous occupancy, formation mechanism

Fayalite is the main deposit phase of iron in copper slag , which is often found in the reducing environments . But the oxidation state of the terrestrial mantle restricts the amount of Fe found in olivine on Earth . For this reason , synthetic fayalite is needed for man made controlling a reducing atmosphere . Here we present a method for the synthesis of fayalite by solid state reaction under a normal pressure and lower temperature conditions . The progress of fayalite formation was monitored by XRD and XPS analyses at different time intervals . Powder X-ray diffraction analyses indicate that the produced fayalite is nearly pure, with minor amounts of silica in the batches. The Si2p and O1s peaks binding energies, intensity and line-shape were analyzed extensively to show the diffusion ofcation and the growth of crystal at different stages of heat treatment. Analysis of the Fe 2p_3/2 line-shape supported the formation of new keys Fe-O-Si during fayalite synthesis. SEM images of fayalite crystals show that the size range in between 100 and 800nm. Regulation of the redox environment was the critical challenge for this synthesis, but careful control of oxygen fugacity during sintering ensured fayalite crystallization.