摘要
采用差热分析、X射线衍射、化学分析等检测分析手段,研究了白云鄂博铁精矿焙烧过程中气态氟化物的逸出机理。研究结果表明,白云鄂博铁精矿中的氟碳铈矿在499.5℃~558.6℃分解,饱和水蒸气气氛下焙烧时氟会逸出,其机理是水蒸气和氟碳铈矿中的氟生成HF;而萤石中的CaF_2与SiO_2、K_2O、Na_2O、Al_2O_3、MgO等脉石成分及焙烧气氛中的水蒸气自600℃开始反应,主要以SiF_4、KF、NaF、HF等气态氟化物形式逸出。在白云鄂博铁精矿焙烧过程中,焙烧温度及焙烧气氛中的水蒸气是影响氟逸出的重要因素。随着焙烧温度的升高,气态氟化物的逸出率明显提高;焙烧气氛中的水蒸气能够促进氟碳铈矿及萤石中的氟以HF形式逸出。本文探明了气态氟化物生成的机理及氟逸出主要影响因素,为改进白云鄂博铁精矿焙烧工艺、减少焙烧或烧结过程中氟的排放提供了理论依据。
The gaseous fluorides formation mechanism in the process of Bayan Obo iron concentrate roasted was studied by differential thermal analysis（ DTA）,X- ray diffraction（ XRD） and chemical analysis. The results show that bastnaesite（ CeCO3F） in Bayan Obo iron concentrate decomposes in the temperature range of 499. 5 ~ 558. 6℃; when it is roasted in wet air atmosphere,element flurine would be released as HF because the fluorine in the bastnaesite reacts with water vapor. In addition,fluorite（ CaF2） in Bayan Obo iron concentrate begins to react with gangue components SiO2,K2O,Na2O and water vapor in atmosphere from 600℃ to generate such gaseous fluorides as SiF4,KF,NaF and HF. During Bayan Obo iron concentrate roasting process,the temperature and content of water vapor in air atmosphere are very important factors that affect the emission rate of fluorine. The escaped gaseous fluorides significantly increases with the increase of roasting temperature,and the water vapor in roasting atmosphere can improve escaping of fluorine as HF gas from bastnaesite and fluorite. The formation mechanism of gaseous fluorides and main influencing factors of fluorine emission have been discussed,which provides a theoretical basis for improving its roasting technology to reduce emission of fluorine during the process of Bayan Obo iron concentrate roasting or sintering.
出处
《稀土》
EI
CAS
CSCD
北大核心
2014年第1期11-15,共5页
Chinese Rare Earths
基金
国家自然科学基金资助项目(51104088)
关键词
氟碳铈矿
萤石
焙烧
气态氟化物
逸出
bastnaesite
fluorite
roast
gaseous fluorides
escape
