含黑云母脉石铁精矿焙烧过程氟化物生成特性

Generation features of fluoride in fangue containing biotite during sintering

天然黑云母是白云鄂博铁精矿中含钾脉石的主要存在形式之一,焙烧过程会与其中的含氟脉石萤石形成氟化物,为了探明相关氟化物的逸出特性,针对天然黑云母、黑云母-CaF2、黑云母-CaF2-CaO体系,通过DTATG、XRD、SEM-EDS等分析方法研究了不同温度下,上述3种体系氟化物生成的热力学条件。结果表明,1 150℃下天然黑云母完全分解,转变为铁橄榄石（2FeO·SiO2）和白榴石（K2O·Al2O3·4SiO2）,1 250℃下只存在铁橄榄石一种矿物,其他成分均进入玻璃相中。黑云母-CaF2体系中的天然黑云母在1 180℃分解并完全消失,生成辉石（CaO·Al2O3·SiO2）,1 250℃时,中间产物辉石与CaF2结合生成枪晶石（3CaO·2SiO2·CaF2）,同时有SiF4逸出。黑云母-CaF2-CaO体系在950℃下生成枪晶石和钙铝黄长石（2CaO·Al2O3·SiO2）,直到温度升到1150℃,钙铝黄长石消失,枪晶石成为主要存在的矿物组成,1 250℃下有SiF4逸出。

Nature biotite is the main state of gangue contain potassium element in Bayanobo iron ore concentrate,which can act with fluorite and generate fluoride.In order to reveal the generation features,the thermodynamic conditions of formation of fluoride about biotite,biotite-CaF2 and biotite-CaF2-CaO system were studied by means of DTA-TG,XRD,SEM-EDS analysis method.The results show that nature biotite is decomposed completely into fayalite（2 FeO·SiO2）and leucite（K2 O·Al2O3·4 SiO2）at 1 150℃.The other components enter into glass phase,while only fayalite exists at 1 250℃.The natural biotite in the biotite-CaF2 system decomposes and completely transforms into pyroxene（CaO·Al2O3·SiO2）at 1 180 ℃.Subsequently the intermediate pyroxene combines with CaF2 and form cusipidine（3 CaO·2 SiO2·CaF2）,while SiF4 escapes at 1 250℃.Meanwhile the biotite-CaF2-CaO system produces cusipidine and gehlenite（2 CaO·Al2O3·SiO2）at 950℃,which disappears until the roasting temperature rises to 1 150℃.Then cusipidine becomes the main mineral composition while SiF4 escapes at 1 250℃.