祁漫塔格成矿带磁铁矿Fe2+/Fe3+比值测定方法对比研究

EVALUATION OF THE METHODS FOR QUANTITATIVE DETERMINATION OF FE2+/FE3+ RATIOS OF MAGNETITE FROM QIMANTAG METALLOGENIC BELTS

为了厘清磁铁矿成分测试过程中Fe2+/Fe3+比值分析各种方法的准确性及适用范围;采用直接测氧法、Lβ/Lα强度比值法、电价差值法、剩余氧法和穆斯堡尔谱法,对祁漫塔格成矿带中典型矿床中磁铁矿的Fe2+/Fe3+比值进行了研究,结果表明电价差值法、剩余氧法和穆斯堡尔谱法是相对比较准确的测试方法,但穆斯堡尔谱法不是原位分析方法,存在适用范围的缺陷。

Through the determination of Fe2+/Fe3+ratios of magnetite from the Qimantag metallogenic belt,the quality of five different methods is evaluated.Oxygen as a super light element,affects the determination results of FeO and Fe2 O3 observably when direct oxygen measurement method is used.The valence state method,based on Lαand Lβspectral intensity ratio of Fe,is also unreliable for FeO and Fe2 O3 measurements,because it is hard to establish the relationship between Lβ/Lα(spectral intensity ratio)and Fe2+/Fe3+(content ratio).Relatively,the charge difference method,the surplus-oxygen method and Mssbauer spectroscopy are still the most favorable methods;however,Mssbauer spectroscopy is limited in spatial resolution to ca.200 mm,obliterating potential zonations in Fe2+/Fe3+ratio.