Daily analysis of ferroalloys by means of fluorescence X-ray

• Published in: Bunseki kagaku Vol. 20; no. 12; p. 1493
• Main Author: OKUDA, Kinnosuke
• Format: Journal Article
• Language: English
• Published: Tokyo Japan Science and Technology Agency 14.10.1971
• ISSN: 0525-1931
• DOI: 10.2116/bunsekikagaku.20.1493

Ferroalloys such as Fe-Mn, Si-Mn, Fe-Cr, Si-Cr and Ca-Si were daily analysed by means of fluorescence X-ray. Ferromanganese and ferrochromium slags were also examined. After sampling they were crushed into fine powder and pressed to each briquettes without binder. A full automatic analyser, Rigaku's IKF-III, was adopted. A motor-generator and a stabilizer were equipped to minimize supplied power fluctuation. It was seemed that they covered completely actual fluctuation of supplied powder. In the X-ray analyser, a LiF crystal was used for analysis of Fe, Mn, Cr and Ca, when a scintillation counter measured their X-ray intensity to compare with that of each standard samples. An EDDT crystal with a proportional counter was used to analyse Si and Al. An ADP crystal with the proportional counter was used for Mg. In all analysis Kα spectrum of each elements was selected. Analysis of Fe, Mn, and Cr in Fe-Mn, Si-Mn, Fe-Cr and Si-Cr were done under atmosphere, but in vacuo in other cases. To separate SiKα from FeKβ, an optimum base line and channel width were selected in a pulse height analyser conditions. Analysis of Si under 4% was done with a fixed time (80 sec.) method while a fixed count method was used in ether cases. All operating conditions were shown. Products of ferroalloys were usually specified according to their chemical composition, then calibration curves were classified in details within ranges of about 5% in the case of major elements and about 3% for minor Si. In the case of slags they were in the ranges of about 15%. Precision of calibration curves were statistically tested by t-distribution of 20 differences between X-ray values and wet chemical values for ferroalloys and 10 differences for slags. Standard deviation of repeatness of X-ray method in routine work during several years were shown in comparison with that of wet chemical method. In case of Si lower than 4% they were 0, 040.11%, being greater than that of wet chemical method. In other cases standard deviation of X-ray method were less than that of wet chemical method. Coefficients of variance in X-ray method were about 1% which seemed to be good results. No matrix effect was observed in this work.