COMBINED XRD-XRF METHOD OF Fe²⁺ DETERMINATION OF IN SINTERS

A method of combined X-ray diffraction-X-ray fluorescence determination of Fe²⁺ in medium-basicity agglomerates of ferruginous quartzite ores is proposed. The method is based on measuring the integrated intensity of the magnetite reflex (111) with allowance for the characteristic x-ray lines of the elements that interfere with direct determination of Fe²⁺ by x-ray diffraction as a part of the additive intensity correction model. An integrated system ARL 9900 Workstation combines x-ray spectrometer and x-ray diffractometer in a common analytical space. Factors affecting the results of Fe²⁺ determination in iron ore agglomerates — change in the absorption coefficient of the sample, formation of magnetite solid solutions, presence of Fe²⁺ in the wuestite composition, the amorphous phase, and also in the phases of iron sulfides are considered. The ways of taking them into account which suggest the use of the intensities of characteristic emission x-ray lines of Ti, Mg, Ca, Si and S, as well as the integrated intensities of (200) wustite and (104) hematite reflexes as correction channels are considered. A calibration curve plotted within the concentration range 11.1 – 15.0% illustrates the dependence of the intensity of (111) magnetite reflex on the content of Fe²⁺ expressed as oxide. The accuracy and repeatability of the results obtained by combined XRD-XRF method match the requirements of GOST R 53657–2009 standard. The use of the combined x-ray diffraction – x-ray fluorescence method in industrial practice provides significant shortening of the time of determination of the chemical composition of the medium-basicity agglomerates of ferruginous quartzite ores (470 sec for determination of the elemental composition and Fe²⁺, which includes 360 sec for registration of the diffraction data).

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