Título

DETERMINATION OF TOTAL IRON CONTENT IN IRON ORE BY GLASS DISC FOR X-RAY FLUORESCENCE SPECTROMETRY WITH MATHEMATICAL MASS CORRECTION

DETERMINATION OF TOTAL IRON CONTENT IN IRON ORE BY GLASS DISC FOR X-RAY FLUORESCENCE SPECTROMETRY WITH MATHEMATICAL MASS CORRECTION

Autoria

Costa, Rodrigo Alves; Fazollo, Francisco; Silva, Rodrigo José da

DOI

10.5151/2594-357x-0007

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Resumo

The purpose of this study is to improve the precision and accuracy in the determination of total iron content in iron ore by fused glass disc for X-ray fluorescence (XRF), applying mass gain or loss mathematical correction during glass disc preparation. In addition, this study also aims at reducing economic costs of reagent and labor use by applying the new methodology as a routine in-house method for iron ore samples. In the new proposed method, all samples used for tracing the calibration curve and in testing are previously ignited in a muffle furnace at 1,000°C (1,832°F) for one hour. In this way, the samples read on the XRF spectrometer are in ignited base and are corrected by a mathematical factor as a function of mass loss on ignition (LOI). Certified reference materials (CRM) were used for assessing and comparing the method’s accuracy, with and without mathematical correction of mass. The method’s precision was assessed in samples with total Fe contents of 25% to 65%, in accordance with standard ISO 3085:2002 - Iron ores - Experimental methods for checking the precision of sampling, sample preparation and measurement. The results showed that using mathematical mass loss correction reduces the relative bias between the results for the reference materials (CRM) analyzed for total Fe by XRF from 1.12% to 0.10%, improving the method’s accuracy. In addition, a precision improvement from 3.05% to 0.32% was noted. Therefore, we conclude that the proposed method improves the results’ analytical quality and can be applied as an in-house method for iron ore samples, reducing the response time and testing costs, because the total iron content is, in general, determined by wet analysis.

 

The purpose of this study is to improve the precision and accuracy in the determination of total iron content in iron ore by fused glass disc for X-ray fluorescence (XRF), applying mass gain or loss mathematical correction during glass disc preparation. In addition, this study also aims at reducing economic costs of reagent and labor use by applying the new methodology as a routine in-house method for iron ore samples. In the new proposed method, all samples used for tracing the calibration curve and in testing are previously ignited in a muffle furnace at 1,000°C (1,832°F) for one hour. In this way, the samples read on the XRF spectrometer are in ignited base and are corrected by a mathematical factor as a function of mass loss on ignition (LOI). Certified reference materials (CRM) were used for assessing and comparing the method’s accuracy, with and without mathematical correction of mass. The method’s precision was assessed in samples with total Fe contents of 25% to 65%, in accordance with standard ISO 3085:2002 - Iron ores - Experimental methods for checking the precision of sampling, sample preparation and measurement. The results showed that using mathematical mass loss correction reduces the relative bias between the results for the reference materials (CRM) analyzed for total Fe by XRF from 1.12% to 0.10%, improving the method’s accuracy. In addition, a precision improvement from 3.05% to 0.32% was noted. Therefore, we conclude that the proposed method improves the results’ analytical quality and can be applied as an in-house method for iron ore samples, reducing the response time and testing costs, because the total iron content is, in general, determined by wet analysis.

Palavras-chave

X-ray fluorescence; Fused glass disc; Iron ore; Total Fe.

X-ray fluorescence; Fused glass disc; Iron ore; Total Fe.