Dados do Trabalho

Título

COMPARING DIFFERENT PORTABLE X-RAY FLUORESCENCE UNITS AND CALIBRATION METHODS FOR GEOLOGICAL AND SOIL EXPLORATION

Resumo

Traditional methods of geological exploration are time-consuming and expensive. Portable X-ray fluorescence (pXRF) spectrometry is a fast and non-destructive method that allows for almost “real-time” data collection with minimal sample preparation and data processing. pXRFs are a well-known instrument used for material identification, geological exploration, and other fields. Usually, a pXRF unit has a set calibration already defined; the user chooses which method applies to the studied samples. For this study, two pXRF units, commonly used in the market, were used: brands A and B, calibrated with their own standard geological and geochemistry exploration methods. This study aims to assess the quality of the data and the effectiveness of these tools for “real-time” reliable data collection. To directly compare both pXRF instruments, 13 certified reference materials (CRM), including soils and Li ore pegmatites, were analyzed. The CRMs used were: OREAS 25a, 47, 147, 148, 750, 751, 752, 753, NIST 2709, 2710a, 2711, and SRM TILL 2 and 4. Both brands’ methods have three X-ray beams; each beam focuses on a specific energy range, prioritizing certain elements. For brand A, beam 1 ran for 40 s, beam 2 ran for 40 s, and beam 3 for 90 s. For brand B, beam 1 ran for 90 s, beam 2 ran for 40 s, and beam 3 for 40s. Linear regressions were created to assess the best recoveries per element between pXRF brands. The CRM recoveries were (brand A/brand B): Al (0.77/0.94), Si (0.81/0.81), P (0.78/0.87), K (0.32/0.46), Ca (0.99/0.99), Ti (0.96/0.99), Mn (1/0.96), Fe (0.99/0.99), Zn (1/1), Rb (1/0.99), Sr (0.99/0.99) and Ba (0.99/0.99). In general, light energy elements (Al, Si) had less satisfactory recovery when compared to heavy elements (Fe, Mn, Rb). Although recoveries varied per element, both instruments provided good results. In conclusion, both instruments are valuable tools for providing chemical data in a fast and precise way and complement each other when used together.

Palavras-chave

pXRF; geochemistry; environmentally friendly methods; sustainability; pedometrics.

Instituição financiadora

FAPEMIG, CNPq, CAPES, Lithium Americas Corporation, GSA, and MGPV.