Determination of Arsenic and Antimony in "Tatara" Steel Making Sample by Neutron Activation Analysis Combined with Multiple Gamma-ray Detection

Abstract

Synopsis : "Tatara" is a traditional iron and steel making process in Japan. It is a kind of directly refining steel making method using a sand iron. By the authors' study, it turned out that we could estimate the source region of raw material of "Tatara" by As and Sb concentration ratio in "Tatara" sample. However, the concentration of these elements in "Tatara" sample is very low (ppm or sub-ppm order), therefore, quantitative analysis is very difficult. In this study, As and Sb in "Tatara" sample (iron lump, sand iron and slag) were determined by Neutron Activation Analysis combined with Multiple Gamma-ray detection (NAAMG). NAAMG is high sensitive and non-destructive analysis method which combined Neutron Activation Analysis (NAA) and multiple gamma-ray detectors. Each "Tatara" sample (iron lump, sand iron and slag) was irradiated for 1-2 h (for As measurement), and 8-17 h (for Sb measurement) in JRR-3M HR irradiation field (thermal neutron flux was about 9.0ϫ10 17 n m Ϫ2 s Ϫ1). After the end of irradiation, cooling time was 4-5 d (As), and 19-36 d (Sb). Coincidence gamma-rays were measured by gamma-ray detector array, GEMINI-II for 1-8 h (As), and 2-41 h (Sb). Iron and steel certified reference materials were used as comparative standards. As a result of measurement, the concentration of As and Sb in all "Tatara" samples were determined by NAAMG and these were sub-ppm order. Lower Limit of Determination (LLD) of As was 0.1 ppm order and Sb was 0.01 ppm order.