ANALYSIS OF TANTALUM PRODUCTS BY INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY

Inductively coupled plasma atomic emission spectrometry was applied to the analysis of different products during the various steps of Ta pro cessing. The products were the ore tantalite, three solutions coming f rom the liquid-liquid extraction plant i.e. liquor, Ta-rich and Nb-ric h solutions, aluminothermic Ta (Ta containing about 15% m/m Al), pure Ta pentoxide (Ta2O5) and Ta metal. Dissolution was used for the solid materials without separation of the matrix. Dissolution of the tantali te ore sample was achieved by using a mixture of HBF4 + H2SO4 + HClO4 on a PTFE Vigreux-type column heated in an atmospheric pressure microw ave oven. Decomposition of the aluminothermic Ta, Ta2O5 and Ta metal w as achieved using a mixture of HF + HNO3 in a PTFE-lined pressure vess el. Because Ta and Nb are line-rich elements, a high-resolution sequen tial dispersive system was used as well as ;a careful selection of the wavelengths to avoid spectral interferences. Major, minor and trace e lements were determined in each matrix leading to a precision < 3% RSD . The recoveries for the analyte spiked samples were > 95%. Ta matrix were suitable to qualify Ta products for major applications, except fo r those for the microelectronics industry, which requires 5N or 6N gra de materials.