STP861: Rapid Multielement Analysis of Gypsum and Gypsum Products by X-Ray Fluorescence Spectroscopy

    Kocman, V
    Research scientist, Domtar Research Centre, Senneville, Quebec

    Pages: 12    Published: Jan 1984


    Abstract

    A rapid and precise X-ray fluorescence method has been developed for the multielement analysis of gypsum and gypsum products. Gypsum specimens are calcined at 1000°C and then fused with sodium tetraborate flux into flat and transparent disks. The choice of a suitable flux system for the specimen preparation is critical because of a rapid decomposition of anhydrite, CaSO4, in lithium based fluxes at temperatures above 950°C. This decomposition causes not only visible imperfections in the disk surface but also alters considerably the concentrations of the major elements, calcium and sulfur. The procedure used for a fast setup of ten element analysis of gypsum on the Philips PW-1400 spectrometer utilizing synthetic standards and off-line calculated alpha coefficients is presented. Calibrations carried out with chemically analyzed specimens and their mixtures are compared to those performed with synthetic standards prepared by blending pure chemicals and anhydrite into the flux.

    Keywords:

    gypsum, X-ray fluorescence, thermogravimetry, analysis of gypsum, borates, Claisse fluxer, synthetic standards, matrix corrections


    Paper ID: STP30272S

    Committee/Subcommittee: C11.01

    DOI: 10.1520/STP30272S


    CrossRef ASTM International is a member of CrossRef.