Evaluation and improvement of the nickel sulphide fire assay method with ICP-MS finish, for analysis of rocks for the precious metals

The matrix effects of HCl, HNO;An improved method has been developed in which the reagent blank, matrix effect due to HCl, cost of chemicals and sample processing time have been reduced. (Abstract shortened by UMI.).;The effects of reducing the quantity of Ni and S used in the NiS fire assay method on the recovery of PGE and Au was investigated in a Pt ore grade sample and a low ppb level sample. In the Pt ore grade sample, the recovery of the precious metals was found not to depend on the mass of Ni used as collector. However, the recovery of Ru, Rh, Pd and Pt in the low ppb level sample was found to be a function of the collector mass used, while the recovery of Os, Ir and Au in the low ppb level sample was not. A model equation was derived from the mass balance equation of PGE between the sulphide and silicate liquids, and the bulk partitioning coefficient equation. From this equation, the partition coefficients (D) of the PGE were determined. The D values were functions of PGE concentrations.