Reductive separation and slurry nebulization of converter matte for ICP-OES analysis of some platinum group metals and gold

Abstract

A new method that involves slurry nebulization–ICP-OES analysis and permits accurate estimation of platinum group metals (PGMs) and gold in converter matte has been developed. The method involves reduction of the PGMs and Au with SnCl₂ in concentrated HCl medium by heating on a laboratory hotplate and subsequent filtration of the hot mixture through a 0.45 µm membrane filter to separate the accompanying base metals. The resulting metallic precipitate of Au and PGMs was quantitatively transferred into a micronizing mill, ground for 30 min, diluted to 1000 ml with distilled-de-ionized water, and placed in an ultrasonic bath for 15 min to ensure homogeneity. An aliquot of this concentrated slurry was diluted to give a slurry of 0.005% m/v concentration prepared in 5.0% v/v hydrochloric acid and 1.0% m/v Triton X-100 as a dispersant and was directly nebulized into the ICP-OES for the determination of Au, Ir, Pd, Pt, Rh and Ru. The concentrations of Au and PGMs determined using ICP-OES were validated employing the standard additions method and by comparing with literature values that were obtained utilizing reductive separation and conventional dissolution procedure. The method, which allows separation of the PGMs and Au from a complex matrix offers the advantage of reduced analysis time (by ∼60%) and minimized contamination from additional sample preparation steps involved in the traditional procedure.