This dissolves all platinum-group metals, which are subsequently separated by solvent extraction. The individual metal solutions are then treated by conventional techniques to recover the various metals in a pure state. Consolidation Irrespective of the chemical separation processes used, the platinum metals are recovered in a finely divided metallic powder form. They can be converted to massive metal form by electron-beam melting. Assaying Assaying ores and concentrates for platinum-group metals is extremely difficult, since the concentration of any particular metal may be less than one part per million.
Initial concentration is achieved by fire assay.
The assay bead is dissolved in aqua regia and the metals separated and concentrated, often by solvent extraction. Dissolution of the bead is complicated by the presence of iridium, rhodium, or ruthenium, so that special solubilizing techniques may be required. The concentrated solutions are analyzed by atomic absorption spectroscopy or photometric techniques. Arc spectroscopy is sometimes employed directly on the bead obtained from fire assay. The mechanical properties of the six platinum metals differ greatly.