Determination of Ruthenium, Rhodium, Palladium, Iridium and Platinum in Copper-Nickel Sulfide Ores by Bismuth-Antimony Fire Assay / 分析化学

ABSTRACT

A bismuth-antimony fire assay method for the preconcentration of ruthenium, rhodium, palladium, iridium and platinum in copper-nickel sulfide ores was developed. 40. 0 g bismuth trioxide, 25. 0 g boric acid, 10. 0 g sodium carbonate and 1. 00 g starch were mixed with 10. 0 g sample in a 120 mL porcelain bowl, which was put in a furnace at 850 ℃. After 20 min the temperature was raised to 1000 ℃ and held for another 40 min, and then the bowl was taken out, with the slag poured, which left the bismuth button to air cooling. A two-step cupellation procedure was developed. During the first step, the bismuth button was cupellated in a magnesia cupel until its diameter reached 5 mm or so, then it was transferred to a crucible cover containing 20 g melting antimony and kept cupellating, at last a bead with a diameter of 1 mm was obtained. The bead was microwave-digested, after cooling down to room temperature, the solvent of which was transferred to a volumetric flask and diluted to 10 ml with water. Pt and Pd were analyzed by inductively coupled plasma-atomic emission spectrometry ( ICP-AES), while 99 Ru, 103 Rh, 191 Ir were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS), with 115 In, 185 Re as internal standard. RSD (n = 12) of the analysis results of five platinum group elements ( PGEs) in standard reference material GBW07196 ranged from 7. 04% to 9. 48% . Under the condition of 10 g sample, the detection limits (ng / g) for PGEs are 0. 027 for Ru, 0. 016 for Rh, 0. 11 for Pd, 0. 10 for Ir and 0. 11 for Pt. The method was applied to the determination of PGEs in GBW07194, GBW07195, GBW07196 with satisfactory results.