A novel process for the recovery of platinum group metals (pgms) from ternary alloys using a hydrocarbonyl process is proposed. The hydrocarbonyl process involves treatment of a chloride solution of the pgms with carbon monoxide at ambient pressure. The results demonstrate that the process can provide high purity pgms from a ternary platinum-rhodium-palladium alloy such as that obtained from palladium-nickel catchment alloys used with platinum-rhodium gauzes during high temperature ammonia oxidation.

Since the 2018 review (1) one new light isotope of mass 165 (2) and four new heavy isotopes of masses 209 to 212 (3) have been identified for platinum (Table I). The heavy isotopes are only identified as being ‘particle stable’ – that is resistant to proton or neutron decay but all are expected to decay by beta decay in which an electron and anti-electron neutrino are emitted when a...

Platinum-rhodium gauzes are frequently used to catalyse the high temperature ammonia oxidation step for production of synthetic nitrogen-based fertilisers. The gauzes suffer from Pt loss in the form of platinum dioxide (PtO₂), due to the highly exothermic nature of the oxidation reaction. Industrially this is mitigated by installing one or more palladium-nickel catchment gauzes directly downstream of the combustion gauzes, to capture the lost Pt. The Pd-Ni catchment gauzes undergo severe structural modification during operation. In this study, we undertake a systematic study in a laboratory-scale furnace system to determine the role of each of the constituent gases O₂, H₂O and PtO₂ on the structural changes of the Pd-Ni gauzes. In addition, some samples are exposed to real industrial conditions in an ammonia combustion pilot plant reactor. Fresh and spent catchment gauzes are analysed by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA) and inductively coupled plasma mass spectroscopy/optical emission spectroscopy (ICP-MS/OES). By combining analysis of samples from furnace and pilot scale experiments, the main findings are that Pd-Ni gauzes undergo internal oxidation to nickel(II) oxide (NiO); which in the presence of steam results in Ni depletion and that PtO₂ vapour causes severe grain reconstruction. Furthermore, in laboratory-scale experiments no significant Pd loss is observed, which is in contrast to observations from the pilot plant where the samples are exposed to real post-ammonia oxidation conditions. Pd loss is likely attributed to some gas species contained in the real post-ammonia oxidation gas stream.

This paper provides a database of mechanical properties for most of the commercially available platinum alloys currently in use for jewellery purposes. The alloys were tested for mechanical properties through tensile and microhardness testing in the as-cast and hot isostatically pressed conditions. Microstructural characterisations were performed using scanning electron microscopy (SEM).