High temperature behaviour of platinum group metals in oxidizing atmospheres

Jehn, Hermann

doi:10.1016/0022-5088(84)90072-9

Cited by 109 publications

(63 citation statements)

References 23 publications

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“…The predominant volatile species are reported to be PtO 2 , IrO 3 and Ag 2 O. [21] The overall oxidation reaction is generally composed of the following partial steps: [17] (1) transport of O 2 molecules to the surface, (2) dissociation of O 2 and adsorption of O atoms, (3) formation and desorption (evaporation) of the volatile oxide and (4) transport of the oxide away from the surface. At higher pressures the oxidation rate is controlled by the last step, the diffusion of the volatile oxide through a gaseous boundary layer.…”

mentioning

confidence: 99%

Oxidation Damage of Spark Plug Electrodes

et al. 2005

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Knowledge about the erosion mechanisms of spark plug materials is of fundamental interest for the development of materials with a high resistance against electrode erosion. Endurance tests were performed to study the wear behaviour of platinum, iridium, silver and nickel as electrode materials for spark plugs between 200 and 900 °C. Oxidation must be the dominating mechanism, irrespective of the material. Additional calculations resulted in the suggestion of a plasma‐assisted oxidation process.

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confidence: 99%

Oxidation Damage of Spark Plug Electrodes

et al. 2005

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“…At higher temperatures (900°C to 1700°C), the vapour pressure of most PGM oxides become measurable and this may translate in Ru and Ir losses to the gas phase as oxide vapour during roasting (Jehn, H., 1984). Except for Pd, the vapour pressures of all PGM oxides are several orders of magnitude higher than their metallic states.…”

Section: Discussion Of Pgm Behaviour Over the 600°c To 1000°c Temperamentioning

confidence: 97%

Pyrometallurgical upgrading of PGM-rich leach residues from the Western Platinum base metals refinery through roasting

Bezuidenhout¹,

Eksteen

Akdogan

et al. 2013

Minerals Engineering

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The production of Platinum Group Metals (PGM) normally entails the smelting of PGM flotation concentrates, converting of the furnace matte and removal of the bulk of the Ni, Cu, Co, S and Fe t h r o u g h a t m o s p h e r i c a n d p r e s s u r e l e a c h i n g i n a b a s e m e t a l s r e f i n e r y t o p r o d u c e a P G M -r i c h concentrate. A number of impurities, mostly Se, Te, As, Bi, Os and Pb, are not removed significantly during the oxidising leach process in sulphuric acid media. In addition slag inclusions in matte leads to contamination of the PGM residues with silica, fayalite, magnetite and trevorite phases. Furthermore some Cu, Ni, Fe and S also remain. For this reason a typical Precious Metal Refinery (PMR) feed material contains less than 65% PGMs. The PMR is based on a chloride process and requires contaminants to be within narrow specification limits to prevent the formation of PGM residues that must be reprocessed or tolled, leading to poor first pass metal efficiencies and extending the duration of the production pipeline for efficient recovery.A process has been developed to significantly upgrade the BMR leach residues through pyrometallurgical processing, which include a multistep process of roasting under oxidising atmospheres, a two-step smelting process of the roasted calcine (with engineered slag chemistry and slag-refractory interactions) and subsequent atomisation of the molten alloy which can be fed as a slurry into the HCl/Cl 2 dissolution reactors in the precious metals refinery. These pyrometallurgical steps upgrade the BMR residue from a 45-50% grade up to an alloy grade of circa 90% PGMs, whilst removing the most deleterious elements with major process impacts on the PMR. This paper will focus primarily on the roasting step and it will investigate the thermochemical and mineralogical changes occurring during roasting. These changes were evaluated through a combination of thermochemical modelling and experimental investigation. The roasting step needs to be in an oxidative environment in order to achieve the vaporization of Se, Te, As, Os and S. The speciation of PGMs and their vaporization behaviour are presented, as well as the sensitivity of precious metals deportment to changes in roast conditions.

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“…Iridium is a face centered cubic metal with a high melting point (~2442EC), the highest shear modulus of any metal [1], the second-highest elevated-temperature strength among the refractory metals [2], good oxidation resistance [3], and the highest corrosion resistance of any element [4]. It is, therefore, attractive for high-temperature structural applications-especially in hostile environments.…”

Section: Introductionmentioning

confidence: 99%

Grain Growth Behavior, Tensile Impact Ductility, and Weldability of Cerium-Doped Iridium Alloys

McKamey¹

2002

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High temperature behaviour of platinum group metals in oxidizing atmospheres

Cited by 109 publications

References 23 publications

Oxidation Damage of Spark Plug Electrodes

Oxidation Damage of Spark Plug Electrodes

Pyrometallurgical upgrading of PGM-rich leach residues from the Western Platinum base metals refinery through roasting

Grain Growth Behavior, Tensile Impact Ductility, and Weldability of Cerium-Doped Iridium Alloys

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