JSC URALINTEKH, (Yekaterinburg, Russia)

Е. А. Ryabukhin, Head of Refining Production, e.ryabukhin@pm-ural.com

LLC DTSM-GALVANI (Elektrougli, Russia)
А. Е. Sinyakov, Deputy General Director of Research and Development, Candidate of Chemical Sciences, sinyakovae@yandex.ru
М. S. Igumnov, External Advisor

Some properties of platinum-group metals are presented, and the behavior of iridium during platinum-group metal refining is considered, from feedstock dissolution through the production of individual iridium concentrates. Particular attention is given to the technological operations associated with the purification and separation of rhodium and iridium from other platinum-group metals by nitration of hydrochloric acid solutions and precipitation of sparingly soluble ammonium-sodium salts. The effects of process parameters, including nitration time, temperature (including autoclave treatment), acidity, and the content of non-noble impurities, on their transfer to ammonium-sodium salts upon the addition of ammonium chloride to the solution are demonstrated. The behavior of rhodium and iridium during nitration is compared. The mechanisms of nitro complex formation during the interaction of rhodium and iridium with sodium nitrite are described. The amount of platinum-group metals transferred to nitration hydroxides and methods for their recovery are evaluated. Recommendations are proposed for increasing the transfer of iridium to ammonium-sodium salts.

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