Trace amounts of platinum, otherwise lost, are recovered from the alum solution resulting from the digestion of spent alumina-based platinum catalyst in sulfuric acid. The alum solution is commingled with a normally liquid trialkyl phosphate and a platinum-containing residue forms at the interface of said liquids as they are allowed to settle out into an upper and lower liquid phase.
A process for sequentially and selectively separating gold and platinum group metals from aqueous solutions containing them is disclosed. First, ruthenium and osmium are oxidized to their tetroxides and then removed from the solution. Then, gold is removed by solvent extraction preferably with dibutyl carbitol. Next, palladium and platinum are removed by solvent extraction with an alkyl sulphide and tributyl phosphate respectively, care being taken to reduce iridium in solution before platinum extraction to prevent it extracting with the platinum. Then the iridium is reoxidized and removed from solution. Finally, rhodium is removed from the solution. Using this process gold, platinum and palladium of saleable purity can be extracted directly without the need for further refining steps.
A process for recovering a Group VIII noble metal with a high yield from an organic solvent solution containing a soluble complex of the noble metal and an organophosphorus compound comprising burning the organic solvent solution in a combustion zone, introducing the combustion product immediately into the aqueous absorbing solution to catch in the aqueous solution the particles of the noble metal and phosphorus oxide formed in the combustion, and recovering the noble metal particles from the aqueous solution.
The invention relates to the recovery of the constituent elements of catalysts containing precious metals, such as platinum and iridium deposited on aluminous supports. This recovery is accomplished by a substantially total solubilization of the catalysts by means of hydrochloric acid and by extraction, for example by means of ion exchange resins. This system allows for a good separation of the platinum and the iridium.
