Amines solvent extraction, platinum

As already noted (p. 1073), the platinum metals are all isolated from concentrates obtained as anode slimes or converter matte. In the classical process, after ruthenium and osmium have been removed, excess oxidants are removed by boiling, iridium is precipitated as (NH4)2lrCl6 and rhodium as [Rh(NH3)5Cl]Cl2. In alternative solvent extraction processes (p. 1147) [IrClg] " is extracted in organic amines leaving rhodium in the aqueous phase to be precipitated, again, as [Rh(NH3)5Cl]Cl2. In all cases ignition in H2... 

The use of amine salts in the commercial solvent extraction of the platinum-group metals from chloride solutions is described in Section 63.3.2.5. 

Solvent extraction is proposed as a suitable method for PGMs (platinum group metals) recovery from low concentrated sources. Several extractants have been studied and proposed, e.g., hydroxyoximes, alkyl derivatives of 8-hydroxyquinoline, dialkyl sulphides, hydrophobic amines and quaternary ammonium salts, derivatives of pyridine and pyridinecarboxamides. However, the problems of a slow extraction rate or low metal separation remain to be solved. Looking for extractants permitting possibly fastest extraction of Pd, two phosphonium ionic liquids, i.e., [QP][C1] and [QP][Bis], have been used (Cieszynska et al., 2007 Cieszynska, 2010 Cieszynska Wisniewski, 2010, 2011). To overcome problems caused by the high viscosity of ILs, the mixtures with toluene have been used for extraction, similarly as for extraction of Zrf+. 

Phenolic (and amine) antioxidants in extracts of PVC have been titrated electrometrically with lithium aluminium hydride, using platinum or silver electrodes. Small amounts of water in the sample or analysis solvent have an influence on the results obtained by these procedures. 

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