Process Development for the Recovery of PGMs from Catalytic Converters

摘要

The research was systematically conducted to develop of a recovery process for precious-metals from spent auto catalytic converters; a secondary source of PGMs. Batch experiments included leaching, solvent extraction, stripping, etc. Hydrochloric acid was used to leach out the metals from the catalytic converters at 30-50°C followed by solvent extraction earned out at room temperature using trioctyl amine (TOA) in toluene as extracting solution. At 50°C, 98% of Pt, 95% of Pd, and 99% of Rh were leached using 8 M HCl (acid/solid = 20 ml/g). For 2 wt% TOA, it was found that Pt and Pd were transferred into the organic phase leaving Rh in the aqueous solution. Nitric acid was the most effective stripping agent compared with hydrogen peroxide and hydrochloric acid. Direct recycling of organic phase for extraction after stripping significantly decreased the extraction efficiency. In order to maintain the extraction performance, a removal of acid in the organic phase was required. Finally, the overall precious-metal recovery process for catalytic converter and the analysis of process economics are presented.