A Review of Recovery of Palladium from the Spent Automobile Catalysts

The spent automobile catalysts (SAC) is the major secondary source of palladium and the production of SAC is increasing rapidly over years. The price of palladium keeps rising over the years, which demonstrates its preciousness and urgent industrial demand. Recovering palladium from the spent automobile catalysts benefits a lot from economic and environmental protection aspects. This review aims to provide some new considerations of recovering palladium from the spent automotive catalysts by summarizing and discussing both hydrometallurgical and pyrometallurgical methods. The processes of pretreatment, leaching/extraction, and separation/recovery of palladium from the spent catalysts are introduced, and related reaction mechanisms and process flows are given, especially detailed for hydrometallurgical methods. Hydrometallurgical methods such as chloride leaching with oxidants possess a high selectivity of palladium and low consumption of energy, and are cost-effective and flexible for different volume feeds compared with pyrometallurgical methods. The recovery ratios of palladium and other platinum-group metals should be the focus of competition since their prices have been rapidly increased over the years, and hence more efficient extractants with high selectivity of palladium even in the complexed leachate should be proposed in the future.

Metals smelting-collection method for recycling of platinum group metals from waste catalysts: A mini review

Platinum group metals (PGMs) are widely applied in the field of catalysts due to their excellent catalyst activity and high-temperature stability. The rapid generation of the waste catalyst has become the significant characteristic of PGMs with the accelerating consumption of limited PGMs nature resources. It is necessary to recover/recycle PGMs from a waste catalyst for both economic and environmental benefits. This paper reviews the PGMs recovery from waste catalysts using a metals smelting-collection process, which belongs to the main pyrometallurgical process, in the presence of various metal collectors, such as lead, copper, iron, matte, print circuit board (PCB) or reactive metals of calcium and magnesium. The current status of recovery of PGMs from waste catalysts through the addition of various metals as the collector is discussed and existing advantages and challenges are highlighted in this paper. Meanwhile, in the view of the promising processes of PGMs recovery, the influencing factors such as the economic, environmentally friendly, sustainable recycling, commercial scale, and low-grade materials are considered.