Recycling methods for gold, silver, palladium, platinum and rhodium waste refining

In fact, in the research on secondary resource recovery of PGMs, almost all efforts are aimed at achieving higher cost-effectiveness, higher recovery rate and less environmental impact. With the research and development of recycling technology, the concept of environmental orientation has gradually formed. In order to achieve this goal, a comprehensive recycling method needs to be proposed:

(1) The leaching efficiency of precious metals is consistent with the stability constant and oxidation potential of their complexes. Improving the stability of precious metal complexes and reducing their oxidation potential are effective methods to increase the leaching rate. It is recommended to replace Cl2 with chloride salts to increase the concentration of negative CI and reduce the oxidation potential of precious metals.

(2) In order to improve leaching efficiency and reduce pollution, some auxiliary methods or pretreatments are crucial, such as supercritical fluid extraction and microwave-assisted leaching. Combining physical and chemical means such as heat and electricity, the concentration of platinum group metals in crude extracts is increased by methods such as hot pressing, and microbubbles are generated by fluid dynamic cavitation to increase the mass transfer between platinum group metals and electrodes to improve the current utilization rate and precious metal recovery rate of the electrodeposition process, thereby breaking the barriers of electrochemistry in the recycling of platinum group metals and other precious metals.

(3) Combining various pretreatment technologies with biological pretreatment processes can improve the recovery rate of platinum group metals and other precious metals.