Pyrometallurgical recovery technology of platinum group metals

PGMs pyrometallurgical recycling refers to the use of base metal collectors such as Cu, Pb, Ni, and Fe under the action of flux and reducing agent, and then pyrometallurgical smelting to make PGMs enter the base metal melt to form an alloy, and then the carrier and flux form slag and achieve directional enrichment of PGMs.

1. Lead capture: Lead capture is the most traditional precious metal enrichment process. Before 1980, foreign companies mainly used lead capture technology to batch process precious metal secondary resources. PbO, PGMs waste, reducing agent, and flux are mixed, and a protective agent is covered on the surface of the melt. After smelting at 1100~1300 ℃, the melt is poured out to obtain a Pb-PGMs alloy; Pb-PGMs alloy is blown at 900 ℃ to further enrich PGMs.
2. Copper capture: Some foreign precious metal recovery refineries use copper capture technology to recover PGMs, but the relevant technology is not disclosed. The research and application of copper capture technology in my country started late, and the relevant technology is relatively weak. Generally, CuO is used as a capture agent, and then a reducing agent is added to reduce CuO to Cu. After smelting at a temperature below 1500 °C, a Cu-PGMs alloy is obtained; the density of the slag and the alloy is different, and the slag and the metal are separated based on this, and the corresponding PGMs capture rate exceeds 95%.
3. Matte capture: Base metal sulfides and their mixtures can also be used as capture agents for PGMs, such as NiS, FeS2, pyrite, nickel matte, copper matte, etc. PGMs with sulfur affinity under high temperature conditions can be dissolved in the molten matte. The molten matte has metal-like properties, and PGMs atoms can bond with the molten matte (reducing the Gibbs free energy of the system), thereby achieving PGMs enrichment.
4. Iron capture: Fe is a green capture agent that can form a solid solution with PGMs. Fe-PGMs alloy can be obtained by mixing PGMs-containing waste, flux, Fe-containing collector and reducing agent and smelting them in a plasma furnace (1800~2000 ℃).