Separation and refining methods of palladium

Separation and refining methods of palladium: The main purpose of separation and refining is to remove impurities from the palladium leaching solution, enrich palladium (II) or palladium (IV), and then reduce it to sponge palladium after multiple refining.

1. Solvent extraction method: Solvent extraction includes organic phase extraction and two-phase aqueous extraction, which is generally carried out in the liquid phase at room temperature. The success of the solvent extraction process mainly depends on the selection of a suitable extractant. At present, a variety of reagents have been extensively studied, and acid chlorides are often used as the medium for extraction.
2. Precipitation method: Add an excess of precipitant to the leaching solution to form a poorly soluble compound of palladium, which is separated from trace and constant impurities. According to the type of precipitant used, it can be divided into inorganic precipitation method and organic precipitation method. The main precipitation methods are: sulfide precipitation method, thiourea precipitation method, xanthate precipitation method, dimethylglyoxime precipitation method, ammonium chloride precipitation method, etc.
3. Metal replacement method: Palladium dissolved in the solution is easily replaced by base metals, which plays the role of enrichment and preliminary purification to obtain crude palladium slag. Zinc, magnesium, aluminum, and iron are often used as replacement agents.
4. Ion exchange method: The ion exchange reaction is an ion exchange process caused by the chemical potential difference between the ion exchanger and the electrolyte solution.
5. Adsorption method: The key to the adsorption method is to select an adsorbent with special adsorption capacity. The main methods of adsorption from the solution are activated carbon adsorption and biomass adsorption.