How is silver recovered from zinc concentrates?

To recover silver from zinc concentrates, the material undergoes a multi-step metallurgical process:

• Roasting and Leaching: The zinc concentrates are roasted and leached with sulfuric acid to dissolve the zinc, leaving behind a residue containing lead, silver, gold, and some remaining zinc.1
• Slag Fuming: This residue is processed through slag fuming, where it is melted and treated with powdered coal or coke and air. This reduces the zinc to a metallic vapor, while the lead is converted to a metallic form that collects the silver and gold.1
• Lead Refining: The resulting lead bullion, which contains the silver and gold, is then sent to lead refining. During this stage, the Parkes process is typically used, where zinc is added to the molten lead to absorb the silver and gold into an alloy that can be skimmed off.123
• Final Recovery: The silver is ultimately isolated from the lead-gold-silver residue through cupellation and subsequent electrolytic refining methods, such as the Moebius or Thum Balbach systems.43