Producer gas

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Revision as of 19:53, 2 December 2024 by Admin (talk | contribs) (Created page with "The '''Parkes process''' is a pyrometallurgical industrial process for removing silver and gold from lead. It is an example of liquid-liquid extraction. ==Principles== The process takes advantage of several properties of zinc. # Zinc has low melting (420°C) and boiling (907°C) points # As liquids, zinc and lead are immiscible # Noble metals are much more soluble in zinc than in lead. ==Overview== Zinc is added to liquid lead that contains silver, then th...")
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The Parkes process is a pyrometallurgical industrial process for removing silver and gold from lead. It is an example of liquid-liquid extraction.

Principles

The process takes advantage of several properties of zinc.

  1. Zinc has low melting (420°C) and boiling (907°C) points
  2. As liquids, zinc and lead are immiscible
  3. Noble metals are much more soluble in zinc than in lead.

Overview

Zinc is added to liquid lead that contains silver, then the silver preferentially migrates into the zinc. Because the zinc remains in a separate layer, it is easily removed. The zinc is then dry distilled leaving the silver and gold in the alembic and the condensed zinc in the retort. The process was patented by Alexander Parkes in 1850 and improved upon in 1851 and 1852. Alexander Parkes obtained three patents regarding this process.[1][2][3].

Process

  1. Melt the lead containing noble metals to be extracted
  2. Add elemental zinc
    Check: The zinc should rise to the surface and form a pool atop the lead
  3. Agitate or merely wait for long enough that the noble metals will migrate into the zinc pool
  4. Pour off the zinc-noble-metal fluid
  5. Distill the zinc out of the zinc-noble-metal fluid

See Also

  • Cupellation

References

  1. ↑ UK patent 13118, "Improvements in smelting and treating certain metals [...]", 1850
  2. ↑ UK patent 13675, "Separating silver from other metals", 1851
  3. ↑ UK patent 13997, "Separating silver from other metals", 1852
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