Pattinson's Process, or pattinsonisation is a method for removing

silver Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...

from

lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...

discovered by Hugh Lee Pattinson in 1829 and patented in 1833. The process is dependent on the fact that lead which has least silver in it solidifies first on liquefaction, leaving the remaining liquid richer in silver. In practice several crystallisations were required, so Pattinson's equipment consisted basically of nothing more complex than a row of up to 13 iron pots, which were heated from below. Some lead, naturally containing a small percentage of silver, was loaded into the central pot and melted. This was then allowed to cool. As the lead solidified it was removed using large perforated iron ladles and moved to the next pot in one direction, and the remaining metal which was now richer in silver was then transferred to the next pot in the opposite direction. The process was repeated from one pot to the next, the lead accumulating in the pot at one end and metal enriched in silver in the pot at the other.Rowe, 1983. pp 189–190. Pattinson process Lead pot views.png, Sections of a pot Pattinson process Lead pots arrangement.png, Arrangement of pots used in a smelting mill The level of enrichment possible is limited by the lead-silver eutectic and typically the silver content of the silver-rich melt could not be raised above 2% (around 600 to 700 ounces per ton), so further separation is carried out by

cupellation Cupellation is a refining process in metallurgy where ores or alloyed metals are treated under very high temperatures and have controlled operations to separate noble metals, like gold and silver, from base metals, like lead, copper, zinc, arse ...

.Metallurgy - An Elementary Text Book, E.L.Rhead F.I.C F.C.S, Longmans, 1895, pp193-195 The process was economic for lead containing at least 250 grams of silver per ton.Tylecote, 1992. pp 157-158. Being the first process applicable to low-grade lead, it supplemented earlier

patio process The patio process is a process for extracting silver from ore. Smelting, or refining, was necessary because silver does not occur by itself in a natural state like some metals. Instead, it is made up of a larger ore body. Thus, smelting, or refin ...

and

pan amalgamation The pan amalgamation process is a method to extract silver from ore, using salt and copper(II) sulfate in addition to mercury. The process was widely used from 1609 through the 19th century; it is no longer used. The patio process had been used t ...

. It has been replaced by the

Parkes process The Parkes process is a pyrometallurgical industrial process for removing silver from lead during the production of bullion. It is an example of liquid–liquid extraction. The process takes advantage of two liquid-state properties of zinc. The fi ...

in the mid-19th century.

References

External links

Reference
to Pattinson's Process in mining.

Pattinson's process.
Pattinson's

white lead White lead is the basic lead carbonate 2PbCO3·Pb(OH)2. It is a complex salt, containing both carbonate and hydroxide ions. White lead occurs naturally as a mineral, in which context it is known as hydrocerussite, a hydrate of cerussite. It was ...

. Lead Silver Metallurgical processes {{industry-stub

See also

References

External links