The Betts electrolytic process is an industrial process for purification of
lead
Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...
from
bullion
Bullion is non-ferrous metal that has been refined to a high standard of elemental purity. The term is ordinarily applied to bulk metal used in the production of coins and especially to precious metals such as gold and silver. It comes from ...
. Lead obtained from its ores is impure because lead is a good solvent for many metals. Often these impurities are tolerated, but the Betts electrolytic process is used when high purity lead is required, especially for
bismuth
Bismuth is a chemical element; it has symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs nat ...
-free lead.
Process description for lead
The
electrolyte
An electrolyte is a substance that conducts electricity through the movement of ions, but not through the movement of electrons. This includes most soluble Salt (chemistry), salts, acids, and Base (chemistry), bases, dissolved in a polar solven ...
for this process is a mixture of lead fluorosilicate ("PbSiF
6") and
hexafluorosilicic acid (H
2SiF
6) operating at 45 °C (113 °F). Cathodes are thin sheets of pure lead and anodes are cast from the impure lead to be purified. A potential of 0.5 volts is applied. At the anode, lead dissolves, as do metal impurities that are less noble than lead. Impurities that are more noble than lead, such as silver, gold, and bismuth, flake from the anode as it dissolves and settle to the bottom of the vessel as "anode mud." Pure metallic lead plates onto the cathode, with the less noble metals remaining in solution. Because of its high cost, electrolysis is used only when very pure lead is needed. Otherwise pyrometallurgical methods are preferred, such as 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 ...
followed by the
Betterton-Kroll process.
[Samans, Carl H. ''Engineering Metals and their Alloys'', 1949 MacMillan]
History
The process is named for its inventor Anson Gardner Betts who filed several patents for this method starting in 1901.
See also
*
Processing lead from ore
*
Lead smelter
*
Electrochemical engineering
Electrochemical engineering is the branch of chemical engineering dealing with the technological applications of electrochemical phenomena, such as electrosynthesis of chemicals, electrowinning and refining of metals, flow batteries and fuel c ...
References
External links
Bismuth----
Bismuth
Lead
Electrolysis
Metallurgical processes
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