Lead | Metallurgical process | Extraction

Metallurgy Process of Lead
Monday, November 12, 2012
By: Maheen , Arfa & Maryam
Lead is a very bright and silvery blue metal in a dry atmosphere. It has a few characteristic properties such as high density, softness, ductility and malleability. In comparison to other metals, Lead is a poor conductor of electricity but it has a high ability to react with organic chemicals. Native Lead was found in Sweden, but it is rare to have the element alone in nature. It’s usually found in ore with zinc, silver, copper and it’s extracted together with these metals. The most significant lead mineral is Galena, also known as Lead Sulfide.
Lead Sulfate and Lead Carbonate are also two other lead based minerals. The Lead ore crushing process can be preceded with these commonly used crushers and grinding mills; jaw crushers, cone crushers, hammer crushers and ball mills. Typically, primary crushing takes place at a mine site. It can only be accomplished by using a jaw crusher or a cone crusher. The primary crushing chunks the ore in to about 6 – 10 inches. Over size material is passed through additional crushers and classifiers to achieve a much smaller particle. The ore then goes through another process at a secondary milling facility to obtain smaller lead ores. These smaller lead ores are then fed into a mill such as a ball mill for grinding.
Dressing is the process of sorting out the raw materials extracted from the mine. It then needs to be cleaned up before smelting. Once a pile of pure Galena is produced the lumps have to be reduced in size to about a size of a pea. Once the pure ore is reduced to a suitable size, it is then transported to the nearest Smelt Mill. The process of extracting a metal in the state of fusion is called smelting. In this process the ore is mixed with carbon, obtained after the above reactions. A flux is added during the operation to convert the gangue to a fusible slag. Slag floats on the metal and protects it from oxidation. Metallic oxide is reduced by carbon and the metal may be obtained in the molten state or as condensed vapors. Lead is obtained by this process.
Lead has many different kind of uses. It is a major component of the lead acid battery and is mainly used in car battery. It is used for ballast keel of sailboats and scuba diving weight belts, due to its high density. Lead Sulfate, Lead Chromate and White Lead are used as coloring elements in paints and ceramic glazes. Lastly, lead can also be used for the lining of chemical treatment baths, acid plants and storage vessels.
Lead is a very dangerous poison for children when it is inhaled or ingested. For children under six, Lead can cause learning disabilities, behavior issues and kidney damage. In adults Lead exposure may increase chances of illness during pregnancy and may cause nerve disorders.

References:
“Lead and Its Human Effects.” Lead and Its Human Effects. N.p., n.d. Web. 07 Nov. 2012. <http://www.kingcounty.gov/healthservices/health/ehs/toxic/LeadGeneral.aspx>.
“Lead Refinery.” Processes -. N.p., n.d. Web. 07 Nov. 2012. <http://www.metsoc.org/virtualtour/processes/zinc-lead/lead.asp>.
“Gangue.” Wikipedia. Wikimedia Foundation, 26 Oct. 2012. Web. 07 Nov. 2012. <http://en.wikipedia.org/wiki/Gangue>