History
Lead is a naturally occurring element found in small amounts in the earth’s crust. It can be found in all parts of our environment - the air, the soil, the water, and even inside our homes.[1]The oldest known lead article is a figurine found in Egypt that dates back to 4,000BC. Later, because of its outstanding properties, lead was used extensively by the Romans for water pipes, aqueducts, tank linings and cooking pots and then by ancient scientists in early cosmetics, paints and pigments, and in lead-rich glazes. [2]
Process Route
More than 95% mined lead comes from ores, that is, Galena (PbS), Cerussite (lead carbonate) and Angle site. There are only 4% recoverable lead in ores, so lead from reclaimed batteries accounts for more than half of the total.[3] The main recycling process including 3 steps: lead battery breaking and separation, metal lead reduction, and lead refining.[4]Mining and concentrating from ores also contains 3 steps: flotation separation, extraction, refining.[5]
Manufacturing
Concerning of the relatively low strength and hardness, deformation is easy to be formed. As a result, some common manufacturing processes of lead are cold stamping, rolling, extrusion, die casting and joined by welding, etc. For cold rolling, it can accomplish a good dimensional accuracy and surface finish. In this process, sheet or strip is introduced between rollers and then compressed and extruded.
Applications
Lead metal has several useful mechanical properties, including high density(bullet), low melting point, ductility, relative inertness, effectively absorbing electromagnetic radiation of short wavelengths(protective shielding), and relatively easier to extract from parent ores.[6][7] The largest application of lead is the manufacture of storage batteries. It has also been used for bullets since the Middle Ages.[8]If its major uses is in the glass of computer and television screens, where it shields the viewer from radiation. Concerns have been raised that lead bullets used can damage the environment.[9]
References
[1]https://www.epa.gov/lead/learn-about-lead. [online]Retrieved by (05/09/2019)
[2]https://www.ila-lead.org/lead-facts/history-of-lead.[online]Retrieved by (05/09/2019)
[3]https://www.britannica.com/technology/lead-processing.[online]Retrieved by (05/11/2019)
[4]http://lead.stcitaly.com/lead-battery-recycling-process/pyrometallurgical-lead-reduction-in-rotative-furnaces.html.[online] Retrieved by (05/11/2019 )
[5]https://www.britannica.com/technology/lead-processing#ref82077.[online]Retrieved by (05/13/2019)
[6]lead | Definition, Uses, Properties, & Facts (2019). [online]Available at< https://www.britannica.com/science/lead-chemical-element> Retrieved by (05/04/2019)
[7]Chemical properties of lead - Health effects of lead - Environmental effects of lead (2019). [online]Available at< https://www.lenntech.com/periodic/elements/pb.htm> Retrieved by (05/04/2019)
[8] https://www.wordhippo.com/what-is/sentences-with-the-word/bullets.html. Retrieved by (05/04/2019).