Sunday, November 12, 2006
- Symbol= Pb
- Atomic Number= 82
- Mass Number= 207.2 amu
History
Lead was one of the first metals to be discovered by man. Although, the exact date of discovery is still unknown. Historians believe the first dicoveries were in 3500 B.C. in Egypt. The oldest piece of lead dates back from 3800 A.D. and is found in the British Museum.
Process
Lead is not man made but the process of making the mineral pure is produced by man. First, lead ore is extracted from lead mines and then crushed. The ore is then treated using extractive metalurgy which is teh process of sepreating metals from the ore. The concentrate can range from 50% to 60% lead. Once the lead concenrate is dried then it is treated using pyrometallurgy. Pyrometallurgy is the technique of refining ores with heat to accerate chemical reactions. Then the lead is sinstered and then smelted to produce a high lead concentrated. Once the lead is cooled the lighter impurities rise to the surface and are removed. After, it is refined and smelted again to take out any more impurities. Finally, 99.9% lead is produced.
Uses
- Lead is used as a coloring element in ceramic glazes, mostly colors red and yellow.
- Used as a shielding from radiation.
- Lead sheets are used as roofing materials.
- Lead is the traditional base metal of organ pipes, mixed the varying amounts of tin to contol the tone of the pipe.
- Lead is added to brass to reduse machine tool wear.
- Lead is used in scuba diving weight belts to counteract the natural buoyancy of the neoprene wetsuits.
Relevant Facts
- Lead is found in mines approximately 1-2 miles under the Earth's suface.
- Lead is a posionous metal that can damage nervous connections which could result blood and brain disorders.
- If you are exposed to lead for a long time it can cause nephropathy. Nephropathy is any disease of the kidney.
- Lead- white paint has been withdrawn from sale in industralised countries because lead exposure has been linked to schizophrenia and retardation amongst children.
- Lead could enter soil and through (leaded) gasoline leaks from underground storage tanks causing issues everywhere.
http://en.wikipedia.org/wiki/Lead
