Product
colour:silvery white
Type:
Lead is usually found in ore with zinc, silver and (most
abundantly) copper,
and is extracted together with these metals. The main lead mineral is galena (PbS), which
contains 86.6% lead. Other common varieties are cerussite
(PbCO3) and anglesite (PbSO4).
Listing
Description:
Lead is a main-group element
with symbol Pb (Latin: plumbum) and atomic
number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a
bluish-white color after being freshly cut, but it soon tarnishes to a dull
grayish color when exposed to air. Lead has a shiny chrome-silver luster when
it is melted into a liquid.Lead is used in building construction, lead-acid
Detailed Description:
Lead
is used in building construction, lead-acid
batteries, bullets
and shot,
weights, and is part of solder, pewter, fusible alloys. and radiation
shielding. Lead has the highest atomic
number of all of the stable elements, although the next higher element, bismuth, has a half-life
that is so long (much longer than the age of the universe) that it can be
considered stable. Its four stable isotopes have 82 protons; a
"magic number" in the nuclear shell model of atomic
nuclei.
Lead
is a poisonous substance to animals. It damages the nervous
system and causes brain
disorders. Excessive lead also causes blood disorders in mammals. Like the
element mercury, another heavy metal, lead is a potent neurotoxin
that accumulates both in soft tissues and the bones. Lead
poisoning has been documented from ancient
Rome, ancient Greece, and ancient
China.
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Characteristics
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Lead
is bright and silvery when freshly cut but the surface rapidly tarnishes in air
to produce the commonly observed dull luster normally associated with lead. It
is a dense, ductile, very
soft, highly malleable, bluish-white metal that has poor electrical conductivity when compared to
most other metals. This metal is highly resistant to corrosion,
and because of this property, it is used to contain corrosive liquids (for
example, sulfuric acid). Because lead is very malleable and
resistant to corrosion it is extensively used in building construction – for
example in the external coverings of roofing joints.
Metallic
lead can be toughened by addition of small amounts of antimony, or of
a small number of other metals such as calcium. All isotopes of lead,
except for lead-204, can be found in the end products of the radioactive
decay of the even heavier elements, uranium and thorium.
History
Lead has been commonly used for thousands of years because it is
widespread, easy to extract and easy to work with. It is highly malleable and
ductile as well as easy to smelt. Metallic lead beads dating back to 6400 BC have been
found in Çatalhöyük in modern-day Turkey.[7]
In the early Bronze Age, lead was used with antimony and arsenic. Lead is
mentioned in the Book of Exodus (15:10).
The
largest preindustrial producer of lead was the Roman
economy, with an estimated output per annum of 80,000 t, which was
typically won as a by-product of silver smelting.[8][9][10]
Roman
mining activities occurred in Central
Europe, Roman Britain, the Balkans, Greece, Asia Minor;
Hispania
alone accounted for 40% of world production.[8]
Roman
lead pipes often bore the insignia of Roman emperors (see Roman lead pipe inscriptions). Lead
plumbing in the Latin West may have been continued beyond the age of Theoderic the Great into the medieval period.[11]
Many Roman "pigs" (ingots) of lead figure in Derbyshire lead mining history and
in the history of the industry in other English centers. The Romans also used
lead in molten form to secure iron pins that held together large limestone
blocks in certain monumental buildings. In alchemy, lead was
thought to be the oldest metal and was associated with the planet Saturn.
Lead's
symbol Pb is an abbreviation of its Latin name plumbum for soft metals; originally it was plumbum
nigrum (literally, "black plumbum"), where plumbum
candidum (literally, "bright plumbum") was tin. The English words
"plumbing",
"plumber",
"plumb", and "plumb-bob" also derive from this Latin root.
Occurrence
Metallic
lead does occur in nature, but it is rare. Lead is usually found in ore with zinc, silver and (most
abundantly) copper,
and is extracted together with these metals. The main lead mineral is galena (PbS), which
contains 86.6% lead. Other common varieties are cerussite
(PbCO3) and anglesite (PbSO4).
Ore processing
Most
ores contain less than 10% lead, and ores containing as little as 3% lead can
be economically exploited. Ores are crushed and concentrated by froth
flotation typically to 70% or more. Sulfide ores are roasted, producing primarily lead oxide and a
mixture of sulfates
and silicates
of lead and other metals contained in the ore.
Lead
oxide from the roasting process is reduced in a coke-fired blast
furnace.[13]
This converts most of the lead to its metallic form. Three additional layers
separate in the process and float to the top of the metallic lead. These are slag (silicates
containing 1.5% lead), matte (sulfides containing 15% lead), and speiss (arsenides
of iron and copper). These wastes contain concentrations of copper, zinc,
cadmium, and bismuth that can be recovered economically, as can their content
of unreduced lead.
Metallic
lead that results from the roasting and blast furnace processes still contains
significant contaminants of arsenic, antimony, bismuth, zinc, copper, silver,
and gold. The melt is treated in a reverberatory furnace with air, steam, and
sulfur, which oxidizes the contaminants except silver, gold, and bismuth. The
oxidized contaminants are removed by drossing, where they
float to the top and are skimmed off.
Most
lead ores contain significant concentrations of silver, resulting
in the smelted metal also containing silver as a contaminant. Metallic silver
as well as gold is removed and recovered economically by means of the Parkes
process.[2][12][14]
Desilvered
lead is freed of bismuth
according to the Betterton-Kroll process by treating it with
metallic calcium and magnesium, which forms a bismuth dross that can be skimmed
off.[12][14]
Very
pure lead can be obtained by processing smelted lead electrolytically by means
of the Betts process. The process uses anodes
of impure lead and cathodes of pure lead in an electrolyte of silica fluoride.
Applications
Due
to its half
life of 22.2 years the radioactive isotope 210Pb
is used for dating material from marine sediment cores
by radiometric methods.
Elemental Lead
Because
of its high density and resistance from corrosion, lead is used for the ballast
keel of sailboats. Its high density allows it to counterbalance the heeling
effect of wind on the sails while at the same time occupying a small volume and
thus offering the least underwater resistance. For the same reason it is used
in scuba
diving weight belts to counteract the diver's
natural buoyancy and that of his equipment. It does not have the
weight-to-volume ratio of many heavy metals, but its low cost increases its use
in these and other applications.
Lead
is used in applications where its low melting point, ductility and high density
is an advantage. The low melting point makes casting of lead easy, and
therefore small arms ammunition and shotgun pellets can be cast with minimal
technical equipment. It is also inexpensive and denser than other common
metals..[19 The hot metal typesetting uses a lead based alloy
to produce the types for printing directly before printing.
Its
corrosion resistance makes it suitable for outdoor applications when in contact
with water.
More
than half of the worldwide lead production is used as electrodes in the lead-acid
battery, used extensively as a car battery.
PbO2 + 4 H+
+ SO42- → PbSO4 + 2 H2O
Lead
is used to form glazing bars for stained
glass or other multi-lit windows. The practice has become less common, not
for danger but for stylistic reasons. Lead, or sheet-lead, is used as a
sound deadening layer in some areas in wall, floor and ceiling design in sound
studios where levels of airborne and mechanically produced sound are targeted
for reduction or virtual elimination.[22][23]
Lead
is used as shielding from radiation (e.g., in X-ray rooms).[24]
Molten lead is used as a coolant (e.g., for lead cooled fast reactors).[25]
Lead
is the traditional base metal of organ pipes,
mixed with varying amounts of tin to control the tone of the pipe.[26][27]
Lead
is used as electrodes
in the process of electrolysis. Lead is used in solder for
electronics, although this usage is being phased out by some countries to
reduce the amount of environmentally hazardous waste. Lead is used
in high voltage power cables as sheathing material to prevent water diffusion
into insulation. Lead is added to brass to reduce machine
tool wear. Lead, in the form of strips, or tape, is used for the
customization of tennis rackets. Tennis rackets of the past sometimes had lead
added to them by the manufacturer to increase weight.[28]
Lead
has many uses in the construction industry (e.g., lead sheets are used as architectural metals in roofing material,
cladding, flashing, gutters and gutter joints, and on roof parapets). Detailed
lead moldings are used as decorative motifs used to fix lead sheet. Lead is
still widely used in statues and sculptures. Lead is often used to balance
the wheels of a car; this use is being phased out in favor of other materials
for environmental reasons.
Lead Compounds
Lead
compounds are used as a coloring element in ceramic
glazes, notably in the colors red and yellow.[29]
Lead is frequently used in polyvinyl chloride (PVC) plastic, which coats
electrical cords.
Lead
is used in some candles to treat the wick to ensure a longer, more even burn.
Because of the dangers, European and North American manufacturers use more
expensive alternatives such as zinc.[32][33]Lead glass
is composed of 12-28% lead oxide. It changes the optical characteristics
of the glass and reduces the transmission of radiation.
PRICE
$9/KG
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