LEAD(Plumbum)

Pb

LEAD

Chemical symbol : Pb Atomic number : 82 Atomic weight : 207.2 Group no.: 14 (or IVa) Element of origin name:

Anglo-Saxon lead

82

Pb

HISTORY Lead has been commonly used for

thousands of years ago. Came from the Latin word “plumbum” Lead was mentioned on the Book of

Exodus (15:10)

“But you blew with your breath,

and the sea covered the

They sank like lead in the mighty water”

In alchemy , lead was thought to be the oldest metal associated with the planet Saturn.

Romans used lead in the molten form to secure iron pins that held together large limestone blocks in a certain monumental building.

SOURCES OF LEAD

Galena(PbS)

is a grayish-black cubic crystals which is

composed of 86% Pb and 13.5% S. It is the principal

ore of lead.

Cerrusite (PbCO3 )

Is a colorless, white or gray ore which is

composed of 83.5% of PbO and 16.5 % of CO2

It is also known as white lead ore.

PbSO4

is a colorless, white gray, pale shades of

yellow; colored dark gray by impurities which

composed of 73% PbO and 26.4% SO3

PHYSICAL PROPERTIES

Malleable and ductile Easy to scratch and cut Has a little tensile strength Corrosion resistant Melts at 327 oC Boils atb1750 oC Specific gravity: 11.45

CHEMICAL PROPERTIES Exhibit variety of oxidation number (+2,+4) Reaction with air

2Pb + O2 2PbO

Reaction with dilute acid

2Pb + H2SO4 PbSO4 + H2

Reaction with organic acid

Pb + 2CH3COOH Pb(CH3COOH)2+ H2

Reaction with pure H2O in the presence of O2

2Pb + 2H2O + O2 2Pb(OH)2

Reaction with pure H2O in the presence of CO2

3Pb + 2CO2 + 4H2O Pb3(OH)2(CO3)2 + H2O

ADDITIONAL INFORMATIONMetallic lead is resistant to the action of dilute to moderately concentrated solution of sulfuric acid because of the formation of coatings of insoluble lead sulfate.Hard water does not affect lead because of the formation of surface layer of insoluble compound of PbSO4, bicarbonate and other anion that is usually present in hard water .

CRUSHER

GRINDER

ore

Crushed ore

Ground ore

Xanthale rgt.

air gangue

ROASTER

froth

SO2

air

Unroasted (PbS)PbSO4

PbO

Reactions: At the Roaster:

2PbS + 3O2 2PbO + 2SO2

2PbS + 2O2 PbSO4

Extraction process

BLAST FURNACE

MELTER

COOLER

Unroasted (PbS)

PbSO4

PbO

Crude Pb

SO2,CO2,CO, FeS

SlagCaSiO3

Coke, scrap Fe, CaCO3

I. Spark ProcessA. Removal of Cu, Sb, As and

Bi

Melted Pb

Crystallized Cu

Oxides of Sb, As, Bi

(skimmed off)

Blast air

Reaction at the Blast furnace

2PbO + PbS 3Pb + 2SO2

PbSO4 + PbS 2Pb + 2SO2

PbO + C Pb (s) + COPbO + CO Pb (s) + CO2PbS+ Fe Pb (s) + FeS (g)

Pb free of Sb, As and

Bi

MELTERELECTRO-REFINERY

B. Removal of Au and Ag.

Pb free of Sb, As and Bi

Au and Ag

dissolve in Zn

zinc

II. Betts Process

High purity Pb metal

Impure lead

Applications Major constituent of lead acid storage battery. Used as a coloring pigment. Used as sound deadening layer. Used as solder for electronics. Use as roofing materials. Used as shield against radiations. Used as a pigment in lead paint for white as well as

yellow and red color.

Alloys

A. Perforated grids in storage battery

- 4% Pb, 12% Sb, 0.25% Sn and small amount of arsenic, silver and copper.

B. Solder

- 50 % Sn and 50% Pb.

C. Bearing Metal

-10% -90% Pb with Sn, Sb, and Cu.

D. Type metals

- example is the metal in the linotype machine composed of 84.5% lead, 45% tin and 11.5% antimony.

- used in printing industry.

E. Pewter

- 1%-50% Pb and Sn

II

Sheet lead is used for making the chambers of sulfuric plants for which it is chemical inactivity make it suitable. Also used as a roofing material.

Lead foil is used for lining tea chests, and as as substitute for tin foil.

Lead shot is usually has 1 % arsenic added to make lead harder.

Lead pipe is used for sink traps and waste pipes.

Important Compounds Lead (II) oxide (PbO) or litharge

a red or reddish yellow solid used in making glass, paint and varnish industry.

Lead (IV) oxide (PbO2)

a brown color substance and forms the active material of the positive plate of lead storage battery.

Lead (II,IV) oxide (2PbO.2PbO2)

known as red lead, used as a protective pigment of paint for iron and steel.

Lead (II) acetate (Pb(C2H3O2)2)

white crystalline used as white lead and to treat poison ivy poisoning.

Lead (II) chromate PbCrO4

chrome yellow used as a yellow pigment. Lead (II) arsenate Pb3(AsO3)2

called as arsenate lead. White colored substance, used as an insecticide.

Basic lead (II) carbonate (Pb3(OH)2. (CO3)2 or white lead

used as a paint base. Tetraethyl lead (Pb(C2H5)4 or TEL

colorless liquid used as an antiknock additive in aviation of gasoline.