Introduction to Lead
Lead is one of the seven metals known from very ancient times. An early acquaintance of man with lead was favored by the ease of reduction of the metal from ores, its low melting point and ductility, which facilitated it's working. Lead is more metallic in properties while its oxides are amphoteric. Lead is a versatile metal with a wide range of applications.
Our earliest knowledge of smelting methods is speculative.
By 1900 technology was well advanced making use of PbS - PbO roast reaction and reduction reactions. From 1900 to the present, the technology and knowledge of smelting and refining process were improved to their present levels.
At present lead is recovered from
Primary Raw Materials likea) Galena - Lead Sulphide
b) Cerussite - Lead Carbonate
c) Minimum - Lead Oxide
Secondary Raw Materials liked) Scrap Batteries
f) Residues, Ash, Pastes etc.
For the recovery of Lead from the above raw materials different processes are followed, 1i.e. from Blast Furnace to Rotary Furnace.
By far the greatest use of Lead today is for the manufacture of Lead-Acid batteries.
Lead-Acid Batteries consume about 75 - 80 % of the world's Lead production and this represents the single largest application for Lead and Lead alloys. DUE TO EASE OF RECYCLING LEAD-ACID BATTERIES SUPPORT A THRIVING SECONDARY INDUSTRY.
The production of Lead chemical compounds occupies second place among its consumers after the battery industry. In industrialized countries 15 - 20 % of Lead is consumed for these purposes. Lead chemical compounds are used in the products of special types of glass, crystals, paints, PVC plastics stabilizers etc.
Cable and other industries consume about 5 - 10 % of the Lead production.
Product & Characteristics
- » Pure Lead or Refined Lead will be of 99.97 or 99.99% Purity.
- » Other major impurities associated with lead are Bismuth, Silver, Copper, Antimony, Tin, Arsenic, Sulphur, Nickel, Chromium, Zinc, and Cobalt etc
- » The total of these impurities will be less than 0.01 or 0.03 depending on the purity of the end product.
I. Battery Alloys :
There are different types of Lead alloys being used by Battery Manufacturers, a
few of which are given below.
1) Antimonial Lead with selenium as a grain refiner for grids.
2) Antimonial Lead with copper and sulphur as grain refiners for grids.
3) Antimonial Lead for small parts.
4) Lead-Calcium alloys for grids.(0.4% - 1.5% Tin content.)
5) Lead-Antimony - Cadmium alloy.
There are many more types of battery alloys being used by different Battery Industries.
II. Cable Alloys:
1. Lead alloy with 0.20 Antimony and 0.4% Tin for power cables.
2. Lead alloy with 0.80 - 0.95% antinomy for telephone cables (at present use of this type of alloy is reduced.)
3. Lead alloy with 0.14 - 0.16 % Cadmium, Tin 0.35 - 0.45 % for electric cables.
4. Lead Alloy with 0.02 - 0.04 % Calcium, Tin 0.30 - 0.40 % for electric cables.
III. Lead Lining :
Pure Lead and Pure Lead with Copper
Closed Cycle of Lead
Lead is an example of an environmental success story. Industry over the years has defined several efficient processes to extract and purify lead from lead scrap. The finished product is indistinguishable from virgin lead. Lead is processed into lead/acid batteries. At the end of their service life, lead is once more extracted from the battery, purified, and returned to service in another new lead/acid battery.
Since lead is the major component of a lead/acid battery, and the most prevalent use of lead is in the manufacture of lead/acid batteries, it in turn follows that the future of the demand cycle for lead and its alloys is closely allied with market considerations for the lead/acid battery.