2. WHAT IS EXTRACTIVE METALLURGY?
Extractive metallurgy is a branch of metallurgical engineering wherein
process and methods of extraction of metals from their natural mineral
deposits are studied.
Types of Extractive Metallurgy
1. Pyrometallurgy
2. Hydrometallurgy
3. Electrometallurgy
3. Properties of Lead:
Soft , mealleable, metallic solid
Bluish-gray in color
Rarely found pure in nature
Reacts vigorously with fluorine at room temperature
Reacts well with chlorine when warmed
Melting point (327.43 degree)
Boiling point(1740 degree)
4. Continue….
• The true metal is very resistant to corrosion
• Lead can be toughened when Sb, antimony, is added
• The normal state of Lead ,is a solid state of matter
• Lead has 82 protons,82 electron and 125 neutrons.
• Deflects radiation
• Poor conductor of electricity
5. History
• Lead has been around for thousands of years
• Uses of lead can be traced back to the Bronze age(7000-5000 B.C)
• The word “plumbing” is derived from the Latin root, plumbum, Which
is the name for lead
• The Romans at the first of the Caesars were probably the first to
realize the industrial potentialities of lead
6. Health Effects
Damage most organs
Death can occur at extremely high levels
Toxic in nature
Renal toxicity- kidney damage
Hepatic damage- lever damage
Cognitive development in children
7. LEAD ORES:
• Most important by far is galena,an easily recognized, brightly
metallic material
• Commercial importance – lead minerals, cerusite, lead carbonate,
anglesite
• Various in richness from as low as 2% to value exceeding 20% lead,
with the average closer to the lower value
OCCURANCE
U.S.A, Mexico, Australia, Canada, U.S.S.R.,U.K
8. Ore Dressing
• is the process of separating commercially valuable minerals from
their ores
• Flotation Process is generally used in ore dressing process
• Crushed ore are diluted with water (4 Times)
• The mass agitated in a tank which contains air.
• As agitation, the ore is formed at the top of the tank & valueless
gangue matter remains unaffected at the bottom.
• The forth flows from the tank and easily dried.
9. Size Reduction:
• The processes of size reduction involve the breakage or fracture of
particles.
• For large ore, the ore is taken to the crushing and grinding section.
• For small ore, crushing and grinding doesn’t need because lossing of
energy, then fine grinding can be allowed for small ore in size.
10. ROASTING or SINTERING
ROASTING :The galena is roasted in order to remove Sulphur
component of the metal sulphide. Sulphur dioxide gas can then be
cleaned and used to make sulphuric acid.
SINTERING : The lead(II) oxide is heated and made into lumps, a
process known as sintering
For roasting galena lead ore,
Huntington heberlein Roasting process
Dwight – Lloyd Sintering Machine
11. Huntington Heberlein Roasting Process
• Partially Roasted ( shulphide ore + lime )
• Air through perforated gate
• Oxidising action ( PbS PbO )
• For quick roasting the cast iron pot rotates backward and forward
2PbS + 7O PbO + PbSO4 + SO2
12. Dwight Lloyd Sintering Machine
• Suitable for fine concentrates obtained by ore dressing & containing
high Sulphur ( > 16% )
• Two sintering machines are employed.
• The lumps are crushed & sorted to a suitable size for subsequent
treatment in a blast furnace, similar in construction to those for
making iron but smaller.
14. SMELTING
• Smelted with coke ( 8% to 13%) & flux in the lead blast furnace
• Coke is added for two purposes 1. reducing agent
2. a source of heat
• Limestone provides material for the flux containing the salg &
impurities.
• Mixture is fed at the top of the blast furnace, lead oxide (II) is reduced
PbO(s) + C(s) Pb(I) + CO (g)
PbO(s) + CO(g) Pb(I) + CO2 (g)
15. • The molten lead is tapped off from the base of furnace & cast into,
typically 4 tonne ingots or put into a holding kettle which keeps the
metal molten for refining process.
• The product contains about 99.5% lead, the remaining 0.5% being
mostly antimony, silver with smaller amounts of other metals.
• Because it contains silver and gold at this stage ,the lead is referred to
as bullion lead.
17. Parkes process
• The parkes process is a pyrometallurgical industrial process for removing
silver from lead during production of bullion.
It is an example of liquid-liquid extraction.
• Most widely used refining process
• The process takes advantage of two liquid-state properties of Zinc.
First, zinc is immiscible with lead
Second is that silver is 3000 times more soluble in zinc than it is in lead
18. Betts Process
• Electrolysis process. Use with bullion high in bismuth. Bismuth is
removed & recovered, which is not the case with parkes process.
• Lead is taken up by electrolyte from the anode & deposited on the
cathode, the impurities remaining behind on the anode.
• Lead of purity 99.99 percent is produced by this process.
19. Product & By Products
• When the lead has been sufficiently refined, it is cooled & cast into blocks
which may weigh as much as a ton, this is finished product.
• By Product : The gangue, waste rock etc.
• Waste is not considered by the industry to be an environmental hazard.
• It can be pumped into a disposal pond which resembles as a natural lake.
• Sulfuric acid is the major byproduct of the smelting process. To protect the
atmosphere, fumes and smoke are captured, the air released by the plant
is first cleaned. The Sulphur dioxide is collected at a separate acid plant &
converted to sulfuric acid.
• The refinery can sell this acid as well as its primary product, Lead itself
