2. Introduction about the Company:-
• Hindustan Zinc Limited (HZL) is an
integrated mining and producer of zinc ,
lead , silver and cadmium.
• On 10th January 1996 Hindustan Zinc
Limited was declared as a Public Sector
• HZL is world’s lowest cost zinc producer.
• HZL operates world’s 3rd largest open pit
mine and world’s largest zinc mine in
Rampura Agucha, Rajasthan.
• HZL annually produces 10,00,000 tonnes
of refined Zinc and Lead.
4. Q. Why do we need Zinc?
Galvanizing Die Casting Brass Bronze Rolled Zinc Chemicals Others
5. HZL, Debari Udaipur
▪ Location – situated at 14 km from udaipur
▪ Products :- high grade zinc , Cadmium and Sulphuric acid
▪ Raw material Suppliers : 1. Zawar mines (Udaipur)
2. Agucha Mines (Ajmer)
3. Dairba mines (Rajsamand)
Basic Plants of the Process:-
▪ 1. Acid and Roaster plant
▪ 2. Leaching and purification
▪ 3. Zinc Electrolysis
▪ 4. Melting And cooling
6. Acid & Roaster Plant
▪ Roasting is a process of oxidizing zinc sulphide concentrates at high
temperatures into an impure zinc oxide, called Zinc Calcine.
▪ ZnS + 3/2 O2 ZnO + SO2
▪ Then ZnO is sent to Leaching process and SO2 is sent to Acid formation
▪ Acid plant conversion Reaction
▪ So2 + 1/2 O2 SO3
▪ The formed SO3 is transferred to IAT and FAT for final acid formation
7. LEACHING AND PURIFICATION
▪ Leaching is dissolving the calcine in a solution of sulphuric acid to form zinc
ZnO + H2SO4 ZnSO4 + H2O
The solid residues separated from the leaching process still contain substantial
amount of zinc and some amount of lead, silver and other impurities
Solids are leached with strong, often hot, sulphuric acid, dissolving most of the
remaining zinc together with iron and other impurities.
MeO + H2SO4 MeSO4 + H2O
The solution removed are CdSO4, CuSO4 and CoSO4, for getting a pure ZnS04
This is cleared solution is sent to filter press where the clear solution of ZnS04 is
sent to zinc electrolysis segment along with Sulphuric Acid.
8. Electrolysis: -
• This is the heart of the cell house.
It is made up of reinforced
concrete and is supported on
electric isolator on one side of the
cell and a PVC overflow box is
integrated on the other.
• The cell has about 8 meters length
1.4 width and 2.5 meter height it
cell contains 30 cathode and 31
Anode is made up of Lead Silver alloy and Cathode is made up of Aluminum. At Hindustan
zinc limited cell house uses 35 megawatt of electricity the total used electricity by Hindustan
zinc debari is 70 megawatt. Every 24 to 48 hours, each cell is shut down, the zinc-coated
cathodes are removed and rinsed, and the zinc is mechanically stripped from the aluminum
9. Melting and Casting :-
• Melting will be carried out in two identical
electric induction furnaces.The furnaces
will have melting rate of 22 tonnes per hour
• After melting, zinc totes are formed which
are further transferred to the open yard by
12. Raw Material Section
▪ Zinc is delivered by trucks and stored in two underground bins.
▪ From several belt conveyors that ore is transport to two hoppers .
▪ With the help of magnetic separator the material is transported into
▪ Here many nozzles are spraying water to add moisture to it.
▪ Then finally using belt conveyors and rotary table feeder .The roaster
13. Roaster Plant
• Roasting is a process of oxidizing zinc sulphide concentrates at high
temperature into impure zinc oxide.
Zinc Suphide Sulphur DioxideCalcine
14. Parts of Roaster Plant: -
1. Waste Heat Boiler
•The hot gas stream leaving the roaster is
drawn into the waste heat boiler under
suction from the SO2 blower.
•The waste heat boiler is a horizontal-
pass boiler , directly connected with the
gas outlet flange of the roaster.
•The boiler produces steam in a forced
circulation system and the dust-laden
gases are cooled down from the roasting
temperature to about 350°C
15. 2. Cyclone: -
The cooled and dust loaded gas enters
the two parallel cyclones for pre-
dedusting with a temperature of approx.
The gas leaves the cyclones at the top
whereas the dust is collected in the lower
part of the cyclones and removed via rotary
valves. Final dedusting of the hot gas is
achieved in the hot ESP.
16. Gas Cleaning Plant: -
3. Hot gas precipitator
• After passing through Cyclone the gas
passed through hot gas precipitator to
remove the fine particles of calcine by the
application of electric field.
4. QuenchingTower: -
• In the quench tower, the hot gas is cooled by
the evaporation of water.The heat of the
incoming gas (Temperature: > 300°C) is used
for the evaporation of water that is sprayed
into the QuenchTower.
17. 6. Packed gas cooling tower
▪ The cooling in the quench tower does result in Addition of moisture to SO2
▪ Removal of water vapour is done in a packed gas cooling tower.The gas
enters the tower from the bottom and flows upwardly through the packing.
7. Wet Gas Precipitate
▪ Final removal of dust and aerosols will be carried out in the wet electrostatic
▪ Here 2 parallel arrangement are present , so that the SO2 could me more
18. • In order to achieve an upgraded quality of Sulphuric Acid(H2SO4), the Gas Cleaning
Plant is equipped with a system for removal of excess MercuryVapour(Hg).
8. Mercury Removal: -
𝐻𝑔𝐶𝑙2 + 𝐻𝑔 −−→ 𝐻𝑔2 𝐶𝑙2
𝐻𝑔𝐶𝑙2 + 𝐶𝑙2 −−→ 2𝐻𝑔𝐶𝑙2
19. BASIC OPERATION OF ACID PLANT
1. DryingTower :-
• Gases are passed through drying tower from bottom to remove the moisture
by spraying Sulphuric Acid from top.
• By the use of concentration analyser, the concentration of circulating acid is
maintained in IAT(Initial AbsorptionTower) and FAT(Final Absorption tower).
2. SO2 Blower : -
• It is used to circulate SO2 bearing gases by the use of heat exchangers and
• It is assembled with an electric motor to transport the gas from gas cleaning
plant via Sulphuric Acid Plant.
20. 3. Converter Group and Preheater: -
• In Catalytic converter , conversion of so2
to so3 take place at 450c
• Preheater is use to heat the catalyst and
heat exchangers to increase efficiency of
• It is also used to preheat SO2 gas at
21. 4. AbsorptionTower: -
• After convertor group and preheater , the
gas is then flows in absorption tower,
where the final reaction takes place.
• The SO3 reacts with H2SO4 to make
H2SO4 and then this H2S2O7 is converted
into final H2SO4.
•This is how the sulphuric acid produced at
HZL, Debari ,Udaipur
In my 45 days training I learnt
▪ How the processes are going on in an Industry
▪ The Smelting Zinc from Zinc ore.
▪ The process making of Sulphuric Acid H2SO4.
▪ Also learn the inside process of Leaching , electrolysis , melting etc.