Extraction of zinc
- 1. Extraction of Zinc Presented by Nikhil Koshy Jacob ME Industrial Metallurgy 14MY33
- 2. Introduction • Zinc is mainly used for Galvanizing Production of alloys Dry cell batteries • Its minerals are Sphalerite (ZnS) Zincite (ZnO) Smithsonite (ZnCO3) Franklinite (ZnO(Fe,Mn)2O3 )
- 3. Sphalerite Zincite Franklinite Smithsonite
- 4. Pyro metallurgical extraction of Zinc Jkkkkkkkkkkk
- 5. Procedures • The ore is first ground and subjected to froth flotation • The concentrate obtained is subjected to roasting • Roasted oxide is ground and agglomerated and then sintered at 1200 in a Dwight Lloyd sintering and sent for retort reduction
- 6. • ZnO is reduced by carbon • Make sure CO partial pressure is maintained to prevent reverse reaction • Zinc vapour obtained is condensed at 4500c to form liquid Zn • Zinc condensation has to be carried out quickly to prevent formation of blue oxide of Zn+ZnO
- 7. Hydro metallurgical extraction of zinc
- 8. Procedures • Dissolution of zinc calcine in sulphuric acid • Precipitation of Cd by adding zinc dust to the leach solution i.e cementation • Precipitation of cobalt from leach solution by adding alpha nitroso – beta naphthol • Adjust the pH of leach solution to 5.3 to hydrolyze Fe and Al and add of MnO2 to oxidize iron to trivalent state to produce a precipitate that can absorb As, Sb, and Ge • Do electrolysis of filterate solution
- 9. Imperial Smelting Process J,h
- 10. Advantages of ISP • Its possible to simultaneously smelt low grade complex mixed charges to recover both Zn and Pb • Recovery of Zn is less expensive • A wide variety of furnace sizes are available • Furnace operation is fully automated • The mechanism is highly robust
- 12. Procedures • Preheated coke and sinter is charged from the top of the furnace • The lead becomes liquid metal and flows to the bottom of the furnace collecting precious metals like gold , silver etc (lead bullion) • Slag and lead bullion at the bottom can be separated because of their density differences • The furnace gases produced flows upwards to the condensers • Zinc and lead are collected after condensation
- 14. Procedures • The condensers perform two functions ie cool the furnace gases, help in dissolving the condensed Zn in molten lead • The rotors produce a spray of lead bath • Zn is cooled rapidly and goes in to the solution with lead • Zinc containing lead is pumped out of from the condensers and cooled • During cooling the lead becomes saturated with zinc and excess zinc emerges from the lead and floats on the surface • Zinc is separated and the lead is fed back to the condensers
- 15. Zinc from Lead Slags by Slag Fuming • Slag produced in the blast furnace have considerable amount of zinc in it • The slag is fed to a slag fuming furnace • The following reactions take place • The ZnO fumes are collected in bags and sent for Zn recovery to a zinc plant