-Zinc blend: (Main Ore)
-It can be extracted by two different methods:
i) Carbon reduction process
ii) Electrolyte process
-We discuss Carbon Reduction Process only.
-Ore is crushed by jaw crusher and pulverized( powder) using ball mills.
-As zinc blend is sulphide ore, it is concentrated by froth floatation.
-Pine oil or Eucalyptus oil acts as the frothing agent.
-The sulphide ore is deposited on surface as froth.
-Since, it is sulphide ore, the ore is roasted i.e. heated at excess supply of air.
-During heating, some are also converted to .
-If Calamine ore was there calcination was done:
During roasting, volatile impurities are removed as oxide.
-Roasted is heated with carbon in furnace to reduce oxide to metallic form.
Different reduction process are employed. They are:
a) Vertical Retort Process
b) Belgian Process
c) Silesian Process
-As vertical retort process is economical and modern process, it is used.
-In this process ZnO and Coke in ratio is taken and heated by burning Producer Gas at about .
-In this condition, Zinc oxide is reduced to zinc which vaporizes.
-The vapor of Zinc and after reduction is passed through condenser after release of volatile impurities called Spelter Zinc.
-The fresh charge is added continuously from charging door and residual waste material is taken out from bottom.
-Impurities like Pb, Fe, Cd, etc are present which can be purified by:
-Zinc metal is melted on the sloping hearth of reverberatory furnance.
-Molten zinc flows down leaving non-fusible impurities.
-Distillation at separates having low boiling point than etc. having higher bpt and distillation at separates from zinc .
-Displace from non-oxidizing acid.
-Process of coating zinc over the surface of iron in order to protect it from rusting.
-It is done by following process:
1) Cleaning of the article:- By sand blasting and dipped on dil. HCl or H2SO4 to remove any oxide film and rinsed with water.
i) Ordinary Galvanization:
-Process in which iron steel is dipped into molten zinc for coating.
ii) Heated Galvanization:
-Process in which iron sheet is dipped into molten zinc for coating.
-It is the method in which electroplating is performed for galvanization.
-Zinc obtained by dropping molten zinc in cold water is called granulated zinc.