Define metallurgy.Name the steps involved in metallurgy.What are the various methods used for crushing and grinding and concentration of ore
Answers
various methods
froth flotation method
magnetic separation method
hydroelectric separation method
Metallurgy is large scale process for obtaining metals from their concentrated ore.
◼Dressing of ore.
In this impurities are removed from concentrated ore to obtain pure concentrated ore.
It can be done by 4 methods:-
▶Hydrolytic method
Separation of impurities due to its different density from ore.
▶Magnetic separation
Separating magnetic ore from non magnetic gangue or magnetic gangue from non magnetic ore.
▶Froth flotation
Seperation by preferential wetting.
▶Chemical method.
Separating impurities by adding chemicals.
◼Conversion of ore to its oxide
This can be done by two methods:-
▶Roasting
Heating of concentrated ore in presence of air before it reaches to its melting point.
▶Calcination
Heating of concentrated ore in absence of ore before it reaches to its melting point .
◼Converting oxides to pure metal by reduction
Methods depends on which place the metal lies in reactivity series.
▶For metals like K, Na, Ca, Mg and Al it is done by electrolysis.
▶For metals like Zn, Fe, Pb, H, Cu its done by using reducing agent.
▶For metals like Hg and Ag by thermal decomposition.
◼Obtaining pure metal from impure metals.
It is usually done by electro refining.
In electrolysis,
Impure metal is kept at anode
and pure metal is obtained at cathode and electrolyte too have ions of same metal.
Ore are crushed or grinded according to which metal they belong like
◼Zinc, iron etc are pulverised.
◼Silver and Gold are smelted.
◼Blasting
In this proccess the ore is converted to various sizes peices or chunks .
◼Crushing
In this process ore is converted into pieces or crushed by crushers, keeping them dry.
◼Grinding
In this process, various machine's are used to grind the ore the ore into fine particles.