The process used for the extraction of metals in their pure form  from their ores is referred to as metallurgy.

Methods of obtaining pure metals from their ores

1.Crushing and grinding of ore

2.Concentration of ore

3.Roasting,Calcination and smelting

4.Reduction

5.Refining of metals

Crushing and grinding of ore

Ores are crushed into a fine powder in big jaw crushers and ball mills.

This process is called pulverization

After pulverization,the ores are concentrated based on the type of impurities and their percentage proportions.

Concentration of ore

Concentration or centrifugation based on varying density 

Froth floatation Method

Magnetic separation

Centrifugation is done when there is difference between  the densities of  the ore and impurities

Denser ore particles settle in the grooves Lighter impurities rise to the water surface

and are separated

In this method,the powdered ore is placed on a moving table with slots(grooves)

and is moved rapidly .The dense ore particles settle down in the grooves,while the lighter  impurities are separated.

Froth floatation is used to concentrate ores that are in sulphide forms

Concentration of sulphide ores of copper.lead and zinc metal are carried out by froth floatation Method

ORE -Preferentially wetted by the oil and hence,floats on the top as foam  gangue-Preferentially wetted by the water and settles down

The ore is taken in a large tank containing oil and water and is agitated with a current 

of compressed air

(water containing pine oil)

The ore,wetted by the oil,separates from the impurities or gangue in the form of froth.Heavy particles like clay,sand,etc.Become wet and settle at the bottom.

The sulphide ore is removed with sieves in a second vessel and washed with water

In magnetic separation the pulverised ore is placed on a conveyor belt that has two magnetic wheels.

The magnetic particles are attracted to the magnetic wheels and separately apart from the non-magnetic particles

Conversion of ores to oxides

Methods of conversion of ores to oxides 

Roasting  Calcination Smelting

 Roasting is the process of heating the concentrated ore tp high temperature in presence of excess air

 Calcination is the process of heating the concentrated ore in absence of air at a temperature not sufficient to melt the ore.

 Smelting is a melting operation in which the constituents of the ore are in melted form.

 Methods of reduction of metallic oxides 

 1.Reducing agents

 2.Electrolysis 

 3.Thermal Decomposition

 Reducing agents like carbon or carbon  monoxide are used to reduce zinc.iron,lead and copper oxides.

 When oxides of metals like iron,manganes and chromium are heated with aluiminium,

 the corresponding metal is obtained by reduction.

 Electrochemical reduction method is used to obtain metals from oxides of active metals because these metals attract more oxygen than carbon.

 Methods of refining impure metals

 Electrolysis 

 Liquefaction 

 Distillation

 Metals like copper,zinc,tin,lead,chronium,nickel ,silver and gold are refined electrolytically.

 Liquefaction  is used for refining of metals like tin,lead etc.having low melting points

 In this method,a furnace having slope is kept slightly at higher temperature than the melting point of the metal.

 The metal melts and is collected in the vessel kept below.

 The melting points of impurities are higher and so do not melt and are found in the solid form on the slope .

 Crystallisation

 Silicon

 Boron

 The impurities are more solube in the molten form.so as the molten metal  in the form of crystals.

 The process used for the extraction of metals in their pure form from their ores is called metallurgy 

 Ores are crushed into a fine powder in big jaw crushers and ball mills and this process is called pulverisation.

 The process used for the extraction of metals in their pure form from their ores is called metallurgy 

 Ores are crushed into a fine powder in big jaw crusher and ball mills and this process is called pulverisation

 The first step of metallurgy is concentration of ore.it is done by gravity separation,froth and magnetic separation

 After the ore is concentrated,it is reduced to metallic oxide by the process of roasting and Calcination

 Roasting is the process of heating the concentrated ore 

 to high temperature in presence of excess air.

 Calcination is the process of heating the concentrated ore in absence of air at a temperature not sufficient to melt the ore.