Concentration of ores: Removal of impurities, such as soil, sand, stone, silicates, etc. from mined ore is known as Concentration of Ores.Ores which are mined often contain many impurities. These impurities are called gangue. First of all, concentration is done to remove impurities from ores. Concentration of ores is also known as enrichment of ores. Process of concentration depends upon physical and chemical properties of ores. Gravity separation, electromagnetic separation, froth flotation process, etc. are some examples of the processes which are applied for concentration of ores.Conversion of metals ores into oxides:It is easy to obtain metals from their oxides. So, ores found in the form of sulphide and carbonates are first converted to their oxides by the process of roasting and calcination. Oxides of metals so obtained are converted into metals by the process of reduction.Roasting: Heating of sulphide ores in the presence of excess air to convert them into oxides is known as ROASTING.Calcination: Heating of carbonate ores in the limited supply of air to convert them into oxides is known as CALCINATION.Reduction: Heating of oxides of metals to turn them into metal is known as REDUCTION.Purification: Metal; so obtained is refined using various methods.