Solution:

• In smelting , the concentrated oxide ores like haematite , tin stone even after concentration , is heated with flux to remove the acidic or basic impurities forming the slag.
• An example is the reduction of iron ore (iron oxide) by coke in a blast furnace to produce pig iron.
• Froth Flotation method is mainly used to remove gangue from sulphide ores.
• Washing in a current of water is a gravity concentration method in which lighter particles are carried away by the current and heavier (ore) particles are collected at the bottom.