Which of the following processes does not involve heating?

• Calcination is defined as 'Heating to high temperatures in air or oxygen 
• Smelting makes use of heat and a chemical reducing agent to decompose the ore
• When Roasting extremely hot air is used to treat the ore or ore concentrate.
• The technique of levigation involves wet grinding of an insoluble substance into a fine powder. Depending on how much water is used, the material is added to the mill together with water, keeping the powdered material suspended, and flows out of the mill as a turbid liquid or thin paste.

Since Levigation does not involve heating.