To separate the mixture of sand, oil and water, which methods we will use?

Distillation is a process by which water is removed as vapours by boiling, and then the vapours are condensed to give back the water.

This will help to separate oil and water because the boiling point of water is very less than oil. Thus it can boil off faster than oil from the mixture of water and oil, and sand will remain in the container behind.