Question

What is the the name of the process to separate sand and salt?

Answer 1

The salt and sand are actually separated by the process of solution. the salt dissolves and the sand does not. You can pour off the salt water by a process of decanting. The water will evaporate on its own. 

With sand and clay, they are both insoluble, clay particles are much smaller, but not small enough . to go through a filter. Here again decanting could be used. after swirling the flask with the sand, clay and water, pour off the cloudy water containing the clay. the sand will stay on the bottom.