Question

How to separate this mixture physically?

I have a mechanical mixture containing very small pebbles, pencil shavings, black sand, and a white powder (most likely flour or chalk). What is the process of physical separations that I need to use?

Answer 1

Basically it is separating by density and volume.

Explanation:

It depends in part on whether the white powder is soluble/miscible in water or not. I am assuming that it is for this answer. Alternatively it could be separated from the pencil shavings in a separate step.

1. Put everything into a vessel filled with water.
2. The white powder will dissolve into the water (or be entrained) and the pencil shavings will float.
3. Skim off the pencil shavings and decant the water. It may be boiled off recovery of the white powder is desired.
4. Use an appropriately-sized sieve to separate the sand from the pebbles.