how can you separate sand and finely ground polystyrene foam?

Answer 1

(1) I like the flotation idea. This method is also used in wastewater treatment where alum is added to municipal waste and the wastes clumps together and floats to the top.

(2) Polystyrene also dissolves in acetone (nail polish remover). In chemistry, this is call extraction -- dissolving one material but not the other. This method is used in medicine, mining, and even in making coffee.

(3) You could also burn the polystyrene off. This method is also used in analytical chemistry and in ore purification (as in smelting of iron ore).

(4) Blow off the polystyrene like how farmers used to toss rubbed grain into the wind so that the chaff would be separated from the kernels. Not a chemical process but it works.

Answer 2

Styrene dissolves quickly in many different hydrocarbon solvents such as benzene, xylene, toluene, etc. A polystyrene ("styrofoam") coffee cup dropped into one of these solvents will disappear in about 5 seconds. (I used to do this as a classroom demonstration). Then just pour off the solution and evaporate the solvent to reclaim the styrene. It won't be in "foam" form anymore. It will just be a hard, solid mass. The foam is the result of bubbling fine air bubbles through the styrene during manufacture.

Answer 3

Polystyrene in my experience has always been a substance that is extremely vulnerable to a static charge.

If you are attempting to seperate sand and polystyrene some sort of static charge may be your answer. Using an object that generates or holds a static charge may very well be your solution.

Answer 4

water would be a good idea. the sand will sink n the foam will float

Answer 5

water

sand sinks
foam floats

Answer 6

tweezers

I defer to JC.