How do you separate zinc phosphate and SiO2 also known as sand?

Answer 1

Neither compound is soluble in water, however zinc phosphate will dissolve in acids while silicon dioxide will not, except for hydrofluoric acid. The reaction of zinc phosphate and the common acid hydrochloric acid is:
Zn3(PO4)2 + 6 HCl -----> 3 Zn+2 (aq) + 6 Cl- (aq) + 2 H3PO4 (aq).

All of the products from the reaction of zinc phosphate with hydrochloric acid are soluble in water. Therefore, the mixture of zinc phosphate and SiO2 only needs to be mixed with hydrochloric acid, stirred for 5 or 10 minutes and the liquid decanted off. To purify the remaining SiO2, it needs to be washed 3 to 5 times with pure water.

Answer 2

One way to separate zinc phosphate and SiO2 (sand) is by using a process called froth flotation. This process involves adding a reagent that selectively attaches to one of the substances, allowing it to float while the other sinks. The substances can then be physically separated.