For structural materials , such as sand and gravel, once the material is mined, washing and separating is all that is required for a useable product.
Mineral extraction is much more complex and expensive.
After the mineral and rock is mined from the ground, the ore begins processing in a mill. The ore rock is first crushed and ground up, then minerals physically separated by processes such as leaching, solvent extraction, or milling and flotation. Gold is often processed by heap leaching or bioleaching. The gold is recovered from the cyanide solution by an electrical process and refined into pure bullion. Solvent extraction-electrowinning is a process used in copper production, whereby electricity is used to extract the metal from a solvent solution.