How is salt manufactured for the shops?

Answer 1

Salt is not manufactured; it occurs naturally. There are two common processes of recovery.

In sunny countries with a sea coast, seawater is allowed to fill a large basin. The sun's rays evaporate the water leaving salt behind. The basin is repeatedly refilled until almost full of salt which, when dry, can be shipped away.

Where a salt deposit lies underground, two wells are bored. Very hot water is pumped down one. A saturated solution of brine is then pumped up the other. When the brine cools, much of the dissolved salt precipitates out. The cool remainder is then reheated before being pumped down again.

Answer 2

Sometimes salt can be used as extracted from the mine or from sea water; an impure salt is dissolved, filtered and refined by repeated crystallization/recrystallization processes.