If we can boil sea water to get salt then why mine for it?

Boiling sea water won't give you salt in commercial or appreciable quantities. You can't get salt in commercial quantities by simply boiling sea water. You need a more sophisaticated process- DESALINATION. There are 35 grams of salt dissolved in 1 kilogram of typical seawater. read more

Others boil saltwater with the intention of removing the salt to make safe drinking water. The BBC reported that this is accomplished through distillation. The process involves boiling water and then cooling water vapor in order to condense it into pure, salt-free water. read more