I'm sure a process could be created that is cumbersome and or long enough to make the manufacture of Course Salt sufficiently hard.
But what we really need is a new 'fine salt' item which is granular like flour, you can grind course salt into fine and get say 10.0 units of fine salt. The fine salt is used for cooking and curing meats and other such craftable things without having to be concerned with the possible cash-cow of excessive Soap production. And a mechanism for making fine-salt from seawater (or even mining it) doesn't need to be excessively tedious.