Salts of metals and acids, or of the reagents involved.
Which metals, which acids, which chemicals were involved, what formed these salts?
What chemical changes or reactions were involved in making these salts?
What products were removed or what traces remain?
Were they recrystallized to make them purer?
Full of drag down contamination and or inclusion contaminated of insoluble or other chemical reactions?
While these salts are obviously not pure or made up of only one metal, or of one acid or one chemical reagent.
With possible metal oxides and hydroxides as well as metal particles, and other salts or combinations of other metal salts, with drag down and possible contamination of other reduced and oxidized metal contamination.
In the formation of salts, the process of crystalization will normally make the different types of metal/acid salt formation fairly pure, redissolving and recrystallization is a way to make the crystals of the salts purer with each recrystallization.
what are these salts?
Well, obviously they are products of any metal, any acid, any base or caustic, or chemical reagent used in the process that created them.
Note while many of these metals and acids or salts can be dangerous to humans, harmful to animals and the environment, they can poison killing the soil's natural ability to grow plants.
While we treat our waste in a process to remove as much of the more deadly or toxic metals (and put them into a form that is less water-soluble, and less dangerous to us or our environment, ideally making these metals less toxic metals changing them into a more stable state as metal hydroxides then into metal oxides or even into elemental metal, removing the more toxic metals from the waste as much as possible, by displacing metals from solution by dissolving a more reactive metal that is less toxic (although very possible still toxic metal but less so), and removing other metals as oxides or insoluble hydroxides as much as possible, changing the solutions into less toxic forms before proper disposal of the insoluble, again if possible making the insoluble metal hydroxides, into safer metal oxides (roasting) or into elemental metals forms were possible before disposal.
These less toxic salt solutions upon evaporation will form salts, containing any ions of the different metals, any of the acids, any of the different chemical or reagents, and any of the reactions of these that were involved in making them, although less toxic if the waste was treated properly, while safer (but not safe to eat, to put in soil or to dump down the drain or toilet), while most likely very similar to sea salt at this point it is still harmful and can still contain any metal acid or chemical that was ever involved in making these salts...
While you can probably touch the clear salt to your tongue and taste the clear salt and it may likely be a fairly pure form of sodium chloride, or some very reactive metal sulfate, you probably would not die today and you may see that it tastes just like table salt, or a combination of different metal chloride and or metal sulfate salts.
But why would anyone want to? you can determine something is acid or not by tasting it, Most chemists today have better ways of testing salts or acids than tasting them.
what are these salts?
If you only used one metal and one acid to form these salts the answer would be simple.
Add a combination of different metals and several different acids and other chemical reagents and do a slew of magic tricks with the solution the answer becomes more complicated. and
To tell what the different salt crystals are then you would need to look into testing for the different metal cations involved and tests of the different acids or basic chemical anions that are involved...
Well if you really want to know you can always test for each of the different (metal) cations and you can also test for the different Anions (acids or bases involved in these salts), although these different tests themselves can get fairly complicated as much of them seem to be processes of eliminations, making the testing a long drawn out string of many different tests, somewhat complicated processes to follow with many steps that must be done in certain orders not leaving any of the tests out of the series of tests, with many of the tests just eliminating what is not there, somewhat hard to follow chemical tests in order to get to the answers.
I would still consider these salts (or solutions) hazardous, and dispose of them properly.
Although after recrystallization of the ionic salts you probably have mostly a form of sodium chloride (table salt) with some other metals cations and nonmetal anions involved.
None of the processes we use in waste treatment can guarantee that we have the removal of (ALL) of the toxic ions of metals, or anions.
We just make it into a much safer slat or solution to dispose of, that still needs to be treated as toxic and still needs to be disposed of properly...