Perhaps the salt crystals are still in the solution, but "suspension" is then moved quickly enough so that the majority of the dissolving process takes place in

Perhaps the salt crystals are still in the solution, but "suspension" is then moved quickly enough so that the majority of the dissolving process takes place in the area where we want the cooling to happen? EDIT: the picture makes it look like they create two solutions: one with concentrated salt, and one with water ice sludge. Those are transported separately and then mixed in the cooling tank