Some ideas for magical uses:
Dissolve Black Salt in water and sprinkle where your enemy walks to get them out of your life.
Mix Black Salt, Red Pepper and Sulphur for a strong sprinkle around the home of those you wish to move away.
Sprinkle Black Salt around a Black candle dressed in Hot Foot oil to get rid of a bothersome person.
For in depth information on how to use this and other hoodoo herbs and roots, I recommend Hoodoo Herb and Root Magic by Catherine Yronwode which can be found in our Books section.