Boateng, along with Milan midfielder Sulley Muntari, was slapped with an indefinite suspension prior to Ghana's final group game at the World Cup in June.
Muntari's ban was dished out for "an unprovoked physical attack" on an executive committee member of the GFA, Mr. Moses Armah, in a meeting.
Meanwhile, Boateng's sanction came on the recommendation of Appiah, who has now spoken out against the attacking midfielder.
"Kevin Boateng, on several occasions, was using foul words such as the 'F word' in training and most of the time I kept quiet and pretended I hadn't noticed," Appiah said.
"My Lord, he directed it to me on two occasions and he did the same with some of my technical team members.
"He did it in front of all the players and I kept quiet over it because that was a day before the game against Germany. After the Germany game, he did the same thing after which I expelled him from the training pitch.
"My intention was to let him know that it is not acceptable to use such words in front of everyone.
"For me if it was between just the two of us, I would have ignored it but repeatedly doing the same things in front of the young ones was something we could not tolerate."
