A former coal baron is donating $1 million to miners protesting in Kentucky after their employer went bankrupt and their paychecks bounced.

Ex-Cumberland Resources Ltd. founder Richard Gilliam said he will give $2,000 apiece to 508 workers waiting to be paid by Blackjewel LLC. Gilliam, who started a charitable foundation with his late wife in 2010 after selling Cumberland, said in an emailed statement that he hopes the money “will act as a bridge” for the miners until they’re paid.

It’s the latest in a string of breaks for the miners, who for more than a week have blocked tracks...