It was the rarest of news in the coal mining hollows of Appalachia: A once powerful executive, Donald Blankenship, was sentenced Wednesday to a year in prison for conspiring to violate federal mine safety laws at the Upper Big Branch mine in West Virginia, where 29 workers died in an explosion six years ago. The very idea that a dominant baron of the industry called King Coal could be brought to justice and put behind bars shook the region, where miners have long complained that they face dangerous and illegal working conditions that routinely result in no punishment.

Mr. Blankenship, who served as chief executive of the Massey Energy Company, was not accused of causing the explosion, but his management methods, so notoriously focused on profitability, came under investigation after the disaster and led to his federal conviction on a misdemeanor charge in December in a Charleston courthouse. While Mr. Blankenship sought probation and maintained his innocence at sentencing, Judge Irene Berger delivered the maximum one-year sentence, citing “your part in a dangerous conspiracy” aimed at “putting profitability of the company ahead of the safety of your employees.”

The mine disaster, America’s worst in modern times, was traced to flammable coal dust and gas that accumulated despite workers’ complaints to management. The mine’s history of thousands of violations was laid bare by investigators, with Mr. Blankenship maintaining that health and safety were uppermost concerns at the mine. Autopsies on the 29 victims told a different story of a hard work routine, with 71 percent showing signs of the incurable coal dust affliction called black lung — far above the industry average of 3.2 percent.