Company spokeswoman Samantha Davison told ILN it had made the changes to the facilities near Madison, Boone County, on Friday.
Meetings will be held with workers the week of June 10 to review plans for pay and benefits.
“Shutting down a mine and sending good people home is the last thing we want to do but we had to make that move in an effort to continue to adapt to the challenging conditions in the coal market,” she said.
“Demand and pricing for the type of coal mined at the Justice No 1 mine is very weak.”
Davison said there would be opportunities for some of the impacted employees within the Alpha organization and about 60 people would stay on for about six more months to finish work related to the mine idling.
“As we have done in the past, we will treat everyone fairly,” she said, noting that even with the closure Alpha still had more than 50 active operations in more than a dozen West Virginia counties.
Alpha acquired the Justice No 1 mine when it took over the Massey Energy portfolio in June 2011.
The mine is operated by subsidiary Independence Coal.
According to federal data, the Justice operation produced about 750,000 tons of coal in 2012.
