The move comes after citing weakening demand from Alpha’s electric utility customers.
The mining company said it will plans to idle two more by early 2013.
Alpha’s other mines will alter work schedules to reduce output, cutting overall production by four million tons a year.
Alpha Natural Resources chief executive Kevin Crutchfield said the move has been taken after adverse market conditions left us no choice.
"In the days ahead, we will be examining all aspects of costs across our entire value chain, including cost reduction reviews with all key stakeholders," said Crutchfield.
Stricter emissions standards have prompted utilities to shut down coal-fired power plants rather than retrofitting them.
