Reuters quoted the company as saying in an e-mail: "We are in the process of resuming coal production, as planned."
Glencore had estimated that the closure will cut its output by five million tons, 2.5% of thermal coal exports forecast by Australia.
During 2014, the thermal coal prices were hit by surplus supply and lower imports into Beijing as per the new trade targets, Australia’s Department of Industry said.
Glencore earlier said: "This is a considered management decision given the current oversupply situation and reduces the need to push incremental sales into an already weak pricing environment.
"We remain confident in demand growth for our products and believe that the supply and demand balance will be restored in the medium term."
The company has a workforce of 8,600 at its 13 mine complexes across New South Wales and Queensland.
