Hecla Mining reported on January 11 that the U.S. Mine Safety and Health Administration had ordered the Silver Shaft at Hecla’s Lucky Friday mine in the Coeur d’Alene district of northern Idaho closed for removal of built-up material in the shaft.
The order grew out of an investigation that followed a December14, 2011, rock burst at the mine. Hecla anticipates that compliance with the order will take through year-end 2012 and has reduced its estimated 2012 company-wide silver production from 9.5 million oz to 7 million oz.
Production at Lucky Friday is expected to resume in early 2013. Apart from Lucky Friday, Hecla’s only other producing mine is its Greens Creek underground mine on Admiralty Island in southeast Alaska.
The Lucky Friday Silver Shaft is a 1-mile-deep shaft from surface and is the primary access to the mine. The sand and concrete material to be removed from the shaft has built up over a number of years and is expected to be removed primarily by power washing. All other significant activities at the mine, including construction of the mine’s No. 4 Shaft and a bypass around the December 14 rock burst, are on hold. Care and maintenance of the underground will be focused on the 4900 level, where the No. 4 Shaft infrastructure is located. The No. 4 Shaft is an internal shaft that is planned to descend from 4,900 ft below surface to an ultimate depth of 8,800 ft.