COEUR d'ALENE - An official for the federal Mine Safety and Health Administration said conditions within the Lucky Friday silver mine's main shaft have parallels to problems at a Nevada gold mine where a 2010 shaft accident claimed the lives of two workers.

"We're not in the business of putting miners out of work; we're in the business of making sure that the conditions they work in are safe," said Joseph Main, assistant secretary of labor for mine safety and health.

MSHA earlier this week ordered that the walls of the mile-deep shaft that is the main entrance to the mine be scrubbed to remove sand and concrete material that can break off and endanger miners.

Hecla Mining Co., which operates the mine, estimated it will take about a year to complete that job, throwing hundreds out of work.

Phil Baker, Hecla's chief executive officer, said Wednesday that company officials believe the shaft is safe.

However, federal inspectors found loose rock in Lucky Friday's primary shaft and several leaks in a pipe that transports sand and cement into the mine, said Neal Merrifield, MSHA's administrator for metal and non-metal safety. The pipe travels along the wall of the shaft.

"Our concern is that we really don't have a good idea about the total condition of that pipe," he said.

If the pipe were to burst, or if concrete deposits from the leaks were to tear loose from the shaft's walls, workers traveling in the shaft could be killed, Merrifield said.

"You can imagine what would happen if one of these rocks would fall 6,000 feet and hit somebody or strike the cage," Merrifield said.

The situation with Lucky Friday's primary shaft is similar to the 2010 accident at Barrick Gold's Meikle Mine in Nevada, he said.

In that accident, two workers were trying to unplug a pipe in the mine shaft. The 24-inch pipe burst and the falling pipe and other debris struck and killed the workers, the accident report said.

The Dec. 20 inspection that found problems with Lucky Friday's primary shaft was a "special emphasis" inspection developed by MSHA after the Upper Big Branch Mine explosion, which killed 29 coal miners in West Virginia in 2010. Mines with recent accidents and fatalities get additional attention from inspectors.

Lucky Friday fits that category because two workers died in separate accidents last year, and seven others were injured after a rock burst in December, Main said.

The closure means 185 of Hecla's workers at Lucky Friday have been laid off, along with up to 100 workers employed by contractors who work at the mine. Miners average $100,000 a year in pay and benefits, pay that is nearly impossible to replace in this area.

The closure could reduce income in the Silver Valley by more than $13 million if it lasts for a year, the Idaho Department of Labor said Friday.