REFILE-UPDATE 1-Hecla says workers safe after Lucky Friday rock burst

* Says seven people treated for non-serious injuries

* Says mine closed pending investigations

* Says blast was unrelated to mining activities

DEC 15 (Reuters) - Hecla Mining Co said seven people were injured after a rock burst at its Lucky Friday silver mine in Idaho but added that all miners had been removed safely from the facility.

The mine has been closed pending further investigation of the rock burst, which the company said was not related to mining activity.

The incident occurred on Wednesday evening about 5,900 feet below the surface, Hecla said in a statement.

This is the third incident at Lucky Friday, after a ground collapse in April and another accident in November, which claimed the life of a contractor.

Shares of Hecla closed at $5.73 Wednesday on the New York Stock Exchange.