Dolores has traditionally been an open pit silver-gold mine that uses conventional heap leaching to produce gold and silver dore. In 2015, Pan American Silver Corp. announced plans to expand the operation by adding a 5.6kt/d pulp agglomeration circuit to the process flow, improving silver and gold recoveries. In addition, a 1.5kt/d underground mine will be developed beneath the existing open pit operations. On completion, the expanded operation is expected to produce in excess of 206koz of gold and 6.3Moz of silver at peak production. Expansionary capital cost of the agglomeration facilities and the underground mine was estimated at US$112 million.