The Boliden Area operation is comprised of several mines, with ore processed at the Boliden Mill. Thirty-one mines have been developed throughout the life of the operation so far and the mill also receives slag from Boliden's smelters. Mines currently in operation include underground mines: Kristineberg, Renstrom and Kankberg with additional ore feed from the Maurliden open pit. Ore from the Maurliden pit tends to be used to supplement the higher grade underground ore feed to the mill. Kankerg is a gold-silver-tellurium deposit, extracting tellurium from the ore using a proprietary hot-leach process.