Iron Purification at Teck Cominco's Trail Operations

Teck Cominco Metals Ltd. operates an integrated zinc-lead smelter at Trail, British Columbia, Canada. The zinc circuit comprises three parallel operations: conventional fluid-bed roasting, direct zinc pressure leaching of concentrates and atmospheric leaching of zinc oxide fume recycled from the lead smelter. The products from these three areas are combined in the main leaching plant where they undergo iron purification. Unlike most leaching circuits, the leach process in Trail begins with an acid leach and is followed by a neutral leach. An evaluation was undertaken to determine if the process at Trail could be improved by converting to the conventional neutral leaching process with a subsequent acid leach of the residues. This paper explores the results of these tests and the implications for Trail Operations.