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The lead and zinc flotation circuits at Red Dog Mine are preceded by a preflotation circuit which recovers naturally-floating organic carbon contained in the ore. Organic carbon is a potential contaminant in the lead concentrate and is detri-mental to lead-zinc selectivity. Prior to 2007, the Red Dog pre-flotation circuit consisted of a single stage bank of tank cells which floated the organic carbon. The preflotation concentrate was discarded directly to tailings. However, this stream con-tained significant amounts of lead and zinc. Zinc loss to pre-flotation ranged from 2% to 6%, relative to the zinc in the mill feed and was proportional to the amount of organic carbon in the ore. The main mechanism of the zinc loss was entrainment. Pilot plant and modeling testwork were conducted to examine the use of a Jameson Cell to clean the preflota-tion concentrate. Results indicated that up to 90% of the zinc deporting to preflotation concentrate could be returned to the flotation circuit for recovery. The installation of a 5.4 m Ø Jameson Cell with 18 downcomers was initiated in June 2006. The new preflotation cleaning circuit was commissioned in March 2007. Conservatively, preflotation cleaning has resulted in zinc and lead absolute recovery gains of 1.0% and 1.5%, respectively. The $9.1M project has a payback period of approximately 1 year at current metal prices. T. Smith, Project Metallurgist, Red Dog Mine, Teck Cominco Alaska Inc., Anchorage, Alaska D. Lin, Senior Research Engineer, Teck cominco Metals Ltd., Toronto, Ontario B. Lacouture, Chief Metallurgist, Red Dog Mine, Teck Cominco Alaska Inc., Anchorage, Alaska, and G. Anderson, Manager, Mineral Processing, Xstrata Technology, Canada, Ontario
