PolyMet Mining reported in early February 2011 it simplified the proposed metallurgical process at its NorthMet copper-nickel-precious metals project located in the Mesabi mining district in northeastern Minnesota. The company now plans to build the project in two phases. Phase I calls for production and marketing of concentrates containing copper, nickel, cobalt and precious metals. Phase II will process the nickel concentrate through a single autoclave, resulting in production and sale of high-grade copper concentrate, value-added nickel-cobalt hydroxide, and precious metals precipitate products.
Previous plans included a second autoclave and a copper solvent extraction/electro-wining (SX-EW) circuit to produce copper metal along with value-added nickel-cobalt hydroxide and precious metals precipitate products. The changes reflect continued metallurgical process and other project improvements as well as improved environmental controls that are being incorporated into the project’s Supplemental Draft Environmental Impact Statement, which is scheduled for completion this summer. The advantages, compared with the earlier plan, include a better return on capital investment, reduced financial risk, lower energy consumption, and reduced waste disposal and emissions at site, the PolyMet statement said.
PolyMet’s last formal update of NorthMet project scope and costs was in May 2008, when total project costs for the two-autoclave plus SX-EW circuit were estimated to be $602 million. Of that total, approximately $127 million was attributed to the second autoclave and the copper circuit.
PolyMet plans to provide a detailed project update when the project development plans now being analyzed in the SDEIS are finalized. This update will include revised mine plans and process and project improvements.
PolyMet controls 100% of the NorthMet copper-nickel-precious metals orebody through a long-term lease and owns 100% of the Erie plant, a large processing facility previously used to process taconite iron ore. The company has completed a definitive feasibility study for the project and currently is seeking environmental and operating permits to enable it to begin production.