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MEI Online: Plant Operation News: North America: December 20th 2004


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:: PolyMet Mining Awards Bateman International Metals Feasibility Study

Bateman has been appointed by PolyMet Mining Corp. as its coordinating consultant for its fast-track NorthMet study in north-eastern Minnesota, USA. The US$2M study concerns the feasibility of establishing a facility to produce 33 000 t/yr of copper cathode at NorthMet, a low-grade base- and precious-metals deposit which contains valuable quantities of copper, nickel, cobalt, palladium, platinum and gold.

Bateman will take the lead in the process design, testwork and infrastructure and retain consultants for the other elements of this definitive feasibility study.

The contract will be carried out through Bateman's Brisbane, Australia, office. Work commenced on schedule in mid-July 2004, under a series of pre-contract work orders and is due to be completed by the third quarter of 2005.

Bateman was selected because of its considerable experience in feasibility studies, its expertise in mineral-processing plants for base and platinum group metals (PGM) and, in particular, its expertise in the engineering, design, and construction of pressure-leach circuits which are at the core of the proposed process route for this project. Bateman applied this technology in such recent projects as Gunpowder Copper in Australia and Sepon in Laos.

Bateman will provide the design- and cost-estimation services for the metallurgical plant. As currently envisaged, the project will process 25 000 t/day of ore from the NorthMet deposit to produce, annually, 33 700 t of copper cathode, a nickel / cobalt hydroxide containing 7 800 t metal and a PGM concentrate containing 120 000 oz (including gold).

The process route is defined by the PlatSolTM process and all other unit operations are standard, subject to further pilot testing. The re-utilisation of the large 100 000 t/day mothballed mill / concentrator at the Cliffs-Erie facilities means that most of the key infrastructure is already in place. The project, as it is currently envisaged, requires the development of a mine at the NorthMet deposit. Ore will be truck hauled from the pit to a rail transfer facility for rail haulage to the primary crusher located at the Cliffs-Erie process plant approximately 10 km (6 miles) away.

Ore from the mine will be processed through the existing Cliffs-Erie crushing / milling plant. New flotation circuits will be added and a new hydrometallurgical plant constructed. This facility will produce saleable products of copper cathode, a nickel / cobalt hydroxide and a PGM concentrate. Waste streams resulting from the various processes will be contained in established tailings impoundments. The construction of the envisaged process plant will involve the following main activities / facilities.

Construction of a new flotation and regrind facility in the existing concentrator building. The regrind mills exist but all other concentration equipment will be new with associated civil and structural work, piping, electrical distribution and instrumentation / control.

The pressure-leaching circuit will be of an entirely new construction in a purpose designed building and will comprise two 4,1 m x 24,6 m autoclaves and associated equipment including concentrate thickening and storage.

Downstream from the pressure-leaching circuit are the unit operations for solid / liquid separation and disposal of the leach residue to lined cells in the existing tailings impoundment, PGM recovery as a precipitate, neutralisation of the pregnant leach solution, copper solvent extraction and electrowinning (126 cells of 54 cathodes each) and the precipitation of a nickel / cobalt hydroxide.

Waste streams will be pumped to new tailings impoundments constructed on the existing tailings dam. Infrastructure and ancillary services will all be provided based on the re-utilisation of existing facilities where possible. These will be refurbished and upgraded to meet the new plant requirements and, where required, new facilities will be constructed.

PolyMet Mining Corp. is an investor-owned junior mining company whose principal asset is the NorthMet deposit, one of the world's largest undeveloped low-grade base and PGM resources.




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