A proposed mine just across the border from Juneau could use barges for the transport of equipment, supplies and mineral concentrate, eliminating the need for a new 100-mile road to Atlin. Vancouver-based Redfern Resources’ surprising plans for Tulsequah Chief were published at the end of January in a feasibility study by Wardrop Engineering. In May 2005 Redfern had put the project on hold because of economic concerns, and in August 2006 environmental groups filed a lawsuit in Canada opposing the road.
The Tulsequah Chief property in British Columbia was first mined by Cominco in 1951-57. It contains a probable reserve of 5,378,788 metric tons grading 1.40 percent copper, 1.20 percent lead, 6.33 percent zinc, 2.59 grams per tonne gold and 93.69 grams per tonne silver, according to the feasibility study. Redfern would mine at a rate of 2,000 tons per day for an estimated mine life of eight years. The capital cost of the mine would be C$201.5 million and the payback period would be 29 months. The barge transportation system represents a capital cost reduction of C$46.5 million, plus a significant operating cost reduction.
For transportation Redfern hopes to use two air cushion barges towed by an amphibious tug that would operate year-round on the Taku River. There are likely to be some potential weather delays due to high winds, the feasibility study noted. All equipment and supplies would be shipped to site via Juneau during construction and operations.
One of the air cushion barges would also be used to haul mineral concentrate produced by the mine to Juneau for trans-shipment via an existing commercial ocean barge service to Skagway, where it would be ship-loaded for transport overseas. The disused Skagway Ore Terminal is already being retrofitted to handle concentrate from Sherwood Copper’s Minto mine in the Yukon. The Taku River Tlingit and commercial fishermen from Juneau have expressed concerns about whether the air cushion barges would interfere with the river’s salmon fishery.
Air cushion barge hovers, but different than hovercraft
An air cushion barge is a barge that hovers on the water, but there are several differences between an ACB and a hovercraft, according to Redfern. Air cushion barges travel at a very slow speed and sit in the water at a depth of about 18 inches. They are quieter than hovercraft and generate minimal wake. Each of the two ACBs to be used by Tulsequah Chief would have a payload of 450 metric tons, and less than one trip per day carrying concentrate would be required. The ACBs would not be used for personnel transport: workers would be flown to site on charter planes.
“The Tulsequah mine will provide a significant economic benefit to the region and the province through job creation, workforce training, new business opportunities and taxes. Further, we believe that there is considerable opportunity to expand the reserve through additional exploration at the mine, at the Big Bull deposit, and elsewhere on the property,” said Terry Chandler, Redfern’s president and CEO.
The company believes that any necessary permitting amendments for the ACB alternative could be completed in three to six months and would not delay the project’s development schedule, which envisages production starting in late 2008. A British Columbia Project Approval Certificate was issued in December 2002 and federal environmental assessment screening approval was issued in July 2005.
The State of Alaska’s Large Mine Team in the Department of Natural Resources has said that it will review Tulsequah Chief project documentation to ensure that water treatment systems can realistically meet Canadian water quality standards at the mine site; tailings storage facilities are constructed to be geotechnically stable; groundwater water quality is protected and contingency pump-back systems are appropriately designed; and access roads are constructed and maintained in a manner that protects fish resources.
Tulsequah Chief would be an underground mine, with an existing drift to be used as the primary access route. The drift would be enlarged to accommodate modern diesel trackless equipment, according to the feasibility study. In the mill, gold concentrate will be separated using a gravity circuit and an on-site refinery will be used to produce gold bullion. Copper, lead and zinc concentrates will be produced and limestone will be added to the tailings to ensure there is no potential for acid generation. The limestone will be quarried, crushed and milled on site.
