Idaho Cobalt Mine, USA

The Idaho primary cobalt mine development project is owned by Canada-based Formation Metals. The project will develop, operate and reclaim the Idaho cobalt mine, an undeveloped site situated in east-central Idaho, US. The mine will be developed into an 800t/d operation. Construction will begin in the first quarter of 2010.

The mine will begin production in early 2011. When operational, the mine will annually produce 1,525t of high purity and super-alloy-grade cobalt. Production will equal 3.3% of global cobalt supply.

Mine development

A three-phased mine development programme will oversee the construction of the processing and ancillary facilities. Phase I will take place between January and March 2010 and will include timber clearing works for the soil stock pile area, new and existing roads around the mine site, concentrator pads and a tailings aond waste rock storage facility (TWSF).

In the second phase the mine will be developed to produce 400t/d. Scheduled for the second quarter of 2010, this phase will include construction of the mill and ancillary facilities. The ram mine portal, tram, mill, water management pond, roads, borrow areas and a soil stockpile area will also be constructed.

Mill and ancillary facilities will be built on Big Flat, an area between Big Deer Creek and Little Deer Creek. The mill will comprise a hard ore storage area, a fine ore conveyor, a ball mill grinding circuit, flotation cells, an analytical laboratory, pipelines, dewatering equipment, a water treatment facility and a shipping dock. Ancillary facilities will include power cables, fuel storage tanks, water drainages, warehouse and maintenance plants, administration offices, change house and domestic water disposal.

Development of the mine at depths below the water table will be carried out in the third phase between October and December 2010.

Geology

The project area lies within the Idaho cobalt belt that is hosted within the Proterozoic Yellowjacket Formation. The belt is a strata-bound copper and cobalt complex.

Reserves

The project consists of 2.636mt of diluted, proven and probable reserves. Reserves are graded at 0.559% cobalt, 0.596% copper and 0.014%oz per ton gold. The assumed cut off grade stands at 0.2% cobalt. In addition, inferred resources are estimated at 1.122mt graded at 0.585% cobalt, 0.794% copper and 0.017oz per ton gold. This includes contained metals equivalent to 42.6 million pounds of cobalt, 49.1 million pounds of copper and 56,000oz of gold.

Production

At full capacity, the project will produce 800t/d. Annual processing capacity will be 280,000t of cobalt-copper-gold bearing ore. An estimated 2.9 million pounds of cobalt, 2.6 million pounds of copper and 3400oz of gold will be produced annually over the life of the mine.

Mining

Ore will be mined using underground mining methods. Two ventilation shafts will be installed in the process. Post extraction, ore will be conveyed to the mill located at Big Flat.

An overhead tram will stockpile the ram ore and waste rock at 1,000ft height from the portal to the mill. At peak capacity, nearly 32t of dry concentrate and 768t of dry tailings will be processed at the mill per day. The concentrate will be hauled to a processing facility, located off site.

Environmental impact

The mine will be operated with minimal environmental impact. Low impact methods including careful disposal of waste rock and tailings will be adopted to protect water quality. The TWSF and water management pond was designed using data from a geochemical testing programme that was conducted by Formation Metals to describe waste rock and tailings characteristics. The TWSF will be equipped with a composite underliner built above a prepared subgrade. It will consist of a low permeability soil layer below a synthetic liner.

Water infiltrating the tailings and waste rock will be collected in a drainage collection system built above this liner. An adjacent area within the plant will collect the waste rock and tailings. Half of the tailings will be used as backfill underground, while the left over will be disposed off in the TWSF through dry stacking method that avoids the need of a dam.