Stillwater Advancing Montana Development Projects

Stillwater Mining reports progress on its $180-million Blitz and $8-million Graham Creek underground mine development projects on the J-M Reef near its existing underground platinum
group metals mines in south-central Montana. (Illustration courtesy Stillwater Mining Co.)

Stillwater Mining reported in early October 2012 that it is making progress on the Blitz and Graham Creek under-ground mine development projects on the J-M Reef near its existing underground platinum group metals (PGM) mines in south-central Montana. The Blitz project is located east of the Stillwater mine, and the Graham Creek project is located west of the Boulder Creek mine.

At the Blitz project, a recently acquired tunnel-boring machine (TBM) is in place and operational. The project will be in development for about five more years and involves three interdependent initiatives: a TBM drive extending about 23,000 ft (7,000 m) to the east from the existing Stillwater mine infrastructure; a second underground drift to be conven-tionally driven parallel to and about 600 ft (183 m) above the TBM drive; and a new surface portal and decline to be located about 4 miles east of existing Stillwater Mine facilities. The new surface portal will be conventionally driven from surface and ultimately will intercept the two primary Blitz tunnels, providing ventilation and emergency egress for the Blitz area.

The TBM drive, parallel drift, and sur-face portal and decline are designed to provide the backbone for future mining in the Blitz project area and will cost an estimated $180 million, of which approximately $33.4 million had been spent through September 2012. The Blitz project is intended to strengthen Stillwater Mining’s ore reserve position by establishing access to previously un-developed portions of the J-M Reef, with the potential for expanding mine produc-tion rates in the future. Ore produced from the Blitz project would be processed at the Stillwater mine mill, which has excess permitted capacity.

The Blitz project remains on track for completion in 2017.

At the Graham Creek project, Stillwater Mining is using one of the original East Boulder Mine TBMs to develop 8,200 ft to the west of the existing East Boulder in-frastructure. Total Graham Creek TBM development footage through September 2012 was about 5,700 ft (1,740 m). The TBM development is scheduled to wrap up late in the first quarter of 2013, after which two new vertical ventilation raises to surface will be added.

Total cost of Graham Creek develop-ment work is projected at around $8 mil-lion, of which about $4 million had been spent through September. In view of the technical complexity of the ventilation raises, the company anticipates it may need to bring in an outside contractor to develop the raises, which could increase the total estimated cost of the Graham Creek project by about $3 million.

Stillwater Mining could realize some early Graham Creek PGM production dur-ing 2014, although full development, including all definitional drilling, is target-ed for completion in early 2015. The com-pany does not yet know if the project will facilitate any increase in production rates at East Boulder, which like the Stillwater mine has excess permitted mill capacity.

In other developmental news, at Stillwater Mining’s processing operations in Columbus, Montana, the company is nearing completion of a project to con-nect an older, previously idled smelting furnace to its current primary furnace, which was commissioned in 2009. The idled furnace has been reconfigured as to serve as a slag-cleaning furnace, support-ing improved metal recoveries and addi-tional recycling growth, as well as provid-ing backup smelting capacity. The newly structured slag cleaning operation will be functional at the beginning of December 2012, and both furnaces should be oper-ating in tandem by the end of the year to increase PGM recoveries.

Stillwater Mining anticipates the slag cleaning operation will yield more than 2,500 oz/y of PGMs from both mined and recycled materials that would otherwise remain bound up in smelter slags.

At the Marathon PGM-copper project in Ontario, Canada, owned 75% by Stillwater Mining and 25% by Mitsubishi, a definitive engineering study is currently being conducted by Nordmin Engineering Ltd. The study will yield a final project design and firm cost estimates, as well as information required to obtain the final Marathon operating permits.

An environmental impact statement for the Marathon project, submitted in July 2012, is currently under public review and open to public comment, with hearings by a joint federal-provin-cial environmental review panel expect-ed to begin sometime in the second quarter of 2013.

As featured in Womp 2012 Vol 11 -