Stillwater Mining Co (SMC) has tentatively placed an order for a third Kiruna K635ED electric hauler to meet increased production as the company initiates its next development phase – extending its underground electric truck ramp haulage system from 1,067 m above sea level (asl) down to 762 m (asl) – its next development phase to extract ore at lower levels. SMC took delivery of the first two units early last year when it opted for a dedicated ramp below the mine’s shaft bottom (International Mining, September 2011, pp8-18).

In four development phases over the next five years Stillwater plans to deepen its electric truck haulage operation by a further 457 m taking it to an elevation of 609 m (asl). In addition to the two 35 t capacity Kiruna trucks already deleivered, ABB also supplied plans and specifications for 1,707 m of overhead trolley line in phase 1, which will increase to approximately 3,660 m over phases 1-4 by 2015. SMC undertook a feasibility study into all of its options in deepening the mine which included: extending the existing shaft using conveyors, expanding its current fleet of diesel trucks as well as the electric ‘trolley’ trucks. The electric trucks were chosen and the reasons are fully explained in the International Mining magazine article.