The Mining Process

Wise management of mining economies and production techniques allow us to competitively produce copper and molybdenum concentrates for a world market.

The path for metal concentrates from earth to railcar involves many separate processes, mechanical and chemical, overseen by trained personnel. Our attention throughout to maintaining equipment in good operating condition and our willingness to strategically invest in new, more efficient machinery are key. Responsibility to the safety of our employees and to Montana’s environment is in every aspect of our mining process.

The Mining Process

  1. 1. Rotary drills bore 48 foot holes, 9-7/8 inches in diameter into the granite host rock.
  2. 2. Drill cuttings are assayed to verify composition.
  3. 3. Drill holes are loaded with explosive to blast and fracture the rock.
  4. 4. Massive electric shovels load loose ore or waste into haul trucks.
  5. 5. Ore is hauled to the crusher in 240 ton capacity trucks. Waste goes to a designated waste rock repository.
  6. 6. The primary crusher reduces large chunks of raw ore to dimensions under six inches. The secondary crushers then reduce the size of the rock further to three-quarters of an inch.
  7. 7. The crushed ore is then routed through rod mills and ball mills where it is pulverized to a fine powder. Water is added to the process which makes the pulverized rock slurry.
  8. 8. The slurry is then pumped into the flotation cells in the concentrator where lime and other chemicals are added to liberate the metal sulfides. Molybdenum and copper is extracted, separated and dried for shipping.
  9. 9. Resulting high-grade molybdenum concentrate is bagged and transported to roasting facilities in the US. Copper concentrate is loaded into 100 ton rail cars and shipped to smelters in North America and overseas.
  10. 10. Water used in the process is recycled back into the mill circuit and disturbed land undergoes reclamation and revegetation.

Montana Resources also produces precipitated copper by cycling water from the Berkeley Pit through scrap steel cans. Through ion exchange, copper trades places with the iron in the steel can.  The copper then drops out as a sludge. This sludge is referred to “cement copper concentrate” and consists of approximately 70% copper metal.