Greenland Resources Inc is taking a different tack to mine haulage at its Malmbjerg molybdenum project in Greenland, laying out plans in a feasibility study to use a Doppelmayr RopeCon® aerial conveyor to transport ore to the concentrator.
In a definitive feasibility study that outlined a 20-year open pit mine life with annual life of mine production of 24.1 MIb of molybdenum, Dr Ruben Shiffman, Executive Chairman, said the company had chosen to “prioritise the environment over capital expenditure”.
In addition to the planned use of a Doppelmayr rope conveyor over cheaper and less environmentally friendly diesel haul trucks – which would save the company over $80 million in capital expenditure, according to Shiffman – the company also planned to use salt water as process water in its process plant, with very low reagent concentrations to mitigate any potential environmental contamination.
The Malmbjerg project comprises of a conventional open-pit mine producing 35,000 t/d of molybdenum-rich ore for processing in a conventional base metal sulphide concentrator. The mine plan equipment fleet consists of two 34 cu.m hydraulic shovels loading 13 x 230 t haul trucks operating on 12 m benches.
The operational mining plan will utilise an economic grade control system where higher value ore will be separated and transported to the concentrator while the lower value ore will be stockpiled and processed at the end of conventional mining.
Waste rock will be stored on the west side of the deposit and used for haul road and construction activities at the mine site.
Current mining reserves dictate a mine life of 20 years where the concentrator will be fed directly from the open pit for a period of 11 years and stockpiled ore will be processed for the remaining nine years.
Ore produced from the open pit will be transported to the primary crusher and loaded onto the Doppelmayr Seilbahnen GmbH ropeway aerial conveyor for transportation to the concentrator located 21.7 km northeast of the open pit on tidewater.
“The ropeway aerial conveyor is similar to historic ore tramline systems that are employed in challenging topography where ore surface transportation systems are not topographically and economically favourable,” Greenland Resources said. “The ropeway is expected to generate electrical power for the mine site during the life of the operation.”
The ropeway aerial conveyor discharges ore into a 35,000 t “live” stockpile at the concentrator for processing. The concentrator is of a modular design constructed on barges and transported from an overseas shipyard to the project site where the barges will be permanently located in a dedicated beach location. The 35,000 t/d concentrator modular design was selected based on the economics of offsite construction and reduced concentrate production commission time.
The life of mine average mill feed grade is 0.176% MoS2 at an estimated recovery of 84.6% MoS2.
The concentrator comprises two SAG circuits feeding a conventional multi-stage flotation circuit to produce a molybdenite-rich concentrate. Due to the four-to-six-month ice-free shipping season, concentrate will be inventoried in containers on site during the non-shipping period and shipped to end users when the shipping season commences.
The estimated initial capital for the project is $820 million with $194.4 million of this being set aside for the rope conveyor.