Through its subsidiary Bear Mountain Mining Corporation, Aureus Mining operates Liberia’s first commercial gold mine, the New Liberty mine. The mine is situated approximately 100km north-west of Monrovia.
The environmental permit for the mine was received in October 2012 and the definitive feasibility study was completed in 2013. Construction work started in December 2012 and the first gold was poured in October 2013, while commercial production began in March 2016.
The annual gold production from the mine is expected to be 119,000oz for the first six years and 859,000oz over the mine life of eight years.
The New Liberty gold mine produced 17,172oz of gold in 2015.
Geology and mineralisation of Liberia’s first commercial gold mine
New Liberty is a part of the Bea-MDA property, in the Grand Cape Mount County of Republic of Liberia. The Bea Mountain mining licence is spread over 457km² and also includes the Ndablama, Gondoja and Weaju gold deposits.
New Liberty is a high-grade, archaean, shear-hosted gold deposit with pre-defined alteration and sulphide mineralogy. The mine geology is dominated by magnetite rich meta-ultramafics along with some portions of phlogopite.
The gold mineralisation is structurally controlled and hosted in a 100m-wide, steeply dipping ultramafic unit surrounded by migmatitic gneisses and amphibolites. The mineralised zones stretch to a length of approximately 2km, are between 10m-wide and 20m-wide and comprise ultramafic units filled with pyrrhotite and arsenopyrite.
New Liberty gold mine reserves
The New Liberty mine is estimated to contain reserves of approximately 924,000oz of gold grading 3.4g/t.
The measured and indicated resources are estimated to be 1.143 million ounces (moz) of gold grading 3.63g/t, whereas the inferred resources are 593,000oz grading 3.2g/t.
Mining and processing at the Liberian gold mine
Conventional open pit mining using drill-and-blast, load and haul is applied at the gold mine. The ore is loaded onto trucks using hydraulic excavators. Waste rock is dumped to the dump wrapping around the open pit.
The ore is processed using two-stage crushing circuit and a primary mill with regrinding. The ball mill has a processing capacity of 1.1 million tonnes of ore per annum.
Gold is leached in the carbon-in-leach circuit (CIL) and recovered via electro-winning. The gravity concentrate is leached in an intensive leach reactor. Cyanide in the tailings is detoxified in three stages before discharging to the tailings storage facility.
The first gold doré shipment from the mine was transported from the New Liberty Mine to MKS PAMP refinery in Switzerland in July 2015.
Infrastructure and construction details
The major works undertaken included the construction of the processing plant, tailings storage facility, ball mill and carbon-in-leach tank. The Marvoe Creek Diversion Channel was upgraded and additional housing, office space and maintenance areas were constructed.
The mine is accessible via a recently upgraded 20km laterite road with three new culvert-type bridges facilitating the transportation of equipment to the plant site.
A new township known as the New Kinjor Township is being constructed for the relocated families.
The water supply for the mine is provided from the Monrovia deep-water commercial port situated at approximately 100km from the plant site. Workers are accommodated at the Camp David accommodation complex.
Financing for the New Liberty gold project
South Africa-based Nedbank and Rand Merchant Bank provided an $88m loan facility for the Liberian mine. The financing was endorsed by the Export Credit Insurance Corporation of South Africa.
RMB Resources provided a subordinated loan of $12m for the mine development.
Contractors involved with the development of Liberia’s first commercial gold mine
Dowding, Reynard & Associates (DRA) Mineral Projects was awarded the engineering, procurement, construction and management services contract (EPCM) for the Libyan gold project. DRA was also involved in preparing the preliminary economic assessment, the feasibility study, the definitive feasibility study, and the front end engineering design work. AMC Consultants assisted Aureus in conducting the definitive feasibility study.
NCP International was awarded the contract to supply the ball mill. International Construction and Engineering was awarded the civil and earthworks contract.