The Selinsing gold mine is an operating high-grade gold mine at Bukit Selinsing in Pahang State, Malaysia. Monument Mining is the owner and developer of the mine, which comprises both oxide and sulphide deposits.
The pre-feasibility study of the project was completed in 2016, while the feasibility study was completed in February 2019. The study focused on assessing the expansion of the existing oxide-based mine and extract sulphide ore.
Sulphide ore mining at Selinsing is expected to be commenced in the fourth quarter of 2019, while ore processing is scheduled to be started in the first quarter of 2020.
The transition from oxide to sulphide ore is expected to extend the mine life of Selinsing by six years. The expansion project is estimated to produce 223,000oz of gold over its six-year mine life.
Selinsing gold mine history and development
Monument Mining acquired the gold mine, which comprises four properties namely Selinsing, Buffalo Reef, Felda, and Famehub, in June 2007. Oxide ore mining at Selinsing and Buffalo Reef properties respectively started in July 2009 and November 2012.
Ore is currently processed at the 40,000tpa processing plant, which began commercial operations in September 2010. The plant’s production capacity was increased to 1Mtpa in July 2012.
Selinsing gold mine geology and mineralisation
The Selinsing gold mine is located on a lineament known as the Raub Bentong Suture in Pahang.
The Selinsing property is hosted in east-wards dipping shear zone, with the main mineralised shear hosts gold-bearing quartz veins and stockworks dipping to the south-east.
The mineralised shear zone is located within a sequence of felsic tuff, clastic argillites, and arenites along with silicified sediments. High-grade mineralisation is contained as quartz complex veins and quartz-carbonate veins in the sedimentary rocks.
Gold mineralisation at the Selinsing property is contained within pyrite and arsenopyrite, while mineralisation at the Buffalo Reef shear zone is structurally controlled and associated with Permian sediments.
Reserves
The probable ore reserves at Selinsing gold mine are estimated to be 3.92Mt grading 1.86g/t Au, while contained gold is estimated to be 234,600oz.
Mining and ore processing
Conventional open-pit mining, involving drilling and blasting, is being applied at Selinsing. The extracted oxide ore undergoes three-stage crushing followed by ball milling, gravity recovery, cyanidation, and carbon-in-leach treatment to produce gold.
The existing 3,000tpd oxide ore processing plant will be upgraded to treat sulphide ore. With a capacity of treating 955,000tpa of ore, the upgraded plant will feature a flotation plant, a bacteria bio-oxidation (BIOX) treatment facility, and ASTER process for thiocyanate and cyanide removal.
The new BIOX CIL circuit will process the refractory sulphide ore and concentrates while retrieving the gold, which cannot be recovered by conventional cyanide leaching. Final gold will be recovered from gravity concentrate leach and carbon strip solutions through the electrowinning process.
The CIL tailings will be forwarded to the activated sludge tailings effluent remediation (ASTER) unit.
Infrastructure
The Selinsing mine can be reached by sealed roads from the regional centres of Kuala Lipis and Raub.
Workers will be accommodated at a new site accommodation camp near the valley adjacent to the main office, during processing plant construction.
The nearby Sungai Kermoi River will be the main water source during sulphide ore extraction and processing.
Power supply for the mine will be provided by Tenaga Nasional Berhad from Kuala Lipis by constructing a new 33kV line, while Monument will also construct a new 33kV substation and a switch room.
A new 1.5MW diesel-fuelled generator will be used temporarily to power the project office, site accommodation, main administration building, and construction equipment.
Contractors involved
Minetech Construction was engaged as the mining contractor for the Selinsing gold mine.
Snowden prepared the pre-feasibility study of the project, while Practical Mining conducted a study for the extraction of sulphides.
SRK Consulting conducted the scoping study of the expanded tailings storage facility, while Peter O’Bryan and Associates prepared the slope stability analysis for the Selinsing and Buffalo Reef deposits.
Outotec subsidiary Outotec (RSA) designed the BIOX facility for Selinsing, while Orway Mineral Consultants was engaged for the overall plant design.
Contromation Energy Services drafted the engineering structure for the new processing units at the Selinsing gold mine.
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