📋 Tender Overview
Estimated Investment Lower mine: $280m
Scope :
The Marmato underground gold mine located in Colombia is being extended to the lower mine.
The Marmato gold mine project in Colombia’s Marmato district is an operating underground mine. A pre-feasibility study (PFS) was completed in June 2022 to extend the mining operations to the lower mine.
Colombian company Aris Mining is the owner of the project. The upper mine has been in operation since 1993 and produces up to 26.8 thousand ounces (koz) of gold a year. The lower mine will be developed as an extension to the upper mine.
The current life expectancy of the upper mine is 19.5 years, while the lower mine is projected to operate for approximately 18 years.
Construction at the lower mine began in September 2023 while production is scheduled to commence in September 2024, with full production anticipated by 2026. The development cost of the lower mine is estimated at $280m.
Marmato gold project location
The Marmato mine is located in the Marmato gold district in the mountainous Caldas region. The mine lies 80km south of Medellin and 200km north-west of Bogota.
The mining development encompasses the Zona Baja and Echandia mining titles.
Geology and mineralisation of the Marmato site
The Marmato deposit is part of the east-west cordillera of the Colombian Andes, housed within the Marmato Porphyry suite, which is noted for its andesitic to dacitic intrusions, with characteristic mineral features.
The upper mine features epithermal mineralisation with an array of sulfide-rich veins while the lower mine’s mineralisation is more mesothermal with fine veinlets and porphyry-hosted minerals.
Gold and silver reserves at Marmato
The proven and probable ore reserves at the Marmato mine are estimated to be 31.2 million tonnes (mt), grading 3.16g/t of gold and 6.1g/t of silver with contained gold of approximately 3,178koz and silver of 6,138koz as of June 2022.
Mining method
The upper mine is currently mined using conventional cut-and-fill stoping methods. The narrow vein mineralisation style changes to a large porphyry mineralised zone at the base of the upper mine, where the long hole stoping and drift and fill methods are used.
The upper mine currently has six production levels, with the highest level at Level 16, and the lowest at Level 21, and one level in development. The mining level accesses proceed horizontally from the main portal at the surface to horizontal cross-cuts.
Each level is 50m apart vertically, except Level 20, which is 60m from Level 19. Level 18 serves as the main haulage level and the primary access for the mine.
Mineralisation at the lower mine occurs below the upper mine and approximately 800m to 1,400m below the surface level and will employ underground long-hole stoping methods. The lower mine deposit will be mined in blocks from bottom to top with the use of paste backfill for support.
The stopes will be 20m wide and 25m high with vary
