Mineralization in the massive sulphide deposit consists of closely packed, rounded to angular grains of pyrite (generally around 200 microns in diameter) with lesser, interstitial chalcopyrite and sphalerite (generally 5 to 50 microns in diameter). The ore mineral assemblage (in order of decreasing abundance) is pyrite, chalcopyrite, chalcocite, bornite, sphalerite, galena, and tetrahedrite. Base metal sulphides are very fine grained. Bornite, tennantite-tetrahedrite, and galena occur in trace amounts as inclusions within pyrite and filling interstices between grains. Gangue minerals include quartz, sericite, chlorite, rare calcite, and barite.

The massive sulphide deposit has been affected by supergene oxidation and copper enrichment. Chalcocite and covellite partially replace chalcopyrite, sphalerite and bornite. Copper grades of the protore, generally between 2% and 3%, are locally enriched to as much as 10%. These zones of enrichment are irregularly distributed within massive sulphide lenses and are observed above, below and within mainly primary massive sulphide lenses.

Mining of the CDMN open pit was completed in 2020, with the open pit void to be utilised as a tailings facility. Mining of the CDMN underground mine commenced in 2020 and will provide continuous production as the Cerro de Maimón South (“CDMS”) comes on track. The DR Operations underground will be extended from North to South.

In 2020 infill and extensional drilling on CDMN continued to provide better definition and higher confidence on ore lenses and provide guidance for effective mine planning. CDMN drilling in the first half of 2021 will be prioritised to define potential life of mine extensions beneath the open pit crown pillar and southerly extensions.

The crushing plant includes a jaw crusher, cone crusher and a sizing screen for 8mm product.

The ore is trucked to separate sulfide and oxide ore processing plants. The sulfide plant produces a copper, gold and silver concentrate by flotation, and a zinc flotation circuit was added in 2015 to produce a zinc-silver concentrate also. The 700 tonnes per day oxide plant produced a gold-silver precipitate and was closed in April 2015 on exhaustion of the oxide reserves. The sulfide plant has a design throughput of 1,300 tonnes per day.

The sulphide mill, sized for 1300 t/d throughput, comprises a grinding unit, flotation cells arranged for roughing-scavenging, a regrind ball mill, and cleaner flotation cells. Copper concentrate produced in flotation will be dewatered by a thickener and pressure filter prior to shipment in trucks to the port. Reagent preparation and delivery systems (lime, flotation collectors, copper sulphate and frother) are provided.