In the Kapan mining district, mineralisation dominantly occurs as two styles – as chalcopyritepyrite veins and stockworks and poly-metallic vein systems hosted by a volcano- sedimentary rock sequence.

The Shahumyan deposit exhibits numerous syn-volcanic dykes and sills of andesitic to gabbroic composition. Such intrusions are pre-mineralisation. Pre-mineralisation dykes often have mineralised contacts and are always subject to propylitic alteration or higher grade (typically within contacts of veins or major structures).

At Shahumyan mineralisation is hosted by a suite of sub-parallel veins, the current interpretation of the deposit includes in excess of a hundred veins. In many cases the continuity of these veins is yet to be established and future drilling will be important to validate the current model. Regardless, development along and across the vein system has confirmed the prevalence of approximate east-west strikes and steep dips of the veins.

Hydrothermal-altered breccia units are also notable within the deposit makeup. Such breccias are generally found on the eastern flank of the deposit and contain polymictic clasts (andesite, basalt, dacite) within a sulphide rich matrix. Mineralised clasts can be found which are thought to have occurred due to precipitation of sulphides within vesicular lithologies.

Mineralisation within the Shahumyan deposit is characterized by narrow veins (0.2 – 2.0 m), steeply dipping and striking approximately east-west that host a polymetallic (Cu-Zn-Pb-AuAg) mineral assemblage. Veins are often found in networks and “zones” that may be shadowed by a wide zone of argillic alteration and disseminated mineralisation. Such zones can be as wide as 25 m (for example vein 5) but typically are 10-15 m wide and appear most common in higher elevations within the deposit.

Mineralisation is primarily semi-massive to massive sphalerite, pyrite, chalcopyrite, galena and bornite and occasionally, found with the latter mineral assemblage of tennantite, tetrahedrite, bornite, enargite, chalcocite, covellite, Pb, Au, Ag, Bi tellurides and native gold and silver (recorded during petrographic analysis). Gangue minerals present are typically quartz, calcite, gypsum, anhydrite and rhodochrosite. Veins exhibit a variety of textures which relate to the numerous stages of mineralisation and tectonism that have occurred.

According to Tate (2012) the mineralogy, scale and distribution of veins and alteration are consistent with the upper parts of a large porphyry style hydrothermal system with the Shahumyan vein system representing a basement carbonate zone within the system. The Centralni stockworks represent the lower transitional parts of a high sulphidation epithermal zone within the porphyry hydrothermal system.

Access into the mine is via two decline ramps, one to access the south section of the mine, and one to access the north section. Each decline has a portal at 780 mL (all levels are expressed as metres above sea level). Previous access into the mine was via vertical shafts. These shafts are still evident, but no longer provide any facility.

Crosscuts are developed from each of the declines to intersect the veins at approximately 90° in plan. Mine levels are at 10 m vertical intervals. Veins are near vertical. As each economic vein is intersected, a vein drive is developed along the vein to open up working faces.

Sub-level open stopes are opened up along the vein drives. Each stope is typically 40 m high and 60 m along strike. Production blast holes are drilled upwards from the lower sub-level, and consist typically of 2-3 parallel holes. Current drilling is with Tamrock bar-mounted pneumatic rigs and a recently introduced Atlas Copco Simba drill jumbo. Stope holes are blasted into an initial stope raise and the stope is opened up from there. Rib pillars are left between stopes, and crown pillars are left between 40 m vertical stopes. These pillars are not presently recovered. On completion of each stoping area, i.e. an area of around 60 m on strike and 40 m in vertical height, the stope is available for filling with waste. All mine development waste is disposed of this way. The waste is not treated in any way, but does provide some support to the stope roof.

Broken material from the stope ring blasting falls to the mining drive where it is loaded by various types of load-haul-dump machines (“LHD”) directly into diesel haul trucks and hauled to the surface.

The primary crusher is a 1200 mm x 900 mm jaw, with the unit discharge (at -150 mm) feeding directly into the secondary cone crusher for reduction to 75 mm; this product is the direct feed into the KMDT 2200 tertiary cone crusher for a reduction to a nominal -25 mm. The crushed product is the feed to the grinding circuit, and is conveyed to one of two storage bunkers, each of approximately a 1,000 t storage capacity.

ROM from the bunkers is fed by conveyor to the primary mill (rod mill - 2.7m dia, by 3.6m long, 400 kW) in the plant. Oversize from the mill is fed to a second stage ball mill as the sands product from within in a closed circuit with a spiral classifier. Classifier overflow is fed to the copper flash flotation circuit. Tails from the flash flotation are passed through a second stage hydrocyclone classification with tertiary grinding through a ball mill in a closed circuit.

Run-of-mine material (ROM) from the north section is hauled out of the north decline, and transported and tipped by trucks onto the main stockpile area. The ROM from the south section is hauled and tipped in the stockpile area, again by truck. Material from either section is rehandled with a Cat 996 loader into the feed bunker during the crushing stage, while managing any oversize rocks for size reduction by a mobile rockbreaker as required.

Oversize from the mill is fed to a second stage ball mill as the sands product from within in a closed circuit with a spiral classifier. Classifier overflow is fed to the copper flash flotation circuit. Tails from the flash flotation are passed through a second stage hydrocyclone classification with tertiary grinding through a ball mill in a closed circuit. Hydrocyclone overflow is feed to the copper flotation circuit, comprising of 2 rougher and 2 scavenger cells. The rougher concentrate is cleaned in the 3 stage cleaner circuit, while ........