The Suzdal deposit is located on the northwest flank of the Western Kalba gold-bearing belt, Semipalatinsk Irtysh Region (Semey Ertis), Eastern Kazakhstan, in which numerous gold deposits and gold occurrences of different types are hosted in carbonaceous black shales and clastic rocks of Carboniferous age (Kovalev et al., 2009). The Western Kalba belt is considered a terrigenous accretionary complex, located between island arcs of Devonian–Carboniferous age–Rudnyi Altai in the north-east and Zharma-Saur to the south-west, and divided into two metallogenic zones. The Char – Zimunai Belt with Ni-Co and Au mineralization on the southwest and the West Kalba-Koksentau gold zone in the northeast (Kovalev et al., 2012).

The Suzdal deposit is located at the juncture of the NW-trending Char-Gornostai-Zimunai and NE- trending Suzdal fault zones, hosted in carbonaceous carbonate-clastic rocks of the Arkalyk Formation of Serpukhovian stage. These rocks are thrust northeastward over the continental deposits of the Maitubinsk Formation, along the NW-trending Gornostai overthrust.

The host rocks of the deposit comprise calcareous and carbonaceous siltstone, marl alternating with limestone lenses, and limestones. The mineralization is located within a 4 km long and 300 to 400 m wide, NE-trending Suzdal fault-controlled zone as SW-oriented en-echelon structures with dips of 40° to 90° SE (Kovalev et al., 2009).

Gold deposits hosted in carbonate and clastic sedimentary rocks are usually compared with the Carlin-type deposits. While there are several variants of Carlin-type deposits suggested, the Suzdal deposit shows similarities to two subtypes; those hosted in carbonaceous carbonate clastic rock and those hosted in black shale. Although genesis of gold mineralization is still in controversy, a multistage and polygenic character for mineralization in Suzdal deposit is proposed. Most of the gold mineralization is concentrated in silicified and decalcified calcareous polymictic breccias of both sedimentary and tectonic origin, typical of most Carlin-type deposits.

Suzdal underground mine comprises three main ore zones, Zone 2, Zone 4 and Zone 137. Workings currently extend to 610 m below surface and will reach 800 m depth upon depletion of the current Ore Reserves.

Development mining is achieved using modern electro-hydraulic single and twin boom drill jumbos to drill blastholes, diesel powered load-haul-dump loaders (“LHD”) to clean the blasted rock from each blasted advance, and diesel powered articulated dump trucks (“ADT”) to haul broken rock to surface (ore) or to underground voids to be used as backfill.

Production is achieved using variants of the long-hole sub-level open stoping method, either top-down “uphole benching” with eventual backfilling, or bottom-up “Avoca” progressively backfilling each sublevel.

Blastholes are drilled using dedicated electro-hydraulic long-hole drill rigs, blasted ore is removed with LHD and ore is transported to surface with ADT.

Surface is accessed through four transport declines with 8° inclination. Three declines exit the mine through previously mined open pits, while the fourth, from Zone 4, exits through a dedicated box-cut excavation. Development waste is used for backfilling and is transport from development faces to filling locations by LHD or truck.

Stability of the workings is maintained by the installation of ground support (friction anchors, mesh sheets, shotcrete), leaving supporting pillars of ore unmined, for later extraction, and filling mined stopes with development waste as backfill when strategically required.

Crushing
The crushing circuit consists of three stages, a primary jaw crusher and secondary and tertiary cone crushers. The jaw crusher is in open circuit, and there are scalping screens ahead of each of the cone crushers, which otherwise operate in open circuit. The product from the crushing circuits is nominally -15 mm.

Grinding
The grinding circuit consists of three 2.7 m diameter, 3.6 m long ball mills (380 kW each). Two are configured as primary mills and operate in parallel. These mills operate in closed circuit with a screw classifier. Classifier undersize reports to hydrocyclones, the overflow of which reports to flotation. Cyclone underflow reports to the third ball mill, which also operates in closed circuit with a screw classifier.

The Suzdal process plant treats refractory sulphide-hosted gold ore through a plant incorporating flotation and bacterially assisted oxidation of the sulphide ahead of gold recovery using a carbon-in-leach (“CIL”) circuit. Doré is produced on site.

Following an earlier heap leach facility on site, the sulphide plant commenced operation in 2005 with a plant capacity of 300 ktpa of ore. In 2010, the plant capacity was expanded to its current capacity of approximately 575 ktpa of ore.

Flotation
The flotation circuit consists of two roughing stages, scavenging and two stages of cleaning. The first rougher stage uses two parallel trains of three 16 m3 mechanically agitated cells, producing final concentrate. Tailings from this stage are reground using two 2.7 x 3.6 ball mills in closed circuit with cyclones, with a target product size of 75-80% - 75 ?m. The second rougher stage consists of eight 16 m3 cells, which is followed by scavenging, using six 40 m3 cells. ........