The Timok deposit is located within the central part of TMC, in the Bor District of northeastern Serbia. The project area is approximately five kilometres south of the mining municipality of Bor. The TMC comprises a series of andesitic to dacite-andesitic subvolcanic, volcanic and volcano-sedimentary sequences and plutonic intrusions (mainly monzonite to diorite and granodiorite compositions). The TMC is generally erosionally well-preserved when compared with both the Banat and Panagyurishte segment belts to the north in Romania and to the east in Bulgaria respectively. The largest porphyry and porphyry-epithermal deposits in the Timok segment are represented by the Majdanpek and Bor copper and gold deposits which are hosted within in Upper Cretaceous andesitic volcanic units.

The Cenomanian sedimentary rocks are conformably overlain by volcanic, volcaniclastics and sedimentary units of the Upper Cretaceous TMC. The TMC complex is dominated by Late Cretaceous (Turonian to Campanian) andesitic lavas, lava domes and shallow intrusions, volcaniclastic and epiclastic units and basaltic andesites, volcaniclastics and clastic sedimentary rocks that formed in an extensional rift basin.

The TMC andesite volcanic rocks are typically calc-alkaline in composition. Kolb et al. (2013) describe a geochemical signature similar to adakites, which are commonly associated with porphyry and epithermal copper and copper-gold deposits elsewhere in the world. The western and eastern borders of the TMC complex are structurally controlled by major faults. In the centre and southeast of the TMC, Miocene clastic sedimentary rocks unconformably overlie the Late Cretaceous units.

Timok Upper Zone is a high-grade HS epithermal deposit typically associated with an advanced argillic alteration system with a discrete footprint.

The top-third of the HS epithermal mineralization of the UZ is characterized by a massive sulphide lens located on the top of a volcanic to volcaniclastic sequence. This lens has a variable but overall similar dip to the overlying stratigraphy. With increasing depth from the top of the UZ, the proportion of massive sulphide mineralization intruding or replacing the host rock reduces, as does the sulphide content and presence of fragmental volcanic units. With depth, the mineralization becomes more characterized by veins and stockworks hosted by more coherent andesite.

The massive sulphide comprises mainly pyrite and covellite and hosts the highest grades of copper and gold; multiple pyrite replacement phases are observed, which in some places comprise up to 95 wt% of the deposit. Locally, different pyrite phases can be recognized by cross-cutting relationships; however, in general they are difficult to distinguish. Covellite is interpreted to be later than pyrite and is observed transgressively cutting and brecciating massive pyrite; however, pyrite can also locally be observed cross-cutting covellite stringers or massive aggregates of covellite flakes intergrowing with alunite.

Pyrite with enargite is also present. Enargite is commonly observed rimmed and sometimes replaced by covellite and is therefore interpreted to represent an earlier phase of mineralization.

Mineralized hydrothermal breccias have also been locally observed in the UZ and at least two events have been recognized: an early syn-mineralization phase and an inter-mineral phase, hosting fragments of massive sulphide.

Gold mineralization is present in a number of forms, including tellurides such as calaverite (Au), sylvanite (Au-Ag) and kostovite (Au-Cu), altaite (Pb) and is mostly hosted in pyrite but also locally found encapsulated in bornite (Cornejo, 2017). Native gold is not common; however, where observed it is very fine, approximately 2 to 6 µm in diameter.

Low temperature galena and sphalerite as disseminations and in veins are noted in the peripheral zones of the UZ mineralization, mostly related to kaolinite-pyrite alteration fronts.

The recommended strategy for mining the orebody is Subleve Caving (SLC) method. A sensitivity analysis showed that the selection of this strategy was robust across a wide range of assumptions.

In SLC, mining starts at the top of the orebody and progresses downwards. Mineable resource is extracted from sublevels spaced at regular vertical intervals throughout the deposit. A series of ring patterns are drilled and blasted from the drawpoints on each sublevel; broken mineable resource is mucked from the drawpoints after each ring blast.

SLC is applicable through a wide range of geotechnical conditions, but as with most mining methods it is most efficiently applied in strong rock conditions, making it a relatively easy method to mechanize. This method is normally used in massive, steeply-dipping orebodies with considerable strike length. SLC typically has dilution ranging from 15 to 30% and mining recovery ranging from 80 to 90%, and is dependent on effective management of the SLC operations.

The production rate is a function of the deposit geometry and continuity, the prevailing ground conditions, the number of available stoping areas, and the expected productivity for each stope. The production resources were scheduled to achieve a practical production output. The expected drawpoint productivity has been limited to 260 tonnes per drawpoint per day, based on benchmarking comparable mines. This productivity rate results in annual targets of 3.00 Mtpa for the SLC operations and an additional 0.25 Mtpa for development, providing 3.25 Mtpa of feed to the processing plant.

The major surface mine infrastructure required to support the operation of the Timok Mine will include:
- Mine Portal.
- Overland Conveyor System.
- Water Storage.
- Surface Pipelines.
- Fans for Main Ventilation System.

Primary Crushing
The primary crusher is located underground. Process feed is crushed to minus 150 mm in a jaw crusher which is fed by a vibrating grizzly feeder. The material is then conveyed via decline conveyor to the mill.

Timok will have two underground primary crushers. One crusher will be located on the -275 m level, and the second crusher will be located on the -435 m level. Both primary crushers will be jaw crushers. Only one crusher will be operational at a time.

Both crushers will be identical in size, and for the purpose of this study Metso C130 jaw crushers were selected. The nominal capacity of each crusher will be 468 tph (tonnes per hour), however each crusher will have a design capacity of 585 tph. These capacities are overall, and account for scalped material throughput. Each crusher will be capable of reducing feed material of 750 mm minus to 220 mm minus. The 750 mm minus is driven by the size of the rockbreaker station grizzly openings. The 220 mm minus requirement is driven by the CDI conveyor system which has a design capacity of 800 tph, and has a maximum allowable lump size of 220 mm.

The crushed process feed is transferred to the process plant via an overland conveyor. The overland conveyor discharges onto the top of the coarse feed storage bins via a shuttle conveyor. Discharge can be to either of the two coarse feed storage bins or via a chute to a stockpile. Each coarse feed bin has 4,500 t live capacity and the two bins combined provide 24 hours storage capacity for the grinding circuit.

Primary Grinding Circuit
The grinding line consists of a single variable speed SAG mill, followed by a single ball mill operating in closed circuit with a cyclone cluster. The product from the grinding circuit (cyclone overflow) has a typical size of 80% passing 75 µm. SAG mill pebbles are recycled to the SAG mill feed conveyor.

The SAG mill feed conveyor discharges mineralized material, along with pebble recycle and grinding media, into the feed chute of the SAG mill together with mill feed dilution water and lime slurry. The SAG mill is fitted with discharge grates to retain grinding media and larger pebbles while allowing smaller particles to discharge from the mill. SAG mill grinding media is also added to the SAG mill feed chute with a 1-t kibble with a false bottom.

The SAG mill trommel undersize gravitates to the primary cyclone feed hopper where it is combined with the discharge from the ball mill. The slurry is transported to a single cyclone cluster using two variable-speed cyclone feed pumps (duty and stand-by).

SAG mill balls are added via a ball addition system and bunker adjacent to the SAG mill feed conveyor. A separate ball storage bunker is provided for the ball mill. The ball mill has a dedicated ball charging system.

A SAG mill feed chute removal system and a ball mill feed chute removal system are used to service the mills. A liner handler is provided for each mill.

The process plant is designed to treat nominally 8,900 tonnes per day (equivalent to 3.25 million tonnes per year) and produce concentrates.

The Timok process plant includes the following unit processes and associated facilities:
- Primary crushing located underground.
- Overland conveying of crushed process feed.
- Coarse feed storage bins and reclaim.
- SAB grinding circuit.
- Copper flotation comprising rougher flotation, concentrate regrind and two stage cleaning.
- Copper concentrate thickening and filtration.
- Copper concentrate load out and storage for each concentrate.
- Tailings storage and water reclaim.
- Effluent treatment.
- Reagents storage and distribution (including lime slaking, flotation reagents, water treatment and flocculant).
- Grinding media storage and addition.
- Water services (including fresh water, fire water, gland water, cooling water and process water).
- Potable water treatment ........