Bulgaria

Ada Tepe Mine

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Overview

Mine TypeOpen Pit
StatusActive
Commodities
  • Gold
  • Silver
Mining Method
  • Truck & Shovel / Loader
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SnapshotAda Tepe is one of the highest grade open pit gold mines in the world.

Owners

SourceSource
CompanyInterestOwnership
Dundee Precious Metals Inc. 100 % Indirect
Dundee Precious Metals Krumovgrad EAD (operator) 100 % Direct
Dundee Precious Metals Krumovgrad (DPMK), a 100% subsidiary of Dundee Precious Metals (DPM), was awarded the Krumovgrad licence area (130 km2) on 12 June 2000 in accordance with the Agreement of Prospecting and Exploration reached with the Bulgarian Ministry of Economy.

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Deposit type

  • Epithermal
  • Vein / narrow vein

Summary:

The Ada Tepe deposit is a prime example of a high-level epithermal gold-silver deposit, formed during the Neogene within the Southern Rhodope tectonic zone. It is characterised as a low-sulphidation epithermal gold silver deposit. These deposit types are common throughout the world and form in association with volcanic arcs along subduction zones on plate boundaries

The Ada Tepe deposit is a low-sulphidation adularia-sericite gold-silver epithermal deposit located within Palaeocene sedimentary rocks overlying the north-eastern end of the Kessebir core complex.

The gold precipitates predominantly in the veins. The Ada Tepe deposit shows a multiphase history of formation with several brecciation and vein emplacement events resulting in complex overprinting infill stages and crosscutting relationships between the veins.

Two major styles of mineralisation are apparent at Ada Tepe:
• Initial stage of mineralisation hosted by a massive, shallow-dipping (15° north) siliceous body forming the hangingwall to the detachment and defining the contact between the core complex and overlying sedimentary rocks. This mineralisation is termed the “Wall Zone” by local geologists and displays multiple stages of veining and brecciation.

• Second phase of mineralisation represented by steep dipping veins that exhibit textures indicative of formation within an epithermal environment. These veins have a predominant east-west strike, crosscut the shallow-dipping siliceous Wall Zone mineralisation, and extend upwards into the sedimentary breccia unit above the Wall Zone. This phase of mineralisation has been locally termed the “Upper Zone”.

The initial stage Wall Zone mineralisation is interpreted to be associated with early silica flooding and relatively low gold grades. However, regions of the Wall Zone through which well-developed Upper Zone vein mineralisation passes are typically thicker, more intensely brecciated and contain epithermal vein and hydraulic breccia infill textures and associated high gold grades that are not present in regions where Upper Zone vein mineralisation is absent. These thick strongly continuous regions of high-grade Wall Zone mineralisation generally thin and diminish in grade away from and between regions of well-developed Upper Zone vein mineralisation.

Typical epithermal textures present at the Ada Tepe deposit include the following:
• Crustiform and colloform banding;
• Chalcedonic banding;
• Bladed silica replacement textures after carbonate;
• Compositionally zoned crystals;
• Hydraulic breccia textures;
• Late-stage carbonate veins.

The textural style and grade of mineralisation at Ada Tepe, high grades in association with open-space fill textures, such as bladed silica replacement after carbonate (i.e. evidence of boiling), hydrothermal breccias and also the presence of sinter material, suggests proximity to the paleo surface and a lowsulphidation nature of mineralisation.

Gold and silver mineralisation in the Krumovgrad licence area is predominantly hosted within the Shavar Formation proximal to the unconformable fault contact or detachment with the underlying basement rocks of the Kessebir core complex. Sediments within the Shavar Formation typically form laterally discontinuous lenses ranging from coarse breccia to fine sands with variable clay content. Upward variations in the stratigraphy of the Krumovgrad Group reflect progression from a high-energy environment, breccia-conglomerates and coarse sandstones through to the lower energy siltstones and limestones characteristic of increasing basin maturity.

The Ada Tepe deposit is approximately 600 m long along strike (north-south), and 300–350 m wide (east-west). The dominant structure at the Ada Tepe deposit is the detachment structure that separates the Kessebir core complex rocks (basement) from the overlying sedimentary rocks, which forms a 10–15° north-dipping lower structural bounding surface to the deposit. The deposit is bound to the north and south by approximately northeast-southwest striking, steep dipping faults.

Mapping and structural data from diamond drill core indicate that the latter stages of movement along the detachment structure at Ada Tepe post-dates emplacement of epithermal mineralisation and were responsible for translation of the hanging wall sediments (and deposit) towards 030°. Consequently, any basement feeder structures are interpreted as lying to the south and may have been eroded or are concealed beneath later graben sediment fill.

Gold precipitated in veins where the mineralisation observed macroscopically consists mainly of silica, quartz, carbonate (calcite, manganese-rich), adularia, and some opaque minerals as chalcopyrite and pyrite.

The veins occur in two domains: the “Wall Zone” and the “Upper Zone”. The term “Wall Zone” describes a siliceous body shallowly dipping 15° north, forming the hangingwall of the detachment and defining the contact between the core complex and the overlying sedimentary rocks. The “Upper Zone” is the rest of the sedimentary cover above the Wall Zone.

The veins appear as a series of east-west sub-vertical structures which extend through the Wall Zone and upwards to the Upper Zone. A series of north-south gently dipping sub-horizontal veins form the Wall Zone.

Reserves

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Mining Methods

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Comminution

Crushers and Mills

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Processing

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Production

CommodityProductUnits20232022202120202019
Gold Metal in concentrate koz  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe57
Gold Concentrate kt  ....  Subscribe  ....  Subscribe  ....  Subscribe2.7
Silver Metal in concentrate oz  ....  Subscribe  ....  Subscribe  ....  Subscribe22,519
^ Guidance / Forecast.

Operational metrics

Metrics202320222021202020192018
Tonnes processed  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe470,545 t
Annual mining rate  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
Annual processing capacity  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe840,000 t
Stripping / waste ratio  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
Ore tonnes mined  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe430,384 t157,834 t
^ Guidance / Forecast.

Production Costs

CommodityUnits20232022202120202019
Total cash costs (sold) Gold USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 425 / oz **  
Total cash costs Gold USD  ....  Subscribe  ....  Subscribe 399 / oz **  
All-in sustaining costs (sold) Gold USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 596 / oz **  
^ Guidance / Forecast.
** Net of By-Product.

Operating Costs

Currency2022202120202019
Total operating costs ($/t milled) USD 55  52.2  40.1  49.3  

Financials

Units20232022202120202019
Capital expenditures (planned) M USD  ....  Subscribe
Capital expenditures M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 36.4  
Sustaining costs M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 4  
Growth Capital M USD  ....  Subscribe 32.4  
Revenue M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 69.7  
Pre-tax Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 25.3  
After-tax Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 22.2  
EBITDA M USD  ....  Subscribe  ....  Subscribe 49.3  

Heavy Mobile Equipment

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Personnel

Mine Management

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Aerial view:

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