This report details the processing route, equipment specifications, and historical operating data for the Geghanush mine, as of 2014.
Report context
The 2014 NI 43-101 Technical Report covers the Geghanush mine’s processing plant design, current operating strategy, and planned upgrade to one million tonne per annum capacity. The report presents both the existing processing route and the proposed second mill line refurbishment, along with historical metallurgical performance data and testwork results.
Processing route
Crushing
Run-of-mine (ROM) material from the north and south sections is tipped onto the main stockpile area and rehandled by a Cat 996 loader into the feed bunker. Oversize rocks are managed by a mobile rockbreaker as required. The primary crusher is a 1200 mm x 900 mm jaw crusher, discharging at -150 mm directly into the secondary cone crusher for reduction to 75 mm. This product feeds the KMDT 2200 tertiary cone crusher for reduction to a nominal -25 mm. The crushed product is conveyed to one of two storage bunkers, each of approximately 1,000 t capacity.
Grinding
Crushed ROM is fed by conveyor to the primary rod mill (2.7 m diameter by 3.6 m long, 400 kW). Oversize from this mill feeds a second-stage ball mill as the sands product in closed circuit with a spiral classifier. Classifier overflow feeds the copper flash flotation circuit. Flash flotation tails pass through second-stage hydrocyclone classification with tertiary grinding through a ball mill in closed circuit. Hydrocyclone overflow is feed to the copper flotation circuit.
Copper flotation
The copper flotation circuit comprises two rougher and two scavenger cells. Rougher concentrate is cleaned in a three-stage cleaner circuit. Scavenger concentrate is combined with first cleaner tails and returned to the rougher feed. Flash flotation is also included before the main copper flotation circuit.
Zinc flotation
Copper scavenger tails form the feed to the zinc circuit, comprising six rougher and eight scavenger cells. Rougher concentrate is cleaned in a three-stage cleaner circuit. Scavenger concentrate is combined with first cleaner tails and returned to the rougher feed.
Concentrate handling
Copper and zinc concentrates are thickened by 24 m thickeners and filtered by drum filters to produce a final dry concentrate. Normal moisture content is around 7%. When flocculant is used to speed settlement of fine material, moisture content increases to around 11%. Copper concentrate is shipped in bulk bags by truck to Yerevan, then by rail to the port of Poti in Georgia. Zinc concentrates follow the same route but are shipped in bulk containers.
Upgrade plan (proposed design)
DPMK plans to refurbish the original second mill line, comprising three mills (one rod and two ball), a spiral classifier, and a crushed material bunker. This includes replacing the complete mill feed system, installing a hydrocyclone battery, and adding several new flotation units to upgrade capacity. The upgrade is intended to double the current grinding circuit capacity and introduce additional flotation capacity. The estimated cost for the mill upgrade is $6 million, with an additional $13.4 million required to upgrade the existing tailings management facility.
Tailings management
Final tailings are pumped to the current tailings management facility at Geghanush, located in a valley with a north and south wall. The north wall was raised in April 2012; together with the previously raised south wall, the facility has a life of 10 years at 600,000 tpa. A water decant reclaims water for mill operation, currently consisting of 70% reclaim water from the TMF and 30% fresh make-up water. The previous Artsvanik dam TMF is closed and has been rehabilitated.
Key reported parameters
| Parameter | Unit | Design / Actual / Testwork Basis |
|---|---|---|
| Current plant feed rate | t/h (t/d) | Actual: ~70 t/h (1,700 t/d) |
| Maximum recorded capacity, one line | t/d | Actual: ~2,100 t/d |
| Primary crusher | mm | Design: 1200 x 900 jaw crusher |
| Primary crusher discharge size | mm | Design: -150 mm |
| Secondary crusher product | mm | Design: 75 mm |
| Tertiary crusher product, nominal | mm | Design: -25 mm |
| Primary rod mill dimensions | m | Design: 2.7 dia x 3.6 long, 400 kW |
| Storage bunker capacity, each | t | Design: ~1,000 |
| Copper flotation cells: rougher | count | Design: 2 |
| Copper flotation cells: scavenger | count | Design: 2 |
| Zinc flotation cells: rougher | count | Design: 6 |
| Zinc flotation cells: scavenger | count | Design: 8 |
| Copper recovery to final concentrate | % | Actual: 85%; target: 90% |
| Gold recovery to copper concentrate | % | Actual: 68–74% |
| Gold grade in copper concentrate | g/t | Actual: 90–110 |
| Copper concentrate grade | % Cu | Actual: 20–22 |
| Zinc concentrate grade | % Zn | Actual: 58–63 |
| Additional gold distribution to zinc concentrate | % | Actual: 10–15 |
| Overall site gold recovery | % | Actual: 80–85 |
| Concentrate moisture, normal | % | Actual: ~7 |
| Concentrate moisture, with flocculant | % | Actual: ~11 |
| Thickener diameter | m | Design: 24 |
| Mill upgrade estimated cost | $ | Proposed: 6 million |
| TMF upgrade estimated cost | $ | Proposed: 13.4 million |
| Current TMF life at 600,000 tpa | years | Actual: 10 |
Project website: https://miningwatch.ca/blog/2021/8/6/inv-metals-loma-larga-project-acquired-canadian-company-toxic-environmental-record
Technical qualifications
This report presents a 2014 snapshot of the Geghanush mine processing plant. The report does not specify whether the proposed upgrade to 1 Mtpa has been completed, nor does it contain current ownership, economic performance, or operational status information beyond 2014. The reported metallurgical balance for the life of mine (2016–2024) is a prediction. No testwork data or flowsheet details beyond what is explicitly stated in the original report are available. The report does not provide specific design parameters for all equipment, nor does it include detailed performance data for the proposed second mill line beyond the scope of the upgrade plan.
Source: Dundee Precious Metals Inc. NI 43-101 Technical Report, Report No. R127.2014, sections 17 and 17.2.
