Overview
Stage | Permitting |
Mine Type | Underground |
Commodities |
|
Mining Method |
|
Processing |
- Filter press plant
- Flotation
|
Mine Life | 8.4 years (as of Jan 1, 2014) |
Rathdowney Resources Ltd. is focused on advancing Project Olza through the permitting process toward a mining license and into production. |
Latest News | Rathdowney Closes First Tranche of Private Placement August 6, 2021 |
Source:
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Rathdowney Resources holds a 100% interest in Project Olza through its wholly owned subsidiary, Rathdowney Polska Sp z o.o.
Summary:
Project Olza hosts a Mississippi Valley type zinc-lead deposit.
The property comprises three adjoining Exploration Concessions for the prospecting and exploration for zinc and lead ores. The Zawiercie, Rokitno, and Chechlo concessions are approximately 60 km northwest of the city of Krakow in southern Poland, and have a total surface area of 152.65 km2 .
The Project is within the North European Plain, a relatively flat area with an average elevation between 300 to 350 m above sea level. Within the project area, there is land available for potential surface facilities to support a proposed underground mine and associated processing infrastructure.
Project Olza lies within the Upper Silesian Mining district, near the boundary between the Caledonian Krakow-Myszkow structural zone and the Variscan Upper Silesian coal basin. Zinc and lead deposits in Upper Silesia are principally hosted by dolomites of the Middle Triassic Muschelkalk Formation but locally zinc and lead mineralization also occurs in older rocks, including Devonian limestone and dolomite. In the southwestern part of the district, the Triassic host rocks overlie Upper Carboniferous Coal Measures. However, in the northeastern part of the district, where Project Olza is located, the Triassic rocks transgressively overlap the erosional paleosurface of the Lower Carboniferous and Devonian carbonates, and the PermoCarboniferous strata are missing. Below this succession lie Lower Paleozoic sedimentary, metamorphic, and igneous rocks that comprise the strongly folded Variscan-Caledonian basement.
An important control of the mineralization in the essentially flat-lying Mesozoic rocks of the Upper Silesian district is sub-vertical extensional faulting.
The bulk of zinc-lead mineralization in the district is hosted by the 30 to 80 m thick ore-bearing dolomite (OBD), a zone of epigenetic hydrothermal alteration largely coincident with the Middle Triassic Muschelkalk beds and distinct from the earlier, regional-scale, diagenetic dolomitization. While this zone of dolomitization is largely restricted to the strata of the Lower Muschelkalk Formation, it does locally extend into the underlying Devonian carbonates and the overlying MiddleUpper Muschelkalk dolomites.
Mineralization
The zinc-lead deposits are essentially stratiform to podiform bodies, occurring as replacement karstic cavity infill and collapse breccia mineralization. Thicknesses of these stratiform deposits are irregular but they can range up to 10 m or so. The lateral extent of individual pods or lenses also varies but is typically several hundred meters. Breccia-pipe and vein-type mineralization also rarely occurs. Deposit mineralogy is dominated by sphalerite and galena, with associated marcasite, and subordinate calcite, dolomite and locally barite. Silver is largely associated with sphalerite.
Summary:
The proposed approach in the PEA considers mining the Olza zinc and lead deposit at a target production rate of 6,000 tonnes per day (“tpd”) or 2.16 million tonnes per annum (“Mtpa”) using variations of underground Room and Pillar (“R&P”) methods with an unconsolidated coarse sand backfill. The sand fill will be contained within rock pillars and timber barricades and is expected to fill fairly tight to the backs of the stopes. The coarse sand is sourced from local quarries and will be transported to the Olza Process Facilities at the site of the historic cement plant via rail.
The mine would be accessed by two declines, and mined material would be moved to the surface by a conveyor along one of these declines.
To facilitate underground access and to expedite the construction schedule two separate declines will be constructed. A decline will be driven from the proposed site of the process plant to intersect with the main haulage drift. This decline ‘CD1’ would be excavated to sufficient width to accommodate a conveyor. A second decline ‘TD1’ would be driven in close proximity to the main portion of the currently defined resource. This second decline would be used for transport of men, equipment and materials to expedite the underground development.
A 3D geological model created to understand the orientation of the mineralization and the spatial variability of the resource drilling shows the mineralization is sub horizontal to shallow dipping ±15°, and strata bound at depths 80 to 140 m below surface. In parts of the mineralization, the dip increases to 40°.
The minimum mining height used in the PEA of 2 m is based on the practical operating height for low profile mining equipment.
It is expected that the average mining height will be 3.5 to 5 m based on the current resource model; production stope heights extend up to 10 m in isolated areas however.
Three separate geotechnical zones required for analysis of the underground conditions are defined as the hangingwall (back or roof), mineralization and footwall. To create these zones, a surface was defined 15 m above and below the mineralized envelope to refine the dataset. The conclusions from data interpretation, analysis and reporting are:
• The morphology and geometry indicates that the thickness of mining is generally greatest in the center of a mineralized zone;
• Variability in geometry, dip and thickness of the mineralized zones is known to exist;
• At 80 m mineralization depth, a pillar width to height (W / H) ratio of 1:1 is acceptable to maintain pillar stability in the short term indicated by an acceptable pillar Factor of Safety of 1.3, with sand backfill placed for long term stability of excavations to reduce risk of surface subsidence. Analysis has been undertaken at 2, 5 and 10 m pillar heights;
• At 140 m mineralization depth, a W / H ratio of 1.4 is acceptable to maintain pillar stability in the short term with sand backfill placed for long term stability of excavations to reduce risk of surface subsidence. A greater knowledge of the rock mass is required to refine this ratio; and
• Extraction ratios are controlled by mining height and depth below surface.
Equipment selection is based on production requirements and stope dimensions. Standard underground boom jumbos, loaders (LHD) and haul trucks have been selected to mine areas in excess of 3.5 m in thickness and low profile equipment have been costed for use in those areas less than 3.5 m thick.
Initial underground mine development will be completed by appropriate contractor(s). All other underground development and production activities will be completed by the Owner’s mining team.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Jaw crusher
|
|
1200mm x 1600mm
|
|
1
|
SAG mill
|
|
|
|
1
|
Ball mill
|
|
|
|
1
|
Processing
- Filter press plant
- Flotation
Flow Sheet:
Summary:
A surface plant would be constructed at site and employ Semi-Autogenous Grinding (“SAG”) and ball milling, followed by standard flotation treatment to produce marketable, zinc and lead concentrates for shipment to smelters.
Based on preliminary metallurgical testwork, mill feed will be ground to P80 and subjected first to lead flotation at natural pH with one cleaning stage to produce a lead concentrate grading 70% Pb.
The lead flotation tails would be subjected to zinc flotation at elevated pH with one cleaning stage to produce a zinc concentrate grading 56% Zn. Based on the quality of zinc concentrate produced in the lock cycle test, which were low in iron (<0.5% Fe) and magnesium (<2%), acid leaching of the zinc concentrate has not been included in the process.
Tailings slurry will be discharged to the lined Tailings Management Facility with reclaim water recycled for re-use in the mill process.
With a mill throughput of 2.16 Mtpa, it is ........

Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Zinc
|
Recovery Rate, %
| 89 |
Zinc
|
Head Grade, %
| 4.98 |
Zinc
|
Concentrate Grade, %
| 56 |
Lead
|
Recovery Rate, %
| 88.5 |
Lead
|
Head Grade, %
| 1.5 |
Lead
|
Concentrate Grade, %
| 70 |
Projected Production:
Commodity | Product | Units | Avg. Annual | LOM |
Zinc
|
Concentrate
|
kt
| 164 | 1,275 |
Zinc
|
Payable metal
|
M lbs
| | 1,338 |
Zinc
|
Metal in concentrate
|
M lbs
| 197 | 1,574 |
Lead
|
Concentrate
|
kt
| ......  | ......  |
Lead
|
Payable metal
|
M lbs
| | ......  |
Lead
|
Metal in concentrate
|
M lbs
| ......  | ......  |
Operational Metrics:
Metrics | |
Daily ore mining rate
| 6,000 t * |
Ore tonnes mined, LOM
| 16,646,573 t * |
Tonnes milled, LOM
| 16.1 Mt * |
Annual milling rate
| 2.16 Mt * |
Annual ore mining rate
| 2.16 Mt * |
* According to 2014 study.
Reserves at July 16, 2014:
A minimum cut-off of 2% Zn was used in the resource tabulation.
Category | Tonnage | Commodity | Grade | Contained Metal |
Inferred
|
24.4 Mt
|
Zinc
|
5.53 %
|
2,975 M lbs
|
Inferred
|
24.4 Mt
|
Lead
|
1.49 %
|
802 M lbs
|
Inferred
|
24.4 Mt
|
Lead / Zinc
|
7.02 %
|
|
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