Overview
Stage | Production |
Mine Type | Underground |
Commodities |
|
Mining Method |
- Bench stoping
- Transverse stoping
- Avoca
- Uppers Retreat
- Cemented backfill
- Dry waste backfill
|
Processing |
- Carbon re-activation kiln
- Agitated tank (VAT) leaching
- Carbon in pulp (CIP)
- Elution
- Carbon adsorption-desorption-recovery (ADR)
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 2023 |
During the 2021 financial year, the Aeris Board approved the construction of a new multi-stage tailings storage facility at Cracow (TSF No.2). As at 30 June 2021 the construction was substantially complete and commissioning is targeted to occur in early August. |
Latest News | Aeris emerges as buyer of Evolution’s Cracow gold mine June 4, 2020 |
Source:
p. 121
Company | Interest | Ownership |
Aeris Resources Ltd.
|
100 %
|
Indirect
|
Lion Mining Pty Ltd.
(operator)
|
100 %
|
Direct
|
On 1 July 2020, Aeris Resources Limited, through its wholly owned subsidiary Aeris Regional Holdings Pty Ltd, acquired 100% of the issued shares in Lion Mining Pty Ltd, owner and operator of the Cracow Gold Operations (Cracow).
Deposit Type
- Vein / narrow vein
- Epithermal
- Breccia pipe / Stockwork
Summary:
The Cracow project area gold deposits are in the Lower Permian Camboon Andesite on the south-eastern flank of the Bowen Basin. The regional strike is north-northwest and the dip 20° west-southwest. The Camboon Andesite consists of andesitic and basaltic lava, with agglomerate, tuff and some inter bedded trachytic volcanics. The andesitic lavas are typically porphyritic, with phenocrysts of plagioclase feldspar (oligoclase or andesine) and less commonly augite. To the west, the Camboon Andesite is overlain with an interpreted disconformity by fossiliferous limestone of the Buffel Formation. It is unconformably underlain to the east by the Torsdale Beds, which consist of rhyolitic and dacitic lavas and pyroclastics with inter-bedded trachytic and andesitic volcanics, sandstone, siltstone, and conglomerate.
Mineralisation is hosted in steeply dipping low sulphidation epithermal veins. These veins found as discrete and as stockwork and are composed of quartz, carbonate and adularia, with varying percentages of each mineral. Vein textures include banding (colloform, crustiform, cockade, moss), breccia channels and massive quartz, and indicate depth within the epithermal system. Sulphide percentage in the veins are generally low (<3%) primarily composed of pyrite, with minor occurrences of hessite, sphalerite and galena. Rare chalcopyrite, arsenopyrite and bornite can also be found.
Alteration of the country rock can be extensive and zone from the central veined structure. This alteration consists of silicification, phyllic alteration (silica, sericite and other clay minerals) and argillic alteration in the inner zone, grading outwards to potassic (adularia) then an outer propylitic zone. Gold is very fined grained and found predominantly as electrum but less common within clots of pyrite.
Mining Methods
- Bench stoping
- Transverse stoping
- Avoca
- Uppers Retreat
- Cemented backfill
- Dry waste backfill
Summary:
Mining activities during the financial year were focused on improving development and backfilling rates, testing the limits of mining capacity.
There are 15 separate deposits being mined, all by underground methods. The Ore Reserve estimate reported is a consolidation of the estimates for the fifteen deposits. Fourteen of the deposits are accessed via the Cracow mine infrastructure. The Roses Pride mine infrastructure is three kilometres to the North of the main Cracow mine.
Several mining methods are used for the extraction of stopes at Cracow:
• Modified Avoca. This is the primary method of extraction at Cracow. A bottom-up extraction method. Stopes are backfilled with dry rockfill;
• Uphole retreat. A method used on the top level of an orebody or in a sill pillar. Stopes remain open as there is no backfill horizon;
• Benching. Used on the bottom level of an orebody to extract ore that would not be economical to mine conventionally (capital costs associated with another level below); and
• Transverse stoping. A method used in wider (>15m) areas to ensure maximum recovery.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Jaw crusher
|
.......................
|
42" x 30"
|
|
1
|
Cone crusher
|
.......................
|
4.25'
|
|
2
|
Ball mill
|
.......................
|
4.0m x 5.9m
|
1400 kW
|
1
|
Ball mill
|
.......................
|
2.9m x 4.3m
|
450 kW
|
1
|
Vertical mill / Tower
|
.......................
|
|
500 kW
|
1
|
Summary:
The Cracow processing plant consists of a three-stage crushing circuit, primary and secondary ball milling.
Primary crushing/grinding plant/machinery:
- Jaw: Jaques 42x30;
- Secondary: 4 ¼ ft cone crushers;
- Tertiary: 4 ¼ ft cone crushers.
Grinding plant equipment:
- ML01: 4m x 5.9m Morgardshammer OFBM, 1400KW;
- ML02: 2.9 x 4.3 Morgardshammer OFBM, 450KW;
- HIG01: Outotec HIG500, 500kW.
Grinding media:
- 40mm and 60mm high chrome grinding balls (ball mills);
- 3mm ceramic beads (HIG mill).
Screening plant/equipment:
-Jaques Torrens double deck screen, top deck passing
-24mm, bottom deck passing 10mm
Processing
- Carbon re-activation kiln
- Agitated tank (VAT) leaching
- Carbon in pulp (CIP)
- Elution
- Carbon adsorption-desorption-recovery (ADR)
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
Cracow ore processing plant achieved annual 603,000 tonnes - (exceeding the previous assumed limit of 570,000 tonnes per annum) and monthly (57,100 tonnes) throughput records in FY2021. These records were achieved with minor capital expenditure on debottlenecking of the processing plant, particularly in the crushing circuit. The proved higher processing capacity is a factor in extending the life of Cracow as it enables lower gold cut-off grades to be contemplated.
During the year construction of a new multi-stage tailings storage facility at Cracow (TSF No.2) commenced. Cracow is currently discharging tailings into Tailing Storage Facility No.1 (TSF No.1), which has reached its maximum allowable construction height.
CRACOW ORE PROCESSING PLANT
The Cracow processing plant consists of a three-stage crushing circuit, primary and secondary ball milling, pre-leach thickening, fine grinding and conventional cyanidation leaching (CIP).
-Ore treatment/pro ........

Recoveries & Grades:
Commodity | Parameter | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 |
Gold
|
Recovery Rate, %
| ......  | ......  | ......  | 94.3 | 94.6 | 93.1 |
Gold
|
Head Grade, g/t
| ......  | ......  | ......  | 5.63 | 5.45 | 5.92 |
Reserves at June 30, 2021:
Mineral Resource cut-off grade 1.5g/t Au for all Cracow deposits
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
172 kt
|
Gold
|
4.9 g/t
|
27 koz
|
Probable
|
519 kt
|
Gold
|
3.8 g/t
|
63 koz
|
Proven & Probable
|
690 kt
|
Gold
|
4.1 g/t
|
90 koz
|
Measured
|
200 kt
|
Gold
|
9.1 g/t
|
59 koz
|
Measured
|
200 kt
|
Silver
|
5.7 g/t
|
37 koz
|
Indicated
|
1,400 kt
|
Gold
|
3.7 g/t
|
170 koz
|
Indicated
|
1,400 kt
|
Silver
|
3.1 g/t
|
140 koz
|
Measured & Indicated
|
1,600 kt
|
Gold
|
4.3 g/t
|
230 koz
|
Measured & Indicated
|
1,600 kt
|
Silver
|
3.4 g/t
|
180 koz
|
Inferred
|
2,300 kt
|
Gold
|
2.3 g/t
|
170 koz
|
Inferred
|
2,300 kt
|
Silver
|
1.5 g/t
|
110 koz
|
Total Resource
|
3,900 kt
|
Gold
|
3.1 g/t
|
390 koz
|
Total Resource
|
3,900 kt
|
Silver
|
2.3 g/t
|
290 koz
|
Aerial view:
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