Overview
Stage | Production |
Mine Type | Open Pit & Underground |
Commodities |
|
Mining Method |
- Truck & Shovel / Loader
- Longhole open stoping
|
Processing |
- Gravity separation
- Smelting
- Intensive Cyanidation Reactor (ICR)
- Filter press plant
- Concentrate leach
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- Carbon adsorption-desorption-recovery (ADR)
- AARL elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 2027 |
Mt Morgans Gold Operation (MMGO) comprises a 2.5 Mtpa CIL treatment plant, the Jupiter open pit and Westralia underground mining areas. |
Latest News | Dacian plots comeback following WA labour shortages April 30, 2021 |
Source:
p. 36, 85
Mt Morgans Gold Operation is 100% owned by Dacian Gold Ltd.
Deposit Type
- Banded iron formation hosted
- Vein / narrow vein
- Mesothermal
- Intrusion related
Summary:
All Dacian Gold deposits are located within the Yilgarn Craton of Western Australia.
The Westralia (including Morgans North) deposits banded iron formation (BIF) hosted sulphide replacement, mesothermal Archaean gold deposits comprising sedimentary packages composed predominantly of BIF but also including chert, mudstone, shales, conglomerate and minor felsic volcaniclastic rocks. All are intercalated within or separated by ultramafic volcanic rocks and variably intruded by felsic porphyry dykes and lamprophyres. Gold mineralisation is associated with microscopic quartz carbonate veinlets within BIF. BIF acts as the primary host for mineralisation though other rock types including basalt, porphyry intrusive and ultramafic may also be mineralised in smaller volumes and with less continuity.
The Jupiter deposit is interpreted to comprise structurally controlled mesothermal gold mineralisation related to syenite intrusions within altered basalt. A majority of mineralisation is associated with large shallow east dipping shears, with significant mineralisation developing where these shears cross cut syenite intrusions or the altered basalt proximal to the syenite intrusions. A number of small structures in the form of shears, faults and veins dip either steeply to the west, or moderately towards the north-west, north and/or north-east.
At Maxwells, gold mineralisation is hosted within the BIF and is mineralised over a strike length of ~1km. Gold mineralisation is best developed in the regolith profile, although bedrock mineralisation is also present. The thicker mineralized packages and higher grades (up to 29.40g/t) appear to occur when high strain structures cross-cut the BIF, causing brittle deformation. Quartz veining is also found in association with these structures. Anomalous assays can be associated with unaltered BIF, carbonate or haematite altered bands, low sulphides (<25% pyrite replacement), regularly banded BIF and strongly fractured BIF.
The Cameron Well prospect is interpreted to comprise structurally controlled mesothermal gold mineralisation related proximal to syenite intrusions that alter the dominant basalt host. Mineralisation is dominantly flat-lying supergene mineralisation within a deeply weathered oxide profile. Within the transitional and fresh rock component of the Mineral Resource, mineralisation is hosted predominantly by sheared basalt with a strong early biotite alteration that is overprinted by a later phase of quartz-carbonate veins and chlorite-silica-pyrite alteration associated with mineralisation. Shears are often proximal or directly adjacent to felsic intrusive dykes. In some instances, the felsic intrusions are also mineralised. Mineralised structures strike in a number of orientations including northsouth dipping to the east, west-northwest with a sub-vertical dip, north-west striking with a subvertical dip and more recently north south striking with a shallow east dip.
The Mount Marven deposit is interpreted to comprise a series of lode structures striking 330-0150 and dipping approximately 60-750 . Mineralisation is associated with haematite alteration, vein quartz content, oxidation level, silicification and coarse pyrite. Contacts between the basalt and porphyry intrusive bodies are often mineralised.
Mining Methods
- Truck & Shovel / Loader
- Longhole open stoping
Summary:
At Mt Morgans, the Company’s five year mine plan includes the continuation of mining the Jupiter open pits and recommencement of mining at Mt Marven with a southern extension following the completion of the firststage of Mt Marven. Underground mining is planned to recommence within the Greater Westralia area, with mining campaigns focussed on extraction of stoping blocks across the existing Westralia, Craic and Transvaal underground mines as well as development of a new underground mine at Phoenix Ridge.
Open pit
Mining the Jupiter open pits of Doublejay and Heffernans continues through to the end of FY2024 when the Doublejay pit is completed. A total of 5.8Mt at 1.2g/t Au for 225,000oz will be mined from Jupiter during the three year period.
After almost four years of mining, commencing in December 2017, the Heffernans pit will reach the final design floor 200m below surface during late H1 FY2022.
The Doublejay pit is mined in three stages around the historic Joanne and Jenny pits, with the stages referred to as DBJ07, DBJ15 and DBJ14. Both DBJ07 and DBJ15 pit stages are completed during FY2022, with the quantity of ore mined increasing during the second half of the year as pre-stripping is completed and the high-grade Cornwall Shear Zone (CSZ) beneath the historic Joanne pit is exposed on mining benches. The DBJ14 stage spans the three year period FY2022-24, with pre-stripping over FY2022 prior to exposing high-grade ore zones underlying the CSZ.
For the Jupiter open pit Ore Reserve, mechanised open pit mining remains the selected mining method.
Underground mining
FY2022 sees the recommencement of underground mining at Mt Morgans, with a mining campaign planned for the Westralia underground targeting extraction of stoping blocks in the vicinity of existing development within the Beresford South and Allanson mine areas. A total of 150,000t at 4.0g/t Au for 19,400oz is planned to be mined during the year. Beyond FY2022, underground mining at the Greater Westralia Area takes a staged approach, whereby the Mineral Resource contained within stoping blocks identified as being economically viable across the various underground mine areas will continue to be systematically drilled prior to investment in mine development capital. A total of 860,000t at 4.0g/t for 111,000oz is planned to be mined from the Westralia underground during the period FY2023 to FY2026.
For the Westralia underground Ore Reserve, the underground mining method of top-down long hole open stoping with pillars remains the selected mining method.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Jaw crusher
|
|
|
|
1
|
Pebble crusher
|
|
|
220 kW
|
1
|
SAG mill
|
|
8.5m x 3.5m
|
4400 kW
|
1
|
Ball mill
|
|
5.5m x 8.9m
|
4400 kW
|
1
|
Processing
- Gravity separation
- Smelting
- Intensive Cyanidation Reactor (ICR)
- Filter press plant
- Concentrate leach
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- Carbon adsorption-desorption-recovery (ADR)
- AARL elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
The Mt Morgans process plant was commissioned in late March 2018 and is designed to treat an ore throughput of 2.5 million tonnes per annum. The processing plant includes a Semi Autogenous Grinding, Ball Milling and Pebble Crushing (SABC) comminution circuit followed by conventional gravity and carbon-in-leach (CIL) process.
The metallurgical process is commonly used in Western Australian and international gold mining. The same process configuration was previously utilised at Mt Morgans during the 1990s.
A metallurgical test work program was completed during the 2016 DFS using samples from diamond drill core and RC drill chips to determine: - physical properties for comminution circuit design; - optimal grind size; and - gold recovery.
Description
The crushing and milling of ores is designed to produce a P80 passing 106 microns. The MMGP ores exhibit coarse gold able to be recovered using gravity concentrators. Leach residence time will be 28 hou ........

Recoveries & Grades:
Commodity | Parameter | 2021 | 2020 | 2019 |
Gold
|
Recovery Rate, %
| ......  | ......  | ......  |
Gold
|
Head Grade, g/t
| ......  | ......  | ......  |
Reserves at June 30, 2021:
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
8,030 kt
|
Gold
|
0.9 g/t
|
226 koz
|
Probable
|
3,301 kt
|
Gold
|
1.5 g/t
|
158 koz
|
Proven & Probable
|
11,330 kt
|
Gold
|
1.1 g/t
|
385 koz
|
Measured
|
9,130 kt
|
Gold
|
1.01 g/t
|
298 koz
|
Indicated
|
14,720 kt
|
Gold
|
1.73 g/t
|
819 koz
|
Inferred
|
8,530 kt
|
Gold
|
2.6 g/t
|
713 koz
|
Total Resource
|
32,410 kt
|
Gold
|
1.75 g/t
|
1,827 koz
|
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