Overview
Stage | Production |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Gravity separation
- Smelting
- Concentrate leach
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- Carbon adsorption-desorption-recovery (ADR)
- AARL elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 10 years (as of Jan 1, 2018) |
Mt Morgans Gold Operation (MMGO) comprises a 2.5 Mtpa CIL treatment plant, the Jupiter open pit and Westralia underground mining areas. On september 2020, Westralia was placed on care and maintenance. |
Latest News | Dacian marches into 2021 with Mt Morgans expansion goal January 5, 2021 |
Source:
p. 46, 108
Mt Morgans Gold Operation is 100% owned by Dacian Gold Ltd.
Deposit Type
- Vein / narrow vein
- Banded iron formation
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.
Summary:
The Dacian Gold’s three year outlook from FY2021-2023 is predominantly underpinned by open pit ore sources, with continuation of production from Jupiter mine area and mining of the Mt Marven open pit.
OPEN PIT MINING
Jupiter mine area comprises three sub-pits named Doublejay, Saddle and Heffernans. Open pit mining commenced at Jupiter in December 2017 with Heffernans Stage 1. Production is currently focussed in Heffernans Stage 2 with pre-stripping of Doublejay Stage 1.
The Heffernans sub-pit remained the primary source of high-grade ore feed to the processing plant during 2020.
Pre-stripping of the Doublejay Stage 1 pit commenced early in the June quarter 2020 as planned and will transition to become the dominant source of ROM ore feed during late FY2021.
Mining of a cut-back at the historical Mt Marven pit, located some 2km from the processing plant, commenced in July 2020 as planned and will be a further source of ROM ore feed throughout FY2021.
Mechanised open pit mining has been selected as the mining method. This method consists of drill and blast, excavator and truck open pit mining and is the same method currently employed at the Jupiter open pit.
To take advantage of synergies with mining at Jupiter, mining equipment selected is the same as currently in use at Jupiter. This will result in a modest increase in fleet size at the site whilst Mt Marven and Jupiter open pits are being mined concurrently.
Geotechnical recommendations have been applied during pit optimisation and incorporated into detailed pit design. Minimum mining bench widths of 30m and minimum mining cutback widths of 20m have been used for the pit design.
UNDERGROUND MINING
Ore drive development was completed across the Beresford South, Beresford North and Allanson mine areas at Westralia in May 2020 as planned (see ASX announcement 31 July 2020) and stoping continued on remaining production levels. Mining ceased in August 2020 following the completion of these planned stopes.
Beresford and Allanson deposits were mined using underground long hole stope mining.
Development of a Holistic Underground Strategy
Mount Morgans Gold Operation currently has four underground projects in its pipeline, namely the Westralia, Phoenix Ridge and Transvaal deposits and the Craic project. The Company is currently assessing the mining potential of all its underground deposits, with the view that a holistic strategy could optimise the Resource inventory.
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
- 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 | 2020 | 2019 |
Gold
|
Recovery Rate, %
| ......  | ......  |
Gold
|
Head Grade, g/t
| 1.6 | 1.71 |
- Subscription is required.
Reserves at January 1, 2020:
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
5,994 kt
|
Gold
|
0.9 g/t
|
165 koz
|
Probable
|
10,871 kt
|
Gold
|
1.7 g/t
|
589 koz
|
Proven & Probable
|
16,866 kt
|
Gold
|
1.4 g/t
|
754 koz
|
Measured
|
6,287 kt
|
Gold
|
1.2 g/t
|
243 koz
|
Indicated
|
20,444 kt
|
Gold
|
1.9 g/t
|
1,252 koz
|
Inferred
|
5,323 kt
|
Gold
|
3.4 g/t
|
574 koz
|
Total Resource
|
31,962 kt
|
Gold
|
2 g/t
|
2,067 koz
|
Aerial view:
- Subscription is required.