Stawell is a historic goldfield that produced 2.7 million ounces of gold between 1853 and 1926 from both alluvial and hard rock sources. There was little mining activity in the Stawell area from 1926 to 11th March 1976 when Western Mining Company (WMC) Resources Ltd was granted an exploration licence over the Stawell Goldfield.
In 1981 SGM was reopened by the WMC/Central Norseman Gold joint venture with commencement of the Magdala decline. By 1984 the operation had expanded with the construction of a processing facility and subsequent commencement of an open cut operation at the Wonga mine (2 kilometres south of Magdala). A number of historical tailing dumps were retreated during this period. Towards the end of mining of the Wonga open cut (1987) the Davis open cut operation was commenced. The Davis open cut exploited the oxide material on up dip projection of the Magdala deposit. The Wonga Open Cut operated from 1984 to 1987 and produced 778,847 tonnes recovering 69,159 ounces of gold. The Davis Open Cut operated from 1987 to 1989 and produced 154,525 tonnes for 8,992 recovered ounces of gold.
In December 1992 the operation was acquired in a 50/50 joint venture by Mining Project Investors (MPI) Pty Ltd and Pittston Mineral Ventures (Pittston). At this stage the Magdala decline was approximately at 410m RL, while the Wonga decline was at 180-200m RL. With the acquisition there was a clear direction to increase expenditure on resource definition drilling and near mine exploration. The joint venture continued until 2004 during which time there was a record of continued exploration success with discovery of additional mineralized deposits that were subsequently mined.
In February 2004 MPI acquired the Pittston 50% share of the project. Exploration continued in the Golden Gift area during 2004 with the commencement of the Golden Gift South surface exploration program. In November 2004 a de-merger of the MPI gold business came into effect, and Leviathan Resources Ltd was floated in December 2004. The resource drilling into the Golden Gift initially identified seven areas of mineralisation offset from each other due to late faulting. Conversion of these areas of mineralisation into ore blocks wasn’t universal but was successful in a majority of cases. The further drilling of the fault blocks also identified other mineralised surfaces previously unknown due to the faulted nature of the Golden Gift. From the increased geological understanding of the Golden Gift deposit, it was clear in the mine planning process that two declines were required, the GG5 and GG3 declines, to access the ore zones for continuity of supply.
In January 2007 Perseverance acquired Leviathan Resources Ltd. Perseverance was acquired by Northgate on the 18th of February, 2008. Northgate was acquired by AuRico in October, 2011. Crocodile Gold completed their acquisition of Stawell Gold Mines from AuRico on May 4th, 2012.
Stawell Gold Mines is located in the Australian State of Victoria, 250km northwest of Melbourne and 2km from the township of Stawell (Figure 4-1). Stawell is a rural township of approximately 6500 people and is within the Northern Grampians Shire.
Stawell Gold Mines is easily accessible from Melbourne via the Western Highway. Access closer to the mine site is provided through a network of sealed bitumen government roads. Roads within the mine site are unsealed and regularly maintained. The main Melbourne to Adelaide rail line passes through the town of Stawell, which is also serviced by a local sealed airfield.
The town of Stawell is located within the southern part of the Wimmera where the climate is described as semi-arid, allowing for exploration and mining activities all year round. Since 1996, Stawell has recorded an annual daily average temperature of 20.5°C. An extreme maximum of 43.6°C was recorded on the 25th of January, 2003, and an extreme minimum of 3.7°C on the 4th of August 1997. Mean annual rainfall is 480.2 millimetres with 70 days per year on average recorded as having rain.
Stawell Gold Mines has been in operation for over 25 years, developing a highly experienced workforce. Many contractors, also having a long association with the mine, are available in the township of Stawell and surrounding regions. Due to the mines close location to the town of Stawell many facilities are available. Within the township is a police station, hospital, schools and shops. Mains Electricity and water is also accessible.
Stawell Gold Mines facilities are extensive and representative of a modern gold mining operation. On the surface facilities include the gold processing plant, offices, core shed, laboratory and workshops. Larger infrastructure onsite includes a tailings dam, covering 96 Ha and receiving 100% of gold tailings from the processing plant. Three freshwater dams occur throughout the mine lease. The mine purchases electric power under a two year contract from Origin Energy Australia that expires in Dec 2012.
Mining Method and Processing
The Magdala mine is accessed by a decline from a portal located adjacent to the mill. The mine access development and services are located mainly within basalt. Ground conditions are good and there is no history of major seismic activity. Development follows the Magdala Lode system down plunge and between 470RL and 786RL the decline splits into a north and a south decline to access the Golden Gift ore bodies. To facilitate ore access, extraction levels are developed at approximately 20m to 25m vertical intervals. The mining areas currently extend over approximately 3km of strike to more than 1,500m below surface, measured from the top of Big Hill.
The mining method used in the Magdala mine was bench stoping with cemented rock fill pillars in primary stopes, and rock filled secondary stopes. The mining method used in the Golden Gift and narrow Magdala ore zones is retreat open stoping with either cemented rock fill (CRF) if full extraction or combinations of CRF and rock fill or all rock fill stope with pillars. In the Magdala ore body, stope sizes typically range from 2,000 to 10,000 tonnes. In the Golden Gift area where the width and tenor of the reserves have so far been of higher quality, generally larger stopes up to 15,000 tonnes are expected. Stope ore is recovered using loaders under direct or remote control of an operator, with haulage by 60 tonne trucks.
The gold processing facilities utilised at SGM comprise a standard Carbon-In-Leach (CIL) gold recovery circuit following crushing and grinding and sulphide flotation. Current processing capacity is 1.0mm tonnes per annum.
Stawell Gold Mine Localization Map