The Mt Rawdon gold deposit is a massive intrusive-related low grade gold deposit that exhibits excellent characteristics conducive to low cost mining and treatment. Alluvial gold was first discovered on the hill flanks in 1946 leading to early mining endeavours however the gold grade was too low to be profitable in those times. The gold mineralisation is closely associated with fine disseminated pyrite and base metal sulphides as well as in irregular discrete veinlets within the igneous host rocks. The gold grade is statistically independent of the sulphide percentage of the host however. The host rocks are predominantly rhyodacitic intrusives, breccias and a related volcaniclastic pile, with the orebody dipping moderately to the south west.

Mining production is derived from a single open pit, utilising conventional drill and blast, load and haul methodologies, mining 10-15m benches. The operation is scheduled to continue until FY25 at current estimates with a remaining life of mine strip ratio of 2:1.

Primary crushing/grinding plant/machinery:
Allis Charmers 42/65 superior gyratory

Secondary crushing/grinding plant/machinery:
Jaques J65. Pre screen with double deck Joest vibrating screen. Synton feeder to screen and bypass
using an overflow bin for lump. Nominal reduction ratio of 5-1 (125mm primary crush to 25mm secondary crush).

Grinding plant equipment:
Dominion 28’ SAG, Nordberg 42/70HG ball mill.

Grinding media:
High manganese steel, 125mm ball (steel lined SAG mill) 64mm balls (rubber lined ball mill). Grind size 60% -106µm.

Recycle crusher:
Autofine 736 Cone Crusher (Allis Chalmers).

The Mt Rawdon processing plant consists of primary and secondary crushing, SAG and ball milling, followed by conventional cyanidation leaching. Gold feed is recovered through a gravity circuit prior to the flotation circuit to produce dore gold bars which are sold to the ABC Refinery in Sydney.

Ore treatment/processing method/s:cConventional crush-grind-CIL to produce gold dore.
Annual average throughput rate: 3.24Mtpa (FY19).

Nameplate capacity of plant: 3.5Mtpa.

Mineral liberation/recovery method: CIL.

Mineral liberation plant/equipment: 1 x 1,500m3 leaching tank, 5 x 1,500m3 adsorption tanks.

Gravity circuit: Knelson Concentrator 13% of gold recovered by gravity.

Process pumps: Warman 10/12 split casing.

Chemical/reagents used: Air Liquide (oxygen), Unmin (lime), Elgas (LPG), IXIM (HCl, caustic), Orica (cyanide), Jacobi (carbon).

Refining plant/equipment: 8t AARL elution column.