gold processing in australia

Gold processing in Australia involves several stages, from mining to refining, utilizing advanced technologies to extract gold efficiently and sustainably. Here’s an overview of the key steps and practices:

1. Mining Methods
Australia employs both open-pit and underground mining techniques, depending on the deposit:
– Open-pit mining: Used for shallow, large deposits (e.g., Boddington, Super Pit in Kalgoorlie).
– Underground mining: For deeper, high-grade ores (e.g., Fosterville in Victoria).

2. Ore Processing
Once mined, gold-bearing ore undergoes several stages:

# a. Crushing and Grinding
– Ore is crushed into smaller pieces (jaw/cone crushers) and ground into a fine powder (ball/SAG mills) to liberate gold particles.

# b. Gravity Separation (Optional)
– Used for coarse gold recovery (e.g., centrifugal concentrators, shaking tables).

# c. Flotation (For Sulfide Ores)
– Chemicals are added to make gold-bearing sulfide minerals hydrophobic, allowing them to attach to air bubbles and separate.

# d. Cyanidation (Most Common Method)
– Gold dissolves in a diluted cyanide solution (NaCN or KCN) in leach tanks.
– Activated carbon (CIP/CIL – Carbon-in-Pulp/Leach) absorbs the gold from the solution.
– Alternative: Heap leaching for low-grade ores (ore piled on impermeable pads and sprayed with cyanide).

# e. Electrowinning & Refining
– Gold-loaded carbon is treated with hot caustic solution to strip gold.
– Electrowinning precipitates gold from solution onto steel wool cathodes.
– Smelting produces doré bars (~90% pure), which are further refined to 99.99% purity.

3. Major Gold Processing Facilities in Australia
– Super Pit (Kalgoorlie, WA) – One of the largest open-pit mines.
– Boddington (WA) – Combines open-pit mining with autogenous grinding.
– Fosterville (VIC) – High-grade underground mine using flotation and intensive leaching.
*Telfer (WA) – Processes both oxide and sulfide ores.

4. Environmental & Safety Considerations
– Strict regulations govern cyanide use, tailings management, and water recycling.
– Rehabilitation programs ensure mined land is restored.