A gold concentrate processing plant is designed to extract gold from ore that has already been concentrated through methods like gravity separation, flotation, or other beneficiation techniques. The plant typically includes several stages to refine the concentrate into pure gold. Below is an overview of the key processes involved:
1. Receiving & Storage of Gold Concentrate
– The plant receives pre-concentrated material (e.g., from a mining operation or gravity/flotation circuit).
– Storage facilities ensure a steady feed for continuous processing.
2. Pre-Treatment (If Required)
– Drying (if moisture content is high).
– Crushing & Grinding (to optimize particle size for leaching).
3. Gold Extraction Methods
Depending on the type of concentrate, different extraction methods are used:
# A. Cyanide Leaching (Most Common)
– The gold concentrate is mixed with a dilute sodium cyanide (NaCN) solution.
– Gold dissolves into the solution as a cyanide complex.
– Activated carbon (CIP/CIL – Carbon-in-Pulp/Carbon-in-Leach) may be used to adsorb gold from the solution.
# B. Smelting (For High-Grade Concentrates)
– Direct smelting in a furnace (with fluxes like borax and silica) to separate gold from impurities.
– Produces doré bars (~90% purity) for further refining.
# C. Alternative Non-Cyanide Methods
– Thiourea Leaching – Less toxic than cyanide but more expensive.
– Chlorination – Uses chlorine gas to dissolve gold.
– Bioleaching – Uses bacteria to break down sulfides and release gold.
4. Gold Recovery & Refining
– Electrowinning – For cyanide solutions, gold is plated onto cathodes.
– Mercury Amalgamation (Rarely used due to toxicity risks).
– Miller Process – Chlorine gas treatment to refine gold to ~99.5% purity.
– Wohlwill Process – Electrolytic refining for 99.99% pure gold.
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5. Tailings Management & Environmental Controls
– Cyanide detoxification (if used).
– Tailings storage facilities with proper containment.
– Water recycling to minimize waste.
Key Equipment in a Gold Concentrate Processing Plant
– Ball mills / Rod mills (grinding)
– Leaching tanks
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