Placer Gold Processing Flowchart
Raw Ore Preparation
Excavation of placer gold deposits from alluvial, eluvial, or coastal environments.
Crushing and washing to remove large debris and clay.
Screening & Classification
Use of vibrating screens or trommels to separate oversized gravel (>20mm).
Hydraulic classification (e.g., spiral classifiers) to group particles by size and density.
Gravity Separation
Primary concentration equipment:
Sluice Boxes: Capture gold via riffles and matting.
Jigging Machines: Separate heavy minerals using pulsating water.
Shaking Tables: Refine concentrates through stratified motion.
Secondary recovery: Centrifugal concentrators (e.g., Knelson or Falcon separators).
Concentration & Refining
Manual or mechanical cleaning of gravity concentrates.
Final refining methods:
Amalgamation (mercury-based, now largely phased out).
Cyanidation (for fine gold using leaching tanks).
Smelting to produce gold bullion.
Tailings Management
Recycling water to minimize waste.
Neutralizing harmful substances (e.g., residual mercury/cyanide).
Land rehabilitation for environmental protection.
Key Equipment
Trommel Screens
Sluice Boxes
Jig Separators
Shaking Tables
Centrifugal Concentrators
Leaching/CIP (Carbon-in-Pulp) Systems
Features
Low energy consumption.
Environmentally friendly compared to hard-rock mining.
High recovery rate for coarse and free-milling gold.
