Gold & Silver Ore — Characterizing the Deposit
Gold and silver deposits vary widely in mineralogy, grade, gangue composition and liberation characteristics. Successful gold/silver beneficiation therefore always starts with thorough ore characterization — including head-grade analysis, mineralogical examination, comminution tests and bench-scale metallurgical testwork.
WSHT's process engineering team designs gold/silver beneficiation flowsheets based on actual ore test data — ensuring the selected process matches the specific mineralogy of each deposit.
Crushing & Grinding for Gold/Silver Ores
Crushing and grinding are critical first steps in gold and silver processing, as they must liberate valuable gold and silver-bearing minerals from gangue. Typical gold/silver crushing circuits include primary jaw crushing, secondary cone crushing and tertiary crushing, followed by grinding in ball mills (or SAG + ball mill combinations) with hydrocyclone classification.
The target grind size is selected based on ore testwork, balancing recovery, energy consumption and downstream process requirements.
Gravity Concentration for Coarse Free Gold
For gold ores containing significant coarse free gold, gravity concentration using jigs, spirals, centrifugal concentrators and shaking tables is an efficient first recovery step. Gravity-recovered gold is often smelted directly to doré, reducing downstream processing complexity and cost.
Gravity tailings are then further processed by flotation and/or leaching to recover remaining fine gold and associated silver.
Flotation for Sulphide-Bearing Gold & Silver Ores
Many gold and silver deposits contain gold and silver associated with sulphide minerals (pyrite, arsenopyrite, chalcopyrite, galena, sphalerite, etc.). Flotation is the standard process for recovering sulphide-associated gold and silver, producing a flotation concentrate that is further processed by smelting, pressure oxidation or leaching.
WSHT designs complete rougher / scavenger / cleaner flotation circuits with appropriate reagent suites for each specific ore.
Cyanide Leaching — CIP / CIL / Merrill-Crowe
Cyanide leaching (using dilute alkaline sodium cyanide solution) is the dominant process for dissolving and recovering gold and silver from many ore types. Key leaching-based process flowsheets include: Carbon-in-Pulp (CIP), Carbon-in-Leach (CIL), and leach + Merrill-Crowe zinc precipitation. Each has its specific advantages depending on ore type, grade, scale and site considerations.
WSHT designs complete CIP / CIL circuits including leach tanks, carbon screens, loaded carbon elution, electrowinning and smelting / doré production.
Tailings & Environmental Management
Modern gold and silver processing plants include comprehensive tailings management systems including tailings thickening, filtration, tailings storage facility design and water recycling circuits. Cyanide destruction (by INCO SO2 / air, hydrogen peroxide or Caro's acid processes) is applied where required for environmental compliance.
WSHT's EPC solutions incorporate all required environmental and tailings management systems.