What is Ore Beneficiation?
Ore beneficiation is the process of separating valuable minerals from gangue (waste rock) in mined ore to produce a saleable mineral concentrate or product. Beneficiation typically begins with crushing and grinding to achieve mineral liberation, followed by one or more concentration processes: gravity concentration, flotation, magnetic separation and / or hydrometallurgical leaching. The choice of beneficiation technology depends on ore mineralogy, liberation size, mineral type and plant scale.
WSHT designs complete beneficiation flowsheets for a wide range of mineral types and deposit sizes.
Gravity Concentration
Gravity concentration separates minerals of different density using gravity forces alone (augmented by centrifugal force in modern gravity equipment). Gravity processes include jigs, spirals, shaking tables, centrifugal (Knelson-style) concentrators and dense-medium separation (DMS). Gravity concentration is widely applied to free-milling gold, tin, tungsten, tantalum, chrome and iron ore deposits.
Gravity concentration is simple, low-cost and environmentally benign — but is only applicable where significant density differences exist between valuable minerals and gangue.
Flotation
Froth flotation is the dominant concentration process for sulphide minerals (copper, lead-zinc, nickel, cobalt, molybdenum) and for many non-sulphide minerals (phosphate, fluorite, graphite, rare-earths, oxide copper after sulphidization). Flotation exploits the differential wettability of mineral surfaces: valuable minerals are rendered hydrophobic by chemical reagents, attach to rising air bubbles and are recovered in a froth product.
WSHT designs complete rougher / scavenger / cleaner flotation circuits including reagent preparation and dosing, slurry handling and automatic level and airflow control.
Magnetic and Electrostatic Separation
Magnetic separation exploits the magnetic properties of minerals. Low-intensity magnetic separators (LIMS / drum magnetic separators) are used for strongly magnetic minerals such as magnetite. High-intensity magnetic separators (WHIMS / wet high-intensity and dry high-intensity magnetic separators) recover weakly magnetic minerals including hematite, ilmenite and certain industrial minerals. Electrostatic separation exploits differences in electrical conductivity for dry separation of certain mineral mixtures.
Magnetic separation is clean, low-cost and widely used — particularly for iron ore upgrading.
Hydrometallurgy — Leaching, Solvent Extraction and Electrowinning
Hydrometallurgy uses aqueous chemical processing to dissolve and recover valuable metals from ore or concentrate. Important hydrometallurgical processes include: cyanide leaching with CIP/CIL (gold / silver); sulphuric acid leaching for oxide copper and cobalt ores, followed by solvent extraction and electrowinning (SX-EW); alkaline leaching; pressure acid leaching (PAL) for nickel laterites; and pressure oxidation (POX) for refractory gold and complex sulphide concentrates.
WSHT designs crushing, grinding and physical beneficiation circuits for hydrometallurgical feed preparation, and partners with specialized technology providers for the hydrometallurgical refining stages.
Tailings and Environmental Management
All beneficiation processes generate tailings — fine waste rock material that must be safely managed and eventually rehabilitated. Modern tailings management includes tailings thickening, filtration, water recycling, dry stacking and engineered tailings storage facility (TSF) design. Environmental management is an integral part of every WSHT-designed beneficiation plant.
Good tailings and environmental management reduce water consumption, lower environmental impact and improve community and regulatory acceptance of mining operations.
