RECYN III PROCESS FLOWSHEET
Slurry Flow Resin Flow Solution Flow
Carbon Safety Screen U/F Metal Eluted Resin
Resin Sizing Screen
Flocculant
NaSH
Precipitate Thickener
Loaded Resin Screen
H 2 SO 4
NaOH
Copper Elution Column
Metal Adsorption Tank
Filter Feed Tank
Copper Reactor Tank
Loaded Resin Tank
NaCl
Copper Filter
Copper Concentrate
Zinc Filter
Zinc Filtrate
Gold Elution Column
Zinc Reactor
NaCN soln
Electrowinning Cell
ZnSO 4 .7H 2 O
Gold Eluant
Zinc
Gold Bullion
Drying Oven
Furnace
Cyanide Eluted Resin
Scrubbing Column
Resin Sizing Screen
Loaded Resin Screen
NaOH
Ventilation
Cyanide Adsorption Tank
Cyanide Elution Column
Safety Screen
Recycle Cyanide Solution to Leach Tank
Recycle Cyanide Tank
Loaded Resin Tank
H 2 SO 4
Tailing Dam
Tailings Hopper
Fig. 3. ReCYN III Flowsheet
Operations with low copper levels can by-pass the chloride elution step, using the gold elution step to remove the copper and other metal cyanide complexes. The final stage in the gold elution is resin regeneration, which uses sulphuric acid to remove the zinc that has loaded onto the resin during the copper and gold elution. The zinc is recovered by precipitation and recycled to the gold eluant tank. RECYN CHEMISTRY The ReCYN process is based on the use of a strong base, macroporous, anionic, polystyrene resin beads. The resin is sized to provide a +1mm diameter bead and partially pre-conditioned prior to use. Resin production methods have improved over the years to ensure a robust product, resilient to osmotic shock and abrasive wear. However, this does not apply to all suppliers. The ReCYN process ensures minimum resin handling to reduce resin abrasion losses. The ReCYN circuit can contain fifty billion beads of resin (approximately), forming a homogenous mix of several resin forms. The form of each resin bead entering metal adsorption will depend on its elution history. Copper eluted resin will be in the chloride form and gold eluted resin will be in the sulphate form. Both forms of eluted resin will adsorb metal cyanide complexes. Some free cyanide will also be adsorbed. The cyanide recovery circuit is kept separate to maximise the copper loading and therefore maximise free cyanide recovery. At the start of commissioning a ReCYN plant, conditioned resin is added to the cyanide adsorption train. For conditioning, the new resin is pre-treated with a synthetic copper cyanide solution (similar
ALTA 2020 Gold-PM Proceedings
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