Theory of Operation

The concentrates from the primary recovery device report to a cone for de-watering. The feed can be either continuous or batch. The feed system will continuously feed the reactor at a rate lower than the recommended maximum feed rate. The Cone underflow reports to the reactor feed while the Cone overflow is returned to the circuit.

The InLine Leach Reactor works on the principal of the laboratory bottle roll to keep the solids in contact with the liquor. A horizontal drum rotating at low speed with a set of specially designed baffles and aeration system for maximum leach performance. Residence time is predicted in the laboratory and controlled by Reactor volume. Barren solids are washed and removed from the circuit via a dewatering cone and dewatering screen. Solids report to the reactor solids discharge sump for further washing if necessary.

Pregnant liquor is pumped to the Solids Settling Vessel (SSV), remaining slimes settle to the bottom and reticulate to the solids discharge sump. The pregnant solution is pumped to the electrowin cell for Au recovery. The spent solution from the electrowin discharge is returned to the reactor feed. This vessel has a permanent overflow which will discharge excess liquor to the solids discharge sump which will be returned to the mill circuit. The flow rate of eluate from the SSV controls the rate of recirculation of liquor in the system.

Reagent Addition

Reagents are added to the Reactor feed via a dosing pump. The typical operating solution grade is recommended at around 2% cyanide at 13.5 pH. A leach accelerant (such as ProLeach) at around 0.5% may also be added if required.

High dissolved oxygen levels (+20ppm dissolved Oxygen) in the spent eluate, which reports to the reactor feed, are generated using the electrowin cell running with ambient solution. This improves leach times significantly and allows large particles to be leached with extremely low retention times.

Predicted Cost

Including Caustic, Cyanide, Power, Wear Parts, and Leach Accelerant (such as ProLeach), predicted cost is $10 - $50 per kg Au poured (dependant on gold loading in concentrates).

Batch Versus Continuous Models

The batch models of the InLine Leach Reactor have been developed to treat higher-grade lower volume gold bearing concentrates while the continuous InLine Leach Reactors have been developed to treat lower grade higher volume gold bearing concentrate streams. This allows for flexible application of intensive cyanide leaching technology for the treatment of different primary concentration methods, different ore characteristics and types.