The ILR receives gravity concentrates or flotation concentrates into a fully enclosed rolling drum. Inside the drum, the ore concentrates are mixed typically with a 1-2% sodium cyanide solution and an oxidant, known as intensive leaching. Specialised baffles inside the drum keep the solids in constant contact with the chemical solution providing a high shear environment. The correct combination of chemicals and concentrate, plus the rolling action of the drum, creates a highly efficient leaching reaction. This drives faster kinetics primarily through mixing and attrition which is critical to remove the oxidation layer away from the surface of the gold particles and allow enriched solution containing the required reagents to access fresh. Leach rate can be directly correlated to the attrition energy absorbed.
Lifters inside the ILR drum mechanically agitate the slurry, forming an oxidant rich zone with high solids-liquids mixing for leaching. Gekko has conducted multiple comparisons on the scale- up between bottle rolls and site data, consistently demonstrating that the ILR has performed equal to, or in some cases better, than laboratory bottle rolls.
The automated ILR-B treats up to 24 tonnes per day per unit, of either gravity or flotation concentrates. The concentrates are typically low mass, high grade Au and or Ag concentrates.
The Continuous ILR-C treats concentrate masses between 1-10tph per unit based on the residence time required for economic leaching, with the systems able to be treat low grades and high grades. Both the batch and the continuous systems can be applied to both free and complex sulphide gold concentrates.
The Batch and the Continuous ILRs work to chemically leach metal from ore concentrates using the same leaching principle. The ILR’s horizontal “rolling bottle” design keeps the concentrates in suspension and continuously mixes to accelerate the chemical reaction within the solution. The rolling bottle provides a pure mixing zone, preventing the risk of the solution short circuiting.
When leaching in the batch units is complete, the pregnant ‘metal rich’ solution is clarified and transferred to an electrowinning circuit. With the continuous units, there is an additional process route. The options include the pregnant solution reporting to carbon columns, resin columns, Merril Crowe circuits and in some cases direct electrowinning can still be applied. The barren residual solution can report back to the circuit, detoxification process, recycled or in some cases a combination is applied.
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