The Mining Chemical Technology (MCT) division of Cognis’ Functional Products Group is pleased to announce the granting of the US patent application to its split circuit technology that is particularly applicable to agitation leach – solvent extraction circuits of copper ores.

The split circuit configuration effectively splits the leached solution into high and low grade streams, which in turn are treated separately in the solvent extraction process.

The raffinate produced from the high grade solution is returned to the leaching step to fully re-use the acid that has been generated. Raffinate produced from the low grade leach solution, lower in concentration of both metal species and acid than would conventionally be the case, is used in the washing activity, and a portion is ultimately bled from the circuit as the soluble loss fraction.

In this way, the configuration minimizes soluble losses. Other operating improvements are realized with lower neutralization costs prior to tailings disposal.

The economic benefits of the split circuit are clearly apparent once a detailed mass balance of both the metal species and acid is performed. The relative simplicity of the concept means that incorporation into an existing flowsheet can be done easily and with a minimum of capital outlay.

The split circuit provides operational flexibility and, in areas of the world where the cost of acid and neutralizing agent are high, the operating cost benefits of the concept can be substantial.

The split circuit concept has been implemented at five copper agitation leach – solvent extraction circuits to date. The concept has also been included in feasibility studies for several other large scale projects.