At Port Pirie in South Australia, Nyrstar operates a Solvent Extraction (SX) and Electrowinning (EW) circuit for the production of copper cathode. In the operation of this circuit organic reagents from the SX circuit are transferred to the electrolyte in the EW circuit. This transfer is undesirable from a number of perspectives, as it can cause organic burn on the copper cathode and present a loss of a valuable reagent from the SX circuit.
In Jan 2010 Fenix Hydromet commissioned an electrolyte filter system, in which the electrolyte feeding the cell house was filtered through an anthracite bed. The mechanism of removal is through coalescence of organic particles on the surface of the anthracite surface, over time the coalesced organic particles form larger droplets which then float to the surface within the vessel. The anthracite beds are also air scoured at regular intervals and the layer of organic is purged from the filter back into the SX plant.
The benefits of this process are:
- improved cathode quality
- reduction in reagent losses from solvent extraction circuit, and
- reduced fire hazard in electrowinning circuit.