Organic recovery from SX crud, using the Flottweg TRICANTER ® centrifuge

Solvent Extraction Crud Persistent problem in most SX/EW facilities Solid stabilized emulsion which accumulates at aqueous/organic interface

Crud problems Interferes with phase separation Increases physical entrainment which can –result in loss of pH control in extraction circuit –reduce extraction efficiency –cause cathode burn in the EW section –result in organic losses to the leach circuit Regular removal of crud from SX cell essential Pumped out from phase interface of settlers In some cases entire settlers have to be drained to remove crud build-up

Solvent Extraction Crud Traditionally treated in filter presses Filter presses very inefficient at recovering the organic High organic losses are common Cost of replacing organic ranges from several hundred thousand to millions of dollars per annum

Flottweg TRICANTER ® Solid-Liquid-Liquid Separation solids discharge light liquid phase discharge by gravity feed inlet heavy liquid phase discharge under pressure

TRICANTER ® operation Heavy phase discharged under pressure through adjustable impeller Adjustable impeller allows control over pond depth of both phases Adjustments can be made during operation Optimises purity of the phases

TRICANTER ® operation Typically crud is expected to consist of three phases: –Solids –Aqueous –Organic Lab test and field results have shown that a 4th phase can occur –Ultra fines particulates The TRICANTER ensures that the ultra fines go out with the aqueous phase

TRICANTER ® Options Bearing temperature monitoring Shock pulse monitoring to detect worn bearings Belt-slip monitoring of drive belts Automated greasing system Vapour or gas tight design Variety of drive system

Z4E-3/441 TRICANTER ® Commissioning a TRICANTER ® at a Cu refinery in Zambia

Case Study – Bwana Mkubwa, Zambia Late 2003 Severe crud problems Needed to drain settlers periodically to de-crud Crud filtered in filter presses to recover organic High crud losses due to inefficiency of filter press Early 2004 Invested US$ in Z4E-3/441 TRICANTER ®

Case Study – Bwana Mkubwa, Zambia TRICANTER ordered January 2004 Commissioned June 2004 Organic losses in crud reduced drastically Settlers no longer need to be drained Saving on organic losses around US$ /month Payback period for centrifuge around 5 months

Crud – Before & After

Thank you for your interest.