Two liquid effluent streams were generated by transforming concentrates into molybdenum and rhenium products.  However, strict environmental regulations imposed upon Chilean copper giant Codelco prohibited liquid effluent discharge of any nature.

The effluent treatment plant JordProxa designed and constructed to treat this effluent, recovers clean water from this combined effluent stream for recycle to process, whilst converting the ferrous compounds into a stable, solid residue that is used to de-ice roads in the nearby high Andes mountains.  Arsenic is also removed, in a stable form within the residue rather than accumulating within the recycled water.

A two-stage process was used to achieve this; chemical pre-treatment followed by evaporation and crystallisation. The result was a significantly more compact and cost effective plant, compared to a conventional effluent treatment plant.

The pre-treatment stage was accomplished in four steps: oxidation, lime precipitation, softening and neutralisation. After these steps the effluent was a relatively pure mixture of sodium sulfate and sodium chloride.   The second stage evaporation system operated as a Zero Liquor Discharge (ZLD) crystalliser, with no purge of concentrated brine and with the mixed sodium chloride and sodium sulfate salt discharged in solid form.