Solvent Extraction (SX) is a key unit operation in the production of metals by means of hydrometallurgical processing and is one of the specialist areas in the in-house capabilities of ProProcess. It is a selective separation procedure typically employed to purify and concentrate valuable metals from an aqueous solution, utilising an organic solvent.
One of the challenges associated with SX plants is the effective management of contamination by entrainment of the process streams exiting the SX circuits. A common contaminant experienced by all SX operations is the entrainment of the SX organic reagent in the raffinate and advance electrolyte streams. The adverse impacts of excessive organic entrainment in these streams are elevated reagent consumption costs, impact on copper cathode quality and elevated health and safety risks in the electrowinning tankhouse.
The organic skimming recovery systems are designed to recover organic reagent from the surface of SX process ponds within the solvent extraction–electrowinning circuit. The system consists of Elastec patented drum oil skimmer technology that has been adapted to process environments associated with hydrometallurgical solvent extraction-electrowinning processes.
Typical applications of these systems include organic recovery from SX raffinate ponds, organic recovery from advance electrolyte after-settlers and recovery of spilled organic from the bunded areas of SX plants. Unlike many other organic skimming systems the unit is ATEX rated and can be applied safely within the SX complex.
A number of drum skimmer units are available, however the preferred unit of choice by many SX operators is the Minimax oil skimmer. The unit is compact and light-weight, making it easy to reposition from one application to the next. The unit consists of an air driven, float-mounted dual drum skimming system, which is positioned on the target pond, after-settler or SX bund. The drums recover organic which is collected in an organic collection launder within the float system. The collected organic is pumped away to the client’s organic recovery area by means of a diaphragm pump.
Used to collect organic from the surface of the process ponds, the organic skimming recovery system can be used in conjunction with containment booms that are used to control the spread of organic prior to its recovery. An important aspect of ProProcess’ involvement with Elastec in the implementation of the Elastec range of organic recovery products is the upgrade of key components in order to make the units compatible for the more aggressive corrosive environment associated with hydrometallurgical SX plants.