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SCHEIBEL® Column for the Liquid-Liquid Extraction of Metal Ions

Towanda, PA
A northeast specialty chemicals supplier (“the client”) engaged Koch Modular for the design and manufacture of an extraction column.

The column was to be used in the liquid-liquid extraction of metal ions from an aqueous feed stream originating from the scrap recycling of tungsten filaments in incandescent light bulbs.

The client’s existing three-step mixer-settler process involved an extraction followed by washing and stripping. In the client’s process, the mixer settlers were in poor, corroded condition, and water entrainment in the organic extract phase was taking place which necessitated the need for the wash step.

Extensive pilot testing and an optimized SCHEIBEL®Column provided by Koch Modular addressed these issues for the extraction and stripping steps and resulted in an overall improved metals extraction process.

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Liquid Extraction for Metal Ions
Liquid Extraction for Metal Ions
Liquid Extraction for Metal Ions
Liquid Extraction for Metal Ions
Liquid Extraction for Metal Ions
Liquid Extraction for Metal Ions

Challenge

The client’s process involves the extraction of metal ions from an aqueous feed stream using a mixed solvent of approximately 10% of an aliphatic tertiary amine in a heavy aromatic, naphtha organic.

The client was interested in replacing the mixer settlers used in the process with an extraction column that is durable, corrosion-resistant, and minimizes the amount of acid water entrainment in the organic extract phase.

For this process application, Koch Modular engineers recommended using the SCHEIBEL®Column due to it having highest efficiency of any commercially available column based upon data published in the literature.

This column also complied with the height limitation at the client’s plant. Pilot testing was performed using feed samples provided by the client and a 3” diameter, 20 agitated stage SCHEIBEL®Column.

Variables such as capacity (combined flow of both phases), column height (number of agitated stages), solvent to feed ratio, agitation speed, and temperature were studied and optimized.

SOLUTION

Koch Modular provided a 50” inner diameter, 20-stage SCHEIBEL®Column with a 100” diameter expanded chamber at its top.

The expanded chamber was included for minimization of the amount of water entrainment in the organic extract phase.

A 6” thick coalescing element was also included in the expanded zone for removal of fine water droplets.

Reducing the amount of water entrainment resulted in the elimination of the washing step, transforming the client’s three-step process into a two-step process. The elimination of the washing step further resulted in the decreased generation of wastewater.

To provide corrosion resistance, the material of construction for column internals was chosen to be an alloy known as C-276.

The SCHEIBEL®Column installation was successful and it has been running ever since with no reported issues.