Liquid-liquid extraction is a complex separation process in which the components are extracted from the feed stream with the help of an extractant, or solvent. The components to be extracted have a different solubility in the two immiscible, or partially miscible, liquids. Both liquids have to be thoroughly contacted and subsequently separated. The liquids flow counter-currently and the required purity and yield determines the number of separation stages. In the field of liquid-liquid extraction, Sulzer Chemtech’s range of equipment covers many industrial applications and is based on a number of modern and more efficient types of extractors.

1. Kühni Agitated Column (ECR) in applications with high mass transfer and/or changing physical properties, this is the column of choice. The compartment geometry can be adapted to compensate for changing conditions resulting in a constant high column performance. The main features are the special mixing turbines and the perforated partition plates.
2. Packed Column (ECP) The key benefit of a packed column is the high throughput which leads to small column diameters. Together with specially adapted liquid distributors, our structured packing provides the best extraction performance.

Mixer-settlers, both as stand-alone and as in-column type, are offered for special applications;

1. Mixer-Settler (EMS) Due to the pump-mix turbine no additional feed pumps are required in most cases.
2. Kühni Mixer-Settler-Column (ECMS) This special type of equipment combines the stage-wise operation of mixer settlers with the small footprint of a column.

Typical applications are:

• Recovery of carboxylic acids, for example, acetic acid
• Extraction of aromatics, for example, from oil
• Washing of organic solvents
• Cleaning of aqueous effluents from high boiling impurities like phenol
• Wet purify cation of phosphoric acid (food grade)
• Recovery and purifycation of Active Pharmaceutical Ingredients (API’s)
• Solvent de-asphalting
• Solvent recovery

In the short path evaporator, a vertical condenser is placed inside the wiped evaporation chamber. This results in a very short distance between the heating and condensing surface. The pressure drop across the system is thus minimized and evaporation in the pressure range below 1 mbar is feasible. Due to the short residence time, highly temperature sensitive substances and compounds with high molecular weight can be purified at high purities and yields.