Sieve plate tower extractors are liquid - liquid extractors. Sieve type extractor is the multistage, counter current sieve tray tower. They are very effective for system of low surface tension, which does not require mechanical agitation for dispersion. The stage type extractor can operate in batch or continuous basis. Small droplets of liquids are formed as the light phase flows through a perforated sieve plate, these droplets rise through the continuous heavy phase and coalesce underneath the next plate. The heavy phase flows downward from plate to plate through one or more downspouts or weirs depending on the column diameter. By turning the sieve plates upside down, heavy liquid becomes the dispersed phase. These multistage counter current columns feature a simple design with no moving parts while providing high mass transfer rates, little axial mixing between stage and overall extraction efficiency.