Extraction with solvents, continuous theory


A fuUy continuous tiquid—tiquid extraction process in countercurrent flow enables separation into two groups of REE. Thus the separation of REE requires n + 1 countercurrent separations carried out using a column or mixer—settler arrangement (see Extraction,liquid-liquid). This limitation is, however, compensated for by continuous operation. The three-outlet mixer—settler battery is an improvement, but only two streams contain a high purity REE. A schematic flow diagram of a countercurrent flow extraction plant for the continuous separation of two REE or two groups of REE is shown in Figure I. The mixture that is to separated is fed to an intermediate stage of the contactor operating in countercurrent flow. The solvent becomes preferentially charged with the REE that form the most stable complex, while the REE that form the less stable REE complex remain in the aqueous phase. The flow extract is further washed by the scmbbing aqueous solution in order to remove traces of the less stable REE complex. The pure extract is then subjected to back extraction in order to recover a high purity aqueous solution. The solvent is then recycled.  [c.544]

Batch Percolators The batch tank is not unlike a big nutsche filter it is a large circiilar or rectangiilar tank with a false bottom. The solids to be leached are dumped into the tank to a uniform depth. They are sprayed with solvent until their solute content is reduced to an economic minimum and are then excavated. Countercurrent flow of the solvent through a series of tanks is common, with fresh solvent entering the tank containing most nearly exhausted material. In a typical ore-dressing operation the tanks are 53 by 20 by 5.5 m (175 by 67 by 18 ft) and extract about 8200 Mg (9000 U.S. tons) of ore on a 13-day cycle. Some tanks operate under pressure, to contain volatile solvents or increase the percolation rate. A series of pressure tanks operating with countercurrent solvent flow is called a diffusion battery.  [c.1673]


See pages that mention the term Extraction with solvents, continuous theory : [c.3]   
Textbook on organic chemistry (1974) -- [ c.44 , c.45 ]